Journals >Opto-Electronic Engineering
Contents
2011
Volume: 38 Issue 6
26 Article(s)
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Research Article
A Fast CCD Measurement Method Used in Rendezvous and Docking
AN Kai, and MA Jia-guang
A two-CCD measurement system used in rendezvous and docking is designed, and the positioning algorithm of a marker lamp on target spacecraft is given with respect to a rendezvous and docking coordinate system. Then, the algorithm is extended to the case of three badge lamps, and accordingly the position, attitude matriA two-CCD measurement system used in rendezvous and docking is designed, and the positioning algorithm of a marker lamp on target spacecraft is given with respect to a rendezvous and docking coordinate system. Then, the algorithm is extended to the case of three badge lamps, and accordingly the position, attitude matrix and three attitude angles of target spacecraft are educed with respect to a rendezvous and docking coordinate system. Compared with the algorithm of computer vision, the algorithm proposed in this paper is simple, fast and proper to application in rendezvous and docking..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 1 (2011)
Dynamic Error Analysis of Facula Centroid Algorithm Based on CCD
JIN Zhan-lei, LIU Xue-feng, WANG Chun, and XU Li-na
The Linear Measure Instrument (LMI) based on image processing techniques is the major equipment for measuring the swinging mirror fixed on space infrared camera. Traditional error analysis methods neglect the facula streaking effect, so the measure uncertainty is increased. A model of facula displacement, pixel noise aThe Linear Measure Instrument (LMI) based on image processing techniques is the major equipment for measuring the swinging mirror fixed on space infrared camera. Traditional error analysis methods neglect the facula streaking effect, so the measure uncertainty is increased. A model of facula displacement, pixel noise and facula gray centroid algorithm is established. The model indicates that if the facula displacement in exposure time is far less than the static facula size, the dynamic measure error is closed to static measure error. However, if the ratio between facula displacement and facula static size is bigger than 6%, the variance of dynamic gray centroid algorithm error will be 20% more than static error variance. Then the exposure time shall be reduced and emergent power of light source shall be increased to reduce the dynamic measuring error of gray centroid algorithm..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 7 (2011)
Design of Parameters for Missile-borne Laser Altimeter with Dual-wavelength Outputs
ZHANG Yi-fei, YANG Hui, and WANG Xiao-tong
The terrain matching navigation system with radar altimeter is prone to be influenced by electronic interference, so the laser altimeter with infra-red/blue-green dual-wavelength outputs was designed to replace the radar altimeter for cruise missile. Furthermore, the hard problem could be resolved, i.e., the radar altiThe terrain matching navigation system with radar altimeter is prone to be influenced by electronic interference, so the laser altimeter with infra-red/blue-green dual-wavelength outputs was designed to replace the radar altimeter for cruise missile. Furthermore, the hard problem could be resolved, i.e., the radar altimeter couldn’t work over the sea, but the laser altimeter could. Based on laser altimetry/bathymetry equations and the output SNR expression, the digital simulation calculation was used to assess the performance of the laser altimeter. The simulation results show: the laser altimeter can satisfy the need of altimetry and bathymetry when the peak power of infra-red and blue-green pulses respectively reach 50 kW and 450 kW. At the same time, such parameters can be decided, including pulse energy, pulse width, pulse repetition rate, and divergence angle of laser beam, etc..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 12 (2011)
Modeling Raw Signals of Laser Altimeter Echo
ZHAO Xin, ZHANG Yi, WANG Xiang-jing, TU Bi-hai, ZHAO Ping-jian, and ZHANG Li-ming
It has been demonstrated that decomposing the return waveforms into a mixture of Gaussian components was suitable to achieve the information of the target. But the laser impulse is slightly asymmetric, and approximating the waveforms by using a sum of Gaussians may not be an accurate representation depending on the appIt has been demonstrated that decomposing the return waveforms into a mixture of Gaussian components was suitable to achieve the information of the target. But the laser impulse is slightly asymmetric, and approximating the waveforms by using a sum of Gaussians may not be an accurate representation depending on the application and target. This paper focus on the improvement of raw signal modeling and re.ne peak detection greatly increased the number of detected targets as well as their positional accuracy. More complex models than the Gaussian model, such as the Lognormal or generalized Gaussian functions, were introduced and. tted with backscatter waveform of canopy to improve the raw signal by LM algorithm. The results show, through introduction of new echo parameters, it is easy to extract the additional information on the target shape, and calculate reflectivity and roughness..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 18 (2011)
A Timing Control and Signal Processing Scheme of Laser Diode Ceilometer
HE Jun-feng, LIU Wen-qing, ZHANG Yu-jun, CHEN Zhen-yi, and RUAN Jun
Aerosol backscatter signal of laser diode ceilometer, acquired by using APD detectors, has relative low SNR, which can not be directly used for inversion of atmospheric parameters such as cloud height, vertical visibility. A timing control and signal processing scheme of laser diode ceilometer is presented, aiming at tAerosol backscatter signal of laser diode ceilometer, acquired by using APD detectors, has relative low SNR, which can not be directly used for inversion of atmospheric parameters such as cloud height, vertical visibility. A timing control and signal processing scheme of laser diode ceilometer is presented, aiming at the characteristics of backscatter signal. AD converter performs high speed data acquisition, and then DSP finishes cumulative average. Meanwhile, the complex timing control of the whole system’s transmitting receiving, maintenance, data saving, and uploading is performed. The comparison experiments show that the scheme works well, and can significantly improve the backscatter signal’s SNR to help the inversion of atmospheric parameters..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 24 (2011)
Triangulation and PSO-BP Neural Network Used in Star Pattern Recognition
ZHANG Shao-di, WANG Yan-jie, and SUN Hong-hai
In order to realize accurate measurement of aircraft’s current attitude, how to improve real time and robustness of star pattern recognition is the key of star sensor. The algorithms for star pattern abstraction, training sample set creation and network training improvement are proposed. First, a method of triangulatioIn order to realize accurate measurement of aircraft’s current attitude, how to improve real time and robustness of star pattern recognition is the key of star sensor. The algorithms for star pattern abstraction, training sample set creation and network training improvement are proposed. First, a method of triangulation based on the character of star image is designed to combine all the stars of current field of view, which is used to extract star pattern and create complete training samples. The character of star pattern extracted has the advantages of translation and rotation invariance. Then BP Neural Network serves to recognize the star pattern with the weight matrix instead of navigation library. It is very fast to acquire current star information when the network has finished training. Particle Swarm Optimization (PSO) serves to train BP Neural Network, which helps BP network converge to the most optimum value. The experimental results show that the success rate of accurate recognition is 100%..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 30 (2011)
Technology of Eliminating False Space Targets in Astronomical Opto-electronic Image Sequences
HUANG Zong-fu, HAN Jian-tao, and CHEN Zeng-ping
The false space targets are mostly caused by stellar targets, smears of stellar targets and space targets, background image and image noise. The performance of eliminating them directly affects the detection probability and false alarm rate of the whole system. Based on the detailed analysis of the origin of false spacThe false space targets are mostly caused by stellar targets, smears of stellar targets and space targets, background image and image noise. The performance of eliminating them directly affects the detection probability and false alarm rate of the whole system. Based on the detailed analysis of the origin of false space targets, the methods of eliminating them are proposed according to their different features in images: 1) eliminating false space targets using their basic imaging features; 2) eliminating the false targets on smears of stellar targets and space targets by detecting the smears; 3) eliminating false space targets which come from stellar targets based on the changing of the temporal difference processing images and based on the variety of region images which include targets respectively; 4) confirming space targets with track information. Finally, combining with the hardware platform and real-measured data, the effectivity and real-time performance of methods are validated..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 38 (2011)
Vignetting Correction Method of Assembled Images Using Reflector
TAO Ming-hui, REN Jian-yue, ZHANG Yu, ZHANG Xing-xiang, and LI Xin-e
According to the gray distribution character of vignetting image photographed by interleaving assembled CCD camera using reflector, the method of two-dimensional quadrics fitting based on steepest descent method is introduced in this paper to solve the problem. The gray compensation algorithm based on two-dimensional qAccording to the gray distribution character of vignetting image photographed by interleaving assembled CCD camera using reflector, the method of two-dimensional quadrics fitting based on steepest descent method is introduced in this paper to solve the problem. The gray compensation algorithm based on two-dimensional quadrics fitting using matlab simulation is introduced after the analysis of the vignetting physical model of interleaving assembled CCD camera using reflector. Parameters of Hesse matrix are also deduced at the same time. The simulation result has illuminated that the parameters of irregular two-dimensional quadrics, such as vignetting image gray level, can be estimated effectively by this method. The actual processing result shows the vignetting phenomenon can be removed effectively, and consequently the quality of image is improved. We have used the new algorithm to restore 782×582 gray image on the test platform, the programme’s running time is 24 ms, so the algorithm can completely meet the practical need of the projects. Since no relative optical and geometrical parameters are needed, this method can be widely used in projects..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 45 (2011)
The Influence and Control of Wind Loading on the
One Meter Solar Telescope Servosystem
LIU Guang-qian, CHENG Xiang-ming, SONG Teng-fei, and ZHAO Xue-juan
The performance of one meter solar telescope position control servosystem was influenced seriously by wind disturbances, because of its special optic and mechanical structure and open observation mode. Therefore its servosystem was required to achieve good disturbance rejection. At first, the telescope’s optic and mechThe performance of one meter solar telescope position control servosystem was influenced seriously by wind disturbances, because of its special optic and mechanical structure and open observation mode. Therefore its servosystem was required to achieve good disturbance rejection. At first, the telescope’s optic and mechanical properties were described, and then mathematical model and numerical simulation of its soversystem was presented. Furthermore, the rate and position controllers’ abilities to minimise the effect of wind disturbance were analysed in depth. On the premise of servosystem’s stabilisation, to improve servosystem’s stiffness by increasing servosystem’s gain can meet the demand of the telescope working normally under the condition.of moderate breeze disturbance. In the end, experiment results about servosystem performances and short time tracking accuracy were provided. The results show that the servosystem can achieve the tracking precision required of the telescope’s scientific goals and terminal instruments..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 50 (2011)
Design and Simulation of Parallel Optical Data Storage System
SU Ya-hui, CUI Hong-tao, YANG Yun-jie, WANG Jin-li, and HUANG Wen-hao
Traditional three-dimensional optical data storage is limited by the defect of inefficiency due to its serial written mode. To overcome this disadvantage, a modified parallel optical data storage system is proposed. This system utilizes Digital Micro mirror Device (DMD) as spatial light modulator, through which the incTraditional three-dimensional optical data storage is limited by the defect of inefficiency due to its serial written mode. To overcome this disadvantage, a modified parallel optical data storage system is proposed. This system utilizes Digital Micro mirror Device (DMD) as spatial light modulator, through which the incident light is modulated as designed. In succession, the emergent light is focused respectively by a microlens array, giving rise to a controllable focal spots array. The system is modeled and simulated by ZEMAX and Matlab, and the design of a microlens array based on the parameters of the existing system is also demonstrated. At last, the result of the simulation is presented in this paper, from which the conclusion that this system could realize parallel data storage with optical switch is drawn..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 59 (2011)
The Development of Parallel Confocal Microscope
Employing Digital Micromirror Device
ZHANG Yun-bo, HOU Wen-mei, ZHENG Ji-hong, and GUAN Zhi-chao
A multi-point parallel confocal microscope is designed and developed based on Digital Micromirror Device (DMD). Operated with specific patterns, the DMD can modulate light source into multiple beams. The DMD functions as virtual pinhole array and takes the place of traditional pinholes to realize the lateral scanning tA multi-point parallel confocal microscope is designed and developed based on Digital Micromirror Device (DMD). Operated with specific patterns, the DMD can modulate light source into multiple beams. The DMD functions as virtual pinhole array and takes the place of traditional pinholes to realize the lateral scanning technique. According to the research, the DMD based confocal system can achieve parallel scanning in the case of ensuring axial resolution. In that way, it can not only increase the inspecting speed, but also programmablely control the key parameters of the system, such as pinhole size and frequency. The inner surface reflection interference of the beamsplitter prism was eliminated, and a transverse scan strategy was designed. By carrying out experimental measurement on the prototype, depth response curve was acquired and the three-dimensional profile of the target object was successfully restored..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 65 (2011)
Output Model and Simulation for Optical Field with Metrological Grating Space Pose Parameters
HU Yi, FEI Ye-tai, and YE Si-ran
Metrological gratings are now widely used in such fields as precision measurement, numerical control machine and so on. The mutual position change between instruction grating and scale grating of the sensor during grating installation or application procedure will result in the distortion of Moiré fringe, which diMetrological gratings are now widely used in such fields as precision measurement, numerical control machine and so on. The mutual position change between instruction grating and scale grating of the sensor during grating installation or application procedure will result in the distortion of Moiré fringe, which directly influence the measurement accuracy and complexity degree for following process system. In this paper, Fourier spectrum analysis method was applied to build the optical field output model involving instruction grating and scale grating pose parameters, to introduce the mathematic formulas for output optical field with the two gratings unparallel mutually and to detailedly analyze the main influencing factors, all of which are simulated in Matlab. Moreover, this paper gave Moiré fringe error values and their variation trend for different assembling offset angles, discussed measuring results affected by configuration dimension of receiving sensor and obtained that the receiving system with its dimension the same as Moiré fringe had the minimum measuring error. The results are of great guiding for accuracy and configuration design of grating couples..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 71 (2011)
Differential Interference Contrast Method Based on Bi-frequency Grating
XIN Xue-cheng, ZHANG Yu-dong, LI Guo-jun, WANG Jiong, and LUO Xian-gang
A new Differential Interference Contrast (DIC) method is proposed based on the DIC theory by replacing the two Nomarski prisms of conventional DIC with bi-frequency blazed gratings, which overcomes the drawbacks of artifacts in the conventional DIC technology. The Bi-frequency blazed gating has been designed, and intenA new Differential Interference Contrast (DIC) method is proposed based on the DIC theory by replacing the two Nomarski prisms of conventional DIC with bi-frequency blazed gratings, which overcomes the drawbacks of artifacts in the conventional DIC technology. The Bi-frequency blazed gating has been designed, and intensity distributions of plane wave through the grating also have been numerically simulated. The pure phase object and its image are simulated by utilizing grating DIC, and the image agrees with the phase profiles of object very well. Analysis of the influence of shear and bias on the contrast of image demonstrates that image contrast is obviously enhanced when a bias retardation is introduced, and the smaller shear, the higher contrast..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 78 (2011)
Design of Four-fiber Collimator Based on a Variable-curvature Lens
ZHANG Ming, WEI Zhen, and LE Zi-chun
A four-fiber collimator based on four-fiber header and a variable-curvature lens has been developed for a novel Reconfigurable Optical Add-Drop Multiplexer (ROADM). The variable-curvature surface consists of two spheres. The four fibers are arranged equidistantly and parallelly in one plane, then four light rays from tA four-fiber collimator based on four-fiber header and a variable-curvature lens has been developed for a novel Reconfigurable Optical Add-Drop Multiplexer (ROADM). The variable-curvature surface consists of two spheres. The four fibers are arranged equidistantly and parallelly in one plane, then four light rays from the fibers pass through different part of the lens so that the angle of output light from the collimator can satisfy the application requirement. When the output facets of fibers are at the object focus of the variable-curvature lens, the light emitted from the fiber could be collimated. By using matrix optics method, the structure parameters of the four-fiber collimator, such as spheric radius and lens length, were obtained. The propagation of light field in the device was stimulated by RSOFT, from which energy concentration over 90% come under observation..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 84 (2011)
Piezoelectric Ceramic Fiber Phase Modulation
System and Its Online Calibration
ZHANG Chao, DUAN Fa-jie, JIANG Jia-jia, and WANG Ka
A low-cost, low-noise, high-precision piezoelectric ceramic fiber phase modulation system is designed, including ± 100 V linear regulator, ± 12 V linear power supply and the transistor drive circuit of piezoelectric ceramic. ± 100 V power supply’s ripple voltage is less than 10 mV, the circuit noise figuA low-cost, low-noise, high-precision piezoelectric ceramic fiber phase modulation system is designed, including ± 100 V linear regulator, ± 12 V linear power supply and the transistor drive circuit of piezoelectric ceramic. ± 100 V power supply’s ripple voltage is less than 10 mV, the circuit noise figure is less than 2 dB, 3 dB bandwidth is greater than 500 Hz, peak output is more than 160 V and the output current is greater than 100 mA. Through 3 dB coupler forming fiber optic Michelson interferometer and optical fiber end reflection interference signal to online calibration, the nonlinear of phase modulation is less than 5%..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 89 (2011)
The Improvement of Spectral Properties and Thermal Stability of Er3+-doped Tellurite Glasses
WANG Sen, ZHOU Ya-xun, DAI Shi-xun, WANG Xun-si, SHEN Xiang, WU Yi, and XU Xing-chen
Er3+-doped tellurite glasses with composition in mol percent of 70TeO2-20(ZnO, WO3, AlO1.5)-9NaO0.5-1ErO1.5 were prepared by conventional melt-quenching method. The absorption spectra and the fluorescence spectra of the glasses were measured, and the thermal stability of the glasses was measured by the Differential TheEr3+-doped tellurite glasses with composition in mol percent of 70TeO2-20(ZnO, WO3, AlO1.5)-9NaO0.5-1ErO1.5 were prepared by conventional melt-quenching method. The absorption spectra and the fluorescence spectra of the glasses were measured, and the thermal stability of the glasses was measured by the Differential Thermal Analysis (DTA) technique. The glass internal structure was analyzed, and the bandwidth quality factor ( σepeak × FWHM ) and gain quality factor σ were compared among the three glasses based on the intensity parameters. t (t=2, 4, 6) calculated by (mpeakeτ×) Judd-Ofelt theory, and the Er3+ absorption cross-section and stimulated emission cross-section calculated by McCumber theory, respectively. The results show that the bandwidth quality factor can be enhanced by 1.3 and 1.6 times, and the gain quality factor can be enhanced by 1.2 and 1.4 times when the composition ZnO in the tellurite glass was replaced by WO3 and Al2O3, respectively. Furthermore, the thermal stability was increased evidently in the glass containing Al2O3. The studies indicate that the spectral properties and thermal stability of Er3+-doped tellurite glass can be improved through the change of glass constituent..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 93 (2011)
FTIR Data Processing Method of High-precision
LI Li-gong, YIN Zong-liang, YU Xiao-fen, and LI Bao-sheng
In order to measure the infrared spectrum accurately, a high-precision Fourier Transform Infrared spectroscopy（FTIR）data processing system has been established. Some methods, such as apodization, phase correction, and wave number correction were researched. Compared with the two sides of window functions, Fourth-order In order to measure the infrared spectrum accurately, a high-precision Fourier Transform Infrared spectroscopy（FTIR）data processing system has been established. Some methods, such as apodization, phase correction, and wave number correction were researched. Compared with the two sides of window functions, Fourth-order Blackman window function was used for apodization of the interferogram, using convolution of unilateral interferometers for phase correction according to the characteristics of infrared interferometers phase error, further researched the number of wave energy calibration method of gravity wave number correction. Experimental results show that the spectra can be accurately measured by the Fourier transform infrared spectroscopy data processing system, and the accuracy of the wave number can increase 5 to 10 times under the condition of the wave number overlaps seriously, and the parameter would improve more than 103 times when the overlapping condition of the wave number is not serious. The Fourier transform infrared spectroscopy data processing system could meet the challenge of accurate measurement of the infrared spectrum..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 99 (2011)
Experimental Study of Laser-induced Fluorescence of Anthracene in Soil
HE Jun, DENG Hu, WU Zhi-xiang, and MA You-liang
It is complicated to detect Polycyclic Aromatic Hydrocarbons (PAHs) contamination soil by High Performance Liquid Chromatography (HPLC) with the conventional method. the Laser-induced Fluorescence (LIF) is used to on-site detect anthracene, one of the PAHs in soil, and it is shown that the Laser-induced Fluorescence caIt is complicated to detect Polycyclic Aromatic Hydrocarbons (PAHs) contamination soil by High Performance Liquid Chromatography (HPLC) with the conventional method. the Laser-induced Fluorescence (LIF) is used to on-site detect anthracene, one of the PAHs in soil, and it is shown that the Laser-induced Fluorescence can facilitate the monitoring of the soil pollution. According to the fluorescence properties of anthracene, the optical path and sample holder are designed to directly excite the fluorescence of the mixture of anthracene and the soil sample by using Nd: YAG laser at 355 nm, and the fluorescence spectra are recorded by the fiber spectrometer. It is shown that there are obvious emission fluorescence peaks at 375 nm, 391 nm, 419 nm and 445 nm, and different mass fractions exhibit good linearity to the fluorescence intensities with the correlation coefficients up to 0.999. The effects of the changes in experimental conditions on the fluorescence properties of anthracene are studied, and it is demonstrated by experiment that it is feasible to on-site quantitatively detect anthracene in the soil by using Laser-induced Fluorescence..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 105 (2011)
On-line Measurement of Surface Roughness Based on Laser Two-dimensional Scattering Principle
ZHANG Qiu-jia, ZHAO Yu-hua, HAN Dong, YU Ping, and LIU Ming-zhu
Referring to the complicated operating and bad field measuring of existing surface roughness, an on-line measurement method is presented based on laser two-dimensional scattering principle. The method proposed can not only measure the surface roughness parameters, but also figure out the surface topography. In this meaReferring to the complicated operating and bad field measuring of existing surface roughness, an on-line measurement method is presented based on laser two-dimensional scattering principle. The method proposed can not only measure the surface roughness parameters, but also figure out the surface topography. In this measurement, by using non-diffraction laser beam as light source and high accuracy CCD camera as displacement sensor, and applying the method of signal processing of surface roughness by Matlab, real-time measurement of surface roughness can be realized. This method is realized with modularized design, and has the advantages of simple structure, powerful real-time processing capability, high-precision measurement, visual display, and easy operation, etc..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 110 (2011)
Weak Optical Background Elimination Based on
the Acousto-optical Delay Effect
GAO Yan, ZHANG Guo-feng, WANG Xiao-bo, XIAO Lian-tuan, and JIA Suo-tang
A method for eliminating the weak optical background is presented in the pulse laser transmitting using the acousto-optical delay effect. The background photons with the same optical frequency of the pulsed laser can be suppressed effectively by using two tandem acousto-optic modulators working as optical switches. TheA method for eliminating the weak optical background is presented in the pulse laser transmitting using the acousto-optical delay effect. The background photons with the same optical frequency of the pulsed laser can be suppressed effectively by using two tandem acousto-optic modulators working as optical switches. The signal to noise improvement ratio is up to 13 dB. Here, the first acousto-optic modulator is used to separate the pulse signal and the background photons in time domain. The second one is used to notch the separate background photons. This method could be applied in the range of precision measurement and information processing for pulse light sensitive detection..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 115 (2011)
The Response of a One-dimensional Position Sensitive
Detector under General Point Light Sources
KONG Ling-chen, LI En-pu, YANG De-xing, and XING Hui
A PSD is modeled as an approximate Linear Time Invariant (LTI) system based on the rc transmission line model and the impulse response obtained from Lucovsky equation. Based on the model, the PSD general response is derived. In our processing, a time-varying light signal is divided into many sections in time domain. EaA PSD is modeled as an approximate Linear Time Invariant (LTI) system based on the rc transmission line model and the impulse response obtained from Lucovsky equation. Based on the model, the PSD general response is derived. In our processing, a time-varying light signal is divided into many sections in time domain. Each section is regarded as a square-wave pulse. And the response is approximated to be a linear superposition of those pulse responses. Results show that the response is the summation of product of two factor sequences: one factor is the inherent decay factor and the other is the outer incentive response factor. In addition, analysis on Alternating Current (AC) response by virtue of the general response shows that there is hysteretic fluctuation with light intensity change and the current response is insensitive to high-frequency AC optical signals..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 120 (2011)
A Watermarking Algorithm for Print Forgery Prevention Based on
Comparison between Norm and Mean of Norm
YE Tian-yu
At present, those existing watermarking algorithms for print forgery prevention always embed watermarks into original images, and their invisibility needed to be improved. Moreover, they had never studied their robustness against dual print-and-scan process. A watermarking algorithm for print forgery prevention was proAt present, those existing watermarking algorithms for print forgery prevention always embed watermarks into original images, and their invisibility needed to be improved. Moreover, they had never studied their robustness against dual print-and-scan process. A watermarking algorithm for print forgery prevention was proposed to overcome those problems based on the comparison of numerical relationship between norm and mean of norm. It conducted discreet wavelet transformation on the original image, split its low frequency band into non-overlapping blocks, and conducted singular value decomposition on each block. The zero-watermark sequence was derived from judging the numerical relationship between singular matrix’s norm from each block and mean of singular matrix’s norm form all blocks. It has perfect visibility due to no alteration made to the original image. The experimental results show that it has the ability to resist both single print-and-scan process and dual print-and-scan process..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 126 (2011)
Identifying Size of Motion-blurred Image Based on Difference Auto-correlation Method
GUO Yong-cai, DING Xiao-ping, and GAO Chao
It was important to identify Point Spread Function (PSF) accurately in blind motion-blurred image restoration. When we knew motion-blurred direction, the two-dimensional PSF problem could be transformed into one-dimensional problem. We used the first order difference auto-correlation method to identify motion-blurred sIt was important to identify Point Spread Function (PSF) accurately in blind motion-blurred image restoration. When we knew motion-blurred direction, the two-dimensional PSF problem could be transformed into one-dimensional problem. We used the first order difference auto-correlation method to identify motion-blurred size. This method was proved feasibly in theory. Then we researched and deduced the influence of noise particularly. In order to tackle the noise problem, the improved method was put forward. Experiment results on simulated images show accuracy to identify size. And our improved method enhances robustness to noise. At last, using proposed method to identify the size of the real motion-blurred image, the distinct restored image also validates the usability and validity of the proposed method..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 134 (2011)
A Modified Anisotropic Diffusion Denoising Scheme Based on the Correlation Coefficient
ZHANG Hong-min, and ZHANG Ya-juan
The classical Perona-Malik anisotropic diffusion model can not remove the image noise while edge preserving effectively because it just considers the gradient information of the image. A novel modified anisotropic diffusion denoising scheme was proposed based on the correlation coefficient, which incorporates both the The classical Perona-Malik anisotropic diffusion model can not remove the image noise while edge preserving effectively because it just considers the gradient information of the image. A novel modified anisotropic diffusion denoising scheme was proposed based on the correlation coefficient, which incorporates both the local gradient and the local gray variance information of the pixels in an image. Experimental results show that the proposed model can obtain better noise removing and edge keeping simultaneously than the traditional Perona-Malik model, and it has some generality and a certain application value in the image denoising..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 141 (2011)
A Fast Electronic Image Stabilization Algorithm of Video Sequences Based on Gray Projection and Block Matching
ZHAO Zhi-qiang, and CHEN Ying
In allusion to the instability of video sequences, a new electronic image stabilization algorithm, based on different features of gray projection algorithm and block matching algorithm, is proposed to fast eliminate the shift, dithering and rotation of video sequences. This algorithm first adopts gray projection algoriIn allusion to the instability of video sequences, a new electronic image stabilization algorithm, based on different features of gray projection algorithm and block matching algorithm, is proposed to fast eliminate the shift, dithering and rotation of video sequences. This algorithm first adopts gray projection algorithm to reckon and compensate the translational motion between video sequences, and then adopts Laplace operator to select small templates with abundant gray-scale information near the edge of the image. Next, it uses block matching algorithm to calculate the translational motion of templates. Moreover, it reckons the image rotation according to where the templates locate on the image. In the end, it uses motion compensation to attain stable video sequences. Experimental results show that, the algorithm can obviously eliminate the dithering between video sequences, which will have a salutary effect on improving the stability of dynamic image..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 6, 146 (2011)
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