Journals >Opto-Electronic Engineering
Contents
2010
Volume: 37 Issue 5
27 Article(s)
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Research Article
Analysis and Calculation of Coating Stealth Targets with Passive Millimeter Wave Detection System
NIE Jian-ying, LI Xing-guo, and LOU Guo-wei
Millimeter wave characteristics differ from those of microwaves, infrared or optical system, and it has some distinct advantages over microwave, infrared, or optical system. Nowadays, precision guided weapons or end-sensing-cartridges are often two active and passive modes of operation for a millimeter wave seeker. In Millimeter wave characteristics differ from those of microwaves, infrared or optical system, and it has some distinct advantages over microwave, infrared, or optical system. Nowadays, precision guided weapons or end-sensing-cartridges are often two active and passive modes of operation for a millimeter wave seeker. In view of the characteristics of the coating-stealth objections, we deal with a new method for anti-coating-stealth objective by passive millimeter wave seeker system. The principle of coating-stealth targets to be detected with passive millimeter wave seeker was analyzed. Then, according to data of antenna temperatures resulted from the coating stealth targets, a method for calculating the minimum variance and the best value of the coating-stealth target’s radiation temperatures with passive millimeter wave seeker was introduced. Moreover, the experimental data with 3mm passive radiometer were analyzed. Finally, simulation learning curve was given..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 1 (2010)
Fast Template Matching for Incomplete Target
DENG Ze-feng, XIONG You-lun, and HUANG Xiao-peng
A novel fast template matching algorithm for incomplete target searching based on block statistics was presented. This algorithm divided the template and the candidate image into several blocks with the same size. Absolute distance was used to calculate the pixel matching degree between the corresponding pixels. Then, A novel fast template matching algorithm for incomplete target searching based on block statistics was presented. This algorithm divided the template and the candidate image into several blocks with the same size. Absolute distance was used to calculate the pixel matching degree between the corresponding pixels. Then, the block matching degree and the target matching degree were proposed by statistical method. In order to speed up the searching process, the pyramid of the multi-level images was built. Experimental results demonstrate that the proposed algorithm performs well on locating both the complete targets and non-complete ones. The execution time is limited to several milliseconds and the algorithm has strong noise immunity..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 7 (2010)
Ensemble Contour Tracking
WEI Zi-fu, BI Du-yan, XU Jian-jun, and NAN Qin-bo
Tracking is considered as a binary classification problem in this paper, and a novel contour tracking algorithm is proposed based on Adaboost ensemble learning and fast level set. First, an ensemble of weak classifiers is trained online to distinguish between the target and the background. Then, the ensemble of weak clTracking is considered as a binary classification problem in this paper, and a novel contour tracking algorithm is proposed based on Adaboost ensemble learning and fast level set. First, an ensemble of weak classifiers is trained online to distinguish between the target and the background. Then, the ensemble of weak classifiers is combined into a strong classifier using AdaBoost and the strong classifier is used to label pixels in the next frame as either belonging to the object or the background, so the velocity function of fast level set is obtained. Contour tracking is realized by evolving the zero level set curve using dynamic neighbor region fast level set algorithm which is proposed in this paper. Temporal coherence is maintained by updating the ensemble with new weak classifiers that are trained online during tracking. Experiments show that this algorithm can track the target contour under the conditions of moving background, illumination variation, partial occlusion and the scale change of target..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 12 (2010)
Multi-closed Loops Cascade Control for Stabilization of Inertia Platform
LI Zhi-jun, BAO Qi-liang, MAO Yao, TANG Tao, and CHEN Xing-long
Considering the shortcomings of single rate-loop servo control composed of rate gyro for stabilization of inertia platform, a dual rate-loop cascade control structure is presented, which uses the DC tachometer to constitute the digital inner loop, and uses the rate gyro to constitute the digital outer loop. In the tracConsidering the shortcomings of single rate-loop servo control composed of rate gyro for stabilization of inertia platform, a dual rate-loop cascade control structure is presented, which uses the DC tachometer to constitute the digital inner loop, and uses the rate gyro to constitute the digital outer loop. In the tracking control system, using PI controller, we achieved a ternary closed loops cascade control mode which is constituted of current, inner velocity and outer velocity loop, and then, compared it with a dual closed loops cascade control mode which is constituted of current, and velocity loop. The experimental results show that the single rate-loop cascade control mode is better in high- frequency disturbance, while dual rate-loop cascade control mode gets better stabilization precision in low-frequency disturbance and better functions of rejecting friction disturbance..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 19 (2010)
The Technology of Asynchronous Laser Transponder
TANG Jia, GAO Xin, XING Qiang-lin, LI Jian-ting, and YANG Fu-min
The asynchronous laser transponder can greatly enhance the functional distance of the satellite laser ranging. The formulae are deduced for the delay between the laser departure from the two terminals (the clock offset), the range between the dual stations, and the measuring time for the range. The formula of the clockThe asynchronous laser transponder can greatly enhance the functional distance of the satellite laser ranging. The formulae are deduced for the delay between the laser departure from the two terminals (the clock offset), the range between the dual stations, and the measuring time for the range. The formula of the clock offset is different from the classical formula and the practical formula applied in radio ranging. In order to get the correct formula of the clock offset, achieve the ranging error and verify the engineering feasibility, we designed and carried out the verifying experiment for asynchronous laser transponder. This experiment is also the first application of the new method of asynchronous laser transponder in our country. The experimental result shows that the asynchronous laser transponder system is feasible, which proves that our formula for the clock offset is correct. The accuracy of the new method locates the accuracy of reflex ranging of both terminals..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 25 (2010)
Quantitative Analysis of Laser Speckle Removal
XU Qiu-yun, LI Ya-nan, ZHAI Wen-chao, and ZHENG Xiao-bing
In the newly developed laser-illuminated integrating sphere source, speckle in the image from the source is effectively removed by rotating diffusers in the sphere to improve the uniformity and stability of the radiation field. The specific relationship between the speckle removal effect and the rotation frequency of tIn the newly developed laser-illuminated integrating sphere source, speckle in the image from the source is effectively removed by rotating diffusers in the sphere to improve the uniformity and stability of the radiation field. The specific relationship between the speckle removal effect and the rotation frequency of the diffusers is evaluated. Speckle contrast of the exit port image is calculated under different rotating speed and different CCD integrating time. We have checked that the speckle noise is reduced to a negligible level by rotating the diffuser at very low frequencies. The speckle contrast is approximately 30% when the diffusers are motionless, and it is reduced to 5% when the speckle is removed..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 32 (2010)
Gun Bore Flaw Image Recognition Based on Power-amplitude Spectrum
LI Yu-lan, ZHENG Hai-qi, WANG Ping, YUAN Rui-hong, TANG Li-wei, and LUAN Jun-ying
In gun bore flaw detection based on machine vision, computer can not recognize flaw image with typical idea, such as target segmentation, feature extraction, feature analysis and judgment. Aiming at this problem, twice-spectrum analysis method was adopted to extract flaw information from overall features of image. ImagIn gun bore flaw detection based on machine vision, computer can not recognize flaw image with typical idea, such as target segmentation, feature extraction, feature analysis and judgment. Aiming at this problem, twice-spectrum analysis method was adopted to extract flaw information from overall features of image. Image twice-spectrum was defined as logarithmic amplitude spectrum of power spectrum. And four parameters, which were Length-to-Width Ratio of Bright Straight Line, Energy Mean, Energy Variance and Energy Moment, were extracted to analyze gun bore images. The experimental results testify rationality of the parameters..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 37 (2010)
Measurement Technology of Shock Wave Velocity in the Transparent Material
WANG Feng, PENG Xiao-shi, LIU Shen-ye, LI Yong-sheng, JIANG Xiao-hua, and DING Yong-kun
The technique to measure directly the shock wave velocity in the transparent material for the ultra-high pressure is introduced. The optical lane and the basic rule for this technique is provided, and the time sequence of preheat effect and shock wave is analyzed. From the experiment data, it is found that the beginninThe technique to measure directly the shock wave velocity in the transparent material for the ultra-high pressure is introduced. The optical lane and the basic rule for this technique is provided, and the time sequence of preheat effect and shock wave is analyzed. From the experiment data, it is found that the beginning point of preheat effect caused by X-ray is consistent with the laser pulse, and the preheat effect is the worst when the intensity of laser pulse is highest. The shock wave is later than the preheat effect. The reflection signal increases when the shock wave reaches the planar-window material. This increasing for reflection signal can be regarded as the beginning point of shock wave. The experiment data shows that the stripe loss is caused by the preheat effect. The preheat effect appear as soon as the flat of laser pulse transfers into the target cavity, and it decrease too low to disturb the detecting of shock wave after 400ps at the end of flat of laser pulse. The decreasing curve in the sapphire is confirmed by the comparison of experiment data and theoretical analysis. The formula to calculate the shock wave velocity is provided, and it is conformed by the experiment data..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 41 (2010)
Camera Calibration Based on PSO and LSSVM Regression
LIU Jin-song, YUAN Si-cong, JIANG Xiang-kui, and DUAN Zhi-shan
Aiming at the difficulty of establishing accurate mathematical model of camera in explicit non-linear calibration, a new implicit non-linear camera calibration method based on Particle Swarm Optimization (PSO) and Least Square Support Vector Machine (LSSVM) regression was proposed. A least square support vector regressAiming at the difficulty of establishing accurate mathematical model of camera in explicit non-linear calibration, a new implicit non-linear camera calibration method based on Particle Swarm Optimization (PSO) and Least Square Support Vector Machine (LSSVM) regression was proposed. A least square support vector regression machine was built to exactly approximate to the non-linear imaging relationship between image points and corresponding 3D world coordinates. And PSO algorithm was used to search the optimum parameters of the LSSVM regression model to improve the convergence speed and generalization ability. The calibration results of circular template from standard BP neural network, genetic algorithm, LSSVM and particle swarm optimized LSSVM regression, were compared. The comparison analysis indicates that the proposed LSSVM regression method based on PSO has advantages such as higher accuracy, faster convergence speed and better generalization ability..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 47 (2010)
Flatness Measurement of Large Annular Planes Based on Three-point Method
DAI Xiao-lei, CAO Xue-dong, YANG Wen-zhi, and WU Shi-bin
A method of flatness measurement of large annular planes was designed based on three-point method. By measuring the local curvature of the annular, the overall curve was connected and the flatness measurement of the whole annular was obtained. The measuring principle of three-point method was introduced, as well as theA method of flatness measurement of large annular planes was designed based on three-point method. By measuring the local curvature of the annular, the overall curve was connected and the flatness measurement of the whole annular was obtained. The measuring principle of three-point method was introduced, as well as the application of three-point method on measurement of large annular planes. The factors of zero error which impact the measurement result were analyzed. Experiments show that the method could solve the problem of flatness measurement of large annular flat parts..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 52 (2010)
Wavelength Selection Algorithm Based on the PCA from Light Extinction Measurement
TANG Hong, ZHENG Wen-bin, and LI Xian-xia
The extinction spectrums of particle system contain some information about the particle size and refractive index with total light scattering particle sizing method. In the visible and visible-infrared region, the principal component transform was performed for the extinction spectrums, the first-order differential extThe extinction spectrums of particle system contain some information about the particle size and refractive index with total light scattering particle sizing method. In the visible and visible-infrared region, the principal component transform was performed for the extinction spectrums, the first-order differential extinction spectrums and the second-order differential extinction spectrums of monomodal R-R particle system. After analysis and comparison with the Principal Component Analysis (PCA) method, a selection algorithm for the characteristic wavelengths based on the PCA was proposed. This algorithm uses the principal component transform to dispose the first-order differential extinction spectrums firstly, and then regards the contribution rate of the principal component to the first-order differential extinction spectrums at each wavelength as the main criterion by which characteristic wavelengths can be selected. Meanwhile, the boundary wavelengths in the spectrum region are also selected as the characteristic wavelengths. This selection method ensures that the extinction values of selected characteristic wavelengths contain most information about the particle size distribution. The numerical simulation experiments on the monomodal and biomodal R-R distributions were performed in the independent model, which illustrated the validity and feasibility of the selection method based on the PCA..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 56 (2010)
A New Method of Verticality Adjusting Between Optical Axis and Object Surface of Embedded Machine Vision Controller
ZHAO Jing-jing, BAI Rui-lin, LI Du, MENG Wei, and WEN Zhen-shi
To improve the accuracy of two-dimensional vision measurement, a new area method of verticality adjusting between optical axis and object surface of Embedded machine vision controller is proposed. The method based on 3-D imaging principle of cameras and image processing, uses Harris corner detector and spatial-moment tTo improve the accuracy of two-dimensional vision measurement, a new area method of verticality adjusting between optical axis and object surface of Embedded machine vision controller is proposed. The method based on 3-D imaging principle of cameras and image processing, uses Harris corner detector and spatial-moment to detect subpixel feature point, and adopts Heron Formula to calculate the special area. Then, according to the variable area rule of the relative tilted between camera lens and measured objects, the method can accurately judge the verticality between optical axis and object surface. Experiments demonstrate that the advantages of the proposed method are simple operation, stability and practicability. The measurement precision could be greatly improved by adjusting. The adjusting method has been applied in the industrial field of Embedded machine vision..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 63 (2010)
A Novel Code Design and Performance Analysis of Two-dimensional Optical Orthogonal Codes
CHEN Zhi-wen, JI Jian-hua, and ZHUANG Song-lin
Based on One-coincidence Sequence (OCS), a new two-dimensional optical orthogonal code named EQC/OCS is constructed. EQC/OCS uses Extended Quadratic Congruencies (EQC) for time spreading and OCS for wavelength hopping. Compared with EQC/PC, the number of wavelengths for EQC/OCS is not limited to a prime number. EQC/OCSBased on One-coincidence Sequence (OCS), a new two-dimensional optical orthogonal code named EQC/OCS is constructed. EQC/OCS uses Extended Quadratic Congruencies (EQC) for time spreading and OCS for wavelength hopping. Compared with EQC/PC, the number of wavelengths for EQC/OCS is not limited to a prime number. EQC/OCS can be constructed flexibly, and also can use available wavelengths effectively. When the number of available wavelengths is not a prime number, EQC/OCS has larger code cardinality of two-dimensional Optical Code Division Multiple Access (OCDMA) than that of EQC/PC under the same code length and code weight. On the other hand, compared with EQC/PC, EQC/OCS has the same performance of autocorrelation and cross-correlation..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 70 (2010)
Error Performance for Pulse Position Modulation under Turbulence Based on Maximum-likelihood Detection
HU Hao, WANG Hong-xing, XU Jian-wu, and LIU Min
Atmospheric turbulence can greatly degrade the performance of Free Space Optical (FSO) Communication system. With Gauss channel model and threshold detection, studies about Pulse Position Modulation (PPM) under turbulence have limitation in describing its characteristic. Mathematical calculation expressions about SymboAtmospheric turbulence can greatly degrade the performance of Free Space Optical (FSO) Communication system. With Gauss channel model and threshold detection, studies about Pulse Position Modulation (PPM) under turbulence have limitation in describing its characteristic. Mathematical calculation expressions about Symbol Error Rate (SER) and Bit Error Rate (BER) of PPM under turbulence channel based on Maximum-likelihood Detection (MLD) are deduced. Monte Carlo methods verify the presented theoretic calculation models. Simulations show that, PPM based on MLD will present better performance, which is also easily influenced by turbulence. The PPM receiver requires average received Signal Noise Ratio (SNR) gain not less than 0.67 dB when the modulation level is increased one level with BER 10-6 in weak turbulence atmosphere environment. For fixed peak power PPM system, synthesized devices capability and communication conditions, proper compromise should be made between the error performance and the power efficiency..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 74 (2010)
Disturbance Induced by Diffraction Effect of Microlens Array
ZHANG Wei-guo, DONG Xiao-chun, GAO Hong-tao, DENG Qi-ling, WU Shi-bin, and DU Chun-lei
Factors affecting diffraction of microlens array are analyzed, distribution expression of optical field intensity is deducted on the focal plane of microlens, and the physical explanation about Fresnel number used for evaluating diffraction effect is given. Moreover, simulation of microlens array is carried out by ZEMAFactors affecting diffraction of microlens array are analyzed, distribution expression of optical field intensity is deducted on the focal plane of microlens, and the physical explanation about Fresnel number used for evaluating diffraction effect is given. Moreover, simulation of microlens array is carried out by ZEMAX software, and the distribution of optical intensity on the focal plane is calculated. At last, comparing calculating results under different conditions, the rationality of Fresnel number as validation criteria of diffraction effect and the feasibility of Fresnel number used to judge disturbance among focal spots are validated at the same time..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 80 (2010)
Feasibility Analysis of EMCCDs for Space Bioluminescence Imaging
XIE Zong-bao, and ZHANG Tao
The detection of bioluminescense is widely used on the ground, while the detection of bioluminescence in space is still at the stage of detecting bright bioluminescense. With the rapid development of research in space life sciences, it will be necessary to develop a detection technology to detect weak bioluminescense. The detection of bioluminescense is widely used on the ground, while the detection of bioluminescence in space is still at the stage of detecting bright bioluminescense. With the rapid development of research in space life sciences, it will be necessary to develop a detection technology to detect weak bioluminescense. Compared with the low-light detection techniques for ground, the advantage of Electron Multiplying (EM) CCDs for space application was summed up, and a space bioluminescence imaging detection system suggestion based on EMCCDs was proposed. Analyzed the acquisition of weak signal and the Signal-noise Ratio (SNR) of the system from target brightness, illumination on the photosensitive area and the refrigeration of the detector, demonstrates the feasibility and capability of the space bioluminescence imaging detecting system based on EMCCDs..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 85 (2010)
Thermodynamics Finite Element Analysis of X/EUV Transmission Grating in Terrestrial Space
SONG Xi, ZHU Xiao-li, WEI Fei, XIE Chang-qing, XIE Er-qing, and LIU Ming
In order to meet the requirement of Extreme Ultraviolet (EUV) transmission grating spectrometer in terrestrial space, thermal and mechanical properties of 2000 l/mm X/EUV transmission grating was investigated by means of simulation method. The mechanistic model was established and its thermal and coupling properties weIn order to meet the requirement of Extreme Ultraviolet (EUV) transmission grating spectrometer in terrestrial space, thermal and mechanical properties of 2000 l/mm X/EUV transmission grating was investigated by means of simulation method. The mechanistic model was established and its thermal and coupling properties were simulated using the method of finite element analysis. Moreover, the distributions of thermal field and thermal deformation were obtained based on transmission grating consisting of different materials with different thermal expansion coefficients. The results are shown that the surface deformation of transmission grating is 0.56 μm as well as the longitudinal deformation value is 71.5 nm (average value). Due to thermal deformation, the diffraction efficiency and precision of spectrograph decline. In terms of simulation results, the package and structure of grating were optimized for applications in solar EUV radiation spectroscopies..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 91 (2010)
Shape-based Image Retrieval Using Krawtchouk Moment Invariants
WU Yi-quan, WU Yan-yan, and TANG Yan-liang
One major difficulty in the shape-based image retrieval area is how to keep good results after translation, rotation and scaling of the image. A novel method based on Krawtchouk moment invariants is proposed for shape-based image retrieval. Firstly, the image was transformed into gray image. Then, the low-order momentsOne major difficulty in the shape-based image retrieval area is how to keep good results after translation, rotation and scaling of the image. A novel method based on Krawtchouk moment invariants is proposed for shape-based image retrieval. Firstly, the image was transformed into gray image. Then, the low-order moments of the image were extracted. Finally, 16 low-order moment invariants were selected as image feature vectors. The similarity distance measure between feature vectors adopted Euclidean distance function. According to the similarity degree, similar images were retrieved and image retrieval was completed once. Experimental results were given. A comparison was made between the proposed method and the image retrieval method using geometric moment invariants or Zernike moment invariants. The experimental results show that the proposed method is more effective in image retrieval and improves its accuracy. Compared with above-mentioned two methods, the recall increases by 21.52% and 7.6%, respectively, while the precision increases by 16.25% and 6.25%, respectively. So the proposed method is more suitable for shape-based image retrieval..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 97 (2010)
A New Algorithm Based on Graph Cuts for SAR Image Segmentation
CHEN Hua-jie, WU Xiang-wei, and XUE An-ke
Alpha-expansion algorithm based on Graph Cuts is a useful method for minimizing energy function established by Markov Random Field model of image segmentation. However, the number of edge of the graph constructed by the algorithm is large, so the speed is rather slow. In order to reduce the complexity of the alpha-expaAlpha-expansion algorithm based on Graph Cuts is a useful method for minimizing energy function established by Markov Random Field model of image segmentation. However, the number of edge of the graph constructed by the algorithm is large, so the speed is rather slow. In order to reduce the complexity of the alpha-expansion algorithm, the relationship between the pixels labeled alpha and pixels labeled non-alpha was only considered and the relationship between the pixels labeled non-alpha was omitted. This idea avoided adding auxiliary nodes which were one of main factor to affect the efficiency of the alpha-expansion algorithm. Since the constraints on the relationship between pixels set labeled different non-alpha was loosed，it was easier for the new algorithm to escape some local minimum of energy function so as to gain more optimal segmentation results. In experiments, compared with the standard algorithms based on Graph cuts, the algorithm had the better performance in the running time and the minimum energy..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 104 (2010)
Image Threshold Segmentation Based on Tsallis Generalized Divergence
NIE Fang-yan, GAO Chao, and GUO Yong-cai
In order to obtain the optimal threshold for automatic image segmentation efficiently, a novel image thresholding method is proposed based on the conception of Tsallis generalized divergence. First, the original formula of Tsallis generalized divergence was simplified, and then the symmetrical version was constructed. In order to obtain the optimal threshold for automatic image segmentation efficiently, a novel image thresholding method is proposed based on the conception of Tsallis generalized divergence. First, the original formula of Tsallis generalized divergence was simplified, and then the symmetrical version was constructed. Subsequently, the divergence sum of the foreground and background between original and thresholded image was set up based on the symmetric equation. Finally, the sum formula was minimized to obtain the optimal threshold. The experimental results show that the proposed method is feasible and has better adaptability on complicated images. So, it is an available threshold selection method..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 110 (2010)
An Efficient Image Denoising Algorithm
XIAO Su, HAN Guo-qiang, WO Yan, and YAO Hao-wei
An efficient algorithm was presented to solve the problems of the speed and the staircase effect in the image denoising. In the Bayesian framework, firstly, the harmonic model was introduced as the prior model of the original image, and the Gamma distribution was supposed to be the prior distribution model of the unknoAn efficient algorithm was presented to solve the problems of the speed and the staircase effect in the image denoising. In the Bayesian framework, firstly, the harmonic model was introduced as the prior model of the original image, and the Gamma distribution was supposed to be the prior distribution model of the unknown parameters. Secondly, the maximum posteriori probability was deduced using the variational method, based on which the original image and the unknown parameters were estimated simultaneously to remove the noise in the observed image. The experimental results show the efficiency of the proposed algorithm. Furthermore, compared with other similar algorithms, the proposed algorithm shows the competitive performance on the speed without bringing the staircase effect to the denoised images..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 116 (2010)
A New Kind of Sun Sensor
WEI Zhi-jun, LIU Xiao-jun, and Lü Zheng-xin
Sun Sensor is a kind of popular photoelectric sensors in satellite attitude control system. It is very important to have a large field of view for the sun sensor during the course of the sun acquisition of the satellite working in the emergence mode. A ladder-shaped narrow slit sun sensor is presented, which has a verySun Sensor is a kind of popular photoelectric sensors in satellite attitude control system. It is very important to have a large field of view for the sun sensor during the course of the sun acquisition of the satellite working in the emergence mode. A ladder-shaped narrow slit sun sensor is presented, which has a very large field of view (157°) and is suitable for the application with the large attitude angle (≤175°). The design of ladder-shaped narrow slit can decrease the sensor's output pulse widths which vary largely with the attitude angle, and be convenient for the correlative circuit design. The onboard experiment validates the practicability of the presented sun sensor..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 123 (2010)
A New Type of High-speed Automatic Focusing System
FAN Fu-ming, CHENG Liang-lun, WANG Xiao-fen, and PAN Jian-hua
In order to meet the requirements of fast autofocus based on machine vision in industrial inspection systems, a new type of laser-based and high-speed embedded autofocus system is put forward. The design combines the characteristics of laser and visible light without affecting each other in the same optical path and thIn order to meet the requirements of fast autofocus based on machine vision in industrial inspection systems, a new type of laser-based and high-speed embedded autofocus system is put forward. The design combines the characteristics of laser and visible light without affecting each other in the same optical path and the capabilities of Digital Signal Processing (DSP) high-speed image processing, and controls motion actuator to achieve fast and stable focusing of microscope in the industrial inspection systems by inspecting the laser facula information reflected back by optical path designed specially. Moreover, the design improves traditional method defects of slow accuracy and speed in TFT-LCD optical inspection system, such as based on the passive image processing and active range auto-focus measurement. Test results show that the new focusing system greatly shortens the focusing time, increases the control precision of the focusing system, and meets practical application requirements in the industrial optical inspection systems..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 127 (2010)
Accuracy Analysis and Optimization Design of Constant-diameter Conjugate Focusing Cam
HUI Shou-wen, YUAN Guo-qin, DING Ya-lin, LI Yan-wei, LIU Zhe-hua, and CHEN Wei
In order to ensure the imaging quality and modulate the focusing plane, a focusing mechanism based on a constant-diameter conjugate cam is designed. To improve focusing accuracy, factors affecting the accuracy of cam are studied. The influences of the roller radial runout, cam machining error and the base circle radiusIn order to ensure the imaging quality and modulate the focusing plane, a focusing mechanism based on a constant-diameter conjugate cam is designed. To improve focusing accuracy, factors affecting the accuracy of cam are studied. The influences of the roller radial runout, cam machining error and the base circle radius on focusing accuracy are analyzed. Then, a method to guarantee the cam diameter constant and remove return stroke error is studied by using least-squares method. The analysis results indicate that the focusing accuracy can reach ± 4.7 μm, and the return stroke error can reach 4.8 μm. The functioning of institutions is stable and reliable..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 133 (2010)
The Experimental Study of Binocular Optical See-through Head-mounted Display
GAO Wei-qing, ZHOU Shi-e, and Lü Guo-qiang
The binocular see-through optical Head-mounted Display (HMD) is developed by using discrete elements，and the key problems in the HMD are researched. Using polarization beam splitter as combiner, it is found that the brightness of HMD and outside environment has cosine variation with the polarizer azimuth through theoreThe binocular see-through optical Head-mounted Display (HMD) is developed by using discrete elements，and the key problems in the HMD are researched. Using polarization beam splitter as combiner, it is found that the brightness of HMD and outside environment has cosine variation with the polarizer azimuth through theoretical analysis. Then, the image of HMD can mix together with outside environment excellently by adjusting the azimuth angle of polarizer. The variations of HMD vision effect which change with the rotation of polarizer are investigated, and the results indicate that the effect is optimal when the binocular overlapped range is 33~50% of the monocular field of view. At last the stereoscopic display of HMD is realized by the stereo image pairs which are made according to the parallax theory..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 139 (2010)
Information Hiding Algorithm for H.264/AVC Based on Encoding Mode
WANG Rang-ding, ZHU Hong-liu, and XU Da-wen
A scheme of information hiding for H.264/AVC based on encoding mode is proposed. Secret information is embedded in I-frame, P-frame and B-frame through adjustment of the encoding mode of given macroblocks. For the macroblocks provided with the encoding mode of intra 4×4, secret data is embedded by modulating the eA scheme of information hiding for H.264/AVC based on encoding mode is proposed. Secret information is embedded in I-frame, P-frame and B-frame through adjustment of the encoding mode of given macroblocks. For the macroblocks provided with the encoding mode of intra 4×4, secret data is embedded by modulating the encoding mode of some 4×4 block. For other macroblocks in P-frame and B-frame, the hiding of information is implemented by modifying the encoding mode of macroblock. After the modulation of mode, an optimized processing for the macroblock is carried out to improve the coding efficiency. By introducing the rate-distortion cost during the process of mode modulating, the proposed algorithm achieves a better balance of rate-distortion. Meanwhile, it has less influence on the quality of video and the bit-rate of video. This scheme could detect the secret information rapidly, which meets the requirement of the real-time processing of video. Experimental results also demonstrate that it is an extremely effective scheme..
Opto-Electronic Engineering
- Publication Date: Oct. 09, 2021
- Vol. 37, Issue 5, 144 (2010)
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