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- Front Matter: Volume 6723
- Session 3-1
- Session 3-2
- Session 3-3
- Session 3-4
- Session 3-5
- Session 3-6
- Session 3-7
- Session 3-8
- Session 3-9
- Poster Session
- Additional Papers
Front Matter: Volume 6723
Front Matter: Volume 6723
Show abstract
This PDF file contains the front matter associated with SPIE
Proceedings Volume 6723, including the Title Page, Copyright
information, Table of Contents, Introduction, and the
Conference Committee listing.
Session 3-1
Method for 3D profilometry measurement based on contouring moire fringe
Show abstract
3D shape measurement is one of the most active branches of optical research recently. A method of 3D profilometry measurement by the combination of Moire projection method and phase-shifting technology based on SCM (Single Chip Microcomputer) control is presented in the paper. Automatic measurement of 3D surface profiles can be carried out by applying this method with high speed and high precision.
19-element sensorless adaptive optical system based on modified hill-climbing and genetic algorithms
Show abstract
A conventional adaptive optical system (AOS) often measures the wavefront slope or curvature straightly by a wavefront sensor. However, another alternative approach allows the design of an AOS without an independent wavefront sensor. This technique detect the image quality affected by phase aberration in laser wavefront rather than measuring the phase aberration itself, and then the image quality is taken as a sharpness metric. When wavefront phase aberration is corrected, the sharpness metric reaches its maximum value. In this paper, a wavefront sensorless adaptive optical system (AOS) has been set up. This system mainly consists of a 19-element piezoelectricity deformable mirror (DM), a high voltage amplifier, a set of 650nm laser, a CCD camera and an industrial computer. The CCD camera is used to measure the light intensity within an aperture of the focus plane, and then this intensity is regarded as the sharpness metric to optimize. A Modified Hill Climbing Algorithm (MHC) and a Genetic Algorithm (GA) are used to control the DM to correct the phase aberrations in this system. Experimental results show that both of these two algorithms can be used successfully in this indirect wavefront measurement AOS. However, the GA can obtain better performance than the MHC. After phase aberrations are corrected, the βfactor are reduced from 5.5 to 1.5 and 1.9, from 30 to 1.2 and 1.4 respectively.
Edge detection in optical images using auto-organization
Show abstract
Edge detection is one of the most demanding tasks in optical image processing for artificial vision and image matching works. In this paper, the self organization theory is used for edge detection. A new algorithm based on a two variable reaction-diffusion equations is proposed. A stable edge pattern can be obtained by choosing suitable control parameters. Compared with the conventional methods, such as Soble, Prewitt and Robert detectors, the new algorithm indicates a higher accuracy and continuity for the image. Moreover, it can also extract exactly the edge of the human face image.
Quantitative analysis of multi-component gas mixture based on AOTF-NIR spectroscopy
Huimin Hao,
Yong Zhang,
Junhua Liu
Show abstract
Near Infrared (NIR) spectroscopy analysis technology has attracted many eyes and has wide application in many domains in recent years because of its remarkable advantages. But the NIR spectrometer can only be used for liquid and solid analysis by now. In this paper, a new quantitative analysis method of gas mixture by using new generation NIR spectrometer is explored. To collect the NIR spectra of gas mixtures, a vacuumable gas cell was designed and assembled to Luminar 5030-731 Acousto-Optic Tunable Filter (AOTF)-NIR spectrometer. Standard gas samples of methane (CH4), ethane (C2H6) and propane (C3H8) are diluted with super pure nitrogen via precision volumetric gas flow controllers to obtain gas mixture samples of different concentrations dynamically. The gas mixtures were injected into the gas cell and the spectra of wavelength between 1100nm-2300nm were collected. The feature components extracted from gas mixture spectra by using Partial Least Squares (PLS) were used as the inputs of the Support Vector Regress Machine (SVR) to establish the quantitative analysis model. The effectiveness of the model is tested by the samples of predicting set. The prediction Root Mean Square Error (RMSE) of CH4, C2H6 and C3H8 is respectively 1.27%, 0.89%, and 1.20% when the concentrations of component gas are over 0.5%. It shows that the AOTF-NIR spectrometer with gas cell can be used for gas mixture analysis. PLS combining with SVR has a good performance in NIR spectroscopy analysis. This paper provides the bases for extending the application of NIR spectroscopy analysis to gas detection.
Research on acupuncture points and cortical functional activation position in cats by infrared imaging detection
Show abstract
The research of the brain cognition is mainly to find out the activation position in brain according to the stimulation at present in the world. The research regards the animals as the experimental objects and explores the stimulation response on the cerebral cortex of acupuncture. It provides a new method, which can detect the activation position on the creatural cerebral cortex directly by middle-far infrared imaging. According to the theory of local temperature situation, the difference of cortical temperature maybe associate with the excitement of cortical nerve cells, the metabolism of local tissue and the local hemal circulation. Direct naked detection of temperature variety on cerebral cortex is applied by middle and far infrared imaging technology. So the activation position is ascertained. The effect of stimulation response is superior to other indirect methods. After removing the skulls on the head, full of cerebral cortex of a cat are exposed. By observing the infrared images and measuring the temperatures of the visual cerebral cortex during the process of acupuncturing, the points are used to judge the activation position. The variety in the cortical functional sections is corresponding to the result of the acupuncture points in terms of infrared images and temperatures. According to experimental results, we know that the variety of a cortical functional section is corresponding to a special acupuncture point exactly.
Edge detection of grain image and algorithm of extra work
Show abstract
In order to get continuous and one-point-width of edge line, a method for noise-supprssion in accordance with rough
extent of image is presented. After getting the edge lineby way of wavelets transform, a suit of improvements for edge
line is established and adopted. Finally, a satisfied result is obtained with piece grain image segmented successfully.
Session 3-2
Research on real-time measurement and grading method for pearl color
Show abstract
The pearl color and color uniformity are important to its price. The paper presented a new real-time method to measure and grade the pearl color based on optoelectronic techniques. The method uses HSI (Hue, Saturation and Intensity) color model, diffuse reflection illumination, CCD (Charge Couple Device) camera with fine color reproduction and digital image processing technology to realize the parameters of color matrix of pearl color. These parameters, including mean values (h and s), variances (σh and σs) and absolute values of third moments (|th| and |ts|) of H and S, were acquired. Then the industrial control computer acquires the grading signals. The grading devices graded the pearls. The method could measure and grade the pearl on real-time and meet the requirement of grading.
Method of computer-aided precise alignment of unstable resonator
Show abstract
Automatic alignment of resonator is one of critical techniques in high-power laser technology. In this article, the method
of computer-aided alignment of unstable resonator is presented. The relation between mirror misalignments and phase
aberration coefficients of resonator is regarded as linear to some extent, especially under the condition of small
misalignments. By solving a system of linear equations the data of each misalignment can be acquired. Factors that
greatly influence the precision of calculation were also analyzed, and then some improvements are made in the
calculation. The whole process is simulated numerically based on a typical resonator configuration. The numerical
analysis shows that this method can be used to guide resonator's alignment effectively, and provide a new way of
automatic alignment of laser resonator in practical use.
Mid-frequency surface error test with a Foucault apparatus
Bin Xuan,
Junfeng Li,
Shumei Song,
et al.
Show abstract
Testing of mid-frequency surface error is of the first importance for fast optics, especially for large aperture aspherics. Foucault test plays a dominant role for surface error inspection before the digital interferometer age, but it seems to have faded out these days because no quantitative results turn out. However, an interferometer with high resolution CCDs is either unavailable or unaccessible in the process of manufacture. As its advantages are realized and recognized for the second time, Foucault test is going back to the stage again. A new theory of calculating the contrast of the shadow pattern of Foucault test is put forward in this paper and some modifications are discussed upon the analyses of the limitation of traditional Foucault apparatus. A paraboloidal mirror was fabricated and tested by the modified Foucault apparatus whose effect has been proved to be great. The methods of controlling mid-frequency error are described in the other paper at this conference- "Multi-mode combine manufacturing technology for large aperture aspheric mirrors"1.
Null compensation test with zero-power corrector
Show abstract
The null compensation-test method with zero power corrector for concave aspheric mirrors with deep relative aperture and wide clear aperture, including oblate ellipsoids which are very difficult to be tested, is investigated in detail. Based on the third-order aberration theory, both two-lens zero-power corrector and the three-lens zero-power corrector are introduced. This method is simple and free of chromatic aberrations. As for wide clear aperture and deep relative aperture concave aspheric mirrors, it is difficult to use a two-lens zero power corrector to do compensation test, so a three-lens zero-power corrector is used instead to solve the problem well. The design method of the corrector and specific design examples with clear apertures 800mm and relative apertures 1/2, 1/3, 1/4 of paraboloids are given and their design results are analyzed and compared.
Session 3-3
Ratio measurement of reactive ion beam etching rate using optical interferometry
Show abstract
The ratio measurement of reactive ion beam etching rate using optical interferometry was investigated. The principle is that the depth of groove could be showed by the bend of interference fringe. Using interferometric measurement, the depths of groove before and after etching were determined and marked as d1, d2. One new groove whose bottom was on the substrate was made. There are three photos before etching and after etching new grooves were got. It is found that the ratio is 10:3 under the conditions of experiment. Compared with traditional measurement, this kind of way has some advantages such as simplicity, higher measurement precision and so on.
Study on residual stresses of Ni-based WC coating by laser remelting based on XRD
Show abstract
The morphologies of Ni-based WC coating by flame spraying and laser cladding respectively were observed with
scanning electric microscope (SEM), respectively, and residual stresses were measured with XRD (X-ray diffraction). At
the same time, the spectra of WC coating were analyzed by XRD, and the forming mechanisms of residual stress were
analyzed. Experimental results are shown that residual stresses of Ni-based WC coating by flame spraying are all
tensile while those by laser cladding are compressive, chemical-physical reaction of the coating is the cause to result in
material volume change, which makes residual stress into compressive from tensile; when residual stress is changed into
compressive from tensile, micro-cracks on the coating surface greatly decrease, which is illustrated that the effect of
residual stress on micro-crack is obvious; XRD spectra peak of WC coating is only contained Ni and W, and has no
impurity and other reaction productions.
3D displacement measurement with a single camera based on digital image correlation technique
Show abstract
In this paper, a simple speckle technique utilizing a charge-coupled device (CCD) camera and frequency and spatial
domain combined correlation, is developed to measure 3D rigid-body displacement of an object. Rigid-body
displacement in an arbitrary direction in space consists of both in- and out-of-plane components. On the basis of the
pinhole perspective camera model, the presence of in-plane component of displacement results in a shift of the
displacement vector center and constant slope of the displacement vector is related to the out-of-plane component. The
proposed method facilitates the separation of in- and out-of-plane displacements. Based on the linear distribution features
of the displacement vector, digital image correlation (DIC) in global coordinates is employed to locate the displaced
position of each point on the object, which has been validated to be more accurate than conventional means. Correlation
in frequency domain is combined with the technique in spatial domain to improve the speed and automation in the initial
searching process. Simulation and experimental results demonstrate that both in-plane and out-of-plane displacements
can be accurately measured with the proposed method.
High accuracy measurements of objects with multiple reflective surfaces with wavelength shifting interferometry
Show abstract
A conventional phase shifting interferometer is capable of measuring opaque surfaces with sub-nanometer precision.
However, it cannot be used to measure an object with multiple parallel reflective surfaces such as a transparent plate, a
glass disk, or an Extreme Ultraviolet Lithography (EUVL) mask blank. This is because the plane parallel reflective
surfaces generate multiple interferograms that are superimposed in the recording plane of the interferometer. Although
every individual interferogram is associated with phase information that is related to the height or thickness, the
conventional interferometer is not able to differentiate one surface from another. To measure these surfaces, we have
developed a method that integrates a Fizeau interferometer with a tunable light source and a weighted least-square
technique. The tunable light source controls the wavelength during the data acquisition process, producing phase shift
speeds that are proportional to the optical path difference (OPD). The weighted least-square signal processing
technique separates each surface from the others in an optimal manner. Thus the desired information, such as the front
surface height, back surface height, and relative optical thickness of a plane-parallel transparent glass plate are extracted
without multi-surface fringe print-through artifacts. In this paper we will present the method and demonstrate its
performance. The demonstrated surface height accuracy for EUVL mask blank substrates is 5 nm and the RMS
repeatability is <0.01 nm.
Measurement of diameters of ultrafine particles based on characteristics of fluctuation of scattered light
Show abstract
The characteristic of fluctuation of scattered light from ultra fine particles carries information about diameters of
particles. This information is traditionally extracted by photon correlation spectroscopy (PCS). For this technique,
temporal autocorrelation function is utilized to analyze fluctuating scattered light of particles to get information of
particle size. Besides temporal autocorrelation function, both temporal coherence degree and fractal dimension of
scattered light from ultra fine particles can also be used to diagnose diameter of particles. From experiments, the fractal
dimensions of dynamic scattered light intensity signal of particles with the diameter of 60nm, 90nm, 200nm, 300nm and
450nm were obtained. Experimental results showed the monotony relationship between fractal dimension of scattered
light intensity signal of particles, which indicates that the fractal dimension of scattered light signal can also be used to
analyze particle size. However fractal dimension, as well as temporal coherence degree, can only provide the mean
particle size, not the particle size distribution.
Session 3-4
Measurement of lenses' power based on moire deflection technology
Show abstract
A method of measuring lenses' power using Moire Deflection Technology is described. Starting from the definition of
lenses' power and the principle of MDT, relationship between Moire fringes' tilting angle and the test lenses' power is
deduced. Calculated result shows that lenses' power is linear with the tangent of Moire fringes' tilting angle. The
corresponding calculating formula is given. Images of Moire fringes through a single lens, an aspheric lens and a
progressive addition lens are provided. Measuring results of single lens's power using MDT are presented, and the
relative measuring results using focimeter are given either. Meanwhile, comparison and analysis of the results are
discussed. It shows that measurement of lenses' power using MDT has high precision and it is simple and convenient to
implement. Furthermore, using MDT we can realize a whole measurement of lenses' surfaces, and this is very
meaningful to lenses with their power various on the whole surface such as progressive addition lenses. Therefore, it is
applicable and promising to test ophthalmic lenses using MDT.
Passive ring resonator gyroscope using high-order dispersion
Show abstract
A Passive Ring Resonator Gyroscope with high-order dispersion is proposed. In the system, the shift of frequency can be larger than conventional ones as the phase difference in the Ring Resonator is changed by high-order dispersion. It is shown that the sensitivity of gyroscopes with high-order dispersion may be several orders of magnitude higher than that of conventional gyroscopes. And equivalent dispersion which is controllable can be obtained by using a phase modulator inserted into a passive ring resonator.
Heterodyne interferometry for real-time displacement measurement by phase-to-amplitude conversion technique
Show abstract
The high precision measurement of displacement in nanoscale is crucial to nowadays many applications. We present a heterodyne interferoemtry with external modulation configuration for nanoscale displacement measurement. In the proposed method, the differential phase introduced by the displacement is converted into the amplitudes of quadrature heterodyne signals, so that the displacement can be determined from the amplitude ratio of the quadrature signals. The phase to amplitude conversion is achieved through the optical addition and subtraction by polarization tuning, which results in two phase quadrature signals in amplitude quadrature. Therefore, the proposed method also benefits from the feature of differential detection with common noise rejection. The nonlinearity of measurement due to polarization coupling is reduced by the conversion and the frequency coupling is eliminated by the external modulation approach. With proper phase bias to keep the interferometer in dark fringe operation, the shot-noise-limited performance is possible to realize. To demonstrate the capability of proposed method in real-time displacement measurement, we measure the dynamics of a commercially available PZT pusher and found close agreement between the experiment and the theory. The experimental evidence is also found with spectral distribution measurements, which demonstrates the minimum detectable phase and noise suppression capability of this approach.
High resolution detection system of capillary electrophoresis
Show abstract
The capillary electrophoresis (CE) with laser induced fluorescence detection (LIFD) system was founded according to confocal theory. The 3-D adjustment of the exciting and collecting optical paths was realized. The photomultiplier tube (PMT) is used and the signals are processed by a software designed by ourselves. Under computer control, high voltage is applied to appropriate reservoirs and to inject and separate DNA samples respectively. Two fluorescent dyes Thiazole Orange (TO) and SYBR Green I were contrasted. With both of the dyes, high signals-to-noise images were obtained with the CE-LIFD system. The single-bases can be distinguished from the electrophoretogram and high resolution of DNA sample separation was obtained.
Session 3-5
Imaging aberrations from null correctors
Show abstract
To test an aspheric surface, usually a null lens is designed to create an aspheric wavefront that matches the surface. The null lens also relays the image of the surface under test to the interferometer. The effect of image distortion from the null lens is well known, and is accommodated by remapping the data. Imaging aberrations created by the null lens also affect the measurement by smoothing out wavefront errors which correspond to ripples in the surface. This leads to data that does not faithfully represent the surface. We characterize this smoothing using a measurement transfer function, which is analogous to the modulation transfer function used to quantify the performance of imaging systems. In this paper we present a technique and tools for predicting the transfer function for a null test.
Analysis of infrared interferometry with laser noises
Xiangke Cao,
Rongzhu Zhang
Show abstract
Based on wave equation of light, with the technique of statistic analysis in signal and system field, an analysis model of semiconductor laser noise has been established. With this model the author analyzes the infrared interferometer used for optical surface test. The disturbance of phase noise acting on the interference field in the precise test process is discussed in detail. Numeric algorithm is employed to calculate the optical field distribution with phase noise propagating through an interferometer system.
High-resolution lensless Fourier transform holography for microstructure imaging
Show abstract
Digital holography combines the advantages of the optical holography and the computers. It can implement an all-digital processing and has the quasi real-time property. With lensless Fourier transform recording architecture, the limited bandwidth of CCD camera can be utilized sufficiently, and the sampling theorem is satisfied easily. Therefore, high-resolution can be achieved. So it is preferred in the microstructure imaging. In the paper, based on the Fresnel diffraction theory and the off-axis lensless Fourier transform recording architecture, the experimental optimization and correspondingly the digital reconstruction was investigated. Also, the lateral resolution of the reconstructed image was analyzed and improved by the proposed techniques. When the USAF test target was imaged without any pre-magnification, the lateral resolution of 3.1μm was achieved, which matched the theoretical prediction very well. The key points to achieve high resolution image are to use the smaller object and to arrange the distance between the object and the CCD plane as short as possible. Meanwhile, properly overlapping the reconstructed image with the DC term was helpful to improve the resolution. The noise in the reconstructed image could be reduced greatly by choosing the optical elements precisely and adjusting the beam path finely. The experimental results demonstrated that it is possible for the digital holographic microscopy to produce the high resolution image without the objective pre-magnification. The results also showed that, with a high quality hologram, the special image processing during the reconstruction may be unnecessary to obtain a high quality image.
Method for self-mixing interference signal analysis based on Kalman filter
Show abstract
In this paper, a new signal processing method based on Kalman filter is presented for self-mixing displacement sensor. Based on the approximate linearized model of a LD, the robust Kalman filter is designed for an estimation of system parameters and target displacement. The proposed signal processing algorithm increases the resolution well beyond half-wavelength, without any external optical components, preliminary separate measurements, or target surface preparation. Simulation analysis and experiments have been done to illustrate the validity and the effectiveness of the method. These results show that the displacement estimation is good with little noise and the estimated accuracy of about λ/20 is achievable.
Wavefront fitting and evaluation of fiber point diffraction interferometer
Show abstract
This paper presents Zernike polynomials fitting wave front which is detected by fiber point diffraction interferometer (FPDI). To confirm that Zernike polynomials are suitable for fitting concave spherical mirror surface, different orders of Zernike polynomials were used to fit several different surfaces which are produced by computer. Fitting result errors were evaluated by residual standard deviation. It is illuminated that Zernike polynomials are suitable for fitting surface which changes smoothly but not suitable for fitting surface with sharp fluctuating. When the shape changes dramatically Zernike polynomials are unable to correctly fit. Choosing appropriate term of polynomials, more terms don't mean higher precision. A metal coated concave spherical mirror, curvature radius 580mm, caliber 70mm, was measured as a sample. The five-step phase shifting interferograms of good quality were detected by an experimental FPDI which was built in lab. Measured wave front was fitted by 36 terms of Zernike polynomials from phase map which were unwrapped from five-step phase shifting interferograms. The measurement result was obtained and compared with that by Zygo interferometer when measured the same mirror. The 2 represented wave fronts have same characters such as centers bulging and marginal trough.
Session 3-6
Whole visible range imaging ellipsometry
Show abstract
The ellipsometric image contrast for patterned film in whole visible range is simulated and analyzed in this article. By the Fresnel equation and the Jones Matrix, the characteristic wavelength selection method to enhance the image contrast is built. The ellipsometric reflected intensity of specific thin film is nulled into dark by rotating the phase angle of compensator and the azimuth angle of polarizer in whole visible range, which results in higher contrast between non-null and null images after the proper wavelength selection. The approach enables the image defect recognition of patterned film more obvious than recent single wavelength imaging ellipsometry and white light reflective image.
Study on SD-LMS adaptive signal processing algorithm in space optical communication
Show abstract
In order to overcome the impacts on Space Optical Communication System brought by the turbulent in the atmosphere, the multi-transmitting technology, i.e. the space diversity technology is adopted in Space Optical Communication System to improve its properties at a lower cost such as reducing the error rate and raising its reliabilities. However, with the increase of correlations among the diversity signals, the validities of space diversity technologies decrease. On this condition, the adaptive diversity technology can be introduced to elevate the signal-to-noise rate. Under the condition of receiving correlative signals, with the help of combining selection diversity with adaptive signal processing technology, in this paper the SD-LMS (Selection Diversity-Least Mean Square) adaptive signal-processing algorithm is advanced. The following result could be obtained through the theoretical analysis: the signal-to-noise of outputting signals will be raised with the increase of the numbers of the diversity inputting signals, and the outputting signal distortion is similar to that of the single-way inputting signals. The simulating experiments show that SD-LMS adaptive signal-processing algorithm can significantly improve the properties of the outputting signals. The most prominent characteristics of the SD-LMS adaptive signal-processing algorithm is that it can automatically adjust the optimal weight factors of the adaptive filtering, and adapt itself to any changes of the noise without specially evaluating the properties of channels and noise.
Rapid detection of soluble content in beer using spectroscopic technique based on LS-SVM algorithm model
Show abstract
For rapid detection of soluble solid content (SSC) in beer, visible/near infrared (Vis/NIR) spectra of 360 beer samples were collected by using Vis/NIR spectroradiometer. Principal component analysis (PCA) was applied for reducing the dimensionality in order to decrease the overlapped information of raw spectral data, 6 principal components (PCs) were selected. The samples were randomly separated into calibration set and validation set, and least squares support vector machine (LS-SVM) algorithm was used to build calibration model of SSC in beer, then the model was employed for the prediction of the validation set. Correlation coefficient (r) of prediction and root mean square error prediction (RMSEP) were used as evaluation standards, and the results indicated that r and RMSEP for the prediction of SSC were 0.9829 and 0.1506. The precision of prediction was obviously higher than that of back-propagation artificial neural network (BP-ANN) and partial least squares (PLS) models, hence PCA and LS-SVM algorithm model with high prediction precision could be applied to the determination of SSC in beer.
Session 3-7
Light scattering characterization of self-affine fractal surfaces by a new algorithm of Levenberg-Marquardt method
Show abstract
Based on the correlation of scattered light intensity profile with self-affine fractal surface parameters of roughness w, the lateral correlation length ζ and roughness exponent α, we propose a new algorithm for the simultaneous extraction of three surface parameters from a single experimental scattered intensity profile data. With this algorithm, the fit of theoretical function to experimental data is used, and Levenberg-Marquardt method is introduced in finding the minimum of sum-squared error. In the iteration of fit process, the gradient and the curvature of sum-squared error function govern a jump of linear-descent to gradient-descent to guarantee the convergence and to accelerate the progress of parameters approaching their real values. In the experiment, we design precision system for the acquisition of scattered intensity data using the integration technique of Boxcar. All the actions in the experiment such as the stepped movement of surfaces, the sampling and the averaging of signals by Boxcar, the readout of the intensity data are also controlled by computer via an analog-to-digital converter. The results of the extracted surface parameters conform well with those by atomic force microscopy.
Method for measuring optical fiber core no-circularity
Show abstract
Tops of optical fiber are polished to be detectable, the tops come into plane, which are perpendicular to fiber axis. A
cirque pattern is formed on the out top of fiber by skew rays in the fiber. The pattern is shot with a digital camera. A
bitmap format cirque pattern is obtained. The inside and outside boundaries are taken out with digital image processing
method. Three different pels on the boundaries are picked out to define a circle at every space. The maximum and the
minimum diameter are picked out from many circles acquired to calculate the fiber core no-circularity in according to
definition. A quartz fiber core no-circularity was measured, with numerical aperture 0.22, and diameter 100 micron.
When the optical fiber was placed straight, periphery of the pattern on the out top appear regular denotation, the core no-circularity
is less than 4.0%. But the fiber is made into a spiral cord in diameter 20cm, the periphery of the pattern is
smooth, measured the no-circularity is about 1.7%, the result is identical to which obtained by microscope measurement.
The result indicates that no-circularity measured is almost independent of wavelength of laser with modes being
disturbed.
Measurement of out-of-plane displacement with a digital real-time holography
R. X. Guo,
Z. B. Fan,
H. Y. Qin,
et al.
Show abstract
A digital real-time holographic measurement system is designed based on the principles of double-exposed digital holography in this paper. In order to adapt this system to the variation of specimen size, a concave lens is placed in the classic 4f system, and then the object light path of this system, which transverse magnification can be adjusted by regulating the positions of lens, is equivalent to the 4f system. The object spectrum arriving at charge-coupled device camera (CCD) can be obtained by the Fourier transformation, and the complex amplitude of object wave can be obtained by the Fourier inversion. The phase variation corresponding to the initial object wave when the specimen is deformed can be gained by computer, and furthermore, phase variation corresponding to any of the two different displacement status can also be obtained. That is to say, with the help of this system, we can get much more information than that obtained by classic holography. The system has been used to measure the out-of-plane displacement of PMM specimen containing cracks. The holograms quality obtained by this system is close to that obtained by classic holography. The holograms obtained by digital real-time holography are also compared well with those obtained by classic holography. The digital real-time holography described in this paper can also be adapted for the variation of projection size of the specimen, therefore this system can be used to measure the specimens those projection size are larger than that of area-array of CCD.
Measurement of pH of rice wines using Vis/NIR spectroscopy and least squares-support vector machine
Show abstract
Visible and near infrared (Vis/NIR) transmission spectroscopy and a hybrid chemometrics method were applied to
determine the pH of rice wines. A spectroradiometer with a wavelength region of 325-1075 nm was used for spectral
scanning. The calibration set was composed of 240 samples and 60 samples were used in the validation set. The
smoothing way of Savitzky-Golay and standard normal variate (SNV) were used as data pre-processing methods.
Principal components analysis (PCA) was employed to extract the principal components (PCs) which were used as the
inputs of Least squares-support vector machine (LS-SVM) model. Then LS-SVM with radial basis function (RBF)
kernel function was applied to build the regression model with a comparison of partial least squares (PLS) regression.
The correlation coefficient (r), root mean square error of prediction (RMSEP) and bias of LS-SVM were 0.964, 2.62x10-4
and 8.83x10-4, respectively. Significant wavelengths for pH were proposed according to x-loading weights. The results
indicated that Vis/NIR spectroscopy with the combination of LS-SVM could be utilized as an alternative way for the
determination pH of rice wines.
Transition of luminance mode in dielectric barrier discharge
Show abstract
The transition among three discharge modes, glow-like discharge, filamentary discharge and diffuse discharge, has been obtained in air dielectric barrier discharge at 0.1atm pressure. To get the transition conditions, the electric waveforms and optical emission spectroscopy (OES) of the discharge have been measured. The results show that the wall charges and the ion concentration in the discharge are important to the transition of discharge modes.
Session 3-8
Method for eliminating the influence of light intensity modulation in sinusoidal phase modulating laser diode interferometer
Show abstract
In a conventional sinusoidal phase-modulating laser-diode (SPM-LD) interferometer, the wavelength of LD is sinusoidally modulated by varying its injection current. However, the intensity modulation is associated with wavelength modulation, which affects the measurement accuracy. We propose here a method to eliminate the effect of intensity modulation by choosing appropriate modulation depth for sinusoidal phase modulation in a SPM-LD interferometer. The method is verified by computer simulation and experiment for real-time displacement measurement. The measurement accuracy has been improved and the measurement repeatability is less than 1 nm.
New parallel plate interferometer for measuring angular displacement
Show abstract
A parallel plate interferometer with a reflecting mirror for measuring angular displacement is proposed. A deflection angle of a beam caused by an angular displacement is amplified by use of a reflecting mirror to increase the optical path difference (OPD) in a plane-parallel plate, which provides high sensitivity of phase measurement. Detection of light transmitted through the plane-parallel plate with a position sensitive detector (PSD) enables high accurate measurement of the initial angle of incidence to the plane-parallel plate with insensitivity to stray light. The improved parallel plate interferometer achieves a measurement repeatability of 10-8 rad.
Session 3-9
Phase transition characteristics of tungsten and tantalum doped VO2 polycrystalline thin films formed by ion beam enhanced deposition
Show abstract
V2O5 and WO3 or Ta2O5 mixed powders were pressed as sputtering target. The doped vanadium oxide thin films were deposited on SiO2 substrates by a modified Ion Beam Enhanced Deposition (IBED) method. The XRD results showed that IBED polycrystalline doped VO2 films had a single <002> orientation, and the crystal lattice constant d was elongated about 0.34% and 0.24% for W- and Ta-doped films relative to un-doped VO2 power. Temperature of phase transition from semiconductor phase to metal phase was 32°C and 48°C, and the phase hysteresis was 2.1°C and 1.2°C; the resistivity change magnitude was 1.6 and 1.2 and the temperature coefficient of resistance (TCR) of the doped films at 300K was 10.1%/K and 3.4%/K for V0.97W0.03O2 and V0.97Ta0.03O2 polycrystalline films respectively. The reasons would be synthetically in consideration of many factors, such as the differences of atomic size, valence number and bond length between W and Ta. The effect of W doping was more evident than the effect of Ta-doing.
Determination of subsurface damage in Nd-doped phosphate glasses
Show abstract
Nd-doped phosphate glasses have been widely used in high average power solid state lasers. Subsurface damage is one
of the most important sources to reduce laser damage threshold which limits the useful output of high-power lasers. To
eliminate subsurface damage (SSD), SSD detection must be done. In this paper, an instrument based on dimple method-a
destructive method was developed to detect and measure subsurface damage produced in each fabrication process.
Through the analysis of experimental data, we proved that there is a constant ratio between subsurface damage depth and
surface roughness PV value during loose abrasive grinding of glass. We also correlate subsurface damage and surface
roughness with the abrasive size. Experimental results show a good linearity. The ratio of subsurface damage depth and
surface roughness PV value during grinding Nd-doped phosphate glasses was found to be 3.94±0.22. The relation
between subsurface damage and abrasive size equals to 0.96±0.03. With this relation proved to be linear, subsurface
damage depth can be valued from the abrasive size without destructing the sample. We also find that the linear constant
of surface roughness and abrasive size is 0.25±0.02.With the constant, surface roughness can be estimated by abrasive
size directly. Furthermore, the spindle speed and load were taken into account. All the results are helpful to estimate SSD
and manufacturing high quality Nd-doped phosphate glasses. The way above can be applied for estimating SSD of other
brittle material too.
Application of adaptive optics in complicated and integrated spatial multisensor system and its measurement analysis
Show abstract
Adaptive Optics Expand System is a kind of new concept spatial equipment, which concerns system, cybernetics and informatics deeply, and is key way to improve advanced sensors ability. Traditional Zernike Phase Contrast Method is developed, and Accelerated High-level Phase Contrast Theory is established. Integration theory and mathematical simulation is achieved. Such Equipment, which is based on some crucial components, such as, core optical system, multi mode wavefront sensor and so on, is established for AOES advantageous configuration and global design. Studies on Complicated Spatial Multisensor System Integratation and measurement Analysis including error analysis are carried out.
Study on resolution of subdivision technique for grating based on CMOS microscopic imaging
Show abstract
The resolution of a new subdivision technique proposed in our previous studies, directly subdividing grating stripes by using the combination of CMOS microscopic imaging and image processing, was theoretically discussed and experimentally tested. The relations of resolution to the parameters, such as subdivision number, grating period, magnifying power, included angle, etc., were discussed in theory on the basis of resolution equations derived from subdivision principle and the object - image relation. And it was concluded that the resolution is higher as the subdivision number is more, the grating period is shorter, the magnifying power is higher or the tilt angle is smaller. Five subdivision systems with various resolutions were constructed with two kinds of metrological gratings and CMOS arrays and their performances were tested on an Abbe comparator with a minimum scale mark of 1 μm in the distance range of one grating period. The conclusion that subdivision system performs better under the higher resolution can be drawn from experimental results. At present, the maximum displacement error is 0.2 μm for the subdivision system with a resolution of 0.04 μm.
Poster Session
Numerical simulation of rough surface bidirectional reflectance distribution function (BRDF)
Weiwei Feng,
Qingnong Wei,
Shimei Wang,
et al.
Show abstract
Bidirectional Reflectance Distribution Function (BRDF ) has a wide use in surface detection and target recognition in the
surveillance system. There are many existing models used to validate experimental data and to represent the surface. In
order to make clearly the similarities and difference between the existing models, numerical simulation of several kind of
models were done, and the comparison and analysis between were made. To fit practicale application, a kind of new
model based on micro-facet theory was proposed. This model has both diffuse and specular components, which take into
account the geometrical effects such as masking and shadowing. The numerical simulation results are compared with the
experimental data obtained from a three-axis goniometer system on some typical materials. The comparison indicates
that this model fits well with experimental data and can satisfy practical use in a project.
Dynamic photoelectric autocollimator based on two-dimension position sensitive detector
Jiyou Zhang,
Tianquan Fan,
Xuedong Cao
Show abstract
In order to improve the measurement precision of an autocollimator and achieve dynamic measurement of small angle, a dynamic photoelectric autocollimator with high frequency response based on two-dimension position sensitive detector is designed by means of principle of autocollimation. The scheme and the design procedure of dynamic photoelectric autocollimator (DPA) are proposed. The dynamic accuracy measurement method of DPA has been mainly presented. A mirror was fixed on the uniform rotate stage. The DPA sample the angle of the mirror that was put on the rotate plat at an invariable sampling interval. The deviation between the angle of the rotate plat and the angle of mirror that sampled by DPA is dynamic accuracy of DPA. The experimental results indicate that the static accuracy of DPA is 1.0" with the measurement range of 400". The dynamic response frequency of the DPA is 5kHz and its dynamic accuracy is 1.9" with the range of 400". This method that measure two-dimension angular error is an effective approach to high-speed dynamic angular measurement.
Study on voltage biasing technique for spectral response measurement of multi-junction solar cell
Show abstract
Multi-junction solar cell (MJ) has been paid more attention for space and terrestrial concentrator system applications because of more efficiency has achieved. The spectral response (SR) of MJ is an important characteristic for technique optimization or performance evaluation. Measurement of SR of MJ cell is quite more difficult than that of single-junction solar cell (SJ) because a complicated light biasing and voltage biasing system is needed.
The object to be tested is GaInP/Ga(In)As/Ge triple-junction monolithic cells, and Ge bottom subcell with non-ideal properties would suffer from measurement error by improper voltage biasing. Since monolithic MJ cell without any middle taps, the internal characteristic is inaccessible, so the external biasing voltage usually obtained by estimating. It is well known that the characteristic of semi-conductor device has wide variance range, so significant deviation is often observed by a fixed estimating value. The paper proposes a method which could access the internal characteristic of MJ indirectly based on measuring other than estimating or mathematics model, and it has been proven by experiment with two SJ component cells, Ga(In)As cell and Ge cell.
Research on cruor measurement and its data processing method
Show abstract
With the development of modern medical research, people's understanding to thrombus and hemostasis is more and more profound. One of the remarkable characteristics is the rapid development of coagulometer and its widespread use for the examination of thrombus and hemostasis. After studying the present methods of cruor measurement, the paper introduces a cruor measurement method with double light beams based on Lambert-Beer Law. The point of the paper is the principle of cruor measurement and the method of data processing.
Instrument for testing the near and far field distribution of semiconductor laser
Xiaoguang Jiang,
Cun Zhuang,
Yingjie Zhao
Show abstract
To visually check out the semiconductor laser emitting, especially in judging Fabry-Perot (F-P) equivalent cavity faces near field luminescence condition and distant field giving out light condition, a test device is designed. By applying the simple component and principle, this device can realize the observation to glowing faculae of semiconductor laser, thus knowing the laser's properties such as optical density distribution, half power angle, angle of divergence, also discovering the concave wiring, the dark spot by observing the Fabry-Perot (F-P) equivalent cavity faces near field luminescence condition and distant field giving out light condition. It is a kind of good method for analyzing the situation of the active area cavity faces cauterization damage and internal structure flaws. So this device is suitable for teaching demonstration and direct observation of laser quality in manufacturing. It is also suitable for array laser chip testing, such as to see if chip gives out light, and to see the glowing intensity directly.
Optoelectronic noncontact measurement method for detecting the diameter of a bullet
Xun Zhou,
Hongtao Zhang,
Tianxiang Sun,
et al.
Show abstract
Based on laser-scan measuring principle, an optoelectronic non-contact inspecting system for detecting the diameter of bullet is presented. The measuring principle of the system is briefly introduced. The characteristics of the scanning speed are theoretically analyzed for the sake of the design of the system and improvement of the measuring accuracy of the system.
Optical and morphological characteristics of organic thin films for optoelectronic devices
Zhiyou Zhong,
Fenglou Sun
Show abstract
Organic semiconductor thin films of tri-(8-hydroxyquinoline)-aluminum (Alq), 9,10-di-(2-naphthyl)-anthracene (ADN), and N,N'bis(naphthalen-1-yl)-N,N'bis(phenyl)-benzidine (NPB) for optoelectronic devices were deposited onto glass substrates by vacuum sublimation technique. The surface morphology and roughness of the thin film were characterized by means of atomic force microscopy (AFM). Experimental results indicate that all thin films present similar granular topography but different surface roughness. In addition, the optical transmittance spectra of thin films were measured by a double beam spectrophotometer and their corresponding optical properties were investigated. The complex refractive index and the optical band gap of thin films were obtained, respectively. Meanwhile, the dispersion behavior of the refractive index was studied in terms of Wemple-DiDomenico single oscillator model, and the oscillator parameters were achieved.
Specular and diffuse reflectance of silicon photodiodes
Yingchun Zhou,
Tao Xu,
Huaping Chen
Show abstract
Now spectral reflectance of silicon photodiodes is described as the reflectance based on thin-film Fresnel formulas and the known refractive indices of the materials of photodiodes. In this paper the diffuse reflectance of light in Si materials is considered. A precision spectrometer is developed to measure the specular and diffuse reflectance of a silicon photodiode over the wavelength range from 400 to 900 nm. The results are compared with the corresponding values predicted by Fresnel model and diffuse model. It is found that the predicted values by Fresnel model show agreement with experimental values of specular reflectance. The diffuse model can predict both specular reflectance and diffuse reflectance well. This result can be used in auto-calibration technology for photodiode spectral response metrology.
Measurement of ultrasound field pressure with laser Doppler vibrometer
Tao Xu,
Ruixiang Lu,
Huaping Chen,
et al.
Show abstract
In this paper an optical method for measurement of the sound field pressure is presented. A laser homemade vibrometer
is used to measure change of optical path length caused by ultrasound field. With this method it is possible to obtain the
data of sound field pressure. The laser phase is recorded after it has passed through the sound filed. Through
mathematical derivation the laser phase of arbitrary slice of the sound field can be retrieved. The retrieved result is used
for digital image reconstruction of the ultrasound field. A 500μm diameter needle hydrophone is used to measure threedimensional
spatial distribution of ultrasound filed pressure with the propagation of time series and the result is
compared with that obtained from experiment with optical method. The related pressure amplitude show excellent
agreement with the results of comparison. It is shown that this optical measurement technique makes possible a very
accurate quantitative determination of ultrasound field pressure.
Fringe analysis with Hilbert transform and its application to the measurement of aspheric mirror
Show abstract
One of the important applications of aspheric mirror is the camera lens. Compared with spherical mirror, aspheric mirror has the advantage of improving the optics imaging quality, decreasing the optics weight, elevating its stability and reducing its cost. Although the process of aspheric mirror is becoming mature, the measurement of aspheric mirror still remains a problem.
The Hilbert Transform is very useful in the communications systems and the digital processing system. In this article, a method is proposed for interferometric phase's demodulation with a discrete Hilbert Transform. First, a Hilbert Transform demodulated phase principle is represented and the phase information of aspheric mirror is evaluated only from one interferogram. The sine and cosine components are calculated from a single interference signal, whose ratio of arc tangent is called interferometric phase demodulation. In addition, wave-front reconstruction is achieved by using Zernike polynomial fitting. Furthermore, the phase-extraction algorithm, error correction and some applications to the measurement of the surface shape are discussed so that on-line measurement of aspheric mirror is realized.
Angle deviation for coupling loss in fiber collimator packaging
Jianxin Qiu,
Feng He
Show abstract
The angle deviation in the packaging of fiber collimator is theoretically analyzed, and the resolution expression of the relationship between angle deviation of components and coupling loss of collimator is deduced due to transmission equation of GRIN (Gradient Index Lens).And it is pointed out that, angle deviation of optical components will cause off-axis coupling between two fiber collimators in a single fiber collimator assembly. For collimator coupling between collimators is more sensitive to angel matching, secondly to off-axis. So, in the assembly of the collimator, the angle deviation of optical components is one of the most important reasons causing coupling efficiency loss. If coupling efficiency loss of collimator is given, by this equation we could get the range of angle deviation, and then get assembly tolerance. Optimal tolerance of fiber collimator assembly put forward in the paper provides theoretic foundation to establish MOEMS of fiber collimator reasonable packaging technology and technique demands. It is practically beneficial for improving industrial production efficiency, the product characteristics and quality, and realizing the optic-machine-electrical integration assembly of fiber collimator.
Lock-in thermography for evaluation of destruction area and determination of depth
Zijun Wang,
Junyan Liu,
Jingmin Dai
Show abstract
Infrared Thermography is a Nondestructive Testing and Evaluating (NDT&E) technique that allows the non-contact inspection of systems and materials through a mapping of thermal patterns on the surface of the objects of interest. Defect detection principle in active thermography is based on the fact that a difference of thermal properties exists between the sound area and a defective region, which can be used for defect detection and quantification purposes. In this paper, experimental studies were made on the applicability to the detection of artificial defects in a steel flat plate with 12 flat-bottomed holes with three different sizes located at three different depths. The object was periodically heated by quartz lamps combined with light controller. The controller was operated by the same reference signal for the lock-in thermography. It was found that the defects were detected by localized contrast change in the phase delay images. It was also found that the location and size of defects can be estimated by the area of contrast change in the phase delay images which was clearly observed compared with conventional thermography techniques. The relationship between the values of phase delay and heating periods or modulation frequency was examined for several defect depths.
Research on lossless detection technology of aero-engine blade
Wangsheng Liu,
Xuhua Zhai,
Chijun Zhang
Show abstract
The paper presents an Airflow Detection Method to realize detections of aero-engine blades shape, and validates the development technology of engine blade shape, the design method of 3D blade optimizing, distributing rules of parameters for surface airflow and matching between airflow performance and models attaching surface shape, and research and analysis on numerical simulation method. The authors developed the design method of blade shape, and got an important achievement on theory of technology of blade shape design, High-powered blade shape modeling is the key technology of modern aero-engine development. By utilizing airflow detection method, one can perform lossless detection for aero-engine blade shape, offer effective method and key technology of research on high-powered gas compress.
Research and design of intelligent robot control system based on infrared and ultrasonic technology
Xin-Ling Wen
Show abstract
The intelligent robot control system is designed based on single chip microprocessor (SCM) of MC68HC908GP3, which is the core of the control system. Four groups of infrared/ultrasonic sensors, which constitute the monitor equipment to gather the information of each different direction, solve the problem of blind spot, and make up single sensor's shortage. The distance measurement sensitivity is improved rapidly and the monitor precision is less than ± 1% through using methods of pulse shooting, signal chooses circuit, and temperature compensation, etc.
Research on the application of multifunctional firearm test equipment in range testing technology
Chijun Zhang,
Hong Ma,
Xuhua Zhai
Show abstract
This paper studies on the application of multifunctional firearm test equipment in range testing technology. Its objevtive is to improve the level of firearm test technology in conventional range, to fill the gap of the test technology in our country. In this paper, it mainly discusses the principle and method of measurement on firearm size, sighting angle, locking force and loading force. Furthermore, it comprehensively analyzes test accuracy of sighting angle and the locking force. In addition, it finds out the problems in the current experimentation, which makes a good technical basis for improving the range test ability.
Research of space encoding and matching method in a stereo vision measurement system
Gang Chen,
Dong Ye,
Hua Chen,
et al.
Show abstract
In order to meet the progressively demand of measuring large size part in industrial applications, a precise and rather fast 3-D measuring system is developed by utilizing coded grid points. The LCD projection projects two groups of fringe sequences perpendicular to each other controlled by computer and form target points with the only code, these coded points as the target points on object surface. After matching process in the computer, the coded points' coordinates could be worked out according to stereo vision principle. In this paper, a kind of grid cross point's division, coding and matching method has been proposed, and at the same time, the centric of the coded points has been calculated. The above steps support the necessary condition for the coded points' coordinates calculation.
Study on laser damage properties of thin films
Show abstract
Thin film plays an important part of an optical system, especially high power laser system. The anti-damage ability is an important index in evaluating their quality. Both diamond-like carbon thin film and HfO2/SiO2 thin film are good optical thin films. In this paper their laser damage properties have been tested according to ISO11254. The results of damage threshold of coatings are shown as follows: Compared to HfO2/SiO2 thin film system with a laser damage threshold of 3.0~7.4 J /cm2, the DLC film threshold is only 0.6 J/cm2, which is the result of strong absorption of DLC films to laser energy. And also we can conclude from the results that the damage of film is derived from defect-induced damage, but the damage mechanisms are different. The DLC thin film damage results from heat-stress while HfO2/SiO2 thin films' damage results from plasma ablation. Besides, the substrate of film, the films' structure and deposition methods are also important to film damage threshold. Under the same condition, the threshold of the film on Si substrate is lower than those on K9 glass; with the same substrate, the film threshold is dependent of film thickness. As for deposition methods, films deposited by using ion-assisted method have higher threshold than those without using ion-assisted method.
Design of new-style integrated verification device for optical theodolites
Xiaosong Guo,
Zhi Zhu,
Haicheng Wu,
et al.
Show abstract
The configuration and function of the device have been described in detail. Using the device, we can verify all the main performance parameters of existing optical theodolites. We solve the problem of small-angle measurement by using one linear CCD. To overcome the inherent limitation imposed by CCD pixels to measurement precision, we proposed a subdivision method of interpolating edge pulse. By using this method, the ultimate error can be controlled within 0.5". We also proposed a novel "N" reticule. The reticule cooperates with linear CCD can easily accomplish two dimensional synchronous measurement of the angular deviation. For improving reading precision, we applied some image recognition techniques such as image enhancement, practical entropy threshold setting and sifting-continuity matching. The reading precision has been increased to 1". The measurement uncertainties have been evaluated at the end of the paper. The results show that the uncertainty indexes of the device can fully meet the requirements of verification work. The device has the advantages of small volume, high automation, convenient operation and good reading repeatability. It has been used in many measurement stations successfully.
Optical multichannel analyzer constructed with 4400 system for glass surface and thin film measurement
Show abstract
A new scheme of optical multichannel analyzer is developed based on Model 4400 Signal Detection and Analysis System. The scheme consists of an optical signal source, a photodiode array and Model 4400 Signal Detection and Analysis System. The signal source provides varies light intensity distribution from optical system. The photodiode array transforms spatial distribution of light intensity into time dependence of electric current intensity. Model 4400 Signal Detection and Analysis System carries out signal processing and analysis through boxcar, keyboard control and advanced microprocessor. With this scheme, the spatial distribution of laser light-intensity was described and the relevant parameters such as beam waist radius of Gaussian distribution were obtained. Further, the optical parameters of the plane glass surface and PMTES thin films were obtained by p-polarized reflectance method. By measuring the angle distribution of reflectance ratio and fitting the results with theoretical data, the optical parameters can be obtained easily. Experimental results indicate that the refractive index and extinction coefficient of glass surface layers decrease exponentially with the thickness of glass layer. Also the optical parameters of PMTES films with the presented scheme have been measured, and the experimental results coincide well with theoretical simulation only if the glass surface layers are considered. Due to the introduction of digital averaging technique in 4400 System, the sampling signals with higher signal-to-noise ratio are acquired, and the presented scheme has higher measurement precision, which is very suitable to temporal-spatial transform and analysis of optical field and precise measurement of surface and film system.
3D deformation measurement by digital speckle correlation method and stereo vision
Hua Chen,
Gang Chen,
Dong Ye,
et al.
Show abstract
An advanced 3D deformation measurement method based on 2D digital speckle correlation method and stereo vision is proposed in the paper. The intrinsic parameters and extrinsic parameters of two digital CCD cameras have been calibrated. The speckle images of the specimen from different directions are recorded by two cameras before and after deformation. The deformation displacement and strain of the specimen are calculated from these speckle images by digital speckle correlation method and geometrical relation of stereography. The whole field deformation can be obtained by tracking the gray character of each surface point in a subset. A new correlation search method based on genetic algorithm is proposed, which gets rid of great computational complexity and bad quality of conventional correlation search methods. The performance of the method is demonstrated by real test.
Correlation function of angle-of-arrival measurements with one-dimensional Shack-Hartmann wavefront sensor
Show abstract
Laboratory turbulence generator has been established by heaters and fans. Turbulence of different strength is able to be simulated by changing the temperature. Plane Shack-Hartmann wave-front sensor is used to measure turbulence. The measurement indicates that turbulence has properties of locally homogeneity and isotropy approximately. One-dimensional Shack-Hartmann wave-front sensor with high temporal sampling frequency and spatial resolution is designed, which is made up of 28×1 cylindrical microlens array and linear CCD with frame frequency from 100Hz to 3000Hz. Wave-front after propagating through the laboratory generated turbulence is measured by the wave-front sensor. From displacement of the intensity centroid, the components of angle-of-arrival fluctuation in different positions along linear CCD direction are acquired. One-dimensional correlation function of angle-of-arrival is estimated. Under the hypothesis of locally homogeneous and isotropic random field, it is convenient to derive one-dimensional correlation function of angle-of-arrival by method of spectrum analysis of random processes with stationary increment. The result of experiment indicates that one-dimensional correlation function of angle-of-arrival confirms to the theoretical derivation approximately.
Analysis for nonlinear error of improved 2D-PSD and its applications
Show abstract
Expound the lateral photoeffect, the operating principle, architecture and characters of improved two dimensional position sensitive detector. A new bridge theory is put forward to analyze the reason of nonlinearity errors produced by the center and edge of 2D-PSD. A signal processing circuit of improved 2D-PSD including high-precision, low temperature excursion and high input impedance preamplifier, summator, subtracter and divider is used in high-precision laser collimation system. The signal processing circuit converts the optical signals processed by optical system including optical lenses, diaphragm, light filter etc into electrical signals, then the electrical signals will be sent into data acquisition system. The straightness measure results of work-piece will be showed on computer by the linearity evaluation software. The characters of this system: fast response, high-resolution position, real-time detection etc. In the end, measuring results and some important conclusions are presented.
Study on living object identification based on genetic algorithms
Yao Wang,
Mu-di Xiong,
Si-nan Jia
Show abstract
Fast and effectual salvage can reduce accident loss, ensure people's lives and belongings safely when shipwreck occurs. It is very important that discovering objects should be timely and exactly to insure the salvage going on wheels. This text puts forward an object identification arithmetic based on Genetic Algorithms, which makes use of Genetic Algorithms to search living objects in the sea based on different infrared radiation characteristics between living objects and background, uses single point crossover method and simple mutation method with adaptive probability, ensures the global and local searching ability of Genetic Algorithms. Thus GA can accomplish searching course of optimization quickly and exactly with favorable searching ability. From identification test aiming at standard infrared image, it is seen that the image is strengthened by Genetic Algorithms, and the living objects can be identified exactly.
Study on initiative vibration absorbing technology of optics in strong disturbed environment
Si-nan Jia,
Mu-di Xiong,
Xiao-jie Zou
Show abstract
Strong disturbed environment is apt to cause irregular vibration, which seriously affects optical collimation. To improve the performance of laser beam, three-point dynamic vibration absorbing method is proposed, and laser beam initiative vibration absorbing system is designed. The maladjustment signal is detected by position sensitive device (PSD), three groups of PZT are driven to adjust optical element in real-time, so the performance of output-beam is improved. The coupling model of the system is presented. Multivariable adaptive closed-loop decoupling arithmetic is used to design three-input-three-output decoupling controller, so that high precision dynamic adjusting is realized. Experiments indicate that the system has good shock absorbing efficiency.
Research on 3-D device for infrared temperature detection
Shuxin Chen,
Shaohua Jiang,
Jie Hou,
et al.
Show abstract
In a certain field, it is important to measure temperature information in variable direction at the same time. However, there are few instruments to accomplish the function now. To implement the measure in 3 dimensions, an experimental table of temperature detection by infrared is designed. It is the integration of detection, control and monitor. The infrared device in the table can detect and measure temperature in real time, and the three dimension electric motional device can adjust the detection distance by the user. The mechanical bar for displacement is controlled by a circuit with the control button. The infrared temperature sensor is fixed on the bar, so it can move along with the bar controlled by the circuit. The method of temperature detection is untouched, so it can detect small object and its tiny variable temperature, which can not be detected by the thermometer or the electronic temperature sensor. In terms of the 3-D parallel motion control, the device can implement temperature measurement in variable directions. According to the results of the temperature values, the 3-D temperature distributed curve can be described. By using of the detection device, temperature of some special objects can be detected, such as the live anatomical animal, small sensor, nondestructive object, and so on.
Precision measurement for micro size based on support vector regression
Qiuwei He,
Longshan Wang,
Zhongdang Yu,
et al.
Show abstract
In order to improve measurement precision and measurement speed for micro size, a new kind of precision measurement method based on support vector regression for micro size parts was put forward. Taking the clip as the study object in this paper to measure micro distance of the clip slot clearance. First, the digital image of the clip was collected by A102FCCD device, and was input into computer by IEEE1394 digital card. Second, the original gray level image with noise was changed into edge information with single-pixel width after it was processed by reducing noise with median filtering, creating a binary image with threshold method and contour extraction, etc. Third, the detected regions were previously determined according to the proportions of clip length and width. Then pixel points on edges in the detected regions made up the training set of corresponding straight line, and the support vector machine for regression(SVR) was trained by the training set and regression function of every detected straight line was obtained, which is the expression of the sub-pixel, and then the clearance distance of clip slot was measured. Measurement precision acquired by support vector regression method is higher than measurement precision acquired by least square linear regression method through experiment contrast. Measurement precision can reach 1.05μm with support vector regression method. Finally, the measurement error was analyzed. Theory analysis and experimental results show that the method proposed is characterized by high speed and high precision.
Research of fabrication and testing technology of monocrystalline silicon optical elements with super-smooth surfaces
Show abstract
Fabrication and testing technologies of super-smooth X-ray optical elements of synchrotron radiation is a new field. It works in the short-waveband and is one of the basic contents of optical foundation engineering research of soft X-ray. This article describes optical system characteristics of synchrotron radiation light beam, research goal, significance, background, present situation of our country and comparison with overseas level in fabrication and testing technology of super-smooth synchrotron radiation optical elements. It presents domestic and foreign present situation of super-smooth optical surface fabrication technology, as well as each kind of measurement technologies of synchrotron radiation optical elements. This article relates on fabrication and testing of super-smooth optical elements made of monocrystalline silicon emphatically, systematically introduces fabrication, test method and result of the optical elements. All test results meet with the design specification. The paper also demonstrates the progress approached or achieved both at home and abroad.
Method for testing aspheric surface with wavelength scanning interferometry
Show abstract
In this paper, present test methods of optical aspherical surfaces are presented. The paper studies mainly a new kind of measurement method of aspherical surfaces-laser wavelength scanning interference test method. This research is aiming at putting forward a wavelength scanning interference test method. Processing and analyzing instantly-read interference patterns corresponding to continuous variable wavelength, the method overcomes the following disadvantages. For example, the longer reference arm, optical measurement environment in big-scale and high-accuracy aspheric testing and sensitive interferometer test system to disturbance, such as the oscillation of worktable, disturbance of air, and so on. Here, the authors describe the principle of elementary design of experiment device, and curtly introduce the method and principle for interference fringe processing. At the same time, this method and interferometric measurement instruments are studied and developed. We can not only perform surface test of high-precision aspheric surface, promote the application of aspheric, but also we can improve the integration of digital image processing, application of CCD and optical test.
Research on the measuring method of the slope error of EUV/x-ray optical elements and measuring apparatus of long trace profiler
Show abstract
The technology on the processing and detection of the extreme ultraviolet radiation and x-ray (EUV/x-ray) optical component is one of the main categories in modern short-wave band optical research. At present, EUV/x-ray optical component are in great demand on the construction of the rapidly developed synchrotron radiant lamp-house and beam of light engineering in developed countries. Now few countries has the ability of developing this kind of optical component with super-smooth surface and high precision and the key technology is processing and detecting technique. In this paper, the author study the measurement method and instrument of the EUV/x-ray optical component, improve the design of the measuring apparatus-long trace profiler LTP already existing, provide a kind of newly long trace profiler LTP-III, which is used to measure slope error.
Three-dimensional surface measurement system based on projected fringe model
Show abstract
A measurement system based on projected fringe model is presented. In this model, the location of fringe strips is determined by the image patterns on the projection plane directly, and the relationship between object point and its image point is established to obtain the coordinates of surface point. It is unnecessary to arrange the system in parallel, while the camera and projector can be in arbitrary position. Experiments show that the surface measurement system is applicable to many shape measurement tasks.
Research on magnetic intensity test based on light speed modulating with inner interfering
Show abstract
Under special environment, usually the magnetic intensity must be tested with full optical system. The purpose of the paper is to present theoretical analysis about testing magnetic parameter using light speed modulating and indicate the advantages to obtain new method of optical test. According to the light speed can be modulated in a photorefractive material in which written steady volume-index grating by two laser beams in opposite direction, so as to the light signal may transmit with phase modulating because of the intervening of another frequency shifting laser beam. In the experiment, the inner grating would be written in an optical fiber in which the suitable little Stannum has been doped. The periodic structure in the fiber can make the light signal reflect and the value of the phase shift is corresponding to the change of the periodic structure. With the quantum theory, the energy-band structure has a zero slope at the edges of the Brillouin zone and the group velocity of the photons at the band structure of a periodic structure is zero. According to the magneto-optical effect, the magnetic field may make the polarization plane change. After the two laser beams come into two ends of a fiber, the magnetic field can make their polarizations direction rotate and the interfering effect should be decreased simultaneously. During the testing period, a Sn-doped fiber is exposed to a magnetic field with linear distribution. Under this environment, the more increasing of magnetic intensity, the shorter length of effective steady grating in fiber is. Compared with light delayed signals transmitting through fiber in or not in the magnetic field, the delaying value may be correspondent to average magnetic intensity. This research work was supported by the National Natural Science Foundation of China under grant No.60472023.
Novel algorithm to improve sampling frequency of LSF
Show abstract
For having sample spectrum, slitting is often used as characteristic objects for OTF measurement. The common measurement methods of OTF from slit image data are firstly presented in this paper. According to deep analysis of image energy distribution of tiny tilted slit, Sub-Extremum Minimum Difference Method (SEMDM) is established. The method uses the rows with energy distributions of slit image stagger one pixel exactly to determine the scale of sub-pixel segment, and LSF data with 3 to 5 times sampling frequency are achieved by several-line low sampling frequency LSF data interpolation Practical test results prove that the algorithm is correct and reliable.
Research on strain-test based on light speed modulating method in FBG
Show abstract
Mostly, the principle of FGB strain sensor is to detect the shift of the central wavelength of FBGs. Now, we propose a new strain sensor using light speed extraordinary controlled method in a periodic structure modulated optical fiber. According to light speed which can be modulated in a photorefractive material in which written volume-index grating by two laser beams in opposite direction of fiber, the light signal may transmit with phase modulating due to intervening of another frequency shifting laser beam. In the experiment, the inner grating would be written in an optical fiber in which suitable little Stannum has been doped. Based on quantum theory, the energy-band structure has a zero slope at the edges of Brillouin zone and the group velocity of photons at the band structure of a periodic structure is zero. Due to the effect of stress, optical principal axle rotation angle of each beam is shifted, inducing the inner effective grating changed. During the testing period, pressure is put to a point of the fiber and fiber would be partly in uniform magnetic field. Under this environment, according to elasto-optical effect and magneto-optical effect, the pressing position and pressure value can be determined. This research work is supported by the National Natural Science Foundation of China under grant No.60472023.
Dynamic measurement of normal spectral emissivity (at 905nm) by a pulse-heating reflectometric technique
Peng Xiao,
Jingmin Dai,
Zijun Wang
Show abstract
Pulse-heating experiments were performed on the strip specimen, taking the specimen from room temperature to melting point based on rapid resistive self-heating of the specimen. The normal spectral emissivity of the specimen was measured by integrating sphere reflectometry developed at HIT. At the same time, the radiance temperature is measured by high-speed pyrometer from 1100K to melting point. Details of the measurement technique, measurement apparatus and the calibration technique are described. Results of normal spectral emissivity of niobium at 905nm from room temperature to its melting point are presented and discussed.
Temperature test of photorefractive materials using light speed slowdown method
Show abstract
In the paper, we propose one new type sensor with light modulation method. Having learned to delay a light signal by means of optical fibers, the temperature field may be detected by this way. According to the light speed which can be modulated in a photorefractive material in which written steady volume-index grating by two laser beams in opposite direction, the light signal may transmit with phase modulating due to intervening of another frequency shifting laser beam. In the experiment, the inner grating would be written in an optical fiber in which suitable Stannum has been doped. The periodic structure in the fiber can make the light signal reflect and the value of phase shift corresponds to the effective length of the periodic grating. According to magneto-optical Faraday effect, temperature may changes polarization direction by shifting Verdet constant. During testing period, a Sn-doped fiber is exposed to measured temperature environment and certain uniform steady field. Under this environment, the more the temperature increases, the shorter the effective interference area is in the fiber. Comparing with light delayed signal that transmits through fiber with different temperature, the delaying value may be corresponded to temperature. This research work is supported by the National Natural Science Foundation of China under grant No.60472023.
Large area of DLC films with end-hall ion source enhanced chemical vapour deposition
Show abstract
The end-hall ion source was used to deposit diamond-like carbon (DLC) films in a plasma enhanced chemical vapour deposition (PECVD) mode. The deposition system was characterized and optimized for infrared transmission enhancement applications and large area deposition onto silicon or germanium substrates. End-hall ion source and its ion beam current density distribution were discussed firstly. Secondly the diamond-like carbon (DLC) films were deposited by End-hall ion source in order to obtain large area DLC films. A great lot of technological experiments were done with various technological parameters, including anode voltage, distance from ion source to substrate for finding out the influence of technological parameters on film thickness uniformity. Thin film thickness was measured using ellipsometer in the wavelength from 400 to 1600nm. Finally, the influences of technological parameters on film uniformity were achieved, large area DLC films were obtained, with diameter 200mm, relative thickness error less than 5%. The DLC deposited on a single side of double-sided polished silicon wafers resulted in a transmission of 69.5% in the wavelength of about 4 μm closes to an ideal value.
Development of a new type of optical microscope
Show abstract
Along with the development and application of nanometer technology, a machine that allows deterministic position and manufacturing at the atomic level is required. An optical microscope of the machine was designed particularly to locate line features on a grid plate. It was designed to achieve nanometer level repeatability. The microscope uses a modulated light-emitting diode as its light source. It has two channels for optical imaging: one consists of two slits for precision measurement of line positions and the other of a camera for direct visual observation. A lock-in amplifier is used for demodulating the electrical signal from the photodiodes behind the slits. Initial experiments locating crosses on a grid plate indicate a repeatability of approximately 1 nm, one standard deviation. It was found that the measured line position is related not only to the focus but also to the illumination. There exists a particular orientation of the illumination where the measured line position is relatively insensitive to the focus, because of which the microscope is able to achieve nanometer level repeatability. Repeated measurements were performed on both an uncalibrated and a calibrated plate. Repeatabilities of better than 1 nm were obtained over time periods of several days; however, the ultimate accuracy of the machine still has to be demonstrated.
Research and application of video test system based on FPGA
Xiancheng Zhang,
Yuekang Shan,
Li'na Yang
Show abstract
In this paper, a new automatic test method based on Field Programmable Gate Array (FPGA) is presented. The video information of workpiece is obtained by using the CCD camera, process this information and generate the row synchronization signal and the scene synchronization signal by the synchronous separate circuit, at the same time, generate the binary information of the video signal by the binary decision circuit, then the video graduation module which is realized by the FPGA is used to analyze and process this signal and Figure out the test result. The video graduation technology based on FPGA is researched in this paper, the generation principle of the video vertical line and video horizontal line are introduced in detail, the test principle of video line is explained, the hardware and software design of the test system are given, and the test error of the system is analyzed. This method needs simple circuit, convenient operation, and has high reliability, the system's function is extensible, in addition, it tests rapidly, low-cost and has high precision. The system, which has been implemented in automatic test for the mesh status between wormgear and worm of the induction ammeter, has been tested a lot, and is shown to be able to test the ammeter effectively. Also, this system fits to mass-produced workpieces' dimension test on the product line, and helps to improve produce efficiency and enhances product quality.
BP neural network application on surface temperature measurement system based on colorimetry
Show abstract
Measurement of the features of infrared radiation is very important for the precaution and discrimination of missiles, and relevant research is worthy in military application. The measurement of target's surface temperature is the foundation of infrared radiation characteristics measurement. The principle and configuration of target's surface temperature measurement system based on colorimetry is introduced, the measurement model is deduced and the processes of temperature measurement are presented. Least-square method and back-propagation neural network method are both used to deal with the demarcating data. Compared with the least-square method, Back-propagation neural network has more advantages, such as high precision, good applicability and so on.
Research on coal-mine gas monitoring system controlled by annealing simulating algorithm
Show abstract
This paper introduces the principle and schematic diagram of gas monitoring system by means of infrared method. Annealing simulating algorithm is adopted to find the whole optimum solution and the Metroplis criterion is used to make iterative algorithm combination optimization by control parameter decreasing aiming at solving large-scale combination optimization problem. Experiment result obtained by the performing scheme of realizing algorithm training and flow of realizing algorithm training indicates that annealing simulating algorithm applied to identify gas is better than traditional linear local search method. It makes the algorithm iterate to the optimum value rapidly so that the quality of the solution is improved efficiently. The CPU time is shortened and the identifying rate of gas is increased. For the mines with much-gas gushing fatalness the regional danger and disaster advanced forecast can be realized. The reliability of coal-mine safety is improved.
Study on load temperature control system of ground laser communication
Xunhua Zhai,
Hongtao Zhang,
Wangsheng Liu,
et al.
Show abstract
The ground laser communication terminal as the termination of a communication system, works at the temperature which varies from -40°C to 50°C. We design a temperature control system to keep optical and electronic components working properly in the load. The load is divided into two sections to control temperature respectively. Because the space is limited, we use heater film and thermoelectric cooler to clearify and refrigerate the load. We design a hardware and a software for the temperature control system, establish mathematic model, and emulate it with Matlab.
Applied research on four-quadrant optoelectronic detector for surface topography measurement
Shuzhen Wang,
Suping Chang,
Tiebang Xie,
et al.
Show abstract
A spatial arrangement of four-quadrant optoelectronic detector is presented to detect interference fringes in 3D surface topography measurement. By putting the '⊞-shaped symmetry four-quadrant optoelectronic detector into the interference fringes region inclined at a certain angle, the difference signal with a higher SNR can be obtained even the shape or width of fringes may vary in a certain range. The relationship between interference fringe width d, photodiode arrays rotary angle β, and amplitude, phase difference of the difference signal is analyzed by integral analysis in ideal conditions. Appropriate value of fringe width d and associated rotary angle β that meets orthogonality relation are given. The results of the experiment and analysis indicate that the two difference signals satisfy the requirement of counter and subdivision and thus can reach the accuracy of nanometric scale measurement by the spatial arrangement of the photodiodes.
Analysis for maladjustment properties of passive confocal unstable resonator by using Hartmann-Shack wavefront sensor
Show abstract
The effect of intracavity aberration perturbation on output mode structure properties of passive confocal unstable resonator is been experimentally researched by adopting Hartmann-Shack method on the basis of numerical simulation. The results show that intracavity tilt aberration affects the outcoupled intensity distribution, but only a small intracavity tilt perturbation will not obviously augment the high-order aberrations of beam phase properties. The tilt aberration, coma aberration and astigmatism will all be brought, and also tilt aberration is the main component when intracavity mirrors have a vertical movement along the direction of optic axis. When adaptive optical elements such as deformable mirrors are adopted for intracavity aberration correction, the correction for tilt aberration should be considered at first.
Research on fiber grating sensing to fiber loop ringdown
Show abstract
A fiber loop consists of two couplers and a single mode fiber and the measured pressure is converted into ringdown time of light traveling in the fiber loop by the sensor element of FBG. When pressure is changed, the pressure will be directly proportional to the ringdown time which is identical to that of theory. This kind of system of measuring press based on the theory has advantages of simple composition and convenient measure and it provides a novel method of fiber gratting demodulation technology and has practical value. Apart from measuring press, it can measure temperature and other parameters.
High resolution test for large optics with sub-pixel phase retrieval method
Xiaojun Hu,
Shengyi Li,
Yulie Wu
Show abstract
For large mirror test, there is growing need to increase the spatial resolution of the test instrument, when testing large optics. A novel test method is introduced to achieve high spatial resolution based on phase retrieval method that splits each pixel of CCD into sub-pixels by numeric processing. Because the more images are captured, the more information of wave front is gathered to confirm the state of each sub-pixel, the sub-pixel phase retrieval needs multi-images and also more calculation power to process these images. Numerical experiments shows that more than 4 times of resolution of traditional phase retrieval method can be achieved by this method.
Effect of electric field on oriented poly(vinylidene fluoride) (PVDF) thin films prepared by vacuum evaporation
Show abstract
Thin oriented films of α phase PVDF were prepared by vacuum evaporation method. The technique of X-ray Diffraction and FTIR were used to analyze the crystalline microstructure of two types of α-form film. The thin oriented films have single pure α phase and the preferred crystalline orientation is on the (020) orientation paralleling to the substrate. The effect of electric field on crystal form of PVDF films during deposition has been studied in the presence of electric field during deposition process, in which the orientation is perpendicular to substrate. The diffraction pattern of PVDF shows that the intensity of diffraction peak decreases with the increase of DC voltage value, and increases with the increase of AC voltage value. The magnitude and direction of electric field have remarkable effect on crystal growth.
Study on automatic measurement of tiny-size
Show abstract
The computer vision technology is applied into automatic measurement of tiny-size like filament. The authors utilize digit image processing technology to analyze and research image data, extract edge contour of objects, consequently obtain information including edge position and dimension of objects. The information can be used to obtain practical dimension of objects after being calibrated and analyze objects' parameters and find out eligible objects.
3-D topography measurement by moire stripe
Show abstract
Using 3-D topography measurement of microelectronics Substrate as a background, the mechanism and method of accurately measured mechanical quantity through Moire stripe is studied. The paper also discusses the acquisition of Moire interference fringe image information, the analysis and process of Moire stripe image and key technological problems of how to reconstruct 3-D surface topography through Moire stripe information. This study provides non contact, high-speed and high-accuracy measurement techniques not only for microelectronics substrate but also for other information products (like shadow mask). It can be foreseen that this method has broad applications and theoretical instructions in engineering area.
Spatial coherence measurement of multiple coherent laser combination
Show abstract
Coherent combination of laser beam is an important and challenging area of laser science, and many researchers have demonstrated a lot of multiple laser-beam combining technologies and structures. In this paper, the coherent combining principle was discussed and a novel self-coherent-combining solid state laser based on corner cube cavity is reported, for which a corner cube was utilized as a terminal mirror. The authors found that the near-field intensity distribution profile of CCR laser was divided into six fan-shaped segments by dihedral angle lines and their images, while its far-field intensity distribution presenting good centralized profile as a strong peak surrounded symmetrically by six weaker peaks. In order to get quantitative coherence details of CCR lasers, spatial coherence of two conjugate laser beams were measured. The far-field distribution of the conjugate laser beams presented very clear interference pattern and the stripe contrast visibility was calculated as high as 0.74 indicating the coherence degree should be even more than 0.74.
Laser shaft alignment measurement model
Chang-tao Mo,
Changzheng Chen,
Xiang-lin Hou,
et al.
Show abstract
Laser beam's track which is on photosensitive surface of the a receiver will be closed curve, when driving shaft and the driven shaft rotate with same angular velocity and rotation direction. The coordinate of arbitrary point which is on the curve is decided by the relative position of two shafts. Basing on the viewpoint, a mathematic model of laser alignment is set up. By using a data acquisition system and a data processing model of laser alignment meter with single laser beam and a detector, and basing on the installation parameter of computer, the state parameter between two shafts can be obtained by more complicated calculation and correction. The correcting data of the four under chassis of the adjusted apparatus moving on the level and the vertical plane can be calculated. This will instruct us to move the apparatus to align the shafts.
Method of nonlinear correction of two-dimensional position sensitive detector
Changtao Mo,
Ming Wang,
Guoyu Zhang
Show abstract
The position sensitive detector (PSD) is photo-electronic sensor which can detect the position of a light spot incident on its surface. Many types of non-contact dynamic displacement monitoring instruments could be constructed using PSD. How to overcome the influence of non-linearity action is the most important problem to improve measuring precision and reliability of the instrument. The output characteristic of PSD is analyzed. It is found that the output response of sensor is non-linear when the measuring range is large. In this paper we propose a method for correcting non-linearity of PSD sensor based on high precision linearization sub-block integration neural network interpolation. By using conjugate gradient algorithm of neural network which have characteristic to approach arbitrary nonlinear function, the nonlinear mapping between detecting the voltage of sensor and the outputting results are obtained by training neural network under different nonlinear condition. Experiment results indicate that not only the influence of non-linearity is eliminated effectively, but also the output of nerve network is linear.
Research of data acquirement in NIR spectrometer based on SOPC
Show abstract
G9211 series InGaAs linear image sensors are developed by Hamamatsu Photonics, and its spectral response range is 900~1700 nm which is in the range of near infrared spectroscopy. This paper introduces a near infrared spectroscopy data collection system based on G9201 and Nios II, which is the 2nd generation soft IP CPU provided by Altera Corporation. With the help of DspBuilder, which is provided by Altera, the system can analyze the data in real-time with high efficiency. The system's communication is held USB1.1 and TCP/IP protocols. The collection and analysis of samples of the near infrared spectroscopy data on embedded system is implemented on this system as is needed to develop a compact and intelligent NIR spectrometer.
Pilot study on photonic crystal fiber Raman amplifier
Show abstract
Raman fiber amplifier (RFA) can be used for amplifying signals in all wavelength bands. To obtain flat Raman gain in considered wavelength range, we can use either more fiber amplifiers for different wave bands or more pump sources combined with appropriate pump powers at appropriate wavelengths. However, appropriate wavelengths and powers make the communication system complex and not easily controlled. Because of its ultra-wide band single mode operation, flexible structure design, their realization of high nonlinearity and overall controlled dispersion properties, photonic crystal fiber (PCF) is recognized as a novel class of fibers and a promising new kind of Raman gain medium. The larger nonlinear coefficient could be obtained by reducing mode area through its air hole microstructure region, thus leading to a greatly improved Raman gain coefficient. In this paper, we have modeled and simulated Raman gain properties of PCFs. Appropriate pump wavelengths and output powers are used as the multi-pump for PCFRAs. Through tuning the pump wavelengths and their output powers we can obtain the gain bandwidth of 40nm (from 1530nm to 1570nm) and the gain value is 14dB with ±0.5dB ripple.
Research on measurement technology for auto-stereoscopic display vision character based on CCD
Fayun Liang,
Hua Zhang,
Weibin Wang
Show abstract
Stereoscopic display is a human-machine complex system based on human being's stereo vision. The method to realize nakedness-eye stereoscopic display shows parallax image on screen and form individual view zone. According to optical character, a parameter "Stereo Degree" is put forward to measure stereoscopic effect. An equipment is researched and designed for measuring stereoscopic display vision character. The conclusion is verified by experiment, the position of independent view zone deduced from these experiments is an important reference when the display was used.
Intelligent lightening system of urban and rural road traffic based on pyroelectric infrared detector
Man-Xiang Miao
Show abstract
By using the photo-voltage characteristics of pyroelectric infrared detector to fulfill signal acquisition, the detecting signal is processed with the core of a single chip microprocessor AT89C51. AT89C51 controls the CAN bus controller SJA1000/transceiver 82C250 to structure CAN bus communication system to transmit data through serial interface MAX232 connected with PC. The intelligent lightening system of urban and rural road traffic was carried out. In this paper, its construction and part's methods of hardware and software design were introduced in detail.
Wavefront measurement based on active deflectometry
Show abstract
In this paper, a new wavefront measurement is proposed, which is based on active deflectormetry and phase-shift technique. The deflections of imaging rays caused by a phase object could be measured accurately with the phase-shift technique and a removable TFT flat panel to display both the horizontal and vertical sinusoidal intensity patterns respectively, and then the wavefront distribution could be calculated. When a phase object is placed between a display and a calibrated CCD camera, the intensity patterns will be distorted. The distortion can be measured, and another different distortion can be got by moving the display. Then the ray deflections can be measured as well as the gradients of phase shift caused by the object. Therefore the wavefront can be reconstructed. Experimental results show the feasibility of this method. Compared with other techniques, this technique is simpler, cheaper and more flexible.
Dynamic deformation measurement and analysis of active stressed lap using optical method
Show abstract
The active stressed lap is the heart of polishing process. A novel non-contact optical method of dynamic deformation measurement and analysis of an active stressed lap is put forward. This method, based on structured illumination, is able to record full-field information of the bending and rotating stressed lap dynamically and continuously, while its profile is changed under computer control, and restore the whole process of lap deformation varied with time at different position and rotating angle. It has been verified by experiments that this proposed method will be helpful to the opticians to ensure the stressed lap as expected.
Structural and optical properties of Al-doped ZnO films coated by RF magnetron sputtering
Yue-Bo Wu,
Bo Huang,
Liang-Tang Zhang,
et al.
Show abstract
The Al-doped ZnO (AZO) films were deposited on glass by RF magnetron sputtering under different sputtering power:
75W, 120W, 160W and 200W. During the films deposition, the other sputtering conditions were maintained constant.
The crystal structures of the AZO films were characterized and analyzed by X-ray diffraction. The surface morphologies
of the films were observed by SEM. The transmission spectra of the films were measured using a spectrophotometer
within the range from 200 to 800 nm at room temperature. The results indicate each of the films has a preferential c-axis
orientation and the grain size increases with the increase of sputtering power. All the films exhibit a high transmittance in
visible region and have sharp ultraviolet absorption characteristics.
Detection method and experimental study for pollutant content based on surface plasmon resonance biosensor
Show abstract
The principle of SPR biosensor is presented at the beginning of this paper. Then both direct assay for macromolecules and indirect assay (inhibition assay) for small molecules are introduced, which allow for high sensitive SPR detection of these two kinds of molecules. By combining some peripheral components including flow cell, multiposition valve, constant flowrate syringe pump and so on, a SPR biosensor system with an integrated miniature SPR sensor was designed and produced. Solutions of different concentrations of bovine serum albumin (BSA) were detected by making use of this system with the method of direct assay and a sensorgram of SPR resonance angle about different concentrations of BSA antibodies was generated. A calibration curve of BSA antibodies was also obtained. Solutions of different concentrations of estradiols were detected using inhibition assay. According to SPR resonance angle shift (ΔRU) corresponding to different concentrations of estradiols, a calibration curve was generated and the result was satisfying. For the sample of unknown concentration, once the resonance angle shift (ΔRU) is detected, the concentration can be calculated from the calibration curve.
Comparative study of surface roughness with power spectral density and multifractal spectrum
Show abstract
This paper presents a comparative studied of surface roughness. Samples were first measured by atomic force microscope (AFM). The acquired height data was then processed to calculate their power spectral density (PSD) and multi-fractal spectrum (MFS). The calculation results indicate that MFS of different samples with same sampling length differs significantly from each other, while the MFS of the same sample with different sampling length or different sampling position is quite similar. The calculation also shows that MFS is very sensitive to particles or scratches appeared on the surface. The PSD of the same data acquired from these samples are also presented for comparison. It is clear from the calculation results that the PSD curves vary with the sampling position and sampling length, thus makes the evaluation uncertain. No quantitative index available from PSD, only qualitative information obtained. Comparatively, MFS is better in description of a surface roughness.
Line-by-line trace gas absorption model and its application for NDIR gas detection technology
Show abstract
An accurate line-by-line trace gas absorption model is present in the paper. It is for mid-infrared band and can be used for the study and application of detecting trace gas (or pollution gas) in atmosphere. It is based on HITRAN molecular spectroscopic database. Spectral line shape, far wings, temperature correction and resolution are calculated. Infrared absorption characters of various gases in atmosphere can be simulated by the model. The algorithm details are described and the results calculated by the model are compared with that measured by Fourier transform infrared spectrometer. As an instance, model is applied for detector design of NDIR technology and the relationship between signal intensity of detectors and concentration of CO2/CO is simulated by the model. Available concentration range of detector is given by calculating results of the model.
Nonlinearity-reduced interferometer
Show abstract
Periodic nonlinearity is a systematic error limiting the accuracy of displacement measurements at the nanometer level. It results from many causes such as the frequency mixing, polarization mixing, polarization-frequency mixing, and the ghost reflections. An interferometer having accuracy in displacement measurement of less than one-nanometer is necessary in nanometrology. To meet the requirement, the periodic nonlinearity should be less than deep sub-nanometer. In this paper, a nonlinearity-reduced interferometry has been proposed. Both the linear- and straightness-interferometer were tested. The developed interferometer demonstrated of a residual nonlinearity less than 25 pm.
Research on the effect of phase mask to extend the depth of field of optical system
Show abstract
The technique of wavefront coding can extend the depth of field of incoherent optical systems in which the design of phase mask is very important. Several designs of phase mask are proposed in this paper, the MTFs (magnitude of optical transfer function) of these methods are deduced and the figures of MTFs are compared and discussed. The simulation results are presented that MTFs are insensitive to misfocus and never to be zero which would occur in traditional incoherent optical systems. Based on subjective evaluation and quantitative simulation results, we believe that special designof phase masks is effective to expand the depth of an incoherent optical system.
Laser scattering properties of rough spherical surfaces
Chun-ping Yang,
Jian Wu
Show abstract
An approximate model is developed to study the properties of laser scattering from a rough spherical surface based on a random facet model and the electromagnetic scattering theory. For actual spheres, for instance oilcan, its lateral correlation length is much longer than the incident laser wavelength, and its surface distribution is usually isotropic and conforms to Gaussian distribution. Hence, it is feasible to deal with scattering of the rough spherical surface with the random facet model. First, power scattered into a detective system can be denoted for every facet with the scattering model of a coarse plane corresponded to the isotropic Gaussian statistics. Second, total power received by the detective system should correspond to incoherent addition of power scattered into a far-field detector system by all facets. Here, an incident shadow function has been taken into account to exclude the contribution of the facets not being illuminated. Likewise, a scattering shadow function is introduced to exclude the contribution of the scattered light blocked by undulations of spherical surface. An unfolded factor has been taken into account in this model, too. Finally, to verify this model, the angular distribution of the scattering intensity in far field is calculated and analyzed under different cases. The results show that the scattering intensity is stronger in the backward than in other directions if the spherical surface is smooth, but if the spherical surface is rough to some extent, the incident laser power will be scattered to other direction and there is faint scattered intensity in forward direction concomitantly. We can use these properties to make remote sensing for spherical objects.
New calibration approach for light stripe sensor
Show abstract
A simple, flexible and real-time calibration method is proposed to solve the calibrating problems of line structure light sensor such as requirement of high accurate calibration model, complicated calibrating procedure and so on. First, a 2D calibration plane with tessellated pattern is placed at several arbitrary places in the measurement range of sensor, and the pictures of calibration board on these positions are recoded. The parameters of camera are estimated from these pictures. Secondly, the line structure light is turned on, and projected on the surface of calibration board. Several pictures are captured while the board is being moved along the direction of line structure light. Thirdly, the rotating matrixes and transform vectors between the local coordinates of these planes and the global coordinate of sensor are estimated. The global coordinates of the control points falling on the line structure light plane were calculated according to these matrixes and vectors. Finally, the model parameters of the sensor at working state are optimized with these control points. The cost of calibration equipment is greatly reduced and the calibrating procedure is simplified with the proposed approach. So it can promote the engineering applications of the line structure light sensor. It shows that this method is practical for surface measurement. The height error (RMS) of the measured object reaches 0.03mm in the region of 200mm x 150mm.
Three-dimensional digital imaging based on temporal phase unwrapping with parallel DSP
Show abstract
An embedded three-dimensional (3-D) digital imaging scheme with a parallel fixed-point digital signal processor (DSP) is presented, which is based on temporal phase unwrapping and DLP digital projection technique. This scheme utilizes an embedded hardware structure with aid of parallel DSP to realize a pipeline procedure of the automatic analysis of fringe patterns, fringe patterns generation, fringe projection, and data acquisition. The software pipeline is also adopted in the procedure phase demodulation and phase unwrapping. The time of phase reconstruction with five-step phase shift is 0.89s for 262144 coordinates, and the fringe image processing speed is up to 39.5 f/s (frames per second), so it can meet the need of video-rate fringe images processing. Experiment results show that this embedded DSP imaging system is fast, reliable, low power cost, and it will be suitable for a wide range of practical measurement application.
Calculation and analysis of the measurement of the focal length of a lens in a Fizeau interferometer with combination lenses
Show abstract
In this paper, the measurement method of long focal length in a Fizeau interferometer with combination lenses is stated. According to the principle of geometry optics, two focal length calculation formulae are deduced for the measurement method. The optimization of measurement parameter values is analyzed, and the optimized values of measurement parameters are selected. By analyzing the measurement error of the focal length needed to be measured, the permitted error ranges of measurement parameters are obtained for the optimization of parameters so as to meet the requirement of measurement accuracy of focal length (±0.1%). By means of analysis, it is obtained that the measurement method can meet the requirement (±0.1%) of measurement accuracy of long focal length of high power laser Facility.
Research on optimum cut direction of quartz transducer
Show abstract
Acousto-optic (AO) technology sprang up at the beginning of 1960s, after the naissance of laser. The electro-acoustic transducer is an important part of acousto-optic device (AOD), and quartz is an important crystal for making the transducer due to its good piezoelectric property. In this paper we calculated two kinds of acoustic velocities, non-strengthened acoustic velocities and strengthened acoustic velocities, for three kinds of acoustic modes, one longitudinal wave and two shear waves, in three coordinate planes of the quartz systematically using Christoffel equations. Then electromechanical coupling coefficients of every acoustic mode are calculated and curves of coefficients in three coordinate planes are pictured. Finally we determined the optimum cut direction of longitudinal wave and shear wave respectively. The results of this paper will play a directional role for the research of AOD.
Vectorial shearing interferometer with a high resolution phase shifter
Show abstract
Vectorial shearing interferometer has been used to measure small and large non-rotationally symmetrical wavefronts aberrations. This interferometric system encompasses large and differential wavefront displacements using a high accuracy rotation system incorporated in a Mach-Zehnder interferometer. The rotation system is based on the Risley prism arrangement and it is controlled with an electronic servomotor system by means of an auto-tuning algorithm. We present the servo-mechanical system, electronic interface and algorithms to control the performance of the high resolution rotation device that is used to control the wavefront phase shifting.
Approach using sparse bundle adjustment for system calibration of fringe projective 3D profile sensor
Show abstract
A new model-based system calibration approach to achieve optimal parameters of fringe projective 3D profile sensor is proposed, by modeling the projector as an inverse camera. The whole calibration procedure is divided into two steps: camera calibration and projector calibration. Jointly considering the relations among cameras and projector, a method of bundle adjustment suitable for the system is described. Not only the feature parameters described as homologous pairs of corresponding image points, but also the intrinsic parameters of projector and cameras shared by all views are considered for constructing the cost function. The lack of interaction among parameters for different features in multiple views results in underlying normal equations exhibiting a sparse block structure, which is exploited to obtain considerable computational benefits. The sparse Levenberg-Marquardt method is used as the last minimization means of bundle adjustment. Experiments are carried out for testing the convergence, efficiency and accuracy of the approach. The results show that within reasonable confidence interval the calibration accuracy is higher than that of the linear method. Even with the loss of feature information, the approach still works well and the results remain nearly the same.
Process, reliability test, and interfacial characterization for low temperature wafer direct bonding
Xiaohui Lin,
Tielin Shi,
Zirong Tang,
et al.
Show abstract
Low Temperature Wafer Direct Bonding (LTWDB), as an enabling technology, can be used in preparation of MEMS material (SOI) and manufacturing of multi-layer solar cells. In the present experiment, LTWDB was achieved by surface activation method using SPM and RCA-1 solutions. The main mechanism is relevant to the high oxidizability of SPM solution and surface cleaning, activation ability of RCA-1 solution. Especially, the preparation and usage of RCA-1 were improved to greatly enhance its activation effect. For reliability tests, tensile strength tests were performed and decrease was found after thermal-cooling cycle treatment. Besides infrared system and SEM scanning system was employed to exam the interfacial characterization of the bonded wafers. Infrared system was used to observe the bonding wave when contacting two wafers under normal environment. Interface with relatively high bond rate and interfacial uniformity could also be observed under infrared transmission system. It is demonstrated to be one of the most convenient ways to test the quality of bonded pairs. Besides, SEM was used to further inspect the nano-scale intermediate layers. Two closely contacted wafers with the intermediate layers' thicknesses around 120nm could be observed. Bonded pairs with thinner intermediate layers are characterized by higher bond strength.
Research of laser Doppler velocimetry based on DSPs
Show abstract
This paper analyzes and compares existing variety of LDV technologies. According to existing LDV's deficiencies such as limited signals processing ability, poor adaptability and low precision, a new design scheme of LDV based on digital signal processing is introduced in this article. Doppler signal processing systems processes the spectrum by DSP. The system consists of a filter, a wave detector, an A/D converter and buffer. DSP system samples digital signals and performs Fourier Transform, and the information of velocity is obtained. To achieve a high signal to noise ratio (SNR), many signal processing techniques are applied, such as inserting zero, signal window, the algorithm of periodic diagrams based on FFT and the algorithm of approaching peak value, all of this highly improve the noise adaptivity. In recent years, the spectrum zooming technology is developed quickly, the algorithm of Zoom-FFT based on complex modulation improves the analysis precision, calculation efficiency, resolution and flexibility effectively. In this paper, the time domain sampled signals are windowed firstly, then the zooming analysis via Zoom-FFT algorithm is implemented, and at last,the energy Centrobaric rectifying algorithm is applied to do further estimation. Simulation results indicated that the algorithm has many merits, such as anti-jamming, high accuracy and a small amount of computation.
Research on centralized interlocking monitoring system of OCS switches based on optical communication
Show abstract
It is the trend to realize OCS (Overhead Contact System) switches' centralized interlocking monitoring with the development of electrified railway. According to extensive investigation and study on the situation at home and abroad, this centralized interlocking monitoring system of OCS switches based on FSO (Free Space Optical communication) was developed. In this paper, the system structure and working principle are described in detail, the design of relevant hardware and software is given, and the control of FSO by local center is especially discussed. The system runs well during test, and it has bright prospect of application and popularization.
Research on the dynamic detection system for detecting the height of contact wire
Show abstract
The height of contact wire is one of the important technical parameter of OCS (Overhead Contact System) in electric railway. The device introduced in this paper is installed on the operating electric locomotives, and the height of the contact wire can be detected in real-time. In this paper, the system structure, working principle, installation and mechanical design are all introduced in detail. The precision is analyzed; the applied situation and the detecting results are given as well.
Algorithm for computation of off-axis aspheric surface parameters
Shu Li,
Yuegang Fu
Show abstract
To help the fabrication of off-axis aspheric section, we present an algorithm to calculate current surface parameters, such as lateral displacement, tilt angle and paraxial radius. This algorithm bases on the equation for conic aspheric surface and general geometry transformation matrix of three-dimension graphics, and deduces an equation about the coordinate and surface parameters. In order to solve this problem, we developed a new software based on Conjugate Direction Method to minimize the RMS of deviation. By using the software, the efficiency of test increases obviously and the accuracy of test is perfect because this method can avoid the effect of transfer and rotation of surface data.
Image fusion algorithm for rock fracture detection using wavelet transform
Show abstract
The authors study large panchromatic images and ultraviolet (UV) images. The paper presents an image fusion algorithm based on wavelet transform. Because the panchromatic image contains the detail of rock surface, we select larger low frequency coefficient. At the same time, ultraviolet images contain the important information of rock edge with less detail, so we select larger high frequency coefficient, and use wavelet modulus maximum to find the localizer of UV image edge, use the localizer to enhance the fusion image using panchromatic image. Experiment results show that the fusion algorithm is satisfactory.
Analysis of structure and control of the loop-locked ultra-precise 2D flexible hinge stage for optical measurement
Show abstract
Although PZT driving stage is a practical and widely used component in optical scanning measurement, its creep, hysteresis, poor long-term stability and the vibration of stage hindered the promotion in driving and positioning accuracy. Based on feedback control, the stage can have nanometer level driving accuracy. For attaching the displacement feedback sensor, a special structure that is called expanded hinge is designed. For getting higher sensitivity, a shallow groove is cut in it. In order to confirm the effect of the additional structure on the performance of the stage, the finite element software is employed, the analysis had been completed, and the simulated results are presented. With the vibration model of the 2D flexible hinge stage, the mathematic model of the vibration control can be achieved, and the PID control system is set up. After the sensors are carefully attached to the corresponding spot and the processing circuit is completed, the simulation and test of the overall performance of the stage can be executed.
Analysis of the measurement error of fibers' position for LAMOST
Show abstract
In a fiber positioning system, geometrical coordinates of fibers need to be measured in order to verify the precision of fiber positioning. So a measurement system based on area CCD is built up. This system consists of an area CCD sensor, a frame grabber, a lens and a computer. Photogrammetric measurement has a high position detection precision for static objects and its measurement precision could be about 5 microns. Fibers are installed in the positioning units and can point to any point in the circular area with 33mm diameter. So not only temperature, vibration, lens aberration but also F number, lamp-house and speckle status will probably cause measuring error. Through lots of experiments, different factors which influence to fibers' position measurement precision are analyzed. From the experimental data of distances between fibers, whose actual values are unchangeable. It could be seen that measurement values of distances have a change at least 12 microns through Photogrammetric measurement when fibers rotate to different angles. Finally the measurement error is analyzed briefly.
Research on a real-time scanning tunneling microscope data acquisition system (Notice of Removal)
Chang Xu,
Baoping Xiao,
Lijun Xu
Show abstract
This paper (67233A) was removed from the SPIE Digital Library on 13 April 2010 to discovery of plagiarism. As stated in the SPIE Guidelines for Professional Conduct and Publishing Ethics, SPIE defines plagiarism as the reuse of someone else's prior ideas, processes, results, or words without explicit attribution of the original author and source, or falsely representing someone else's work as one's own. SPIE considers plagiarism in any form, at any level, to be unacceptable and a serious breach of professional conduct. It is SPIE policy to remove such papers and to take appropriate corrective or disciplinary action against the offending author(s).
Study on band gap of photonic crystals with heterostructure
Show abstract
The size of absolute band gap s in photonic crystals can be increased by reducing the lattice symmetry. Using this methods design the model of Photonic Crystals with heterostructure. In this paper a new structure by adding different rods into the unit cell of square lattices is explored, and we also consider the structure which overlays the glide symmetry lattice structure with single rod square lattice. Its band gap was calculated by the finite difference time domain method. Numerical analysis shows that the size of absolute band gap is enlarged in this way.
Fabrication of MTF measurement system for a mobile phone lens using multi-square objects
Show abstract
The mobile phone market grows rapidly and the performance estimation about camera module is required. Accordingly, we fabricate the MTF measurement system for a mobile phone lens having extremely small diameter and large f-number. The objective lens with the magnification of X20 for MTF measurement for high resolution lens and a detector of CCD that is pixel size of 7.4 um are adapted to the system. Also, the CCD is translated by using a linear motor to reduce measurement errors. The measurement lens is placed at the most suitable imaging point by a precise auto-focusing motor. The measuring equipment which we developed for off-axis MTF measurement of a mobile phone lens used the multi-square objects. The square objects of measuring equipment are arranged a unit in the on-axis and total 12 units (0.3 field: 4 units, 0.5 field: 4 units, 0.7 field: 4 units) in the off-axis. When the measurement is started, the linear motors of signal detection part are transferred from on-axis to off-axis. And a detected signals from the each square objects are used for MTF measurement. System driver and MTF measure are using application program that developed us. This software can be measure the on-axis and the off-axis sequentially. In addition to that it did optimization of motor transfer for measurement time shortening.
Imaging resolution of digital holographic microscopy with premagnification
Show abstract
The pre-magnification digital holography with a microscopic objective (MO) has become an important mean for imaging and measuring of microscopic objects. Based on Fresnel diffraction theory, the point spread function of digital off-axis Fresnel holographic system with pre-magnification is firstly deduced in detail. The lateral resolution of this imaging system is then analyzed. The amplitude distributions of the point spread functions of the MO, the holographic CCD and the whole imaging system are simulated respectively. Then, the matching requirements between MO and the holographic CCD are discussed. Some ambiguities about the resolution limitation in existing literatures are clarified. The results show that only when the image resolution of the holographic CCD is not below the imaging resolution of the MO, the resolution of overall system is dependent on the numerical aperture of the MO. Otherwise, it is dependent on the numerical aperture of the CCD. It is optimum to make the imaging resolution of the MO approach its limitation and be equal to or less than the resolution of the holographic CCD a little. The simulation results verify the validities of the theoretical analysis.
Interferometric total thickness variation measurement of glass wafer
Show abstract
Total thickness variation (TTV) is one of the important specifications of glass wafer. Glass wafers are thin and transparent parallel plates. In order to measure a flat surface by interferometer, at least one reference flat of same size is required. And the interference between two reflected wavefronts by the front and rear surfaces of the glass wafer also exists. Therefore interferometric measurements of thin glass wafers are not easy. So TTV is mainly measured not by interferometer, but by thickness gauge devices. But these devices measure only the TTV of several positions of glass wafer and don't measure the whole area. To measure the whole area or sufficient points, it requires more time. We developed a relatively simple and inexpensive interferometric TTV measurement method using Haidinger interferometer. This method can be applied to large glass wafers without large reference flat.
Laser writing system for test of large aspheric surfaces
Show abstract
KRISS Space Optics Research Center has tested large aspheric surfaces by using interferometry and a series of computer-generated hologram (CGH). In this case it is necessary to fabricate various CGHs in the laboratory level. To address this purpose we are developing and improving a simple and precise laser writing system which uses a cylindrical or circular coordinate. In our system 300 mm diameter CGH can be fabricated with 0.8 μm spatial resolution in radial direction. The writing source Ar+ laser is stabilized by intensity feedback, and gives us approximately 800 mW after the stabilization process at 457.9 nm wavelength. The stabilized beam power is controlled again to make 256 different intensity levels. We also used an auto-focusing technique with astigmatic lenses for the purpose of focusing the writing beam on the material surface.
Structural damage detection with a stabilized optic fiber Fabry-Perot acoustic emission sensor system
Show abstract
A fiber-optic Fabry-Perot (F-P) acoustic emission (AE) sensor system based on the improved double wavelength stabilization technique is developed, which can be used to detect the structural damage. The work principle of system is analyzed, and the optimum double wavelength stabilizing model is established. An optical passive device, dense wavelength division multiplexer (DWDM), is used to generate two quadrature phase-shifted output signals. The central operating wavelength of DWDM is calculated by the optimum design method. The performance of developed sensor system is verified by two preliminary tests. One is a test on the stabilization of fiber-optic F-P sensor operating point, the other is the acoustic measurement generated by the impact and pencil lead breaking. One test result indicates that this stabilization means is totally passive and offers a high resolution, and the maximum quadrature error between dual output signals is 11% when the length of F-P cavity changes from 0 to 2 um. Thus the stabilization method can overcome an intrinsic disadvantage of signal attenuation and satisfy the stabilization need of optical fiber F-P AE sensor operating point. Another test result demonstrates that this sensor system successfully detects acoustic signals generated by impact and pencil lead breaking on the surface of an aluminium plate and it is promising for the detection of structural damage.
Terahertz technology and application for explosives detection
Show abstract
Terahertz (THz) radiation, which occupies a large portion of the electromagnetic spectrum between infrared and microwave bands, offers innovations imaging and sensing technologies that can provide information not available through conventional methods such as microwave, X-ray imaging and NMR(nuclear magnetic resonance). T-ray imaging can give not only the density picture but also the phase information within the frequency domain. T-ray imaging has several advantages over other sensing and imaging techniques, so it has many important scientific, industrial and medical applications. In this paper, we study the feasibility of using THz sensing and imaging for mine detection. The principal features of THz radiation and its unique advantage in mine detection are investigated. Some difficult issues, which are not resolved yet, are discussed. The military applications and development trend of the THz spectroscopy are briefly forecasted.
Study on the movement measurement for an objective lens actuator in optical pickup
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This paper deals with the actuator movement measurement for objective lens actuator in optical pickup. An optical pickup is an optical apparatus to record and/or reproduce information from an optical disc, and move in a radial direction on the optical disc. The objective lens actuator helps move an objective lens in a tracking direction, a focusing direction, and/or a tilting direction, spot the laser beam on a correct portion of the optical disc. It basically carries out tracking and focusing movements, i.e., a biaxial movement. For high recording density media, the optical pickup actuator requires a triaxial or quadriaxial movement including a tilting movement in addition to the existing biaxial movement. For information recording and/or reproducing correctly, the movement range of the actuator should be proper to accurately follow the disc deviation. Alternative methods of movement measurement have been proposed. One method employed now uses a plane plate reflecting laser beam which describes the movement. It requires two laser devices for tracking direction and the focusing direction measurement respectively. Here we propose a method for describing the tracking and focusing movements on one laser device. In this method an external cone is used, with the same weight as the objective lens. It could reflect laser beam back to the linear CCD. The diameter of the external cone base is equal to that of the objective, which is crucial for a stable placement. The ratio of height to width of the external cone is designed and optimized, so that to satisfy the accuracy of the movement measurement and minimize the device. Measurement with this method has proved satisfactory for certain CD/DVD optical pickup.
Comparative study of two measurements of micro-deformation field with optical method
Show abstract
Two digital optical methods to measure micro-deformation field are investigated. One is digital shearography measurement, the other is reflecting digital holography interferometry. Corresponding experiments are done based on both methods mentioned above, and the stripe pattens are gained by using digital image processing. A simple and quick method to interpret stripe pattens is presented and corresponding results are also obtained.
Capillary electrophoresis microchip detecting system based on embedded optical fiber
Weiping Yan,
Yuanyuan Li,
Lingzhi Ma
Show abstract
Microchip capillary electrophoresis(CE) has been recognized as a powerful tool for biochemical analyses due to its smaller size, faster separation and lower sample requirement. According to the principle of laser-induced fluorescence, the detecting system of CE microchip embedded optical fiber is discussed in this paper as well as its small volume and simple detection optical circuit. The system was composed with semiconductor laser (532nm), high voltage control system, photon counter, PC and CE chip embedded optical fibers. With the constructed detection system, different samples and different concentrations were detected, including Rhodamine B, Rhodamine 6G, and mingling solution of Rhodamine B and Rhodamine 6G. The lowest detected concentration is 1×10-6mol/L for Rhodamine B, and 1×10-5mol/L for Rhodamine 6G, respectively. The separation of the mingling solution of Rhodamine B and Rhodamine 6G was completed, whose concentration were both about 1×10-4mol/L. The results show that the constructed detection system possesses some advantages, such as compact structure, higher sensitivity and repetition, which are beneficial to the development of microminiaturization and integration of micro CE chip.
Design of compensator for large relative aperture aspherical surface
Gui-ping Shen
Show abstract
Firstly, the parameters of relative large aperture aspherical surface to betested are described. The large aperture aspherical surface is very difficult to be tested. Then two kinds of null-test methods are used. One is null test with parallel ligh. The other is the refractive Offner compensating system. The solving process of the preliminary structure parameters of the compensator is discussed. Through comparison of two methods, we choose the method which is more appropriate to test large relative aperture aspherical surface.The consequence after optimization by ZEMAX is also given in the paper.
Interferometric measurements of mid-spatial scale surface irregularities
Show abstract
A simple method which can be used to map mid-spatial scale surface irregularities with high signal noise ratio is described. Two major sources of errors are analyzed and removed. One is the contributions of small-scale irregularities of the reference surface, which are subtracted by shifting the test surface laterally by a distance. The other is the spurious response of CCD, which is removed by interpolation function. The presented method is verified by simulations and experiments. It shows that it can measure mid-spatial scale surface irregularities exactly and smaller scale surface irregularities can be obtained by making measurement for a series of the lateral shifting values corresponding to one-half of the pixel space on CCD.
Design and research on the optical sensor of dissolved oxygen in water based on fluorescence quenching
Li Sun,
Wen-yuan Dai,
Jian Bao,
et al.
Show abstract
A novel optical technology for on-line monitoring of DO (Dissolved Oxygen) is reported. As a DO sensor in water, Ruthenium (II) complex (Ru(ph2phen)2+3) adsorbed on silica 60 gel particles emitted strong pink fluorescence steadily when a 470 nm wavelength blue LED (light-emitting diode) shined. The fluorescence could be quenched with molecule oxygen sufficiently; the higher DO concentration is, the weaker fluorescence intensity becomes, and the dynamic quenching processes were described by Stern-Volmer formula. Through reasonable correction and calculation, the concentration parameter of DO in water would be got. In laboratory, we used the optical sensor to measure DO concentration with oxygen-free water, oxygen-saturated water and natural water samples, and also researched the change of DO concentration in different temperatures. Experimental results show that measure range of the sensor is 0 ~ 20mg/L, and the accuracy is less than ±0.2mg. The sensor can be used on line monitoring of DO in water.
Testing smooth surface characteristics based on thermal infrared polarization
Li Sun,
Zhen Wang,
Jin Hong,
et al.
Show abstract
A novel optical method was provided to test the sample surface using a thermal polarimeter. The polarimeter consists of a rotary polarization filter and a thermal imaging system that is based on an uncooled focal plane array (UFPA) in long wave infrared (LWIR, 8~12μm) band. The thermal infrared polarization images of a Vernier caliper head were taken by a rotary polarizing filter at angles of 0°, 60°, 120° degrees. These images were saved into a computer and were calculated with Stokes parameter formulas to produce digital images of Stokes parameters I, Q and U, degree of linear polarization and direction of polarization. These images clearly show the difference between different areas of Vernier caliper, and this difference is not obtainable from the intensity images. Experimental results show that the introduced method can extract surface roughness information from thermal images and can distinguish different surface characteristics quickly.
Application research of vision technology in automobile radio panel measurement system
Show abstract
This automobile radio panel measurement system can monitor the quality of automobile radio panel's VFD and LCD characters through making different parts' image templates with some image processing techniques. The previous system only powers the panel and measures the quality of the panel by eyes. This system takes the place of previous system and realizes the monitoring system's flexibility. In order to improve the system's stability, this paper analyses the characteristics of different partitions of VFD and LCD panel by some experiments and put forward an image processing method by synthesizing several image processing techniques.
NETD test of high-sensitivity infrared camera
Show abstract
Infrared camera has more and more application in military, judicature, rescue, industry, hospital and science. Nowadays
the NETD (Noise Equivalent Temperature Difference) of high-sensitivity cooled infrared camera is less than 10 mK. If
we test the NETD from the analog video output port of infrared camera using 8-bit and 10-bit ADC frame grabber, the
NETD accuracy is 7.81 mK and 2.76 mK which correspond to relative error 78.7% and 27.6% for a 10 mK NETD
infrared camera. Such kind of accuracy is obviously not proper for the performance evaluation of high-sensitivity
infrared camera with NETD less than 10 mK. The NETD test accuracy can be improved by increasing the effective bit
number of the ADC of frame grabber. The quantization error of ADC of frame grabber has become the main factor
which contributes most to the NETD error of the high-sensitivity infrared camera. It is difficult to evaluate the electrooptical
performance of the high-sensitivity infrared camera through its analog video.
Although the NETD test accuracy can be improved by reducing the linear temperature range or increasing the effective
bits of the ADC of frame grabber under analog video interface test condition, it is difficult to meet the test needs. But
under the 14 bits digital video interface test condition and 1 K linear range, the NETD test accuracy of 0.24 mK can be
achieved. The NETD accuracy can be also improved by reducing the linear temperature range. The NETD test accuracy
can be 0.488 mK through 14-bit digital video under 2 K linear temperature range and its relative error equals 4.9% for a
10 mK NETD high-sensitivity infrared camera which meets the requirement. The test result through the digital video
port of an infrared camera shows that the test result through digital video port matches with its nominal value. This
necessitates the need of digital video interface of high-sensitivity infrared camera in NETD test in order to evaluate its performance accuracy.
Research of surface acoustic wave acousto-electro-optic effect
Show abstract
In this paper a strengthened acousto-optic (AO) coefficient of piezoelectric crystal is proposed. It shows the influences of AO effect, electro-optic (EO) effect and piezoelectric effect in piezoelectric crystal. Through correcting acoustic momentum mismatch into sum of the acoustic and electric momentum mismatch, the coupled wave equation group of the surface acoustic wave (SAW) AO effect can be changed as that of SAW acousto-electro-optic (AEO) effect. A diffraction efficiency formula of SAW AEO effect is given through solving the equation group. The formula indicates that the diffraction efficiency is related to power of SAW, acoustic frequency deviation and direct current (DC) voltage. We designed and manufactured a SAW AEO device using Lithium Niobate (LN). Some curves of relative diffracted efficiency vs power of electric signals driving the device, acoustic frequency deviation and DC voltage are measured. Experimental results are consistent with theory. SAW AEO device can be used as a deflector or modulator. When it is used as deflector, its bandwidth is wider than that of SAW AO deflector. When it is used as modulator, its center frequency can be changed. SAW AEO device has smaller volume, less energy consume and is easy to integrate. It can be used in optic communication and real time signal processing, for example correlation, convolution, spectrum analysis and optic vector calculation and so on.
Radar and infrared data fusion algorithm based on fuzzy-neural network
Feng Han,
Wan Hai Yang
Show abstract
In modern war, the war field environment is complex and interfere is heavy, single mode weapon can not meet the military need. Multi-mode guiding weapon has some advantages for its multi-sensor data fusion. Radar and Infrared data fusion has been widely studied due to its implementation of complementary information, improvement of target tracking and enhancement of system viability. During fusing radar and infrared data under the condition of radar-infrared dual mode guidance, there is a problem that radar data is asynchronous with infrared data. The infrared measurement data is fused first to keep synchronous with the radar measurement data. The processed data is transmitted to the central Fuzzy-neutral network (FNN) data fusion central, which is employed to decrease the influence of the uncertainty of sensor state on fusion performance. A fused estimation of target is formed. Simulation result demonstrates that this method can improve the stability and reliability of fusion.
Measurement of paraboloid surface workpiece with zero error sum
Show abstract
According to the existed method of positioning paraboloid surface workpiece for measuring its shape accuracy, this paper proposes a new method of positioning paraboloid surface workpiece with zero error sums. The key idea of new method is to consider whole workpiece surface comprehensively, which can appreciate whole workpiece surface reasonably, objectively and entirely. It is different from former measuring methods mainly considering several points with big errors. The new method is important for elements used in a optical system, since in optical system the main factors of affecting optical system characteristic are not only several points with big errors on optical element surface, but also the whole surface. It is favorable to improve workpiece surface shape accuracy and its optical characteristics. Its principle not only can be used in measuring paraboloid but also for measuring other aspheric surface.
Primary study on ellipsometry of large roughness surface
Show abstract
Based on the method of space filtering, a subassembly of space filter consisting of lens and filter is introduced and a conventional null ellipsometer has been improved to measure large roughness surface and film with large roughness interface. From theory, the possibility of using space filter in null ellipsometer to get ellipsometric parameters of large roughness surfaces corresponding to the smooth surface is analyzed, and primary experiment is carried out. Experiment results show that the improved null ellipsometer can obtain preferable repeatability and accuracy of optical parameters of large roughness surface and film with large roughness interface.
Real-time monitoring of thin films' optical thickness at shut-turning point with fuzzy logic
Show abstract
Optical filters can be used in nearly every field from land to space. To get good performance optical filter, it is important to measure and control the film thickness of every layer on the substrate. There are many methods to monitor thin films' thickness in real-time. The most important one is the optical monitoring techniques. To avoid changing monitoring substrate frequently, we usually change the monitoring wavelength, and judge the film thickness of every layer at shut-turning point of the electric signal that represents the real-time film thickness. In the same time, Computer can be used to auto count the number of the turning point, then shut the electric source and the baffle when the counted number of the turning point arrives at the setting one. The electric signal which represents the real-time film thickness is affected by many aspects, such as optical noise, electric noise deposit rate and etc. It is not easy to judge the turning point accurately. Hence, it is useful to apply Fuzzy logic to judge the Shut-turning point of each layer in the process of manufacturing the optical filters. We design a fuzzy controller for thin film thickness monitoring which considered about both film thickness deposit rate and noise. A table for the shut-turning point judgment is set up in fuzzy logic. Then we can use computer to judge the turning point by looking up the table in real-time. This monitoring system has been applied in many projects to manufacture optical filters and got good results. Therefore, real-time monitoring film thickness using fuzzy logic is a good technique for film thickness monitoring.
Research on effects of phase error in phase-shifting interferometer
Show abstract
Referring to phase-shifting interferometry technology, the phase shifting error from the phase shifter is the main factor that directly affects the measurement accuracy of the phase shifting interferometer. In this paper, the resources and sorts of phase shifting error were introduction, and some methods to eliminate errors were mentioned. Based on the theory of phase shifting interferometry, the effects of phase shifting error were analyzed in detail. The Liquid Crystal Display (LCD) as a new shifter has advantage as that the phase shifting can be controlled digitally without any mechanical moving and rotating element. By changing coded image displayed on LCD, the phase shifting in measuring system was induced. LCD's phase modulation characteristic was analyzed in theory and tested. Based on Fourier transform, the effect model of phase error coming from LCD was established in four-step phase shifting interferometry. And the error range was obtained. In order to reduce error, a new error compensation algorithm was put forward. With this method, the error can be obtained by process interferogram. The interferogram can be compensated, and the measurement results can be obtained by four-step phase shifting interferogram. Theoretical analysis and simulation results demonstrate the feasibility of this approach to improve measurement accuracy.
Research on moire fringe information extraction based on warpage measurement
Show abstract
Warpage measurement of PWB board and BGA package is considered as the most popular but difficult issue in microelectronic fabrication. Ordinary measuring method cannot afford the requirement of direct observation, efficiency, immediacy, high-precision as well as low cost. Moire fringe is a kind of interference pattern by which we are able to measure the flatness of surface of an object. This paper mainly concentrates on how to extract the information of effective shadow moire fringes by using digital image processing technique. It presents some algorithms applied to moire fringe image processing, such as preliminary extraction algorithm of moire fringes, intensity enhancing algorithm of fringe, fringe thinning algorithm, removal of the forficate fringe etc. In the end, the three-dimensional image from data of the two-dimensional fringe matrix has been drawn. Experiment result shows the effect of methods for extracting effective moire fringes.
High-resolution digital holography for shape measurement of microscopic object
Show abstract
Digital holography is particularly well suited for characterization of microstructure such as surface shape, surface nanostructures and surface roughness. The direct availability of both amplitude and phase information offers a range of versatile processing techniques that can be applied to complex field data, including phase imaging, which is particularly straightforward in digital holography. Based on digital off-axis lensless Fourier transform holographic configuration, the principle of topography by digital holography is analyzed. The wavefront deformation created by numerical Fresnel reconstruction is then studied. Thus the model of phase mask which is a parabolic function and related to the recording parameters is built. The phase mask can be obtained automatically by using digital hologram itself to evaluate automatically and accurately the values of the parameters involved by a curve-fitting procedures applied to the phase data extracted along two profiles, which are defined in the region where sample contributions are constant. The reconstructed wave field can be simply obtained by multiplying the phase mask with Fourier transform of the hologram. Both theoretical analysis and the simulation results show that the procedure proposed by Colomb is more suitable for phase reconstruction of digital off-axis lensless Fourier transform holography. Moreover, the correcting procedure can be applied to compensate high-order aberrations.
Research on temperature and strain characteristics of metallized FBG
Benyu Wang,
Weiping Yan,
Rensheng Shen,
et al.
Show abstract
Metallized fiber Bragg grating can improve bonding performance between metal material and fiber Bragg grating, protect the sensor, improve stability and prolong the lifespan of the sensor. The characteristics of temperature and strain of metallized fiber Bragg grating are studied in this paper. By using a thermostat, a good linearity of temperature characteristic of MFBG was achieved and its correlative coefficient reached 99.95%. A high precision displacement set driven by stepping motor was used to move the free end of the metal cantilever beam with uniform strength which was adopted to tune the metallized fiber Bragg grating, a good linearity was obtained, and its correlative coefficients was 99.96%.
Sensitivity of magneto-optic method for measuring beat-length of high birefringence optical fiber
Show abstract
Examined is the influence by input state of polarization and analyzing scheme on sensitivity in the measurement system of beat length that relies on magneto-optic modulation technique in which the magnetic gap and intensity of magnetic field have been given. Through theoretic analysis and experimental study, it is found that there are three experiment schemes getting maximum sensitivity. First, the polarization direction of the input linearly polarized light is at θ = 00 or 900 to the birefringence fast axis of e fiber, at the same time, the two analyzing axes of Wollaston prism are at γ = 450 to the birefringence fast or slow axis of fiber. Second, the polarization direction of input linearly polarized light is at θ = 450, and γ = 00 or 900. Third, the input light beam is circular polarized light, at the same time, γ = 00 or 900. The sensitivity under three cases is approximately equal, but the third scheme needn't pinpoint the direction of birefringence axis of fiber, which makes the experiment more convenient and avoid the measurement error caused by the adjustment of angle.
Characterization of curved composite structure using laser infrared photothermal radiometry
Show abstract
The effects of curved-surface of both cylindrical and spherical samples with either a 2-layer structure (thin-film coating) or a continuous gradient structure (case hardened surface) are investigated. By appropriate signal processing, it is found theoretically that the curvature effect of both cylindrical and spherical samples can be eliminated under certain conditions and the PTR signal from the curved composite sample can be equivalent to a flat surface with same structure.
Photovoltaic effect of different thickness vanadium oxide thin film
Show abstract
Vanadium oxide thin films of different thickness were deposited on P (100) silicon substrates with silicon nitride thin film layer by reactive DC magnetron sputtering method. The current-voltage (I-V) curves of the samples measured in dark environment and different intensity of light environments showed that photovoltaic effect happened when the films exposed on visible light environments. Square resistance (Rs) and temperature coefficient of square resistance (TCRs) of vanadium oxide thin films were also tested in dark and light environment respectively, and the results demonstrated that the Rs was reduced and TCRs was enhanced when vanadium oxide thin films are exposed on light. Such effects changes with the variation of thickness of vanadium oxide thin films.
Application of two-frequency laser interferometer in dynamic calibrating of long displacement sensor
Wanfu Dong,
Bin Wu,
Fuchun Sun
Show abstract
Difficulties of automatic calibration for long displacement sensors have been overcome by applying two-frequency laser interferometer with two-longitudinal modes for standard displacement. High efficient automatic calibration has been achieved for long displacement sensor of 500mm. The total measuring uncertainty of the system is less than 2μm. The speed of dynamic measurement can be more than 20mm/s. Main work of the calibration is automatically completed by controlling the micro-computer system.
New photoelectric method for inside cylindricity measurement
Houyun Yu,
Zhuanping Zhao,
Ye Zhao,
et al.
Show abstract
Cylindricity is an important parameter in the evaluation for a cylindraceous workpiece. It has a direct effect on the precision of assembly and rotation. However it is difficult to carry out inside cylindricity measurement for a large workpiece (length: 2~3m, diameter >200mm), in which the spindle's straightness and measuring table's motion error deserve consideration. In this paper, a new error separation method is presented based on the application of precise photoelectric inspecting technique. And the two errors will be directly measured according to the deviation of facula. During the measurement, the workpiece is installed erectly on the base to minimize its distortion. Laser collimation initializes the measuring needle and gives real-time state of the measuring table. Two kinds of coordinates are used for error compensation, i.e. absolute and imaging coordinates. In the end, the least squares cylinder is used to calculate the cylindricity after all point data of each section are modified. Overall structure design and detailed measuring steps are also listed. Thus, the models of error compensation and cylindricity evaluation are obtained. Simulation results prove them correct with a satisfying precision.
Demodulation method of active homodyne laser vibration measurement system based on DSP
Show abstract
The demodulation method of active homodyne laser nanometer vibration measurement system based on digital signal processing (DSP) system is presented. In this paper, the software and hardware designs of low-frequency nanometer vibration measurement system is demonstrated based on the technology of phase generated carrier (PGC). The key technique of PGC based on DSP includes the following aspects: the choice of carrier frequency and the modulation depth of phase are expounded for the need of high sensitivity detection and large dynamic range; the designs of sampling frequency and anti-aliasing filter are introduced. Experiment result indicates that using digital signal processor chip as the core signal processing component has more advantages than analog system: the intrinsic direct current offset from temperature shifting of analog PGC circuit is eliminated; the disturbance of low frequency noise is suppressed; the systemic adaptability and the ability of anti-jamming are improved; besides, this system is easy to be miniaturization. This detecting system can be used for measuring weak vibration of nanometer measurement with frequency ranging from 10 to 100Hz.The result shows that amplitude-detecting resolving power is greater than 0.1nm(value of peak-peak) and the largest detectable amplitude is 10μm. It is a promising practical demodulation scheme for low frequency weak vibration measurement.
Spectral resolution of space-borne Fourier transform spectrometer
Show abstract
One of infrared remote sensing instruments carried by FY-4 meteorology satellite is a space-borne Fourier Transform Spectrometer (SBFTS). It acquires temperature, pressure and humidity of atmosphere on geostationary orbit, and supplies the valuable weather data for future numerical weather prediction. It uses a 16x4 plane array rectangular detector, so it can measure the spectra and spatial image simultaneously. The maximum optical path difference of the SBFTS is 0.8cm. Objective: This paper's mainly analyses the three factors (maximum optical path difference, off axes detectors, the tilt angle of the moving mirror) that influence spectral resolution of SBFTS and convinces through experiment. Methods: First, the three primary factors that will influence the instrument line shape (ILS) are discussed here. The ILS is deduced when the three factors are taken into account separately. The final function of ILS is the convolution of the three parts. And the spectral resolution is the half width of the ILS. The gases NH3 and CO are used to detect the ILS of the instrument in the long wave band and middle wave band separately. Their absorption line shape is Lorentz distribution in atmospheric pressure and room temperature. Now the absorption line shape of the gases and the ILS are given. They can be combined to the instrument detecting line shape theoretically. Finally it is compared with the line shape that is really detected by the instrument using gas cell methodology. The lines almost have the same shape and width. Results: The spectral resolution of SBFTS is presented leave each other in theory and experiment. The results are according to each other. Conclusion: The spectral resolution of SBFTS mainly lies on the maximum optical path difference. The interferogram is referred to as being "auto-apodized" since the off-axis effect and tilt angle of the moving mirror theirself appear to impose an apodization function on the interferogram. The auto-apodization of the interferogram is likely to result in a ILS that is broadened in frequency and reduced in amplitude. In addition, the ILS appears to be shifted in frequency and the side-lobes of the ILS are asymmetric. In the long wave band the spectral resolution of SBFTS only rest with the maximum optical path difference. It is not infected by off axes effect because of using plane array detectors and the small tilt angle of the moving mirror. But in the middle wave band its spectral resolution is debased by the off axes effect.
Optical fiber frequency shift profilometry
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A novel phase demodulation and projector design method for 3D profile measuring is presented. The system employs a LD as a light source and CCD as a detector. LD and small optical fiber space encoding projector is used to make the system tight and convenient. The light is guided into optical fiber by optical fiber coupler. This method is based on two-optical-fiber interference principle. The projector is made up by six single-mode fibers. Six single-mode fibers are ranged closely into right line to form three pairs of coherent light sources. The space length of every pair of optical fibers is different. The ratio of space length is 1:3:5. Three frames of deformed interference pattern with different spatial frequency are produced. The phase can be demodulated through algebraic operation, arc cosine and phase unwrapping of three frames of interferogram. Theoretical model is established for optical 3D measurement. Phase formula and unwrapping method is given. Numerical simulation and experiment results show that this way is feasible.
Three-dimensional profile measurement of steep object by optical fiber frequency mixing fringe projection technology
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Based on the theory of Fourier transformation profilometry(FTP), a novel profile measurement of steep object using fiber frequency mixing projection is proposed. With this method, optical fiber frequency mixing interference fringes are acquired through three optical fibers interference. It is made of three sets fringes with different spatial frequency. The spatial frequency of the interference stripes is changed through changing the spacing of the optical fiber end. The new three- optical- fiber frequency mixing profilometry only needs one frame of image to demodulate phase. Two deforming fringes with different frequency are captured at the same time. The surface range of the object is detected by the low frequency fringes. The precision depends on high frequency fringes. Finally, the exact profile of steep object is detected by data fusion. In the paper, a multi-functional projector is designed. Theory and experiment research are done to verify this novel method. Experimental results show that the method features accurate phase unwrapping with extensive measurement range.
Virtual orthogonal grid method for calibrating structured light binocular vision measurement system
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In order to calibrate structured light depth image object surface profile measurement binocular vision system, a calibration mathematical model and calculation method is given. Special gauge head is fixed on precision automatic platform, and then moved by standard space length in two-dimension measured section. Every orthogonal point's gauge head image is collected by subsystem. All orthogonal point coordinate values form a virtual grid field. The whole measurement section is divided into standard square region. From system coordinate transformation, the orthogonal point coordinate values in subsystem are one-to-one correspondence with real object coordinate values in the binocular vision measurement system. In every standard square region, the real object coordinate values are calculated and calibrated by segment linear interpolation. Detailed calibration algorithm principle and error analysis are given. The results show that a group of orthogonal grid point can calibrate the whole system measurement section. The systematic measurement errors are less than 0.15 mm within 100mm depth measurement range.
Research on optoelectronic image identifying technology of biomolecule encoding
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An innovation way to detect and identify biomolecule encoding is studied and a practical optical-mechanical-electrical integrative sensor system is accomplished, for which, a comprehensive analysis of the spectrum information, grayscale information as well as the location information is conducted. In our system, a LED as a light source, is used to provide a uniform illumination, and a CCD image sensor is used to obtain gray grading information of biomolecule encoding chip. And then, Wavelet analysis technology is used to eliminate noise and smooth the image signals. The location of each encoding dot and its average gray can be realized automatically by means of these methods, the features of the biomolecule encoding can be identified. And all of the characteristics on molecule encoding are displayed on screen in several different ways finally. Compared with NMR and IR technique, our design of the system is small in size, easy to operate and low cost.
Modeling and analysis of the mathematic model of differential astigmatic optical system used for the FPC (flexible printed circuit) online detection system
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The surfaces of flexible printed circuit products are discontinuous, it is imperative to provide a non-contact measurement system to measure not only non-continuous surface, but also surface topography and small dimension. Optical detection system based on differential astigmatic can solve the problem. In the existing literature, the mathematic model of differential astigmatic optical system is established by Geometrical optics, it brings imprecision factors. So it is necessary to establish a precise mathematical model of differential astigmatic. This paper analyzes the shortcomings and inadequate of the mathematic model of differential astigmatic optical system which is based on geometrical optics of traditional optical systems, and then analyzes the model based on laser Gaussian beam model, which is more accurately closer to actual situation. Subsequently, according to the mathematic model, this paper optimizes the optical path parameters and also analyzes the impacts of position errors of optical components upon the measurement, which lays the foundation of the improvement of the online FPC quality control system.
Laboratory radiation calibration experiments of TDI CCD camera
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Radiation calibration is a necessary part in making camera. In fact, the essential of radiometric calibration is not only used in visible light and infrared light. The calibration is also needed in many measurement and exploration process. The essential of calibration accurately is to confirm the relationship of measurement values and physical quantity. The task of radiometric calibration of TDI CCD camera is to make certain the relationship between the input radiance parameters and the output gray values. The radiometric calibration of TDI CCD camera is done in the State Key Laboratory of Applied Optics. An integration sphere is used for simulating different radiance, which is decided by the sun vertex angle and reflectivity of ground. The linearity of TDI CCD response and the relationships between the response and the gain and stage separately are tested. According to test results, we get the parameters including gains and stages, which are sent to the camera. The errors are discussed after the experiments terminate.
Infrared spectra analysis method of multi-component mixed gas concentration based on support vector machine
Wenjun Xie,
Peng Bai,
Lei Xiao
Show abstract
Component concentration analysis of mixed gas is an important part for measurement. In this study a regression model with support vector machine using a data set with 5000 samples is developed and applied to predicting unknown component concentration of mixed gas. Through transformation of kernel function, multidimensional and overlapped spectrum data is mapped into high dimension space, so that regression model of mixed gas is carried out in high dimension space of support vector. Some factors such as unitary process, scan interval, range of wavelength, kernel functions and penalty coefficient C that affect model are discussed. Experimental results show that component concentration maximal error is 1.45%. The difficulties of overlapping feature spectrum, identical method of mixed gas analysis, limit number of training sample and dimension of input spectrum are solved and the model brings important theoretical and applied value.
Measurement of refractive index in optical fiber prefabricated stick with scanning method
Hongying Zhou,
Jiabu Chen,
Qiu Gao
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The refractive index of optical fiber Prefabricated stick has great effect on the transmission characteristic of optical fiber. Consequently, it is necessary to measure the distribution of refractive index. In this paper, a new method is proposed to measure the distribution of refractive index, which uses a thin light beam to scan the optical fiber Prefabricated stick. When a thin light beam irradiates on the optical fiber prefabricated stick, the light is converged because the optical fiber prefabricated stick acts as a columnar lens. After passing by a series of refraction, the light passes through the optical fiber prefabricated stick. Based on the model of refractive index distribution in the optical fiber prefabricated stick, the theoretic output point can be calculated. At the same time, the practical light output point can also be got through experiments. An evaluation function can be constructed with these two values. The model of refractive index distribution in the optical fiber prefabricated stick can be corrected by Monte-Carlo method gradually. At last the evaluation function value will become very little and the practical refractive index distribution can be got.
Design of drivers for tiny LCD reticule image generator used for optical measurement
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Replacing some optical vitreous reticules with digital reticule images generated by high-resolution tiny Liquid Crystal Device (LCD) can avoid repeating operations of installing, adjusting and focusing optical vitreous reticules during optical multi-parameter measurement. In this way, optical multi-parameter measurement's efficiency and precision can be enhanced obviously. For this brainchild, we designed an instrument with hardware by utilizing Field Programmable Gate Array (FPGA). The FPGA's main function is to fulfill a XGA signal driving circuit. This circuit generates 'horizontal synchronization signal', 'field synchronization signal' and 'video signal' which can drive the tiny LCD. At the same time, designing device driver programs such as external SRAM memory under embedded Linux operation system is another most important job in software aspect for the apparatus. This apparatus makes high-resolution and high-capacity digital reticule images displaying on tiny LCD accurately and rapidly. This paper mainly introduces the design method and process of 'standard XGA signals driver circuit' and 'device driver programs under embedded Linux'.
Application of semiconductor laser on big dimension measuring system
Hongtao Zhang,
Xuhua Zhai,
Xun Zhou,
et al.
Show abstract
The structure and principles of an optical non-contact measuring system of large-dimension diameter were analyzed in detail 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 measurement of on-line parameters in processing. The ultimate errors in measuring large-dimension diameter are less than 0.02 millimeters.
Singularity analysis of pavement surface images
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The framework of analyzing the image singularity based on the sub-pixel multifractal measure (SPMM) is presented in this paper. Performing SPMM can give the sub-pixel local distribution of image gradient and a more precise singularity exponent distribution of the image. And the MSM detected this way reflects the most important information of the image. Meantime, using singularity exponents and the most singular manifold, the image can be decomposed into a series of sets with different statistical and physical properties automatically and easily. Using the pavement surface crack image as an example, it shows that the physical and geometrical properties of the structures can be obtained by analyzing the distribution of singularity exponents and the most singularity exponent. Furthermore, the pavement surface images with or without crack can also be distinguished.
Gas cell based on cascaded GRIN lens for optical fiber gas sensor
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Based on the theory of gas molecular absorption spectrum, a transmission type gas cell based on cascaded GRIN lens has been designed. The gas cell is the kernel of the optical fiber gas sensor system. The system performance is relative to rationality of gas cell structure. By using GRIN lens couple in gas cell, we can solve the problems of optical discrete components. We use GRIN lens with pigtail fiber as collimating or focusing lens for transmission type of gas cell. To shorten sensor's size and length, and enhance sensor's sensitivity, we present a method by using cascaded GRIN Lens couples to compose a gas cell. With this method, the optical path length is increased and the detection sensitivity of the gas cell is greatly increased. This transmission type of gas cell based on cascaded GRIN lens couples have been applied to our system of absorption spectrum optical fiber gas sensors. We designed and manufactured a gas cell with cascaded GRIN lens couples. Experimental results show that transmission gas cell based on cascaded GRIN lens couples has a good detecting effect.
Study on high speed dual-frequency laser interferometry in two longitudinal modes
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The frequencies of measuring signal and reference signal output from dual-frequency laser interferometer based on frequency-stabilized double longitudinal modes with thermoregulation are too high to count directly. The signal with right frequency generated by oscillator featuring high frequency stability is used to mix them respectively to get transformed signals with low frequency which can be counted. A fully alternating current system with high measuring speed is gained. This paper presents a schematic diagram of the optical system, a signal processing system of the measuring system and the basic formula for the selection of frequency of the oscillator. The mode interval of developed system is 728MHz, the used counter is 82c54, its top counting frequency is 10 MHz, the frequency of oscillator is determined for 723MHz. Experiment results from a 3m laser length measuring machine with measuring speed better than 1300mm/s, resolution 0.32 μm demonstrated that the system can effectively meet the requirements of high speed measurement and calibration.
Study and application of high accuracy and long size measurement based on machine vision
Li'na Yang,
Yuekang Shan,
Xiancheng Zhang
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The visual inspection technology, which can extraordinarily reduce inspection cost, greatly speed up of development and raise the efficiency of production, has become the topic of the day in industrial online inspection in recent years which is widely used in the field of industrial inspection1. In this paper, a method of high accuracy and long size base on machine vision is developed, and some key techniques are introduced in detail, such as lighting system, optical lens, camera, and image processing algorithm. The quality of image is improved by optical imaging and lighting system. A CMOS (Complementary Metal-Oxide Semiconductor) camera with a selected optical lens was used to capture the image of an object. The analogue signals of the image were transformed into corresponding digital grey level values. By using the binarization technique, the images of background and the object were segmented. The precision of edge detection was improved by sub-pixel technique. The precision of fitting was improved by least square method and Hough transformation. Space coordinate was transformed from an image pixel coordinate through coordination. An automatic detection system of ceramic pieces was also developed. And by taking example of ceramic piece 80 mm long and 80 mm wide, the test method is applied by the detection system with accuracy about 8um.The outcome of experiment accords with the fact, this method is simple and feasible, and is of high accuracy, dependability, and high automation.
Reconstruction of off-axis lensless Fourier transform digital holograms based on angular spectrum theory
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A simple holographic high-resolution imaging system without pre-magnification, which is based on off-axis lensless Fourier transform configuration, has been developed. Experimental investigations are performed on USAF resolution test target. The method based on angular spectrum theory for reconstructing lensless Fourier hologram is given. The reconstructed results of the same hologram at different reconstructing distances are presented for what is to our knowledge the first time. Approximate diffraction limited lateral resolution is achieved. The results show that the angular spectrum method has several advantages over more commonly used Fresnel transform method. Lossless reconstruction can be achieved for any numerical aperture holograms as long as the wave field is calculated at a special reconstructing distance, which is determined by the light wavelength and the chip size and the pixel size of the CCD sensor. This is very important for reconstructing an extremely large numerical aperture hologram. Frequency-domain spectrum filtering can be applied conveniently to remove the disturbance of zero-order. The reconstructed image wave field is accurate so long as the sampling theorem is not violated. The experimental results also demonstrate that for a high quality hologram, special image processing is unnecessary to obtain a high quality image.
Novel measurement for large dimensions based on two-longitudinal mode thermal frequency-stabilized He-Ne laser
Bin Wu,
Wanfu Dong
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This paper presents a novel technology for precisely measuring dimensions of large workpieces. The two-longitudinal thermal frequency-stabilized He-Ne laser is applied as the light source and the beat wavelength for measurement basis. The beat wavelength is between 300mm~500mm and its stability can be 10-7 ~ 10-8. For phase measurement of high frequency signals, the accuracy has been improved by applying sampling frequency mixing, and precision measurement for large dimensions can be achieved.
Novel measurement method for selective laser sintering transient temperature field
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In the course of selective laser sintering (SLS), transient temperature has directly effect on protyping mechanism and quality. According to the analysis of transient temperature, infrared thermograph test method is proposed in this paper. Point and line temperature is measured immediately, and the test result is compared with numerical simulation. The result indicates that the test agrees with theory, and the proposed method provides steady base for selecting sintering parameter reasonable.
Research on the affect of differential-images technique to the resolution of infrared spatial camera
Guang Jin,
Yuan An,
Yingchun Qi,
et al.
Show abstract
The optical system of infrared spatial camera adopts bigger relative aperture and bigger pixel size on focal plane element. These make the system have bulky volume and low resolution. The potential of the optical systems can not be exerted adequately. So, one method for improving resolution of infrared spatial camera based on multi-frame difference-images is introduced in the dissertation. The method uses more than one detectors to acquire several difference images, and then reconstructs a new high-resolution image from these images through the relationship of pixel grey value. The technique of difference-images that uses more than two detectors is researched, and it can improve the resolution 2.5 times in theory. The relationship of pixel grey value between low-resolution difference-images and high-resolution image is found by analyzing the energy of CCD sampling, a general relationship between the enhanced times of the resolution of the detected figure with differential method and the least count of CCD that will be used to detect figure is given. Based on the research of theory, the implementation process of utilizing difference-images technique to improve the resolution of the figure was simulated used Matlab software by taking a personality image as the object, and the software can output the result as an image. The result gotten from the works we have finished proves that the technique is available in high-resolution image reconstruction. The resolution of infrared spatial camera can be improved evidently when holding the size of optical structure or using big size detector by applying for difference image technique. So the technique has a high value in optical remote fields.
Study on phase unwrapping algorithms in interferogram processing
Yongguo Li
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Phase unwrapping problem has raised great interest in last decade because it is encountered in many image signal processing fields. For ideal wrapped phase maps, the unwrapping work is straightforward. In practice, the data obtained includes a high proportion of noise; perhaps speckle noise, electronic noise, and sampling aliasing, and so on. Unwrapping of noisy interferogram still presents a challenge. Filtering work could distort the phase data of the processed map and cause filtering aliasing. In order to use phase unwrapping algorithm with reliable to test and analyze, and simplicity to program and implement. Special request has been analyzed about the elimination of noise in wrapped phase field. A scheme for pre-unwrapping filter is proposed. Noise-reduction were discussed that can filter wrapped phase data without smoothing the edges of phase jumps. It has proved that the pre-unwrapping could strengthen the interference fringe clarity during noise elimination, and it has good retention of original information. The use of this filter allows unwrapping of noisy phase maps with simple and fast Fourier unwrapping algorithms, thus avoiding the need for complex unwrapping routines.
Research on dual-purpose optical aspheric surface testing instrument
Jianchun Liu,
Yinbiao Guo,
Gujin Liu
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Aiming at various influential factors during ultra-precision aspheric surface testing, besides improving the accuracy of moving stage and measuring probe, systematic errors in measurements should be minimized. In this paper, the principle of measuring, configuration and design of a new type dual-purpose optical aspheric testing instrument are introduced. Both contact and non-contact measurement methods are used. The performance and cost of this dual-purpose instrument are better than single purpose instrument.
Interferogram region extrapolation technology by exemplar-based image inpainting
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Fast Fourier Transform (FFT) is one of the most important interferogram analysis methods with the merits of single interferogram captured, low experimental environment requirements and better accuracy. FFT arithmetic can only process numeric discrete data and requires that the number of line and row pixels must be 2 to the power n. But unfortunately, interferograms captured are circular in general. The fringe extrapolation method has been proved to be very effective in avoiding Gibbs phenomenon and reducing phase evaluation errors. Gerchberg proposed a simple iterative algorithm to extrapolate the interferograms, but there is not a good evaluation criterion of the iterative times. In this paper, a method of exemplar-based image inpainting is proposed. First, the priority of each patch on the "fill front" should be calculated. We define its priority P(p) as the product of two terms p(p)=C(p)D(p).C(p) is the confidence term and D(p) is the data term. The patch with the highest priority is obtained. Then, the best exemplar patch corresponding to the patch with the highest priority is discovered in the exemplar region. And the relevant data is copied from the best exemplar patch to the unfilled parts of the patch with the highest priority. Finally, the confidence values of pixels which have been filled just now are updated. The whole region will be fully filled through iterating the above steps. Computer simulation and experiment make it clear that the proposed algorithm extrapolate the texture and structure information effectually.
Experimental assessment on the performance of laser total station measurement system for FAST
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The metrology system to measure position and orientation of the cabin for FAST model consists of three Leica laser total stations. An innovative way was involved to test the performance of the metrology system. Large numbers of experiment data were obtained, including 116 groups of dynamic data and 62 groups of static data. There are many problems to be solved from experiment. 240ms delay time was found and characteristic frequency was detected. The dynamic capability of this metrology system was tested. The metrology system will work in the quasi static in FAST and FAST down scale model.The static position RMS error is less than 0.4mm and orientation RMS error less than 0.08°. Results of the total station examination indicate that this system can meet the requirement of the model. In spite of some dissatisfactory aspects, e.g. sampling rate, the total station will play an important role in the FAST.
Zernike polynomials for evaluation of optical system in use
Baozhong Shan,
Baoping Guo,
Hanben Niu,
et al.
Show abstract
Affected by working condition, performance of optical system will decline, especially for large system or system in bad and complex condition. Integrated analysis can predict its performance through multi-subject engineering analysis. Thermal\structural\optical(TSO) integrated analysis is typical[1]. The key problem in TSO process is data transmission among optical, mechanical and thermal programs. Each item of Zernike polynomials has corresponding meanings with Seidel aberrations and is widely used in project, optical design software and interference checks. It is convenient and mature to use Zernike polynomials as data transmission tool between optical and structural analysis program. In TSO process, the principle, fitting method and fitting process of Zernike polynomials are outlined. This method was successfully used in some optical system's design and fabricates process.
New approaches to fabric fused-fiber M-Z interferometer type interleaver
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The interleaver component, which enables very-high-channel-count Dense Wavelength division multiplexed (DWDM) systems and is widely applied in mux/demux system, is a kind of photon-component without source. One type of them is a fused-fiber Mach-Zehnder interferometer. Because of its all-fiber design, it has very low loss, uniform response over a wide wavelength range, very low dispersion, and minimal polarization-dependence effects. In this paper, we put forward and study a novel approach to fabric an interleaver. The method enables real-time measurement and control, and it obtains more flexibility and reduces the cost in procedure. Analysis and numerical simulation results in the paper have some directive significance for practical fabrication of interleaver.
Digital holography research on paraxial optical system
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Based on the theory of object wave reconstruction by means of inverse calculation of Collins' formula, the equations of object wave reconstruction are put forward in digital holographic research. An example of computer simulation of object wave reconstruction is presented.
Fast image processing on chain board of inverted tooth chain
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Discussed ordinary image processing technology of inverted tooth chain board, including noise reduction, image segmentation, edge detection and contour extraction etc.. Put forward a new kind of sub-pixel arithmetic for edge orientation of circle. The arithmetic first did edge detection to image by Canny arithmetic, so as to enhance primary orientation precision of edge, then calculated gradient direction, and then interpolated gradient image (image that was detected by Sobel arithmetic) along gradient direction, last obtained sub-pixel orientation of edge. Performed two kinds of least-square fitting methods for line edge to getting its sub-pixel orientation, from analysis and experiments, the orientation error of improved least-square linear fitting method was one quarter of ordinary least-square linear fitting error under small difference of orientation time. The sub-pixel orientation of circle made resolution of CCD increase 42 tines, which enhanced greatly orientation precision of image edge. For the need of quick on-line inspection next step, integrated the whole environment containing image preprocess, Hough conversion of line, setting orientation & direction of image, sub-pixel orientation of line and circle, output of calculation result. The whole quick processing course performed without operator, processing tine of single part is less than 0.3 second. The sub-pixel orientation method this paper posed fits precision orientation of image, and integration calculation method ensure requirement of quick inspection, and lays the foundations for on-line precision visual measurement of image.
Aggregate particle image segmentation
W. X. Wang
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The most important and hard part of computer vision for aggregates, is segmentation. Segmentation can be divided into two steps, one is segmentation based on gray levels (called image binarization sometimes) in which a gray level image is processed and converted into a binary image, the other is segmentation based on particle shapes in a binary image, in which overlapping and touching particles will be split, and over-segmented particles will be merged based on some prior knowledge such as shape and size etc. In this paper, according to authors' work experiences, several kinds of aggregate image segmentation algorithms are analyzed and discussed; therefore, the suggestions for aggregate image segmentation are proposed.
Measurement of the micro-displacement of metal bar with ESPI-phaseshift method
Zhu Zheng,
Li Chen,
Zhibing Sun
Show abstract
The technology for the measurement of a micro-displacement with ESPI-Phaseshift method has been introduced in the paper. In order to measure a micro-displacement, the technology gets laser speckle pattern interferometric information (i.e. phase information) from sample object surface in different loads with CCD camera. The phase information will be transformed into displacement information by relevant software. The micro-displacement is measured consequently. The measurement result of a sample metal bar which is fixed on one side and loaded randomly on the other side is presented in the paper. Experimental result matches well with theoretical calculation. The technology presented in the paper has higher precision than that of traditional methods, and the experimental conditions for the technology are easy to achieve.
Design of orienting and aiming instrument based on fiber optic gyroscope
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In order to improve the ground viability of missile weapon system, a quick orienting and aiming instrument is cried for the missile launching in modern war. The fiber optic gyroscope (FOG) based on Sagnac effect is a new type of all solid state rotation rate sensor that detects angular changes or angular rates relative to inertial space, which has many fine characteristics compared with traditional mechanical electronic gyro, such as low cost, light weight, long life, high reliability, wide dynamic range, etc. For the need of missile photoelectric aiming facility, It is necessary to design and manufacture a set of orienting and aiming instrument based on single axis FOG, to solve the close quarters aiming of missile launching, to measure the azimuth reference. Based on practical project, the principle of FOG orienting system and laser collimation theodolite aiming system is discussed and studied in this paper. Orienting and aiming system are constructed in the same basement. The influence of platform tilt on the precision of orientation is analyzed. An accelerator is used to compensate deviation caused by base tilt. The aiming precision affected by eccentricity of the encoders for laser collimation theodolite and the FOG orientation system are analyzed. The test results show that the aiming accuracy is 6' in three minutes. It is suitable for missile aiming in short range.
Effect of coupling effectiveness on fiber optical probe
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A fiber optical probe which is a non-contact, type and highly accurate, and small sized is designed in this paper to detect some holes which are only several millimeters and must be under monitor. Based on Gauss transferring theory, the mode matching principle and matrix optical theory, the effect of the structure of the optical fiber and lens connection is studied. Then the confocal speciality between optical fiber and GRIN lens is also studied based on a fiber optical confocal scanning microscopy (FOCSM). The coupling structure which can get maximal coupling efficiency is designed. Results of preliminary experiments are presented finally.
Feature extraction of fog from multi-spectral infrared images of FY-2C geostationary satellite
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FY-2C is geostationary satellite which is researched and developed by China. The primary advantage of geostationary satellite is the ability to characterize the radiance by obtaining numerous views of a specific earth location at any time of a day. This allows the production of a composite image to monitor short-term weather better. This paper describes a technique that uses multi-spectral infrared composite images of FY-2C to estimate particles emission and recognize fog at night. Radiations of particles detected by FY-2C at different wavelengths are analyzed combined with solar spectral irradiance. Having several spectral bands makes the analysis algorithms more complex and inefficient, thus it is important to choose the most respective bands. By applying Karhunen-Loeve transform to raw data of FY-2C, the infrared images are analyzed. By comparing Eigen image of these infrared images with visible image in the same batch, it is concluded that data of IR3 contribute to the first Eigen image mostly, which shows that the newly added IR3 channel of FY-2C has greatly improved the ability of distinguishing short time weather phenomena. Producing composite images by calculation and analysis at sequential period of time can clearly show changes of fog coverage. The improvement of the geostationary satellite instruments that have come to pass will encourage more widespread use of these derived products in the coming years.
Effective indexes of refraction and limiting properties of ethyl red
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The nonlinear optical properties of ethyl red (ER) doped PMMA film are measured, and the effective indexes of refraction n2 of the film at the three wavelengths are -1.08×10-9, -2.28×10-9 and -1.35×10-10m2W-1 respectively. It indicates that ER sample has a larger optical nonlinearity compared with other optical materials. The nonlinear absorption of ER film at the three wavelengths is measured respectively. The self-diffraction of the film at 441.6nm and at 535nm is investigated respectively, and the results indicate it possesses high quality of optical limiting. The lasers of 441.6nm and 535nm can all induce thermal self-defocusing effects in the film.
Research on errors of half-waveplate and quarter-waveplates in polarized laser interferometer
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Based on Jones matrices theory and polarized phase-shift technology, one of the most important elements of polarized interferometer that is the error source and action mechanism of wave plates is researched. There are two reasons that cause wave plate error, one of which is immanent parameter error and the other one is location error. When environmental temperature changes and vibratory jam exists, the error of different elements will couple, which makes nonlinear error on the polarized interferometer more complex. It opens a door for selecting wave plates, adjusting light set-up and compensating error. In this paper, the point is the experiments on the wave plate error, which is on the base of theory. Every single error on the polarized interferometer is discussed with the isolation of each wave plate, so that the character of nonlinear error will be reached with composite error. In the experiments, difference delay angle error of two 1/4 wave plates is -10 degrees~10 degrees and location angle error is -5 degrees~5 degrees in interferometer. The aim of this paper is to realize the mechanism of nonlinear errors' appearance and the varying rule of nonlinear errors in laser interferometer. The effects of the environmental factors (temperature and oscillation) on the measurement accuracy and the compensation for the environmental changes are also studied. All above provide error remove or compensation for laser interferometer in nanometer level measurement with theoretical foundation and search after application.
Online measurement for surface defects of running wheel set
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Wheel set tread defects include scotching and flaking on wheel tread. The paper presents an online measuring method to detect wheel set defects based on optoelectronic technique while the train is running in low-speed within 5-10km/h. Line structure laser illuminates on the wheel tread. High speed CCD cameras were used to gather tread image. Digital image process technique is used to process the data. The measuring device is installed along the straight railway. When the vehicle is running in a limited speed, the devices placed on both sides of the railway can get depth, length and position of possibly existed wheel defects. The measuring accuracy of defects length was 1.0mm.
Aspheric surface test by digital moire method
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Research is conducted on digital moire method based on partial compensation lens and its application on aspheric surface test Compared with the null compensator method, the partial compensator method for aspheric surface test proposed by the authors has the characteristics of large compensation range, general usage field, and easier to manufacture of the partial compensator lens, it has also lower efficiency and is non intuitionistic used in ordinary interferometer directly. By the use of digital moire method, the interference fringe between virtual standard reference aspheric surface constructed by digital technology can be obtained and real surface can be tested, and then the interference fringe can be analyzed by moire method. In consideration of real-time intuitional display of the aspheric surface error interference fringe is convenient for setting and adjusting the optical system, we also made a real-time moire fringe processing equipment, which composes and filters moire fringe between real interference fringe captured by a 2k×2k CMOS camera and the virtual standard reference fringe by hardware circuit. The moire fringe is showed on a SXGA display, whose frame frequency is up to 10f/s.
Diode laser based continuous-wave cavity ring-down technique for high reflectivity measurement
Show abstract
A continuous-wave cavity ring-down (CRD) technique, in which a diode laser is employed as light source, is developed to determine the high reflectivity of optical dielectric mirrors. Based on on-axis alignment, large resonant peaks are obtained for CRD signal. When the amplitude of signal exceeds the predefined threshold, laser beam is switched off and a single exponential decay signal is obtained to fit the cavity decay time. The reflectivity of the cavity mirror, measured at several cavity lengths, is statistically determined to be 0.99737 at 1064 nm, with an uncertainty of 6×10-5. On the other hand, with off-axis geometry, a steady signal is obtained to make a sensitive lock-in measurement and the steady signal itself fitted with appropriate theories to determine the cavity decay time. The reflection of the cavity mirror obtained by three methods and at different cavity lengths are in excellent agreement.
Laser output power stabilization for circular laser writing systems by using acousto-optic modulator
Show abstract
We present experimental results on the output power stabilization of an Ar+ laser for a direct circular laser writing system (CLWS). Instability of the laser output power in the CLWS causes resolution fluctuations of being fabricated diffractive optical elements or computer-generated holograms. For the purpose of reducing the power fluctuations, we have constituted a feedback loop with an acousto-optic modulator, a photodetector, and a servo controller. Here very important things are proper conception of the servo controller and selection of a proper photodetector depending on what kinds of lasers to be controlled. In this system, we have achieved the stability of ± 0.20 % for 12 minutes and the relative intensity noise level of 2.1 x 10-7 Hz-1/2 at 100 Hz. In addition, we applied our system to a 2 mW internal mirror He-Ne laser. As a consequence, we achieved the output power stability of ± 0.12 % for 25 minutes.
Image segmentation based on bi-stable system
Xiaofei Wang,
Yuli Yan
Show abstract
Image segmentation is one of the most demanding tasks in optical image processing. In this paper, a new algorithm based on a two variable reaction-diffusion equations is proposed. A stable auto-organized pattern can be obtained by choosing suitable control parameters. Several image processes including image binarization, contrast enhancement, edge detection and noise reduction can be achieved Compared with the conventional methods, the new algorithm indicates a higher accuracy and continuity for the image. Moreover, it can preserve the information such as edges during image processing of noise reduction.
Research on key technologies of non-contact measurement system of optical aspheric surface
Gujin Liu,
Yinbiao Guo,
Jianchun Liu
Show abstract
According to the requirement of high precision measurement of optical aspheric surface, 4D measurement platform is
under development. Open motion control system is adapted and multi-axes motion control card is mounted in IPC.
Repeatability accuracy and positioning accuracy of the full travel of the driving unit of the platform can reach to 0.3μm
and 1μm respectively. Laser sensor is droven by the ultrasonic LM (USLM) to the position needed to be tested. The fine
positioning of the unit is achieved by USLM with its DC drive mode, which can perform nanometer steps proportional to
the input voltages. The positioning error of the driving unit can not be prevented. In this paper, the mathematic model of
error compensation of the USLM driving unit is found and software compensation is introduced. Results of
compensation show that the position accuracy of this driving unit is greatly improved and can fulfill the task of optical
aspheric mirror surface measurement.
Study on pattern formation in dielectric barrier discharge by optical method
Show abstract
The spatio-temporal behavior in pattern formation in dielectric barrier discharge system is hard to be studied in the mixed gas of air and argon at high pd product, for the discharge duration of micro-discharge (filament) in streamer mode is very short. In this paper, pattern formation phenomenon in streamer mode in dielectric barrier discharge is studied by optical method. A rich variety of patterns has been observed in streamer discharge mode in the mixed gas of air and argon. It's found that the appearance of these patterns is very sensitive to air concentration and applied voltage. Regular patterns such as hexagon and square structure can be formed in this system when the parameters space is proper. The applied voltage for obtaining the hexagon (or square) pattern increases with increasing air concentration. These regular patterns sometimes drift in a certain direction and sometimes rotate stochastically. The drifting velocity is estimated through dividing the filament trace length by exposure time of the photo. It is found that the drifting velocity increases generally with increasing air concentration and the drifting velocity of hexagon pattern is larger than that of square pattern. The light waveforms from irregular pattern or random walking filaments are un-orderly and stochastic. On the contrary, the light waveforms of regular patterns are very orderly and periodical, only two pulses in each half cycle of the applied voltage. In our experiments, it is also found that the spatial frequency of pattern increases with increasing air concentration.
Study on the diameter and discharge duration of filament in dielectric barrier discharge in air/argon
Show abstract
The spatial-temporal correlation in dielectric barrier discharge is difficult to be studied in the mixed gas of air and argon. In this paper, a simple optical method is introduced to study the temporal correlation intensity between micro-discharge filaments in dielectric barrier discharges at different air concentration in mixed gas of air and argon. The relation of the breakdown voltage and air concentration (Χ) is measured. It's found that the breakdown voltage increases as the air concentration increasing. The experimental results show that the diameter and discharge duration of the filament decrease with the air concentration increasing, at the same time the coherence of the discharge moments of the filaments weakens with the air concentration increasing. The experimental results can be explained with the theory of electron drifting. In addition, the accumulated charges on dielectric surface created by the filament discharge create a field within very time when the duration is small, which against the filament breakdown in its neighboring region. So the coherence of the discharge moments of the filaments can't be realized. While the accumulation of the surface charges will last a long time when the duration of the filament discharge is big, the breakdown can take place in the neighboring region of the filament in the duration, which would be the factor to the coherence of the discharge moments.
Discharge domain in dielectric barrier discharges in air at atmospheric pressure
Show abstract
Lifetime of micro-discharge filaments in dielectric barrier discharge in air at atmospheric pressure is very short and high temporal resolution device is necessary to study time correlation between micro-discharge filaments. In this paper, a simple optical method is introduced to study time correlation between micro-discharge filaments in dielectric barrier discharge in air at atmospheric pressure by photomultiplier tubes. The waveforms of light emission indicate that the discharge burst within each half cycle of applied voltage consists of a series of discharges pulses. This experimental phenomenon shows that the discharges of two or more filaments would overlap in time. By time correlation study, it is found out that discharge filaments can be categorized to some groups according their spatial position. The filaments can volley almost at the same time within neighboring space whose dimension is less than 3x3mm2. A discharge domain is proposed to denote the group of discharge filaments that volley at the same time and exist in a neighboring space. The temporal behavior of filaments belong to one domain is investigated in many applied voltage cycles. The probability distribution function of the intervals for the discharge filaments in a domain is given at last. The delay time between breakdown moments of two filaments in one domain varies within the range of a few ns order. The physical mechanism involved in photo-ionization is presented to interpret the domain formation.
Application of laser bar code technology in power fitting evaluation
Show abstract
In this work, an automatic encoding and management system on power fittings (PFEMS) is developed based on laser bar coding technology. The system can encode power fittings according to their types, structure, dimensions, materials, and technical characteristics. Both the character codes and the laser bar codes of power fittings can be produced from the system. The system can evaluate power fittings and search process-paper automatically. The system analyzes the historical values and technical information of congeneric fittings, and forms formulae of evaluation with recursive analytical method. And then stores the formulae and technical documents into the database for index. Scanning the bar code with a laser bar code reader, accurate evaluation and corresponding process-paper of the fittings can be produced. The software has already been applied in some power stations and worked very well.
Data preprocessing of the exterior field of vision assembling photogrammetric camera
Show abstract
Transmit array photogrammetric camera can obtain image which is high geometric fidelity and high photogrammetric quality. However, the single chip array CCD image sensor camera can't meet the need of measuring precision and photogrammetric covering area. In order to obtain large numbers of information and extensive photogrammetric covering area, we must increase field of vision angle and improve photogrammetric covering area. And all these objects can be realized by exterior field of vision assembling photogrammetric camera. Two side work must be done before images, which obtained by exterior field of vision assembling photogrammetric camera, be used in photogrammetry. First, all assembling camera focal plane need be converted to a benchmark coordinate focal plane to realize camera digital assembling. Second, images must be re-sampled and processing. Because of coordinate conversion, two images from different assembling cameras can be established function relation, which a pixel of image from a camera is corresponding to a pixel of another image from different camera. But through this conversion, some pixels maybe extrusion together and other pixels separate on an image area. So interpolation direction finding(IDF) is used to obtain these pixels and realize image re-sampling. In this paper, the structure of exterior field of vision assembling photogrammetric camera is analyzed, and the coordinate conversion method of exterior field of vision assembling photogrammetric camera and image gray re-sampling method also can be discussed. All the works are based to data pretreatment of exterior vision assembling photogrammetric camera.
Study on the detection sensitivity of APS star tracker
Show abstract
Detection sensitivity is an important parameter of star tracker, which can express detection limit of the weakest detected visual star magnitude. Detection sensitivity of APS star tracker is related to APS parameters, optical system aperture and lens permeance rate, SNR, and so on. This paper, the expressions of APS star detected signal and APS noise are given, so signal-noise ratio (SNR) of star tracker can be obtained. And based on the theory inspecting signal from noise and optimal SNR threshold detection principle, the detection sensitivity model can be obtained. The corresponding APS star tracker detection limit is obtain based on APS IBIS5 and general optical system parameter design. When SNR threshold is 8.1 which can obtain 99.9% detection probability, we can calculate that the detection sensitivity is 6.5 visual magnitude.
Smoothing of optical images using a partial differential equation
Show abstract
Image smoothing is realized by using a FHN (FitzHugh Nagumo) model which is a typical partial differential equation. The model exhibits three characteristics of dynamics: excitable, Turing/Hopf instability, and bistable. In the bistable region diffusion process in space leads to the availability of image smoothing and decides the smoothing effects. After comparing with average filter and median filter it is found that the effects of image smoothing by FHN model are as good as that by other filters. Results show that this approach is effective to image smoothing.
Research on reflecting performance of dopes for laser extinction chamber
Hua Li,
Qianrong Chen,
Liang Feng,
et al.
Show abstract
Double-light-path method with an integral sphere is adopted to obtain the reflectivity indirectly at the wavelength λ=1.06μm for extinction dope on different material samples such as curtain, carpet, the surface of concrete components of the chamber. At laser wavelengths in far IR wavebands, such as CO2 tunable laser with the wavelengths among the range from 9.0μm - 11μm, an improved method is used with a diffuse reflection gold panel with weak absorption and high reflectivity in far IR waveband. By using the blackbody for contrast during test, the sky background for the test environment is utilized. The extinction performance of chamber is checked by sampling different position of the chamber's inner surface. At last, further error analysis, which is intended to reduce the measurement errors in the test procedures and in the test data proceedings, is provided.
Study on the emission spiral patterns by changing the sidewall of the discharge system
Show abstract
In this work, a rich variety of emission spiral patterns have been obtained in dielectric argon/air barrier discharge (DBD) system with a special designed water electrodes setup. We investigate the characteristics of spiral patterns with two kinds of different sidewall materials. By analyzing the image and the light signals of the patterns, it is found that spiral patterns with different sidewall material have different characteristics. The profile of the intensity distribution curve under the glass sidewall appears as a sinusoidal oscillation, while displays in relaxation oscillation mode under plastic sidewall. The space frequency spectrum of spirals under glass sidewall contains only one order spectrum, while the space spectrum of spirals under plastic sidewall contains more than two orders of space frequency spectrum. The experiment results indicate that the sidewall material may affect the excited property of the discharge system.
Argon (2P-1S) spectral lines measurement in dielectric barrier discharge (DBD) by optical emission spectroscopy
Show abstract
The variations of the intensity of argon (2P→1S) spectral lines with various gas mixing ratios in dielectric barrier discharge (DBD) in air/Ar and N2/Ar admixtures are studied. The relative intensity of Ar I I750.39nm/I763.51nm as a function of experiment conditions (pressure, applied voltage and frequency) in Ar discharge is also measured. In air/Ar and N2/Ar admixtures, it is observed that the higher levels of N2 molecules have quenching selectivity for Ar (2P→1S) spectral lines, and the relative intensity of Ar I I750.39nm/I763.51nm increases with increasing air or N2 concentration in two admixtures, respectively. Both Ar (2P→1S)spectral lines and the relative intensity of Ar I I750.39nm/I763.51nm in N2/Ar admixture are higher than that in air/Ar admixture under the same air and N2 concentration in two admixtures. The relative intensity of Ar I I750.39nm/I763.51nm increases from 0.81 to 1.73 when the concentration of air changes from 10% to 73%, but the relative intensity changes from 1.03 to 3.51 when the concentration of N2 increases from 10% to 73% in N2/Ar admixture at a applied voltage of 10kV, a frequency of 26kHz and an atmosphere pressure. Moreover, in Ar discharge, the results demonstrate that the pressure has great effect on the relative intensity of Ar I I750.39nm/I763.51nm, which decreases with increasing the pressure. But it changes slightly with the applied voltage and the frequency.
Method for removing temperature shifting during measurement of large mirrors in grinding process
Show abstract
In order to provide precise feedbacks to manufactures, the effect of temperature shifting must be removed from the measurement results. To remove the effect of temperature shifting to measurement results, large mirrors were measured twice. The first measurement procedure was done fast, often for several points a line. These measured data were set as datum for removing the temperature shifting. The second measurement procedure was done densely, for about 100 points a line. After the abovementioned two measurement procedures, a temperature-shifting-removing program was developed to remove temperature shifting, which fits the densely measured data to the datum data. To verify the validity of this temperature-shifting-removing method, we have made a comparison of the results of a spherical mirror 200mm in diameter measured by this method and the results of the same mirror measured by using Form Talysurf PGI 1240 from Taylor Hobson. Two measurement results show good agreement.
Measurement of optical surfaces with knife edge method
Show abstract
A method that upgrades the knife edge tester from a qualitative tester to a quantitative one was introduced in this paper. Moving the knife edge tester back and forth in the focus of the mirror, the variations at the center of curverture of annuluses of the mirror can be got. Using mathematic method, these variations of the center of curverture can be calculated as the deviations of real surface to perfect surface. An experiment has been done by using the method. The calculated deviations of the optical surface was compared with the results measured by Form Talysurf PGI 1240 from Taylor Hobson. Two-measurement results show resemblance.
Analysis and simulation of an all-fiber polarization transformer
Show abstract
Based on the analysis on the variable coupled-mode equation, we proposed an optimal profile of variably spun rate Q(z) = 0.5tan{arcsin[(z/L)sin(arctan2Q(L)]} to get better performance for all-fiber polarization transformer (AFPT), where Q(z) is normalized spun rate by beat length LB along the fiber length L. Then, in accordance with the intrinsic structure of AFPT, and in consideration of considering the phase-difference effect, we calculated the Jones vector from point to point along fiber to simulate the evolution of state of polarization (SOP) in AFPT with this optimal spun rate profile. For comparison, calculations are also made with other two kinds of spun rate profile (linear, cosine) often used in the AFPT fabricating process. The Influence of spun rate variation profile on the polarization transforming performance of AFPT is discussed and compared in detail. It is found that both in the case of linear-in/circular-out where the extinction ratio of output light is required as small as possible and in the case of circular-out/linear-in where the extinction ratio of output light is required as large as possible, the AFPT with optimal spun-rate profile presents best performance, and the linear spun-rate profile is the worst. The analysis and calculation results have referential values to the design, fabrication and evaluation of AFPT samples.
Research and design of intelligent distributed traffic signal light control system based on CAN bus
Show abstract
Intelligent distributed traffic signal light control system was designed based on technologies of infrared, CAN bus, single chip microprocessor (SCM), etc. The traffic flow signal is processed with the core of SCM AT89C51. At the same time, the SCM controls the CAN bus controller SJA1000/transceiver PCA82C250 to build a CAN bus communication system to transmit data. Moreover, up PC realizes to connect and communicate with SCM through USBCAN chip PDIUSBD12. The distributed traffic signal light control system with three control styles of Vehicle flux, remote and PC is designed. This paper introduces the system composition method and parts of hardware/software design in detail.
Design of video processing and testing system based on DSP and FPGA
Hong Xu,
Jun Lv,
Xi'ai Chen,
et al.
Show abstract
Based on high speed Digital Signal Processor (DSP) and Field Programmable Gate Array (FPGA), a video capture, processing and display system is presented, which is of miniaturization and low power. In this system, a triple buffering scheme was used for the capture and display, so that the application can always get a new buffer without waiting; The Digital Signal Processor has an image process ability and it can be used to test the boundary of workpiece's image. A video graduation technology is used to aim at the position which is about to be tested, also, it can enhance the system's flexibility. The character superposition technology realized by DSP is used to display the test result on the screen in character format. This system can process image information in real time, ensure test precision, and help to enhance product quality and quality management.
Application of SPM interferometry in MEMS vibration measurement
Show abstract
The resonant frequency measurement of cantilever has an important position in MEMS(Micro Electro Mechanical Systems) research. Meanwhile the SPM interferometry is a high-precision optical measurement technique, which can be used in physical quantity measurement of vibration, displacement, surface profile. Hence, in this paper we propose to apply SPM(SPM) interferometry in measuring the vibration of MEMS cantilever and in the experiment the vibration of MEMS cantilever was driven by light source. Then this kind of vibration was measured in nm precision. Finally the relational characteristics of MEMS cantilever vibration under optical excitation can be gotten and the measurement principle is analyzed. This method eliminates the influence on the measuring precision caused by external interference and light intensity change through feedback control loop. Experiment results prove that this measurement method has a good effect.
Image sensor and its application in vibration distribution measurement
Show abstract
Aimed at the research actuality of displacement distribution measurement of each point at the measured object surface in condition of micro-motion, we developed a high-speed image sensor based on low-speed CCD in this paper, which can be used for vibration measurement. The operating principle of the sensor and the collecting principle of synchronization data are analyzed. The sensor combined with sinusoidal phase-modulating (SPM) interferometry was used in vibration distribution measurement. Thus each vibration displacement of the measured object surface was gotten. So the displacement distribution measurement of a low cost, high-speed and high precision was realized.
Research on path planning and data processing system for high-precision aspheric measurement
Jun-jun Ye,
Jiang Guo,
Yin-biao Guo
Show abstract
Three methods for axisymmetric aspheric measuring are put forward and estimated. In accordance with the requirements of high-precision compensation machining and polishing, a data processing system with high accuracy is presented. The monotonous and super-quadric aspheric equations are used to verify the nonlinear least square fitting method respectively. The result of this investigation shows the adopted algorithm can complete the high-precise curve fitting exactly, and it can effectively evaluate the surface quality of optical component.
Design of twin computer-generated holograms used for testing concave conic mirrors
Yi Xie,
Qiang Chen,
Fan Wu
Show abstract
A circular computer-generated hologram (CGH) for testing a concave conic mirror is designed. It consists of two segments, called main CGH and alignment CGH. Main CGH, which is fabricated on the inner part of a flat substrate, used for testing a conic mirror. The outer segment is alignment CGH, used for calibrating the main CGH precisely and eliminating misalignment errors such as tilt, decentre and defocus. Both of them are fabricated on the same substrate. First, the principle and process are reviewed. Then an example designed for measurement of paraboloidal mirror (diameter, 300mm, f number 1.5) is presented. At last the designed data is verified with ZEMAX and the residual error of outgoing wavefront is 0.0018λ (P-V).
High precision sensing system for vibration distribution measurement
Guotian He,
Chaowei Tang,
Lijuan Zhao,
et al.
Show abstract
Aimed at the study actuality of displacement distribution measurement of each point on the surface in the micro- motion status, a new vibration displacement distribution interferometry combining sinusoidal phase-modulating(SPM) with Fourier transform is proposed in the paper, its principle and the influence on the measuring precision caused by noise is analyzed in theory. The corresponding interferometer adopting this technique above mentioned was developed The interferometer can be applied into vibration measurement, and vibration distribution measurement. By measuring a mirror's microvibration, the vibration distribution measurement was realized, its repeatable measuring precision was 5.61nm. Experimental results validated the feasibility of the interferometer.
Novel interferometry for crystal thickness measurement
Lijuan Zhao,
Chaowei Tang,
Guotian He,
et al.
Show abstract
Crystal has been widely used in optical fields. In many instances the thickness of optical axis direction of crystal as an important physical parameter needs to be confirmed, so it is necessary to accurately measure the crystal thickness. In this paper we propose to measure the crystal thickness by using the birefringence characteristics of crystal and analyze the feasibility in theory. Furthermore we validated the realization process of the measuring system and the algorithm of calculating crystal thickness by experiments. The repeatable measuring precision was several nanometers.
SPM interferometer with large range for mirco-vibration measurement
Mingyi Fu,
Chaowei Tang,
Guotian He,
et al.
Show abstract
The measuring range and precision are two inconsistent parameters of traditional optical interferometry. In this paper, the interferometer measuring vibration with high precision and large range is proposed and its measuring principle is analyzed in detail. The interferometer obtains phase information by processing interference signals with two real-time phase discriminator and the vibration displacement could be gotten by expanding this phase. The measuring range was enlarged from half wavelength to millimeter. Meanwhile, the measuring precision was independent of external disturbance and vibration displacement measurement with high precision was realized. The measuring range of vibration displacement for 6000.5nm and the repeatable measuring precision was 5.72nm from experiment. The feasibility of the measuring method was validated by experiments.
Optical constants measurement system for a:H silicon film
Show abstract
A type of optical constants measuring system controlled by a computer was developed. The system consists of a focusing lens, a monochromator that is composed of a diffraction grating and a photomultiplier, a high-precision voltage amplifier, a level buffer circuit, a data-sampling card composed of a A/D converting circuits, a interrupt circuit and I/O interface circuits and a PC. The heart of the system is a PC, which is served as data sampling, processing and calculating unit. The transmission spectrum of α:H silicon film is measured by this system. Then, a kind of envelopes calculation method proposed by Manifacier is used to calculate refractive index, absorptive coefficient and optical band. The accuracy is of the same orders as for the iteration method.
Analysis of array illumination generalized by the combination of a binary phase grating and a lens
Huai-sheng Wang
Show abstract
In this paper we propose a method to use a binary phase and a lens to fulfil array illumination. An equation is given to research the array illumination by a given binary phase grating and a lens. We use a lens with the two main excellences. One is that, the lens can raise the intensity of reflected light from a reflective object. Sometime the reflected light is too weak to be recorded. The other is the spatial structure to be conveniently adjusted by the binary phase grating and the lens. Thus industry measurement relevant to array illumination is more easily carried out.
Application of a single phase array plate for implementing phase-shift of a digital hologram
Huai-sheng Wang,
Ying-jie Yu
Show abstract
A method though the combination of a phase array plate and linear interpolation has been used to substitute phase-shifting, where effect of nonlinear interpolation is neglected. In this paper we mainly study the effect of non-linear interpolation in a phase array plate. The results of reconstructed image under several nonlinear interpolations such as cubic and nearest interpolations are given and are compared with those of linear interpolation and standard interpolation. Because only one hologram is needed in our method, it can be used in real-time measurement of a moving object.
Tracing platform for infrared laser atmospheric communication between warships
Jinghua Sun,
Xiaojun Zhang,
Ming Wang,
et al.
Show abstract
The "infrared laser atmospheric communication between warships" mainly solves the problems of secrecy and real-time communication in modern warfare condition. Concerning infrared laser atmospheric communication, the primary problem we should solve is how to acquire, point, and trace an object (shorted for APT) using the optical systems on warships. Therefore, a suitable platform is necessary. The platform is proposed in this paper, which includes the platform's general design framework and principle, the acquisition and tracing algorithm of optical signals, and technical targets. The algorithm is simple and practical. The design of the platform is practically significant for more research in infrared laser atmospheric communication system.
Online extrinsic parameter calibration of stereo vision coordinate measurement system
Qiaoyu Xu,
Dong Ye,
Rensheng Che,
et al.
Show abstract
To carry out precise measurement of large-scale complex workpieces, accurately calibration of stereo vision coordinate system becomes more and more important. This paper presents a flexible and valid method for calibrating stereo vision coordinate system, which overcomes the complexity and difficulty of traditional calibration methods. By moving the optical reference bar over the measurement volume with known length for three horizontal infrared LEDs and three vertical infrared LEDs as feature points, the relative orientation and position of two cameras can be quickly determined with epipolar constraint of the stereo cameras catching features through linear algorithm and LM iteration method. The scale factor of the translation between two cameras can be calculated by the distance between two extremity feature points of the optical reference bar. By automatically controlling the light intensity and optimizing the exposure time, the feature points can get uniform intensity and obtain higher S/N ratio at different distance, so the calibration accuracy is improved. Experiment result proves that the calibration method proposed is flexible, valid, and can obtain high calibration accuracy and good results in the application.
Compensator design for aspheric testing using virtual glass model
Show abstract
Compensation method is a popular method for testing aspheric surface. In this dissertation, a compensator is designed according to normal aberration compensation method. In order to realize the normals of emergent wavefront of compensator consistent with that of aspheric surface, the concept of virtual glass is adopted. According to the characteristic of aspheric surfaces, general method of determining virtual glass model's parameters in ZEMAX is presented. Single pass layout using virtual glass model for designing compensator is proposed. It reduces the number of surfaces by a half. This simplifies the process of design and optimization and improves the accuracy of design. A design example is given. The maximum optical path difference is less than 0.0001λ(λ=632.8 nm).
Design of a CGH wavefront generator for aspheric testing with wavefront tracing method
Show abstract
Aspheric surfaces are widely used in optical systems. Advanced testing technology is needed for the production of aspheric surfaces. Compensation method is a popular method for testing aspheric surfaces. In order to realize the certification of compensator that is composed of multiple lenses, reflective CGH whose diameter is smaller than that of aspheric surface is used as aspherical simulator to calibrate the compensator. The challenge of realizing the accurate certification of the compensator is of high accuracy design of CGH. According to optical propagation theory, wavefront tracing method is proposed in this dissertation. The derivation process of wavefront tracing method is given. By using this method, the phase function of CGH can be directly acquired. Simulators of many different aspheric surfaces are designed. The design results prove the feasibility of wavefront tracing method. Compared to ray tracing method, the wavefront tracing method can simplify the design process and improve the design accuracy.
Design and application of a set of equipment to test the attenuation performance of aerosol to 10.6um laser emission
Xuanyu Wang
Show abstract
A set of moveable equipments was designed and applied to test the attenuation performance of aerosols to 10.6μm laser emission. The set includes a CY-40 CO2 laser, an aerosol producer, a control device, a cooler, a power detector and an A/D card. The laser can produce not only pulse but 0.5W to 40W continuous laser emission. Moreover, the set can be used not only indoors but also outdoors to test the attenuation performance of various aerosols to 10.6μm laser emission within 50m distance. The principle and method to test the attenuation performance of aerosol with a strong concentration to 10.6μm laser emission in smoke chamber and outdoor field were expounded in detail. The formulas to calculate the transmittance and extinction coefficient of aerosol to laser emission were discussed with an example of oil fog smoke. From outdoor experiment, the average mass extinction of oil fog to 10.6μm laser emission is 0.127m2/g. Experimental results prove that the set of equipments may be widely applied to test and evaluate the transmitting performance of 10.6μm laser emission through different aerosols.
Additional Papers
Design and evaluation of corner compensation patterns for anisotropic etching
Xing Chen,
Dong Weon Lee,
Jong Sung Park
Show abstract
This paper reports corner compensation methods for fabricating the intact mesa structure in MEMS (Micro-Electro-Mechanical System). To investigate the undercutting problem in the mesa structure, over ten corner compensation patterns are designed by computing the relations among a series of parameters, e.g. etching rates in different crystal planes, etching depth, etching times, etc. The compensation patterns are then simulated by the simulation software Anisotropic Crystalline Etch Simulation (ACES) beta 2, the 3D etching simulations are gotten. Various new compensation structures preventing the undercutting of convex corners of (100) silicon in THAH solution are redesigned and optimized based on the simulation results, the fabrication are conducted to verify the feasibility of the corner compensation patterns.
Focal plane location in digital holography
Yan Yang,
Bo-seon Kang,
Yeon-jun Choo
Show abstract
The correlation coefficient method is introduced to locate the focal plane in digital particle holography. It uses the fact that the correlation coefficient is maximum at the focal plane. The factors influencing this method are discussed with a numerical simulation of holograms. For real holograms, the Wiener filter was first proposed to process both recorded holograms and reconstructed images. The application results using the dot array target showed that the Wiener filter is a very effective tool for processing holography-related images. The effects of the dot size and the object distance on the errors in the determination of the focal plane by the correlation coefficient method were investigated by using the calibration target.