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- Front Matter: Volume 7157
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- Poster Session
Front Matter: Volume 7157
Front Matter: Volume 7157
Show abstract
This PDF file contains the front matter associated with SPIE Proceedings Volume 7157, including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.
Session 1
Phase-shifting interferometry using a multi-mode blue laser diode
Show abstract
A phase-shifting interferometry (PSI) using a multi-longitudinal-mode blue laser diode was developed. Since the
longitudinal modes of a laser diode are located almost at even interval and changes synchronously with the injection
current, by setting an optical path difference between two arms of an interferometer in such a way that makes the
contrast of interferogram to be a maximum, the phase shift required for PSI can be obtained by changing the injection
current. Moreover, in such a condition, the PSI system works even mode hops occur. Theory and experimental results for
measuring the transmitted wavefront of an aspheric DVD pickup lens are presented.
A novel acetylene sensing system based on tunable optical filter
Show abstract
A tunable optical filter (TOF) based acetylene sensing system is proposed in this paper. By
modulating the wavelength of TOF within the width of one absorption line of acetylene, both the
sensitivity and selective sensing properties of the system for sensing acetylene have been much
improved. Approximate linear calibration curves in sensing acetylene is obtained by experiments. The
minimum detectable acetylene concentration of 5ppm is also achieved by experiments. The proposed
system has great potential in developing mixed-gas sensing system.
The stabilization of a multiplexed optical fiber interferometer system for on-line precision measurement
Show abstract
The stabilization of a multiplexed optical fiber interferometer system for on-line displacement precision measurement
with a simple electric feedback loop is presented. Based on the characteristics of fiber Bragg gratings, the multiplexed
optical fiber interferometer system includes two independent optical fiber Michelson interferometers of which the optical
path is almost overlapped. One interferometer is used for the stabilization while the other interferometer is used for the
measurement. A feed back signal from the feedback loop is driving a tube PZT on which one arm of the fiber
interferometer is wounded. The phase-shift in the two arms of the interferometer resulting from the temperature
fluctuations and other types of environmental disturbances is compensated. The bandwidth of the feedback loop is 5kHz.
This makes the multiplexed fiber interferometer system stable enough for the on-line precision measurement. An active
phase tracking technique is applied for signal processing to achieve high resolution. The measurement resolution of the
system is less than 2nm.
Current sensor based on giant magnetostrictive material and fiber Bragg grating
Show abstract
A new type of fiber optical current sensor was designed. The sensing head was made by holding a fiber Bragg grating
(FBG) on a giant magnetostrictive material (GMM) rod along the axial direction. The sensing head was put into one of
the air gap of two silicon plate magnetic cores wound by enameled cable. In order to improve the linearity of the sensor,
another silicon plate core with coil was inserted into the other air gap to provide a biased magnetic field for the
Terfenol-D rod. The Terfenol-D rod was elongated in the magnetic field varying with the measured current and the strain
caused the shift of the center wavelength of FBG. In certain biased magnetic field, the relationship between the measured
current and the wavelength shift is linear. Experimental results show that the linear tuning range of FBG is 0.07nm when
the measured current of the winding is 0~3A. The corresponding measurable current of straight conductor is 0~
2313.07A on the assumption that the distance between the axis of the straight conductor and the GMM rod is 10mm.
Application of CdTe/CdS core-shell quantum dots in a DNA fluorescence probe
Show abstract
CdTe/CdS core-shell quantum dots (QDs) with 12 nm in diameters were synthesized in water, and Au nanoparticles
(AuNPs) with 25nm in diameters were prepared by reduction of sodium citrate. Compared with the fluorescent of CdTe
core QDs, the fluorescent of CdTe/CdS core-shell QDs was increased about one times, which suggested the advantage of
CdTe/CdS core-shell QDs in fluorescence application. It was confirmed that the fluorescence emission spectrum of
CdTe/CdS QDs and the UV-Vis absorption spectrum of AuNPs had an obvious overlap, which indicated that a novel
DNA probe based on fluorescence resonance energy transfer (FRET) from CdTe/CdS QDs donors to AuNPs acceptors
could be designed. 3'-SH-DNA were assembled onto the surface of AuNPs by Au-S bond (Au-DNA), and CdTe/CdS
QDs were linked to 5'-NH2-DNA (partly complementary with 3'-SH-DNA) by Schiff's reaction (CdTe/CdS-DNA).
Then, the distance between donors and acceptors of DNA probe was controlled within 1-10 nm by hybridization of
CdTe/CdS-DNA and Au-DNA, which resulted in a FRET from CdTe/CdS QDs to AuNPs according to Forster theory, so
the fluorescent of probe was extremely decreased compared with CdTe/CdS-DNA. The detection ability of this novel
probe was investigated by fluorescence emission spectrum when target DNA (completely complementary with
3'-SH-DNA) existed.
Session 2
Sol-gel coated planar optical sensor for high resolution oxygen measurement
Show abstract
Oxygen detection techniques are essential for marine environment and ecology researches. In this paper, the
development of luminescence intensity-based sensor system for dissolved oxygen (DO) measurement is presented. The
sensor film consists of tris(2,2-bipyridyl)ruthenium(II) (Ru(bpy)3Cl2) as photosensitive indicator which is immobilized
within the mixture of tetraethoxylsiane (TEOS) and methyl triethoxysilane (MTEOS) membrane. The laboratory
experimental results show that the ratio of the fluorescence intensity of the sensor correlates well with DO concentration
from 0 to 32.96 mg/l. Depending on the charge-coupled device (CCD) camera used, the proposed system can monitor the
0.9×0.9 cm areas with 9×9 μm resolutions and it can be used for oxygen distribution measurement in spatial and
temporal scale for undersea monitoring applications.
Development of a wireless crop growth monitor based on optical principle
Show abstract
In order to detect the plant's nitrogen content in real-time, a wireless crop growth monitor is developed. It is made up of
a sensor and a controller. The sensor consists of an optical part and a circuit part. The optical part is made up of 4 optical
channels and 4 photo-detectors. 2 channels receive the sunlight and the other 2 receive the reflected light from the crop
canopy. The intensity of sunlight and the reflected light is measured at the wavebands of 610 nm and 1220 nm
respectively. The circuit part is made up of power supply unit, 4 amplifiers and a wireless module. The controller has
functions such as keyboard input, LCD display, data storage, data upload and so on. Both hardware and software are
introduced in this report. Calibration tests show that the optical part has a high accuracy and the wireless transmission
also has a good performance.
Development of a soil detector based on an optical sensor
Show abstract
An estimation model of the soil organic matter content has been built based on NIR spectroscopy and a portable soil
organic matter detector based on optical sensor is developed. The detector uses a micro processor 89S52 as the Micro
Controller Unit (MCU) and consists of an optical system and a control system. The optical system includes a 850nm
near-infrared lamp-house, a lamp-house driving-circuit, a Y type optical fiber, a probe, and a photoelectric sensor. The
control system includes an amplified circuit, an A/D circuit, a display circuit with LCD, and a storage circuit with USB
interface. Firstly the single waveband optical signal from the near-infrared lamp-house is transferred to the surface of the
target soil via the incidence fibers. Then the reflected optical signal is collected and transferred to photoelectric sensor,
where the optical signal is conveyed to the electrical signal. Subsequently, the obtained electrical signal is processed by
89S52 MCU. Finally, the calculated soil organic matter content is displayed on the LCD and stored in the USB disk. The
calibration experiment using the estimation model of the soil organic matter is conducted. The decision coefficient (R2)
reaches 0.9839 between the measured data by the soil organic matter sensor and by the laboratory chemistry method.
The development of a multi-spectral camera used in the detection of crop growth status
Show abstract
The growth status of crops varies in different parts of any field. Currently, the most frequently used method to measure
the crop growth status is based on the reflectance of visible light and near infra red (NIR), for the reason that using
visible light exclusively is not satisfactory. However, the efficiency of multi-spectral detectors is so low that it has been a
bottle-neck in the application of precision agriculture. Hence, to improve the efficiency of detecting crop growth status is
vital to the development and popularization of precision agriculture. A multi-spectral camera, which is sensitive to NIR,
red and green lights is introduced in this article to solve this problem, with a CMOS device as the imaging unit, an FPGA
as the controlling unit and a CompactFlash card as the storage unit. The FPGA is logically divided into several
independent modules, which are CMOS controlling module, RAM controlling module and MCU controlling module, so
as to implement the function of controlling the whole system. The CMOS controlling module which is functionally the
signal generating module is used to generate the waveforms for the CMOS imaging device and to control the on-chip AD
converter. The RAM controlling module and CF card controlling module are respectively used to control the storage of
the digital data into RAM and into CompactFlash card. Moreover, this paper includes the design of the hardware and
the configuration of the CMOS device which is used to optimize the results of the pictures taken. At last, the work to be
done to optimize the camera is introduced.
Investigation of semi-insulating gallium arsenide photoconductive photodetectors
Show abstract
The structure and working mechanism of a photoconductive photodetector are compared with a p+-i-n+ (PIN) photodiode
and a metal-semiconductor-metal (MSM) photodetector which is regarded as two back-to-back Schottky barrier
photodiodes. Because a photoconductive photodetector has the features of high critical field strength, especially no
junction capacitance and no dead zone, it has the main merits of high signal-noise ratio, ultrafast response and high
quantum efficiency. We fabricate two photoconductive photodetectors in a lateral configuration on a semi-insulating (SI)
gallium arsenide (GaAs) wafer, which wavelength range of response is from UV to 1.73μm due to two-photon
absorption. It is shown by the volt-ampere characteristics curve that the dark leakage current of 30μm-gap SI GaAs
photoconductive photodetector at a bias field of 66 V/cm is less than 1.2 μA. Our experiment has demonstrated that SI
GaAs photoconductive photodetectors are noteworthily superior to high-speed Si PIN photodetectors to measure
ultrashort pulse lasers with the properties of ultrafast response, ultrawide spectral range, high signal-noise ratio and ease
of fabrication.
Session 3
Closed-loop fiber optic current sensor using ferromagnetic collector and Bi4Ge3O12 crystal
Show abstract
Bi4Ge3O12 magneto-optic crystal was chosen as sensitive materials, and a current sensor based on Faraday rotation of
materials was designed. A ferromagnetic collector with an air gap and feedback windings were utilized in the sensor to
construct a closed-loop current sensor. The magneto-optic crystal showed stronger magneto-optic effect and smaller
temperature coefficient when it was exposed to the light, which was produced by a semiconductor laser with a working
wavelength of 655nm. The ferromagnetic collector was used to collect the magnetic field generated by the measured
current. The collector could greatly reduce the influence of the position variation of the conductor on the output. The
measurement system was a closed-loop system due to introducing the negative feedback coil to the measuring system, so
the linear range, linearity, temperature stability and dynamic characteristic index of the sensor were improved greatly.
The principle of this sensor was introduced in detail. The structure of this sensitive component, as well as the signal
conditioning circuit, was given. Some experimental data and the interpretation of these data were presented.
The simulation of electrostatic coupling intra-body communication based on finite-element models
Show abstract
Intra-body Body Communication (IBC) is a communication technology in which human body is used as a signal
transmission medium. Due to its unique characters, IBC technology is proposed as a novel and promising technology for
personal area network (PAN), computer network access, implant biomedical monitoring, human energy transmission,
etc. In this paper, investigation has been done in the computer simulation of the electrostatic coupling IBC by using the
developed finite-element models, in which (1) the incidence and reflection of electronic signal in the upper arm model
were analyzed by using the theory of electromagnetic wave, (2) the finite-element models of electrostatic coupling IBC
were developed by using the electromagnetic analysis package of ANSYS software, (3) the signal attenuation of
electrostatic coupling IBC were simulated under the conditions of different signal frequency, electrodes direction,
electrodes size and transmission distance. Finally, some important conclusions are deduced on the basis of simulation
results.
Endmember extraction by pure pixel index algorithm from hyperspectral image
Show abstract
We describe and validate an automated methodology based on PPI to extract endmembers from images and distinct the
according endmembers. Four main steps are:1)project the raw image cube to its most spectral dimensions and non-noise
components by minimum noise fraction (MNF) technology; 2) use the set of spectrally distinct pixels produced by MNF
as skewers for PPI, generates a list of candidates from which final endmembers can be selected; 3) an automatic selection
procedure based on K-means clustering is consequently performed to determined the centriod of endmenbers. 4) linear
spectral mixing model (LSMM) is used to estimate mixing coefficient. And root mean square error (RMSE) reflects the
accuracy of decomposition. We use the methodology to investigate the unique properties of hyperspectral data and how
spectral information can be used to identify mineralogy with the Airborne Visible/infrared imaging Spectrometer
(AVIRIS) hyperspectral data from Cuprite, Nevada.
Session 4
Design and test of multimode interference based optical fiber temperature sensors
Enbang Li
Show abstract
Fiber-optic temperature sensors offer unique advantages, such as immunity to electromagnetic interferences, stability,
repeatability, durability against harsh environments, high sensitivity and resolution, and fast response. Therefore, optical
fiber sensors have been widely adopted and applied in various areas for temperature measurements. It has been
demonstrated that by using multimode interferences in a segment of multimode fiber, wavelength-encoded fiber optic
temperature sensing can be achieved. The advantages of this kind of temperature sensors include the extremely simple
structure and the ability for high-temperature measurements. In this work, we investigate the interference of core mode
and cladding modes in double cladding fibers. Analysis and simulations are carried out in order to identify the optimal
parameters of the temperature sensor. Practical design of the multimode interference based optical fiber temperature
sensors is investigated, and sensing probes are fabricated and tested. The design details, temperature measurement
experiments, and test results are presented in this paper.
Space-resolved fluorescence spectroscopic measurements with an optical fiber probe
Enbang Li,
Hialin Qiu
Show abstract
By monitoring of the emitted signal from a sample while varying the excitation wavelength, emission wavelength or both
of them, fluorescence spectroscopy has become a powerful diagnostic technology. Fluorescence spectrometers can be
used to measure and record the fluorescence spectra of a given sample, and have been successfully applied in different
areas including biology, biochemistry, chemistry, medicine, environmental science, material science, food industry, and
pharmaceutical industry. In order to increase the flexibility and applicability of conventional fluorescence spectrometers,
we design an optic fiber probe for conducting the UV/Vis excitation light to a sample under study, and for collecting the
fluorescence produced by the sample. Different excitation/emission fiber bundle arrangements have been fabricated and
their performances have been evaluated and compared. Fiber adaptors which can be used for different commercial
fluorescence spectrometers are also developed. In order to achieve space-resolved fluorescence spectroscopic
measurements, we connect the fiber probe to a microscope which is mounted on a 3D traverse stage. Experiments and
measurement results using the space-resolved fiber optic fluorescence spectrometer are presented in this paper.
A wavelength encoded optical fiber sensor based on multimode interference in a coreless silica fiber
Show abstract
A wavelength encoded optical fiber sensor using a three-segmented fiber structure is proposed. The device consists of a
coreless silica fiber (CSF) which is coated with a thin film and spliced between two standard single-mode fibers (SMFs),
forming a SMF-CSF-SMF (SCS) structure. When light is transmitted from the SMF into the CSF, the LP01 mode in the
SMF is coupled to the LP0n modes, and a multimode interference occurs in the CSF. These modes interact with the thin
film, hence the thickness and refractive index of the thin film can affect the modal interference. We analyze the
transmission spectra of the SCS structure to obtain the characteristics of the sensor including sensing sensitivity.
Numerical simulations are carried out by using the Beam Propagation Method (BPM) to investigate the multimode
interference in the SCS. Two different conditions are considered in our studies: 1) changing the refractive index of a
fixed-thickness film, and 2) varying the film thickness with certain refractive index. It has been found that the
wavelength corresponding to the minimum output power increases 0.33509 nm when the refractive index changes every
0.01 from 1.33 up to 1.40, and 6.760 nm when the thickness enhances form 0 to 1000 nm. The trend of the raise is
mostly linear for the former simulation, but gets slower and slower for the latter. The SCS structure can serve as a fiber
platform for non-labeling bio-sensing when a bio-film is coated to the CSF.
Wavelet-based adaptive regularization deconvolution for turbulence-degraded image
Show abstract
The observed object images are seriously blurred because of the influence of atmospheric turbulence. The deconvolution
is required for object reconstruction from turbulence degraded images. The wavelet transform provides a multiresolution
approach to image analysis and processing. We consider a wavelet-based adaptive edge-preserving
regularization deconvolution (WbARD) scheme for image restoration problems. This is accomplished by first casting the
classical image restoration problem into the wavelet domain. We consider the behavior of the blur operator in the atrous
wavelet domain. Then, we are able to adapt quite easily to scale-varying and orientation-varying features in the image
while simultaneously retaining the edge preservation properties of the regularization. Experimental results show that the
WbARD algorithm produces good performance in comparison to standard direct restoration approaches for turbulencedegraded
images.
Session 5
Wavelength tuning of fiber Bragg grating based on fiber side polishing
Show abstract
Side polished fiber Bragg grating (SPFBG) is made as a side of cladding of a FBG is polished just to remain several
micrometers by the a side polishing method, such as a method with a motor-driven polishing wheel. The response of
Bragg wavelength of SPFBG to the refractive index of material overlaid on the polished area of SPFBG was investigated
by both theoretical calculation and experiments. Both calculation and experiments showed that the Bragg wavelength of
side polished FBG would shift to the longer as the refractive index of the overlaid material increased. The sensitivity of
SPFBG to the refractive index of material overlaid on the side polished area could be used for wavelength tuning of FBG
or as refractive index sensor.
Theoretical analysis of D-type optical fiber sensor with a bimetallic layer
Show abstract
In this paper, we consider a SPR sensor based on D-type optical fiber with bimetallic combination. In pursuit of both
higher sensitivity and larger operating range, firstly, we separately analyze the influence of parameters such as the length
of coating L, the incident angle θ and the thickness of Au-coating layer d. when the optimum parameters of sensor are
determined, we analyze the performance of the sensor with different bimetallic combination consist of Au, Ag, Cu and
Al. Lastly, we can get a conclusion that the sensor with L=5mm,d=25nm, θ=88° and Au-Ag at x=0.8 can provide the
best performance in terms of the sensitivity and operating range.
Demodulation of Fabry-Perot pressure sensors based on radial basis function network
Show abstract
In this paper, we present a demodulation of Fabry-Perot pressure sensor method based on radial basis function
network(RBF). RBF network is a kind of three layers frontal feedback neural network with single connotative layer. It is
proved that RBF is able to approach random continuous function with random precision. The cavity length variation is
simulated from 473 to 483 µm with the step of 0.5 µm and the simulation result shows that the relative error of this new
method is less than 0.02% and the maximum absolute error is less than 0.1 µm. The MEMS Fabry-Perot pressure sensor
is also demodulated by the experiment. In the experiment, we change the pressure from 0 to 2 MPa with the step of 0.1
MPa. The experimental result shows that its linearity of the cavity length versus pressure achieves 0.98858 and the
standard deviation between measured pressures and real pressures is less than 0.05 Mpa. By the experiment we can see
that, this RBF network method can obtain upper precision and can reach the practice demand. This new method adapts to
the practice demand with its higher resolution and less calculation time.
Design and evaluation of optical image sensing device for marine plankton monitoring
Show abstract
Marine plankton play an important role in ocean web structure and global environment change. As an alternative to
traditional sampling methods, real time imaging systems are particularly useful in studying the abundance and behavior
of plankton in the appropriate spatial and temporal scales at high sampling rate. In this paper, the design of a noninvasive,
high resolution, low power consumption optical imaging device is presented. The device is designed in a
compact size and this makes it suitable to be deployed on underwater vehicle platforms for plankton monitoring. The
reported imaging system is a balanced compromise of object distance, focal length of the lens, and the coverage of the
sampling area. The results of laboratory evaluation of the combination of different parameters of the optical lens for
plankton monitoring are presented. Light illumination based on light emitting diode (LED) is investigated. It is showed
that the system is capable of obtaining relatively good resolution images at high sampling rate that allow quantification
of the plankton in the appropriate spatial and temporal scales.
Session 6
Temperature-effect measurement of Fresnel reflection by polarization optical time domain reflectometry (POTDR)
Show abstract
We propose a POTDR setup and investigate the Rayleigh scatter and Fresnel refection. A piezoelectric polarization
controller (PPC) is applied in this setup. Based on the transfer matrix theory of the PPC, the state of polarization (SOP)
of the Fresnel reflection is analyzed under different temperature. In the experiment, we find that when any part of the
fiber is affected by the temperature, the SOP of Fresnel reflection will be changed.
A novel method to measure 3D displacement by single camera
Show abstract
This article is to introduce a newly developed method to measure three-dimensional displacement by only a single
camera. To measure the 3-D displacement of the two objects A and B, two lighting diodes are fixed on object A. A
convex and a translucent screen are fixed on object B, a CCD camera is joined together with the screen. The lighting
diodes project two faculae on the screen throgh the lens. The position of the faculae can be detected by the CCD camera.
The 3-D displacement of A and B can be calculated according to the position of faculae.
Optical system for proximity operations in aerospace
Show abstract
Satellite serving offers a potential for extending the life of satellites and reducing launching and operating costs.
Proximity operations are necessary for purpose of satellite serving. As the primary measurement system, optical system
can provide the information of relative navigation in near field.
The paper has two main contributions. Firstly, we summarize use of optical systems for guidance and navigation in the
missions of proximity operations in aerospace. Their characteristics vary from the manned missions, which are
performed by astronauts on-orbit, through semi-autonomous missions, wherein human operators on the ground segment
issue high level directives and sensor-guided systems on the space segment guide the execution, to the full-autonomous
missions, which are executed using unmanned space robotic systems. It comes to light that future space operations will
be more autonomous.
Secondly, we present a concept and framework of a vision system for satellite proximity operations, which is
semi-autonomous and can treat with uncooperative satellites. The vision system uses visible and infrared sensors
synchronously to acquire images, which solves the problem of data integrity introduced by ambient illumination and
direct sunlight for visible sensor. The vision system uses natural features on the satellite surfaces instead of artificial
markers for its operation, computes relative motion and structure of the target, and tracks features in image sequences.
Selected algorithms of the system have been characterized in ground environment; they are undergoing systematic sets of
adaptation for space.
The ultrafast photoconductive characteristics of GaAs bulk investigated by optical-pump terahertz probe spectroscopy
Show abstract
The ultrafast photoconductive characteristics of GaAs bulk were investigated by the optical-pump terahertz-probe
spectroscopy (OPTP) at room temperature. In our experiment, a significant decrease of the terahertz transmittance has
been observed when the time delay between the optical pump pulse and the terahertz probe pulse was adjusted. It can be
concluded that the electronic states of the GaAs became metallic, when the optical excitation occurred on the surface of
the GaAs material. Since we expect only the free carrier response in the terahertz range, the decrease of the transmittance
is obviously assigned to the appearance of the high electronic conductivity due to the increasing free carriers.
Furthermore, it was found that transmittance of the terahertz radiation decreased with the increase of the optical pump
power due to the more optical generated carriers under the higher power. We can also find that the carrier recombination
time of the GaAs became shorter while the power of the optical pump was lowered.
Microsensors based on planar microtoroid cavities
Show abstract
Planar Microtoroid cavities with ultrahigh quality factor have very strong confined function to the electromagnetic wave
coupled into them due to their novel ring-like structures. Therefore, they have very good applications in high sensitivity
sensors and other micro optics components. In this paper, the Planar Microtoroid cavity and its coupling system
constructed together with the tapered fiber are introduced. Then, micro sensors based on the above coupling system are
designed. These sensors measure environmental parameters by means of monitoring the changes in the transmission
spectrum of the high finesse Planar Microtoroid cavities, obtaining fine resolution and high accuracy due to their
ultrahigh quality factor (Q) performance. The sensitive mechanism and the feasibility are demonstrated through optical
and mechanical software simulation. With software BeamPROP, the evident resonance and strengthened phenomenon to
the electromagnetic wave coupled into the micro-cavity are shown, which have a big relation with the light frequency.
The results indicate that, Planar Microtoroid cavity is very promising in designing new micro sensors.
Poster Session
Adaptive optics based on linear phase retrieval technique: numerical simulation and experimental demonstration
Show abstract
Phase retrieval technique is one of the most important methods to measure the wavefront in adaptive optics. In this paper,
a linear phase retrieval (LPR) technique used in close-loop adaptive optics (AO) is introduced. The performance of a
close-loop AO system based on the LPR sensor is researched using numerical simulations first. Then an AO
experimental system based on LPR sensor is set up with a 32-element piezoelectric deformable mirror (DM). The static
phase aberration correction experiment is carried out to research the valid range of phase aberration that can be corrected
and the dynamic characteristic. Both the numerical simulation results and the experimental results show that the LPR
technique can be used in adaptive optics to correct the small phase aberration successfully. The dynamic characteristic
shows that the LPR sensor may be used in real-time AO system in future.
The comparison of CCD and CMOS image sensors
Show abstract
The architectures of CCD and CMOS image sensors are introduced briefly, followed by comparison of their
performances in detail. At last, the future development trends of CCD and CMOS image sensors are prospected. It is
pointed out that CCD and CMOS image sensors will remain complementary and competition, and flourish the image
sensor market together in predictable future.
An FBG-based optical microphone with temperature insensitivity
Show abstract
A fiber optical microphone with temperature insensitivity is described in this paper. A sensor system achieves acoustic
vibration signal by attaching a Fiber Bragg Grating (FBG) to a diaphragm which can response to acoustic vibrations.
Broadband light is launched into the FBG through a coupler and the light reflected by the FBG is directed to another
matched FBG which works as a wavelength demodulator. Vibration of the diaphragm causes stress changes to the FBG,
and introduces variations of the FBG wavelength. Therefore, acoustic vibrations can be detected by measuring the FBG
wavelength variations. In this study, a pair of matched FBGs is employed for both wavelength demodulation and
temperature compensation. These features not only make the fiber optical microphone achieve a stable operation, but
also improve the entire frequency range of demodulation. Compared with traditional microphones, the fiber optical
microphone can achieve low noise and a superior performance of anti-electromagnetic interference.
Strain of optic-fiber/giant magnetostrictive film structure in magnetic field by finite element analysis
Show abstract
The magnetostrictive transducer is the most important part of the optic-fiber magnetic field sensor, and the
optic-fiber/giant magnetostrictive(GMS) film coupled structure is a novel coupling form of the magnetostrictive
transducer. Always we analyze the coupled structure based on the entire coupled structure being sputtered GMS material
without tail-fibers. In practical application, the coupled structure has tail-fibers without films at two ends. When the
entire coupled structure is immersed in the detected magnetic field, the detected magnetic field causes the GMS film
strain then causing optic-fiber strain. This strain transmission process is different from it in the coupled structure entirely
with GMS films without tail-fibers. The strain transmission relationship can be calculated theoretically in the coupled
structure without tail-fibers, but it's complicated to theoretically calculate the strain transmission relationship in the
coupled structure with tail-fibers. After large numbers of calculations and analyses by ANSYS software, we figure out
some relationships of the two strain transmission processes in the respective structures and the stress distribution in the
tail-fibers. These results are helpful to the practical application of the optic-fiber/ GMS film coupled structure.
Novel FBG temperature sensor eliminating lateral strain cross-sensitivity
Show abstract
The novel FBG temperature sensor eliminating lateral strain cross-sensitivity was present and theoretically analyzed. The
temperature sensor characteristic of the FBG based on the method for eliminating lateral strain was researched from
room temperature to 190°C, and the FBG was pressed by lateral force during rising temperature. The lateral force
resulted in the birefringence of the FBG, and the FBG exited two different reflective spectra meeting with the Bragg
condition. The change spacing of the peak value between two reflective spectra is used to eliminate lateral strain crosssensitivity
to temperature, and amend the temperature sensitivity coefficient and the change temperature value.
Measuring FBG's Bragg wavelength using fiber Fabry-Perot tunable filter
Show abstract
A method using fiber Fabry-Perot tunable filter to achieve FBG sensor's Bragg wavelength is described. The system has
the capability to interrogate large number of DFB sensors, whilst obtaining absolute Bragg wavelength with pm
resolution. A demonstration system with 4 strain sensors is presented, which obtains DFB sensor's absolute strain value
and achieves sub-microstrain resolution at 300Hz interrogating rate.
Design of time-resolved fluorometer based on immunochromatography
Show abstract
This paper introduces the design of a novel time-resolved fluorometer based on immunochromatograghy. Different from
the other time-resolved fluorometers, it tests the immunochromatographic strip which is labeled with lanthanide ions and
their chelates. This instrument can provide a rapid, quantitative measurement of analytes present in samples without any
washing steps and it can be used to carry out point-of-care test (POCT). The immunochromatograghy-based timeresolved
fluorometer is composed of a specific optical sensor, a scanning stage, a signal processing system and a
computer control system. The light from UV LED is focused on the test strip by a condense lens group in the optical
sensor. If the labels are present in samples, the fluorescence at 613nm will be exited (when Eu3+chelate is used for
marking substance). After a delay of some microseconds, the fluorescence will be collected by the optical sensor and
converted into electronic signal by a photomultiplier tube (PMT). The concentration of the sample can be calculated
through the standard working curve of this instrument. By testing, the sensitivity is several ng/ml level (when Eu3+chelate is used for marking substance), test linear range is from several ng/ml to 103 ng/ml, in which correlation
coefficient is 99.97%.
A dispersion sensor using whispering gallery modes in a cylindrical micro-cavity
Show abstract
Whispering gallery modes (WGM) in a cylindrical micro-cavity of a silica optical fiber are excited with a tapered fiber
of ~7μm in diameter by evanescence field, and the WGM spectra of the cylindrical micro-cavity with different
diameters (300μm, 400μm and 500μm) are measured. The resonant positions and their separations of the spectra are
assigned precisely by an asymptotic formula. Considering the fiber dispersion and the errors induced from it, the values
of the resonant position and its separation achieved from assignment within the experimental spectra range (1290~1320 nm)
match well with a theoretical calculation and a measured accuracy of the refractive index of the micro-cavity can be
as high as 10-5, which indicates that a dispersion sensor can be formed by measuring the dispersive features of WGM in a
cylindrical micro-cavity.
Toxoplasma gondii DNA detection with a magnetic molecular beacon probe
Show abstract
Toxoplasma Gondii infection is widespread in humans worldwide and reported infection rates range from 3%-70%,
depending on the populations or geographic areas, and it has been recognized as a potential food safety hazard in our
daily life. A magnetic molecular beacon probe (mMBP), based on theory of fluorescence resonance energy transfer
(FRET), was currently reported to detect Toxoplasma Gondii DNA. Nano-sized Fe3O4 were primarily prepared by coprecipitation
method in aqueous phase with NaOH as precipitator, and was used as magnetic core. The qualified coreshell
magnetic quantum dots (mQDs), i.e. CdTe(symbol)Fe3O4, were then achieved by layer-by-layer method when mol ratio of
Fe3O4/CdTe is 1/3, pH at 6.0, 30 °C, and reactant solution was refluxed for 30 min, the size of mQDs were determined to
be 12-15 nm via transmission electron microscopy (TEM). Over 70% overlap between emission spectrum of mQDs and
absorbance spectrum of BHQ-2 was observed, this result suggests the synthesized mQDs and BHQ-2 can be utilized as
energy donor and energy acceptor, respectively. The sensing probe was fabricated and a stem-loop Toxoplasma Gondii
DNA oligonucleotide was labeled with mQDs at the 5' end and BHQ-2 at 3' end, respectively. Target Toxoplasma gondii
DNA was detected under conditions of 37 °C, hybridization for 2h, at pH8.0 in Tris-HCl buffer. About 30% recovery of
fluorescence intensity was observed via fluorescence spectrum (FS) after the Toxoplasma gondii DNA was added, which
suggested that the Toxoplasma Gondii DNA was successfully detected. Specificity investigation of the mMBP indicated
that relative low recovery of fluorescence intensity was obtained when the target DNA with one-base pair mismatch was
added, this result indicated the high specificity of the sensing probe. Our research simultaneously indicated that mMBP
can be conveniently separated from the unhybridized stem-loop DNA and target DNA, which will be meaningful in
DNA sensing and purification process.
Study on detection sensitivity of EMCCD star tracker
Show abstract
Star tracker is a high precise, high reliable attitude measurement component of spacecrafts, which plays
a very important role in attitude measurement and control system. Unfortunately, in low light level, in
order to obtain good quality image, the common CCD needs more time to integral light. This leads low
data output and update slowly. In this paper, the star tracker based on a novel electronic multiply CCD
(EMCCD) is introduced. EMCCD has very high sensitivity. The application of EMCCD is very finite
in space explore field, although it has been applied by some country. At first, the detection sensitivity
of EMCCD is analyzed, based on the signal detection theory in noise and optimal SNR threshold
detection principle, and the detection sensitivity model is established. And then, the main noise sources
of EMCCD are analyzed. Finally, as an example, a specific detection sensitivity calculation of EMCCD
star tracker is provided with given optical parameters and exposure time.
An LPG sensing system for leak detection of oil storage tanks
Show abstract
In order to detect the liquid leak, many researchers present different methods. However, traditional detection methods are
electrical methods, which are costly and unsafe. In this study, we present a LPG sensing system for leak detection of oil
storage tanks. Since LPG is sensitive to external refractive index changes LPGs can be used as sensors to detect oil leak.
Eco-environment quality evaluation based on remote sensing over Qingjiang, Hubei Province
Show abstract
The vegetation eco-environment is one of the import constituent elements for the human eco-environment. This article
assesses the vegetation ecol-environment quality(VEQ) over part of the Qingjiang region by using TM remote sensing
image and principal component analysis (PCA) method. There are various geographical and ecological features having
effect on eco-environment of Qingjiang region, Hubei province. The paper gives an evaluation index system of VEQ by
analyzing regional geographical and ecological features, which are composed of 5 factors on vegetation cover, topography & geomorphology, moisture, land cover and hydrothermal regime. These factors are extracted from the
TM remote sensed data. The PCA method is used to calculate the weight of every index. Based on these indices, an
integrated evaluation model of eco-environment quality is built. With the model, the study region is evaluated and
divided into five VEQ evaluation classified ranks. It is concluded that the VEQ in our study region is good as a whole
and the leading VEQ rank is II and III have occupied the proportion of 76.09%.
Gain characteristics of erbium doped fiber amplifier
Show abstract
In the design of Erbium Doped Fiber Amplifier (EDFA), improving flat-gain has great important significance. The
working principle and gain characteristics of EDFA are introduced briefly, the influence of the factors such as Erbium doped
fiber (EDF) length and pump power on the gain of EDFA is analyzed in detail, and the simulation experiments
were carried out with Optisystem software. The result shows that, when pump power is constant, with EDF length
departing the optimal value, the gain of each channel decreases at different degrees; when EDF length is constant, with
pump power departing the optimal value, the gain of each channel changes at different degrees. Moreover, Er3+
concentration has significant effect on the gain, and there is an optimal Er3+ concentration to get the largest gain.
Subpixel centroiding algorithm for EMCCD star tracker
Show abstract
Star tracker is the most precision attitude measurement instrument of spacecrafts, which plays a very important role in
attitude measurement and control system. The technology of star tracker based on CCD is very popular. Unfortunately,
with a CCD system, a single integration period for the entire sensor is necessitated. This leads low data output and
update slowly. Moreover, CCD star tracker is not proper to micro-spacecraft because its volume, weight and energy
consume cannot further decrease. Thus, the novel electron-multiplying CCD (EMCCD) is starting their way in space
applications field. Centroiding algorithm is a subpixel position determination method proper to star position calculation
because of its high accuracy and simplicity. But its position accuracy is affected by various kinds of noise. In this paper,
the subpixel position accuracy of centroiding algorithm is analyzed. The focus is on the estimation of the attainable
accuracy in the application of EMCCD detector, and analysis of the EMCCD noise influence on the star subpixel
position accuracy to find the methods of improving it. The analysis shows that the main contributors to the errors of
subpixel position come from dark noise, read noise and photon shot noise. Simulation experiment results show that the
subpixel position accuracy can attain 1/45 pixel, which
Research of surface plasma resonance optical fiber hydrogen sensor
Show abstract
An optical fiber hydrogen sensor based on the measuring principle of surface plasma resonance is introduced. The
structure of the hydrogen-sensitive head which is coated with Pd-Ag alloy film on the surface of the etched optical fiber
is investigated theoretically. When hydrogen gas is absorbed into the Pd thin layer of the sensing head, the Pd hydride is
formed and then the refraction index of the etched optical fiber surface will be changed with different hydrogen gas
concentration. The surface plasma wave is stimulated by the light wave in optical fiber and the surface plasma resonance
occurs between the thin metal layer and the medium surface of hydrogen gas. The Pd-Ag alloy film thickness versus the
sensitivity of hydrogen sensing head is analyzed and optimized via the numerical method. The sensing head which is
based on surface plasma resonance is manufactured and used in the experiment system of hydrogen gas detecting, and
the experiment results demonstrate that the detecting system has high sensitivity with the hydrogen concentration in the
range of 0%-4%, the accuracy, resolution and response time are respectively 5%, 0.1% and 30s. This sensor structure can
be applied to detecting the low concentration of hydrogen gas.
Design of electrode for thermo-optic variable optical attenuator based on side polished fiber
Show abstract
Base on the heat transfer theory, the thermal models of thermooptic variable optical attenuator based on side-polished
fiber surrounded by thermooptic polymer with electrode inside were built. The finite element method has been used to
compute and analyze thermal distributions of the thermooptic models. The thermal distributions of both the models with
single stick electrode or helical electrode were analyzed in three directions. According to the analysis, the helical
electrode is a suitable electrode structure for thermooptic variable optical attenuator based on side-polished fiber.
A tracking technology of feature point's fuzzy clustering algorithm based on image stabilization
Show abstract
Object tracking technology combined with image stabilization is called tracking technology based on image
stabilization. Moving objects affect stabilization compensation in tracking algorithm based on image stabilization. The
middle value method, former background method and dynamic clustering method are not useful for rotate or non-rigid
objects. Fuzzy Clustering of feature points is proposed to solve these problems. First background and objectives
membership value of the pixel are calculated, and then pixels are classified to background and target categories
accurately by defining membership threshold of the background and targets. Experimental results show that fuzzy
clustering algorithm resolves the moving target interference problem in image sequence and realizes steady tracking of
object. It is proved to be more robust and less sensitive to the numbers of initial clustering.
Correspondence of feature points on moving object in tracking system based on stabilization
Show abstract
Camera systems are often unsteady on platform of airborne, car borne and ship borne. Stabilization algorithm can
be used to eliminate impact of vibration. But image sequence after processing is different from original sequence. If
there is a moving target in camera field, feature points on the target must be indentified and made sure corresponding
relationship in processed sequence. To solve the problem that moving target features position and correspondence are
difficult to identify in image sequence after image stabilization processing, background updating difference moving target
detection algorithm based on motion analysis is proposed. It uses subsample mean and subsample variance and introduces
the concept of background gray probability to identify feature points of moving target in the steady image sequence. In
addition, to solve the problem of incomplete motion track of feature points caused by obstruction or weak target detection
algorithm, partial limit incomplete smooth track algorithm is proposed. It is used to identify correspondence of feature
points on the moving target, and to solve temporary occlusion of moving object. Experimental results show that moving
target features position and correspondence can be identified quickly through the two algorithms. Single-frame processing
speed can reach an average of 27 ms with DSP6416 processor. Image stabilization algorithm and the two algorithms can be
combined to realize real-time tracking based on image stabilization.
Characteristics of frequency noise in a fiber laser sensor array
Show abstract
A wavelength division multiplexed linear fiber laser sensor array system using four distributed feedback fiber lasers
(DFB FLs)is reported. The characteristics of frequency noise are investigated experimentally. Results show the
interaction between neighboring (in wavelength space) fiber lasers spaced ~2.4nm is so weak that the influence of
crosstalk could be omitted. With optimization of pump sequence, all the fiber laser sensors would reach the system
minimum detectable frequency noise. A further discussion about the influence of transmission fiber is also included.
The key technology and research progress of CMOS image sensor
Show abstract
Since the 1990s, with the development of technology of VLSI, CMOS image sensors have been developed increasingly.
The architecture and working principle of CMOS image sensors are introduced. The main advantages of CMOS image
sensors with respect to CCD are analyzed. The key technical problems of CMOS image sensor are discussed, and the
related solving ways are given. The research status of CMOS image sensors is reviewed. At last, the development trends
of CMOS image sensor are prospected.
A high-stability single-pumped L-band superfluorescent fiber source for the fiber optic gyroscope
Show abstract
In this paper, a simple single-backward configuration with a section of un-pump fiber is presented to achieve a stable
L-band superfluorescent fiber source (SFS). The effects of the structural parameters on the output characteristics of the
L-band SFS in terms of output spectrum, mean wavelength, and linewidth are theoretically examined. By selecting
suitable structure parameters, an L-band SFS with mean wavelength insensitive to pump power is achieved under a
pump power of 190mW, corresponding to a mean wavelength of 1583.20nm, an output power of 47mW, and a spectral
linewidth of 49.6nm. The proposed L-band SFS design shows its tremendous advantages as simple structure and good
performances that make it be useful in WDM system, fiber optic gyroscopes and fiber sensor systems applications.
Analysis on the signal crosstalk of TeO2 acousto-optic tunable filters used in optical communication
Show abstract
As an optical sensor and controller in wavelength division multiplexing (WDM) system, the acousto-optic tunable filter
(AOTF) is one of powerfully several potential sensing candidates. The AOTF can easily achieve dynamically to add/
drop arbitrary wavelength by changing the RF frequency in its range of working wavelength. In this paper, the reason of
the signal crosstalk is given and its characteristic of sidelobe is firstly analyzed on the momentum matching condition.
The coupling equations with multiple acoustic waves traveling simultaneously are presented. The analytic solution of the
diffraction efficiency for the two acoustic frequencies is given, and its impact on the device performances is discussed.
The result is correspondence with experimental results. In addition, because the TeO2 AOTF has a specific structure
based on its design principal, it is shown whether the sidelobes on the diffractive efficiency curve appear is mainly
decided by the bandwidth of the AOTF and the mismatching factors. For a definite device bandwidth, if the total
momentum mismatch is lower than a definite value, the device has no sidelobe. Then, the feasibility of the TeO2 AOTF
as an OADM in WDM system has superiority on signal crosstalk.
Design and realization of label-free optical immunosensor based on porous silicon microcavities
Show abstract
We report the experimental demonstration of a novel label-free optical immunosensor based on porous silicon
microcavity for the detection of Hydroxysafflor yellow A (HYSA). HYSA antibodies were immobilized into the porous
silicon using standard amino-silane and glutaraldehyde chemistry. We monitor the shift of the resonance dip in the
reflectance spectrum when HYSA-BSA is attached to the porous silicon microcavity. The label-free immunosensor is
simple and exhibit excellent sensitivity for HYSA antibodies with a sensitivity of 0.91nm/ng.
The study on sensing of MIG welding pool surface based on structured light
Show abstract
The method with sensing of MIG welding pool surface is studied in this paper.The distributing of arc action
spectrum, pool reflecting action spectrum and pool radiating action spectrum are analyzed. The radiation is weaker at
interzone 500-700nm. So, the structured light source is confirmed to semiconductor laser at wavelength 650nm. Narrow
band filter and neutral density filter are mounted on CCD, they are good for restrained the influence of arc. The pool
width is studied on small current by experimented, deforming and distributing of structured light are confirmed. The
form and sort of splash are studied, the method of reducing and protecting splash are also studied. Welding current is
selected properly to restrained splash. Incident angle of structured light is 30 degree. The MIG pool image is captured by
CCD. Deformed structured light fringes are reflected the information of the concave or convex of the pool.
Detection of air pollutant NO2 and the measurement of sound velocity by laser-induced photoacoustic technique
Show abstract
The PA absorption property of NO2 is tentatively surveyed under the condition of room temperature. Laser radiation of
438.0nm is used as excitation source. It is shown that owing to the enhancement of V-T transfer energy with buffer gas
pressure, the intensity of the PA signal increases when the pressure of NO2 maintains at 665Pa and the pressure of the
buffer gas is increased. But the PA signal is almost invariable when the buffer gas pressure is more than 3×104Pa. The
quantity of NO2 is changeless are responsible for this phenomena. The PA signal shows itself as linearity variation with
NO2 concentration. Trace concentrations of NO2 are detected under ambient conditions. The detection limit of 6.4ppm is
obtained on the basis of SNR=1 with the homemade apparatus. But one can expect much lower value of the detection
limit of this method by improving the detection setup. The velocity of the sound in NO2 gas is measured from the PA
signal. It is about 270m/s. It also finds that the sound velocity varies slightly with the buffer gas pressure.
Two-flash method using red and green lasers in a velocity measuring system
Show abstract
In order to acquire sequence images in PIV measurement system of continuous clashing flow of water, two laser flashers,
the red one and the green one, are used in PIV measurement system. After the digital camera is triggered, the two
flashers flash in a short interval during the exposure period. The red light and the green light illuminate the same region
so that the image records the movements of tracing particles in two colors. Using digital image process technology, two
images, the red one and the green one, can be obtained from the original image. Based on the two images, the flow field
parameters can be calculated. The method possesses predominant advantages: high speed field can be measured using an
ordinary camera and the two images have determinate time labels, so the moving direction of the particles can be
determined easily. The main steps of the method include the transition from Bayer matrix to RGB matrix, the
pretreatment of the images, the analyzation of the velocity and the arrangement of the results.
A spectroscopy-based detector to monitor tomato growth condition in greenhouse
Show abstract
A spectroscopy-based detector is developed to measure the nitrogen and chlorophyll content of tomato leaves and then to
predict the growth condition of tomato plants in greenhouse. The detector uses two wavebands, 527 nm and 762 nm,
since it is proved that these wavebands are sensitive to nitrogen and chlorophyll content in plant leaves by previous field
test. The detector contains: A Y-type optic fiber, two silicon photocells, a signal processing unit, and a MCU. Light
reflection from tomato leaves is transmitted by the Y-type optic fiber to the surface of the silicon photo cells, which
transfer optical signal into electrical signal. Then the analog signal is amplified to conform to the TTL level signal
standard and finally converted to digital signal by MAX186. After that, the MCU carries on a series of actions, including
data calculating, displaying and storage. Using the measured data, the Normalized Difference Vegetation Index (NDVI)
is calculated to estimate the nitrogen and chlorophyll content in plant leaves. The result is directly displayed on an LCD
screen. Users have an option in saving data, either into a USB-memory stick or into a database over the PC serial port.
The detector is portable, inexpensive, and convenient, which make it meet farmers' need in China. The performance test
shows that the growth model works very well, and the device has high accuracy in predicting the growth condition of
tomato plants in greenhouse.
A new method based on morphologic filter and ant colony algorithm to enhance centroid detection accuracy of Shack-Hartmann wavefront sensor
Show abstract
Shack-Hartmann wavefront sensor (SHWFS) is widely used in adaptive optics systems. Its centroid detecting error is one
of the main error sources in adaptive optical systems. There are many factors affecting the detecting accuracy such as
photon shot noise, readout noise, background level of CCD camera and number of detecting pixels. It is very effective to
enhance the centroid accuracy by setting the threshold for the images of the SHWFS. But in daytime, the sky background
is strong and changes very fast. The threshold cannot be chosen automatically either. In this paper, a new method based
on the morphologic filter and ant colony algorithm is proposed to improve the SHWFS centroid detecting accuracy. The
principle of the morphologic filter and the ant colony algorithm is introduced and the simulation results are also
presented. The results show the proposed method can enhance SHWFS centroid accuracy very well.
Single-ended long period fiber grating refractive index sensor based on metal-coated surface plasma resonance
Show abstract
A novel single-ended reflecting long period fiber grating (LPFG) sensor with thin metal film overlay and the sensing
system is described. An all-fiber reflection based surface plasma resonance (SPR) LPFG sensor with three-layer structure
(core, cladding and metal) is established experimentally and fabricated with a pulsed CO2 laser writing system and
vacuum evaporation coating system. Different nm-thick thin metal films are deposited on the reflected LPFG sensor for
the excitation of surface plasma waves (SPWs) and the characteristics of the reflection resonance spectra of the LPFG
sensor for measuring refractive index of fluids are studied. It is found that different thicknesses of different metal films
show different measuring sensitivity. Through the comparison of the resonance wavelength obtained in air, water,
alcohol, glycerin and their mixture solution, different sensitivities of the reflected SPR-LPFG sensor have been achieved.
The proposed SPR-LPFG sensing scheme offers an efficient platform for achieving high performance fiber sensors for
the measurement of ambient refractive index.
Development of a grain volumetric flow sensor based on photoelectrical principle
Show abstract
Field information acquisition plays an important part in Precision Agriculture System. Spatial and temporal variation of
grain yield in a field is important field information. It can guide farmers in a reasonable means of production in order to
save input and improve efficiency. Thus a grain yield monitor is developed based on photoelectrical sensor. The monitor
consists of a LED, a photoelectrical transducer, cables, signal processing circuit, acquisition circuit, etc. The LED and
the photoelectrical transducer are equipped in the left and right sides of the clean grain elevator of the combine harvester,
respectively. When harvested wheat is threshed, clean grain is lifted to the grain tank by the lifting plates of the elevator,
and the grain in a plate will switch off the light from the LED to the transducer. The height of the grain in a plate has a
high correlation with the switching off time of the transducer. To measure the switching off time makes it possible to
estimate grain yield. The signal processing circuit and acquisition circuit are used to monitor whether the light from the
LED is switched off and then to measure the switching off time. And the yield can be calculated from the measured time
based on a calibration model. The performance test shows the developed grain yield monitor is practical.
Degenerate four-wave mixing measurement in iodine vapor
Show abstract
Degenerate four-wave mixing (DFWM) is a nonlinear optical process that has been developed as a
detective tool for making quantitative measurements of gas dynamic properties in the various environments.
This technique can be used to measure temperature and species concentration in both flames and plasma
environments. The resulting coherent signal beam makes DFWM particularly attractive for luminous and
harsh environments, compared to incoherent techniques, such as laser-induced fluorescence (LIF). Forward
DFWM with self-stability of spilt-beam system has been demonstrated in iodine vapor. It's found that there
exists no LIF because of collision quenching at atmospheric pressure and room temperature. But observed
vivid DFWM spectroscopy (554-556nm) of iodine vapor at 0oC and room temperature. Furthermore,
DFWM can probe non-fluorescing species. We describe a novel advanced sensor method for measuring
temperature of gas flows using DFWM. This technique without suffering of severe quenching problems at
atmospheric pressure is of importance to trace atom, molecular and radical in combustion diagnosis.
Theoretical and experimental study of a multi-channel acousto-optic device
Show abstract
A set of coupled mode equations for a multi-channel array acousto-optic interaction is put forward, and its solutions
are derived. The principal diffraction and inter-modulation of multi-channel acoustic waves and their effects on diffracted
light beams are analyzed. The multi-channel array Bragg acousto-optic device is made. The experimental results indicate
that the multi-channel acousto-optic modulators can modulate the light beam of every channel simultaneously.
Experimental investigation of top lighting and side lighting solar light pipes under sunny conditions in winter in Beijing
Show abstract
Natural light is very important element in the quality of vision. Solar light pipes are effective method to induce
sunlight into the room need to be illuminated especially for corridor, some places natural sunlight cannot arrive. Solar
light pipes are also effective ways to reduce electricity consumption for lighting; it can transmit sunlight from outdoor to
the room without generating excessive heat. The performance of two top lighting solar light pipes and one side lighting
solar light pipe were investigated at the same time under sunny conditions in winter in Beijing. The results showed that
side lighting solar light pipes have better performance than that of top lighting one. Side lighting light pipe has better
performance than top lighting light pipe if there are no shelters around the top dome under sunny conditions in winter in
Beijing. Solar altitude is the main reason to give an effect on the performance of light pipes. The experimental results
also showed that top lighting solar light pipes with "snow type" diffuser has better performance compare with the
"diamond type" one. Solar azimuth can also affect the illuminance for whole day to all solar light pipes. So if the
sunlight collector can following with the sun, this problem can be resolved, that is, automatic sun trackers are needed,
but the cost will become too much at the same time. Different regions and different seasons had to select different types
of solar light pipes to achieve maximum output of illuminance in the room. Design of the solar light pipes must adjust
measures to local conditions. Solar light pipes will be popularized in the near future in China because have many
advantages to improve energy efficiency in buildings.
Multiply phase-shifted Fizeau interferometric sensor with a tunable laser diode
Sayaka Idoi,
Hayato Fujita,
Masayuki Kagawa,
et al.
Show abstract
With a newly-developed 16-sample wavelength-shifting algorithm, Fizeau phase-shifting interferometry with a laser
diode (LD) suppresses alignment errors in a test plate. This phase-shifting algorithm includes the elimination of phase
errors due to changes in laser power by LD currents. The measurement phase errors on a 16-sample phase-extraction
algorithm are numerically and experimentally estimated. The surface-profile measurement of a plane-parallel plate is
experimentally shown free from systematic errors.
Generation of fractal speckle using computer-generated holograms and its application to speckle correlometry
Show abstract
When a diffuser is illuminated by the coherent light with intensity distributions obeying a negative power law, speckle fields with fractal properties are produced. Such a random field is called fractal speckles. Fractal speckles have extremely long spatial correlation functions of the intensity distributions in comparison with ordinary speckles. It implies that fractal speckles may extend measurement ranges in various metrological applications based on the spatial correlation of speckles. We report the generation of fractal speckles using computer-generated holograms based on the method of stationary phase and the iterative Fourier transform algorithm, and its application to speckle correlometry is discussed.
Detection of toxoplasma gondii with a DNA molecular beacon probe
Show abstract
Toxoplasma gondii is a microscopic parasite that may infect humans, so there is an increasing concern on the early
detection of latent Toxoplasma gondii infection in recent years. We currently report a rapid and sensitive method for
Toxoplasma gondii based on molecular beacon (MB) probe. The probe based on fluorescence resonance energy transfer
(FRET) with a stem-loop DNA oligonucleotide was labeled with CdTe/ZnS quantum dots (energy donor) at 5' end and
BHQ-2 (energy acceptor) at 3' end, respectively. The probe was synthesized in PBS buffer at pH 8.2, room temperature
for 24 h. Then target DNA was injected under the condition of 37°C, hybridization for 2 h, in Tris-HCl buffer. The data
from fluorescence spectrum (FS) showed that ca 65% of emitted fluorescence was quenched, and about 50% recovery of
fluorescence intensity was observed after adding target DNA, which indicated that the target DNA was successfully
detected by MB probe. The detecting limitation was determined as ca 5 nM. Moreover, specificity of the probe was
investigated by adding target DNA with one-base-pair mismatch, the low fluorescence recovery indicated the high
specificity. The results showed that the current sensing probe will be a useful and convenient tool in Toxoplasma gondii
early detection.