Journals >Opto-Electronic Engineering
Contents
2011
Volume: 38 Issue 11
27 Article(s)
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Research Article
Analysis of Scale Factor Stability Based on λ/4 Waveplate
LI Xu-you, WEI Yi-tao, HONG Wei, HE Zhou, and HAO Jin-hui
For the problem of small waveplate’s error tolerance in practical applications, which leads to instability of scale factor, a novel way of compensating scale factor is presented, which increases the error tolerances, thus efficiently increases stability of scale factor of fiber optic current transducer. Through theoretFor the problem of small waveplate’s error tolerance in practical applications, which leads to instability of scale factor, a novel way of compensating scale factor is presented, which increases the error tolerances, thus efficiently increases stability of scale factor of fiber optic current transducer. Through theoretical analysis, the paper presents the theoretical model of λ/4 waveplate, and analyzes the accuracies of 0.2% and 0.01% of scale factor, which requires the tolerances of orientation error and retardation error. After peak -divide way applied to compensate, the results show that, compared with uncompensated system, for the accuracy of 0.2％ and 0.01％ of scale factor, the tolerances of orientation error and retardation error increase about 4.7 times and 11 times respectively. Thus, stability of scale factor also increases 4.7 times and 11 times respectively for the two different accuracies, and those also show that the higher accuracy, the more obvious compensation effect. Applied peak-divide way efficiently decreases the instability of scale factor which brings in measured error..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 1 (2011)
Temperature Dependence of Brillouin Scattering Spectrum for High Nonlinear Photonic Crystal Fiber
HUANG Min-shuang, and HUANG Jun-fen
The theory that optical amplification of stimulated Brillouin scattering can be generated through interaction of two counter propagating laser beams in photonic crystal fiber is used. Varieties of Brillouin scattering spectrum and Brillouin frequency shift along with temperature are studied via experiments. The experimThe theory that optical amplification of stimulated Brillouin scattering can be generated through interaction of two counter propagating laser beams in photonic crystal fiber is used. Varieties of Brillouin scattering spectrum and Brillouin frequency shift along with temperature are studied via experiments. The experiment results show that the photonic crystal fiber has a frequency shift of 9.795 GHz, a Brillouin spectrum width of 19 MHz and a frequency shift temperature coefficient of 1.33℃/MHz when the incident beam has a wavelength of 1 548 nm at temperature 25℃. Brillouin scattering spectrums of a high nonlinear photonic crystal fiber and a standard single-mode fiber are measured and discussed, and results are presented that the photonic crystal fiber has a narrower Brillouin scattering bandwidth and a stronger temperature dependence corresponding to the standard single-mode fiber, and the photonic crystal fiber can turn into a novel fiber sensing component for a distributed fiber Brillouin sensor..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 6 (2011)
Influence of Reducing Peak-to-average Power Ratio of OFDM Signals on Performance of Direct-detection Optical OFDM System
WANG Zhong-peng, XIAO Jiang-nan, LI Fan, and CHEN Lin
The high peak-to-average power ratio is the main disadvantage of Orthogonal Frequency-division Multiplexing (OFDM) communication systems, so there is the same problem in optical OFDM systems. A joint reduction Peak-to-average Power Ratio (PAPR) scheme, based on combining Hadamard transform with clipping, is successfullThe high peak-to-average power ratio is the main disadvantage of Orthogonal Frequency-division Multiplexing (OFDM) communication systems, so there is the same problem in optical OFDM systems. A joint reduction Peak-to-average Power Ratio (PAPR) scheme, based on combining Hadamard transform with clipping, is successfully applied to an experimental system of direct-detection optical OFDM signal transmission over fiber. The performance of bit error rate of system is mainly researched. In this experiment, the 2.5 Gb/s QPSK optical OFDM signal with Hadamard transformation is generated and transmitted over single mode fiber. The experiment results show that the proposed scheme can reduce PAPR almost 3.2 dB. Meantime, the received sensitivity is improved 3dB with 100 km fiber transmission compared to that of ordinary optical direct detection OFDM system..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 11 (2011)
High-precision Linear Fitting of Edges in Alignment of Fiber and Waveguide
YANG Bo, and DUAN Ji-an
High-precision edge detection of fiber and waveguide chip is an important basis for the position and posture adjustment of waveguide alignment. Considering that the conventional edge line detection algorithms can not meet the need of high-precision detection of waveguide devices edge, a new fitting method of linear appHigh-precision edge detection of fiber and waveguide chip is an important basis for the position and posture adjustment of waveguide alignment. Considering that the conventional edge line detection algorithms can not meet the need of high-precision detection of waveguide devices edge, a new fitting method of linear approximation based on the idea of least squares was introduced, where the coefficient converged to zero. First of all, factor analysis of relationship between the fitting function coefficient and the linear correlation coefficient was undertaken, and a assessment model of non-random error was established. Then, under the hypothesis that non-random errors was assumed to be large enough and was limited in small enough regions, a subspace, which belonged to a general sample space and only have random errors, was proved to have less variance than that of the general sample space. Finally, based on the relationship of residuals of the linear approximation, a new fitting method was proposed. The experiment results showed that the new algorithm accurately detected the linear edge which was damaged and the angle error was less than 0.01 degree. Therefore, the new method has some excellent characteristics, e.g. high precision, anti-impact ability on errors, and fast convergence of fitting coefficients, and it can meet the need of high-precision fields, such as auto micro-electronics and opto-electronics packaging..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 16 (2011)
New Method for Cutting Circle and Arc
QIN Hua, and SUN Cun-zhi
In practical applications of laser cutting, the quality of the cutting surfaces is the critical factor. Recently, methods for studying the influence on quality of the main process variables have been developed, which seek to improve quality rather than explain the cutting mechanism. In the present study, a new method fIn practical applications of laser cutting, the quality of the cutting surfaces is the critical factor. Recently, methods for studying the influence on quality of the main process variables have been developed, which seek to improve quality rather than explain the cutting mechanism. In the present study, a new method for circle and arc cutting is presented based on optical characteristic of a glass cone. In a laser cutting system, we use a glass cone to replace beam-focusing optics to direct the beam to the workpiece, and equipment for moving either the laser beam or the workpiece, or both, to obtain the circle or arc cutting pattern. Theoretical analysis and simulation studies of a glass cone show that the method solves an issue that the focal depth and focal spot can not be optimized, ensures the strict vertical cutting surface and the high cutting quality, and greatly reduces the workload caused by the motion of the beam or the workpiece..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 23 (2011)
Analysis of Beam Quality for Spectral Beam Combining System with Microlens Array
WU Zhuo-liang, ZHAO Shang-hong, CHU Xing-chun, ZHANG Xi, and LI Yun-xia
Aiming at the problem of beam quality evaluation for external cavity-based spectral beam combining system with microlens array, the theoretical model for evaluating the beam quality of beam-combined laser is established. According to the model, the influences of relevant system parameters on beam quality are numericallAiming at the problem of beam quality evaluation for external cavity-based spectral beam combining system with microlens array, the theoretical model for evaluating the beam quality of beam-combined laser is established. According to the model, the influences of relevant system parameters on beam quality are numerically analyzed in detail. The simulation results show that the beam quality is mainly influenced by the defocus value, the focal length of microlens and the mode field radius, while the influences of the array width are little. With the array width changing from zero to 10mm, the beam quality factors in x and y directions are preserved near 1.225 and 1 respectively. Compared with the traditional spectral beam combining system, the incorporation of microlens array effectively improves the beam quality of output laser. In order to keep the beam quality factor in x direction smaller than 1.3, the defocus value ought to be restricted in a range of -0.017~0.017 mm. For spectral beam combining system with large mode area double-clad fibers, the beam quality can be improved through utilizing microlens array with longer focal length..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 29 (2011)
Experimental Study of Detecting “Cat-eye” Target Based on CCD
ZHOU Bin, LIU Bing-qi, ZHANG Yu, and WU Dong-sheng
The most distinguished advantage of an active laser detection system based on CCD detection device is the capability of acquiring the straightforward vision of “cat-eye” targets. The active laser detection theory based on “cat-eye” effect was discussed according to the model for echo power ratio of “cat-eye” target andThe most distinguished advantage of an active laser detection system based on CCD detection device is the capability of acquiring the straightforward vision of “cat-eye” targets. The active laser detection theory based on “cat-eye” effect was discussed according to the model for echo power ratio of “cat-eye” target and diffuse reflection target. The key components of this detection system were described and the wavelength matching problem of CCD device and laser source was analyzed. The detection experiments were made by using typical “cat-eye” target at different distances, such as 300 m and 2 500 m. The experimental result shows that the “cat-eye” target can be easily found from background at a certain detection distance, so the validity of the active laser detection system is proved..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 35 (2011)
Imaging Verification System of Fourier Telescopy in Laboratory
DONG Hong-zhou, WU Jian, LIU Yi, and ZHANG Yan
The imaging fundamental principle of Fourier telescopy is introduced. In order to verify the validity of the technology, an imaging verification system of four beams had been completed in laboratory. The control, detection and signal processing software were designed based on LabVIEW. Two-dimensional spectra of objectiThe imaging fundamental principle of Fourier telescopy is introduced. In order to verify the validity of the technology, an imaging verification system of four beams had been completed in laboratory. The control, detection and signal processing software were designed based on LabVIEW. Two-dimensional spectra of objection were extracted by straight line fringe. With the phase closure technology, the phase factor being independent of image is eliminated and the reconstruction images of the object were obtained. Finally, the factors affecting the imaging quality are analyzed..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 40 (2011)
Thermal Control Method and Experimental Study of High-speed TDI CCD Focal Plane Used in Space-based Telescope
WANG Dong, YAN Yong, and JIN Guang
Excessively high temperature can greatly increase the thermal noise of TDI CCD, which will reduce the camera's image quality significantly, so thermal control methods must be taken to decrease the temperature of TDI CCD focal plane. One high-speed TDI CCD circuit, which had a difficulty in heat dissipation because Excessively high temperature can greatly increase the thermal noise of TDI CCD, which will reduce the camera's image quality significantly, so thermal control methods must be taken to decrease the temperature of TDI CCD focal plane. One high-speed TDI CCD circuit, which had a difficulty in heat dissipation because of high power density, was discussed in detail. Limited by the mass and power consumption, traditional radiant cooling panel method couldn’t be used. Based on the stronger temperature adaptability, the method of reducing the temperature of camera and using the large heat capacity character of electricity box was taken on the focal plane. Through the camera’s thermal balance test, thermal control effect of the method was verified, and the optimization scheme was presented. The results show that, under high temperature cases, the maximum temperature of TDI CCD is 30℃，about 10℃ lower than nothing thermal control method was taken, and the method can satisfy TDI CCD’s requirements well..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 45 (2011)
Remote Sensing Image Change Detection Based on Greedy EM Algorithm for HMRF
NIU Peng-hui, LI Wei-hua, and LI Xiao-chun
A remote sensing image change detection approach based on greedy Expectation Maximization (EM) algorithm for Hidden Markov Random Field (HMRF) is proposed. The difference image is constructed by Principal Component Analysis (PCA) and subtraction operation. Firstly, the HMRF model is applied to characterize the contextuA remote sensing image change detection approach based on greedy Expectation Maximization (EM) algorithm for Hidden Markov Random Field (HMRF) is proposed. The difference image is constructed by Principal Component Analysis (PCA) and subtraction operation. Firstly, the HMRF model is applied to characterize the contexture-dependent information, and the energy function of system is defined. Secondly, the greedy EM algorithm is used to overcome the disadvantage of the standard EM algorithm that assumed the number of the mixture components is a known priori, the performance of the overall parameter estimation process depends on the given good initial settings excessively, and the estimated parameter can be resulted from some local optimum points. The distribution model structure and parameters are learned accurately to find the best fit of the given data. Finally, the changed area is obtained by using Iterated Conditional Modes (ICM) to optimize the energy function. Experiments show that the proposed method has virtues of preserving structural change and filtering noises..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 50 (2011)
Combined Space Objects’ Orbit Determination Based on Space/Ground-based Tracking Telemetry and Command Technology
ZHAO Bo, ZHOU Qing-yong, ZHANG Wang, and FU Jing-yang
The Space-Based Space Surveillance (SBSS) system is an important way and the development tendency of accepting state information of space objects. However，only utilizing the measure information between the satellites would produce the deficient–rank phenomena in the process of orbit determination of space objects. The The Space-Based Space Surveillance (SBSS) system is an important way and the development tendency of accepting state information of space objects. However，only utilizing the measure information between the satellites would produce the deficient–rank phenomena in the process of orbit determination of space objects. The essence of deficient-rank problem in the autonomous orbit determination was discussed. The problem can be eliminated by the combined orbit determination strategy based on space/ground-based tracking telemetry and command technology. The tracking network was made up of 4 high-orbit surveillance platforms and 2 ground surveillance stations. The orbit determination function of the system for the space objects was simulated. Simulation experiment shows the orbit determination precision for three kinds of space objects based on the combined orbit determination strategy reaches kilometer level..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 57 (2011)
Visual Measurement Methods on 100 Meters Distance Coordinates
LI Xiao-feng, ZHAO Yu, LI Wei-min, JIN Jing, and ZHANG Yu
In order to achieve the 100 meters far away object measurement of large radio astronomical telescope, visual measurement system has been established. The arithmetic of object detection and stability of the measurement system has been researched. First, the CCD camera obtains the image information of the reflected targeIn order to achieve the 100 meters far away object measurement of large radio astronomical telescope, visual measurement system has been established. The arithmetic of object detection and stability of the measurement system has been researched. First, the CCD camera obtains the image information of the reflected target 100 meters far away. The target image is interpolated by using spline function and the edge information of the target is detected with Canny algorithm. Then, the position of target is measured by adopting ellipse fitting algorithm. Consequently, the image plane coordinates of the target is acquired. The validity of the detection algorithm is appraised by adopting a plane calibration jig. Finally, in the outdoor conditions, the stability of the target measurement is researched at day and night. Experiment results show that the target detection algorithm has the measurement precision of sub-pixel and the stability precision of 100 meters distance target measurement is 0.08 pixels. It can atisfy the 100 meters distance coordinates measurement of large radio astronomical telescope and has better anti-jamming capability..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 63 (2011)
Fine Patterning of Optical Waveguide Films Fabricated by Photosensitive Sol-gel Process
XU Zhen-wu, XU Jian, XU Qing-bo, and DONG Jian-feng
Organic-inorganic hybrid Photosensitive SiO2-TiO2 materials were synthesized by a sol-gel process. The hybrid films were deposited on silica glass substrates and silicon wafers by spin-coating. After the process of prebaking, UV-light exposure and postbaking, the films with the same patterning of mask were obtained. ThOrganic-inorganic hybrid Photosensitive SiO2-TiO2 materials were synthesized by a sol-gel process. The hybrid films were deposited on silica glass substrates and silicon wafers by spin-coating. After the process of prebaking, UV-light exposure and postbaking, the films with the same patterning of mask were obtained. The Optical transmittance and absorption of hybrid films were measured with a ultraviolet-visible-near infrared spectrometer. Their infrared spectra of films at different UV irradiation time were measured with Fourier infrared spectrometer. The surface micro-structures prepared were observed by optical microscopy with a high-resolution CCD camera and Scanning Electron Microscope (SEM). The results show that light transmittances of the hybrid films are nearly 90% in the visible and near infrared range and UV curing has an effect of producing the photopolymerization of methacrylate species. Being prebaked at 80℃ and irradiated with UV light for 15 minutes are very crucial to get clear and precise patterns..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 68 (2011)
Analysis of Film Thickness Uniformity for Large Aperture Coater of 3.6 m in Diameter
AI Wan-jun, and XIONG Sheng-ming
The theoretical calculation models for the rotating flat and spherical fixture configurations have been established respectively and the thickness uniformity of 2.6 m substrates in large aperture coater of 3.6 m in diameter have been studied. In order to improve the thickness uniformity, two sources and three sources hThe theoretical calculation models for the rotating flat and spherical fixture configurations have been established respectively and the thickness uniformity of 2.6 m substrates in large aperture coater of 3.6 m in diameter have been studied. In order to improve the thickness uniformity, two sources and three sources have been employed. The thickness nonuniformity was acquired via the optimization calculations using the theory models. The optimal geometric configurations were obtained for two sources with the two rotating fixture configurations respectively, and the corresponding minima of thickness nonuniformity were 7.62% and 5.58%, respectively. For three sources, in the same way, the corresponding minima of thickness nonuniformity were 5.79% and 3.48%, respectively. It is found that compared with two sources, three sources can improve the thickness distribution to a great extent. Moreover, the thickness distribution obtained with the rotating spherical fixture configuration performs well as a whole..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 73 (2011)
Adaptive Wiener Filtering Noise Reduction in Infrared Images
BAI Jun-qi, ZHAO Chun-guang, WANG Shou-feng, and SUN Ning
The Signal-to-Noise Ratio (SNR) and contrast are low in infrared image, which is serious in low target radiation, long detecting distance and bad weather. For enhancing the SNR of infrared image, an adaptive Wiener filtering noise reduction algorithm is proposed. In this algorithm, the technical bottleneck that power sThe Signal-to-Noise Ratio (SNR) and contrast are low in infrared image, which is serious in low target radiation, long detecting distance and bad weather. For enhancing the SNR of infrared image, an adaptive Wiener filtering noise reduction algorithm is proposed. In this algorithm, the technical bottleneck that power spectrums of undegraded image and noise need be known in traditional Wiener filtering is broken. A neighborhood estimation criterion of noise variance of smoothness region is proposed, and the noise adaptive reduction of infrared image is achieved. Experimental results show the proposed algorithm can adjust filtering parameters adaptively, remove the noise, and in the mean time effectively preserve the information of edge and detail, which can be applied to infrared real-time imaging system..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 79 (2011)
A Multi-resolution Image Fusion Algorithm without Reconstruction
WANG Hong-mei, HAN Zhi-guo, and CHEN Li-hua
A novel multi-focus image fusion algorithm is proposed on the basis of stationary wavelet transform without reconstruction. The original images to be fused are firstly decomposed by stationary wavelet transform. The low-frequency coefficients and high-frequency coefficients can be obtained. The clarity of low-frequencyA novel multi-focus image fusion algorithm is proposed on the basis of stationary wavelet transform without reconstruction. The original images to be fused are firstly decomposed by stationary wavelet transform. The low-frequency coefficients and high-frequency coefficients can be obtained. The clarity of low-frequency coefficients is estimated by the energy of Laplacian and the decision map can be acquired by comparing the energy of Laplacian. For the high-frequency coefficients at different resolution and different direction, the absolute value of these coefficients are summed firstly, and then the local region energy is used as the feature to get the high-frequency decision map. The fused image can be obtained by combining the low-frequency decision map and high-frequency decision map. The simulated results demonstrate that the proposed algorithm can get clearer image when compared with the average method, the traditional wavelet-based algorithm and some modified algorithm. The objective evaluation indices value, such as Shannon, average gradient, space frequency, standard deviation and mutual information, are improved compared with the average method and the traditional wavelet-based algorithm. Especially, the mutual information value computed by our algorithm is 2.4 times compared with the algorithm of Ref [3]. Subjective observation and objective evaluation suggest that our algorithm is effective for multi-focus image fusion..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 86 (2011)
An Improved Information Hiding Algorithm with Prediction Mode Modulating for H.264/AVC
XU Da-wen, and WANG Rang-ding
An information hiding algorithm with prediction mode modulating for H.264/AVC is proposed. According to the luminance values of the reference pixels, the luminance blocks for information embedding are selected. The information is embedded by modulating the prediction modes of 4×4 luminance blocks. If the best modeAn information hiding algorithm with prediction mode modulating for H.264/AVC is proposed. According to the luminance values of the reference pixels, the luminance blocks for information embedding are selected. The information is embedded by modulating the prediction modes of 4×4 luminance blocks. If the best mode does not match the information bit, the prediction modes can be modulated by replacing the best mode with the substitute mode. The substitute mode is the one with the least Lagrangian cost among those having different parity with the best mode. The extraction of information can be performed directly from the encoded stream without resorting to the original video, and merely requires decoding the intra prediction mode from bit stream rather than decoding the whole video. Experimental results show that the proposed hiding scheme can effectively embed information with little bit rate increase and almost no quality degradation..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 93 (2011)
Quality Assessment Method for Asymmetric Distortion of Stereoscopic Image Based on Wavelet Image Fusion
ZHOU Wu-jie, YU Mei, LI Fu-cui, FU Song-yin, LUO Ting, and JIANG Gang-yi
Through studying visual perception of asymmetric distortion of stereoscopic image, a quality assessment method for asymmetric distortion of stereoscopic image based on Wavelet Image Fusion (WIF) is proposed. Firstly, the block disparity value is computed by fixed block marching method. Then, the original and distorted Through studying visual perception of asymmetric distortion of stereoscopic image, a quality assessment method for asymmetric distortion of stereoscopic image based on Wavelet Image Fusion (WIF) is proposed. Firstly, the block disparity value is computed by fixed block marching method. Then, the original and distorted fusion images are obtained by WIF according to original block disparity value and stereoscopic visual perception. Finally, the stereoscopic image quality is objectively assessed by calculating the distances between directional projection of original and distorted fusion images. Experimental results show that the proposed objective method achieves consistent stereoscopic image quality evaluation results with subjective assessment for various types of distortions, especially shows its effectiveness for assessing stereoscopic image with cross-distortion..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 100 (2011)
Fixed Noise Locating Algorithm Based on Quasi-Gaussian Model for Microscope Image
WANG Yi-gang, JIANG Gang-yi, YU Mei, PENG Zong-ju, FAN Sheng-li, and SHAO Feng
An adaptive algorithm based on quasi-Gaussian model is proposed for locating fixed noise in microscope image. Firstly, by considering temporal correlation of microscope image sequence, mean and variance of each color component for pixels at the same location in image sequence are computed. Secondly, the maximizing inteAn adaptive algorithm based on quasi-Gaussian model is proposed for locating fixed noise in microscope image. Firstly, by considering temporal correlation of microscope image sequence, mean and variance of each color component for pixels at the same location in image sequence are computed. Secondly, the maximizing inter-class variance (OTSU) method is used to obtain three adaptive mean thresholds of color components. Meanwhile, three adaptive variance thresholds are acquired by averaging minimum variance and maximum variance. Then, the thresholds are utilized to check each pixel in the image sequence to detect the candidates of fixed noise. After several iterations to eliminate false candidates, fixed noises are finally located. Experimental results show that the proposed algorithm can stably detect fixed noise in microscope image sequences even though the background and object luminance change a lot..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 106 (2011)
Bilateral Tensor Filter
JIN Xina, WANG Xiao-tonga, XU Xiao-gangb, and XU Guan-leia
Aiming to solve the problem that bilateral filter preserves noise boundaries which have large intensity difference as strong edges, Bilateral Tensor Filter (BTF) was presented. Based on bilateral filter, the structure preserving function was constructed self-adaptively by local structure anisotropic similarity and photAiming to solve the problem that bilateral filter preserves noise boundaries which have large intensity difference as strong edges, Bilateral Tensor Filter (BTF) was presented. Based on bilateral filter, the structure preserving function was constructed self-adaptively by local structure anisotropic similarity and photometric similarity, which filter the image along the direction of the local structure around the edge and turn into approximate isotropic around the flat area in the presence of strong noise. By substituting this structure preserving function for edge preserving function, the structure information was preserved while the noise was suppressed. Experiment results demonstrate that our bilateral tensor filtering algorithm substantially improves the quality of the filtered images and possesses a stronger edge preserving ability..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 113 (2011)
Image Denoising in Multi-wavelet Domain Based on Particle Swarm Optimization
LI Jin-xiang, LIN Jian-hui, YIN Cao-qian, and JIN Wei
An approach of image denoising in multi-wavelet domain based on particle swarm optimization was proposed. Firstly, particle swarm optimization was used to construct the adaptive pre-filters of CL multi-wavelet transform. Then noised image was decomposed by multi-wavelet transform and the coefficients were processed usiAn approach of image denoising in multi-wavelet domain based on particle swarm optimization was proposed. Firstly, particle swarm optimization was used to construct the adaptive pre-filters of CL multi-wavelet transform. Then noised image was decomposed by multi-wavelet transform and the coefficients were processed using threshold scheme according to the energy distribution of coefficients. Finally, denoised image could be obtained by inverse multi-wavelet transform. Experiments show, the proposed approach outperforms traditional wavelet denoising methods in terms of PSNR and visual effects. Moreover, the approach is beyond median filter and Wiener filter obviously..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 119 (2011)
360° Viewable Volumetric 3D Display System with Full Screen
LIU Ying, PAN Wen-ping, ZHANG Zhao-xing, LIU Yong, and CHEN Xing-hua
A volumetric display system with full helical screen is presented. When a series of helical slices of a 3D model is projected onto a rotating helical screen through a Digital Micro-mirror Device (DMD) as a fast Space Light Modulator (SLM), due to the persistence of vision, human observers are able to perceive a 360A volumetric display system with full helical screen is presented. When a series of helical slices of a 3D model is projected onto a rotating helical screen through a Digital Micro-mirror Device (DMD) as a fast Space Light Modulator (SLM), due to the persistence of vision, human observers are able to perceive a 360°viewable 3D image by fusing together the successive helical slices into a 3D image. We analyze the performance of the 3D imaging space created by a rotating helical screen, and emphasize the volexlization approach based on Enhanced Body-center Cubic (EBCC) sampling algorithm. Experimental results demonstrate that, compared with the voxelization approach based on Cartesian lattice, voxel hole avoidance and a voxel reduction of more than 30% are both achieved through utilizing EBCC sampling algorithm, and the prototype is capable of generating images with consistent brightness in a imaging space three times bigger than our former system with half screen. In the cuboid imaging space with length 400 mm, width 300 mm and height of 250 mm, 3D images can be viewed from any viewpoint without any special eyewear..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 124 (2011)
The Effect of Lattice Shapes of Thue-Morse Crystals on the Diffraction Pattern
FENG Ya-ping, ZHOU Jun, Lucia Petti, YANG Ming-yang, ZHANG Ling-fen, and MA You-qiao
According to the principle of Fourier optics, the effect of the lattice shape of two-dimensional Thue-Morse quasicrystals (2D TM QC) on the diffraction patterns is analyzed. The shapes of lattices have a considerable influence on the diffraction pattern of the lower order 2D TM QC, but do not affect that of the higher According to the principle of Fourier optics, the effect of the lattice shape of two-dimensional Thue-Morse quasicrystals (2D TM QC) on the diffraction patterns is analyzed. The shapes of lattices have a considerable influence on the diffraction pattern of the lower order 2D TM QC, but do not affect that of the higher order 2D TM QC, excepting a little change on the intensity distribution. And the above numerical results are demonstrated by the diffraction experiments of samples of 2D TM QC with the circle and square lattices, which are fabricated on the substrate of Poly Methyl Methacrylate (PMMA) by the Electron Beam Lithography (EBL). It is shown that the experimental results are consistent with the theoretic simulations very well..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 130 (2011)
Theoretical Analysis of the Complete Periphery Clamp in KDP Crystals
XIONG Zhao, JIA Kai, ZHANG Bin, CUI Kai-hong, XU Pan, and YUAN Xiao-dong
Owing to the effect of clamp and gravity on the large aperture KDP crystal, additional surface error would be introduced in the frequency conversion system. The method of complete periphery clamp in KDP crystals has been presented，and the theoretical model simulating the situation that KDP crystals vertically mount hasOwing to the effect of clamp and gravity on the large aperture KDP crystal, additional surface error would be introduced in the frequency conversion system. The method of complete periphery clamp in KDP crystals has been presented，and the theoretical model simulating the situation that KDP crystals vertically mount has been analyzed. The results show that: symmetrical sustentation and even force make the crystal surface suitable for engineering application, and the requirement of physical experiment is able to be met when the force on the 4 nails of the above profile is less than 25 N under the condition of symmetrical sustentation and even force..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 136 (2011)
Design of Fourier Transform Lens in Optical Holography
WANG Gang, SUN Jie, GUO Jun, and WANG Wen-sheng
A design of Fourier transform lens which adopt four-approximate symmetric structure was designed based on poor quality of optical holographic reconstructed image. The lens parameters were determined by the matching requirements of Electrically Addressed Liquid Crystal Displays (EALCD) and CCD. A double long-range strucA design of Fourier transform lens which adopt four-approximate symmetric structure was designed based on poor quality of optical holographic reconstructed image. The lens parameters were determined by the matching requirements of Electrically Addressed Liquid Crystal Displays (EALCD) and CCD. A double long-range structure was adopted in order to decrease total length, and optimized by ZEMAX of auto designed software. The designed result had been applied to the experiment and clear optical holographic reconstructed images were obtained. The experimental result indicates that each index of the Fourier transform lens has matched the holography system and has many advantages, such as simple and compact structure, cheap material and high-quality imaging..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 141 (2011)
Fitting of Index Homogeneity Data on the Rectangle Pupil
LIAO Zhi-yuan, XING Ting-wen, and LIU Zhi-xiang
Zernike circle polynomials are in widespread use for wavefront analysis because of their orthogonality over a circular pupil and their representation of balanced classical aberrations. Using the circle polynomials as the basis functions for their orthogonalization over rectangle pupil, we derive closed-form polynomialsZernike circle polynomials are in widespread use for wavefront analysis because of their orthogonality over a circular pupil and their representation of balanced classical aberrations. Using the circle polynomials as the basis functions for their orthogonalization over rectangle pupil, we derive closed-form polynomials that are orthonormal over it. The polynomials are unique in that they are not only orthogonal across rectangle pupils, but also represent balanced classical aberrations, just as the Zernike circle polynomials are unique in these respects for circular pupils. The polynomials may be given in terms of the circle polynomials as well as in polar or Cartesian coordinates. Using the first 15 items of the rectangle polynomials to fit the data of interferometer of rectangle windows in the least squares method, we can get the conclusion that the first 15 items of the rectangle polynomials can be fit the data very well from the result of statistical analysis..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 11, 146 (2011)
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