This PDF file contains the front matter associated with SPIE Proceedings Volume 6829, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

The photorefractive effect of ferroelectric liquid crystals (FLCs) with the application of an alternating electric field was investigated. The consecutive rotationally switching motion of FLC molecules under an alternating electric field was modulated by the photoinduced additional electric field at the interference fringe. This spatially periodic difference in the molecular motions of an FLC was confirmed to operate as a diffraction grating.

A LOS solar blind UV communication channel model is presented in the paper, which consists of three sections: propagation loss section, scattering transmission section and background noise section. LOS transmission loss model of UV channel is deduced by Lambert law and noise power calculation is also analyzed. Base on them, a practicable calculation method of signal to noise ratio (SNR) is presented, which is a bridge between system parameters and system performances such as BER and limit communication distance in analysis of UV communication. Transmission loss and SNR of LOS are measured in outdoor experiments. The experiment shows that SNR calculation data agree with the experimental results quite well. The calculation also shows that the limit communication distance of LOS can achieve 7kms with the UV sensor at present.

Sinusoidal wavelength-scanning (SWS) interferometry is unique in that a time-varying interference signal contains phase-modulation amplitude Zb due to the SWS besides a conventional phase &agr;. A rough value of an optical path difference (OPD) longer than a wavelength is obtained from the amplitude Zb, which is useful for shape measurements of rough surfaces. By combing the two values of Zb and &agr;, an OPD longer than a wavelength can be measured with a high accuracy of the order of nanometer, which is useful for shape measurements of optical surfaces. As light sources of SWS interferometers a tunable laser diode with an external cavity is used and a superluminescent diode (SLD) is used with an acousto-optic tunable filter. A shape of a metal surface, a step shape of an optical surface, and a thin-film shape of optical surfaces are measured.

We develop a laser-diode (LD) interferometer for depth profiling. Interference signals are produced by the reflections from the reference mirror and the distributed objects. Four-step current modulation into the LD produces phase shifts with four steps that have a value proportional to the distance from the reference mirror image to the reflection cite and the modulation amplitude. The value of phase shift is gradually increased by changing the amplitude of current modulation. The locations of the reflection cite are measured from the modulation amplitude when the value of phase shifts is suited to π/2.

A phase-shifting Sagnac interferometer that uses wavelength tunability of the laser diode is proposed. A Sagnac interferometer itself is robust for the mechanical disturbances because it has a common path configuration and requires no special reference. Unbalanced optical path introduced between p- and s-polarized beams enables us to implement easy phase-shift by the direct current modulation. Several experimental results indicate that the proposed system is useful for the disturbance-free precise measurement.

A multi-period fringe-projection interferometry with back-propagation method is described to measure surface profiles of a glass plate. Phase distribution of the multi-period fringe formed by interfering the two calumniated laser beams is utilized to determine the position of the two surfaces of the glass plate. The multiple optical fields of the different fringe periods on the two surfaces, which are obtained from the sinusoidal phase-modulated interference signals, are back-propagated to a position where all of the phases of the multiple optical fields become zero. At the same time, the amplitude of the sum of the multiple back-propagated fields becomes maximum. The distances of the back-propagation provide the positions of the two surfaces of the glass plate. In the experiment a glass plates of 2mm-thickness is measured with a precision of 2.3&mgr;m.

A white light interferometer is designed to measure the distributed polarization coupling (DPC) in polarization-maintaining fiber (PMF). By using a Michelson interferometer to compensate the optical path difference induced by the modal birefringence of PMF, both the coupling strength and position of the coupling point can be acquired. The two reflective mirrors on the fixed and scanning arms should be vertical to each other. But in practice, the movable reflective mirror can't be vertically aligned exactly to the fixed mirror, which would lead to angle misalignment. The angle misalignment would induce the variance of the optical path difference (OPD), which would reduce the fringe visibility. Finally, the angle error would lead to a decrease on the signal noise ratio (SNR) and miscalculation of the polarization coupling intensity. The angle misalignment and diameter of the incident light beam both have an effect on the fringe visibility. The simulation results show that the requirement of angle error becomes stricter with the increasing of the light beam diameter. To decrease the angle misalignment, the two plane reflective mirrors should be replaced with the corner cube prisms. A revised coupling strength calculation equation was proposed to minimize the influence of angle misalignment.

In order to overcome the irradiance responsivity calibration troubles caused by the weak response of most spectral radiometers in ultraviolet band and poor ratio of signal to noise, and to meet special calibration condition for some remote sensing spectroradiometers in space, a spectral irradiance responsivity calibration unit based on parallel light illumination mode is established, it is composed of a 150W deuterium lamp and a spherical mirror. The calibration unit gets the output standard value of spectral irradiance by irradiance transfer, this way avoids the spectral reflectance measurement difficulty of the spherical mirror. A flight spectral radiometer model used for space remote sense was calibrated in range from 160nm to 300nm, the calibration error of spectral irradiance responsivity is 4.7%. Some factors which contribute to calibration uncertainties are discussed.

The spatial resolution of a conventional imaging LADAR system is constrained by the diffraction limit of the telescope aperture. The purpose of this work is to investigate Synthetic Aperture Imaging LADAR (SAIL), which employs aperture synthesis with coherent laser radar to overcome the diffraction limit and achieve fine-resolution, long range, two-dimensional imaging with modest aperture diameters. Because of many advantages, LADAR based on synthetic aperture theory is becoming research hotspot and practicality. Synthetic Aperture LADAR (SAL) technology satisfies the critical need for reliable, long-range battlefield awareness. An image that takes radar tens of seconds to produce can be produced in a few thousands of a second at optical frequencies. While radar waves respond to macroscopic features such as corners, edges, and facets, laser waves interact with microscopic surface characteristics, which results in imagery that appears more familiar and is more easily interpreted. SAL could provide high resolution optical/infrared imaging. In the present paper we have tried to answer three questions: (1) the process of collecting the samples over the large "synthetic" aperture; (2) differences between SAR and SAL; (3) the key techniques for SAL system. The principle and progress of SAL are introduced and a typical SAL system is described. Beam stabilization, chirp laser, and heterodyne detection, which are among the most challenging aspects of SAL, are discussed in detail.

The precision circle target sub-pixel centroid location is one of the key factors of large space 3D coordinates measurement. In this paper, the circle retro-reflective targets and optical targets used in large space 3D coordinates measurement are analyzed, and the characteristics and applied fields of target sub-pixel centroid location algorithms such as gray weighted and squared gray weighted centroid location algorithms which combine with bi-linear interpolation or improved cubic convolution interpolation method, are discussed. The influencing factors and improving methods for circle target location are also analyzed. These factors include the resolution of the CCD camera, image grab noise, the size of targets, the choice of exposure time and threshold value, the noncoincidence of centroid and center of the ellipse imaging targets, the distortion influence of deformational targets and so on. Based on these, proper compensating measures are brought out for the problems such as target choice and location, influencing factors and eliminating measures.

The precision of target sub-pixel centroid location directly affects the result of large scale vision 3D coordinates measurement. This paper deeply studies the sub-pixel centroid location algorithm of retro-reflective targets and infrared optical targets used in 3D coordinates measurement system, and makes use of improved cubic convolution interpolation algorithm to increase the number of effective pixels used in centroid location, then gives optimizing adjustment parameters for different types of targets and combined with squared gray weighted centroid location algorithm, finally realizes accurate target sub-pixel centroid location. This algorithm is proved to be effective and robust by simulations and experiments.

Printed circuit board film is used for making PCB. Size and defects are important parameters in PCB films' quality evaluation. An online measuring method based on linear CCD for 500mm width PCB film was proposed. The method included (1) definition of parameters, (2) imaging range, which was wider than a PCB film unit to reduce the errors coming from the assembling of CCD and (3) the 2D scanning of PCB film and CCD. Template matching was used for extracting the interested region. Region growing was used for pinhole detection. Image subtraction was used in breakage detection. And region segmentation was used for size measurement. According to the design and analysis, the online measuring method can meet the demands. Experiments showed that (1) the method can detect and classify PCB films' defects efficiently, and (2) the size measuring accuracy can reach 0.1mm.

In this article, ZnO thin films were deposited on different substrates, including glass, p-Si (100) and n-Si (111) by radio frequency (RF) magnetron sputtering technique. By changing substrate temperature and sputtering power, the influence of the sputtering rate was studied on structural properties of ZnO films. The film structural properties of the crystal phase, the surface morphology and the thickness were characterized by D/MAX-2200 XRD, JEOL JSM-6700F ESEM and AMBIOS XP-2 step meter respectively. The results showed that the films deposited on p-Si (100) substrates were preferred c-axis orientations, and their surfaces were smooth and compact when the substrate temperature was 300 Centigrade degrees.

The precise interferometric systems employed in today's artificial satellites require semiconductor lasers of the highest callibur. But, one particularly large obstacle has stood in the way of their broad application; the stabilization of their oscillation frequencies. While a number of different approaches have been tested, none have provided overall, long-term stability. Most recently, we used a Doppler-free absorption line of Rb atoms with a precision temperature controller and an improved laser mount; in this instance, relative optical frequency stability rated 9.07x10^-13≤&sgr;(2,&tgr;)≤7.54x10^-10, in averaging time for 0.01s≤&tgr;≤23s. By introducing optical feedback, which narrows the laser's linewidth, we obtained improved frequency stability.

In the optical rotary joints, the Dove Prism is employed to rotate an image about the optical axis and compensate optical path of optical signals so that the optical signals can be transferred across the rotating interface. However, manufacturing errors and assembling errors of Dove Prism will affect the coupling efficiency of Dove Prism. In this paper, the analytical expressions for errors of the rotating coupling efficiency are presented when the prism is manufactured with errors in its base angle and pyramidal angle. The analytical result showed that the coupling losses that arise from manufacturing errors would increase as the base angles deviate from the traditional value of 45° and the pyramidal angle increase. At the same time, the influence of assembling errors on coupling efficiency is also analyzed using the method of light ray tracing. The assembling errors of Dove Prism included angular tilt misalignment, height misalignment, and inclining misalignment. The results indicated that these misalignments cause the coupling efficiency of Dove Prism decreased. The coupling efficiency is more sensitive to the height misalignment and angular tilt misalignment than the inclining misalignment.

A scanned Talbot interferometer based on shifting phase mask and fiber is developed to change the inscribed Bragg wavelength. In the scanned Talbot interferometer with scan translation platform and fiber translation platform, the ±1 order diffraction light beams form the interference fringe in the far field, thereinto, the fiber translation platform drives the fiber exposing in the interference fringe, and the scan translation platform causes the fiber shifting in the interference fringe to point-by-point write grating in the fiber. Followed the size of interference fringe is decreases from 10 mm to about fraction of a mm, the coherence length of light beams is reduced distinctly. It is important that the length of mirror could be reduced to the size of interference fringe. Additionally, the pulse energy of light source is also reduced evidently.

Distributed stress sensor with a scanning Michelson white light interferometer can be used to detect stress distribution and its value by analyzing polarization mode coupling caused by stress field in PMFs (polarization maintaining fibers). In the measurement of polarization coupling, the birefringence in sensing fiber is usually considered to be wavelength-independent. The spatial resolution of the distributed stress sensor is invariable, when the optical source spectrum is given. In practical measurement, however, the birefringence in PMF is related with optical wavelength, the birefringence dispersion exists in PMF. Due to the birefringence dispersion, the spatial resolution of the distributed stress sensor descends obviously with the fiber length increasing. In this paper, the influence of external force position and optical source spectrum on spatial resolution in the distributed stress sensor is analyzed, while the birefringence dispersion is considered.

The Boron doped would increase the fibre's photosensitivity distinctly just when the dope content reach about 5%. Then the Boron content would get the saturation to influence the fiber's photosensitivity about 30%.

A new optical fiber Fabry-Perot (F-P) cavity sensor for liquid level detection was developed. The end of a flexible metal bellows, which can sustain a large strain displacement, is suggested to be one surface of the F-P cavity. Both electronic hardware and demodulation scheme in software were developed for fringes counting and direction discrimination of the liquid level. A scheme for temperature compensation was proposed. A prototype of the liquid level sensor was fabricated and the experiments for air pressure and water level measurement were carried out. Because the interference fringe counting technique was used for signal demodulation, the noise resistance capability of the sensor against optical power fluctuation and other disturbances is greatly improved.

The trade-off between resolution and signal to noise ratio is a shackle to develop high performance miniature grating spectrometers. Concentrating on breaking this shackle, freeform optics and super-resolution restoration method for miniature grating spectrometers are proposed in this paper. Substituting a varying sagittal surface for a toroidal one, not only aberrations along dispersive direction can be reduced, but also aberrations perpendicular to dispersive direction can be reduced in a broad spectral range. This means both resolution and throughput would be multiplied. To reduce the remnant imperfection of system, subpixel-deconvolution process may be supplemented. By subpixel reconstruction, under-sampling due to finite pixel size of array detector would be got rid of. By deconvolution, blurring duo to slit and other system imperfection would be eliminated. Consequently, resolution and throughput would be further increased.

Based on the current array CCD image sensor technology, integration time of each pixel sensitive unit in the CCD image sensor was controlled independently by way of adding circuits for pixel sensitive unit addressing and integration pulse generating. The integration time of the pixel sensitive unit was shortened appropriately when charges overflowed potential well of pixel sensitive unit in the array CCD Image Sensor, thereby achieving the aim of anti-blooming. The method was simulated by MATLAB and can obtain an ideal effect.

The visibility of Liquid Crystal Display (LCD) decreasing significantly while displaying motion picture, and how to evaluate Motion Picture Resolution of digital television has become a key concern. Motion picture resolution is a very important parameter for the evaluation of LCD and could be evaluated with smearing time according to national standards of PRC issued in 2006. Smearing time of LCD was measured using simulation method and SSPD pursuit tracking system. Simulation method was improved by introducing flash spectroradiometer and color alternate patterns. Camera pursuit tracking measurement system was established and SSPD was used instead of CCD. Results of experiments indicate that both black white pattern and color pattern could be measured effectively using these two improved methods and the camera pursuit tracking system's measurement resolution of smearing time could reach 0.3ms.

A spectrally resolving quantum dot photodetector has been designed and fabricated which is able to discriminate wavelengths in the visible region. The device consists of a monolayer of 5.4 nm diameter CdSe nanoparticles that have been sandwiched between two organic layers of Hexanedithiol, all on a highly doped p-type InP substrate. A thin, semitransparent layer of gold deposited on the top of the device made the second contact. The two layers of Hexanedithiol act as tunnel barriers for electrons inside the nanoparticles. Changing the bias voltage across the device, causes specific energy states inside the quantum dot to align with the conduction band edge of the InP. Any excited carriers in these energy levels will tunnel trough the organic barrier and be collected as photocurrent. The responsivity and noise equivalent power has been measured for two wavelengths.

This work was to introduce a reference mechanism in fiber based-SPR (surface plasmon resonance) sensors to increase their sensitivity. We fabricated two tandem SPR sections in a single optical fiber and coated one of the sections with a reference material to split a regular single resonant peak into two peaks, one in regular wavelength range for sensing and another one in longer wavelength range for referencing. By using the referencing peak to specifically detect the SPR changes caused by uncontrolled factors, such as temperature variation, non-specific bonding, we were able to subtract the contribution of these factors to the sensing peak using an established relationship, and thus increase the sensitivity of the sensing dip. With the method, we have demonstrated a fiber-based SPR humidity sensor whose sensitivity is immune to the variation of environment temperature.

In this paper, the thermal degradation mechanism of ultraviolet-induced fiber Bragg gratings (FBGs) written in silica fiber doped with germanium has been developed. The thermal degradation up to 840 oC has been repeatedly examined, and their reflectivity and Bragg wavelength change have been carefully observed. In addition, the temperature characteristic of the FBG is tested by putting it into a silica tube furnace heated from room temperature to 600 oC. The experiment results obtained has shown that the FBGs' thermal behavior is similar to a spring's. Therefore, a novel viewpoint, atomic elastic model applied to explain the thermal degradation mechanism of FBGs, is firstly present. The work is closely related to the use of FBGs for application in temperature sensor field, and the work is also related to form mechanism of FBGs.

Single-photon counting technology has been used extensively in testing due to its powerful quantitative performance for ultraweak luminescence intensity such as high time resolution and large dynamic range. However, some negative factors limit its performance in practice. In this work, the methods for weak signal detection and self-fitting noise suppression were applied to the signal processing in the single-photon counting system in which a photomultiplier tube (PMT) was the photoelectric sensor. Firstly, the weak signal from PMT was amplified by two stage amplifiers and subtracted by its means. And then the lost pluses were corrected by double discriminating voltages as different peaks' circumscriptions. Lastly it was proposed to put program-controlled auto compensation function for self-adjusting ability and high sensitivity. By these methods, the measure errors caused by narrow pulse interval and double-photons peak are decreased whilst the counting efficiency is increased. It was demonstrated that the performance of the single-photon counting system, in which signals were processed with the proposed methods, was enhanced and the system was more flexible in terms of self-fitting measuring.

The remote camera that is developed by us is the exclusive functional load of a micro-satellite. Modulation transfer function (MTF) is a direct and accurate parameter to evaluate the system performance of a remote camera, and the MTF of a camera is jointly decided by the MTF of camera lens and its CCD device. The MTF of the camera lens can be tested directly with commercial optical system testing instrument, but it is indispensable to measure the MTF of the CCD device accurately before setting up the whole camera to evaluate the performance of the whole camera in advance. Compared with other existed MTF measuring methods, this method using grating pattern requires less equipment and simpler arithmetic. Only one complete scan of the grating pattern and later data processing and interpolation are needed to get the continuous MTF curves of the whole camera and its CCD device. High-precision optical system testing instrument guarantees the precision of this indirect measuring method. This indirect method to measure MTF is of reference use for the method of testing MTF of electronic device and for gaining MTF indirectly from corresponding CTF.

GaAs films have been deposited on substrates of quartz glass by radio frequency magnetron sputtering technique in the atmosphere with or without hydrogen. The GaAs and hydrogen doped GaAs thin films have been studied by X-ray diffraction, scanning electron microscopy. Moreover radial distribution function and pair correlation function analysis method have been established in order to analyze microstructure further. The as-deposited films are amorphous at room temperature. The distances between the first neighboring atoms of a-GaAs:H don't change compared with a-GaAs:H. But Hydrogen restrains reuniting of crystal grain while sputtering and short range regular domains of a-GaAs:H are smaller than that of a-GaAs. In addition, the morphology of GaAs films is coarser than that of GaAs:H thin film. The content of hydrogen and the various types of hydrogen bonding have been investigated using Fourier transform infrared absorption spectroscope.

Dimensional measurement of hot parts, such as forgings, is desirable to permit real-time process measure and control, but typically it is not convenient as a result of the difficulty in working with very hot workpieces. On the contrary, the disadvantage of high temperature of the hot parts can properly be used to measure the dimensions based on CCD (Charged Coupled Device) sensors. It is well known that the hot parts can transmit lights, so the general CCD can be applied to measure the dimensions of the hot part (e.g. length and diameter etc.) rapidly and non-contact without any illuminator. Since the illumination system can be omitted, the measurement system can be more flexible and convenient. In this paper the principle of the measurement based on CCD is briefly described at first. Then the structure of measurement system is presented in detail. At last, some experiments are performed to measure the diameter of hot parts. The experimental results indicate that the measured diameter is correlated with the luminance of hot parts and the luminance has something to do with the temperature of the hot parts, and the methods to avoid this question are discussed. In addition, the error sources in the measurement system are also discussed. From these experiments, the method to measure the dimension of hot parts based on inexpensive CCD sensor is feasible.

In structured light vision measurement, it is vital to keep the measurement system stable because the system organization determines some important parameters used in 3D reconstruction. Aimed at this feature, a new camera calibration method is presented in the paper. This method utilizes a digital guide and a planar pattern to construct a visual 3D target. Through linear transformation and nonlinear optimization, the extrinsic and intrinsic camera parameters can be obtained iteratively. This method combines the merits of 3D pattern with planar pattern. The procedure of calibration is simple and convenient. The result is accurate by this method and meets the need of structured light vision measurement.

We used luminescent CdTe quantum dots (QDs) as energy donors and gold nanoparticles (AuNPs) as accepter in fluorescent resonance energy transfer (FRET) assays. CdTe QDs donors with 2.5 nm in size and AuNPs with 16 nm in size were synthesized, and more than 95% overlap between emission spectrum of the CdTe QDs and the absorption spectrum of AuNPs was confirmed. The synthesized donor and accepter were linked to 5' and 3' end of two designed complementary single-stranded DNA (ssDNA), respectively, sensing system was then composed by hybridizing the ssDNA into a double stranded DNA (dsDNA; i.e. CdTe-dsDNA-Au). The prepared CdTe QDs, AuNPs, and CdTedsDNA- Au were characterized by UV-vis spectra, fluorescence spectra, and electrophoresis method. Furthermore, FRET efficiency was estimated to be 74.6% for the FRET-pairs in dsDNA. The complementary single-stranded target-DNA was subjected to this sensing system to measure the fluorescence recovery. The dependence of fluorescence intensity on pH value, time, and amount of added target-DNA was investigated, respectively. The resulting data exhibited that pH 7.0 is optimum for both interaction of CdTe QDs and AuNPs and stability of DNA helix. After 12h of stand, the CdTedsDNA- Au sensing system becomes unstable. Fluorescence spectra of the sensing system showed that fluorescence recovery was enhanced with increasing addition of target-DNA in a certain range. Our data showed that an effective biosensing system was constructed base on fluorescent resonance energy transfer.

To achieve high quantum efficiency and good stability has been a main direction to develop GaAs photocathode recently. Through early research, we proved that variable doping structure is executable and practical, and has great potential. In order to optimize variable doping GaAs photocathode preparation techniques and study the variable doping theory deeply, a real-time quantum efficiency measurement system for GaAs Photocathode has been designed. The system uses FPGA (Field-programmable gate array) device, and high speed A/D converter to design a high signal noise ratio and high speed data acquisition card. ARM (Advanced RISC Machines) core processor s3c2410 and real-time embedded system are used to obtain and show measurement results. The measurement precision of photocurrent could reach 1nA, and measurement range of spectral response curve is within 400~1000nm. GaAs photocathode preparation process can be real-time monitored by using this system. This system could easily be added other functions to show the physic variation of photocathode during the preparation process more roundly in the future.

The primary objective of the Deci-hertz Interferometer Gravitational Wave Observatory (DECIGO) mission is to detect and observe black holes' and galactic binaries' gravitational waves (GWs), at frequencies ranging from 10-2 to 101 Hz. This low-frequency range is inaccessible to ground-based interferometers, due to unshieldable background noise, and the fact that ground-based interferometers are limited to a few kilometers in length. Our research is focused on efforts to stabilize semiconductor-, Nd:YAG- and fiber- lasers, for use as GW detectors' optical sources. In present-day- and future detectors' frequency- and phase-noise may place certain limitations on sensitivity and stability. Our goals (shared with scientists around the world) are; first, to design robust experiments that will measure a variety of noises (random-walk FM, flicker-FM, white FM, flicker PM and white PM), in order to verify existing models, and second, to find ways to reduce sensitivity to spurious noise. Current models predict a variety of frequency- and phase-dependent noise slopes, but, a conclusive distinction between noise-models can only be made when the exact points at which the noises occurred are known. In order to increase the sensitivity of the experiment, the laser frequency is stabilized to an atomic-frequency-reference by a feedback-loop control system.

As one of the key techniques of vision coordinates measurement, camera internal parameters calibration is regarded by technologists and has been researched a lot. Based on the study of regular internal parameters calibration methods such as plane calibration, two-plane calibration, vanishing points calibration, stereo calibration and so on, combined with the requirement of large space vision coordinates measurement for camera internal parameters calibration, this paper brings forward independent internal parameters calibration and virtual stereo calibration methods. A special calibration equipment is used in independent internal parameters calibration to calibrate original points coordinates of camera and distortion parameters of lens, and a virtual target board and bundle adjustment algorithm are used in virtual stereo calibration to calibrate internal parameters. They can be used in large space vision coordinates measurement and get high calibration accuracy.

Both conventional reflectance and electric modulation reflectance of MIS structures: Pt/BLT/Si and Pt/STO/Si are investigated under different bias voltage in visible band. To make the study for a novel type of infrared imaging device with optical readout, we describe theoretically the regularity of bias voltage-induced reflectivity change of MIS using Drude plasmon effect model and employ the electric modulation to enhance the sensitivity and resolution of reflectance spectrum of MIS. To improve the SNR for reflectance measurement, we design a dual-optical-path and dual-modulating experiment instrument. A tandem demodulation technique is adopted with two lock-in amplifiers to achieve precise results. Some more sensitive optical band for optical readout and the voltage value interval causing fastest change rate are found. With the MIS-based research, we bring out the possibility of forming the MFIS device for infrared imaging by attaching a ferroelectric layer PZT to MIS structure. The detecting principle of MFIS device is briefly introduced.

An optical system of 3D parameters measurement for specific area of a workpiece has been presented and discussed in this paper. A number of the CCD image sensors are employed to construct the 3D coordinate system for the measured area. The CCD image sensor of the monitoring target is used to lock the measured workpiece when it enters the field of view. The other sensors, which are placed symmetrically beam scanners, measure the appearance of the workpiece and the characteristic parameters. The paper established target image segmentation and the image feature extraction algorithm to lock the target, based on the geometric similarity of objective characteristics, rapid locking the goal can be realized. When line laser beam scan the tested workpiece, a number of images are extracted equal time interval and the overlapping images are processed to complete image reconstruction, and achieve the 3D image information. From the 3D coordinate reconstruction model, the 3D characteristic parameters of the tested workpiece are gained. The experimental results are provided in the paper.

During the production of Low-E (Low-Emission) glass, the distance between Low-E membrane reactor and the float glass impacts the thickness of Low-E membrane coated, and the quality of products. The system, designed to measure the displacement of the reactor, which represents the distance between Low-E membrane reactor and the float glass, will work in the industrial condition of high temperature and strong interference. On the consideration of non-contact, noninvasive and high-speed, a measure system by PSD (Position Sensitive Detector) based on Laser-Triangulation method is designed and a prototype made. In this system, a laser beam, generated by a semiconductor laser generator, focuses on the underside surface of the Low-E membrane reactor made of graphite. And then, the laser spot on the underside surface, through a small focus lens, is detected by a 1D-PSD (One-Dimension Detector). The electric signal, reflecting the position of the small laser spot on the PSD, is amplified and processed by amplifier and signal processing circuit, then is sampled by a A/D converter. Based on the Laser-Triangulation method, the displacement can be computed. Trial shows, the system based on Laser-Triangulation method meets the requirements of high-speed, noninvasive, non-contact, and to some extent diminishes the influence of nonlinearity and dark current of the PSD.

In this paper, a novel Q-switched fiber laser made up of OptoCeramic electrooptic ceramics is reported. The ring laser is composed with an electrooptic ceramics modulator as Q-switched, a highly Yb-doped fiber as the gain medium, and pumped by a semiconductor laser of 976 nm wavelength. Q-switched is realized from modulating the loss, controlled by the material refractive index, which is changed with the voltage of OptoCeramic element. The laser system generates pulses about 100ns, with the repetition rate continuously adjusted from 3kHz to more than 40 kHz.

Optical systems have been extensively studied for target recognition in a turbid medium because of its promising applications in many fields such as driver assistant system. Several recent studies have demonstrated that relevant information of the turbid medium including the hidden object in the medium can be derived by analyzing the polarization state of diffusely backscattered light of the sample. In this paper Stokes/Mueller formula was introduced to investigate polarized light transportation in a turbid medium such as atmosphere; Mie scattering theory was applied to calculate the scattering property of polarized light; Monte Carlo method was used to compute backscattered polarization patterns from a turbid medium containing hidden object. Results showed that the backscattered polarization patterns are strongly influenced by optical parameters of the medium. The two-dimensional distribution of degree of polarization (DOP) calculated from backscattered Mueller matrix can well discriminate different objects within limited distance. For applications in driver assistant system, the effective recognition distance in a foggy weather was also calculated; and results could be several times of visibility distance.

An advanced wavelength calibration process with higher wavelength accuracy is developed based on the conventional calibration method of micro-spectrometers with multichannel detectors. The deficiencies of the conventional method in acquiring sufficient well-spaced and adequately accurate wavelength-pixel data for calibration are analyzed. And three steps are added to the conventional method before the final pixel-wavelength fit is carried out. First, segmented data collection is carried out to ensure sufficient well-spaced lines for calibration. Second, sub-pixel analysis is executed to increase sampling rate. Third, peak fit is implemented to acquire more accurate central wavelength positions. The simulated experiment was based on a compact spectrometer with a crossed Czerny-Turner optical design. Mercury and Argon line spectra are used as wavelength standards. A linear image sensor with 1024 pixels each 25μm in width is used as the detector. In the new calibration process the whole spectral region was divided into two segments with different integral time of the detector; the sampling rate was increased by 2 times by sub-pixel analysis; and log-normal function is applied in the peak fit. The results show that by applying the new method, the wavelength accuracy improves from above 1.0nm to around 0.6nm.

Pt/AlGaN/AlN/GaN Schottky diodes have been fabricated and characterized for H₂ sensing. Platinum (Pt) with a thickness of 20nm was evaporated on the sample to form the Schottky contact. The ohmic contact, formed by evaporated Ti/Al/Ni/Au metals, was subsequently annealed by a rapid thermal treatment at 860°C for 30 s in N₂ ambience. Both the forward and reverse current of the device increased greatly when exposed to H₂ gas. The sensor's responses under different hydrogen concentrations from 500ppm to 10% H₂ in N₂ at 300K were investigated. A shift of 0.45V at 297K is obtained at a fixed forward current for switching from N₂ to 10% H₂ in N₂. Time response of the sensor at a fixed bias of 0.5 V was also measured. The turn-on response of the device was rapid, while the recovery of the sensor at N₂ atmosphere was rather slow. But it recovered quickly when the device was exposed to the air. The decrease in the barrier height of the diode was calculated to be about 160meV upon introduction of 10% H₂ into the ambient. The sensitivity of the sensor is also calculated. Some thermodynamics analyses have been done according to the Langmuir isotherm equation.

The CMOS active pixel sensor (APS) technology is of interest for space-borne instruments, such as low power imagers for micro-spacecraft, star trackers and machine vision for space micro-rovers. It is significant to evaluate image quality after the performance parameters of imaging system using CMOS APS are validated. The most fundamental of evaluating imaging quality is modulation transfer function (MTF). The system MTF is the multiplication of optics transfer function, detector transfer function and electronics transfer function. In CMOS APS arrays, the pixel area is constructed of two functional parts. The first part, which has a certain geometrical shape, is the sensing element itself: the active area that absorbs the illumination energy within it and turns that energy into charge carriers. The second part is the control circuitry required for readout of this charge. The ratio between the active area and the total pixel area is referred to as the fill factor (FF), which in APS is less than 100% (in contrast to CCDs where the FF can approach 100%). The preferred shape of the pixel active area is a square. However, designing the active area as a square can reduce the FF. Since the FF influences the signal and signal-to-noise ratio (SNR), it is preferred to keep it as high as possible. Theoretical analysis of the MTF for the active area shape is performed for an L shaped active area (most commonly used). And the effects of pixel active area shapes on imaging quality of CMOS active pixel sensor are analyzed.

We describe in this paper a laser-based digital displacement measuring system, which can detect displacement or deflection of an object in a long distance. It has the advantages of nor-contact, high resolution, fast response, and more importantly being remote. In order to achieve a remote measurement, the laser beam is first collimated, and directed to the detector array, which is attached to the remote object to be measured. The relative movement between the laser source and the detector will provide a measure to the displacement or deflection of the object. This system has three major features compared with the common laser-based displacement measurement systems. The first one, remote wireless digital signal and data transmission has been used in this measurement system, which increases the stability and practicability of the system. The second one, a laser level instrument has been used as a laser source, which makes it much easier to direct the laser beam to the detector at a long distance. The last one, MCU and LED have also been investigated, which makes the system more convenient. The measurement effect is proved by experiment. The academic measuring distance of the system is 100m and it is calibrated at a distance of 20m in the lab. The measuring frequency of the system is 29Hz. The error of the system is between -0.07mm to 0.07mm and the standard error is less than 0.05mm. The standard error of the system at an immovable point in four hours is 0.0134mm. Due to its features, perspective of its appreciation should be wide

PM2.5 is the chief air pollutants in most Chinese City. The PM2.5 parameter was usually evaluated by the weight per unit volume (mg/m³) and the size was generally ignored. A method measuring the particle size distribution of PM2.5 based on light scattering was put forward. A special sector sensor, SSPA(Self Scanning Photodiode Array), was designed to detect the distribution of weak space light energy. We researched a special optoelectronic detector with sector detection area. The sensor has high sensitivity and high reliability. It's suitable for detecting the distribution of space light energy, especially the diffraction and scattering energy distribution. The paper researched the signal processing method. Based on the principle and characteristics of SSPA, a signal acquisition and processing method controlled by computer was introduced. The amplification of weak signal, the matching of time sequence, the fast peak holding with low leakage, the high speed A/D conversion and nonlinear correction were discussed. The method can acquire the peak signal of every ring of sector SSPA with high accuracy and in real time. The particle size distribution of PM2.5 acquired in Hangzhou City was analyzed. Results showed that the particles with diameter below 2.5um were above 90%.

Parallel light projection method for the diameter measurement is to project the workpiece to be measured on the photosensitive units of CCD, but the original signal output from CCD cannot be directly used for counting or measurement. The weak signal with high-frequency noise should be filtered and amplified firstly. This paper introduces RC low-pass filter and multiple feed-back second-order low-pass filter with infinite gain. Additionally there is always dispersion on the light band and the output signal has a transition between the irradiant area and the shadow, because of the instability of the light source intensity and the imperfection of the light system adjustment. To obtain exactly the shadow size related to the workpiece diameter, binary-value processing is necessary to achieve a square wave. Comparison method and differential method can be adopted for binary-value processing. There are two ways to decide the threshold value when using voltage comparator: the fixed level method and the floated level method. The latter has a high accuracy. Deferential method is to output two spike pulses with opposite pole by the rising edge and the failing edge of the video signal related to the differential circuit firstly, then the rising edge of the signal output from the differential circuit is acquired by half-wave rectifying circuit. After traveling through the zero passing comparator and the maintain- resistance edge trigger, the square wave which indicates the measured size is acquired at last. And then it is used for filling through standard pulses and for counting through the counter. Data acquisition and information processing is accomplished by the computer and the control software. This paper will introduce in detail the design and analysis of the filter circuit, binary-value processing circuit and the interface circuit towards the computer.

When solar radiation transmits in the atmosphere, radiation wave band from 240nm to 280nm is strongly absorbed by the ozone layer, which makes the ultraviolet radiation in this wave band difficult to reach the near earth surface. It forms the solar radiation blind region on the near earth surface that is usually called solar blind region. Because of the strong absorption, the solar blind ultraviolet detecting system works in wee background noise condition. In this paper, we design a set of ultraviolet detecting experiment system. From the radiometry, we establish an improved estimate of the operating range model based on the target signal, background signal difference and noise of detector. Using the improved model, we can calculate the operating range for point target in solar blind ultraviolet detecting system. For the special ultraviolet target, the calculated values are consistent with the practically measured values in the experiment system designed in the paper.

Photoacoustic spectroscopy is a useful noninvasive technique for monitoring chemical composition in liquid. The resolution capability of photoacoustic methods is limited due to the low absorbance factor of some liquid. To increase effective absorbance distance of laser beams, two novel photoacoustic cell structures are introduced, in which multi-beam photoacoustic sources are produced respectively by zigzag reflection and inner-circle reflection of a single incident laser beam. Approximate surface acoustic waves can be produced in the two cell structures. The mathematical models are also labored, which can provide preliminary simulation results. Using which, A conclusion can be drawn that the acoustic pressure produced by the zigzag reflecting multi-beam acoustic source can reach at about 500 times than that produced by single-beam source with same incident laser power. A rough estimate can also be made that with a large number of reflecting, the acoustic pressure produced by the inner-circle reflecting multi-beam source can easily reach 50 times than that produced by single-beam source with same incident laser power.

To solve the problem of cross sensitization when the strain and the temperature are measured at the same time, we propose a structure of a ditrigon cantilever beam of uniform strength, realize a sensor structure in which the strain and the temperature can measured at the same time by a single fiber grating. The beam is bended and elongate the grating sticked on the surface of the beam, the reflectance spectrum from the grating is splitted into a double-peak spectrum. The strain can be measured by the space of the double peak. The variation of temperature is converted into the whole displacement of the reflectance spectrum.

This paper deals with experimental results on detection of toluene dispersed in water by means of a new and simple plastic optical fiber (POF) sensor. Its sensing part consists of swelling polymer cladding layer such as high density polyethylene (HDPE) with slightly larger refractive index n₂ than that of poly(methyl methacrylate) (PMMA) core with n₁. When is exposed to toluene dispersed in water, HDPE cladding layer causes swelling and the value of n₂ decreases quickly. Then the POF structure in the sensing part changes from leaky-type to guided-one and the output light intensity increases dramatically. By measuring this light intensity change, it becomes possible to detect toluene concentration. In addition, as compared with the popular evanescent-wave detection principle type, this sensor operation does not depend on the wavelength of light source. Therefore, we can use an inexpensive LED or LD in visible region. In experiment, detection of less than 1 wt% toluene in water was easily obtained with fast response about only 1 s. Furthermore, this sensor can detect pure toluene even for a small amount below 1 ml.

Recently, alcohols such as methanol and ethanol have a wide attention as important fuel in next generation. However, As is known, many alcohols have a toxic and explosive nature. To prevent accidents caused by alcohol, development of a safety and highly sensitive sensor is required strongly. In addition, it is desired to be simple and low-cost. So, in this paper, polymer waveguide-type optical alcohol sensors such as fiber-type and channel waveguide-type have been studied. In these sensor head, refractive index n₂ of cladding layer was set at slightly larger value than that of core (n₁). Therefore, in the state without alcohol, the sensor head operate as a leaky waveguide. On the other hand in the state with alcohol, cladding polymer causes swelling and its refractive index becomes lower than n₁ in core. Based on this principle, large change in output light intensity occurs and detection of alcohol concentration becomes possible even for vapor phase alcohol. In the experiment using a fiber-type sensor with a core size of 0.25 mm, detection of 1% methanol vapor could easily be obtained. Furthermore, using a channel waveguide-type sensor head with a core size of about 50μm×40μm, large increase in sensitivity was observed.

Combustible gases such as propane gas and methane gas are widely used in many homes and factories. However, accidents caused by gas leakage become a menace to everyday life. Therefore, development of quick and highly sensitive gas leakage sensor is required strongly. From these backgrounds, we have studied about plastic optical fiber (POF) gas leakage sensor because the POF have many advantages such as low-cost, light weight, immunity to electromagnetic noise. In this paper, the POF sensing system for multi-point gas leakages and its long term stability have been studied. In the experiment, gas concentration below 1% was detected for both propane gas and methane gas. This operation does not depend on a light wavelength. So, using several LED light sources with different wavelength, the POF sensing system for multi-point gas leakages was constructed. In the experiment using blue-, green- and red-LED, sensing of three-point gas leakages could successfully be obtained. Further more, considering its system for real application, long term stability of the sensor head was also checked and it was confirmed that the sensitivity does not change over 15 days.

Conversation is the most practical and common form in communication. However, people with a verbal handicap feel a difficulty to produce words due to variations in vocal chords. This research leads to develop a new devoiced microphone system based on distinguishes between the moisture patterns for each devoiced breaths, using a plastic optical fiber (POF) moisture sensor. In the experiment, five POF-type moisture sensors with fast response were fabricated by coating swell polymer with a slightly larger refractive index than that of fiber core and were set in front of mouth. When these sensors are exposed into humid air produced by devoiced breath, refractive index in cladding layer decreases by swelling and then the POF sensor heads change to guided type. Based on the above operation principle, the output light intensities from the five sensors set in front of mouth change each other. Using above mentioned output light intensity patterns, discernment of devoiced vowels in Japanese (a,i,u,e,o) was tried by means of DynamicProgramming-Matching (DP-matching) method. As the result, distinction rate over 90% was obtained to Japanese devoiced vowels. Therefore, using this system and a voice synthesizer, development of new microphone for the person with a functional disorder in the vocal chords seems to be possible.

This paper (SPIE Paper 682925) was removed from the SPIE Digital Library on 19 August 2008 upon learning that two individuals listed as additional co-authors on the manuscript had no prior knowledge of the paper, did not contribute to it, and did not consent to having their names included as co-authors. The names of these two individuals have been or will be deleted from this and all other bibliographic records as far as possible since they have no connection to this paper. Additionally, the remaining names associated with this publication record, Xiang-Wen Xiong and Wynn L. Bear, are actually the same individual and not two different authors. This is not sanctioned by SPIE. As stated in the SPIE Guidelines for Professional Conduct and Publishing Ethics, "SPIE considers it the professional responsibility of all authors to ensure that the authorship of submitted papers properly reflects the contributions and consent of all authors." A serious violation of these guidelines is evident in this case. It is SPIE policy to remove papers from the SPIE Digital Library where serious professional misconduct has occurred and to impose additional sanctions as appropriate.

A color digital Fresnel hologram has been recorded those complex amplitudes can be measured by six-step phase-shifting interferometry with the wavelength shifts of R, G and B tunable lasers. A six-step calculation is insensitive to the power change in tunable lasers. The wavelengths can be tuned by a current change of a red laser diode (LD), a cavity-length change of a green laser and an angle change in a grating of a Littman-type blue LD. Three monochromatic images are reconstructed from the numerical Fresnel diffraction integral and combined into a full-color image with CIE chromaticity. The experimental result of a full-color image reconstruction based on digital holography is shown.

The conventional phase-shifting interferometry (PSI) algorithm used in white-light phase-shifting interferometry (WLPSI) is not effective for the steep envelope change in the interferogram. We have developed a new 7-step algorithm that is insensitive to the steep contrast change in the envelope of interferogram. Seven-step algorithm includes the envelope change in the interferogram is approximated to be a parabolic function. The detection accuracy of the contrast peak and the accuracy in phase-extraction routine of a 7-step algorithm have been compared with those of a 5-step algorithm.