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- Front Matter: Volume 7656
- Session 3-1
- Session 3-2
- Session 3-3
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Front Matter: Volume 7656
Front Matter: Volume 7656
Show abstract
This PDF file contains the front matter associated with SPIE Proceedings Volume 7656, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.
Session 3-1
Phase retrieval in situ measurement for large aperture parabolic mirror
Show abstract
Phase retrieval is a promising method for in-situ metrology and has been applied to spherical mirror surface metrology
successfully. To meet the requirement of in-situ measurement in manufacturing large aperture parabolic mirror, a new
method using phase retrieval technology is developed. In this method, an approximately parallel beam is used to
illuminate the large parabolic mirror. The beam is produced by a point light source far away from the tested mirror.
Then, intensity of diffraction patterns near the focus is measured by CCD. The experiment of testing a parabolic mirror
with aperture 400mm and radius of curvature at vertex 2789.7mm is described. And some advices of improving the setup
are presented. Errors brought by the approximately parallel beam are compensated by an algorithm derived from GS
iterative algorithm. Phase retrieval result is consistent with that measured by interferometer sub-aperture stitching in
error distribution, PV value and RMS value. The experiment shows that this method features simple optical path, good
anti-vibration ability and acceptable accuracy.
Subaperture stitching based on Hartmann wavefront sensor
Yu-mei He,
Guo-mao Tang
Show abstract
A new method of subaperture stitching based on Hartmann-Shack wavefront sensor is presented to solve the testing of
large-aperture optical systems and components. The measured full aperture is divided into several area apertures, a
Hartmann wavefront sensor is used to sense the wavefornt informations of each area aperture one by one. Modifying
factors of errors are obtained by the overlapping area between two adjacent area aperture, the wavefront information of
full aperture which can get by stitching algorithm and wavefront reconstruction algorithem . Proving in theory,
simulation and testing experiment are given in this paper, the results shows the effectiveness of the method. It is simple
and faster compared with other wavefront stitching algorithm, which can be used for testing the large optical systems and
components.
Optimizing operating parameters of spectrophotometer for testing transmission spectrum of optical substrate
Huasong Liu,
Dandan Liu,
Yiqin Ji,
et al.
Show abstract
The optical characteristics of substrates are the essential content of research work for thin film optics. The
spectrophotometer is one of the important instruments to test transmittance and reflectance of different substrates or
coating components. The test accuracy of transmission spectrum of the substrates has direct influenced on optical
constants reverse engineering of thin film on the substrate. In this paper, SCHOTT grade LITHOSIL_Q0 fused silica
substrate was chosen as standard substrate and was tested transmission spectrum in region 380nm-860nm to use the
Lambda-900 spectrophotometer. By comparing the measured transmission spectrum with standard SCHOTT grade
LITHOSIL_Q0 fused silica substrate transmission spectrum can be calculated measured errors. In the experiments, the
orthogonal experimental design method is used. Sample pool aperture, scan speed, slit width and sampling data interval
operating parameters were chosen as key factors (three levels were chosen in each factor). L9 (34) orthogonal table was
used for analysis the experiments results. Nine experiment results analyzed to determine the operating parameters of the
influence measured accuracy were as follows: the sample pool aperture, scan speed, slit width, the sampling data interval.
Finally, no iris, scan speed 250nm/s, slit width 3nm, sampling data interval 1nm were used a combination of the
operating parameters to measure of transmission spectrum of the SCHOTT grade LITHOSIL_Q0 samples. Measured
maximum and minimum absolute error are 0.1355% and 0.0771%, respectively. The operating parameters could be
applied to transmittance spectrum test of every substrate, or the spectrum could be extended.
Fiber Bragg grating demodulatin system based on ARM and LabVIEW
Show abstract
A novel FBG sensing signal demodulation system based on ARM7 and LabVIEW8.6 is proposed. Matching FBG
demodulation method is used to demodulate the luminous intensity signal. The screw attached to stepper motor is
controlled by ARM7 microprocessor to impel the cantilever and makes the matching FBG adhered on the cantilever to
scan the Bragg wavelengths offset of the sensing FBG. With the synthetics curve of the steps of the motor and Bragg
wavelengths of the sensing FBG, we can calculate the tiny offset of wavelength and realize the intention of FBG sensing
signal demodulation. After being processed by the weak signal processing circuit and AD convert circuit, the electrical
signal converted from the luminous intensity signal enters the MCU. The data coming from the ARM is filtered by the
LabVIEW and displayed on the PC. The maximal strain measuring range of 1100με and the measuring accuracy of ±1με
are archived in the experiment. The experiment shows that the result of strain tested and the theory one have a good
linear relationship.
Design of null tests for an F/0.8 concave oblate elliptical surface
Show abstract
Aspheric surfaces are widely used in aerospace sensing optic instruments. There are numerous reflecting optical system
designs that call for oblate elliptical surfaces, such as secondary mirror or tertiary mirror in three mirror anastigmat
(TMA). The consequence brought by increase in field of view (FOV) and speed of optical system is the decrease in F/#
of aspheric surface which makes its production harder. Due to oblate ellipsoid's stigmatic points are not lined up on the
optic axis, null lenses corrector is used more often than the stigmatic null test especially in low F/# aspheric surfaces test.
Three types of null lenses tests for an oblate elliptical surface with aperture Φ360mm, F/0.8, conic=0.243 are presented
including a new type which is modified by replacing the reference flat and null lens with one lens with reflect surface.
Furthermore, sensitivity tolerances for each design are practiced.
Phase modulating two Fabry-Perot interferometry and its application to nanometrology
Bin Gou,
Lei Zhu,
Jian Miao,
et al.
Show abstract
We discuss how to expend the SPM of double beam interferometer to multi-beam interferometer or Fabry-Perot
interferometer and deduce the corresponding theoretical results in this paper. Besides the introduction section 1 the
principle of Fabry-Perot interferometer and how to simplify the representation of its intensity are described in section 2.
Two typical conditions such as (1) nearby the maximum and fineness coefficient F, the light phase θ satisfied the
condition F sin2θ < 1 or (2) offset the maximum and F θ satisfied the condition F sin2θ > 1 considered. Phase
modulating Fabry-Perot interferometry and theoretical results for 1, ramp, 2, saw teeth, 3, sinusoidal voltage
modulating or SPM Fabry-Perot interferometer are deduced in section 3. It should be noted that the construction of
double Fabry-Perot interferometer for nanometrology and the experimental results are stated in section 4. Our
measurement resolution could be arrived in <0.3nm using the method of time space difference.
Study of ocean red tide multi-parameter monitoring technology based on double-wavelength airborne lidar system
Show abstract
For monitoring and forecasting of the ocean red tide in real time, a marine environment monitoring technology based on
the double-wavelength airborne lidar system is proposed. An airborne lidar is father more efficient than the traditional
measure technology by the boat. At the same time, this technology can detect multi-parameter about the ocean red tide
by using the double-wavelength lidar.It not only can use the infrared laser to detect the scattering signal under the water
and gain the information about the red tise's density and size, but also can use the blue-green laser to detect the Brillouin
scattering signal and deduce the temperature and salinity of the seawater.The red tide's density detecting model is firstly
established by introducing the concept about the red tide scattering coefficient based on the Mie scattering theory. From
the Brillouin scattering theory, the relationship about the blue-green laser's Brillouin scattering frequency shift value and
power value with the seawater temperature and salinity is found. Then, the detecting mode1 of the saewater temperature
and salinity can be established. The value of the red tide infrared scattering signal is evaluated by the simulation, and
therefore the red tide particles' density can be known. At the same time, the blue-green laser's Brillouin scattering
frequency shift value and power value are evaluated by simulating, and the temperature and salinity of the seawater can
be known. Baed on the multi-parameters, the ocean red tide's growth can be monitored and forecasted.
Application of wavelet analysis in laser Doppler vibration signal denoising
Yu-fei Lan,
Hui-feng Xue,
Xin-liang Li,
et al.
Show abstract
Large number of experiments show that, due to external disturbances, the measured surface is too rough and other factors
make use of laser Doppler technique to detect the vibration signal contained complex information, low SNR, resulting in
Doppler frequency shift signals unmeasured, can not be demodulated Doppler phase and so on. This paper first analyzes
the laser Doppler signal model and feature in the vibration test, and studies the most commonly used three ways of
wavelet denoising techniques: the modulus maxima wavelet denoising method, the spatial correlation denoising method
and wavelet threshold denoising method. Here we experiment with the vibration signals and achieve three ways by
MATLAB simulation. Processing results show that the wavelet modulus maxima denoising method at low laser Doppler
vibration SNR, has an advantage for the signal which mixed with white noise and contained more singularities; the
spatial correlation denoising method is more suitable for denoising the laser Doppler vibration signal which noise level is
not very high, and has a better edge reconstruction capacity; wavelet threshold denoising method has a wide range of
adaptability, computational efficiency, and good denoising effect. Specifically, in the wavelet threshold denoising
method, we estimate the original noise variance by spatial correlation method, using an adaptive threshold denoising
method, and make some certain amendments in practice. Test can be shown that, compared with conventional threshold
denoising, this method is more effective to extract the feature of laser Doppler vibration signal.
Super-smooth surface defects measurement and evaluation system
Xin Gao,
Yongying Yang,
Peng Zhao,
et al.
Show abstract
According to ISO10110-7 surface defects standard, a super-smooth surface defects measurement and evaluation system
is established. High quality defects image is acquired by a specific microscopic dark-field scattering imaging device.
Combined with a precise XY-scanning system for sub-scanning the optics surface, panoramic surface defects image
could be obtained. Surface defects imaging model is discussed in view of scattering. In the new system, LED is used as
the emitting source to realize system illumination. Compared with the halogen tungsten lamps, the new light source has
less weight and smaller size. According to the practical situations of defects images, probable mismatches of template
matching method of original system are analyzed, a feature based multi-cycle image mosaic algorithm is developed to
mosaic sub-aperture defects images. In the new algorithm, images are mosaicked in an order which is decided by the
results of feature extraction in their overlapping areas. Feature extraction is firstly carried out to recognize defects
features in the overlapping areas of images. Images with defects in their overlapping areas are mosaicked in the way of
region growing to form many image blocks. Then images and image blocks with no defects in overlapping areas will be
combined into panoramic image according to the nominal displacement distance of the stage. A complete set of image
preprocessing, recognizing and evaluating is established to extract defects features and calibrate. With this system,
reliable recognition, pinpoint and accurate evaluation of surface defects could be rapidly, automatically realized, with a
resolution reaching micron-level.
Kossel diffraction and conformation investigation of colloidal crystals
Hao Yang,
Chao Wang,
Zhibin Sun,
et al.
Show abstract
Kossel-line diffraction method is an important way to measure the structure of crystals. Colloidal
crystal is one of the hotspots on the condensed physics research. The paper investigates the kinetics
process of crystallization on several hundreds nanometer particles in aqueous. In order to obtain the
diffraction image, a 473nm wavelength laser is used to irradiate samples, and then the Kossel-line
image of sample is projected onto the translucent screen and recorded by IEEE 1394 charge coupled
device (CCD) cameras. Especially, gravity convection effects can be eliminated under microgravity
environment, therefore the research of growth mechanism of colloidal crystals in the space has great
scientific significance. The crystallization processes of three kinds of colloidal solution are investigated
in the temperature field and electric field by means of the shear-flow assisted. Finally, laser diffraction
images and white conformation images can be analyzed for exploring the phase-change rule of
colloidal crystals. Besides, parameters can be adjusted online by remote control function in order to
improve the flexibility of experiments.
Practical testing device for fluorescence lifetime on μs with LCD display
Jing Li,
Gang Zhai,
Bin Wang
Show abstract
Based on laser crystals, the testing principle of fluorescence lifetime on μs is introduced and a practical device on this
principle is designed. The testing system includes exciting source, light path system, detecting circuit, signal disposing
circuit and LCD display circuit. Achieved by pulse sampling technique, this device with small size can display the
fluorescence lifetime value on LCD directly and reliably, and it measures the fluorescence lifetime of Nd:YAG crystal
and doped Nd glass in lab as 240μs or 330μs separately which conforms to the theoretical value very well.
Study and considerations of nanometer and nano-radian surface profiler
Show abstract
A Nanometer and Nano-radian Surface Profiler (NSP) is under development at Brookhaven National Laboratory.
Nanometer and nano-radian accuracy is required for newest state-of-the-art synchrotron radiation optics and highprecision
optical measurement. This test accuracy must be maintained in larger angle test range. In order to reach this
accuracy we have to remove all error sources as much as possible or to reduce them to nano-radian level. We present the
approaches in optimized optical system designing, scanning optical head mode selection, non-tilted reference method,
quality control of optical components, and temperature stabilization. Some considerations and preliminary measurements
are presented.
Session 3-2
Eliminating noises contained in sensing signals from a self-mixing laser diode
Show abstract
The paper studied the noise elimination methods for the signals observed from a self-mixing-laser diode (SM-LD) based
sensing system. The core part of the sensing system consists of a LD, a lens and an external vibrating target. The
proposed noise elimination methods are applied on both the simulated and experimental sensing signals. The results
presented in the paper show the noise contained in the sensing signals can be effectively eliminated. As a consequence,
the vibration trace of the target can be reconstructed with high accuracy using this sensing system.
Polarization point-diffraction interferometer for high-precision testing of spherical surface
Daodang Wang,
Yongying Yang,
Chen Chen,
et al.
Show abstract
As a promising measurement tool for ultra-highly accurate testing of optical elements, the point diffraction
interferometer has got good application in the high-precision spherical surface testing. It employs a nearly ideal spherical
wavefront diffracted by a pinhole, enabling the measurement precision in the order of sub-nanometer. However, the poor
fringe contrast due to low reflectivity of spherical surface under test, limits the measurement precision in process of
fringe pattern analysis. In order to realize high-precision testing of spherical surface with adjustable contrast of fringe
pattern, a polarization point diffraction interferometer (PPDI) is introduced, and the adjustable fringe contrast is realized
by controlling the polarization states of reference and test beams. The interferometer has many advantages, such as
simple in structure, easy to align and with adjustable fringe contrast. In order to achieve high accuracy, the main sources
of systematic error and the corresponding calibration method have been studied in detail, including the spherical quality
of diffracted wavefront, the wavefront distortion by polarizing elements, aberrations by geometric structure of the
measurement system and optical properties of adopted elements and so on. The theory of the interferometer is presented,
along with results of computer simulation. The analysis shows the proposed method can realize an accuracy of subnanometer
level, and it is of great practicality for high-precision testing of spherical surfaces with low reflectivity.
Novel metrological tuning fork atomic force microscope for optical surface characterization
Jian Zhao,
Tong Guo,
Long Ma,
et al.
Show abstract
A novel metrological tuning fork atomic force microscope (M-TFAFM) with an Abbe error free design is presented,
which is aimed at traceable topographic and non-destructive characterization of the optical surfaces. Unlike the
traditional AFM, the M-TFAFM does not need any optical detector to measure the bending of the cantilever,
significantly saving the working space. A z-axis piezoelectric positioning stage (z-PPS), with high resonant frequency, is
responsible for the rapid motion of the sample in z-direction. A high-end digital signal processing (DSP) servo control
system further guarantees high measurement speed. A nano-measuring machine (NMM) is equipped as the lateral
moving stage to realize three-dimensional measurement of the optical surfaces. Three interferometers in the NMM
enable the measurement to be traced to the meter definition. In order to enhance the reliability of measurement, a
convenient calibration method is designed. The results of the experiments show a good performance of the system.
Identification and quantification of non-commonpath error in lateral shearing interferometry
Bingcai Liu,
Ailing Tian,
Hongjun Wang,
et al.
Show abstract
The lateral shearing interferometry based on four step phase shifting has been widely used for aspherical surface
measurement, but the non-commonpath error is the main factor that directly affects the measurement results. Based on
the structure of lateral shearing aspherical surface interferometer with phase shifting, the non-commonpath components,
such as the beam splitter cubes, shearing plate and two right angle prisms, are adopted to produce the displacement of
wave-front of under test aspherical surface, because of these components with manufacture errors, the under test wavefront
will become deformation when it goes through them, and these wave-front deformations will be performed in the
shearing interferograms, therefore, the measurement results obtained by the shearing interferograms compromise the
non-commonpath error. In this paper, through analyzing four step phase shifting interferograms with a shearing value
and four step phase shifting interferograms with no displacement, the identification and quantification methods of noncommonpath
error were put forward, then, the non-commonpath error can be subtracted to correct the measurement
results, finally, the simulation and experiment results demonstrate the feasibility of this approach to improve
measurement accuracy.
Study on the transverse chromatic aberration of the individual eye model after LASIK refractive surgery
Mei Zhang,
Zhao-Qi Wang,
Yan Wang,
et al.
Show abstract
The aim of this research is to study the properties of the transverse chromatic aberration (TCA) after the LASIK
refractive surgery based on the individual eye model involving the angle between visual axis and optical axis. According
to the measurements of the corneal surfaces, the optical axis lengths and the wavefront aberrations, the individual eye
models before and after LASIK refractive surgery are constructed for 15 eyes by using ZEMAX optic design software,
while the angle between the visual axis and optical axis is calculated from the data of the anterior corneal surface. The
constructed eye models are then used to investigate the variation of the TCA after the surgery. The statistical distributions
of the magnitude of the foveal TCA for 15 eyes over the visible spectrum are provided. Finally, we investigate the
influence of the TCA on the visual quality and compare the results with previous research. The TCA is an indispensable
criterion to evaluate the performance of the refractive surgery. This research is very meaningful for the studies of not
only foveal vision but also the peripheral vision.
Test of visible spectral transmittance of large aperture optical lens
Show abstract
It is difficult to measure the transmittance of large aperture optical lens, when incident beam runs in a wide angular range
and in a scanning way, especially of those with different apertures in the same setup. Here an automatic spectrometer
setup has been built, which can measure the transmittance of various large aperture optical lens in the visible spectrum. It
is composed of a coordinated four-axis mechanical system, sample fixtures and an advanced optical system. It can give
one-dimensional scanning result of samples with varied surface apertures in a wide range of incident angle, as well as at
a fixed point. The incident angle of the testing beam is allowed to range from -80° to 80° . Moreover, various
measurement errors and corresponding solutions were discussed in this paper. It has been proved that this spectrometer
setup can give results accurately.
Nondestructive measuring soluble solid contents and weight of intact pears based on on-line near-infrared spectroscopy
Yuanyuan Pan,
Xudong Sun,
Xiaoling Dong,
et al.
Show abstract
The objective of this study was to investigate the potential of NIRS as an accurate, reliable and nondestructive method to
measure SSC and weight parameters of intact pears. The effects of fruit moving speed on SSC and weight prediction
were evaluated. Diffuse reflectance spectra of 200 samples were collected by a fiber spectrometer in the range of
840~950nm at 5 different speeds: 2, 3, 4, 5 and 6 fruits per second. One-way analysis of variance (ANOVA) method was
employed to assess effect of speed with partial least squares regression (PLSR). At the speed of 4 fruits per second, five
types of data pretreatment were adopted before calibration. Multiple linear regression (MLR), principal component
regression (PCR) and PLSR models were developed in the calibration set (n=150). 50 unknown samples were applied to
evaluate the performance of the models. SSC was measured with a root mean squares error of prediction (RMSEP)
comprised between 0.60 and 0.88 °Brix and correlation coefficient (r) between 0.57 and 0.85. As far as weight was
concerned, the best results were obtained by PLSR combined with smoothing spectra (r=0.93, RMSEP=14.29 g). The
results demonstrated that on-line NIRS was feasible for measuring SSC and weight of intact pears nondestructively.
Overview on the profile measurement of turbine blade and its development
Show abstract
Turbine machinery has an extraordinary wide range of applications in the aviation, aerospace, automotive, energy and
many other industries. The turbine blade is one of the most important parts of turbine machinery, and the characteristic
parameters, pressure ratio of the engine and rotating speed of the turbine are all related to the shape and size of blades.
Therefore, the profile measurement of turbine blade is an essential issue in the blade machining processing, however, it is
difficult and particular to establish the profile measurement of turbine blade because of its complicated shapes and space
angles of the blades, and the specific stringent environmental requirements need a more appropriate measurement
method to the Turbine Blade profile measurement. This paper reviews the recent research and development on the
Turbine Blade profile measurement methods, which mainly describes several common and advanced measurement
methods, such as the traditional coordinate measuring machines, some optical measurement methods with the
characteristics of non-contact like optical theodolite, three-dimensional photography, laser interferometry, as well as the
laser triangulation method studied more recently and so on. Firstly, the measuring principles, the key technical issues and
the applications in the Turbine Blade profile measurement of the methods which are mentioned above are described
respectively in detail, and the characteristics of those methods are analyzed in this paper. Furthermore, the scope of
application and limitations of those measurement methods are summed up. Finally, some views on the current research
focus and perspective trend of the Turbine Blade profile measurement technology are presented.
Performance of mode-biased wavefront sensor to detect multiple aberration modes
Show abstract
We investigated the performance of mode-biased wavefront sensor(MWFS) to detect aberration including multiple
modes. Two important parameters, Sensitivity and dynamic range, were chosen as criterions to evaluate the performance
of the MWFS. We describe the tested wavefront as the superposition of several aberration modes, and considered it in
three situations, in which the tested wavefront including: (a) only identical modes,(b) only relevant aberration modes,(c)
only irrelevant aberration modes , relative to the biased ones. We show that the existence of the above three types of
aberration modes in the tested wavefront greatly impacts the detection performance of the MWFS in terms of the
sensitivity and dynamic range.
Error analysis and system optimization of non-null aspheric testing system
Yongjie Luo,
Yongying Yang,
Dong Liu,
et al.
Show abstract
A non-null aspheric testing system, which employs partial null lens (PNL for short) and reverse iterative optimization
reconstruction (ROR for short) technique, is proposed in this paper. Based on system modeling in ray tracing software,
the parameter of each optical element is optimized and this makes system modeling more precise. Systematic error of
non-null aspheric testing system is analyzed and can be categorized into two types, the error due to surface parameters of
PNL in the system modeling and the rest from non-null interferometer by the approach of error storage subtraction.
Experimental results show that, after systematic error is removed from testing result of non-null aspheric testing system,
the aspheric surface is precisely reconstructed by ROR technique and the consideration of systematic error greatly
increase the test accuracy of non-null aspheric testing system.
Error analysis of spherical ultra-precision measurement
Show abstract
Absolute interferometric testing of spherical surfaces is one of effective methods for ultra-precision testing, which can
eliminate the systematic errors. In this paper, we discuss the absolute measurement of spherical surfaces and analyze the
influence of errors existed in the organism comprehensively. To improve the testing precision, it is necessary to remove
the alignment errors such as tilt and defocus. The traditional methods remove alignment errors by low-level
approximation, so they may be not effective for the small F-number surface. To solve this problem, we propose a novel
measurement with high-order approximation model. The simulation and experiment results show that: while the error
between high-order approximation model and low-level approximate model is small on tilt, it is large on defocus, and the
error will become larger when the F-number of testing surface becomes smaller; alignment errors can be well adjusted by
our high-order approximation model.
Hybrid phase retrieval algorithm for solving the twin image problem in in-line digital holography
Show abstract
For the reconstruction in the in-line digital holography, there are three terms overlapping with each other on the image
plane, named the zero order term, the real image and the twin image respectively. The unwanted twin image degrades the
real image seriously. A hybrid phase retrieval algorithm is presented to address this problem, which combines the
advantages of two popular phase retrieval algorithms. One is the improved version of the universal iterative algorithm
(UIA), called the phase flipping-based UIA (PFB-UIA). The key point of this algorithm is to flip the phase of the object
iteratively. It is proved that the PFB-UIA is able to find the support of the complicated object. Another one is the Fienup
algorithm, which is a kind of well-developed algorithm and uses the support of the object as the constraint among the
iteration procedure. Thus, by following the Fienup algorithm immediately after the PFB-UIA, it is possible to produce
the amplitude and the phase distributions of the object with high fidelity. The primary simulated results showed that the
proposed algorithm is powerful for solving the twin image problem in the in-line digital holography.
Some novel combining approaches to reduce speckle noises
Xu Yang,
Zebin Fan,
Jinbin Gui,
et al.
Show abstract
In the optical test and measurement, speckle noise is a commonly noise which spoils the quality of the optical images,
therefore, how to eliminate this kind of noise and keep the high frequency detail is an important subject, there have been
presented many approaches such as adaptive median filtering in space domain, low pass filter in frequency domain and
wavelet based approaches. Different filter has its own advantage and disadvantage, some filtering method is complicated
and inconvenient for practice application. And the wavelet-based methods usually blurred the image. Therefore to find a
simple and robust filtering method is valuable and important for speckle reduction. In this paper on the bases of theory
analysis and simulation, an approach which combines the advantage of wavelet analysis, adaptive median filtering and
Gauss filtering technique have been presented. The de-noising effect is evaluated with Signal to Noise Ratio (SNR), The
simulation results demonstrate that the combining de-noise approaches are better than single method.
Automatic procedure for non-coplanar aberration compensation in lensless Fourier transform digital holography
Show abstract
As the lensless Fourier transform digital holography is applied into the microscopic phase-contrast imaging on the live
cells, the motion of the cells will lead to the non-coplanarity phenomena between the object and the reference source.
This could result in the imaging aberration. An effective and robust autofocus procedure based on the phase distribution
is presented in the paper. With the initial measurement of the distance between the reference source and the hologram,
the optimum parameters corresponding to the phase-contrast image can be achieved by a single hologram, combined
with the linearity fitting. The lensless Fourier transform digital holographic system is built and the experiments on the
phase-contrast imaging of the live cervical carcinoma cells are performed. Finally, the good experiment results are
demonstrated. Both the theoretical analysis and the experimental investigation verify the feasibility and validity of the
automatic procedure for the non-coplanar aberration compensation.
Session 3-3
Certification, self-calibration, and uncertainty in testing optical flats
Show abstract
Many different approaches may be taken in the certification of reference flats used for acceptance testing of optical
quality surfaces. Measurement services offered by national measurement institutes cover a limited size range and the
uncertainties associated with the transfer of a calibration must be considered when data from any testing service is used
in quality assurance. In-situ self-calibration using a full area variant of the 3-flat test enables the lowest possible
uncertainty. The first part of this paper shows the options for external calibration and certification as a function of flat
size, and orientation. Next the conditions that must be met to achieve traceability, according to the requirements of ISO
17025, will be discussed. Finally hardware and procedures will be described, and data presented, showing traceable
measurement of a 450 mm aperture flat with nm level uncertainties.
Research on time-resolved terahertz spectroscopy
Show abstract
We have built a set of terahertz time-domain spectroscopy system using electro-optic crystals. Conventional terahertz
time-domain spectroscopy based on Fourier-transform for spectra analysis, which mixes the frequency components of
the entire temporal terahertz waveform in one frequency domain; therefore, it yields different terahertz spectra from a
same terahertz pulse with different scanning lengths. We introduce a new technique for the joint time-frequency analysis
of terahertz time-domain spectroscopy based on wavelet-transform technique. With this technique, the frequency
components in different time locations are clearly exhibited on a two-dimensional plane; therefore, the noise in the pulse
tail cannot affect the frequency in the main pulse. This technique clearly separates the frequency of terahertz from that of
its echo in the time domain; therefore, the interference spectrum occur in Fourier-transform is naturally removed. By
varying the shape of analysis wavelet, high time resolution and high frequency resolution are easily obtained. The
absorption coefficients of envelope, plastic, foam and cotton have been measured with the wavelet technique.
Determining the profile parameters of photoresist grating with spectrum deductive method
Show abstract
In process of fabricating the pulse compression grating (PCG), before the photoresist grating's profile is etched into the
substrate with multilayer dielectric stack, the profile parameters, i.e. the groove depth, residual thickness and duty cycle
which directly affect the diffraction efficiency of the PCG are required to be measured. A non-destructive detecting
method to determine the profile parameters which is based on analyzing the 0th order diffracted spectrum of the
photoresist grating is present in this paper. An optimization function of variable profile parameters is defined in this
method. By means of the direct search algorithm approach, the profile parameters are derived from the spectrum of the
0th order diffracted light for the 1740lp/mm photo-resist grating with definite dielectric stack and the Littrow incidence
angle. Numerical simulation results show that: when the value of optimization function is set under 1%, the difference of
the groove depth and the difference of duty cycle between the deduced value and the target value are less than 10nm and
2% respectively. The 0th order diffraction spectrum from 400nm to 700nm is obtained by the spectrometer. Then the
profile parameters of the photo-resist grating are deduced from the measuring spectrum. The deducted result is compared
with the result provided by the SEM. It shows that the spectrum deductive method is an effective method in determining
the depth and duty cycle of photoresist grating with multilayer dielectric stack. At the end of the paper, the factors
affecting the precision of deducing are discussed, too.
Performance comparison of optical path difference calculation algorithms for wavelength scanning interferometry
Show abstract
Frequency-scanning interferometry is a very useful absolute distance and areal surface profile measurement technique as
it generates absolute optical path difference without any mechanical scanning. It is thus critical to select an appropriate
algorithm to precisely and rapidly acquire the phase with respect of the wavenumber and optical path difference of the
interference fringe. In this paper we analyze and demonstrate in detail the processing speed and accuracy of current
optical path difference calculation algorithms. It is pointed out that the algorithm based on Fourier transform - inverse
Fourier transform has the highest performance in terms of calculation time and overall noise insensitivity, while the
phase shifting algorithm has the highest calculation accuracy when noise level is low.
Study of optimum pumping intensity at Cs vapor magnetometer
Show abstract
The paper describes a new magnetometer with Cs vapor in the spin exchange relaxation free (SERF) regime. Because
cesium atom has a higher saturated vapor pressure than other alkali metallic atoms, so the magnetometer has required
lower operated temperature. We have discussed the effect of different pumping intensities on the polarization and the
pumping rate at 105°C in theory; and the result shows out the magnetometer will have maximum sensitivity when the
pumping intensity is 52mW/cm2. Taking into account all relaxations including collision relaxations, diffusion relaxation
and pumping relaxation from pump light, we find the relaxation rate will be about 6Hz for the cesium magnetometer
with SERF.
Surface roughness measurement by digital holography
Show abstract
Surface roughness is crucial guideline to the surface quantity of work piece. This paper demonstrates a simple approach
for measurement of surface roughness by using digital holography imaging method based on reflection off-axis lensless
Fourier transform (LFT) holography. The surface profiles of the standard roughness sample plates which have the
different arithmetic average height values are used as the measurement sample. Comparing the arithmetical average
height values of the roughness sample plates obtained from the experiment with the given parameters, the results are in
good agreement. It has shown that the method is reasonable and efficient.
Application of the laser scanning confocal microscope in fluorescent film sensor research
Show abstract
Confocal microscopy offers several advantages over conventional optical microscopy; we show an experimental
investigation laser scanning confocal microscope as a tool to be used in cubic boron nitride (cBN) film-based fluorescent
sensor research. Cubic boron nitride cBN film sensors are modified with dansyl chloride and rhodamine B isothiocyanate
respectively. Fluorescent modification quality on the cubic boron nitride film is clearly express and the sensor ability to
Hg2+ cations and pH are investigated in detail. We evidence the rhodamine B isothiocyanate modified quality on cBN
surface is much better than that of dansyl chloride. And laser scanning confocal microscope has potential application
lighttight fundus film fluorescent sensor research.
Dynamic closed-loop test for real-time drift angle adjustment of space camera on the Earth
Jun Hu,
Xiaotao Cao,
Dong Wang,
et al.
Show abstract
In order to eliminate the influence of aircraft attitude angle to the image quality of space camera, and assure that the drift
angle of space camera could be accurately adjusted at the orbit, a novel closed-loop test method is provided for real-time
drift angle adjustment of space camera on the Earth. A long focal length dynamic aim generator is applied to simulate the
image motion and the variety drift angle, and to detect the precision of the image motion compensation machinery and
the capability of the drift angle control system. The computer system is used to control the dynamic aim generator,
accomplish the data processing, transmit and receive the data information. The seamless connection and the data
transmission between the aim generator and the aircraft simulation devices are constituted. The command, parameter and
drift angle data transmitted by the simulation devices are received by the space camera at the real time, then the photos
are taken and the draft angle is adjusted simultaneously. It is shown that the drift angle can be accurately tracked by the
space camera at the real time, and the detective method satisfies the test requirement.
Investigation of a laser frequency stabilization method based on linear magneto-optics effect
Show abstract
Recent progresses in the investigation of nonlinear magneto-optics effects and the field of exploring fundamental
physical problems became possible largely due to the development of various frequency stabilized diode laser systems.
The typical frequency stabilization method is based on saturated absorption spectrum, which usually just stabilizes the
frequency to the center of the resonance line. In this paper, a laser frequency stabilization method is investigated based
on linear magneto-optical effect, which can extend the frequency stabilization tuning range to the wings of the resonance
line. The optical system is a sequence of a linear polarizer, a cesium atomic vapor cell, a λ/4 plate and a Wollaston prism
to separate two polarizing beams. The outgoing lights are detected by two photodiodes with the same type to get the
differential signal of intensities. With fixed angle of the λ/4 plate respect to the Wollaston prism, a small rotation of the
polarizer will produces a common offset of the differential signal, which will lead to movements of the zero-crossing
point along the frequency detuning axis. This behavior can be used to tune the laser frequency on the wings of the
resonance line. To analyze the properties and the theoretical value of differential signal of our experimental frequency
stabilization system, Jones matrix approach is used. The experimental results show that this method can be used in laser
frequency stabilization by extending the frequency tuning range to the wings of a resonance line.
Effects of mechanical inaccuracies on the measurement result in metrology systems
Show abstract
Metrological systems commonly consist of a mechanical axial framework. However, any mechanical inaccuracies
in such axial systems may cause falsifications in the measurement results. Therefore, precise knowledge of
the effects of mechanical inaccuracies on measurement results is essential for measurement error compensation.
This paper discusses the results of a testing series with a topographical coordinate measurement machine for
the measurement of precision optical components in order to analyse and specify the different effects of mechanical
inaccuracies on measurement results. The results obtained are not only beneficial for the design of new
measurement machines and techniques. They may also be advantageously used for rapid measurement error
compensation in metrological systems.
Study on phase retrieval of a single closed fringe interferogram in radial shearing interferometer for aspheric test
Show abstract
The radial shearing interferometer that is immune to vibration and the spatial phase modulation technique that can
retrieve the phase from a single interferogram can be used for precise measurement of aspheric surfaces. However, as a
carrier is needed to be introduced in the system to keep the fringes open, the spatial phase modulation technique
generally leads to a great increase in the density of the fringes. A novel method that uses just one frame of the
interferogram and need not introduce any spatial carrier in the interferometer is proposed in the paper. To demodulate the
closed interferograms generated in the system, a regularized phase-tracking technique that can be used for a single open
or closed fringe pattern is employed to recover the phase map. Actually the presented method can also be applied in
many other cases, for example flow visualization. Both computer simulation and experimental result have demonstrated
the validity and efficiency of the proposed method.
Development and innovation on integrated engineering optics system design
Quanxin Ding,
Hua Liu,
Liwei Zhou
Show abstract
Answer the new challenge in project research and development on multiple subjects multiple domain, engineering
optics, system design and essential methods applied to structure effective system. Base on system engineering theory,
traditional optical design optimization is developed. General global optimization, which based on central optics system
integrated with up-to-date comprehensive modules and methods in created way, is presented and supported by abundant
results of research and development, especially on multiple configuration and adaptive system optimization. Advantages
such as system intellect, response ability, research periods, venture eluding and compatibility for renew situations
demonstrate validity and potential.
Uniform illumination for large area digital speckle pattern interferometry using multibeam
Show abstract
Using Digital Speckle Pattern Interferometry (DSPI) method measuring the large object in practice, the
primarily problem is uniform illumination. This paper presents a method that using multiple laser
beams to enlarge the illumination area and analysis the non-uniform illumination influences for
interferogram. We design an illumination model using 10 semiconductor lasers for interferometer, and
corresponding experiment shows that this method is suitable for industrial measurement in large area
detection.
Zernike polymomials for rectangular area and applications in off-axis asphere testing
Pinjiang He,
Xiaoying Zong,
Ruimin Fu
Show abstract
Zernike polynomials play a very important role in manufacture and measurement of optical element and system. They
are orthogonal within the defined unit circle, which makes them having advantages in representing wave fronts and
surface errors of circular regions. Zernike polynomials are not orthogonal in a rectangular or other shape region, which
limits their extended applications. As optical elements with rectangular aperture are used more and more frequently in
optical imaging systems such as remote sensors, there is a requirement for adapting Zernike polynomials in rectangular
regions. One answer is to generate an orthogonal polynomial set by Schmidt-Grahm orhogonalization method. The
expression of an orthogonal polynomial for rectangular area has been derived. A set of 2-dimension color contour figures
representing the values of these polynomials has been plotted, and are compared with those of 'ordinary' Zernike
Polynomials for circular region. It shows that the distribution of the 'peaks' and 'valleys' in these figures is very similar
to that of 'ordinary' Zernike Polynomials. The derived Zernike Polynomials for rectangular area have been successfully
applied in interferometric testing procedure of a rectangular off-axis asphere mirror. The coefficients of the polynomials
in rectangular aperture are calculated and used to guide the fine alignment in the interferometric testing procedure. The
tested results show that the adjustment of rectangular off-axis asphere testing system become easier and the testing
efficiency is improved.
Apparatus for femtosecond laser measurement
Qing Sun,
Yuqiang Deng,
Shiying Cao,
et al.
Show abstract
Compact and stable fringe resolution autocorrelation apparatus and spectral phase interferometry for direct electric-field
reconstruction apparatus have been established. The spectral phase, pulse profile and pulse width can be accurately
measured with the home-made apparatus. We have performed theoretical and experimental studies on spectral phase
retrieval and pulse profile reconstruction. A wavelet transform technique has been introduced to the spectral phase
retrieval process to eliminate the uncertainty which produced from the filter window. According this method, precise
spectral phase can be obtained. As a result, precise pulse profile can be reconstructed. The results from the two apparatus
have an excellent agreement.
Poster Session
Detection of infrared dim targets based on crossover matching evolution operator
Hai ying Zhang,
Xuan Wen
Show abstract
For the detection of infrared dim targets to enhance the performance of detection, following the TBD schedule in this
paper the multi-level crossover and matching operator is presented. During pre-processing the compound kernel function
and high order correlation filter are given to remove clutter without recur to the dynamical equations. In data association
stage the Greedy principle is adopted to handle the time complexity in DPA and at the same time crossover matching
operator is given to construct and choose target trajectory. During the post processing, based on the characteristic of the
targets we perform multi-information association in order to suppress false alarm further more. By the comparison and
analysis of experiments it can be found that the method is more prefer to strengthen the tracking performance of targets
with SNR<2.0 dB.
Research on Doppler frequency in incoherent FM/CW laser detection
Kai Liu,
Zhanzhong Cui
Show abstract
The principle of transmitted and received laser in incoherent FM/CW laser detection is different from the one in coherent
FM/CW laser detection. The methods for distance solution in both detections are similar. Incoherent FM/CW laser
detection uses subcarrier to modulate the intensity of laser, and the photodetector detects the intensity of received signal.
The amplified photocurrent is mixed with local oscillator signal, and the intermediate frequency (IF) signal contains the
information of distance from sensor to target. The Doppler frequency for this detection is related with the relative radial
velocity between sensor and target. The optical frequency is directly modulated with electro-optic device in coherent
FM/CW laser detection and the received laser signal is photomixed with transmitted laser signal. The Doppler frequency
in the detection relates to the optical frequency. In distance-measuring lidar, the Doppler frequency affects the solution.
The Doppler frequency in incoherent FM/CW laser detection is unrelated with optical frequency, and it is much less than
the one in coherent FM/CW laser detection, correspondingly. The error in incoherent FM/CW laser detection is smaller.
As a result, the incoherent FM/CW laser detection is more suitable for the use of distance-measuring lidar.
Measurement of the Muller matrix for painted surfaces with a kind of scatterometer
Show abstract
The polarized light scattered by the surface of a material contains information that can be used to describe the properties
of the surfaces. Polarized Bidirectional Reflectance Distribution Function (BRDF) is one of the most important factors
used to represent the property of the surface. It uses a 4×4 matrix (Mueller matrix) to describe the properties of the light
scattered from the surface. In order to measure the Mueller matrix of the samples, a new three axis automated
scatterometer has been developed to measure the Mueller matrix of painted surfaces. It can do measurement at any
illumination and viewing geometric of the hemisphere and it is more convenient for far-field measurement is presented.
The design of the instrument is different to the traditional scatterometer. The significant characteristic of the instrument
is that the detector and polarization analyzer are fixed, while the source and the incident optical elements rotate on a
stage together. All the possible incident and viewing positions can be reached through the rotation of three motors. The
rotations of the motors are fed back through photoelectric- encoders, the "closed loop" control mode ensured the
precision of the position. Through coordinate transformations, the measurement in three dimensions can be simplified in
two dimensional form, the details of the coordinate transformations will be described in detail in this paper. The dualrotating
retarders method is used to modulate polarizing and analyzing optics. Two retarders rotate synchronously at
angular speed and respectively. For every position, 16 measurements were done, and the Discrete Fourier
Transform (DFT) method is used to retrieve the Mueller matrix of the sample. Discrete Fourier Transform (DFT) method
is used to retrieve the Mueller matrix of the sample. The results of out-plane polarized bidirectional reflectance
distribution function for samples coated with different paints are presented.
Study on vertical bright line image of CCD camera irradiated by laser
Show abstract
When the CCD camera is irradiated by laser, there will be "vertical bright line" phenomeno with the power of incident
laser to a certain extent. The "vertical bright line" can not be explained by the original theory of overflow crosstalk. In
this paper, the charge-transfer process as an entry point is analyzed, and the formation mechanism of the "vertical bright
line" is revealed.
Wall-drag effect of dense Brownian particles close to solid-liquid interface in low-coherence dynamic light scattering
Hui Xia,
Fushi Li,
Zhiquan Chen
Show abstract
The wall-drag effect on diffusion of colloidal particles close to the interface wall is investigated by using a
low-coherence dynamic light scattering (Low-Coherence DLS). The low-coherence DLS provides a path-lengthresolved
measurement in concentrated suspensions and allows us to study the constrained diffusion of the colloidal
particles. It is experimentally illustrated that the reduction of the diffusion coefficient close to the interface wall is
contributed by the wall-drag effect from the low-coherence DLS measurements. The availability of low-coherence DLS
for studies of interactions between particles and interfaces is discussed.
Novel optical fiber sensor for deformation measurement
Haiting Di,
Suping Sun,
Jianqiang Yu,
et al.
Show abstract
A light intensity modulation optical fiber sensor, which can measure deformation directly, has been developed. A light
leakage zone is introduced on one side of fiber to increase the sensitivity of fiber under deformation. The machining
process of sensor is considered. Hand carving, milling and embossing methods are introduced to produce the light
leakage zone respectively, and the comparison between these methods is carried out. To obtain the static curve of sensor,
cantilevered beam, simple support beam and cylinders are used respectively to measure little and large deformation. The
static characters of sensor, such as sensitivity and measurement range, are analyzed from the static curve. The
experimental results show that the sensor can distinguish the direction of deformation (positive bending and negative
bending). Positive bending increases the throughput of light, and is distinguishable from negative bending, which
decreases the throughput. The output of sensor is linear with curvature when the curvature radius is larger than 60mm.
The response of sensor is a cosine function with the direction of deformation and there is a maximum sensitivity
direction (perpendicular to the light leakage zone plane and passing through the axis of the fiber) and a minimum
sensitivity direction (parallel to light leakage zone plane and pass through the axis of the fiber). The dynamic responds of
attenuation vibration and sawtooth input signal are studied. Comparison between the optical fiber sensor, untreated fiber
and strain gauge shows that the sensor is 400 times of untreated fiber in sensitivity and is more advantageous in
measurement of thin structures. The sensor is easily made by multi-mode plastic optical fiber and the detection
equipments are very simple, therefore it is small in size, simple in structure and low in cost, which make the sensor can
be widely used in various fields.
Multiple location analysis method for the detection of point targets
Xuan Wen,
Hai-ying Zhang
Show abstract
In order to enhance the performance of detection of multiple dim point targets, according to the TBD(Track Before
Detection) themes starting with improving the tracking performance multiple location analysis is presented in this paper.
During coarse location, the heuristic segment is created by searching the state with local max likelihood and then we
carry out fine location based on three point correlation analysis. The offset position can be corrected by being kept or
abounded. So that we can achieve the satisfied tracking results without building the dynamic equations. Finally,
hypothesis tests are put in practice and thereby the real targets will be filtered out. After experiments comparison it can
be proved that it has priority in speed and space and can guarantee high detection ratio according to CFAR criterion.
Image detection of pantograph slide basedoOn yang-shot mode
Peng-yan Shi,
Li Wang,
Xiao-rong Gao
Show abstract
At present, most of the pantograph slide images used for slides wear detection based on the image processing are
obtained by using overhead mode, but this way has some limitations for some complex arched., The purpose of this
study based on the yang-shot mode is to build detection system about slides wear. Firstly, 2 CCD cameras shoot the
pantograph slide images, and they are transmitted and stored in the host detection by video capture card. Then the edges
of saving image are detected, and the edges of pantograph slides and contact wire are located. The result showed that in
this way, we can obtain the simple background and high contrast gradient of images. It is easy to detect edges, and to
provide the significant data for detecting the pantograph slides wear volume of the remaining.
Simultaneous determination of benzo[k]fluoranthene and perylene using excitation-emission matrix fluorescence
Show abstract
Benzo[k]fluoranthene (BkF) and perylene (Per) are among the sixteen priority pollutants of polycyclic aromatic
hydrocarbons recommended by The United States Environment Protection Agency (EPA). In this paper, we report a
simple and rapid method for quantitative analysis of BkF and Per using the three-dimensional excitation-emission matrix
(EEM) fluorescence coupled with parallel factor analysis (PARAFAC). Before analyzing of two mixtures quantitatively,
we study the fluorescence characterization of pure BkF and Per first. The maximal peak values are at 306 nm of the
excitation wavelength and 406 nm of the emission wavelength for BkF, and 252 and 438nm for Per, the linear ranges of
BkF and Per are 0.8~16~ L-1 and 0.6~20~ L-1 respectively. Finally the average recoveries are obtained using
PARAFAC algorithm, which can reach 101.1% and 99.5% for BkF and Per respectively. In order to evaluate the
accuracy of the PARAFAC algorithm, selectivity (SEL) and sensitivity (SEN) have also been presented. Results show
that a good performance has been achieved using excitation-emission fluorescence coupled with PARAFAC algorithm.
Intensity-modulated and temperature-insensitive fiber Bragg grating vibration sensor
Show abstract
An intensity-modulated, fiber Bragg grating (FBG) vibration sensor is proposed and experimentally demonstrated. The
sensing mechanism is based on the measurement of optical power of a strain-chirped FBG. An initially-uniform FBG is
glued with a slanted direction onto the lateral surface of a simply-supported beam (SSB). A mass is fixed in the middle
of the beam, which can transfer the vertical vibration to the deflection of the beam. Therefore, deflection induced
nouniform strain is applied along the sensing FBG and makes it chirped. The reflected optical power from the FBG is
measured with a photodetector (PD) and an oscilloscope. The experimental results are compared with the measurement
results of a resistance strain sensor, and good agreement is achieved. Furthermore, this sensor is cost-effective and
inherently insensitive to temperature.
Reconstruction algorithm realization with FPGA based on the emission spectral tomography
Biyan Leng,
Xiong Wan,
Zhimin Zhang,
et al.
Show abstract
Reconstruction for Emission Spectral Tomography(EST) is based on thick and fast digital signal processing all along,
and the computation quantity is astronomical. With the acknowledgement of SIRT, the parallel computing of FPGA and
the flexibility of NIOS II high-speed computing power are well used. Through the hardware description language
VERILOG HDL and costuming macros module as well as the embedded system NIOS II, then achieved the purpose of
the reconstruction for EST.
Evaluation of kinetic constants of biomolecular interaction on optical surface plasmon resonance sensor with Newton Iteration Method
Yuanyuan Zhao,
Guoliang Jiang,
Jiandong Hu,
et al.
Show abstract
In the immunology, there are two important types of biomolecular interaction: antigens-antibodies and receptors-ligands.
Monitoring the response rate and affinity of biomolecular interaction can help analyze the protein function, drug discover,
genomics and proteomics research. Moreover the association rate constant and dissociation rate constant of
receptors-ligands are the important parameters for the study of signal transmission between cells. Recent advances in
bioanalyzer instruments have greatly simplified the measurement of the kinetics of molecular interactions.
Non-destructive and real-time monitoring the response to evaluate the parameters between antigens and antibodies can
be performed by using optical surface plasmon resonance (SPR) biosensor technology. This technology provides a
quantitative analysis that is carried out rapidly with label-free high-throughput detection using the binding curves of
antigens-antibodies. Consequently, the kinetic parameters of interaction between antigens and antibodies can be obtained.
This article presents a low cost integrated SPR-based bioanalyzer (HPSPR-6000) designed by ourselves. This
bioanalyzer is mainly composed of a biosensor TSPR1K23, a touch-screen monitor, a microprocessor PIC24F128, a
microflow cell with three channels, a clamp and a photoelectric conversion device. To obtain the kinetic parameters,
sensorgrams may be modeled using one of several binding models provided with BIAevaluation software 3.0, SensiQ or
Autolab. This allows calculation of the association rate constant (ka) and the dissociation rate constant (kd). The ratio of
ka to kd can be used to estimate the equilibrium constant. Another kind is the analysis software OriginPro, which can
process the obtained data by nonlinear fitting and then get some correlative parameters, but it can't be embedded into the
bioanalyzer, so the bioanalyzer don't support the use of OriginPro. This paper proposes a novel method to evaluate the
kinetic parameters of biomolecular interaction by using Newton Iteration Method and Least Squares Method. First, the
pseudo first order kinetic model of biomolecular interaction was established. Then the data of molecular interaction of
HBsAg and HBsAb was obtained by bioanalyzer. Finally, we used the optical SPR bioanalyzer software which was
written by ourselves to make nonlinear fit about the association and dissociation curves. The correlation coefficient
R-squared is 0.99229 and 0.99593, respectively. Furthermore, the kinetic parameters and affinity constants were
evaluated using the obtained data from the fitting results.
Monitoring system of multiple fire fighting based on computer vision
Jinlong Li,
Li Wang,
Xiaorong Gao,
et al.
Show abstract
With the high demand of fire control in spacious buildings, computer vision is playing a more and more important role.
This paper presents a new monitoring system of multiple fire fighting based on computer vision and color detection. This
system can adjust to the fire position and then extinguish the fire by itself. In this paper, the system structure, working
principle, fire orientation, hydrant's angle adjusting and system calibration are described in detail; also the design of
relevant hardware and software is introduced. At the same time, the principle and process of color detection and image
processing are given as well. The system runs well in the test, and it has high reliability, low cost, and easy nodeexpanding,
which has a bright prospect of application and popularization.
Quantitative analyses of tartaric acid based on terahertz time domain spectroscopy
Show abstract
Terahertz wave is the electromagnetic spectrum situated between microwave and infrared wave. Quantitative analysis
based on terahertz spectroscopy is very important for the application of terahertz techniques. But how to realize it is still
under study. L-tartaric acid is widely used as acidulant in beverage, and other food, such as soft drinks, wine, candy,
bread and some colloidal sweetmeats. In this paper, terahertz time-domain spectroscopy is applied to quantify the tartaric
acid. Two methods are employed to process the terahertz spectra of different samples with different content of tartaric
acid. The first one is linear regression combining correlation analysis. The second is partial least square (PLS), in which
the absorption spectra in the 0.8-1.4THz region are used to quantify the tartaric acid. To compare the performance of
these two principles, the relative error of the two methods is analyzed. For this experiment, the first method does better
than the second one. But the first method is suitable for the quantitative analysis of materials which has obvious terahertz
absorption peaks, while for material which has no obvious terahertz absorption peaks, the second one is more
appropriate.
Research on the detection system of liquid concentration base on birefringence light transmission method
Tianze Li,
Xia Zhang,
Luan Hou,
et al.
Show abstract
The characteristics of the beam transmitting in the optical fiber and the liquid medium are analyzed in this paper. On this
basis, a new type of semiconductor optical position sensitive detector is used for a receiving device, a light transmission
method of birefringence is presented,and a set of opto-electrical detection system which is applied to detect liquid
concentration is designed. The system is mainly composed of semiconductor lasers,optical systems, Psd signal
conditioning circuit, Single-chip System, A/D conversion circuit and display circuit. Through theoretical analysis and
experimental simulations, the accuracy of this system has been verified. Some main factors affecting the test results are
analyzed detailedly in this paper. The experiments show that the temperature drift and the light intensity have a very
small impact on this system. The system has some advantages, such as the simple structure, high sensitivity, good
stability, fast response time, high degree of automation, and so on. It also can achieve the real-time detection of liquid
concentration conveniently and accurately. The system can be widely applied in chemical, food, pharmacy and many
other industries. It has broad prospects of application.
Moire Ct technique and its application on laser flexible manufacture
Show abstract
In the paper, the main properties of Moire fringe, such as average effect, amplification effect, corresponding relation are
elaborated, and the principle of Moire Ct technique is represented. On the basis of main features of Moire fringe,
multidirectional Moire Ct deflection system is designed using high accuracy Ccd, grating, filter, lens, planar mirror and
optical splitter. The system has simple light path, and can be easily made into the one that has large caliber.It can analyze
multidirectional records of the probe at the same time, and can obtain clear interference patterns.The iterative technique
combined with computer chromatography algorithms is used to achieve inversion of multidirectional clear interference
patterns so that the required parameters can be acquired. Moire Ct technique is applied to laser flexible manufacture.
Produced parts are delaminated on the paper, and are stratified manufactured until they are connected to forming.
Cad/Cam system is adopted to construct Spatial three-dimensional geometric model, and the data files are formed. Then
by using the Small triangle plane, the inner and outer surfaces of the data files are discretized. Discretized parts model is
made chromatography with mathematical methods using Cam software. A series of parallel horizontal intersecting planes
are generated. The problems of filtering arrangement tangent points are solved by recombining the shape and structure
relationship among the triangular mesh. Several conclusions are presented.
New method to improve measurement accuracy of modulation transfer function
Zongxi Song,
Wei Gao,
Yan Zhou,
et al.
Show abstract
Modulation transfer function (MTF) of optical systems is often derived by taking Fourier transform (FT) of a
measured line spread function (LSF). During MTF measurement process, the measurement accuracy of MTF will
decrease as a result when LSF computed is not veracity. Based on the model constructed using the variance information
of knife-edge and skew of the knife-edge, this paper presents a new method to improve the accuracy of measurement of
MTF. The results showed that the new method can improve the accuracy of MTF to 0.01.
Research on fiber-optic gyroscope signal detection with lock-in amplifier
Xia Zhang,
Tianze Li,
Xiaojie Song,
et al.
Show abstract
Application Principles of Lock-in amplifier for the detection of weak signals are represented in the paper. Fiber optic
gyroscope ,a newest rate sensor is analysized about its' Sagnac effect, as well as the source of optical noise. The signal of
fiber optic gyroscope is submerged in the optical noise and circuit noise. Based on the signal characteristics of the fiber
optic gyroscope, a detective method with Lock-in amplifier is presented. Finally, a simulation with Matlab is done , from
the simulative results, konwing that bandwidth of equivalent noise is greatly reduced with the detective method of Lockin
amplifier. Thereby signal to noise ratio is increased, so the precision of fiber-optic gyroscope is enhanced.
Measurement of refractive indices and optical axis of a uniaxial crystal assisted by Brewster angle and reflectivity fitting techniques
J. H. Xing
Show abstract
The refractive indices along arbitrary wave vector are analyzed in a uniaxial crystal with buried optical axis. According
to the Brewster angle law, the relations between the Brewster angles of the incident p-polarized light and the two
principal refractive indices are obtained for the case that the optical axis is in the incident plane. Further, for the case of
unknown optical axis, the two principal refractive indices and the direction of optical axis can be calculated by inserting
the experimental Brewster angles into the specially derived equations. On the other hand, the functions for the
reflectivity fitting corresponding to two cases, i.e. , s-polarized light and p-polarized light, are presented. Finally, the
CaCO3 crystal has been measured both in s-polarized light and p-polarized light with a view to carefully study the effect
of incident angle on reflectivity. The accuracy of our measurement is able to reach 0.0001 without the need of any
machining process on the sample.
New method of gas concentration measurement based on continuous wave cavity ring-down
Qiuxia Yang,
Zhiquan Li
Show abstract
The basic principles of the fiber-circled cavity ring-down spectroscopy were described. A new gas measurement system
based on the fiber-circled cavity ring-down spectroscopy using continuous wave (CW) laser was designed and
constructed. And the precise research about the principles and functions of the main devices was made during the
designing process. Through analyzing the change of loss before and after filling H2S gas, know that the insertion loss
cannot exceed 0.01dB.Because gain fluctuation of erbium doped fiber amplifier(EDFA) seriously influences
measurement accuracy, a method which stabilizes the gain of EDFA was introduced, and the change of gain stability
characteristics was compared. After adding the feedback loop, the gain changes within 0.01dB, and the measuring
precision is 1ppm. The decay characteristics of H2S gas with different concentrations and the empty cavity at different
loss levels were obtained. From the experiment results, as the gas concentration increased, the decay time declined.
Influencing factors on measurement precision were analyzed, and a new method for the high accuracy gas concentration
in-situ measurement was proposed.
CCD de-noising technology based on mathematical morphology
Show abstract
This paper expatiates the theory of mathematical morphology, analyzes the characteristics of CCD (Charge Coupled
Device) noise, and introduces the traditional CCD de-noising methods. Based on this, the hological alternating hybrid
filter is designed, including the filter arithmetic design and the structural elements selection. Finally Matlab simulation
results show that this method can restrain the CCD signal shot noise, reset noise and high frequency noise better.
Research of embedded fiber Bragg grating temperature sensor system
Show abstract
In this article, an embedded fiber Bragg grating temperature sensor system is proposed and researched. The
demodulating system controls a Piezoelectric Ceramic (PZT) with sawteeth wave to scan the matching grating, then do
photoelectric conversion using a detector, and use Digital Signal Processor (DSP) to find the max intensity. Meanwhile,
use PZT drive voltage to control the central wavelength of sensor grating to demodulate. Then use the USB interface
chip to realize the communication between DSP and the host computer, and send the collected data to the host computer.
Finally, the real time temperature can be inquired and stored through the inquiring interface programmed by computer.
The result demonstrates that this experimental system has the wave addressing range from 1540 to 1565 nm and the
temperature resolution of 0.1°C.
New pseudo-random coded colored structured light technique in camera self-calibration
Show abstract
A new projecting pattern is designed based on the principle of Pseudo-Random coding in this paper, and its decoding
method is also studied according to Mathematical Morphology. Here, we initiate a new way which makes the feature
points of two adjacent windows to validate with each other. By this way, we not only assure the validity of the matching
result, but also resolve the problems of shadowing when the coded structured light is projected into the surface of the
complex 3D scene, and overlapping of some parts of coding picture because of the different shooting angles of the
camera, which results in the matching error of the feature points. The results of the experiments prove that the method
has the advantages of simplicity and high speed. Through this approach, we can realize the automatic extracting and
matching of the feature points with high accuracy.
Trinocular stereo vision method based on mesh candidates
Show abstract
One of the most interesting goals of machine vision is 3D structure recovery of the scenes. This recovery has many
applications, such as object recognition, reverse engineering, automatic cartography, autonomous robot navigation, etc.
To meet the demand of measuring the complex prototypes in reverse engineering, a trinocular stereo vision method based
on mesh candidates was proposed. After calibration of the cameras, the joint field of view can be defined in the world
coordinate system. Mesh grid is established along the coordinate axes, and the mesh nodes are considered as potential
depth data of the object surface. By similarity measure of the correspondence pairs which are projected from a certain
group of candidates, the depth data can be obtained readily. With mesh nodes optimization, the interval between the
neighboring nodes in depth direction could be designed reasonably. The potential ambiguity can be eliminated efficiently
in correspondence matching with the constraint of a third camera. The cameras can be treated as two independent pairs,
left-right and left-centre. Due to multiple peaks of the correlation values, the binocular method may not satisfy the
accuracy of the measurement. Another image pair is involved if the confidence coefficient is less than the preset
threshold. The depth is determined by the highest sum of correlation of both camera pairs. The measurement system was
simulated using 3DS MAX and Matlab software for reconstructing the surface of the object. The experimental result
proved that the trinocular vision system has good performance in depth measurement.
Technology of classification on fruit defects based on infrared thermography
Show abstract
Bruise, scratch, decay and insect pest are the most common defects in thin skin fruits. To detect these defects with the
use of infrared thermography, the mathematic model of spherical shaped fruits based on heat transfer theory is developed
and a further classification research is carried out. By using a commercial infrared thermal imaging camera, the radiation
temperature on the fruit surface of various defect tissues can be observed after thermal excitation. Both model and
experimental studies reveal that the cooling rate of specimen is related to the fruit thermal properties and fruit size, and
the logarithmic temperature is directly proportional to detection time. Bruise has a steeper cooling slope than other
defects and sound tissue, while insect pest performs poor during the fruit cooling range from 29 oC to 24 oC, this may be
related to their more cracked wax layer and higher amount of lenticels.
Speed mismatch error in the profile measurement of moving object by using TDI imaging system
Show abstract
In the projected grating phase profilometry, the CCD camera operating in time delay and integration (TDI) mode is used
to record the deformed fringe patterns. In this paper, the measuring system is consisted of a TDI CCD camera, a
projector, optical lens and a personal computer. The detected object is put on a reference plane, and a sinusoidal grating
is projected upon the object surface and reference plane at an incidence angle, respectively. The deformed fringe pattern
of the detected object is captured by the TDI CCD camera, and the deformed fringe pattern is recorded in the personal
computer for processing. A fast Fourier transform combining with a filtering method is used to extract the phase
information caused by the profile of the detected object. The phase error caused by the image distortion is researched by
simulative analysis when the moving speed mismatch between the TDI camera and the detected object is occurred.
Novel method for adjusting of single star simulator using Penta prism
De-zhi Su,
Hai-bo Liu,
Wen-liang Wang
Show abstract
Star simulator is necessary equipment for calibration and performance testing of star sensor in laboratory. A novel
method for adjustment of star simulator has been proposed in this paper. This method is based on ordinary Penta prism,
guide rail, Charge Coupled Devices (CCD) camera and sub-pixel centroid algorithm. The CCD camera is used to image
the star light replicated by the Penta prism instead of the autocollimator compared with the traditional adjustment of
collimator. The analysis shows that the limiting parallelism error of the single star simulator is less than 0.49" after
adjustment using this proposed method. It can satisfy the high accuracy adjustment of single star simulator.
High-accuracy two-dimensional small-angle measurement based on laser multiple-reflection
Show abstract
A measurement method of two-dimensional small-angle is proposed in this paper. This method is based on laser diodes,
dual-axis charge coupled devices (CCD) camera, and a series of reflections between two first-surface mirrors.
Measurement accuracy is improved as the laser beam is reflected back and forth several times between the mirrors.
Analytic ray tracing is used to model the reflected light ray so as to determine the system equations implicitly in terms of
the measured angles. A 2-dimensional high-precision tunable plane mirror is used to simulate the deflection angle. The
real-time position changes of the laser spot on the tunable plane mirror are recorded by means of CCD camera; and the
position coordinates of all laser spots in pictures are obtained by digital image processing methods and sub-pixel
weighted centroid algorithm. According to the centroid coordinate changes of laser spot, the deflection angle of the
measured object is obtained. To validate the system, a prototype is built. Calibration and stability experiments are
performed. Experimental results show that the resolution, accuracy, and measurement range are, respectively, 0.02, 0.1,
and 720 arc sec.
Potential applications of photothermal interferometric detection technique in the single-layer optical thin film system
Honggang Hao,
Jianwen Fang,
Xiangming Liu
Show abstract
The sensitive photothermal interferometric detection technique, in which an interference fringe pattern formed by
overlapping two reflected probe beams from the front and rear surfaces of the sample with two interfaces was used to
measure the photothermal signal, and its application for characterization of transparent (or partially transparent) plate
samples had been theoretically and experimentally investigated in detail. Theoretical and experimental results
demonstrated the proposed photothermal interferometric detection technique to be a sensitive photothermal method for
the study of the thermophysical properties of transparent samples. Can this method be applied to the field of single-layer
optical thin film system? We all know that a single-layer optical thin film is usually deposited on a substrate and has
three interfaces. In this paper, based on the transmission theory of Gauss-beam, the interference effect of the reflection
beams from a single layer film-substrate is studied. A theory is developed to describe the intensity profile of the
interference fringe and the corresponded modulated photothermal interferometric signal. An experiment is performed
with a ZnS-BK7 glass single-layer sample to measure the intensity distribution of the interference fringe pattern and the
photothermal signal with CW laser excitation. Agreement is obtained between the theoretical predictions and
experimental results. It shows the photothermal interferometric detection technique can be used to study the
thermophysical properties of the single-layer optical thin film system.
Design of large-size aspheric measurement system and motion accuracy analysis
Yonglu Zhu,
Yinbiao Guo,
Wei Luo,
et al.
Show abstract
A large-size four -axis aspheric measurement system is constructed in the paper. In the system, XYZ axes are driven by
linear motors and the rotation axis is based on angular encoder. In order to establish the model of motion error, the
motion error of each axis is analyzed. Then by comparing the results of first-order linear compensation and six-order
compensation with least square fit, employ the first-order linear compensation as motion accuracy compensation.
Finally, apply the measurement system to the symmetric aspheric measuring experiment. Fit the measured data of
aspherical surface and obtain the fitting deviation. The experiment results show that this measurement system can meet
the accuracy requirement of measuring large-size aspheric surface.
Fabrication 3D buried channel optical waveguide modulators on field-driven ion exchange process
Show abstract
A high electric field technique was developed to fabricate buried optical waveguide modulator on K9 optical
glass. The 80V voltage was applied on the glass to accelerate the field-driven ion exchange process by expeditiously
replacing host sodium ions in the glass with silver ions. As a result, the optical loss for optical waveguide modulator
was measured using the edge coupling technique with a 0.6328μm He-Ne laser. Loss of 0.20 dB/cm was obtained
for channel waveguides of 25μm in depth, relatively low for waveguides of such depth at red wavelength.
Study of measuring the intensity distribution of LED with lock-in amplifier
Kai Zhang,
Yujun Zhang,
Gaofang Yin,
et al.
Show abstract
By using Digital Lock-in Amplifier LI5640, the intensity distribution of LED is measured, meanwhile compared with
two other common measuring methods with the internal modulation. The structure of the research system, the transmitter
module, the optical receiving module, the research light path and Digital Lock-in Amplifier LI5640 are all introduced
and the analysis based on research results is given. It's proved that the Lock-in Amplifier is superior for weak light signal
detecting; also this research system can be the reference of correlative research designs.
Application of semiconductor laser on big dimension measuring system
Hongtao Zhang,
Xuhua Zhai,
Zhou Qu,
et al.
Show abstract
The structure and principles of an optical non-contact measuring system of large-dimension diameter were analyzed
detailed in the paper. This system can be used to measure up to the diameter of 2200 millimeters. And it also can be used
to measure the coaxiality of inner and outside of cirque. Moreover, the system can realize measure on-line parameters in
processing. The ultimate errors in measuring large-dimension diameter are less than 0.02 millimeters.
Multi-camera calibration based on openCV and multi-view registration
Show abstract
For multi-camera calibration systems, a method based on OpenCV and multi-view registration combining calibration
algorithm is proposed. First of all, using a Zhang's calibration plate (8X8 chessboard diagram) and a number of cameras
(with three industrial-grade CCD) to be 9 group images shooting from different angles, using OpenCV to calibrate the
parameters fast in the camera. Secondly, based on the corresponding relationship between each camera view, the
computation of the rotation matrix and translation matrix is formulated as a constrained optimization problem. According
to the Kuhn-Tucker theorem and the properties on the derivative of the matrix-valued function, the formulae of rotation
matrix and translation matrix are deduced by using singular value decomposition algorithm. Afterwards an iterative
method is utilized to get the entire coordinate transformation of pair-wise views, thus the precise multi-view registration
can be conveniently achieved and then can get the relative positions in them(the camera outside the
parameters).Experimental results show that the method is practical in multi-camera calibration .
Transmission characters numerical simulation of soliton based on dispersion-managed
Show abstract
Exact soliton solution of the nonlinear Schrödinger equation is achieved in the Dispersion-managed soliton system based
on a numerical averaging scheme, so the simulation results show that it can traverse great long distances stably. By the
Split-step Fourier Method, we simulate soliton evolution in the Dispersion-managed soliton system. We analyze pulse
difference between two kinds of dispersion maps, find that differences in pulse shape of one period and in pulse width
are very apparent, but the period of pulse width's change is the same.
Interference of convergent polarized light to test crystal optical surface
Show abstract
Due to properties required of optical elements, it is very important to detect the surface of non-contact object in modern
science and technology fields. There are so many methods for detection of object surface, most of which are for isotropic
and optical uniform media devices, and mainly utilize optical plane reflection of device under test to obtain. But ones for
crystal optical surface are few. The method is put forward to use interference of convergent polarized light to measure
optical surface of uniaxial and biaxial crystal in the paper. The basic principle is analyzed that is about interference of
polarized light, and the relationship is derivate that is between interference pattern of polarized light formed after
spherical light via crystal devices and crystal optical surface. The numerical computation is done by means of MATLAB.
Data processing software is programmed. The data relationship is simulated and calculated between interference pattern
of polarized light and crystal optical surface. And corresponding curve is plotted out. The testing experimental equipment
is designed and set up, which can measure the surface of uniaxial crystal (wave-plate) and biaxial crystal (KTP) whose
accuracy may come up to 0.5μm.
Analysis of the optical characteristic of particles by the discrete dipole approximation method
Show abstract
The method for measuring particles size and concentration based on the light extinction is widely used in the particles
measurement technology. In the light extinction method, the extinction efficiency factor is an important parameter. Using
the Mie theory, the extinction efficiency factor of spherical particles and equivalent-volume spheres instead of nonspherical
particles can be calculated. For analyzing the characteristics of the non-spherical particles, the discrete dipole
approximation (DDA) method is presented in this paper. The extinction efficiency factors of spherical, ellipsoid and
cylinder particles were calculated by using the DDA method under different size parameters, and compared with the
results of the equivalent-volume spheres based on Mie theory. The calculation results show that the extinction efficiency
factors of spherical particles obtained by two methods differ slightly under the whole size parameters. The extinction
efficiency factor of non-spherical particles and equivalent-volume spheres have discrepancy in evidence. The
discrepancy between them changes with the different parameters of shape and size. Furthermore, it should be noted that
when the size parameter is less than a critical size parameter, the extinction efficiency factor of non-spherical particles
obtained by two methods differ slightly, and when the size parameter is greater than a critical size parameter, the
extinction efficiency factor of non-spherical particles obtained by two methods differ greatly along with the increase of
the size parameter, the non-spherical effect on the extinction efficiency factor can not be ignored. By contrast with the
Mie theory, the DDA method has greater potential in application.
Spatio-temporal characteristic of streamer discharge detected by photoelectric method
Fan Yang,
Li Jia,
Shuhua Liu
Show abstract
In this work, we investigate streamer discharge characteristics including phase graph of discharge, hysteretic effect of
pattern evolution, dimension variation of filaments, breakdown moment of discharge etc. with a specially designed
discharge setup which has two transparent liquid electrodes and a corresponding photoelectric detection system. The
detection system is composed of lens, apertures, photomultiplier, digital camera, spectrograph, high-voltage probe, and
oscilloscope. It is found that diameter of filaments decrease as applied voltage is increased when patterns are in the
regime of spots patterns. However, diameter of filaments increases when patterns undergo a transition to a different type.
It is found that compares with applied voltage, patterns evolution exists a hysteretic effect. In addition, experiment
results indicate that patterns structure has closely relationship to temporal correlation of discharge.
Measurement of the geometric parameters of power contact wire based on binocular stereovision
Show abstract
In the electrified railway power supply system, electric locomotive obtains power from the catenary's wire through the
pantograph. Under the action of the pantograph, combined with various factors such as vibration, touch current, relative
sliding speed, load, etc, the contact wire will produce mechanical wear and electrical wear. Thus, in electrified railway
construction and daily operations, the geometric parameters such as line height, pull value, the width of wear surface
must be under real-timely and non-contact detection. On the one hand, the safe operation of electric railways will be
guaranteed; on the other hand, the wire endurance will be extended, and operating costs reduced. Based on the
characteristics of the worn wires' image signal, the binocular stereo vision technology was applied for measurement of
contact wire geometry parameters, a mathematical model of measurement of geometric parameters was derived, and the
boundaries of the wound wire abrasion-point value were extracted by means of sub-pixel edge detection method based
on the LOG operator with the least-squares fitting, thus measurements of the wire geometry parameters were realized.
Principles were demonstrated through simulation experiments, and the experimental results show that the detection
methods presented in this paper for measuring the accuracy, efficiency and convenience, etc. are close to or superior to
the traditional measurements, which has laid a good foundation for the measurement system of geometric parameters for
the contact wire of the development of binocular vision.
Finger-vein image separation algorithms and realization with MATLAB
Xiaoyan Gao,
Junshan Ma,
Jiajie Wu
Show abstract
According to the characteristics of the finger-vein image, we adopted a series of methods to enhance the contrast of the
image in order to separate the finger-vein areas from the background areas, and made prepare for the subsequent research
such as feature extraction and recognition processing . The method consists of three steps: denoising, contrast
enhancement and image binarization. In denoising, considering the relationship between gray levels in the adjacent areas
of the finger-vein image, we adopted the Gradient Inverse Weighted Smoothing method. In contrast enhancement, we
improved the conventional High Frequency Stress Filtering method and adopted a method which combined the
traditional High Frequency Stress Filtering algorithm together with the Histogram Equalization. With this method, the
contrast of the finger-vein area and the background area has been enhanced significantly. During the binarization process,
after taking the differences of the gray levels between the different areas of the finger-vein image into consideration, we
proposed a method which combined the binarization by dividing the image into several segments and the Morphological
Image Processing means. Our experiment results show that after a series of processing mentioned above by using
MATLAB, the finger-vein areas can be separated from the background areas obviously. We can get a vivid figure of the
finger-vein which provided some references for the following research such as finger-vein image feature extraction,
matching and identification.
Measurement and study of partial VOCs based on open path FTIR
Jing-jing Tong,
Wen-qing Liu,
Min-guang Gao,
et al.
Show abstract
This paper describes a long path Fourier transform infrared spectroscopy system which is used to
analyze ambient gas. Some VOCs (C2H2, C2H4) are measured with this system in laboratory. As
different VOCs has unique infrared absorbing spectrum, we retrieve VOCs concentration based on the
nonlinear least square algorithm. The result shows that the system is stable and rapid. The retrieved
concentrations are very close to real value. The system can used to monitor and research VOCs in
ambient gas.
Hyperspectral reflectance imaging for detecting citrus canker based on dual-band ratio image classification method
Jiangbo Li,
Xiuqin Rao,
Junxian Guo,
et al.
Show abstract
Citrus are one of the major fruit produced in China. Most of this production is exported to Europe for fresh consumption,
where consumers increasingly demand best quality. Citrus canker is one of the most devastating diseases that threaten
peel of most commercial citrus varieties. The aim of this research was to investigate the potential of using hyperspectral
imaging technique for detecting canker lesions on citrus fruit. Navel oranges with cankerous, normal and various
common diseased skin conditions including wind scar, thrips scarring, scale insect, dehiscent fruit, phytotoxicity,
heterochromatic stripe, and insect damage were studied. The imaging system (400-1000 nm) was established to acquire
reflectance images from samples. Region of interest (ROI) spectral feature of various diseased peel areas was analyzed
and characteristic wavebands (630, 685, and 720 nm) were extracted. The dual-band reflectance ratio (such as Q720/685)
algorithm was performed on the hyperspectral images of navel oranges for differentiating canker from normal fruit skin
and other surface diseases. The overall classification success rate was 96.84% regardless of the presence of other
confounding diseases. The presented processing approach overcame the presence of stem/navel on navel oranges that
typically has been a problematic source for false positives in the detection of defects. Because of the limited sample size,
delineation of an optimal detection scheme is beyond the scope of the current study. However, the results showed that
two-band ratio (Q685/630) along with the use of a simple threshold value segmentation method for discriminating canker
on navel oranges from other peel diseases may be feasible.
Comparison of optical surface roughness measured by stylus profiler, AFM, and white light interferometer using power spectral density
Show abstract
Surface roughness measurements were performed on fused-silica, silicon wafer, and glass-ceramic (Zerodur) by
mechanical stylus profiler, atomic force microscope (AFM), and white light interferometer (WLI). Because of the
differences of spatial frequency bandwidth of the measurement instruments surface roughnesses are actually not directly
comparable. In this study, a novel method has been developed to directly compare the roughnesses measured with
different instruments using power spectral density (PSD) function which can be calculated from the measurement data.
The RMS roughnesses were obtained by integrating areas in the overlapping regions of two or more instruments so that
roughnesses measured with different instruments could be directly compared. The agreement among RMS roughnesses
measured with the different techniques improved considerably, and the remaining differences could be explained as
being caused by surface features to which the instruments responded differently. This fruitful work also provides a great
guidance for the selection of surface roughness measurement instruments.
Design and characterization of a large-area integrating sphere uniform radiation source for calibration of satellite remote sensors
Show abstract
The large field of view (FOV) imaging radiometers performed as remote sensors are extensively used
in remote sensing and surveillance applications. The pre-launch test and radiance calibration of large
FOV imaging remote sensors have resulted in the development of calibration techniques. One of these
calibration techniques is the employment of large-area integrating sphere radiation sources as radiance
transfer standards. To meet the calibration requirements of large FOV imaging remote sensors, a
large-area integrating sphere uniform radiation source (ISURS) based on a 1600 mm diameter
internally illuminated integrating sphere with a 620 mm diameter exit port is designed and
manufactured. This large-area integrating sphere radiation source has been used for pre-launch
calibration of large FOV imaging remote sensors which fly aboard Erath-observing satellites.
Description of a system based on the DFB laser for natural gas leakage in the long optical-path of the tunnel
Show abstract
The leakage of methane and sulfureted hydrogen in the tunnel may threaten the environment, safety
and lead to damage and casualties. In this paper, a system based on the distribution feedback laser is
introduced to detect the leakage natural gas in the tunnel. The system can be used in the tunnel with the
length over 2km. In the system, two approaches, namely the direct absorption and wavelength
modulation is both adopted to acquire the concentration of methane and sulfureted hydrogen. The
results show that the remote sensing can reach up to two kilometers with the detectability of methane
2ppm and sulfureted hydrogen 20ppm respectively. This system is carried out in the Puguang Gas filed
for the first time and satisfactory results are obtained, making up the gap in such field as detecting
natural gas in domestic market.
Displacement measurement using phase joint transform correlators
Show abstract
Since joint transform correlators based on amplitude light modulator have poor light efficiency and low
cross-correlation peak, a displacement measurement method based on spatial light modulator is proposed. After the
input images were coded by phase spatial light modulator, corresponding displacement between the adjacent two
pictures could be detected through the joint transform correlator. Experiments were carried out with under-exposed
images. The experimental results showed that phase joint transform correlators had better discrimination. The proposed
technique is very effective for motion detection under circumstances of low illumination.
Step height evaluation in the vibrating condition based on microscopic interferometry
Show abstract
Microscopic interferometry can be applied in the step height evaluation with sub-nanometer vertical resolution. This
paper describes the effect of outside vibration on the evaluation process through many experiments. A micro actuator
with high accuracy is used as the simulation of outside vibration. Experiments are done on the system with different
vibration amplitudes, vibration frequencies and phase extracting algorithms. The experimental results show that different
phase extracting algorithms have different responses to the outside vibration; low frequency has a strong effect on the
measurement values when the vibration amplitude is below a threshold value; however, the effect on the step height
evaluation is small by averaging many profiles.
Study on method of data standardization in interferometric testing
Show abstract
As a rule, Interferometers are used to test the figure in the polishing phase of optical component, it could provide
advance tutor suggestion for manufacturing. It is unable to get the whole wave-front interferogram usually because
phase-shift Interferometry is sensitive to environment vibration, so the exactly interference data of the optical surface
could not be obtained. Various spatial point on the tested optical component will be given by calculation method about
arithmetic average value of equal accuracy is provied. This paper describes the testing results of optical components in
size Φ1200mm, it is proved the method could eliminate the vibration effectively and get the standardization data.
Absolute realization of low BRDF value
Show abstract
Low BRDF value is widespread used in many critical domains such as space and military fairs. These values below
0.1 Sr-1 . So the Absolute realization of these value is the most critical issue in the absolute measurement of BRDF. To
develop the Absolute value realization theory of BRDF , defining an arithmetic operators of BRDF , achieving an
absolute measurement Eq. of BRDF based on radiance. This is a new theory method to solve the realization problem of
low BRDF value. This theory method is realized on a self-designed common double orientation structure in space. By
designing an adding structure to extend the range of the measurement system and a control and processing software,
Absolute realization of low BRDF value is achieved. A material of low BRDF value is measured in this measurement
system and the spectral BRDF value are showed within different angles allover the space. All these values are below
0.4 Sr-1 . This process is a representative procedure about the measurement of low BRDF value. A corresponding
uncertainty analysis of this measurement data is given depend on the new theory of absolute realization and the
performance of the measurement system. The relative expand uncertainty of the measurement data is 0.078. This
uncertainty analysis is suitable for all measurements using the new theory of absolute realization and the corresponding
measurement system.
Compensation algorithm for optical flow vectors based on image sequences of the spot
Show abstract
A key problem in the processing of image sequences is estimating the motion between video frames, often referred
to as optical flow estimation. For the problem of the target spots loss in image sequences when aircraft's 3D attitude
parameters is measured based on optical measurement, an effective optical flow vectors compensation algorithm
from multi-frames image is proposed. First, the optical flow vectors between frames of spot target image sequences
are calculated by Lucas-Kanade algorithm, and then choose the optical flow vectors nearby the images of lost spot
target. The chosen vectors are used for estimating spot image. The compensation model of optical flow vectors is set.
Then, the lost spot target center is got by using inverse distance weighted averaging and the weight-value is the
difference of the frame count between real image and estimated image. By experiments analysis, the proper
calculating scope of this arithmetic under the expected precision is determined. This algorithm compensates the
calculation errors caused by the lost target in image sequences efficiently.
New data reduction method with local interpolation and global fitting for complementary annular subaperture interferometry
Show abstract
The objective of this paper is to describe a new data reduction method for measurement of aspheric surface shape with
complementary annular subaperture interferometric method. The approach begins with applying least-square method to
estimate the misalignments of each subaperture measurement in the local coordinates and then subtracts the nominal
aspheric prescription with the analytical formula. Each subaperture data removed misalignments and nominal surface is
represented with the corresponding function defined at discrete points. According to the complementary of the adjacent
subapertures, each normalized subaperture data is properly scaled and shifted into the global coordinates. The
combination data is further analyzed by the local interpolation and the global Zernike fitting. The experiment results
show that the performance on the reconstruction accuracy, computational efficiency and characterizing the higher spatialfrequency
information of the new reduction method is better than that of the previously reported reconstruction algorithm
with Zernike annular polynomials and matrix method.
Nonlinearity analysis of dual-frequency laser interferometer with two longitudinal modes
Show abstract
The nonlinearity error of the dual-frequency laser interferometer with two longitudinal modes and special subsequent
electrical signal processing system was studied. The expressions for the output signal pair were derived based on the
theoretical analysis when the nonlinearity existed. From the above it was given that the nonlinearity makes the
frequency-mixing output signals shift and undulate, and its main factors are the perfection degree of the optical system
adjustment and the polarization splitting degree of the polarization beam splitter. The maximum signal shift amplitude
was close to that observed on oscillograph and it could be used to estimate the perfection degree of the optical system
adjustment and determine the maximum interpolation number in the subsequent signal processing stage.
Aspheric surface testing by irradiance transport equation
Ramin Shomali,
Ahmad Darudi,
Sadollah Nasiri,
et al.
Show abstract
In this paper a method for aspheric surface testing is presented. The method is based on solving the Irradiance Transport
Equation (ITE).The accuracy of ITE normally depends on the amount of the pick to valley of the phase distribution. This
subject is investigated by a simulation procedure.
Study on paper moisture measurement method by monochromatic light sources
Changtao Mo,
Xin Du
Show abstract
We design the emission and detection optical paths of three monochromatic infrared light sources with different
wavelength. The three light sources are placed according to the different angles, so that the three kinds of
monochromatic lights are converged on the same point of the sample. Using the method, we can detect the same point
and improve the measurement accuracy. We choose the standard near-infrared monochromatic light source, so that we
can save some equipments, such as tungsten- halogen lamp, filtered wheel, collimation focalizer, electric machine, and
so on. In particular, we save the cumbersome cooling system, reduce the volume of the instrument greatly and reduce the
cost. The three monochromatic light sources are supplied by the same pulse power source, to ensure their synchronous
working.
Fiber Bragg grating sensor based on an erbium-doped fiber ring laser
Show abstract
Fiber grating (FBG) sensor using the wave-length coding has the ability of network handling, Thus arouses people's
widespread interest. The address inquiry and the signal demodulation are two key technologies which is to be solved.
Not only can the active address inquiry way increase the signal-to-noise ratio, It can have the ability to inquiry more
gratings .It is the current research hot spot.
In this paper, A fiber laser based wavelength division multiplexed sensor system with three fiber Bragg grating sensor
array as reflector of a ring-cavity fiber laser has been used. A tunable F-P filter was used to interrogate the sensors,
Wavelength-shift signal induced by the measured temperature was demodulated by an unbalanced Mach-Zehnder
interferometer. The sensitivity of the system was demonstrated to be 0.0082nm/oC,which was close to the theoretical
value.
Self-mixing interferometry based on quadrature demodulation technique for displacement measurement
Dongmei Guo,
Hui Hao,
Daofu Han
Show abstract
A new, to the best of our knowledge, method for the measurement of the micro-displacement of a remote target based on
the laser diode self-mixing interferometry(LDSMI) is presented. Quadrature demodulation technique is introduced to
improve the measurement accuracy. Phase modulation of the laser beam is obtained by an electro-optic modulator
(EOM) in the external cavity. Detection of the target's displacement can be easily achieved by sampling the interference
signal at those times which satisfied certain conditions. The major advantage of the technique is that it does not involve
any complicated calculation and insensitive to the sampling error. Experimental results show that the proposed method
can effectively improve the displacement measurement accuracy of the LDSMI system to a few nanometers.
New method for testing diffraction efficiency of AOTF
Yuanting Shen,
Shiji Yang,
Zhiping He
Show abstract
In view of characteristics of electronically tunable dispersion and staring imaging, imaging spectrometer based on
acousto-optic tunable filters (AOTF) has become one of the main technical means of extraterrestrial substance detection
all over the world. Diffraction efficiency as one of the main properties of AOTF which is used as a dispersive element in
CE-3 Infrared Imaging Spectrometer affects the system's SNR directly. Therefore, it is particularly important to test
diffraction efficiency of AOTF. There are some limitations for two testing methods existing which are the use of tungsten
halogen lamp with spectrometer and the use of fixed-wavelength laser with power meter. This paper proposes a new
method, namely the combination of tunable laser system with energy meters. Nanosecond tunable laser system produces
pulsed continuous wavelength tunable laser beams as the testing source, which can support full-band measurement.
Besides, beam splitter producing reference beams can reduce the impact of pulsed energy instability. Ratio of diffraction
energy and reference energy is considered as the diffraction part while radio frequency (RF) is on. And ratio of direct
transmission energy of AOTF and reference energy takes the place of the transmission part while RF is off. The ratio of
both is defined as diffraction efficiency. This paper describes the installation based on the new testing method mentioned.
Based on the analysis of the test results, it shows that the new testing method is a very practical testing method for
diffraction efficiency of AOTF.
Modal analysis of low-level-light aiming sight-glass based on shock testing conditions
Show abstract
Low-level-light ( LLL ) aiming sight-glass measurement technologies based on multiple circumstances testing
conditions are always concerned by military equipments manufacturers. The article puts forward the concrete steps and
method of shock circumstances testing measurement according to military optical equipments circumstances testing
standard. Using shock theory and mathematical modeling analysis, shock model of LLL aiming sight-glass based on
shock testing conditions is constructed and analyzed. Without considering resistances and under instantaneous half-sine
shock pulse, the ratio of system response amplitude and half-sine pulse peak value is related to system inherent
characteristic (inherent frequency, cycle T, etc.) and shock pulse duration D. The results indicate that given D/T⪆
10.5, / 1 max / A = , half-sine shock pulse is transmitted by 1:1. Testing device response acceleration is equal to shock
pulse peak acceleration. Testing device response is more intense under this condition. LLL aiming sight-glass structural
performance and reticle zero point moving are influenced. Optical lens offset of LLL aiming sight-glass testing parts is
impacted. Optical path parameters change and light transmission is influenced. What is more serious is that objective
lens will be broken due to shock pulse transmission.
Fabrication and test of a concave oblate ellipsoid with large relative aperture
Ke-xin Li,
Li-yin Yuan,
Pei-ming Hao
Show abstract
Fabrication and test of the concave oblate ellipsoid becomes more difficult as the mirror relative aperture gets larger. The
concave oblate ellipsoid discussed in this paper, has a very large relative aperture. Two processing methods are
introduced. One is drilling sub-mirror from the mother mirror, the other is processing sub-mirror merely. A novel method
to calculate aspheric grinding amount of the latter method is proposed. As the clear aperture and aperture decenter of the
concave oblate ellipsoid in this paper are not large, the former processing method is finally adopted. Two online
processing testing methods are proposed. One is reflective auto-collimating test; the other is refractive auto-collimating
test. As for the former, a negative power lens is applied to compensate the positive spherical aberration of the concave
oblate ellipsoid. The compensator has a negative - negative - positive configuration. As for the latter, the back surface of
the spherical is designed to be an auxiliary spherical one. Its compensator is negative- positive- positive compensator.
Besides, a high-precision plane is used to realize auto-collimating test. And the form test is selected for its online
processing testing. By optical design of the compensator and gradual aberration optimization of its alignment, the test
accuracy of the oblate ellipsoid shape can be achieved 1/10λ (632.8nm).
Research on fiber-optic sensors for methane detection based on Harmonic detection
Show abstract
In this paper, a sylstem of fiber-optic gas sensor based methane absorption spectra is studied. The system have made
great improvement and in-depth analysis in methane spectral absorption,a weak optical signal extraction and processing
and gas measurement accuracy.The system consists of light source, Photonic Crystal Fiber, air chamber, photoelectric
detectors and signal processing components and so on. According to the Lambert-Beer law, spectrum absorption
intensity is closely relate with the concentration of the gas. In order to ensure the system at a high resolution and
sensitivity,The system used distributed feedback semiconductor laser (DFBLD) as a light source .It bring useful
information of the optical signal to PIN Photodetector which then convert the optical signal to electrical signals after
optical interacting with the methane gas,then send the electrical signal to lock-in amplifier.the harmonic detection of
gas concentration was achieved by the light modulator, And then compared the harmonic component. Finally, the signal
expected was produced through the A / D converter digital in the computer.
Sensitivity of PANDA high-birefringence fiber loop mirror with temperature sensing
Ling Zhou,
Li Wang,
Shuyang Hu
Show abstract
With surrounding temperature changing, the shifting characteristics of the filtered spectrum of Panda high
birefringence loop mirror are researched, according to the birefringence laws of Panda high-birefringence
fiber and filter properties of the high-birefringence fiber loop mirror. Its sensitivity coefficient is up to
1.4219×10-9m/°C. The transmission spectrum is shifted to short wave band, and the temperature sensitivity is 20
times higher than that of the fiber grating sensors, when the temperature rises up. This temperature sensing
sensitivity is simulatated when the structural parameters are changed, such as the stress area's radius
expressed as R, the high-birefringence optical fiber's length denoted as L and the distance between the core
of the fiber and the stress area's central point marked as d. While the stress area's radius and the
high-birefringence optical fiber's length are increased, the temperature sensitivity of the Panda
high-birefringence loop mirror would become larger in its absolute value correspondingly. On the contrary,
the temperature sensitivity would descend as the distance between the core of the fiber and the stress area's
central point is increased. Furthermore, the influence on the temperature sensitivity, which is induced by
changing the internal structural parameters of the high-birefringence optical fiber, is up to 10,000 times
greater than the impacts resulted in by varying the fiber length L with the high-birefringence fiber loop
mirror.
Random-modulation CW laser ceilometer signal processing based on compound PN sequence
Jun-feng He,
Yu-jun Zhang,
Wen-qing Liu,
et al.
Show abstract
LIDAR can be well used to measure structure of atmosphere, visibility, cloud height et al. Two kinds of LIDARs have
been used to obtain the response function: micro pulse and continuous wave. A new type of LIDAR with continuouswave
operation is proposed in this paper, which is called random modulation continuous-wave (RM-CW) LIDAR based
on compound pseudo noise sequence modulation. Compared with more sophisticated LIDAR systems commonly used
for similar investigations it has several advantages, including the low peak power, ability to operate eye-safe, small size
and low price. The RM-CW technique is a typical way to recover the weak signal buried in random noise. A specific
diode laser (DL) was selected for such a compact LIDAR system because of its small size and high lasing efficiency.
Although it works reliably at a CW power level of several tens of milliwatts, this power level is smaller than that of the
pulse laser system by as much as several orders of magnitude. The generated new sequence is more suitable for the
situation that calls for the accumulation of energy by plenty of pulses to improve SNR.
Influence of non-ideal performance of lasers on displacement precision in single-grating heterodyne interferometry
Guochao Wang,
Xuedong Xie,
Shuhua Yan
Show abstract
Principle of the dual-wavelength single grating nanometer displacement measuring system, with a long range, high
precision, and good stability, is presented. As a result of the nano-level high-precision displacement measurement, the
error caused by a variety of adverse factors must be taken into account. In this paper, errors, due to the non-ideal
performance of the dual-frequency laser, including linear error caused by wavelength instability and non-linear error
caused by elliptic polarization of the laser, are mainly discussed and analyzed. On the basis of theoretical modeling, the
corresponding error formulas are derived as well. Through simulation, the limit value of linear error caused by
wavelength instability is 2nm, and on the assumption that 0.85 x T = , 1 Ty = of the polarizing beam splitter(PBS), the limit
values of nonlinear-error caused by elliptic polarization are 1.49nm, 2.99nm, 4.49nm while the non-orthogonal angle is
selected correspondingly at 1°, 2°, 3° respectively. The law of the error change is analyzed based on different values of
Tx and Ty .
Study on the test of transient ultraviolet spectrum for remote extended area sources with spectrometer
Show abstract
Spectral radiation intensity measurement at ultraviolet wavelengths is important for the material composition analysis of
transient extended area light sources. Here we developed transient ultraviolet multi-spectral spectrometer which is
utilized to measure relative spectral radiation intensity distributions of remote transient as well as steady-state extended
area light sources in the wavelength range (0.22-0.40) μm. Simultaneously the device also shows different spectral
radiation intensity distribution curve of the transient radiation source along with time changes. This spectrometer consists
of mobile collimation lens, Cassegrain imaging system, grating spectrograph, high speed data acquisition system and
computer software. Since ultraviolet spectral radiation is severely absorbed in air transmission, firstly the Cassegrain
system which has high reflectance in ultraviolet wavelength range is used to image the extended area light source onto
the entrance slit of spectrograph, in order to markedly improve the light gathering power of the device. The spectrograph
uses plane blazed grating to disperse spectrums which are focalized as the focal plane for detection by ultraviolet
response enhancing array CCD detector. Secondly, to resolve spectrum acquisition problem of nanosecond transient light
sources, we adopt CCD drive technology programmed by CPLD and fixed phasic high speed data acquisition method.
Finally, the spectral distortion of the spectrograph is reduced by using non-parametric kernel regression de-noising
algorithm and convolution algorithm in order to improve the spectral resolving power of the device. So we
experimentalize for spectral radiation intensity distributions of remote transient and steady-state extended area light
sources, then the uncertainty of measurement results is analyzed.
Design of a large area 3D surface structure measurement system
Shenghuai Wang,
Xin Li,
Yurong Chen,
et al.
Show abstract
Surface texture plays a vital role in modern engineering products. Currently surface metrology discipline is undergoing a
paradigm shift from 2D profile to 3D areal and from stochastic to structured surface characterization. Areal surface
texture measurements have greater fully functional significance parameters, better repeatability and more effectively
visual express than profile measurements. The existing white light microscopy interference measurement can be used for
the non-contact measurement of areal surface texture. However, the measurement field and lateral resolution of this
method is restricted to the numerical aperture of objective. To address this issue, a type of vertical scanning white light
interference stitching measurement system with large area and seamless has been built up in this paper. This system is
based on the compound optical microscopy system and 3D precision displacement system with large travel, nanometer
level and displacement measurement. The CCD calibration and angles calculation between CCD and level worktables
are settled depending on the measurement system itself. A non-orthogonal worktable moving strategy is used for the
seamless stitching measurement of this measurement method, which reduces the cost of stitching and enlarges the
measurement field. Therefore the problem, which the lateral resolution and the measurement filed are restricted to the
numerical aperture of objective, is solved. An automatic search and location method of fringe for white light interference
measurement based on the normalized standard deviation of gray value of interference microscopy images is proposed to
solve the problem of inefficiency for the search of interference fringe by hand.
Design of a large area 2D microscopy image measurement system
Xin Li,
Yurong Chen,
Shenghuai Wang,
et al.
Show abstract
The acquisition, identification and evaluation of microscopy image is one of the most popular and important technology
in basic research. The field and resolution of traditional microscopy are mutually restricted. For enlarging field, one
method is to design microscopy with large numerical aperture and large field by structure. But the field can't be too large
because of structure limit. The other is to stitch images. But the stitching of most microscopy is based on features of
images with a low accuracy displacement mechanism. The stitching accuracy is not high and even the stitching can't be
implemented because of discrimination errors. So a large area stitching image is difficult to obtain. To address this issue,
a type of large area, seamless and featureless microscopy image stitching measurement system has been designed in this
paper. This system is based on compound optical microscopy system and 3D precision displacement system with large
travel, nanometer level and displacement measurement. A mathematic model for CCD calibration and calculation of
angles between CCD and level worktables is established and the problem that the CCD calibration and angle
measurement of general measurement system depend on external equipments is solved. A non-orthogonal worktable
moving strategy is set up for the seamless stitching measurement of optical microscopy image measurement, which
reduces the cost of stitching and enlarges the measurement field of this method. Therefore the problem of this method,
which the lateral resolution and the measurement filed are restricted to the numerical aperture of objective, is solved.
FBG array demodulation based on optical wavelet filtering
Shiqing Qi,
Zhaoxia Wu,
Chen Wang,
et al.
Show abstract
This paper proposes a measurement system of vibration acceleration with wavelength division multiplexing and
continuous wave tunable frequency. The optical wavelet filter is designed to improve imbalanced and nonlinear optical
signal efficiently. So the optical wavelength coded absolutely is completed. Using the electrically-programmable space
modulator can filter and select frequency quickly. Besides, the signals of variation voltage produced by the computers'
filtering and selecting frequency spectrum signals implement the wavelet transform. At the same time, voltage signals
are controlled by the computer's filtering and selecting frequency spectrum signals. In the experiment, according to the
frequency spectrum characteristics of the measuring signals, the Morlet wavelet is regarded as the mother one. The
center wavelength of the wavelet function variation is controlled by computers. What's more, selecting the wavelet
transform parameter values appropriately can control the transmission spectrum of wavelet bandwidth. Then the use of
optical wavelet filters can achieve a center wavelength of FBG demodulation. Above all, this modulation method has
more advantages such as simple structure, high scanning frequency, high resolution and good linearity over the common
scanning filter.
Study on thin film thickness measurement method based on digital image processing
Show abstract
Digital Image Processing has many advantages of large image information, high precision, rich content, complex nonlinear
processing and integrated performance and so on. Application of digital image processing in the film thickness
measurement is deeply researched in this paper and the actual thickness of the SiO2 thin film is detected. In MATLAB
environment, the surface morphology of the tested film was obtained after several image processing to the interferogram
of the thin film sample which is obtained by CCD with high resolution, including reducing the noise, recognizing the
edge, spreading the region, doing two-dimensional Fourier transform and unwrapping the phase. On this basis, the thin
film thickness is obtained through extracting the section in the special place corresponding to the information of the thin
film thickness with certain step length from the 3-D topography and making data processing and analysis. The results
indicate that the thin film thickness used the method in this paper can reach good measurement accuracy with its error
less than 2 nm.
Research on stitching interferometry aspheric surface with correcting systemic aberration
Yujing Qiao,
Guihua Han
Show abstract
Sub-aperture stitching interferometry was originally used for measurement of large-diameter plane and spherical, it is a
technological means that uses small-caliber interferometer to test each parts of optical component, and then all the subaperture
data are combined or stitched together to create a map of the full surface.
Correcting adjust errors of three directions is currently stitching algorithm for realizing the stitching testing aspheric
surface. But without spatial analysis for bias errors of positioning mechanism, we can't know exactly the actual
appearance of bias errors, consequently will not be able to implement a accuracy stitching.. Because the accuracy of
individual stitching can't meet the accuracy requirements, the test result of stitching interferometry aspheric surface will
not meet requirements of accuracy due to the errors accumulation.
Correcting systemic aberration method is presented to solve the problem mentioned above. It is based on the analysis of
the actual impact appearance of location components' bias error in interferometry. The actual appearance is exactly the
same after comparing with the Seidle aberration. a correction bias errors model of stitching measure is found based on
the analysis, and it proposed an accuracy stitching measurement for quadric surface measurement. It gets the stitching
coefficients with least square fitting method, and acquires the estimate values of bias errors in sub-aperture stitching
components, and corrects the high-order systemic aberration, therefore improve the fitting accuracy in sub-apertures
overlap zone. The experiment result shows, the stitching accuracy of this stitching method is higher than traditional
stitching method.
System design of multi-function grating spectrometer
Cheng-hua Sui,
Dan-yang Xu,
Jian-ping Tong,
et al.
Show abstract
A multi-function grating spectrometer is introduced, which is composed of grating monochromator, signal receiving
units, electronic amplifiers, A/D converter, computer, matching illuminant and so on. This equipment is a complex
technique related to optics, precision machinery, electronics and computer. CCD and optical grating is used that break
the limitation of photomultiplier (PMT). The CCD can receive signals in the spatial distribution. The efficiency of full
spectrum detection is greatly raised. With the way of DMA block move and adopting high-speed A/D AD1674JN it
realizes high-speed data acquisition. The principles of system working, hardware circuit, logic of controlling are
described in detail. The spectrometer has two kinds of measurement range, the CCD can measure the spectrum wave
from 300 nm~600 nm, and the photomultiplier (PMT) can measure the spectrum wave from 200 nm~660 nm.
Controlling a Step Motor that cooperating with a deceleration system, and using the C-T optical system, in theory,
moving 0.01 nm can catch a spectral pulse, the resolution can reach 0.06 nm.
Strain sensing in fatigue test of metallic material at liquid nitrogen temperature using fiber Bragg gratings
Rong Fu,
Dongsheng Zhang,
Jieyan Li,
et al.
Show abstract
The problem about the chirp phenomenon of the FBG reflection spectrums which is usually observed in the previous
experiments has been properly solved. We found that FBG chirp phenomena at liquid nitrogen temperature are not
caused by optical mechanism, but are mainly attributed to the inhomogeneous strain distribution. The chirp phenomena
of FBGs at liquid nitrogen temperature can be eliminated by proper packaging process. A real-time strain sensing in
fatigue test of metallic material at liquid nitrogen temperature using fiber Bragg gratings was conducted. The
experimental results are significant to the applications and research of Fiber Bragg Grating in the fields of aerospace and
superconducting.
Thermal decay characteristic of fiber Bragg gratings written into Sn doped fibers loaded hydrogen and a novel encapsulation method
Jieyan Li,
Dongsheng Zhang,
Xuan Tang,
et al.
Show abstract
The high temperature sustainability of fiber Bragg gratings (FBGs) written into Sn doped fibers with hydrogen (H2)
loading is examined. Compared with ordinary H2 loaded FBGs, remarkable advantages are revealed for these FBGs as
they can sustain a temperature as high as 800°C for more than 24 hours and 900°C for 5 hours. In addition, a new
encapsulation method of the FBGs under the high temperature is also examined.
Linearity measurement for image-intensified CCD
Yuhuan Zhao,
Liwei Zhang,
Feng Yan,
et al.
Show abstract
To the characteristic of the ultraviolet CCD (UV ICCD), technique of the linearity measurement of the UV ICCD camera
is studied based on the theory of radiometry. Approach of linearity measurement is discussed, and a kind of measurement
system of the UV ICCD has been developed based on the method of neutral density filter. It is very important that the
transmittance of the filter is independent of the wavelength in the method of neutral density filter. Black metal screen
mesh with different transmittance is used in our system, and calibration of the filters' transmittance in different working
positions has been done. Meanwhile, to assure the uniform of the received radiation on the target of the detector at any
test points, an integrating sphere is placed behind the neutral filter to balance light. The whole measurement system
mainly consists of a deuterium lamp with high stabilization, the attenuation film with transmission, integrating sphere,
optical guide and electro-shift platform. Auto control is realized via special software during the test. With this
instrument, the linearity of the UV ICCD was measured. Experimental results show that the nonlinearity of the UV
ICCD under fixed-gain is less than 2% and the uncertainty of measurement system is less than 4%.
Theoretical investigation of the bending sensing characteristics for four-core fiber bragg grating
Huimei He,
Li Wang
Show abstract
Bending characteristics of four-core optical fiber Bragg gratings(MCFBGs) according to bending curvature and bending
direction is analyzed using coupled-mode theory and mechanics of materials in this paper. The simulated results show
that, bending makes the resonant wavelength of the four-core MCFBGs shift, two FBGs that in the catercorner of square
matrix cores have the same wavelength changes (▵λ1 = ▵λ3) , and (▵λ2 = ▵λ4), but have the opposition direction of
shift. The wavelength difference of two FBGs at the catercorner of the square matrix (▵λ13 = ▵λ12) is proportional to
the bending curvature. The bending sensitivity of the wavelength difference ( d(▵λ13)/ dp or ( d(▵λ24)/ dp is changed with a
different bend-directions. The orientation of the bending was determined by the arctangent of the ratio of the wavelength
difference
▵λ13/▵λ24
. The sensitivity of the wavelength difference between cores is twice to the sensitivity of the reflection
Bragg wavelength changes.
Functional design and implementation with on-line programmable technology in optical fiber communication pulse code modulation test system
Show abstract
In order to complete the functional design in the fiber optical communication pulse code modulation test system, taking
advantage of CPLD / FPGA and SOPC technology, software solutions used to design system hardware features and
control functions, thereby the whole system could attain optimisation in the logic control as well as encoding and
decoding functional designs on the motherboard, enabling this system fulfill the capacities varying from simple digital
simulation transmission modulate to the high speed fiber optical communication network information encoding and
decoding functions. Simultaneously the application of logarithmic pressure companding technique, PCM encoding and
decoding system to improve the small signal quantizing SNR(Signal-to-Noise Ratio), TP3067 adopting A rate thirteen
broken lines to carry on signal pressure companding. When the signal at a certain stage, the quantizing SNR is
invariable(as signal receives uniform quantization in this phase, therefore the quantizing SNR drops along with signal
amplititude decreasing). Test results are as follows: ideal various signal encoding and decoding system waveforms, high
performance parameters , achieve the desired designing aim, a entirely new approach to realize different kinds of
information encoding and decoding model building and implementation, saving development costs, improving design
efficiency, satisfactory actual results, stable operation.
Microscale linear birefringence measurement
Show abstract
A new method for linear birefringence measurement in micro-scale is presented. Mueller matrix is used to represent the
anisotropy properties of sample, optical fiber probe of scanning optical near-field microscopy (SNOM) and other optical
components. Two polarization modulators are used to complete the quantitative measurement. Firstly, the Mueller matrix
of the probe is calculated by analyzing the output signal without sample. Together with the matrix of the probe, the
elements of the Mueller matrix of sample could be calculated sequentially. The principle and realization method of the
scheme for linear birefringence measurement are presented. The result shows that the dual-modulator-based system can
separate the anisotropy of probe and sample, which could not be distinguished in the current scheme that using only one
polarization modulator.
Application of ZOOM-FFT for scanning-type spectrometer based on digital signal processor
Show abstract
The Fourier transform spectrometer is based on a scanning-type Michelson interferometer with two optical-beams
including reference laser and measurement light. The optical spectrum of measurement light can be obtained by colleting
the analog signal of measurement light with the sampling time-scale based on interference fringes pulse of reference
laser. The optical interferogram signal of the reference laser is converted to pulse signal, and it is subdivided into 16
times. So the sampling rate is constant only depending on frequency of reference laser and irrelative to the
scanning-motor velocity. This means the sampling rate of measurement channel signal is on a uniform time-scale.
In order to get optical spectrum, the analog signal of measurement channel should be collected and Fourier-transformed.
Digital Signal Processor (DSP) TMS320-F2812 is used. Its internal 12-bit Analog-to-Digital Converter (ADC) for
measurement channel is triggered by the 16-times pulse signal of reference laser. The DSP is used to process optical
interferogram signal with ADC sampling rate up to about 1.5MHz. The optical spectrum of measurement channel signal
is processed with 1024 points-Fast Fourier Transform (FFT) method. Then, the ZOOM-FFT is adopted. By digital
frequency-shift conversion and low-pass filter, these digital signals are processed with 1024 points-FFT once again to
improve the frequency measurement resolution. Finally, the optical spectrum of measurement channel will be
displayed on LCD with high frequency-resolution.
Null ellipsometer with multi-wavelength
Guohui Xiao,
Tianxia Lin,
Ting Yang,
et al.
Show abstract
A multi-wavelength null ellipsometer with variable incident angle has been developed recently. The ellipsometer consists
of five parts, mainly including a source set with three semiconductor lasers, a rotating component with step motor,
sample stage of variable incident angle, detector, and the system of computer control procedure and data processing
procedure. The light source set is composed of three semiconductor lasers at a wavelength of 635nm, 532nm, and 780nm
respectively and prisms used for dividing a beam of laser into two beams. An improved formula of ellipsometric
parameters (named psi and delta) has been adopted to obtain more accuracy data, as a quarter-wave plate at the
wavelength of 635nm is used as the compensator for the multi-wavelength null ellipsometer. In order to make the
instrument meet the need of ellipsometric parameters measurement of different types of substrate samples, a novel
iterative algorithm is presented. Experimental results show that the accuracy of the ellipsometric parameters can reach to
0.01°, and the precision of film thickness is 0.1nm.
Novel method to examine phase object by the use of TFT-LCD
Show abstract
A novel method of using Thin Film Transistor-Liquid Crystal Display(TFT-LCD) as phase filter in Zernike phase
contrast method is introduced. First, theoretical analysis of using TFT-LCD as programmable phase modulator instead of
conventional phase contrast plate to filter the spectrum is conducted. Then the phase modulation property curve of the
used TFT-LCD is measured which is function of gray scales in modified Mach-Zehnder interferometer, and frequency
filtering is used to eliminate interferogram's noise and the correlation method is adopted to determine the
mini-displacement of interference fringe. At last, Experiment conducted in 4F system. The result showed that the method
is effective in qualitative observation of phase distribution for a small phase object.
Analysis of absolute testing based on even-odd functions by Zernike polynomials
Show abstract
Recently most of modern absolute measurement methods rotate the flat or sphere in the interferometer. So it is very
important to exactly know how some errors such as angle rotation error, center excursion error influence the metrology.
This paper analyses these errors how to influence testing accuracy by Zernike based on Even-Odd functions. We review
traditional absolute testing of flats methods and emphasize the method of even and odd functions. The flat can be
expressed as the sum of even-odd, odd-even, even-even and odd-odd functions. Through six measurements the profile of
the flat can be calculated. We use 36 Zernike polynomials in polar coordinates to analysis the method. The polynomials
can be separated by even-odd, odd-even, even-even and odd-odd parts. We substitute polynomials for surface data and
change the arithmetic. Then we can analyze the every surface error data and exactly know the calculate accuracy of every
term through the arithmetic. The results of errors analyze by means of Matlab are shown that how the angle rotation error
to influence the accuracy. The errors analysis can also be used in other interferometer systems which have the motion of
the coordinate system.
Research on integrating sphere low-light level stress system
Show abstract
Low-light level night vision device must be assessed by light stress reliability test in the design approval testing and
production approval testing. The low-light level stress environment is the key to light stress reliability test on
Low-light level night vision device. This paper studies the actual working environment of Low-light level night
vision device from the aspects of night sky spectrum of nature light and illumination, and designs a low-light level
stress system. The system consists of double-integrating-sphere light source, light stress automatic switching device,
collimator, monitoring and control system for light stress. The system uses a total light source with radiation
structure to improve the light efficiency, solve the question of light stress consistency, achieve a typical night-day
simulation of the environment and the monitoring and control of the whole process.
Design research on higher precision optical fiber f-p sensor for detecting surface waves
Shan Ning,
Guo Heng
Show abstract
The optical fiber F-p sensor deviates from working point easily because of machining error and external factors in
practical applications. It leads to output signal attenuation and the decreasing of signal noise ratio. On this problem, the
structure of optical fiber F-p sensor is designed. The technique of dual optical wavelength stabilization is put forward and
adopted. Based on the technique, the system of low fineness optical fiber F-p sensor is designed. The mathematical
model of sensing system is established. And differential evolution algorithm is introduced to establish the optimal model
of sensing system for the first time. The structure of sensing system is simulated and optimized. The global optimization
solution can be attained in shorter run time and the error is less than 10-3. The simulation results prove that this algorithm
is proper and feasible, high efficiency and reliable. It can be applied to optimize and design the structure of optical fiber
F-p sensor. Then a higher quadrature precision sensing system is designed and machined. Experimental setup of laser
ultrasound optical fiber F-p sensing system is established for detecting surface waves. The experimental results show this
sensor can detect surface waves effectively. It has higher sensitivity and larger signal-to-noise ratio.
Analysis on the system error cause by lateral departure of the light source during Ronchi test
Bai-ping Lei,
Fan Wu
Show abstract
The Ronchi test is very useful for the testing of large aperture astronomical optical element, and will be more useful with
the achievement of testing in a quantitative way. While when it comes to application, the light source should has a
certain extent lateral departure away from the optical axis so that the image of it is apart away form itself and can be
captured. This lateral departure produces the system error in the measurement. By means of optical design software, this
paper studies the system error of the Ronchi test produced by the lateral departure of light source on the base of the
simulation and the calculation of error according to the different distances from the optical axis, and discusses the
conditions satisfied with a certain measurement requires on the foundation of the outcome. Then a system device
including the light source that can be used in the practice of the measurement is designed. This device also is very useful
for the other testing methods that need a high power and large relative diameter light source.
Vertical scanning white light interfering profilometer based on Linnik interference microscope
Shuzhen Wang,
Tiebang Xie,
Suping Chang
Show abstract
In this paper we provide a vertical scanning white light interfering profilometer based on Linnik type interference
microscope. A vertical scanning system with coarse-fine dual-stage actuators is developed, in which the coarse
positioning is performed by inclined sliding guides, AC servo motor, ballscrew and the fine positioning is performed by
parallel board flexure hinge and piezoelectric ceramic, respectively. The displacement range of the vertical scanning
system is 0~2mm and 0.4nm theoretical motion resolution can be achieved. The whole interference microscope of the
profilometer is driven by the vertical scanning system, which will eliminate the movement coupling error of vertical
direction caused by horizontal movement of 2D precision stage. The interference fringes or the focal plane can be
automatically located by moving the vertical scanning system. To eliminate the measurement errors of the profilometer
caused by incorrect positioning of the vertical scanning system, its displacement is measured in real-time by a laser
interferometer with theoretical resolution of 0.01nm. A single groove specimen with the depth of 1.26μm calibrated by
National Institute of Metrology P.R.China, MEMS device and textured steel sheet was measured to illustrate the
capabilities of the profilometer.
Research of neural network application in methane gas spectrum sensing system
Show abstract
Laser spectroscopy combined with neural network approach is a new method of monitoring coal mine gas. This research
analyses of gas concentration and predicts the process of modeling using BP neural network finds changes law of
concentration, gives the various parameters settings of neural network. Experimental results show that, BP neural
network for early warning of gas concentration is feasible. The study meets an online, real-time, fast agreement of
China's Coal Mine Gas monitoring systems.
Analysis and test of a piezoelectric deformable mirror
Dan Wang,
Chaoming Li,
Jianhong Wu
Show abstract
Adaptive optics is concerned with correcting a distorted wavefront by introducing a counter aberration into an element of
the optical system, it use widely in astronomy and there are also applications in microscopy, the writing of 3D optical bit
memory and photo-fabrication now. As an active correction element in adaptive optics, a deformable mirror can be used
to modify the phase of the beam actively. In this paper, the active wave front correction method of adaptive optics
system is studied, types and characteristics of the actuators of deformable mirror are analyzed, and mainly introduces
piezoelectric deformable mirror. According to the conclusion of theoretical analysis, if the material is selected, diameter
and thickness of the deformable mirror are given, the displacement of the deformable mirror is directly proportional to
the initial loads. A deformable mirror has been manufactured with silica. The silica plate is 100mm in diameter and
10mm in thick. 37-electrode piezoelectric actuators are selected to correct low-order aberrations. Based on the ANSYS
software, the finite element analysis model of deformable mirror is calculated. The influence of the major structural
parameters is discussed. The calculated result and the conclusion of theoretical analysis are compared. Results show that,
the endless improvement of finite element model is necessary and feasible. The value of optimization design and the
conclusion of theoretical analysis are consistent with each other. The research we do lay the foundation for the further
study with more actuators and correcting high-frequency aberration.
Research on fiber diameter automatic measurement based on image detection
Xiaogang Chen,
Yu Jiang,
Wen Shen,
et al.
Show abstract
In this paper, we present a method of Fiber Diameter Automatic Measurement(FDAM). This design is based on image
detection technology in order to provide a rapid and accurate measurement of average fiber diameter. Firstly, a
preprocessing mechanism is proposed to the sample fiber image by using improved median filtering algorithm, then we
introduce edge detection with Sobel operator to detect target fiber, finally diameter of random point and average
diameter of the fiber can be measured precisely with searching shortest path algorithm. Experiments are conducted to
prove the accuracy of the measurement, and simulations show that measurement errors caused by human factors could
be eliminated to a desirable level.
Photothermal field of multilayered spherical solids based on analogy method
Show abstract
We present a theoretical model for characterizing the thermal-wave field of solid multi-layered spherical samples
illuminated by a modulated incident beam. This theoretical model is developed by the analogous Green function method.
The specific Green's function for the multi-layered spherical structure is obtained by analogy with those of 2-layer and
3-layer structure, and the analytical expression of the thermal-wave field in the multi-layered spherical sample is
presented. The temperature field of an inhomogeneous spherical sample with incident light of arbitrary angular and/or
radial intensity distribution can be obtained by this theoretical model.
Monitor the nanometer scale thickness change of optical thin film
Yuxiao Yang,
Zhengli Dai,
Lei Wang
Show abstract
In this paper, the nanometer scale change of optical thickness is detected in real time depend upon the spectrum phase
shift of white-light interference resulted in two interface of thin film. The setup and the spectrum signal processing
software are introduced. The filter is designed through analyzing the noise features of the reflect spectrum signal
gathered from the system. It is proved that a wave-let filter is the most effective method in filter noise. Error of the
signal processing is discussed in the end. Due to this study, the software, which is used to real-time monitor the
nanometer scale thickness change of thin film, is developed. Experiments show that the system has high sensitivity, high
precision, lower cost and working on a high reliability.
Application of Zernike polynomials to test large aspheric surfaces in the fine grinding stage
Show abstract
A quantitative method in the fine grinding stage on the base of self-made test system is presented and is investigated by
the experiments is presented in the paper. The contact mechanical equipment measures aspheric vector heights directly
by a long rail and high precision grating probe. After calibrating system error and preprocessing data, the surface shape
error and wave-front aberration coefficients of aspheric mirror are obtained by Zernike polynomials wave-front fitting
the collected discrete three-dimensional data. Comparison with Hartmann sensor test method through polishing the
aspheric mirror, the accuracy of wave-front error is in approximate agreement with each other, and the accuracy can
meet the requirement of lager aperture aspheric mirror in the fine grinding stage. By experiment investigation in the
process of manufacture and test, the system can guide machining in the fine grinding stage. The measurement system
shows the advantages of low costs, operating convenience, as well as high-speed calculation.
Applications of high birefringent fiber in sensor and demodulation
Show abstract
First, the actuality of fiber sensors in homeland and abroad are outlined in this paper. And the characteristics and transfer
matrix of high birefringent fiber (HBF) are introduced. After deduction of transfer matrix of the HBF Sagnac loop
mirror, a conclusion that the frequency of optical transmissibility will not change with the wavelength change basically is
obtained, and it is proportional to the length of the HBF in the loop mirror.After the theoretical conclusion is verified by
spectrometer, the HBF Sagnac loop mirror application to sensor and demodulation are discussed. Because the frequency
of optical transmissibility is not change following the wavelength change, and it is proportional to the length of the HBF
in the loop mirror, we adopt the counting method for wavelength demodulation. Using a long HBF Sagnac loop mirror,
through the recording number of changed periods of the optical transmissibility, the wavelength variation can be judged.
This method gets high resolution, it even can be better than 0.01nm which is the higher precision of spectrometers.The
HBF is also more sensitive to temperature. If changing the temperature of the HBF in the loop mirror and keeping the
wavelength of input light invariable, the intensity of output light also changes in period. For a short HBF Sagnac loop
mirror, the period gets longer, and the range of temperature change is included in its half period. Using the short HBF
Sagnac loop mirror, we have achieved the temperature measurement. The material and devices including HBF, Pin,
circuit of amplification and Mega8 A/D converter are only used in the two methods as mentioned above. The structure is
simple and the cost is low.
Measurement system for FT-IR infrared spectral emissivity of solid surface at ultra-high temperature
Zongwei Wang,
Jingmin Dai
Show abstract
Taking account of the spectral radiation characteristics of materials in national defense, aerospace and other application
areas, especially above 2000°C, we established a new ultra-high temperature spectral emissivity measurement system.
The system covers 100~2400 °C temperature range and 2 ~ 25μm spectral range with background radiation
compensation and gas control function. Fourier transform infrared (FTIR) spectroscopy collects spectrum signal with
DTGS detector. We have tested the system non-linearity response, spectral response function and optical path
consistency, and evaluated blackbody's effective emissivity. In order to objectively evaluate results of measurement
system, we measured spectral emissivity of graphite and ultra-high temperature ceramic material ZrB2-SiC, compared the
results with literature's data and the agreement is obtained. Analyzed the factors that effects emissivity measurement
results, the standard uncertainty of spectral emissivity at 10μ;m is less than 3%.
Effects of different frequency error of mirror surface on the system imaging quality
Peiji Guo,
Xiaoyong Wang
Show abstract
Based on primary mirror having the same surface error RMS 0.025λ(λ=0.6328μm), the effect of mirror surface error of
different frequency on optical imaging system transfer function (MTF) and system energy concentration were
calculated and studied, research result shows that the surface periodic error of X direction has no effect on the MTF of X
direction, the surface periodic error of Y direction has no effect on the MTF of Y direction, and the direction of surface
periodic error almost has no effect on average MTF of all field, the average spot diameter(80% of energy) and the
average MTF in Nyquist spatial frequency of all field change with the frequency of mirror surface error periodically, but
don't increase or decrease with the frequency of mirror surface error. Research result also shows that the periodicity of
average MTF in Nyquist spatial frequency is due to that the change of MTF has periodicity in pass band with the
frequency of surface error, and the change frequency of MTF in pass band increases with the frequency of mirror surface
error, but amplitude almost is same, so the same RMS of primary mirror surface error almost has the same effect on the
performance of the imaging system, and the effect is irrelevant to the distribution frequency of surface error, the RMS of
mirror surface error decided the influence of mirror surface error to the performance of imaging system, and can be
used as a main parameter of evaluating optical surface error quality of optical imaging system.
Application of thermosonics NDT in the detection of composite materials
Yue Li,
Zhi Zeng,
Dapeng Chen,
et al.
Show abstract
Composite materials have been applied widely in a lot of fields because of their excellent performance. And the
composite materials may have some defects and be damaged in the process of manufacturing and usage, which will
result in the performance degradation of the composite structure and even a failure. Thus, it is necessary to detect the
defects of the composite materials. This paper introduced the thermosonics nondestructive testing technology, described
the fundamental principle of the technology, and gave some experimental results of two kinds of composite materials.
One of the two materials is carbon fiber foam sandwich composite material which has six pre-embedded debonding
defects, and the other one is carbon fiber laminated board with the impact damage caused by collisions with different
energies. And the testing results of the two materials by thermosonics are satisfactory. However, at present, the usual
thermal wave imaging nondestructive testing technique for detecting composite materials is based on flash pulse
excitation. In this paper, the carbon fiber laminated board was also detected by the pulsed method. And this paper further
compared these two kinds of thermal wave imaging nondestructive testing techniques and the corresponding results with
different excitation ways. Some differences could be found between these two methods by analyzing the results obtained
by different excitation ways. Furthermore, based on the differences and the other factors such as the principles and
devices of these two methods, we could summarize and know that these two methods have their respective advantages
and disadvantages and could be applied to different situations. In the actual testing process, which method will be
selected to detect the defects depends on the specific demands of the experiment and the characteristics of these two
methods. And these two methods can also be used together to detect defects for a comprehensive and effective result.
Study on viscose filament electro-optical counting system based on pulse coupled neural network algorithm
Wenchao Cheng,
Tieqiang Zhang,
Xiaolong Lin,
et al.
Show abstract
This paper disigned a practical and efficient viscose filament yarn photoelectric counting system. Have considered the
characters of viscose filament yarn that chould negative impact the system design, we changed the method of image
acquisition and applied the pulse-coupling neuron network into the detection system and finally achieved the count
results accurately.Processing accuracy of this results can meet standards of chemical fiber industry.
Research on radiometric calibration of interline transfer CCD camera based on TDI working mode
Show abstract
Interline transfer CCD camera can be designed to work in time delay and integration mode similar to TDI CCD to obtain
higher responsivity and spatial resolution under poor illumination condition. However it was found that outputs of some
pixels were much lower than others' as interline transfer CCD camera work in TDI mode in laboratory radiometric
calibration experiments. As a result photo response non-uniformity(PRNU) and signal noise ratio(SNR) of the system
turned for the worse. This phenomenon's mechanism was analyzed and improved PRNU and SNR algorithms of
interline transfer CCD camera were advanced to solve this problem. In this way TDI stage was used as a variant in
PRNU and SNR algorithms and system performance was improved observably with few influences on use. In validation
experiments the improved algorithms was applied in radiometric calibration of a camera with KAI-0340s as detector.
Results of validation experiments proved that the improved algorithms could effectively improve SNR and lower PRNU
of the system. At the same time characteristic of the system could be reflected better. As working in 16 TDI stages,
PRUN was reduced from 2.25% to 0.82% and SNR was improved about 2%.
Novel sub-pixel feature point extracting algorithm for three-dimensional measurement system with linear-structure light
Weiguang Zhang,
Nan Cao,
Haiyan Guo
Show abstract
Light strip feature point extracting is a key topic in three-dimensional measurement system with linear-structure light
developing process. A novel algorithm of sub-pixel feature point extracting is proposed. The algorithm uses Gaussian
low-pass filter to smooth light strip image, adopts edge detection and morphological algorithm to obtain segmentation
regions of light strip image. According to it's curvature properties, edge curve of a segmented region are divided into two
data sets. K-d tree algorithm is used to search for the closest point from one data set to another and build up two points
group. Based on each points group, image gray distribution of a light strip section can be obtained, and then the feature
point of one light strip section is calculated with spline interpolation algorithm. The position of extracting feature point in
light strip image is selected flexibly on the basis of measurement system parameters. Therefore, the algorithm can
effectively correct feature point extracting error for light strip image with asymmetric and incomplete property. The
results show the algorithm not only extracts the strip feature point accurately, and but also has good anti-noise and robust
performance and more extensive applicability.
New scheme of Sagnac interferometric fiber-optic current sensor insensible to mechanical vibration
Jie Mu,
Wei Zhao,
Jia Wang,
et al.
Show abstract
A new scheme of Sagnac interferometer fiber-optic current sensor insensible to mechanical vibration is presented. This
scheme eliminates the Sagnac effect, which is responsible for the sensitivity to vibration according to theoretical analysis
with Jones matrix. The improvement to the conventional Sagnac interferometer fiber-optic current sensor is achieved by
changing the structure of sensing fiber coil. This coil is fabricated by the bifilar winding technique, and it consists of one
half-wave plate embedded in the middle of sensing optical fiber and one quarter-wave plate rotated by 90 degrees in its
lower input port. Experimental results suggest that, compared to the conventional design, this new-structured Sagnac
interferometer fiber-optic current sensor has much better performance against strong mechanical vibration at
accelerations up to 20 g and frequencies from 10 to 400 Hz. Furthermore, the current measurement accuracy of the
improved fiber-optic current sensor achieves the 0.2-level at an acceleration of 20 g and a frequency of 150 Hz.
Raman shift of rare earth cobalt oxides
Weiran Wang,
Yan Zhao,
Xueying Han
Show abstract
RCoO3(R=La, Ce, Pr, Nd, Sm, Eu, Gd and Dy) perovskites prepared using the solid-state reaction
method were examined by Raman spectroscopy. The Raman active Phonons in the RCoO3 perovskites
crystallized in cubic symmetry for RCoO3 (R=La, Ce, Pr and Nd) and orthorhombic symmetry for
RCoO3 (R=Sm, Eu, Gd, and Dy) were reported. The Raman spectra of RCoO3 perovskites were
strongly dependent on the ionic radius of the rare earth elements, and the frequency shift of the most
intense modes of the orthorhombic samples were correlated with some structural parameters such as
Co-O bond distances, ionic radius of the rare earth elements and John-Teller distortion. It is clear that
Raman spectroscopy has the advantage of being very sensitive to structure distortion and oxygen
motion.
Error analysis and application of dual beam focusing method
Youhan Guo,
Hui Zhao
Show abstract
Proposed a high-precision focusing method according to practical application-- Dual Beam Focusing method. And in
accordance with geometrical optics theory introduced the basic principle of the focusing method, analyzed the error of
this method, given an conclusion of the maximum error and the error during focusing when this method applied to
telescope and microscope separately. Supported examples of applied this method to telescope system, microscope system
and camera system. This method is simple and practical with high precision.
Application of fiber Bragg grating sensing technology in long-distance detection of temperature in weapon depots
Show abstract
Incessantly long-term real-time detection of temperature is demanded in weapon depots, where the weapon
equipment is stored in, to realize the self-regulation of temperature. Long-Distance intellectualized control can be
actualized by setting sensor-net which is composed by several temperature sensors to simultaneously detect
multi-point and multi- parameter. The temperature sensors based on Fiber Bragg Grating Technology are more
suitable for long-term detection for their preponderance in high sensitivity, small volume, anti-jamming and so on.
The temperature sensing system, which is composed by several Fiber Bragg Grating sensors in one light-cable, can
accomplish Quasi-Distributed measurement and is suitable for multi-point and multi- parameter detection. Basal
principle of Fiber Bragg Grating sensing technology is expounded in the article, with a sensing system applied to the
long-distance detection of temperature in the depots is designed based on F-P Scanning Method. Besides, DSP and
FPGA are adopted pre-treat the transformed data from AD such as filter and determine threshold. The main modules
of this demodulation system such as 1550nm exact photoelectric detection module and trigonal wave voltage scan
module are designed in this paper to realize demodulation. Proved by the analysis of the testing data, the Fiber Bragg
Grating temperature sensing system, whose testing precision achieved the design purpose, has advantages of
real-time measure and long-term stability. The system, which provides guarantee to realize the auto-control of
temperature, can be generalized and will provide favorable foundation for the broad using of Fiber Bragg Grating
sensing technology in the army.
Fiber temperature measurement system by the demodulation of F-P filter
Show abstract
The laser from broadband laser source enters into the fiber Bragg grating after drilling through the coupler, if it meets the
conditions to specific wavelength, the light will be reflected in accordance with backtrack by Fiber Bragg Grating, and
enters into F-P filter. Wavelength selected by F-P filter, so various peaks of corresponding wavelength will be detected by
photoelectric detector, F-P filter measures the wavelength reflected by fiber grating sensor, and transforms the
wavelength signals into electrical signals directly. Consequently, According to empirical formula we can get the
corresponding temperature. However, when the temperature changes, that the cavity length of the F-P filter will cause
excursion and the measurements of Fiber Bragg Grating Wavelength will cause error will make error on temperature. So
before formatting the system we should get the calibration of measuring system by accidental devices. That is to say, we
get the calibration of central wavelength of the FBG. In this paper, DSP system generates scanning voltage of the F-P
filter and collects voltage signal. So we get the scanning voltage of transmission peak wavelength of the F-P filter, thus a
record of all wavelength - voltage relationship for the data can be obtained by us. This is the basis and standards that the
wavelength-voltage data is used to demodulate the wavelength of FBG.
Fluorescence detection system for hydrocarbon based on charge-coupled devices and complex programmable logic device
Zhenpu Gu,
Yingjun Guo
Show abstract
In this paper, a new method to recognize the hydrocarbon is designed based on the fluorescence analyzing technology. It
combines the fiber transducer technology and the fluorescence analyzing technology. It adopts a sphere fiber-optics
probe to realize the highly active caption and transmission of the fluorescence signal of the hydrocarbon. The chargecoupled
devices(CCD) is used to realize the high efficiency detection of the hydrocarbon fluorescence spectrum. It
adopts the data acquisition system based on the complex programmable logic device(CPLD). The CPLD is controlled by
the single chip to realize the high speed data acquisition. The experiment indicates that the system has a minimum
detecting limit of the density is 0.03ppm when the excitation wavelength is 330nm and the emission wavelength is
400nm. It has a good linear relationship in the range of 0.0- 90ppm for the density of the hydrocarbon and The linear
correlation coefficient r is 0.9986. It can realize the detection of the fluorescence of the hydrocarbon effectively.
Temperature gradients effect on surface test with high precise interferometer
Show abstract
In high precise surface testing, temperature stability and uniformity are of paramount importance to the high accuracy of
test results. Micro-temperature variation and temperature gradients not only cause the change of the air refractive index
and lead to the optical path variation in interferometer cavity, but also result in deformation of the tested surface itself,
which always brings about errors to the test results. Temperature effects on the interferometer cavity and the tested
surface are analyzed from the axial and radial directions in this letter. Temperature model of the interferometer cavity
and the tested lens are established and quantitative calculations and diagram of test results versus temperature and lens
dimension are provided. It shows that temperature gradients effect increase with the length of the interferometer and the
dimension of the tested lens. The interferometer cavity is mainly affected by radial temperature gradients while the tested
lens is mainly affected by the axial temperature gradients.
Design and fabrication of CGH for aspheric surface testing and its experimental comparison with null lens
Fazhi Li,
Jingli Zhao,
Ruigang Li,
et al.
Show abstract
Computer-generated hologram (CGH) is an effective way to compensate wavefront in null test of aspheric surfaces and
freeform surfaces. Our strategies of CGH design and fabrication for optical testing are presented, and an experiment
demonstrating the compensation results of CGH and null lens is also reported. In order to design complex CGH, software
was developed, with which we can design a CGH including three sections: main section for compensating wavefront in
null test, alignment section for adjusting the relative position between CGH and interferometer, and fiducial section for
projecting fiducial marks around the optics under test. The design result is represented in GDS II format file which could
drive a laser-direct-writer-machine to fabricate a photomask. Then, a 1:1 replication process is applied to duplicate the
patterns from photomask to a parallel optical substrate whose surface is error better than λ/60 rms. Finally, an off-axis
aspheric surface was tested with CGH and null lens respectively. The test result with CGH (0.019λ;rms) is almost the
same as the result with null lens (0.020λ rms). This experiment also demonstrated that fiducial marks projected by CGH
can be used to guide the alignment of the optics and measurement of its off-axis distance.
Three-dimensional reconstruction method on the PDE exhaust plume flow flame temperature field
Zhimin Zhang,
Xiong Wan,
Ningning Luo,
et al.
Show abstract
Pulse detonation engine (referred to as PDE) has many advantage about simple structure, high efficiency thermal [1]
cycling etc. In the future, it can be widely used in unmanned aircraft, target drone, luring the plane, the imaginary target,
target missiles, long-range missiles and other military targets. However, because the exhaust flame of PDE is
complicated [2], non-uniform temperature distribution and mutation in real time, its 3-D temperature distribution is
difficult to be measured by normal way. As a result, PDE is used in the military project need to face many difficulties
and challenges. In order to analyze and improve the working performance of PDE, deep research on the detonation
combustion process is necessary. However, its performance characteristic which is in non-steady-state, as well as high
temperature, high pressure, transient combustion characteristics put forward high demands about the flow field
parameters measurement. In this paper, the PDE exhaust flames temperature field is reconstructed based on the theory of
radiation thermometry [3] and Emission Spectral Tomography (referred to as EST) [4~6] which is one branch of Optical
CT. It can monitor the detonation wave temperature distribution out of the exhaust flames at different moments, it also
provides authentication for the numerical simulation which directs towards PDE work performance, and then it
provides the basis for improving the structure of PDE.
Research on the laboratory radiometric calibration of the thermal imager
Zifeng Lu,
Qiang Sun,
Jian Wang,
et al.
Show abstract
The radiometric calibration of the thermal imager was investigated to build the relationship between the input radiance
and the digital output to realize the temperature measurement. The radiometric calibration was implemented in the State
Key Laboratory of Applied Optics. A standard black body source was served as radiation source. The response of the
thermal imager to the input radiance was tested for different gains. The experimental results show that the average grey
level of the output imaging is linear dependence of the input radiance. Because the radiance in the receiving wave range
of the thermal imager is linear with the black body's temperature based on Planck's law of radiation, the average grey
level of the output image is also linear with the black body's temperature after fitting a curve to the experiment data
points. Then the relationship of the response and the gain was studied when the black body's temperature kept constant.
The preliminary analysis of calibration data shows that the response of the thermal imager is linear and the average grey
value of the image is directly proportion to the gain. According to the experimental results, the reference gains and the
dynamic range of temperature measurement were obtained. Finally, the uncertainty influencing the calibration results
was analyzed, the analysis shows the maximal uncertainty is 5.2%, which can meet the calibration requirement less than
10%.
Research of FBG sensor with low frequency characteristics
Show abstract
The Fiber Bragg gating (FBG) can induce the changes of minute stress outside with the movements of Bragg refected
wavelength. In addition, FBG is good at resisting interference, easy to pick off and transport and even liable to produce.
In this paper, we analyzed the response processing of strain waves in different medium such as flexible stuff, agglutinate
layers, sensors and especially Fiber Bragg gating strain sensors, learned the dynamic characteristics of strain sensors in
low frequency, and explored the application of FBG strain sensor in low frequency vibration measurement. By analyzing
the error caused by the amplitude (average value ) of FBG which is about sine wave and which is lower than the true
amplitude, we gained the reference formula for design and application of the FBG strain sensor with error range
1.6%~0.4%. Furthermore, we got the spread time and speed from the strain wave to bare fiber in theory. Because of the
time delay, we used beton materials for example to calculate the measurable frequency of strain sensor for step strain
wave. As a result, we know that the FBG strain sensors have advantages in the structure of stress and strain for high
precision, quasi-distributed digital measure, and the research results also show a guiding meaning in engineering
practice.
Influence of spatial temperature distribution on high accuracy interferometric metrology
Show abstract
We calculate the influence of temperature change on the refractive index of air, establish a model of air temperature
distribution and analyze the effect of different temperature distribution on the high accuracy interferometric metrology.
First, a revised Edlen formula is employed to acquire the relation between temperature and refractive index of air,
followed by introducing the fixed temperature gradient distribution among the spatial grid within the optical cavity
between the reference flat and the test flat of the Fizeau interferometer, accompanied by a temperature change random
function within each grid. Finally, all the rays through the air layer with different incident angles are traced by Matlab
program in order to obtain the final output position, angle and OPD for each ray. The influence of different temperature
distribution and the length of the optical cavity in on the testing accuracy can be analyzed through the RMS value that
results from repeatable rays tracing. As a result, the horizontal distribution (vertical to optical axis) has a large effect on
the testing accuracy. Thus, to realize the high accuracy figure metrology, the horizontal distribution of temperature must
be rigorously controlled as well as to shorten the length of the optical cavity to a large extent. The results from our
simulation are of great significant for the accuracy analysis of interferometric testing and the research of manufacturing a
interferometer.
Novel laser beam collimation system with Hartmann-Shack wavefront sensor as a tool
Show abstract
Collimation of laser beam plays a very important role in many aspects of applied optics including human eye aberration
measurement. In this article, a new type of method which could be used to collimate laser beam is proposed. This new
method of adjustment is characterized by objective, measurable and repeatable. On the other hand, we have also
established a complete ocular aberration measurement system which is based on the principle of Hartmann-Shack and
used Hartmann-Shack wavefront sensor as its detector. In every stage of installation of this ocular aberration system, the
degree of defocus and collimation is measured and adjusted in accordingly. Hence, the effective focal length of each
length we use is precisely measured and the collimation of laser beam is reassured. Our experiments clearly show that
this kind of new ocular aberration measurement system can effectively compensate the errors of lens and installation
deviation during the process of establishing ocular aberration measuring system. Considering this technique could be
used in other fields of area where highly calibrated parallel light beams are needed, this improvement could be very
crucial for the use of future.
The use of image differential algorithm on multi-vision system
Yang Zhao,
Xinghua Qu
Show abstract
Visual image technology has been widely used in the defects detecting, classification, automatic recognition and
measuring of industry production. However, it is hard to enhance the resolution and precision of image measurement.
The imaging quality depends on the quality of the device, such as image sensor, image acquisition card and so on.
Without increasing the device quality, a new method is presented to solve the above problems. The directional
measurement technology of high-reflective metallic surface is studied through different measurement angles. With the
multi-angle measurement results, the realization possibility will be analyzed. On this basis, we will find the method of
measuring image information by multi-angles and the proper image processing technology. It is demonstrated by
extensive experiments, compared with the single image of product, that the multiple images could be processed more
flexibly and more effectively. Therefore, the system of image vision can acquire the different level of contrast, and thus,
to much extent, higher level of resolution of image can easily be obtained. This method improves the performance of
system in robustness and accuracy.
Chirp estimation of PZT for integrating-bucket method
Show abstract
The nonlinear response of the PZT for the integrating bucket method is studied by our proposed method: discrete
chirp Fourier transform (DCFT) and maximum likelihood estimation (MLE) techniques for the integrating bucket
method. Based on the signal processing theory, the intensity obtained from CCD is processed by the DCFT and
thus nonlinear response and chirp coefficient of the PZT can be coarsely estimated. This is followed by the MLE
method, in which an iterative optimization process is complemented for accurately estimating the nonlinear
response and chirp coefficient of the PZT. One key advantage of the proposed method is that not only the nonlinear
response and chirp coefficient of the PZT can be acquired, but also initial phase acquired. Our method is tested by
simulating conditions under which a certain magnitude of nonlinearity is assumed. Nonlinear response attained by
the DCFT is compared to that attained by the MLE, and a difference between the actual nonlinear response of the
PZT and our accurate estimation by the proposed method is revealed. Several factors that will have influence on
the nonlinear response of the PZT are discussed.
New multicolor illumination system for automatic optical inspection
Guangjie Xiong,
Shuyuan Ma,
Xuejun Nie,
et al.
Show abstract
In automatic optical inspection (AOI), the illumination system affects the quality of input images and the result of image
processing in the AOI. This paper developed a new multi-color illumination system specially used in the printed circuit
board (PCB) inspection to detect a variety of defects in automated optical inspection system. The new illumination
system consists of four kinds of colors of light emitting diode (LED) arrays composed of high-density LED surface light
source. In order to detect a variety of defects, the radiation angle of the each LED array is different. The system uses a
micro-controller to control the four sets of LED arrays, after acquisition of the image, which can self-adjust the light
intensity of the illumination system based on the reference and comparison of histogram of the image in real time and
can control different color LED array respectively according to the quality of the tested image. This paper analyzed the
structural model of the illumination system and designed the control system. The experimental results show that the new
illumination system has important performances such as uniform illumination, adjustable light intensity, fast response,
lower heat and etc. The system can provide highly stable illumination for the AOI to obtain high-quality images
effectively for detect the defects of PCB, and improve the defect detection rate and reduce the defects of the false alarm
rate of AOI.
Study on intra-ocular lens aberration measurement in-air
Yuanyuan Wang,
Jiaojie Chen,
Haihua Fen,
et al.
Show abstract
In clinical ophthalmology, the wavefront aberration of human eyes is expressed by Zernike polynomial
after cataract surgery and intraocular lens implantation, the human eyes aberration will change. The
problem of objective evaluation of wavefront aberration introduced by the Intra-ocular (IOL) in-vivo
remains unsolved. This paper introduced the measurement principal of IOL wavefront aberration with
expression by Zernike polynominal in air. A Hartmann-Shack wavefront sensor system was constructed
to measure the wavefront of IOL and to get the corresponding grid patterns. After a series of computer
image processing steps, 7th order with 35 items Zernike coefficients was obtained. The IOL of 20.0D
power was measured 5 times by this system to get the spherical aberration about 6.73±0.02μm,
demonstrating the good repeatability of the system. Ten IOLs with the same 20.0D power but
difference in surface curvature were chosen for measurement. The spherical aberration observed were
in the range of 2.74μm-11.26μm. These results are valuable for the optical design of IOLs and the
aberration analysis of human eyes post-operation.
Analysis and evaluation of surface characteristics of titanium coating on diamond using combined method of wavelet and fractal
Show abstract
Nature diamond cutters are important tools to manufacture high precision optics glasses, and it is a normal method to
make such cutter that soldering diamond grain with titanium coating on tool base. However, surface characteristics of
titanium coating determine how much force that diamond grain joined with tool base. This paper introduces the research
of surface characteristics of titanium coating on diamond grain based on AFM which uses its contacting mode to get
measuring data of surface topography. Firstly, the measuring data are analyzed using 2D power spectrum algorithm to
obtain spectrum energy distribution about spatial frequency. Fractal dimension is then calculated from the radius
spectrum, and surface characteristics of titanium coating are evaluated using stationary wavelet transform where feature
separation thresholds takes as an important role based on the fractal dimension. Coating experiments show that such
method can reveal quality information of titanium coating on diamond grain comprehensively and thoroughly, thus it can
offer good experimental reference to optimizing titanium coating parameters.
Design of temperature measurement system based on two-color imaging in adaptive optics of CCD
Yong-hua Wu,
Yi-hua Hu,
Fei Jiang,
et al.
Show abstract
Optical temperature measurement technique has been widely researched in current temperature detection field. Because
the three-color thermometry based on color CCD has many disadvantages affecting temperature measurement precision,
such as the non-ideal spectral responsive bandwidth of RGB three-channel, the emissivity variance and the nonlinear
output channel, as well as the few visible light share of all the radiant energy. So a new design of temperature
measurement system based on two-color imaging in adaptive optics of CCD has been proposed in this paper. This system
was designed according to the principle of self-adaption imaging based on the feedback error signal. Especially, the
optical passive athermalisation was applied to eliminate the impact of temperature change on system image quality, and
the substrate-mask was also placed in optical path to resolve the problem of external stray light interference.
Furthermore, a new temperature measurement algorithm of two-color radiation imaging based on grayscale inversion
was deduced, which can avoid the influence of gray body assumption and non-ideal spectral response bandwidth, and
correct the interference of CCD hardware noise as well. Another fast registration algorithm of two-color image based on
wavelet transformation and mutual variance was also introduced, which has a high translation and rotation registration
precision. Eventually, the field experiment has been carried out based on this temperature measurement system. And the
result has shown that this system can calculate and display the temperature distribution of boiler flame, and have the
characteristics of high accuracy, good real-time and strong practicality.
Study on the homogeneity of fused silica blanks for lithography objective
Zhiyuan Liao,
Tingwen Xing,
Hongwei Zhu
Show abstract
With the development of the lithography technologies to create smaller features with higher NA, lower k1 values and
shorter wavelengths, homogeneity specifications for fused silica blanks continue to tighten3. Fused silica and calcium
fluoride are the only material for the DUV lithography objective. One of the difficult problems for the lithography is how
to deal with the capability of the optical material. The inhomogeneity will influence the quality of lithography objective
and is an important specification. In order to obtain relative homogeneity specifications for each fused silica blanks of
the overall lithography objective, we can iterate the lenses of the lithography objective in turn, one piece lens at a time,
which the iterated one has the same spherical gradient index, we can obtain the RMS wavefront errors of all fields after
every iterativeness. When all iterativeness is implemented, we can find the difference between design and results of
iterativeness. The degradation of the RMS wavefront errors is larger; the lens iterated is more sensitive for index.
According to the RMS wavefront errors of iterative results, we can make a conclusion that homogeneity specification for
fused silica blanks of the lithography lens is extraordinarily different, not all lens need the same homogeneity
specifications. It is known, higher homogeneity, more expensive. So we can choose the different homogeneity grade
fused silica blanks.
Monitoring fluorescence quenching of polycyclic aromatic hydrocarbons by humic acid in water using fluorescence fingerprints
Xue Xiao,
Yu-jun Zhang
Show abstract
Fluorescence measurements on selected polycyclic aromatic hydrocarbons were performed to obtain
the information about the fluorescence quenching of polycyclic aromatic hydrocarbons by humic acid.
The fluorescence properties of pyrene and fluoranthene in the presence of humic acid in water were
investigated by three dimensional excitation-emission matrix fluorescence spectroscopy. The pH
influence on the fluorescence quenching of pyrene and fluoranthene were also investigated. For both
pyrene and fluoranthene, the fluorescence quenching were dominated by static quenching processes.
According to the result of the research, the effect of humic acid on the pyrene and fluoranthene can be
calibrated in the water environment. The results show that three dimensional excitation-emission
matrix fluorescence spectroscopy has great potential for the use of in-situ measurement of polynuclear
aromatic compounds in water environment.
Research of laser cleaning technology for steam generator tubing
Suixa Hou,
Jijun Luo,
Jun Xu,
et al.
Show abstract
Surface cleaning based on the laser-induced breakdown of gas and subsequent shock wave generation can remove small
particles from solid surfaces. Accordingly, several studies in steam generator tubes of nuclear power plants were
performed to expand the cleaning capability of the process. In this work, experimental apparatus of laser cleaning was
designed in order to clean heat tubes in steam generator. The laser cleaning process is monitored by analyzing acoustic
emission signal experimentally. Experiments demonstrate that laser cleaning can remove smaller particles from the
surface of steam generator tubes better than other cleaning process. It has advantages in saving on much manpower and
material resource, and it is a good cleaning method for heat tubes, which can be real-time monitoring in laser cleaning
process of heat tubes by AE signal. As a green cleaning process, laser cleaning technology in equipment maintenance
will be a good prospect.
Research of weapon equipments health monitoring based on FBG intelligent composite materials
Show abstract
Embedding the Polymer fibers, whose limiting strain is about 10%, into the composite materials to form the intelligent
materials is researched. Encapsulating polymer fibers with epoxy resin of identical elastic modulus and embedding them
into the structures during the molding process. The Demodulating system based on F-P filter method is advanced to
analyze the shift of wavelengths with high speed DSP TMSC3206713 as data processor. Precise PIN photoelectric
cell-InGaAs-PIN-PD753, is used to transform the output of F-P filter to electricity and two high speed A/D chips
ADS1610 are used to collect the outputs of PINs. C2H2 GC for dynamical wavelength demarcation is advanced for more
precise metrical results. Strain and damage condition information is transferred to the master computer as the references
of health monitoring of weapon equipments. The primary experiments indicate that when 2 fibers with 3 gratings on each
are embedded into the material, the intensity of materials don't weaken obviously. During the molding process of high
temperature and high pressure, reflected spectrum of FBGs in hot stretching environment is analyzed through Spectrum
Instrument. Fibers do not be ruptured and their sensitivity of strain is well. F-P demodulating system realizes strain
resolution by 2με when it works at 200Hz.
Research on aircraft trailing vortex detection based on laser's multiplex information echo
Show abstract
Airfoil trailing vortex is an important reason for the crash, and vortex detection is the basic premise for the civil
aeronautics boards to make the flight measures and protect civil aviation's security. So a new method of aircraft trailing
vortex detection based on laser's multiplex information echo has been proposed in this paper. According to the classical
aerodynamics theories, the formation mechanism of the trailing vortex from the airfoil wingtip has been analyzed, and
the vortex model of Boeing 737 in the taking-off phase has also been established on the FLUENT software platform.
Combining with the unique morphological structure characteristics of trailing vortex, we have discussed the vortex's
possible impact on the frequency, amplitude and phase information of laser echo, and expounded the principle of
detecting vortex based on fusing this information variation of laser echo. In order to prove the feasibility of this detecting
technique, the field experiment of detecting the vortex of civil Boeing 737 by laser has been carried on. The experimental
result has shown that the aircraft vortex could be found really in the laser scanning area, and its diffusion characteristic
has been very similar to the previous simulation result. Therefore, this vortex detection means based on laser's multiplex
information echo was proved to be practicable relatively in this paper. It will provide the detection and identification of
aircraft's trailing vortex a new way, and have massive research value and extensive application prospect as well.
Two-beam reflectance and transmittance measurement for "Shenguang-II" facility
Jie Miao,
Pengqian Yang,
Baoqiang Zhu,
et al.
Show abstract
This presentation will propose a two-beam system of reflectance, transmittance and coating uniformity measurement,
which is specialized for the large-aperture coated mirrors used on "SG-II" (short for "Shenguang-II" ) facility. The largeaperture
(up to 400 mm × 400 mm) mirrors required for "SG-II" facility have very stringent specifications. The most
essential specifications of them are reflectance, transmittance, and coating uniformity especially for large-aperture
mirrors. The two-beam system that we introduce has two light sources, which can solve large-aperture problems quite
well. One is 1053nm infrared laser for measurement; another is 532nm visible laser for both pre-measurement and
collimation. Mirrors under test are collimated with the help of CCD in the first light path (532nm laser). Moreover, the
light beam is expanded to a suitable size, which is particularly useful for imaging pre-measurement. The second light
beam from 1053nm laser is specialized for tested high power laser wavelength requirement, without spectral resolution
problems of those photometers. It is designed for high precision single point measurement. The point-measuring path of
the full aperture can be selected by the operator, referring to the first imaging pre-measurement result. The two-beam
system we proposed has a more efficient method with the first beam. And it is also quite a good resolution to highly
accurate full-aperture measurement to large-aperture mirrors of "SG-II" facility, since it takes less time than full-aperture
scanning methods and it has better resolution and accuracy than normal imaging methods.
Research on the distribution of electric field intensity and laser damage characteristics of thin films
Yuan Li,
Jun-qi Xu,
Jun-hong Su
Show abstract
With the development of high power laser technology, laser protection attracts more and more domestic and external
researchers' attention. The study on how to increase the laser induce damage threshold (LIDT) of optical films, which is
very important, is a breakthrough to improve the capability of laser systems. In the paper, the distribution of electric field
intensity and laser damage characteristics of optical films was researched. The electric field distribution with different
thickness films were simulated by program. The electric field distribution in the film was calculated by design software
(TFCalc). Laser films were prepared by electron beam evaporation technology. The 1064 nm laser was used to
investigate laser damage properties of laser films. It was found that the distribution of electric field intensity within film
has an obvious influence on the films' anti-laser damage capability. To MgF2 single-layer film, the smaller field intensity
distribution on the thin films' air-film surface contributes to the ability of thin-film laser anti-damage. If the thin films'
structure system was designed properly and the parameters selected properly, the higher LIDT films could be obtained,
then the capability of optical system can be improved.
Analysis on properties of PCF with elliptical rings of circular air holes
Hao Rui,
Li Zhi Quan
Show abstract
In this paper, 2 novel structures of PCF containing elliptical rings of circular air holes are proposed. The first one
consists of circular air holes arranged in an inner elliptical ring and 5 outer hexagonal rings. The second one is
composed of 7 rings of circular air holes arranged in elliptical shape. Moreover, air hole diameter and hole-to-hole
pitch are altered along the distance from the center of the cross section. Properties, such as birefringence and
dispersion, of these 2 structures are numerically analyzed by using the multipole method, and the numerical results
are compared with each other. Usually, the cross section of PCFs is made up of hexagonal or rectangle rings of air
holes, and these 2 structures provide us with a novel idea to construct PCFs.
Study on inner hole testing of nozzle with small size and complex contour
Liang Zhang,
Jun-hong Su,
Li-hong Yang,
et al.
Show abstract
Testing of small size and complex contour of Nozzle, an important component affecting the engine performance, is very
difficult, particularly for the inner hole. Due to difficulty in holding, it is easy to scrap the surface of the inner hole by the
traditional contact-type detection methods. In this paper testing method of the hole is researched in details with image
stitching technology. In the testing, a serial of focused images in different depths of inner hole of nozzle are collected by
CCD camera, and compared by image focusing evaluation function, thus depth information in various locations of the
inner hole images is obtained. A full depth image, the panorama of the inner hole, is rebuilt by multi-focus image fusion
algorithm, for the image pixels corresponding to the focus altitudes are segmented. To achieve 3D reconstruction of the
inner hole, the depth information by linear interpolation is fitted to restore a precise inner hole depth information. The
results show that the inner hole of nozzle can be tested precisely with high precision which can meet the design
requirements, and the entire contour can be reconstructed by the testing method.
Coast-down time measuring system based on photoelectric method
Wei-min Zhu,
Da-yong Wang,
Fang Qi
Show abstract
Coast-down time measuring system can measure the time when speed values of Chassis Dynamometers for Automobile
Emissions Testing change from initial velocity to end velocity under different load in a given speed range. This
coast-down time will represent characters of Chassis Dynamometers for Automobile Emissions Testing such as
Dynamometer inertia weight, constant load coast-down time, variable load coast-down time, Chassis Dynamometers for
Automobile Emissions Testing can be calibrated by comparing these coast-down time with theoretical values.
Working principle of coast-down time measuring system is a photoelectric sampler of coast-down time measuring system
collects speed values information of Chassis Dynamometers for Automobile Emissions Testing. Then, determine speed
values through calculation. When the velocity is equal to initial velocity Vb value, measuring system starts a timer. When
speed reaches end velocity Ve value, measuring system stops the timer. So time interval is coast-down time from Vb to Ve.
It is obvious that accuracy of coast-down time measurement lies on whether start and end velocity can be judged
accurately and determined quickly, whether accuracy of timing can be admitted, and lies on how long these can be done.
Coast-down time measuring system with photoelectric sampler proposed in this paper involves all the above factors, as
well as improves measurement accuracy of coast-down time.
Study on a new method to measure objects polarization information
Shaojun Lu,
Jun Han,
Cunli Duan,
et al.
Show abstract
Polarization information detecting can obtain more useful knowledge of objects than traditional intensity detecting, its
merits have been paid special attention to by remote sensing especially by disguised objects detecting. At present, the
way to get objects' polarization state is achieving four intensities by mechanically rotating phase delayer to measure the
Stokes vector, which can describe objects' polarization state. Modulating coherent waves' phase difference with
electro-optical effect to achieve four intensities and inversing objects' polarization information is proposed in this paper.
This method can avoid the traditional mechanical rotation's lack of stability and reliability, which has the remarkable
advantages in space detecting and remote sensing. Experiments have been done to verify the correct and feasibility of
this approach. The key technical points in this approach are presented in the end.
Application of DBPIP to phase errors detection in coherent beam combination
Show abstract
A new phase sensing technique is used to beam combining, which is called DBPIP (the Displacement of the Brightest
Point of the Interference Pattern). DBPIP is a method of detecting piston errors between two beams based on the far-field
interference pattern. It finds the position of the brightest point of the interference pattern, and then calculates the related
piston errors. The advantage of DBPIP is very convenient using to detect the piston aberration in a coherent beam
combination (CBC) system. Theoretically, only a few iterations can compensate the piston error completely if we get the
diffractive pattern image of enough resolution. The simulation results represent that, one iteration is enough to correct the
piston error to less than λ/20; if higher accuracy is required, such as less than λ/50, two iterations is enough. Moreover,
this technique can also compensate the tilt aberrations of beams in a few iterations.
Research on far-field diffraction of cube-corner retroreflector in the satellite laser ranging system
Show abstract
Cube-corner retroreflector (CCR) has been widely used in the satellite laser ranging (SLR) systems as a cooperative
target based on its direct reflecting. It can increase the energy of laser pulse which is reflected back from the satellite,
augment the distance between the satellite and the observing station, and improve the ranging accuracy. In recent years,
CCR has become one of the essential loads of satellites for improving the satellite orbit's accuracy. CCR in a satellite
diffracts and redistributes the energy of the laser pulse, and the far-field diffraction of the CCR impacts the performance
of SLR greatly. In this paper a method for detecting the far-field diffraction characteristics of CCR quantitatively is
discussed. A measuring system is designed, some key factors, such as the incident light's collimation and the Fraunhofer
transform's accuracy are analyzed and measured. And the detected results of CCR's far-field diffraction characteristics
are compared with the numerical simulation, which can be used as a proof to demonstrate the correctness of the
experiment. At last, the CCR's far-field diffraction characteristics at different temperatures are also observed to verify
the CCR's adaptability to the space environment.
Experimental analysis of output wavefront properties for the passive Q-switched slab Nd:YAG laser
Show abstract
Many factors of intracavity perturbation will degrade the output power and beam quality for high power passive
Q-switched slab laser. In the paper, the experiment test on the output beam quality of a passive Q-switched zig-zag slab
Nd:YAG laser has been performed by adopting Hartmann-Shack (H-S) wavefront sensor and Zernike mode
reconstruction theory. In this way, the PV and RMS values of the wavefront aberration, every order zernike aberrations
can be acquired accurately, and the point spread function (PSF) of the beam and the distribution of circle energy can
also be obtained by further calculation, so the beam-quality can be known fully. The experimental results show that the
wavefront aberration of laser is mainly concentrated in the frontal 10 ranks of Zernike aberration, mainly including the
defocus A3, the low-order astigmatism A5, the coma aberration A6 and the spherical aberration A10 because of the crystal
thermal effect and the intracavity aberrated perturbation.
Research on the characteristics of composite light source pseudo-moxibustion medical apparatuses for digestive disease treatment
Show abstract
Based on the researching characteristics of heat radiation of moxa, a design method is presented that pseudo-moxibustion
medical apparatuses for gastrointestinal diseases treatment. The heat radiation spectrums of moxa measured by applying
three kinds of grating-spectrometer is presented in this paper, the result shows that the light spectrum with high medical
value ranges from 600nm to 6μm. So tungsten-halogen lamp with wide spectral range is used as light source.The output
power of light source has been controlled through adjust the duty cycle of control signal, and this changes the transmitted
peak wavelength and stimulating frequency.
Advanced fiber optic face plate quality detector design
Yang Liu,
Liping Su,
Jingxia Zhao
Show abstract
A fiber optic face plate is defined by a plurality of fibers of transparent material that are fused and compressed together
to transmit an image from one end to another end. Fiber optic face plates exhibit utility in the image intensifiers, cathoderay
tubes, and other media displays. In this paper, the design of an advanced fiber optic face plate quality detector is
presented. Modern optoelectronic imaging techniques are being used to form fiber optic plate transmission images that
are suitable for analyzing the quality parameters of fiber optic face plate. The diffusing light from a halogen lamp is
condensed by condenser lens then through a fiber optic face plate, a set of lenses are used to magnify the transmission
image, a computer controls a long linear CCD to scan the transmission image, a data grabber captures the CCD's output
data and the computer transforms the data into frame image for further analysis. Digital image processing techniques are
adopted to analyze the transmission image to obtain the required quality parameters. The image analysis software
combines the API that a company provided and programed API is used to acquire the quality parameter that a relevant
criteria required. With the long linear CCD scanning and image analysis being computerized, it accomplishes the
detection of quality parameters of fiber optic face plates automaticly. The detector can replace the manual detection
method and can be widely used for the quality detection of fiber optic face plate. Manufacturers of fiber optic face plates
can benefit from the detector for quality control.
Diaphragm-based extrinsic Fabry-Perot interferometric optical fiber pressure sensor
Qiaoyun Wang,
Wenhua Wang,
Xinsheng Jiang,
et al.
Show abstract
A new structure of diaphragm-based extrinsic Fabry-Perot interferometric (EFPI) optical fiber sensor is
presented. A double holes silica ferrule with 1.8mm outside diameter is used to align the fiber. The
Fabry-Perot (F-P) cavity is formed between the fiber end facet and inner surface of the diaphragm. The
diaphragm is attached to the top of ferrule by carbon dioxide (CO2) laser thermal fusion bonding
system. One hole of ferrule is used to align the fiber to the diaphragm and the other is used to balance
the pressure inside and outside of F-P cavity. The diameter of the sensor head is only 1.8mm. In the
pressure measurement, the pressure sensitivity of this sensor is about 25.89nm/KPa and the temperature
dependence is approximately 6nm/°C. The sensor has a linear response in the range from 0 to 3KPa.
This structure of sensor can eliminate the thermally induced inner pressure changes of F-P cavity.
Furthermore, the sensor with the temperature compensate can be used to detect the liquid level. The
fabrication of this kind sensor is simple and low cost. And the advantages of this sensor are high
sensitivity, immune to electromagnetic interference (EMI) and high temperature resistance.
Combination of skip-flat test with Ritchey-Common test for the large rectangular flat
Linchao Zhang,
Bin Xuan,
Jingjiang Xie
Show abstract
The Skip-Flat test and Ritchey-Common test are the well-known methods for large flat mirrors measurement. This paper
describes the theories of two methods. The combination of the Skip-Flat test with Ritchey-Common test is proposed.
Simulations and experiments of the combination method for testing the large rectangular flat of high aspect ratio are
shown. The results of the combination test and direct measurement are presented. In comparison of the methods, the
combination test is in good agreement with the direct measurement.
Analysis of the effects on ultra-short laser pulse beam quality caused by errors in optical systems
Hong-bo Shang,
Zhao-feng Cen,
Xiao-tong Li,
et al.
Show abstract
The quality of the ultra-short laser pulse need to be controlled in applications. In this paper, the effects on
ultra-short laser pulse beam quality caused by surface errors and assembly errors in real optical systems is analyzed in a
microscope objective system. Zernike polynomials are used to describe the surface errors and error limit is set for the tilt
and decenter in assembly. When coming to calculations, we firstly take samples from the incident laser pulse and
decompose it into different frequency components; then we use ray-tracing combing with diffraction integral from the
exit pupil to the focal plane for calculation. According to the result of the calculation and analysis, we can reasonably
control the surface errors and assembly errors in the microscope object system.
Testing aspheric surface with annular subaperture stitching method based on Hartmann Shack sensor
Hongyan Xu,
Hao Xian,
Yudong Zhang
Show abstract
Annular subaperture stitching method based on Hartmann Shack sensor for testing aspheric surface is developed in this
paper. The basic principle of the method is described. The modal wavefront reconstruction algorithm with annular
Zernike polynomials is established to get the subaperture wavefront. The stitching algorithm based on annular Zernike
polynomials is employed to get the whole-aperture wavefront. An ellipsoidal surface tested by this method. The linked
surface profile is coinciding with the whole-aperture surface profile directly tested by Zygo Interferometer, and the peakvalley
value and root mean square value of the residual wavefront between the two above wavefronts are 0.096 waves
and 0.019 waves.
Study on energy control system of film damage threshold testing by LabVIEW
Show abstract
Film damage threshold is the key parameter of anti-high-power laser. It appeared especially important to test laser
damage threshold accurately and high-effetely. And, in the process of testing film damage threshold, it's especially
significant to control laser device's exports parameters accurately and stably. Nd: YAG tune Q system controls system's
software is displayed in this paper. The software is completed with LabVIEW which is Visualization's software.
Autumnally control laser device system has been realized. Controlled parameter of laser device and its systematic
hardware composition is already explained. Main functions and characteristics of laser device control software in
damage threshold testing are shown in this paper. From experimentation, the laser device automation will not only
accelerate the laser damage threshold testing automation course, but also laser damage threshold testing efficiency will
be improved thereby.
Axial super-resolution of Gaussian beam by pupil filters
Xiaofeng Zhao,
Shasha Wang,
Zhili Zhang,
et al.
Show abstract
The general axial super-resolving theories for Gaussian beam have been investigated. The three-zone amplitude pupils
are adopted to provide specific numerical descriptions of axial super-resolution of Gaussian beam. Simulated results of
comparisons between the Gaussian beam and the Uniform amplitude beam has been presented. Furthermore, some useful
advices for the design of super-resolving pupils based on the Gaussian beam are given.
Misalignment model used in three-position absolute measurement
Show abstract
Interferometric measurement, as dominating testing methods, is widely used in the field of optical measurement.
Conventional interferometer subjects to many factors which make the measurement accuracy between λ/10 and λ/20, so
it's difficult to meet the surface testing requirements of high accuracy. Thus the three-position absolute measurement
technique is used to remove the errors which are introduced by reference surface and interferometer itself. The detailed
process and experiment of three-position absolute measurement are given. A misalignment model by rigid body theory is
presented, and the corresponding influence on interferometric measurement result is analyzed. The simulation results by
the presented model are compared with that of Zemax software. By comparing both simulation results, it confirms the
feasibility of the misalignment model.
Study on camouflage effect of targets with different characteristics under typical background
Shaoshu Gao,
Weiqi Jin,
Jihui Wang,
et al.
Show abstract
With the rapid development of infrared detecting and homing technology, it is important for us to analyze infrared
camouflage effect of ground targets to improve the survivability. In the paper, factors such as the effect of atmosphere
between detectors and targets, characteristics of targets and background and atmospheric radiance including directly
transmitted solar irradiance are taken into account in long-distance detecting. The concept of RARD (relative apparent
radiance difference) between targets and background is proposed and the camouflage effect of ground targets can be
evaluated precisely. MODTRAN 4.0 is used to analyze the camouflage effect of targets. In MODTRAN, solar zenith
angle, common background, emissivity and temperature of targets are selected to calculate RARD under certain
atmosphere condition. Simulation results show that RARD is affected by the solar zenith angle significantly in middle
infrared wavelength region, but hardly in long-wave infrared region. Under the special background, according to the
target temperature, proper coating with unchanged emissivity is selected to camouflage the target all day in long-wave
infrared region. However, for the changing background, the stealth coating with variable emissivity should be adopted.
In addition, for the same target, it is even more difficult to achieve good camouflage effect at both medium infrared band
and long wave infrared band.
Application of digital holography in temperature distribution measurement
Show abstract
The temperature variation of the testing sample can result in the density change of the surrounding air, and then the
refractive index of the air is altered accordingly. Therefore, the temperature can be obtained by detecting the phase. In
this contribution, the digital holography is presented to measure the temperature distribution, which can achieve the fullfield
and non-destructive detection. The phase distribution can be determined by applying a single fast Fourier transform
to the digital hologram. In the experiment, the LFT digital holography system is built and employed to inspect the
temperature field of an electric soldering iron. The phase images are obtained, showing the temperature distributions
around the iron with different position and time. The experimental results demonstrate the feasibility and effectiveness of
the digital holography for the temperature measurement.
Design of miniature hybrid target recognition system with combination of FPGA+DSP
Shishang Luo,
Xiujian Li
Show abstract
With advantages of flexibility, high bandwidth, high spatial resolution and high-speed parallel operation, the
opto-electronic hybrid target recognition system can be applied in many civil and military areas, such as video
surveillance, intelligent navigation and robot vision. A miniature opto-electronic hybrid target recognition
system based on FPGA+DSP is designed, which only employs single Fourier lens and with a focal length. With
the precise timing control of the FPGA and images pretreatment of the DSP, the system performs both Fourier
transform and inverse Fourier transform with all optical process, which can improve recognition speed and
reduce the system volume remarkably. We analyzed the system performance, and a method to achieve scale
invariant pattern recognition was proposed on the basis of lots of experiments.
A novel gas sensor used for C[sub]2[/sub]H[sub]2[/sub] trace detection in power transformer
Show abstract
A novel gas sensor has been presented using tunable diode laser absorption spectroscopy (TDLAS) technique for
incipient faults monitoring in power transformer. In this sensor, near infrared distribute feedback laser diode (DFB
LD) is used as light source, a 0.5m short optical path cell is used as absorbing cell , two InGaAs PIN photo diodes
are used as detector. Applying TDLAS technique and Wavelength modulation spectroscopy (WMS) technique, and
combining with ARM9 S3C2140 processor controlling, the system has been implemented compact and flexible. The
concentration monitoring based on TDLAS method is obtained in situ and in real time, and the detected precision is
below ppm degree, which can meet the requirement for power transformer incipient faults.
Non-contact high precision measurement of surface form tolerances and central thickness for optical elements
Show abstract
The traditional contact measuring methods could not satisfy the current optical elements measuring requirements. Noncontact
high precision measuring theory, principle and instrument of the surface form tolerances and central thickness for
optical elements were studied in the paper. In comparison with other types of interferometers, such as Twyman-Green
and Mach-Zehnder, a Fizeau interferometer has the advantages of having fewer optical components, greater accuracy,
and is easier to use. Some relations among the 3/A(B/C), POWER/PV and N/ΔN were studied. The PV with POWER
removed can be the reference number of ΔN. The chromatic longitudinal aberration of a special optical probe can be
used for non-contanct central thickness measurement.
Three-position method for leveling optical surface automatically based on 2D PSD
Show abstract
A new method for leveling optical surface automatically based on 2D Position Sensitive Detector
(PSD) was developed and applied in Total Integrated Scatterometer for qualification of superpolished
substrates. For light path in the method, incident laser beam is required to be reflected by the sample
surface onto PSD, which provides light spot position on photosurface at resolution of 5 μm. Firstly, 2D
motorized translation stages under the sample translate it along the two orthogonal translation axes by a
distance, and PSD yields correspondingly three positions, from which the sample surface's attitude
expressed as analytic equation and normal vector is derived. Secondly, 2D motorized goniometers
between the sample and translation stages rotate orderly in each direction of translation axes by angles
computed according to rotation transformation to make the sample surface's normal vector vertical.
Finally flyback translation is performed to verify the spot on PSD photosurface yields no displacement
and the sample surface is level.
In the paper, formulas from three positions to the surface's analytic equation and rotation angles are
deduced in detail. Performance and error analysis according to the scatterometer's actual dimension
shows that the leveling system's adjustable range is ±1.7° and the resolution of two translation axes is
separately 21" and 0.5°. Experiment results show that the three-position leveling method's precision is
less than 0.1°.
Study on influencing factors of measuring precision of OTF measurement instrument
Kan Zhao,
Junhe Meng
Show abstract
Optical Transfer Function(OTF) Measurement is well known as the more accurate and more comprehensive method that
is used in evaluating the imaging quality of optical systems. Nowadays almost all optical companies and national
standard institutes use the OTF measurement instruments as the most reliable image evaluation systems. But in the
actually measuring process, it is frequent that the measuring results of the same sample are variable by using different
instruments. The reason is that the subsystems of the OTF measurement instrument have inherent errors, which made the
different OTF measurement instruments have dissimilar measuring precisions. In addition, temperature and the resulting
thermal expansion dynamics of the mechanical set-up become factors limiting the performance of OTF measurement
instruments. In this paper, the fundamental theories of OTF measurement instrument were introduced, including its
mathematical model, measuring principle, basic structure and so on. Then the influences of inherent errors of subsystems
and the thermal expansion dynamics of the mechanical set-up on OTF measurement instrument were also discussed in
detail. Based on the analyses of this paper, it is obvious that the OTF value measured by OTF measurement instrument
can only be treated as a sort of relative benchmark. However, this relative benchmark can also produces feedback on the
performances of optical systems by rule and line in time. And it always has the main effect in guiding the design,
machining, assembly, debugging and any other process of production.
CCD non-uniformity effects on position accuracy of star sensor
Jia-li Liao,
Hai-bo Liu,
Hui Jia,
et al.
Show abstract
The photoelectric response and the character of the CCD non-uniformity are analyzed in this paper. Based on the
analysis, the model of CCD non-uniformity effects on position accuracy of the star spot is established. A correction
method based on the least square estimation is used to correct the CCD photoelectric response non-uniformity. The effect
of CCD non-uniformity on position accuracy of star sensor before and after the compensation is simulated. The results
show that the position accuracy of the star sensor has been improved obviously after compensation. In addition, the
differences of the photo response non-uniformity and the mean photo response coefficient do not influence the results of
the compensation according the analysis.
Beam wavefront and farfield control for ICF laser driver
Wanjun Dai,
Wu Deng,
Xin Zhang,
et al.
Show abstract
Five main problems of beam wavefront and farfield control in ICF laser driver are synthetically discussed, including
control requirements, beam propagation principle, distortions source control, system design and adjustment
optimization, active wavefront correction technology. We demonstrate that beam can be propagated well and the
divergence angle of the TIL pulses can be improved to less than 60μrad with solving these problems, which meets
the requirements of TIL. The results can provide theoretical and experimental support for wavefront and farfield
control designing requirements of the next large scale ICF driver.
Phase-stepping method for whole-field photoelastic stress analysis using plane polariscope setup
Show abstract
A new six-step phase shifting method is presented in this paper to determine the phase retardation for whole-field
photoelastic stress analysis in optical glass based on the plane polariscope setup. This new phase stepping strategy is of no
quarter wave plate errors and with less intensity variations of emerging light. By this method, it's not necessary to
determine the isoclinic angles in advance when measuring the phase retardations, so the data processing will be simplified
and the isoclinic angle errors will cause no influnces on the measurement. A plane polariscope is setup including a LED
array light source, rotatable dichroic polymer film polarizer and analyser, a digital CCD camera and image grab system.
Two mica waveplates with known phase retardances are measured, and the experimental results agree well with the those
values. This method is expected to be used for the stress induced birefringence test in optical glass.
Study on ultra-fast single photon counting spectrometer based on PCI
Show abstract
The time-correlated single photon counting spectrometer developed uses PCI bus technology. We developed the ultrafast
data acquisition card based on PCI, replace multi-channel analyzer primary. The system theory and design of the
spectrometer are presented in detail, and the process of operation is introduced with the integration of the system. Many
standard samples have been measured and the data have been analyzed and contrasted. Experimental results show that
the spectrometer, s sensitive is single photon counting, and fluorescence life-span and time resolution is picosecond level.
And the instrument could measure time-resolved spectroscopy.
Fiber methane gas detector based on harmonic detection and application in ventilation air methane power generation
Yanfang Li,
Yubin Wei,
Ying Shang,
et al.
Show abstract
A fiber methane detector based on spectrum absorption is reported. The methane monitor use a distributed feedback
diode lasers(DFB) which is near infrared spectroscopy as the optic source, we realized online harmonic detection of the
methane. The advantages of this detector include high precision, elimination of interference from humidity and other
gases as well as long recalibration cycle. The detection of CH4 is very important in the methane power generation.
Especially the detection of the tail gas with high temperature is the dependence to judge the generator. In this paper, we
give some data witch gained from the local of methane power generation. The data reach an agreement with the
measurements of the sensor using in mine. And the detector has the function of self reference, so the detector is more
depended. This proved that the fiber methane detector can meet the needs of the generator. It have some contribution to
the production safety of the mine and the energy saving and emission reduction and the environmental protection.
Strain-temperature monitor of high speed railway switch by fiber Bragg grating gauges
Weilai Li,
Xiaomei Huang,
Jian Cheng,
et al.
Show abstract
On the 350km/h high speed railway there is a seamless track switch on a bridge. 32 Fiber Bragg Grating (FGB) gauges
are used along the neutral line of the tracks to monitor the strain generated by thermal, geological and vibrational factors,
and these FBG strain gauges have the function of strain expansion. Meanwhile other 6 FBG sensors are used to measure
the temperature for strain compensating purpose. The Finite Element Analysis method is used to analyze the special
shape of the gauges. A testing unit was used to test the FBG gauges and bare FBG on the track samples under
measurable pressure and tension. The fixing and encapsulating technology of FBG gauges on the surface of the track and
to protect the fiber cable to survive in the harsh conditions are discussed. The strain status of switch tracks could be
obtained by processing the data from FBG strain gauges and FBG temperature sensors. The results of measurement
showed that in 9 days, the strain in the track shifted 350 με, and the strain curves closely correlated with the temperature
curves.
Direct absorption measurement of ambient nitric oxide based on room-temperature pulsed quantum cascade laser
Yuan-yuan Tang,
Wen-Qing Liu,
Rui-Feng Kan,
et al.
Show abstract
The Mid-infrared lasers are very effective for high-sensitive trace gas detection for the fundamental
absorption lines of most gases. The quantum cascade (QC) laser, with the advantages of high power,
wide tuning range and room-temperature operating conditions, is one of the ideal mid-IR sources
developed in these years. The technology combing the room-temperature pulsed quantum cascade laser
and the long-path multipass absorption cell can satisfy the need for the sensitivity, selectivity and rapid
response. A set of experimental apparatus for the direct absorption measurement of ambient nitric
oxide(NO) with the room-temperature pulsed QC laser was presented. With this system a NO
concentration of 188ppb was demonstrated, along with an estimated detection limit of 4ppb. The results
show that this experimental apparatus can fulfill the detection of NO concentration in ambient air.
Determination of the optical constants of thin films by means of transmission spectra and curve fitting
Show abstract
A method to calculate the optical constants (refractive index n, film thickness d and extinction coefficient k) of
double-coated thin film by use of transmission spectrum is described in this paper. For double-coated glass films, the
relationship between T, λ, n, k and d is analyzed theoretically. Then the method to determine these optical parameters by
curve fitting is introduced. Several samples with different Sn concentrations have been prepared. According to the
method mentioned above, we calculate the coefficients of Sn-doped SiO2 films produced by Sol-gel method. Two kinds
of expressions for the refractive index n are introduced. One is Cauthy model. The other is defined as Polynomial model.
Also the expressions for k are given similarly. At last, the experimental curves are fitted according to the transmittance
formula. Results show that the refractive index becomes larger with the increase of Sn in the compound. Also, it turns out
that the refractive index decreases when the wavelength increases. This method combines the extreme point method with
the whole transmission spectra fitting method. This can improve the fitting accuracy.
Feedback compensation method for angular displacement measurement based on a Fabry-Perot interferometer
Caini Zhang,
Xiaopeng Zhang
Show abstract
In this paper, we describe a new method for wide range and high-precision angular displacement measurement. In this
method, the system real-time detects the testing object rotation, obtains the wide range angular displacement through
accumulating its micro angular displacement. By adjusting the reflector, the beams reflected from the testing object
normal incidence to the FP plate, before it is rotated. When the testing object is rotated, the system real-time gives the
testing object micro angular displacement and the rotated angle of the Fabry-Perot (FP) plate. The testing object micro
angular displacement is used for accumulating. The FP plate is real-time rotated under the control of the feedback system
to compensate the initial angle's loss of incidence on the FP plate, and makes the beams reflected from the testing object
normal incidence to the FP plate all the time. Each measurement accuracy of 10-8 is abstained by use of the sinusoidal
phase-modulating interferometry [1, 2]. So that, the wide range and high-precision angular displacement measurement is
obtained.
Modulation transfer function measurement of sampled imaging systems in field test
Le Yang,
Qiang Sun,
Jian Wang,
et al.
Show abstract
A digital mirror device (DMD) based light projector was developed as the target generator in modulation transfer
function (MTF) measurement. In order to overcome the sampling-scene phase effect in MTF measurement of sampled
imaging systems, a method using random targets is introduced to yield a phase-averaged MTF. The main potential
problem of implementing this method is the fact that the stationary assumption of the random targets may be vitiated in
practical measurement, especially in field test due to the ill condition. We provide an efficient model-independent way of
analyzing and isolating the spectral contents arising from these additional contributions to MTF measurement.
Algorithms with adaptive parameter selection were also developed for spectral estimation of the test image in order to
overcome the challenge brought by the size limit of the test matrices for one certain field of view derived from the
isoplantic region. The MTF measurement of a CCD video imager is used to demonstrate the measurement technique and
illustrate the benefits over other methods. In order to validate the results, comparisons have been made between MTF
measurements of imager implemented using this method and bar target direct measurements.
Measurement and analysis of surface profiles by inverse scattering method
Shu-yan Chen,
Xin-jun Xu
Show abstract
Evaluation and measurement of surface profiles are very important especially to short wavelength optical research. A
linear system treatment of short-wavelength surface scattering theory is introduced, and based on this, a new inverse
scattering mathematical model of soft X-ray grazing incidence optics is established. By using these scattered light
distributions of super-smooth surfaces measured by a soft X-ray reflectometer, the surface profiles of super-smooth
surfaces are computed by means of inverse scattering mathematical model of soft X-ray grazing incidence optics. The
calculating results are in accordance with those measured by WYKO. It can be concluded that the soft X-ray grazing
incidence optical scattering method can calculate micro-roughness and surface auto correlation function of smooth
surface accurately, and can give optical surface profiles intuitively.
Analysis of closed fringe patterns for aspheric surface measurement
Liang Nie,
Baoyuan Liu,
Jun Han,
et al.
Show abstract
The closed fringe patterns analysis is difficult to handle, especially in interferometer for aspheric surface measurement.
Two-dimensional fast Fourier transform (FFT) algorithm is proposed to extract interferogram phase in this paper. The
principle and process of FFT method is described and the computer simulation proves its validity. Some key techniques
are researched, such as the filter design and the elimination of prejudicial error. In order to eliminate the effect of the
abrupt change in the wrapped phase map, the rectangular low-pass filters with different directions and image stitching
technology are applied. To reduce spectral leakage, filter design and determination method of phase mutation position
are discussed. The unwrapped phase distribution is got by the unweighted least-squares phase unwrapping algorithm and
the error of spherical figure is derived from the fitting method of Zernike polynomials. The simulation results show that
the method is up to high precision. The methods are used to treat the aspheric surface measurement in experiment. The
results of processing the aspheric surface interferograms in a zone-plate interferometer indicate that the methods have
achieved worthy measurement precision and have great development potential.
Research on the application of lidar extinction coefficient inversion method
Peng Liu,
He Chen
Show abstract
As the extinction coefficient is related to directly many atmosphere character, it is important to get extinction coefficient
of atmosphere. Lidar has been proven to be a kind of useful method for remotely sensing the optical properties of
atmospheric aerosols. The relationship between the Mie backscattering signal intensity and the detection range can be
accurately achieved by Mie Lidar, and the atmospheric aerosol extinction coefficient can be retrieved from the
backscattering signal. In this paper, a practical 532nm system of Lidar on the basis of MIE and Raman scattering, which
consists of laser transmitter, signal receiver and data processing system, is presented and some experimental results have
been gathered. In last some years, there are many data processing methods in inversion of aerosol extinction coefficient.
Among these algorithms, Fernald inversion method is adopted abroad to obtain optical parameters in inhomogeneous
atmosphere. This paper discusses the data processing method gives the extinction coefficient profile. At last, the effect of
some estimated parameters is discussed.
Photogrammetry research for FAST eleven-meter reflector panel surface shape measurement
Rongwei Zhou,
Lichun Zhu,
Weimin Li,
et al.
Show abstract
In order to design and manufacture the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) active reflector
measuring equipment, measurement on each reflector panel surface shape was presented, static measurement of the
whole neutral spherical network of nodes was performed, real-time dynamic measurement at the cable network dynamic
deformation was undertaken. In the implementation process of the FAST, reflector panel surface shape detection was
completed before eleven-meter reflector panel installation. Binocular vision system was constructed based on the method
of binocular stereo vision in machine vision, eleven-meter reflector panel surface shape was measured with
photogrammetry method. Cameras were calibrated with the feature points. Under the linearity camera model, the lighting
spot array was used as calibration standard pattern, and the intrinsic and extrinsic parameters were acquired. The images
were collected for digital image processing and analyzing with two cameras, feature points were extracted with the
detection algorithm of characteristic points, and those characteristic points were matched based on epipolar constraint
method. Three-dimensional reconstruction coordinates of feature points were analyzed and reflective panel surface shape
structure was established by curve and surface fitting method. The error of reflector panel surface shape was calculated
to realize automatic measurement on reflector panel surface shape. The results show that unit reflector panel surface
inspection accuracy was 2.30mm, within the standard deviation error of 5.00mm. Compared with the requirement of
reflector panel machining precision, photogrammetry has fine precision and operation feasibility on eleven-meter
reflector panel surface shape measurement for FAST.
Fiber optic TDLAS-based multi-gas remote detection system for mine goaf fire
Show abstract
Spontaneous combustion in coal goaf area is one of major disasters in coal mines. Detection technology based on
signature Gas is the primary means of spontaneous combustion forecasting of coal goaf area. A real-time remote fire gas
detection system is proposed based on tunable diode laser absorption spectroscopy technology, to achieve valid test of
signature gas (CO, CO2, CH4, C2H2 and C2H4). The System uses the wavelength, respectively 1.567um, 1.608um,
1.653um, 1.530um, 1.623um near-infrared band fiber-coupled distributed feedback laser (DFB) as the light source,
Combined wavelength modulation spectroscopy and harmonic detection technique, developed a fiber-coupled white-type
long-path gas absorption cell, to achieve high sensitivity detection of gas concentration. The system achieved a remote
on-line monitoring of multi-component gas concentration,to meet the fire forecast need for Coal goaf area. There are
obvious advantages Compared with the existing beam tube monitoring system in coal mine.
Study on laser Raman spectrum with different excitation wavelength
Show abstract
The laser Raman spectroscopy can provide quick, simple, repeatable, quantitative non-destructive analysis and does not
require sample preparation and is applied in chemistry, physics, biology, medicine and other fields. The
short-wavelength laser (blue or ultraviolet) and the long-wavelength laser (red or infrared) can be used as the excitation
source. In this work, we find that some Raman peak of the molecular characterization will weaken or even disappear
when a longer or shorter wavelength laser used as the excitation source. We present the Raman spectra of benzene and
that of cyclohexane as an example, which are excited by different wavelength laser. The experimental results show that
the Raman peak corresponding to the vibration of CH(CH Raman mode) is much stronger than that of the C Ring(C Ring
Raman mode) when the excitation wavelength is 488 nm. When the wavelength increase to 785 nm, the CH Raman
mode almost disappears and the C Ring Raman mode increases sharply. This experimental phenomenon will be benefits
to the problem-solving of the analysis formula of Raman peak intensity. At the same time, it should be paid attention in
the Raman spectral analysis to the effect of excitation wavelength on it.
Digital speckle correlation method based on wavelet transform using micro-displacement measurement
Show abstract
As an un-damage measurement technique, the digital speckle correlation method (DSCM) has been used in many
measurement applications by advantage of its fast, sample and low requirement of the environment. However, its
calculation efficiency and the accuracy were poor. Here, a novel digital speckle correlation method based on wavelet
transform was proposed. Firstly, the dynamic speckle patterns generated by the sample were recorded, and then, the
multi-scale analyse of wavelet transform were using in DSCM. Furthermore, employing the optimum noise reduction
strategy, the dynamic speckle patterns were decomposed using symlets wavelet family, after that, the correlation
registers were conducted. In this study, the efficiency and accuracy of this method were thoroughly investigated by
theories and experiments. Compared to the traditional DSCM, the accuracy of this new method is improved dramatically
and the relative error is less than 1%. Furthermore, the calculated consuming time is decreased to half of the traditional
DSCM.
Velocity measurement by speckle modulating an Erbium-doped fiber ring laser
Show abstract
In this paper, Speckle modulating an erbium-doped fiber ring (EDFR) laser is used to detect the velocity of dynamic
diffused object. All-fiber structure of the speckle measurement system is set up. The autocorrelation function of speckle
signal related with the velocity variable of a moving object under test is theoretically derived. By experiments, the
speckle signals are acquired by a photodiode, and using the autocorrelation function, we calculated the correlation
coefficient of the speckle signals. When the coefficient is equal to 1/e, the velocity of the object is determined. In order
to explore the influence that the signal length affects on measurement accuracy, a group of signals with different length
of time is applied to calculate the velocity, and the result indicates that when signal length is greater than the correlation
length, the measurement error is very small.
Straight interference fringes thinning algorithm
Zhen Ren,
Zebin Fan,
Ping Ran,
et al.
Show abstract
The straight interference fringes are very common in the optical measurement such as Michelson interferometer,
interference of wedge, the diffraction of single slit, double slits, grating diffraction, the diffraction of thin straight line,
speckle correlation technique, moiré topography. etc. With the rapid development of CCD and computer technology, the
interference fringes are treated with efficient and fast image processing technique. Usually every interference fringe has
certain width and is of low contrast, and even there are gaps or holes in the fringes, the central position is difficult to be
located, therefore, the study of fringes thinning algorithm is an interesting subject. Many different algorithms have been
presented, every algorithm has its own shortcomings, such as complication of the algorithm, there are spurs or
discontinues on the final fringes, or unable to treat the low signal to noise ratio fringes. In this paper a robust and simple
algorithm has presented, which mainly including morphological image processing and unusually implement of 1×N
median filter to strengthen the horizontal fringes(supposing the fringes are in horizontal direction), to remove spurs and
to fill the gaps in the fringes. The experiment result confirmed the validation and robust of the algorithm. Even though
the image to be treated is of low signal to noise ratio and low contrast, smooth and continue straight fringes free of spurs
could be obtained.
Measurement of a turbid medium's refractive index with optical coherence tomography
Show abstract
A method of measuring a turbid medium's refractive index using optical coherence tomography (OCT) images is
presented. All of the necessary information for obtaining a sample's refractive index will be obtained through two OCT
images with and without the sample. The process of the measurement is simple and easy. The time of data gathering is
faster. Therefore, this method could provide a good way for measuring the refractive index of turbid media and materials
whose characters are easy to change. The refractive index of a sample, which has upper surface with arbitrary shape,
could be measured using the method. The data for measuring the sample's refractive index anywhere in 2-3 mm deeper
in the sample could be obtained at the same time. The method makes up the disadvantage of long time consuming and a
complex process in the focus tracking method. And it would make the optical path matching method developed further
more. The refractive indexes of some samples have been measured using this method and its validity has been proofed.
High-precision digital synchronous system in the physical diagnosis of multi-beam laser target system
Yingdong Xue,
Yonglin Bai
Show abstract
A high-precision synchronous system has been developed to control the diagnostic equipments in the multi-beam laser
target experiment. In the system, both digital delay and analog delay techniques are used simultaneously to realize the
high-precision time delay. By adopting the embedded intelligent chip FPGA, the resource consumption of the system is
obviously reduced; the performance of the digital delay part is improved. In the analog delay part, the capacitor charging
and discharging techniques are used to realize the delay resolution of 5 ps. To reduce the impact of the random trigger
signals, the jitter compensation circuit is also used in the design. The high-precision time delay and strong antiinterference
ability of the system are proved by the experimental results.
Design and research of analysis instrument based on Q-switch micro-crystal UV laser-induced fluorescence spectroscopy
Show abstract
The physical principle of micro- crystal UV Laser-Induced Fluorescence Spectroscopy (MUV-LIF) is expatiated in the
paper, and the application of MUV-LIF to organic matter is studied. Then a portable intelligent analysis instrument
based on MUV-LIF is designed. The instrument is composed of following units-----excitation source module based on
micro-crystal UV laser, laser driving and controlling module, sample cell, spectroscopy-detecting module,
processing and displaying module. Especially, because of high peak power and high repetition frequency rate, Qswitch
micro-crystal UV laser is selected as excitation source. MUV-laser module of the instrument is singlepolarization
solid-state coherent sources. The module is quasi monolithic integrated. The MUV-laser emits at
wavelengths of 355nm, 266nm and 213nm, and it has many advantages, such as high peak power (greater than
30kw), high repeat frequency rate (greater than 10kHz), subnanosecond pulse (less than 500ps pulse width). So the
excitation source module is an efficient compact high-order harmonic laser system. Laser driving and controlling
module supplies power regulator and temperature controller for MUV-laser. Fluorescence spectroscopy image is
produced by spectroscopy-detecting module and pre-processed in processing module. Qualitative and semi-quantitative
analysis of sample can be conducted by referring to fluorescence spectroscopy feature library. The experimental results
express that lots of organic matter, e.g. melamine, can be detected. The portal instrument has high SNR and sensitivity.
Mechanical characteristics of glass-ceramics surface by means of nano-indentation
Jinghe Wang,
Xun Wang,
Xiaoli Song,
et al.
Show abstract
Evaluating the surface mechanical characteristics of glass-ceramics by Nano-indentation method: contact stiffness(S),
strain hardening exponent (n) and the ratio of indentation area (c2), the changes of materials mechanical properties are
related to the degree of work hardening. The research results indicated that contact stiffness, strain hardening exponent
and the ratio of indentation area all change significantly when the indentation depth is 115nm. And coming to some
conclusions: through the relationship between contact stiffness and the indentation depth, knowing that when the
indentation depth is lower than 115nm ,the relationship is non-linear, and the glass-ceramic is not homogeneous; when
the indentation depth is lower than 115nm,the strain hardening exponent increases with the increase of the indentation
depth, when the indentation depth is higher than 115nm, the strain hardening exponent is stabilized to 0.30; when the
indentation depth is lower than 115nm, the ratio of indentation area decreases with the increase of the indentation depth
and when the indentation depth is higher than 115nm, c2 tends to stable. It can be seen that there is a depth of about
115nm affected layer on the ultra-smooth surface of glass-ceramic. The research of surface properties provides a
theoretical basis and related technology supporting for the gyroscope reflection substrate processing.
Measurement of beam waist of the long focal laser system
Hongying Fan,
Hao Zhang,
Qi Zhao,
et al.
Show abstract
A new application of Hartmann-Shack sensor is introduced to measure the beam waist from the information of measured
intensity and phase profile of wavefront. The result is achieved by Fresnel-Kirchhoff diffraction theory with proper
numerical approximate algorithm. In this paper, the algorithm is applying to the circumstance of long distance
propagation. For this specialty, a simulation process in the case of a Gaussian distributed beam and a thin lens of focal
length 100m is presented. And the results show the possibility of this method and the degree the result is affected
because of the inevitable error introduced in the measurement.
New phase measurement method for laser rangefinder
Show abstract
A new phase measurement method is designed and presented by using the technique of signal shifting phase and the
technique of signal multiplication for laser rangefinder. The intensity of laser light is modulated by cosine circuit signal,
at the same time the cosine circuit signal is thansformed sine signal by the shifting phase technique. Two signals
mentioned above are multiplied by received signal from the target respectively, then being transmitted into signal
processor after passing through low band filter respectively. The result of phase-shift between the received signal and
sent signal is calculated by means of signal processor and time-counter with double frequency of modulation signal. The
proposed system is composed of four units such as control and count unit, emitting and receiving unit of laser light,
signal processing unit and result display unit. The two most advantages of proposed system over others are its ability of
proper isolation which reduces crosstalk and its independency thermal drift. Theoretical calculations and experimental
results have shown the accuracy better than 2 mm.
Diffraction wavefront analysis of point diffraction interferometer for measurement of aspherical surface
Fen Gao,
Zhuang-de Jiang,
Bing Li
Show abstract
Point diffraction interferometer (PDI) is a new method for measurement of spherical or aspherical surface in extreme
ultraviolet lithography(EUVL) with hypo-nano accuracy. In PDI method, a nearly ideal spherical wavefront with
spherical wavefront error less than λ/105 rms, can be acquired through diffraction of a very small pinhole which diameter
is only a few microns. This diffraction spherical wavefront can replace conventional real standard lens, and be used as
reference spherical wavefront in PDI. The shape and quality of diffraction wavefront are key influence factors of
measurement range and accuracy, these must be considered strictly in designing.
In this paper, theory model of point diffraction is discussed based on theory of scalar diffraction theory. Relationships
between size of pinhole, range of diffraction and NA of measurable are obtained and diffraction wavefront error factors
such as pinhole size, roundness error are numerically analyzed. The analysis results show that a high accuracy diffraction
wavefront can be obtained through comprehensive optimizing of pinhole size, NA range, light intensity, shape error of
pinhole and so on. A pinhole with diameter no more than 2μm and radius errorΔr≤0.1r is suitable in designing and its
residual wavefront error can reach λ/105 in certain diffraction range. The analysis can provide reliable theory and
reference data for the actual design of point diffraction interferometer.
Effect of optical aberration of telescopes to the laser radar
Show abstract
This paper is focus on analyzing the telescopes used in atmosphere, which studies the effect of optical aberration of
telescopes to the laser radar. The method of numerical simulation is used to calculate and analyze the characters of
backward wave when laser beam propagates through atmosphere and reflects back. Then make use of optical transfer
function including quartic phase aberrations to get the beam quality denoting the laser beam pass through the telescopes
system with aberration. It takes advantage of angle-of-arrival fluctuations, radius of power in bucket, and scintillation to
study the effect of wavefront errors to laser radar. Furthermore, comparing the scintillation of backward wave by diverse
intensity of atmospheric turbulence, it discusses the effect of optical aberration to the accuracy of radar. By synthetically
numerical analyses, this paper concludes the quantificational effect of different aberration of telescopes to the signal of
radar. The conclusion of this paper can be used to direct the design and manufacture of telescopes of optical radar.
Study on the relationship between deflection angle and scanning angular of optical scanner
Show abstract
The optical scanner is a mature scanning device, which is mainly used in change light path, with high scanning speed,
with advantages of scanning angle and frequency fast adjustable and steady. Now widely used in laser scanning system
of the laser labeler and dual-beam spectrometer. When a certain angle beam incident scanner and the deflection angle
were constant, the reflecting beams produce a certain range of scanning angle. With the deflection angle of the scanner
changes, the scanning angle of the reflecting beam will change. The author make an intensive study of the relationship
between deflection angle and scanning angular founds that follows a definitive evolution and verified it. This conclusion
has very important instructional significance in the practical application and research of the optical scanner.
Test of film thickness based on annular sub-aperture stitching interference
Show abstract
The technology of annular sub-aperture stitching interference used in film thickness testing is an efficient route with the
characters of high-resolution and low-cost, which don't need compensation with auxiliary components. In this
contribution, the interference methods of film thickness testing and principles of annular sub-aperture stitching are
introduced, and then a model of annular sub-aperture stitching is established on the interference phase of thin film;
finally, Sub-aperture spatial phases are unwrapped by fast Fourier transform (FFT) algorithms, and based on this, annular
image is obtained by Zernike polynomial fitting algorithm and stitching objective function. The processing algorithms
program are written and simulated by a computer. A variety of affecting the accuracy of splicing factors of the errors are
analyzed in detail, and the solutions are given to reduce the errors, and proposed changes to the existing experimental
platform. The results show that the PV value and the RMS value of phase residuals of full aperture splicing are 0.0092λ
and 0.0036λ before and after stitching respectively, and it achieves a large aperture high-precision detection of film
thickness.
Alignment and arm length measurement of the swing arm profilometer using a laser tracker
Hongwei Jing,
Christopher King,
David Walker
Show abstract
In this paper, we present the use of the laser tracker to aid the alignment of a Swing Arm Profilometer (SAP)
and measure the length of the swinging arm, thus calibrating the operating radius of the SAP. The measurement
uncertainty analysis is given. A laser tracker is used to align the SAP to ensure the path of the probe head passes through
the rotary axis of the rotary table. By building the coordinate system by laser tracker measurement on the rotary table and
measuring the swinging arc of the arm, we can determine whether the swinging path of the probe head passes through the
rotary axis of the rotary table and perform the corresponding adjustment if necessary. A laser tracker is also used to
measure the arm length, i.e. the length between the probe's ball centre and the rotation axis of the swinging arm. By
placing a retroreflector or the tracker ball on the swinging arm and scanning the swinging path of the arm using the laser
tracker, we can acquire the data of an arc and fit to determine the length of the probe head center to rotation axis of
swinging arm, thus giving accurate SAP calibration data.
Point detection and positioning system of the target based on surface cluster eyes
Fang Guo,
Hao Zhang,
Keyi Wang
Show abstract
The research of target detection and position is a challenge task in the fields where machine vision was used to develop
various systems. However, monocular vision and binocular vision traditionally are difficult to meet the applications for
high resolution and high sensitivity. Because compound eye imaging system is capacity of the large field of view for
moving target detection with high sensitivity, the optical system has the potential to meet the applications above
mentioned. In this paper, a preliminary exploration of the surface imaging system for the characteristics of cluster eyes
was made and the optical signal processing methods of cluster eyes were introduced in detail. First the structure of the
cluster eyes was described and the imaging channels of cluster eyes were ray traced with Zemax. Then based on the
surface imaging mechanism with clusters eyes, the center of gravity of image space for target was extracted.
Subsequently by the neural networks training based on LM (Levenberg-Marquardt) algorithm, the non-linear relationship
between target and image was effectively calibrated. Finally, the corresponding relationship between target point and its
image point among the various channels was established. The experimental results show that the multicast visual
imaging systems are capable of providing the information of target azimuth and distance. Some attempts to study the
systems were made to achieve high resolution, high sensitivity of target detection and positioning tasks. At the same time
the surface imaging system also laid a solid foundation for the large compound eye imaging system from theory to
practical application.
Novel refractometer based on a phase-shift-adjustable fiber Bragg grating
Show abstract
A novel method to measure refractive index by using a phase-shift-adjustable fiber Bragg grating (PSA-FBG) is
proposed and demonstrated. The PSA-FBG was obtained by cutting a uniform FBG in the middle and introducing a
small air gap between the two FBG halves as phase shift. Tested materials were filled into the small gap so that the
quantity of the phase shift is related to refractive index of the tested material. Measurement of refractive index can be
carried out by measuring wavelength variation of the phase shift-induced narrow transmission window of the PSA-FBG.
Experimental results agree well with numerical analysis, showing a uniform refractive index sensitivity of 0.86 nm/u.r.i
with resolution of 0.012.
Research on the precision measurement of super-low reflectivity
Show abstract
Introduced a high-precision measurement of measured the super-low reflectivity and small sampling angle. Using
single reflect way measured, and compare with re-swatch. Testing the reflectance of the sampling mirror which be
used on TIL, and analyze the error. Research results indicate, the main factor which affect result is energy detector
error and energy detector linearity. This methods is easy and have high-precision, it can be used to measure the
super-low reflectivity sampling mirror reflectance.
Investigation on metal stress corrosion monitoring by laser speckle interferometry device
Jie Lu,
G. P. Zou
Show abstract
Stress corrosion is a synergy process between material stress and corrosive media. It is one of the most devastating
corrosion among all the corrosion behaviors. Often without any warning conditions occur, at high speed and resulting in
great loss of property and life. It is significant to study the stress corrosion. The aim of this work is to present a real-time
metal stress corrosion detection approach based on laser speckle interferometry. The specimens were Al-2A12 alloy with
thickness of 2mm which were immersed in the 3.5% sodium chloride solution. Three-point bending system was
employed under displacement loading mode. A series of speckle intensity images were captured by CCD sensor. In the
following corrosion analysis, an approach based on 2-frame, 4-frame and 8-frame image process algorithms named
inertia moment method was developed. The three-dimension results were obtained. Average intensity method was
recommended to contrast due to its validity for corrosion analysis. The detailed results show the different damage
tendency and potential failure region. The proposed corrosion monitoring devices and analysis algorithms has been
effectively proved to be employed in practical engineering with potential applications possible.
Analysis and discussion on the control system of human eye aberration measurement unit based on information fusion technology
Jian-heng Zhao,
An-cheng Xu,
Xue-tao Pan
Show abstract
The research reveals that there are higher-order aberrations in visual optical systems, and the important factors are
higher-order aberrations that affect the quality of vision to further improve. To correct the higher-order aberrations, the
aberrations of vision system must be effectively measured and analyzed. It is important to use the wave-front aberration
technology at the human ophthalmology disease diagnosis, especially in the field such as vision correction. Based on
that has been achieved, based on the Hartmann-Shack sensor a wave-front aberration measuring optical system
combining of the objective and subjective , the error of the wave-front aberration measurement data has been analyzed,
the required parameters in the human eye aberration correction were given, the expression based on information fusion
technology were gained. In this paper, the control system of wave-front aberration measurement unit has been in-depth
analysis and research. The measurement data acquisition system has been designed ,in the system, the information of
lighting optical path, the objective measurement optical path and subjective measurement optical path and other
information are fusion. A realistic program for control system design and peripheral interface circuit design has been
given.
Compound interferometer system for large-scale optical components surface measurement
Show abstract
Large-scale optical components is being applied more and more widely in the astronomical optics, space optics, groundbased
space target detection and identification, laser propagation in the atmosphere, inertial confinement fusion (ICF)
and other fields, especially the large-scale aspherical optical component is one of key parts which play a supportive role
in those fields. Large-scale optical components surface measurement instrument and technique has become a research
focus of many scholars in recent years. In this paper introduced a compound interferometer system, which based on the
principle of traditional Fizeau interferometer and lateral shear interferometer. In this system, produces two probe light
beams by a He-Ne laser, one of probe light beams is used to measure flat optical surface by using comparison with the
reference wavefront, and the other probe light beam is used to measure spherical and aspherical optical surface according
to the principle of lateral shear interferometer and without using reference wavefront. Discussed in detail optical layout
of the system as well as the principle of surface measurement, and the preliminary test results were given. The compound
interferometer system has a compact, multi-function, and good anti-vibration performance can be used for large-scale
optical plane (diameter less than 320mm), spherical and aspherical optical components surface measurement. Due to the
information that lateral shear interferogram carries does not show directly the deviation between the wavefront under test
and the ideal wavefront, but the wavefront difference, so the wavefront reconstruction method is more complex, and the
wavefront reconstruction algorithm from lateral shearing interferograms is also analyzed and discussed.
Measurement method of multi-degree-freedom based on laser collimation principle
Show abstract
A five-degree-of-freedom (including two displace errors and three angular errors) online measuring system is proposed.
Two mutually perpendicular prisms are fixed on a workbench of guideway and move along with the workbench. The
measuring system consists of two independent left path and right path with same light structure and principle. The
principle of displacement and angular measurement is analyzed, and optical structure is established. The system has
many advantages such as small and simple structure, high-precision and cheap cost.
Numerical simulation for effects of high-power laser propagation in atmosphere over land
Chun-ping Yang,
Yan Zhang,
Mei-lin Kang,
et al.
Show abstract
With the phase screen theory, distribution of light field on the take-over plane is analyzed and simulated after a
Gaussian laser beam propagates in the turbulent atmosphere. The square difference of light intensity scintillation is
given out, and compared with a static state statistical quantity theoretically. Analogously, thermal blooming effect is
introduced and simulated after a beam of high-power Gaussian laser spreads in atmosphere. A technique was
proposed that the empirical formula of thermal blooming was employed with a modification by turbulence effect.
The combined effects are introduced and simulated while a high-power laser beam propagates in atmosphere.
Evaluate the task-specific measurement uncertainty of laser tracker using Monte-Carlo method
Show abstract
In order to evaluate the task specific measurement uncertainty of laser tracker, based on the analysis of the uncertainties
of the laser tracker system(LTS) ,the Monte-Carlo(MC) method is proposed and applied, and it's principle and steps are
described. We have measured the flatness of the marble table with a laser tracker and a CMM, and compared with the
MC uncertainty simulation. The results of the MC method and laser tracker measurements are in well agreement with
each other, so we conclude that the MC methods could be used in the evaluation of the task-specific measurement
uncertainty of laser tracker.
Improved zone-plate interferometer for measuring aspheric surface
Liang Nie,
Gang Wang,
Guiqin Quan
Show abstract
The creation of referring wavefronts for the measuring aspheric surface is a challenge in the field of optical measurement
at present. The improved zone-plate interferometer is proposed to solve the problem in this paper. The principle of zone
plate interferometer is discussed and the theory modal is analyzed. The structure of the interferometer is designed and
slightly different from that of the Smartt zone plate interferometers. A new computer generated hologram (CGH) zoneplate
is designed and manufactured, which acts as null optical element in the interferometer. The corresponding
experimental system is built and the interferograms are processed with fast Fourier transform (FFT), phase unwrapping
and surface fitting algorithm. Theoretical analysis and experiment results indicate it achieves worthy measurement
precision.
Method based on video imaging to correct the consistency of multi-optical axes
Show abstract
The multi-sensor photoelectric systems, which collect laser ranging, laser-guided radiation, visible light imaging and
thermal imaging as a whole, are widely used at modern weaponry platform. The consistency detection of optical axis has
become a key to measure these systems' functions. According to the multi-optic-axis consistency detection's requirements,
this paper puts forward a new method based on video imaging to correct the consistency of multi-optical axes. This method
abandons the traditional methods based on the numerous refractions and reflections between many optical components. It
takes laser axis as the base and obtains the exposure point of laser beam in the scene through video imaging technology.
Then, by contrasting the exposure point and the TV's optical axis reticle, the TV's optical axis and the laser axis can be
adjusted and kept in consistency in the form of electric reticle. According to this method, a set of portable imaging detector
prototype that can be used to detect the consistency of multi-optical axes in the outfield has been made. This prototype can
achieve the consistency detection of CCD imaging system and thermal imaging system by adjusting them with the laser
range finder axis/laser irradiation axis separately. This prototype makes it simple and straightforward to adjust the optical
axes by the way of imaging. With easy operation, environmental adaptability and compact structure, this system is suitable
for the outfield testing and expected to be used for multi-optic-axis consistency detection online.
Quantitative detection of defect using ultrasound infrared lock-in thermography
Hui Liu,
Junyan Liu,
Yang Wang
Show abstract
Ultrasound infrared lock-in thermography (ULT), which uses ultrasonic wave to excite surface of a sample and lock-in
method to analyze thermal image sequence, and it is an active infrared thermography for non-destructive testing. This
technique can be used to detect crack, impacted damage in metal or ceramic material, and some typical defects of
composite, such as disbanding, delamination. Amplitude modulated ultrasound, which is injected into the sample and
converted into heat mainly in defects or areas with stress concentration. The generating heat travels to the surface by
conduction. Thermal image sequences which express surface temperature changing are obtained by an infrared camera
and processed by lock-in method to obtain phase image and amplitude image. Phase contrast and amplitude contrast
between defective area and sound one are used to indentify defects. In this paper, the theory and method of processing
thermal image sequence are researched based on the ULT. Experiments are carried out on a metal plane with surface's
micro-cracks for verification. It is obtained that the relations between geometric parameter of defect and the phase
contrast or the amplitude contrast at different inspecting parameters. A method of quantitative detection defects is
proposed by ULT.
Sidelobe reduction of acousto-optic tunable filter by double-filtering
Chunguang Zhang,
Hao Wang,
Yishen Qiu
Show abstract
For the high acoustic figure of merit of paratellurite (TeO2), it is the most widely used material for acousto-optic tunable
filters (AOTFs). The noncollinear AOTF has many applications such as spectral analysis and spectral imaging. We have
designed two noncollinear AOTFs which work in VIS range of 550 nm-680 nm. In these two AOTFs, the angle between
the propagating direction of the acoustic shear wave and [110] axis is designed to be equal. The two AOTFs are placed
fore-and-aft. As the two AOTFs are operated at the same time, a so-called "double-filtering" function takes place. By
analysis, it can be identified that the double-filtering method can be helpful to improve the performance of the AOTF. In
this letter, we have study the function of double-filtering on the sidelobe reduction. By computation, we have given the
results which can describe that the sidelobe has been decreased obviously in our studied optical wavelength range. Our
study indicates that double-filtering method can be used as a functional method for sidelobe reduction; it is significant
for the performance improving of modern AOTF.
Research on automatic Hartmann test of membrane mirror
Show abstract
Electrostatic membrane mirror is ultra-lightweight and easy to acquire a large diameter comparing with traditional
optical elements, so its development and usage is the trend of future large mirrors. In order to research the control
method of the static stretching membrane mirror, the surface configuration must be tested. However, membrane mirror's
shape is always changed by variable voltages on the electrodes, and the optical properties of membrane materials using
in our experiment are poor, so it is difficult to test membrane mirror by interferometer and null compensator method. To
solve this problem, an automatic optical test procedure for membrane mirror is designed based on Hartmann screen
method. The optical path includes point light source, CCD camera, splitter and diffuse transmittance screen. The spots'
positions on the diffuse transmittance screen are pictured by CCD camera connected with computer, and image
segmentation and centroid solving is auto processed. The CCD camera's lens distortion is measured, and fixing
coefficients are given to eliminate the spots' positions recording error caused by lens distortion. To process the low
sampling Hartmann test results, Zernike polynomial fitting method is applied to smooth the wave front. So low
frequency error of the membrane mirror can be measured then. Errors affecting the test accuracy are also analyzed in this
paper. The method proposed in this paper provides a reference for surface shape detection in membrane mirror research.
Considerations on testing of CFGT primary segments
Liyuan Jiang,
Xinnan Li
Show abstract
Larger primary collect more light. Limited by the casting techniques, the largest single primary mirror can be cast is
about 8.4-m. So segmented primary is widely adopted by large telescope with the aperture over 10-m since the twin
10-m KECK built or designed during the past two decades. Segmented primary creates new challenges for fabrication
and measurements. Chinese Future Giant Telescope (CFGT), a 30m telescope project, has been proposed by Chinese
astronomers. The primary of CFGT is a 30-meter diameter hyperboloid with a focal ratio F/1.2 and divided to 17 rings
evenly from the center to the edge. Each ring is divided into several sector-shaped segments with the size about
1.1-meter in diagonal. The total amount of the off-axis sector-shaped aspheric sub-mirror is 1122 including 17 different
types. In this case, how to test the large quantities of off-axis sector-shaped aspheric segments precisely and efficiently
with less cost is highly required to be considered. In this paper, the parameters of the CFGT primary and the 17 different
types of the segments are presented. Three potential methods of measurements for testing the large amount of CFGT
primary off-axis aspherical segments are compared and analyzed. The advantages and disadvantages of these three
measurements are discussed. By comparing, a method that test the segments with a standard flat mirror and another
method which tests the segments with a CGH and a test plate may be served as two candidates of the measurement for
CFGT primary segments. It may provide useful reference for the future research.
Method to detect and calculate motion blur kernel
Jiagu Wu,
Huajun Feng,
Zhihai Xu,
et al.
Show abstract
Motion during camera's exposure time causes image blur, we call it motion blur. According to the linear system theory,
if we can find the blur kernel which has the same meaning of point spread function, the blurred image can be restored by
the blur kernel using iterative algorithms, such as R-L (Richardson-Lucy). Performance of the restoration is deeply
depended on accuracy of the estimated blur kernel. In this paper we provide a novel method to detect and calculate the
blur kernel. The process of kernel estimation can divide into two steps: The first step is detection of the motion path
during the exposure time. A high-speed camera rigidly connected with the primary camera is used to capture a sequence
of low resolution images, which contain information of camera position. While displacements of those images are
detected, motion path can be drawn up. In the second step, blur kernel is calculated from the motion path by a novel
model provided by this paper. Finally the blurred image captured by the primary camera can be restored by the kernel.
We implement a hybrid imaging system for demonstration, and the experimental results prove the effectiveness of our
method.
Auto-measurement system of aerial camera lens' resolution based on orthogonal linear CCD
Yu-liang Zhao,
Yu-ye Zhang,
Hong-yi Ding
Show abstract
The resolution of aerial camera lens is one of the most important camera's performance indexes. The
measurement and calibration of resolution are important test items in in maintenance of camera. The
traditional method that is observing resolution panel of collimator rely on human's eyes using
microscope and doing some computing. The method is of low efficiency and susceptible to artificial
factors. The measurement results are unstable, too. An auto-measurement system of aerial camera lens'
resolution, which uses orthogonal linear CCD sensor as the detector to replace reading microscope, is
introduced. The system can measure automatically and show result real-timely. In order to measure the
smallest diameter of resolution panel which could be identified, two orthogonal linear CCD is laid on
the imaging plane of measured lens and four intersection points are formed on the orthogonal linear
CCD. A coordinate system is determined by origin point of the linear CCD. And a circle is
determined by four intersection points. In order to obtain the circle's radius, firstly, the image of
resolution panel is transformed to pulse width of electric signal which is send to computer through
amplifying circuit and threshold comparator and counter. Secondly, the smallest circle would be
extracted to do measurement. The circle extraction made using of wavelet transform which has
character of localization in the domain of time and frequency and has capability of multi-scale analysis.
Lastly, according to the solution formula of lens' resolution, we could obtain the resolution of
measured lens. The measuring precision on practical measurement is analyzed, and the result
indicated that the precision will be improved when using linear CCD instead of reading microscope.
Moreover, the improvement of system error is determined by the pixel's size of CCD. With the
technique of CCD developed, the pixel's size will smaller, the system error will be reduced greatly too.
So the auto-measuring system has high practical value and wide application prospect.
Defocus compensation system of long focal aerial camera based on auto-collimation
Yu-ye Zhang,
Yu-liang Zhao,
Zhao-lin Xu
Show abstract
Nowadays, novel aerial reconnaissance camera emphasizes on the shooting performance in high altitude or in long
distance of oblique photography. In order to obtain the larger scale pictures which are easier for image interpretation, we
need the camera has long focal length. But long focal length camera is easier to be influenced by environmental
condition and lead to great change of lens' back focus which can result in the lens' resolution decreased greatly. So, we
should do precise defocusing compensation to long focal aerial camera system. In order to realize defocusing
compensation, a defocusing compensation system based on autocollimation is designed. Firstly, the reason which can
lead to long focal camera's defocusing was discussed, then the factors such as changes of atmospheric pressure and
temperature and oblique photographic distance were pointed out, and mathematical equation which could compute
camera's defocusing amount was presented. Secondly, after camera's defocusing was analyzed, electro-optical
autocollimation of higher automation and intelligent was adopted in the system. Before shooting , focal surface was
located by electro-optical autocollimation focal detection mechanism, the data of airplane's height was imported through
electronic control system. Defocusing amount was corrected by computing defocusing amount and the signal was send to
focusing control motor. And an efficient improved mountain climb-searching algorithm was adopted for focal surface
locating in the correction process. When confirming the direction of curve, the improved algorithm considered both
twice focusing results and four points. If four points continue raised, the curve would be confirmed as rising direction.
On the other hand, if four points continue decreased, the curve would be confirmed as decrease direction. In this way, we
could avoid the local peak value appeared in two focusing steps. The defocusing compensation system consists of optical
component and precise control system and precise driver component. Based on FPGA hardware system, hardware
function is realized by VHDL. It has been using on some kinds of long focal CCD cameras and film cameras. It not only
has good dimensional stability and structural stability in harsh environment, but also has ability of focal surface precision
detection and accurate focusing.
Satellite APT system for Satellite-earth laser communication modeling, simulation and analysis
Ke Ding,
Yong-mei Huang,
Jia-guang Ma
Show abstract
The satellite-earth laser communication APT (acquisition, pointing and tracking) system's accuracy demand is described
and a method of modeling and simulation for error analysis is introduced at the beginning of this paper. Then simulation
architecture is given with the satellite APT system function description. Models such as atmosphere turbulence, satellite
platform vibration, motor & Gimbals etc are analyzed and established. Integrated simulations are done by assembling all
the models and controllers as a real terminal. How the factors such as sampling rate, system delay influence system
accuracy and how much the factors such as satellite platform vibration, atmosphere turbulence etc. contribute to the
system error are summarized clearly in tables. Some error analyses are done and a good choice of coarse and fine sensor
sampling rate is recommended combined with the system accuracy demand in the preliminary design.
Study on computer-aided alignment method of a three-mirror off-axis aspherical optical system
Xi-ting Zhao,
Wen-chun Jiao,
Zhi-bo Liao,
et al.
Show abstract
The precise alignment of multiple element off-axis optical system is a challenging task. In order to increase the
alignment process efficiency, computer-aided alignment methods utilizing Zernike polynomial coefficients have been
developed. In this paper, the misalignment state of three-mirror off-axis optical system is simulated in CODEV and
computer-aided alignment software. The corresponding relationship between the misalignment and Zernike polynomial
coefficients is analyzed, Finally, the alignment scheme is determined by the above analysis. In order to verify the
feasibility, by using inverse optimization method to join the different disorders analysis of come up with the ways of
solving the optimization variables, based on the established computer-aided alignment model to calculate misalignment.
The off-axis three-mirror telescope was aligned by measuring the wave-front error (WFE) in several fields, namely,
obtain Zernike polynomial, then using the self-compiled computer-aided alignment software to calculate the value and
direction of misalignment, this method is realized by optimizing adjustment to compensate for the other variables
misalignment-related variables. It can meet the precision requirement and accelerate the convergence of misalignment
variables. With variables deduced, the time of alignment is saved. At a wavelength of 632.8nm, the results of 0°field
wave-front error of 0.060λ rms, +3°field of 0.076λ rms and -3°field of 0.073; rms are obtained. The quality factor is
better than 0.85.
Application research on asynchronous vibration measurement of rotating blades based on optical-fiber sensor
Yugui Zhang,
Fajie Duan,
Tao Li,
et al.
Show abstract
Based on vibration measuring principle of blade tip-timing, fiber bundle sensor used as blade tip-timing is designed.
"5+2" scheme of double-rate sampling is adopt to solve the under-sampled problem of asynchronous blade vibration. By
using frequency identification, blade's real vibration information can be obtained. The method is applied on a model of
aerial equipment to do simulation experiment whose result is similar to theoretical model, and the frequency measured is
in accord with the result of strain gauge in general. Validity of measuring scheme is verified through the contrast result
which also declares high practicable value of this identifying technique.
Evaluation of anti-vibration capability of the wavefront testing method in time- and spatial-domain
Show abstract
The proposed wavefront testing method in time- and spatial-domain takes advantage of both active and passive phaseshifting.
It obtains stable wavefront with random noises removed after processing of large amount of serially collected
interforograms. Since the environmental vibration and air turbulence are adopted as the passive phase-shifting source,
this method performs well in normal laboratory environment without special vibration isolation or air flow control. This
method has application prospect in large-aperture optical surface test because it can help simplify the system and reduce
the cost and difficulty in fabrication. In order to quantitatively evaluate the anti-vibration capability of this method, the
influence of vibration on the measurement accuracy is simulated and analyzed. It is confirmed that corresponding to
certain accuracy tolerance, the product of maximum tolerant vibration amplitude and frequency is invariable. This very
product is adopted as the threshold indicating anti-vibration capability. More conclusions can be drawn after analysis
about the influence of active phase-shifting velocity, sampling frame frequency and relative sampling frame number on
the measurement accuracy: when the relative sampling frame number is fixed, the anti-vibration capability of the method
is increased with active phase-sifting velocity.
Study on spectrometer based upon volume holographic transmission grating
Zhen Huang,
Guodong Liu,
Zhong Ren,
et al.
Show abstract
In this present paper, a spectrometer based upon axial transmissive optical structure with the volume-phase holographic
(VPH) transmission grating technology is introduced. We give a physical insight for the structure and mechanism of
photorefractive volume holographic gratings and theoretically analyze some important performance parameters of the
spectrometer device using the coupled wave theory, which should be considered in the process of the following design
for the device with volume phase holographic transmission gratings. The experimental results show, owing to its axial
transmissive optical geometry and the perfect performance of the VPH transmission grating, the spectrometer based on
the volume-phase holographic transmission grating has satisfactory high resolution and wavelength accuracy. It has great
promise to be widely used in the future.
Study on attenuation performance of water fog to 10.6μm laser emission by laser granularity analyzer and transmitter
Xuanyu Wang,
Tianbao Fu,
Yuan Zhao
Show abstract
Superfine water fog was generated by several pressure nozzles with a diameter of 0.5mm in a large half-closed space
under different pressure varied from 0.1MPa to 0.9MPa. The granularity of the water fog particles was tested with a
spray laser particle size analyzer and the transmittance of the water fog to 10.6μm laser emission was tested with a
carbon dioxide laser transmitter. By the experimental result, the average diameter varies from 65μm to 5μm with the
pressure changes from 0.1MPa to 0.9MPa. On the other hand, the attenuation effect of water fog particles to 10.6μm
laser emission rapidly increases with the increment of its diameter when the particles have a smaller size, but the
attenuation effect slowly decreases with the increment of its diameter when the diameter is bigger than 15μm. The
scattering, absorption and extinction efficiency factors of water fog particles with different diameters to 10.6μm laser
emission were calculated according to Van Der Hulst formula. By the calculation, the attenuation effect of water fog
particles to 10.6μm laser emission depends on not absorption but scattering function. According to extinction curves, the
extinction efficiency factor of water fog particles to 10.6μm laser emission rapidly increases with the increment of its
diameter when the diameter is smaller than 15μm. The extinction efficiency factor will slowly decrease with the
increment of the diameter when the diameter is bigger than 15μm. Therefore, water fog has the strongest attenuation
effect to 10.6μm laser emission when its average diameter is about 15μm and the theoretic calculation is consistent with
the experimental result.
Disposition of camera parameters in vehicle navigation system
Houyun Yu,
Weigong Zhang
Show abstract
To resolve the calibration of onboard camera in the vehicle navigation system based on machine vision, a
respective method for disposing of intrinsic and extrinsic parameters of the camera is presented. In view of that the
intrinsic parameters are basically invariable during the car's moving, they can be firstly calibrated with a planar pattern
as soon as the camera is installed. The installation location of onboard camera can be real-time adjusted according to the
slope and vanishing point of lane lines in the picture. Then the quantity of such extrinsic parameters as direction angle,
incline angle and level translation are adjusted to zero. This respective disposing method for camera parameters is
applied to lane departure detection on the structural road, with which camera calibration is simplified and the measuring
error due to extrinsic parameters is decreased. The correctness and feasibility of the method is proved by theoretical
calculation and practical experiment.
Optical correlator based system for displacement auto detection
Chao-yue Dai,
Peng Ge,
Qi Li,
et al.
Show abstract
In airborne earth observation system, due to the movement of the flight and the vibration of the payload, the quality of
the picture captured will degrade severely because there exists a relative motion between the object and the imaging
system. With the development of high-performance, high-resolution CCD / CMOS technique and the further
optimization of imaging lens, the platform vibration becomes an important constraint in the high-resolution imaging, and
thus image stabilization for imaging systems is indispensable. The first step in image stabilization is to obtain the
vibration path by means of detecting the direction and length of the shake, and then to compensate for the shake using
some methods to eliminate the impact of vibration. In order to satisfy the need of fast displacement detection in the
image stabilization of airborne remote sensing system, we perform an auto displacement detection system based on joint
optical correlator in this paper. First we employ a vibration platform to simulate the scene with vibration in airborne
remote sensing system, and a high-speed camera system is set up to grab the target to form a video sequences with no
blur. Then two adjacent video frames will be input into a spatial light modulator parallelly in space, behind which a
Fourier lens is fixed to capture the spectrum of the object by a high speed camera. And after a high-pass filter, this
spectrum will be input into a spatial light modulator behind which fix another Fourier lens again, and another high speed
camera will capture the output image indicating the correlation peak position of the adjacent two images, from which
corresponding displacement vector can be calculated. Experiments show that this system works stably at a rate as high as
50 frames per second, with detection accuracy up to 0.1 pixel by centroid detection algorithm.
Determination the optical constants of hafnium oxide film by Spectroscopic ellipsometry with various dispersion models
Show abstract
Optical constants of vacuum-deposited hafnium oxide film (HfO2) from infrared to ultraviolet spectral region
(215nm-1700nm) have been determined by variable angle Spectroscopic ellipsometry with Cauchy dispersion model,
Sellmeier dispersion model, Cauchy-Urbach dispersion model and Tauc-Lorentz dispersion model, respectively. The
optical constants of the HfO2 film which were extracted with the four dispersion models have been compared. The
surface roughness layer between HfO2 film and air and the interface layer between the film and the substrate have also
been modeled with Bruggeman effective medium approximation (BEMA).
Research of fluorescence lifetime imaging technology based on heterodyne method of frequency domain
Show abstract
Principle of frequency -domain method to implement fluorescence lifetime imaging is introduced in the paper. Referred
to the excitation light, the fluorescence light has a phase shift and a reduced modulation degree. Both the phase and the
modulation can be used to determine the fluorescence lifetime. However, phase measurements are much more accurate
than measurements of the modulation degree. So the phase is used for lifetime measurements. Taking into consideration
the high frequency, the wide amplitude range of the fluorescence signal and the signal-to noise ratio, the better solution is
provided. As high frequency mixers do not work well for DC output signals, heterodyne principle is used. The
heterodyne method was used in the signal modulation technique so that the signal-to-noise ration is improved. The
advantage of the method is that the output signals of the mixers can be directly digitized so that effective digital filtering
algorithms may be applied and the phase can be determined via fast Fourier transform.
Establishment and study on dihedral angle detection model of retro-reflector based on Zygo interferometer
Xu Feng,
Wei Zhong,
Guo-hui Wu,
et al.
Show abstract
The dihedral angle of a retroreflector, which directly determines the quality of velocity aberration compensation, is
usually detected using a Zygo interferometer. However, since the software is effectively a black box, the user is unable to
determine the method and approach that is used to process the data. This also adds further difficulty of determining the
error inherent in the retroreflector. From the perspective of phase distribution, a mathematical model is built between
rectangular error and phase distribution. Combining the original data and area boundaries provided by Zygo
interferometer, and a numerical fitting method, the dihedral angle value of the retroreflector is computed, and then
compared with the value provided by the interferometer. Results show that the maximum difference between the two
values is 0.2". Considering that the measurement tolerance of the Zygo interferometer is 0.2", this suggests that the
computed value is consistent with the value given by the interferometer. Thus, computing method provides a new basis
and approach for dihedral angle detection for retroreflector manufacturers and users.
Optimal waveband and mathematical model for analysis of human whole blood glucose by near infrared transmission spectroscopy
Furong Huang,
Jianhui Yu,
Shiping Li,
et al.
Show abstract
The optimal waveband for quantitative analysis of the human whole blood glucose by near infrared transmission
spectroscopy is discussed in this paper. First, whole blood samples of different thickness (0.5mm, 1mm, 2mm, 4mm
) of the near-infrared transmittance spectra were analyzed respectively. It shows that the sample thickness of 0.5mm is
more suitable for spectral analysis. And then near infrared spectroscopy of 111 samples of 0.5mm thickness were
collected. Finally, different pretreatment methods of scattering correction methods, derivatives and different modeling
spectral regions were compared to find out their impact on mathematical prediction model. The result shows that the best
prediction accuracy was obtained in the waveband of 1500~1900nm by using Standard Normal Variate(SNV),the second
derivative spectra and Partial Least Square (PLS) regression. And the correlation coefficient(RP), the Root Mean Square
Error of Prediction(RMSEP) and the Relative Root Mean square Error of Prediction(RRMSEP) for the corresponding
model are 0.836, 0.271, 5.519%, respectively.
Improving the optimization efficiency and precision of least squares support vector regression (LSSVR) for pear property prediction
Yong Hao,
Yande Liu,
Hailiang Zhang,
et al.
Show abstract
In this study, Visible/near-infrared (Vis/NIR) diffuse reflectance spectroscopy at 530-1560 nm region was investigated
for the analysis of the soluble solids content (SSC) and color of pear. Least squares support vector regression (LSSVR)
has been proven to be a powerful tool for modeling complex samples through the use of adapted kernel functions.
However, one of the major drawbacks of LSSVR is that the optimization of the regularization and kernel
meta-parameters is time-consuming during training the model, and the modeling results are sensitive to spectral noise.
Wavelet compression pretreatment is an effective method for spectral information extraction and noise elimination. The
calibration set was composed of 75 pear samples and 32 pear samples were used as the validation set. The raw and
pretreated spectra by wavelet compression were modeled using LSSVR, It was shown that wavelet compression
procedure not only shortened the modeling time, but also improved the predictive precision. The correlation coefficient
(r) was improved from 0.78 to 0.93 for SSC, and from 0.95 to 0.96 for color, respectively. The root mean square error of
prediction (RMSEP), optimization time and calibration variables were reduced from 0.68, 0.33s and 1031 to 0.41, 0.03s
and 24 for SSC, while from 1.10, 0.33s and 1031 to 1.07, 0.03s and 40 for color. The results indicated that Vis/NIR
spectroscopy combined with wavelet compression procedure and LSSVR is a reliable approach for predicting the SSC
and color of pear.
Key technology of data registration for large aperture aspheric surface measurement
Tongqun Ren,
Yinbiao Guo,
Xiaolong Ke
Show abstract
Large measuring range and high resolution are always contradictories in practical measurement for large aperture
aspheric surface. They must be met simultaneously in high precision measurement. Stitching method based on data
registration is an effective way to resolve this contradiction. Aiming at the problem of rapid searching corresponding
points, a key problem in offset sampling point set registration under rectangular coordinate system, a complete and
effective approach is described in this paper. The original and destination point sets are registered roughly according to
initial transformation and then projected to x-y plane. The intersection of two planar point sets' minimal bounding
rectangle is solved to reduce the original points to be matched. The convex boundary of destination point set is solved
and then principle of connected graphs is employed to judge whether one original point lies in destination point set.
Strategy of space separating is employed to accelerate the neighboring points searching process. For each original point,
its neighboring points belonging to a small area are solved. Subsequently, quadratic surface fitting is performed based on
these neighboring points. Then method of Point-to-(Tangent) Plane is used to calculate its corresponding point. An
emulation experiment is performed and experimental results are presented to show the feasibility of the proposed
methods. It can realize rapid corresponding points searching effectively and meet the high precision registration under
the situation of offset sampling.
Method for measuring profile of large aspheric optics at grinding stage based on NC machine
Show abstract
According to the measurement at grinding stage, we put forward a method based on numerical control
machine tools(NC) to measure profile of large aspheric optic. First, we calibrate the straightness of the
machine tool sliding guide which is a critical component of the test system and has a function of
supporting and orienting, to improve the motion precision of that machine; and second, measure profile
of large aspheric optic with the help of NC machine and Heidenhai(MT60); and third, process the test
data to further enhance the precision of measurement.
Study on a novel algorism of phase unwrapping for interferogram processing
Jun-hong Su,
Wen-bo Wan,
Li-hong Yang,
et al.
Show abstract
Interferogram processing is one of main techniques in optical interferometry metrology. Modern interferometry for thinfilm
thickness has the advantages of noncontact, high accuracy and rich-field, etc. Taking advantage of Twyman-Green
interferometer, the relationship between interferogram and thin film thickness parameter can be determined by
mathematical model, thus the thickness of thin-film samples is measured automatically. A new algorism of phase
unwrapping for measuring the thin-film thickness is proposed based on the FFT method, this algorism identifies a seed
point, seed points spread to four points nearby the fist seed point, the four points will serve as the second group of seed
points, seed points spread to four points nearby the second group of seed points in turn, pass through all of the effective
information points by a diamond path. Seed points will eventually bring about the phase unwrapping in the entire image.
The results indicate that the height of the measured film sample, which is processed by the algorism processing software,
is 166.3nm. The height is 163nm by using the ZYGO interferometer to process the same sample. This method is superior
to the customary one. Although single interferogram was processed in this study, a phase distribution with high accuracy
was achieved.
Research on active suppression resonant peak of pneumatic vibration isolators at optical instrument platform
Jianzhong He,
Tao Liu
Show abstract
This article introduced the active control to suppress resonant peak at pneumatic isolation optical platform with
Multi-degree of freedom. In the field of optics, microbiology, precision weapon and solid material etc.
pneumatic isolation platform is the key basic equipment, which is supported with several pneumatic isolators to
cancel floor vibration disturbance and make the isolated precision optical instruments on it working stably.
Pneumatic isolation technique is passive isolation and exists in its system frequency characteristic resonance
phenomena in low frequency region, ranged from 1Hz to 6Hz, due to its limited physic parameters. Therefore,
pneumatic isolation technique is unsatisfied with the need of high stability optical instruments. The active
control to suppress resonant peak at pneumatic isolation has been developed in resent years, in which digital
active suppression controller is attached to the original pneumatic vibration isolation system and resonance
phenomena mentioned above is suppressed effectively. In essence the resonant peak suppression is system
damping problem with each degree of freedom. This article gives the mechanical drawing, mathematics' model
described in Lagrange's second equation and analysis of pneumatic isolation platform system, , and lists the
conditions of decoupling active suppression (or damping) and the form of velocity feedback on the basis of
math model analysis above mentioned. Further more the article puts forward a new algorithm of independent
active suppression (or damping) control with 3-degree of freedom for the pneumatic isolation optical platform
system, and presents its actual application and its frequency characteristic curves obtained by active
suppression and without. Last the article come to conclusions that
a. Compared with modals feedback suppression control, this new algorithm of active resonance
suppression (or damping) is easy to be realized and real-time
b. The active suppression with 3-degree of freedom above mentioned is not complete and it is
necessary active resonance suppression with 6-degree of freedom under some circumstances.
Design of a portable microfiber optic spectrometer
Jian-ping Tong,
Yang Yang,
Cheng-hua Sui,
et al.
Show abstract
Spectrum examination is widely used in scientific research and production. With the development of scientific research
and production, the trend of spectrum examination is from indoor to outdoor in situ examination and on-line monitor. So
the spectrometer is required to be more minimal. A new type of portable micro fiber spectrometer, using CCD, blaze
grating, and two spherical mirror, a small dispersing system based on crossing Czerny-Turner structure, is designed
based on this kind of requirement. By analyzing optical system structure, the relation among parameters of these
components has been found out in order to fix basic parameters for miniaturized spectrometer; its working wavelength is
200-910nm. The entire spectrum is detected by a CCD for one time, the selection of CCD is product of Toshiba
Corporation, linear charge coupled device (L.CCD) TCD1304AP, then received light signal is converted to an electrical
signal. The system's hardware circuit includes CPLD, MCU, the CCD driving timing circuit, signal conditioning circuits,
high-speed A/D sampling and transform timing circuit. A new kind of driving and sampling system which is high
integrated for multi-channel has been designed by using CPLD (complex programmable logical device) and MCU. In
this system, many function modules can be generated by logic cells inside of the CPLD chip, such as the driving pulse of
CCD, the driving timing of high-speed A/D sampling converter and storage system and so on. In the end, the A/D results
can be transmitted to computer by MCU for storage, processing and analysis. The CPLD is programmed in VHDL and
compiled, synthesized, simulated and burned with the helping of the environment of Quartus II. The design of portable
micro fiber spectrometer has the feature of wide spectrum range and high resolving power, so the system is especially
suitable in the application of portable filed examination.
Research on third-order susceptibility tensor of silicon at telecom wavelength
Show abstract
In this paper, the electro-induced birefringence based on Kerr effect and Franz-Keldysh effect in bulk silicon crystal at
1.3μm wavelengths has been measured. By using Kerr effect, the third-order susceptibility tensor of bulk crystalline
silicon has been calculated.The two independent tensor of silicon X (3) susceptibility can be obtained by
calculation (3) 6.22 (1 2.2%) 10 -20 m2 V2 and Xxyxy(3) = and xxxx(3) 9.13 (1 ±2.2%) 10-20 m2 V 2 = m2/V2. The research can drive the
silicon utility in the photo-electricity field.
Novel auto-focusing method
Yan Huang,
Dong Ye,
Rensheng Che
Show abstract
In this paper, an advanced auto-focusing method is proposed to improve the efficiency of the traditional auto-focusing
method based on criterion function with the same accuracy. Firstly, a depth from defocus auto-focusing method based on
autocorrelation of differential image is used to give a rough estimate of the right focus position with only two or three
defocused images. Then traditional method based on criterion function is used to find accurate focus position in this
rough field with fixed step-length mountain climbing servo (MCS). The experimental results demonstrate that this novel
method not only maintains the accuracy, but also has some advantages of rapid reaction and good performance for any
objects.
Calibration error of Hartmann wavefront sensor caused by nonuniform intensity distribution
Show abstract
The principle of Hartmann wavefront sensor is that the centroid angle deviation of spot equals to the mean slope of the
phase on the subaperture, but its precision is up to one of two assumptions: the beam is divided into plan wave and the
beam intensity distribution is uniform on each subaperture. When none of these two assumptions is satisfied in the
wavefront detection, the centroid angle deviation of far field spot is not exactly equals to the mean slope of the phase on
each subaperture, and finally the wavefront detecting error is produced. A similar case occurs when calibrating the
Hartmann wavefront sensor. The translation error of microlens arrays and the focal length differences of microlens arrays
would introduce defocuses on all subapertures, the centroid of the far-field spot is not the same as the mean slope of the
phase of calibrating beam when the calibrating beam has nonuniform intensity distribution, as a result, the calibration
error of Hartmann wavefront sensor comes out. Two formulas, which evaluate the calibration error associated with the
nonumiform intensity distribution and the defocus of microlens arrays are obtained in this paper, these formulas provide
theoretical supports to design and calibrate a Hartman Sensor required millesimal wavelength precision. Also a new
parameter is derived to characterize the nonuniformity of the intensity distribution.
Online detecting system of roller wear based on laser-linear array CCD technology
Show abstract
Roller is an important metallurgy tool in the rolling mill. And the surface of a roller affects the quantity of the rolling
product directly. After using a period of time, roller must be repaired or replaced. Examining the profile of a working
roller between the intervals of rolling is called online detecting for roller wear. The study of online detecting roller wear
is very important for selecting the grinding time in reason, reducing the exchanging times of rollers, improving the
quality of the product and realizing online grinding rollers. By applying the laser-linear array CCD detective technology,
a method for online non-touch detecting roller wear was brought forward. The principle, composition and the operation
process of the linear array CCD detecting system were expatiated. And an error compensation algorithm is exactly
calculated to offset the shift of the roller axis in this measurement system. So the stability and the accuracy were
improved remarkably. The experiment proves that the accuracy of the detecting system reaches to the demand of
practical production process. It can provide a new method of high speed and high accuracy online detecting for roller
wear.
FPGA and DSP based an intelligent visual sensor design for laser welding seam recognition
Show abstract
A kind of intelligent visual sensor system, which is mainly composed of a laser lighting source and an intelligent camera
based on FPGA and DSP, is designed using the triangle structured light principle for laser welding seam recognition.
Intending to meet the high-precision demands, on one hand, the components of the sensor such as the lighting source, the
optical lens, the optic sensor of the camera are selected and the errors caused by these parts are analyzed. Furthermore,
the triangle structured light principle models are built and the simulation is given to optimize the light path parameters.
On the other hand, the methods of the image processing for seam recognition using intelligent camera based on FPGA
and DSP are explained. Experiments results proved that the sensor design is reasonable and the image recognition
methods are rational and effective. Very compact structure, high-precision and high-real-time performance are integrated
in this sensor, so it can be applied well in the seam tracking and inspection system in the laser welding and arc welding
fields.
Research on ship wake detection mechanism based on optical backscattering effect
Show abstract
The characteristic of an incident light beam scattered from underwater bubble cluster was investigated and a Monte Carlo
model was employed to simulate the backscattered signal from bubbly wake by laser pulses. An optical ship wake
detecting experimental system was designed and built, in which there was a frequency doubling and Q-switched YAG
solid state laser adopted in the transmitter as the light source, and a telescope system with large limiting aperture and
small field-of-view(FOV) in the receiver. A photomultiplier tube was employed as the detector while simulated bubbly
ship as the detecting targets. The optimization of the system's parameters was studied in lab, the results showed that The
influence of laser pulse energy and the FOV size of receiving optical system on the detecting effect was studied by
experiments. The results showed that for near targets with small optical depth(ι ⪅1.4), the optimized Signal-to-Noise
Ratio(SNR) is obtained using a laser with single pulse energy of 60mJ~4;84mJ while for far targets with large optical
depth(ι⪆2.0), the optimized SNR is obtained using a laser with single pulse energy of 108mJ or above. Good detecting
effect is achieved using a receiving optical system with the FOV of 4°.
Research of laser ignition detection system
Feng Yang,
Dong Zhao,
Qie Xu,
et al.
Show abstract
Laser ignition is an important means of detonation but the accuracy and security is requested strictly. Based on the
above, two points were considered in the design: achieve ignition-Fiber-optical health monitoring in the condition of
low-intensity light (ensure the safety of gunpowder); observant the explosive imaging. In the paper, the laser ignition
equipment was designed with optical detection and inner optical imaging system for the real-time monitoring to the
optical fiber and the process of ignition. This design greatly improved the reliability and the safety of laser ignition
system and provided the guarantee for usage and industrialization.
Multiple disturbance location in distributed fiber-optic sensor based on phase generated carrier
Haiyan Xu,
Yi Zhang,
Hongyan Wu,
et al.
Show abstract
A novel distributed fiber-optic sensor based on Phase Generated Carrier (PGC) for determining the position of multiple
disturbances is presented. The configuration and operating principle of the system is illustrated, the location principle
and method for the detection system are analyzed. The system realizes the location of the multiple disturbances using the
PGC demodulation technology. Theory analysis and experiment result show that the proposed technology can realize the
detection and location of the multipoint disturb signals rapidly and effectively, this method is simply and can be obtained
easily, it could increase the length of fiber-optic sensors which has high measurement sensitivity and location precision.
Study on dynamic imaging on TDI CCD optical remote sensor of push-broom technology
Ming-hui Gao,
Lei Liu
Show abstract
A set special detecting system is proposed based on TDICCD push-broom technology applying in dynamic
imaging detecting experiment of space optics remote sensor. In the system, push-broom movement of the satellite is
simulated through using double supporting U structure precision rotary platform with remote sensor by angular
speed 0.555°/s,within the range of ±5° and control precision on steady speed achieves 0.3%; In the course of
detecting , regard Nyquist frequency target as detecting aim ,in order to solve matching uncertainty between the
CCD pixel and the vertical target strip image when the remote sensor does push-broom, make matching simplify,
enhance the measurement result the accuracy. So the tolerance a/n arithmetic progression gap target strip is joined in
each group of rectangular vertical group target strip. The remote sensor obtains in vertical, the level and 45° the
direction 0 fields of view, ±0.86 the field of view Nyquist frequency target strip image after detected, a group target
strip which can precision matching to TDICCD pixel at least can be obtained through analysis and dealing with
0.86 field of view's target strip image. The experiment not only verifies the detecting system's feasibility but
simultaneously verifies whether to have the high quality dynamic imaging quality when TDICCD push-broom
technology is adopted on the remote sensor developed.
Laser ranging based on secondary modulated beam
Dong Zhao,
Yang Feng,
Huang Tang
Show abstract
A novel CW-laser ranging method is proposed in this paper. This method gets the required range information not by
measuring the phase difference of the modulated CW-laser as in the traditional phase-shift laser ranging method, but by
comparing the mean light intensity of two linearly polarized components of the returned secondary modulation light. And
based on double refraction and total internal double reflection effect in crystal, a single block LiNbO3 crystal with
special shape is designed as the main device in this laser ranging method. Because of replacing the complex electric
devices by simply optic devices, this method not only simplifies the structure of devices, but also has a high precision.
The feasibility of the new idea is proved by a primary experiment, and a brand-new way for the laser ranging is provided.
Flexible coordinate measurement system based on robot for industries
Show abstract
The flexible coordinate measurement system based on robot which is applicable to multi-model vehicle
is designed to meet the needs of online measurement for current mainstream mixed body-in-white(BIW)
production line. The moderate precision, good flexibility and no blind angle are the benefits of this
measurement system. According to the measurement system, a monocular structured light vision sensor
has been designed, which can measure not only edges, but also planes, apertures and other features.
And a effective way to fast on-site calibration of the whole system using the laser tracker has also been
proposed, which achieves the unity of various coordinate systems in industrial fields. The experimental
results show satisfactory precision of ±0.30mm of this measurement system, which is sufficient for the
needs of online measurement for body-in-white(BIW) in the auto production line. The system achieves
real-time detection and monitoring of the whole process of the car body's manufacture, and provides a
complete data support in purpose of overcoming the manufacturing error immediately and accurately
and improving the manufacturing precision.
Novel design method for pulse laser reception circuit based on PIN
Tao Zhang,
Bin Wu,
Chang-jie Liu
Show abstract
Pulsed Laser Ranging is suitable for industrial security and surveillance applications for its high
measuring speed, large instantaneous power, long measuring distance, no cooperative targets and good
privacy. In this paper, the overall plan of industry security monitoring system which is based on Time
of Flight (TOF) pulse laser distance measuring equipment is introduced. Meanwhile, the part of pulse
laser receiving circuit was mainly studied. In order to improve the precision of the system, the pulse
laser needs a smaller pulse width. This means that the receiving circuit must have wider bandwidth and
higher gain for measuring longer distance. The structural characteristics of PIN are analyzed in this
article, and improvements on the design of trans-impedance amplifier are made according to the need
of the actual requirements. By the improvements, the trans-impedance amplifier shows higher
bandwidth than before at the gain of about 110dB. Results from experiment show that the rise edge of
the signal is made steeper by the change of the circuit, and that the precision of measurement results is
also increased.
Research on distributed fiber-optic sensor based motor fault monitoring system
Yi Zhang,
Haiyan Xu,
Qian Xiao,
et al.
Show abstract
A new running condition monitoring method of motors such as generator sets, and aircraft engines, using distributed
fiber-optic sensor was introduced in this paper. A Michelson Interferometer based fiber-optic sensor was constructed,
which offered a high sensitivity of disturbance detection. Because the sensing arm of the sensor was composed of optical
fiber, the distributed fiber-optic interferometric sensor provided a high capacity of anti-electromagnetic interference. The
monitoring system had a simple structure, and the sensor could be fixed on the motor easily to monitor its running
condition.
Study on the structure of CGH with same diffraction efficiency of 0-order and 1-order
Jian-feng Ren,
Peiji Guo,
Biao Zhang
Show abstract
In order to get an interference fringe with sharp contrast, the energy of reference beam and testing
beam approximate same in testing the off-axis convex aspheric surface using double CGHs. The fringe
contrast could reach 1 with same energy of these two lights.
According to diffractive theory, a novel structure of grating has been proposed to make 0-order
diffraction efficiency equal to +1-order diffraction efficiency by varying height of grating groove, duty
cycle and diffractive order. The efficiencies of 0-order and 1-order are both 28.8% when the duty cycle
is 0. 5 and the height of grating groove are 0.639π. In addition, this micro-structure can use the energy
of the induce-light effectively. This macro-structure pattern of CGHs may satisfy the requirement of
sharp contrast, which makes it possible to test off-axis convex aspheric surface with double CGHs.
Development of automatic dual-channel SPR detecting instrument
Qilin Li,
Shuyue Zhan,
Boshu Sun,
et al.
Show abstract
A self-developed automatic dual-channel detecting instrument based on SPR (surface plasmon resonance) principle was
presented in this paper. This instrument was constructed by the sample-load system, the sample flow-routing system,
SPR sensor and control circuit. Formed by a sample injection needle that can move up and down and a sample plate, the
sample-load system can realize the measurements of 15 kinds of samples, and the automatic cleaning of the sample
injection needle. The sample-routing system consisted of two precision syringe pumps and a microelectric valve, which
ensured that there is always solution flowing through the SPR sensor surface during the automatic sample injection
process. The whole sampling process was jointly accomplished by sample-load system, the sample-routing system and
the control circuit. Applying two section of air to isolate, it separated the sample from the buffer or the regenerated liquid,
and then reduced the instrument's measurement error. Sensor is the kernel of the whole instrument, and a self-designed
dual-channel SPR sensor was applied to this detecting instrument. The control circuit mainly included: the
MCU(microcontroller unit) control unit with the core of C8051F020 to control the automatic sampling system of pumps
and valves, USB2.0 interface circuit with the core of CY7C68013 to realize the dual-communication between PC and
MCU, the real-time data acquisition and uploading to the PC for further analysis and processing. The results of the
concentration detecting experiments and data analysis of sucrose showed that this system has good measurement
accuracy and stability.
A circular micro-grating array for Shack Hartmann wavefront sensors
Haiying Wang,
Ling Wei,
Jie Chen
Show abstract
A novel micro-grating array for Shack Hartmann wavefront sensors is presented. This circular micro-grating array shows
obvious advantage in matching circular aperture. It also provides a potential way of decreasing the expense of Shack
Hartmann wavefront sensors for its easy design and manufacturing procedure. An implementation is shown together with
experimental and measuring results. With this circular micro-grating array, a circular aperture can be matched by 100%,
which can avoid the lost of useful information when testing and measuring, at the same time, the regular focal spots array
will adapt to the common detectors which are always rectangular. In addition, another design and implementation of one
dimensional micro-grating array is also presented by which a higher efficiency will be available.
IR null correctors for ground aspheric surface
Yongqian Wu,
Yudong Zhang
Show abstract
This report gives the optical design and analysis of a two-element IR Offner-type null corrector for ground aspheric
surface. The optical system assumes an interferometer that consists of a point source, a 85 mm diameter relay lens, and a
20 mm diameter field lens. The aberration of the IR null correctors is PV0.0076λ.An optical test for measuring the null
correctors is presented in this paper.
Noise filtering for MoiréFringe signals based on variable step size adaptive neural network algorithm
Meng-jun Lv,
Qi Guo,
Chun-liang Zhang,
et al.
Show abstract
An adaptive filtering algorithm based on neural network is used to restrain noises of MoiréFringe signals. How to realize
this algorithm and its efficiency are studied followed. After analyzing the noises sources, the reason of adopting this
method is discussed. The realization of the algorithm and how to adjust the step size are made out. We subdivide the
signals filtered by way of tangent later. Based on comparing the characteristics of the original and the created signals, it
is showed that the subdivision precision is improved. When we subdivide circular grating MoiréFringe to 512 times by
using this algorithm, the maximum error is 1.236" in one individual pulse. The effect of this algorithm is better than
routine filtering methods because it has wide frequency range in improving the MoiréFringe signals quality and excellent
data preparation for subdivision.