Journals >Opto-Electronic Engineering
Contents
2012
Volume: 39 Issue 2
28 Article(s)
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Research Article
Reflection Spectra and Delay Characteristics of the Photonic Crystal Fiber Chirped Grating
BI Wei-hong, LI Jian-ping, and QI Yue-feng
Based on the finite element method and transmission matrix method, the reflection spectrum of the grapefruit-type structure photonic crystal fiber chirped grating is analyzed theoretically. Compared with the results of simulation and experimental, it is seen that the method is feasible. The results show that the chirpeBased on the finite element method and transmission matrix method, the reflection spectrum of the grapefruit-type structure photonic crystal fiber chirped grating is analyzed theoretically. Compared with the results of simulation and experimental, it is seen that the method is feasible. The results show that the chirped grating has several reflection peaks. Moreover, the influences of the chirp coefficient and refractive indexes modulation on the resonant bandwidth and reflectivity are simulated. It is found that with the increase of the chirp coefficient and refractive indexes modulation, the reflection spectrum is changed regularly. When the chirp coefficient increases to a certain extent, the four reflection peaks can be connected together to form a large reflection bandwidth. At the same time, the delay characteristics of fundamental mode are studied. It can be seen that photonic crystal fiber chirped grating has a relatively smooth delay curve, so it can be used for dispersion compensation..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 1 (2012)
Application of Phase-shifted Long Period Grating in EDFA Gain Flattening
WANG Zhao-hui, and ZHENG Ke-rong
Based on the theoretical analysis of phase-shifted long-period grating, the transmission spectrum of phase-shifted long-period grating is studied by transfer matrix method. The impacts of magnitude of phase shift, change of average refractive index and length of grating on transmission spectrum of phase-shifted long-peBased on the theoretical analysis of phase-shifted long-period grating, the transmission spectrum of phase-shifted long-period grating is studied by transfer matrix method. The impacts of magnitude of phase shift, change of average refractive index and length of grating on transmission spectrum of phase-shifted long-period grating are discussed. According to the rules, the structure parameters of phase-shifted long-period grating are properly adjusted to make its transmission spectrum correspond with the target spectrum for flattening EDFA to some extent. Maximum fluctuation of flattened gain spectrum of EDFA does not exceed ±0.7 dB in the range of 34 nm. The gain flattening filter designed by this method only contains one device, and it has favorable market prospects due to small size and ease of manufacturing and packaging..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 7 (2012)
Application of Symmetrical Reposition Modulation in Mini-FOG
LIU Zhi-rong, JI Shi-tao, and LAN Yan
In Fiber Optic Gyroscope (FOG) system, one of the most important parts in full closed-loop control is 2π reposition modulation. Due to the increase of half voltage of miniaturized multi-functional integrated optic chip, the modulation signal in miniaturized fiber optic gyroscope can’t afford to the full range voltage oIn Fiber Optic Gyroscope (FOG) system, one of the most important parts in full closed-loop control is 2π reposition modulation. Due to the increase of half voltage of miniaturized multi-functional integrated optic chip, the modulation signal in miniaturized fiber optic gyroscope can’t afford to the full range voltage of 2π. Based on the analysis of closed-loop principle, a new method was presented, which was called symmetrical reposition modulation, and the method can be well used to achieve the reposition modulation in closed-loop control to miniaturized fiber optic gyroscope..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 12 (2012)
Effect of Dove Prism Manufacturing Errors on Coupling Loss
ZHAO Zhen, JIA Da-gong, XU Qiang, ZHANG Hong-xia, and ZHANG Yi-mo
When a parallel beam light incident to a Dove prism, the manufacturing errors of Dove prism result in the tilted or lateral displacement at the emergence surface of the Dove prism. As a result, the coupling losses of optical signals are induced in an optical rotary joint using a Dove prism. The influence of manufacturiWhen a parallel beam light incident to a Dove prism, the manufacturing errors of Dove prism result in the tilted or lateral displacement at the emergence surface of the Dove prism. As a result, the coupling losses of optical signals are induced in an optical rotary joint using a Dove prism. The influence of manufacturing errors of Dove prism on coupling loss is analyzed both in theory and simulation using the method of light ray tracing. The analytical result shows that the coupling losses due to the manufacturing errors would increase as the error in base angles and the pyramidal error increase. Afterwards, according to the theoretical results and the demands of multi-channel optical rotary joint, 5 pieces Dove prisms are designed and manufactured, and then the coupling loss is measured and corrected, which further verifies the validity of the theory..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 16 (2012)
Fabry-Perot Interferometer Sensor for High Temperature Measurement Based on Photonic Crystal Fiber
XU Lai-cai, DENG Ming, ZHU Tao, and RAO Yun-jiang
A new method of producing a fiber-optic Fabry-Perot Interferometer (FPI) for high-temperature sensing is presented. The sensor is fabricated by fusion splicing a short section of Endlessly SIngle-mode Photonic Crystal Fiber (ESM-PCF) to the cleaved end of a Single-mode Fiber (SMF) with an intentional complete collapse A new method of producing a fiber-optic Fabry-Perot Interferometer (FPI) for high-temperature sensing is presented. The sensor is fabricated by fusion splicing a short section of Endlessly SIngle-mode Photonic Crystal Fiber (ESM-PCF) to the cleaved end of a Single-mode Fiber (SMF) with an intentional complete collapse at the splice joint. Compared with the existing PCF-based FPI sensors, the FPI sensor fabricated by using the simple method have a stable sinusoidal interference fringe with higher interference light intensity. The high-temperature response of the FPI sensor was experimentally studied and the results show that the sensor allows liner and stable measurement of temperatures up to 1 100 ℃ with sensitivity of ~29.4 nm/℃, which makes it very attractive for aeronautics and metallurgy areas..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 21 (2012)
Influence of Finite Extinction Ratio of MZM on Optically Generated Millimeter-wave
YING Xiang-yue, XU Tie-feng, LIU Tai-jun, and NIE Qiu-hua
Optical generation of millimeter-wave (mm-wave) is very attractive for the applications such as radio-over-fiber for wireless communications, imaging, and radio astronomy observations. The optical generation of mm-wave signal employing Double-sideband with Carrier Suppression (DSBCS) modulation using a single-electrodeOptical generation of millimeter-wave (mm-wave) is very attractive for the applications such as radio-over-fiber for wireless communications, imaging, and radio astronomy observations. The optical generation of mm-wave signal employing Double-sideband with Carrier Suppression (DSBCS) modulation using a single-electrode Mach-Zehnder Modulator (MZM) is theoretically analyzed. The impact of the finite Extinction Ratio (ER) of MZM on the generated mm-wave signal is discussed. An experimental setup using a single-electrode MZM based on DSBCS modulation is built. A stable millimeter-wave signal tunable from 46 to 60 GHz with less than 1.5 dB power variation is obtained by tuning the electrical driving signal from 23 to 30 GHz..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 26 (2012)
An Automatic Method of Searching and Matching Sub-aperture for Shack-Hartmann Wavefront Sensor
WEI Ling, YANG Jin-sheng, SHI Guo-hua, WANG Fei, RAO Xue-jun, CAI Liu-mei, JIANG Xian-po, and ZHANG Yu-dong
An automatic method of searching and matching sub-aperture for Shack-Hartmann Wavefront Sensor (SHWFS) is introduced to enlarge the dynamic range of SHWFS while maintaining its designed accuracy. Firstly, the threshold of the image is estimated. By taking a spot of near the center of the thresholded image as the refereAn automatic method of searching and matching sub-aperture for Shack-Hartmann Wavefront Sensor (SHWFS) is introduced to enlarge the dynamic range of SHWFS while maintaining its designed accuracy. Firstly, the threshold of the image is estimated. By taking a spot of near the center of the thresholded image as the reference center, other spots are searched horizontally and vertically and combined to retrieve the whole sub-aperture distribution. Finally, the sub-aperture distributions of two images are matched by shifting horizontally and vertically. The proposed method is verified experimentally. The result shows that this method can realize the automatic searching and matching of the sub-aperture of SHWFS and enlarge the dynamic range of SHWFS..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 31 (2012)
Optical Models of the Key Refractive Elements in Human Eye Optical System
KONG Mei-mei, and GAO Zhi-shan
The cornea and crystalline lens are two key refractive elements of human eye optical system. In order to understand and research the optical performances of eye in refractive surgical procedures, optical models of cornea and crystalline lens are researched. Based on the corneal and lens optical performances, from the pThe cornea and crystalline lens are two key refractive elements of human eye optical system. In order to understand and research the optical performances of eye in refractive surgical procedures, optical models of cornea and crystalline lens are researched. Based on the corneal and lens optical performances, from the point of view of optical imaging, the analysis and study of optical models are presented with the optical design software Zemax and math tools. Based on the corneal bi-conic model, which is constructed by the basis of human eye model, the data of measured Chinese corneal parameters are statistically analyzed. Based on the crystalline lens gradient-index (GRIN) distribution, the lens refractive index distributions in axial and radial direction are analyzed. The statistical results of the measured Chinese corneal data are given, so the corneal model based on Chinese eyes is completed. A new single equation, which can be used to express the character of the lens refractive index distribution and a compact form, is achieved. The corneal surface model based on the data of measured Chinese corneal parameters and the lens GRIN distribution models can be applied to solve the key technology in the research of human eye optical system..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 36 (2012)
Lightweight Structure Design for Rectangular SiC Space Mirror
QI Guang, LI Jing-lin, WANG Shu-xin, and REN Jian-yue
To meet the requirements of high location accuracy and surface figure accuracy for rectangular space mirror, and to reduce mirror weight extremely at the same time, became the new and important research subject in most countries. The material selection, support form, geometry parameters and lightweight structure form aTo meet the requirements of high location accuracy and surface figure accuracy for rectangular space mirror, and to reduce mirror weight extremely at the same time, became the new and important research subject in most countries. The material selection, support form, geometry parameters and lightweight structure form are taken into account in the design of a rectangular space mirror. Putting forward the topology optimization ensures the mirror back lightweight form. By using finite element analysis technique, the static stiffness of the mirror is analyzed. The analysis results show that: the surface accuracy reaches λ/10 PV，λ/50 RMS (λ=632.8 nm) under gravity load, PV value is 7nm, RMS values is 1.68 nm, and the mirror component first-order natural frequency is 256 Hz, which is better than traditional structure forms of mirrors, and can meet the application requirements..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 43 (2012)
Research and Design of Super Short-focus Panoramic Fish-eye Lens
CHEN Sheng-cong, and LIN Feng
The relationship of super short-focus panoramic fish-eye lens’ focus and resolution was studied comprehensively. It is proved that the shorter the focus, the higher the resolution of scenic circle area. A panoramic fish-eye lens is presented, whose ratio of focus and image height is less than 0.35, horizontal field is The relationship of super short-focus panoramic fish-eye lens’ focus and resolution was studied comprehensively. It is proved that the shorter the focus, the higher the resolution of scenic circle area. A panoramic fish-eye lens is presented, whose ratio of focus and image height is less than 0.35, horizontal field is up to 360° and vertical field is more than 180°. The results show that the spatial pixel of scenic circle area with half vertical field 45-90 degree is up to 75%, and the modulation transformation function is greater than 0.4 at the spatial frequency of 200 lp/mm. Its imaging quality is very well, its resolution of stretching the scenic circle is very high, and it works for panoramic monitor and high definition..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 48 (2012)
Variable Focus Ionic Liquid Lens Based on Electrowetting
HU Xiao-dong, QU Chao, ZHANG Shi-guo, LU Liu-jin, MA Xiang-yuan, HE Yu-de, ZHANG Xiao-ping, and DENG You-quan
Variable focus lens based on ionic liquids is investigated by using electrowetting. The presented results show that focusing voltages are strongly affected with reflective index, i.e. driving voltage to obtain identical focal length is remarkably increased with increasing reflective index. The focusing voltage of the lVariable focus lens based on ionic liquids is investigated by using electrowetting. The presented results show that focusing voltages are strongly affected with reflective index, i.e. driving voltage to obtain identical focal length is remarkably increased with increasing reflective index. The focusing voltage of the lens (<80 V) is quite lower than that of the saline lens (>100 V). Moreover, the lens exhibits excellent performance over saline lens such as good tolerance of sharply temperature varying, wide operating temperature which is up to 80 oC and in particular high stability at high temperature. The adjustable range of focal length varies from 5 cm to the infinite with energy consumption several tenths of a milliwatt low. Besides, it could have potential application in near-infrared image system..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 53 (2012)
The Study of MWIR Multispectral Imaging Technology
LAN Wei-hua, WAN Min, WANG Kai, and YANG Xiao-ru
Multispectral imaging technology integrating spectral measuring with imaging technology, can detect the spectral and geometric characteristic of target simultaneously. The multispectral imaging has technical advantage in restraining the clutter backgrounds and identifying target. A multispectral imaging system with fouMultispectral imaging technology integrating spectral measuring with imaging technology, can detect the spectral and geometric characteristic of target simultaneously. The multispectral imaging has technical advantage in restraining the clutter backgrounds and identifying target. A multispectral imaging system with four channels working in Mid-wave Infrared (MWIR) band has been developed. Using the narrow optical filter and the infrared Focal Plane Array (FPA), the staring multispectral imaging system can work based on time sequence sweeping. According to the detector performance, the temperature sensitivity of each channel has been analyzed. For improving the sensitivity of each spectral channels，optical filters were schemed carefully to extend the integral time of the detector. Using the developed MWIR multispectral imaging system, the imaging test has been carried out, and the results of each channel have been compared..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 59 (2012)
Hyperspectral Imagery Classification Based on Spectral Clustering Band Selection
PENG Yan-bin, and AI Jie-qing
Hyperspectral image has been widely used in land-cover classification. Due to huge amount of data and high correlation between bands, band selection technology is main method to reduce computational complexity. According to non-linear relation between band data, Spectral Clustering (SC) is imported to cluster and selecHyperspectral image has been widely used in land-cover classification. Due to huge amount of data and high correlation between bands, band selection technology is main method to reduce computational complexity. According to non-linear relation between band data, Spectral Clustering (SC) is imported to cluster and select band. In this method, neighbor graph and similarity matrix are generated from band image samples, then samples are divided into k clusters by spectral clustering algorithm. At last, k selected representative samples are generated and used in the subsequent classification and recognition task. Experimental results show that new method can reduce computational complexity and improve classification accuracy of land-cover classification..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 63 (2012)
Laboratory Spectral Calibration Amendment Based on Spectrum Offset Correction Model
LI Lin, HU Yong, and WANG Yue-ming
Laboratory spectral calibration research of a dispersive hyperspectral imager is investigated. During laboratory spectrum acquisition, the heat generated inside the imager leads to center wavelength shifts. Due to the narrow bandwidth of hyperspectral imager, spectrum shifts will affect radiometric calibration accuracyLaboratory spectral calibration research of a dispersive hyperspectral imager is investigated. During laboratory spectrum acquisition, the heat generated inside the imager leads to center wavelength shifts. Due to the narrow bandwidth of hyperspectral imager, spectrum shifts will affect radiometric calibration accuracy. As a result, a spectrum offset correction model is put forward to correct spectral calibration. Moreover, correction precision is analyzed and radiance of integrating sphere is simulated according to spectral calibration results before and after correction. Compared with real integrating sphere data, it is proved that the model can correct spectral shifts well..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 68 (2012)
There-dimensional Surface Full Color Imaging of Microstructure by Fourier Transform
ZHOU Chong, WANG Hui, LI Yong, and BAI Xiao-hui
Analysis show that spectral information and three-dimensional shape structure data are both contained in Fourier transform imaging spectrometer’s interference signal. A new method of three-dimensional color shape measurement is proposed, which could measure spectral reflectance of each point on sample surface and threeAnalysis show that spectral information and three-dimensional shape structure data are both contained in Fourier transform imaging spectrometer’s interference signal. A new method of three-dimensional color shape measurement is proposed, which could measure spectral reflectance of each point on sample surface and three-dimensional shape data of sample, and then achieve the three-dimensional surface hyperspectral imaging. According to the texture mapping, three-dimensional data could be reconstructed in full-color about the microstructure colored-object. Experimental results demonstrate that the proposed method is effective..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 74 (2012)
Optical-phased-array (OPA) Technology Applied to Laser Radar
YE Zheng-yu, ZHAO Si-si, and WANG Zhi-yong
Based on the main application of laser radar, the significance and the latest progress of Optical-phased-array (OPA) technology were summarized. The basic principle of OPA was presented. Optical-phased-array technologies are classified according to typical materials, and illustrated in detail involving the key technoloBased on the main application of laser radar, the significance and the latest progress of Optical-phased-array (OPA) technology were summarized. The basic principle of OPA was presented. Optical-phased-array technologies are classified according to typical materials, and illustrated in detail involving the key technologies and the latest achievements correspondingly. The technologies are analyzed, compared and evaluated. Finally, the development of optical phased array technology applied to laser radar was prospected..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 81 (2012)
Evaluation Method on Design Quality of Continuous Phase Plate
ZHANG Da-zhi, and ZHANG Rong-zhu
In view of the continuous phase plate that was designed by GS algorithm with the characteristics of complex surface and difficulty in processing, a method for evaluating the phase plate was put forward by using both the surface shape and the focal spot parameters. Based on the actual design results, we calculated Peak In view of the continuous phase plate that was designed by GS algorithm with the characteristics of complex surface and difficulty in processing, a method for evaluating the phase plate was put forward by using both the surface shape and the focal spot parameters. Based on the actual design results, we calculated Peak Value (PV) and Root Mean Square (RMS) value of the phase plate and the characteristics of its focal spot. The feasibility of using peak value and RMS value as evaluation was analyzed. Finally, compared with the focal spot corresponding to three different phase plates, the PV, RMS value and power spectral density of focal spot were analyzed..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 87 (2012)
Band Gap Characteristic and Transmission Spectrum of Ring-shaped Holes Photonic Crystal in THz Range
ZHANG Xian-bin, MA Li-juan, YUAN Ke, and LI Yun-feng
Band gap of 2D triangular lattice photonic crystal with circular air holes and ring-shaped air holes in THz range was studied by using plane wave expansion method (PWM). It was found that complete band gap of circular holes was larger when the holes radius increased from 0.41a to 0.49a. For the same hole radius, ring-sBand gap of 2D triangular lattice photonic crystal with circular air holes and ring-shaped air holes in THz range was studied by using plane wave expansion method (PWM). It was found that complete band gap of circular holes was larger when the holes radius increased from 0.41a to 0.49a. For the same hole radius, ring-shaped holes photonic crystal could get the larger complete band gap than circular holes, and the optimal parameter was 0.169 8 THz when the holes radius of 0.47a, inner radius of 0.133a, was 1.15 times for circular holes structure. Transmission spectrum of ring-shaped holes photonic crystal was studied by finite-difference time-domain method (FDTD), and we designed the filter in (0.719 8 ～0.865 5) THz wave..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 94 (2012)
Simulation of Conoscopic Interference in Uniaxial Crystal Using Optical Software-Advanced System Analysis Program
LIN Yuan-fang, ZHENG Cheng, ZHENG Xiao-dong, WANG Xiao-ping, and LIU Xu
In order to simulate conoscopic interference in uniaxial crystal under different optical axis directions, beam divergence angles, crystal thicknesses or incident wavelengths, a method of writing and running an Advanced System Analysis Program (ASAP) command script was adopted. Functions of main commands were as followsIn order to simulate conoscopic interference in uniaxial crystal under different optical axis directions, beam divergence angles, crystal thicknesses or incident wavelengths, a method of writing and running an Advanced System Analysis Program (ASAP) command script was adopted. Functions of main commands were as follows: define geometries and optical properties of a polarizer, a crystal, an analyzer and a plane for observing interferograms. Create a set of divergence Gaussian beams and specify their coherence and propagation. Trace rays, calculate and display the exact complex field energy distribution characteristic on the observing plane. Simulation results show that, when the optical axis is perpendicular to the crystal surface, the interferogram consists of concentric interference fringes centered on the optical axis and is separated by a cross. When the optical axis is parallel to the crystal surface, the interferogram consists of two sets of hyperbola interference fringes with their symmetrical axis separately perpendicular and parallel to the optical axis. Their fringe densities both increase from inside to outside. When the optical axis is neither perpendicular nor parallel to the crystal surface, characteristics of the interference fringe vary with the specific directions of the optical axis. Once increase the beam divergence angle and the crystal thickness, or reduce the incident wavelength, fringes of the interferogram will move toward inside with their numbers increasing, and vice versa. The interferogram appearing when the polarizer is perpendicular to the analyzer is complementary to that appearing when the polarizer is parallel to the analyzer..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 98 (2012)
Analysis and Optimization of Clamping Schemes in Controlling KDP Crystal Surface
JIA Kai, YE Lang, CUI Kai-hong, XU Pan, YUAN Xiao-dong, and ZHANG Bin
A new kind of clamping scheme presented could make the crystal surface optimized, and numerical calculation is used to analyze the influence of crystal gravity sag on KDP surface and conversion efficiency by adopting the optimized scheme as well as routine schemes. The results show that optimized clamping scheme could A new kind of clamping scheme presented could make the crystal surface optimized, and numerical calculation is used to analyze the influence of crystal gravity sag on KDP surface and conversion efficiency by adopting the optimized scheme as well as routine schemes. The results show that optimized clamping scheme could improve the effects of KDP crystal gravity obviously. When the intensity of fundamental light is 5.5 GW/cm2, compared with routine schemes, the conversion efficiencies by adopting the optimized scheme increase 6.2%, 9.5% and 6.5%, respectively..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 104 (2012)
Performance and Parameters Selection Optimization Strategy of Stochastic Parallel Gradient Descent Image Matching Method
LI Song-yang, FU Si-hua, YIN Shi-liang, LONG Xue-jun, WANG San-hong, and HAN Hai-tao
Stochastic Parallel Gradient Descent (SPGD) image matching method is a new image matching method, which simultaneously imposes statistically independent random disturbances on all of the deformation parameters and use correlation coefficient stochastic gradient component to carry out an iterative operation instead of rStochastic Parallel Gradient Descent (SPGD) image matching method is a new image matching method, which simultaneously imposes statistically independent random disturbances on all of the deformation parameters and use correlation coefficient stochastic gradient component to carry out an iterative operation instead of real gradient component, so that it can obtain quick optimum parameter estimation. The selection of the disturbance amplitudes and the gain coefficients is the key issue that needs to be solved in this method. Presently, the question that, if we could select the same default parameters of universal adaptability in different deformation situation, or if we should update parameters to achieve the optimal matching results, has not got a better answer yet. On the one hand, this method’s utmost matching performance is explored in different preset conditions; on the other hand, it elementarily summarizes the laws of the impact on this method’s matching performance by selection of different disturbance amplitudes and gain coefficients. On the basis of the above, the grading parameters updating strategy is studied, so that this issue has been further addressed..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 109 (2012)
Dual-band High-definition Image Acquisition System
ZHANG Yan-chao, ZHAO Jian, SUN Qiang, and BI Guo-ling
In order to achieve real-time monitoring of long-range targets, and obtain detailed characteristics of targets comprehensively and clearly, a dual-band high-definition image acquisition system was designed. This system applied Gigabit Ethernet as data transmission path, made use of FPGA for resolution switching, and haIn order to achieve real-time monitoring of long-range targets, and obtain detailed characteristics of targets comprehensively and clearly, a dual-band high-definition image acquisition system was designed. This system applied Gigabit Ethernet as data transmission path, made use of FPGA for resolution switching, and had the auto focusing function separated in the visible and near-infrared bands. According to the requirements of monitoring mode, the image data acquired by the two detectors was set to a specific resolution, and then transferred to the host computer, on which the operations such as image storage, display and auto focusing were performed. Experiment results show that this system has achieved the functions of resolution switching and auto focusing flexibility according to the system requirements, and realized the real-time displaying of remote target video and high-definition storage both in the two bands by the Gigabit Ethernet..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 118 (2012)
Image Super-resolution Reconstruction Based on Smoothly Approximate Over-complete Sparse Representation
LU Jin-zheng, ZHANG Qi-heng, XU Zhi-yong, and PENG Zhen-ming
To improve resolution capacity of the degraded image, a learning-based super-resolution reconstruction method via sparse representation over over-complete dictionary is introduced. Due to non-sparsest representation of signal with respect to given ill-conditioned dictionary, the suggested smoothed L0 norm sparse-represTo improve resolution capacity of the degraded image, a learning-based super-resolution reconstruction method via sparse representation over over-complete dictionary is introduced. Due to non-sparsest representation of signal with respect to given ill-conditioned dictionary, the suggested smoothed L0 norm sparse-representation technique over blind sparsity with continuous descending function can exhaustively exploit given specific dictionary, achieving effective sparse decomposition of low resolution image patch. Afterwards, the stable and convergent solvers are obtained from optimization of gradient steepest descent. Experimental results demonstrate that, compared to Bicubic interpolation, the Power Signal to Noise Ratio (PSNR) gain of image thrice-zoomed is close to 2 dB, and the improvement of Structural Similarity (SSIM) is almost 0.04. Moreover, the super-resolved images eliminated excessive blurring degradation and annoying edge artifacts. The proposed method can be effectively applied to resolution enhancement of degraded single-image..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 123 (2012)
The Sensitization Technology of Chemical Silvering for Optical Surfaces
GONG Xiu-ming, WU Shi-bin, and JING Hong-wei
The basic procedure for the chemical silvering for optical surfaces is introduced, the principle and technology of the sensitization is reported, and the theoretical analysis and experimental validation of water spraying is given. An experiment was performed using a secondary mirror with 365mm in diameter. By spraying The basic procedure for the chemical silvering for optical surfaces is introduced, the principle and technology of the sensitization is reported, and the theoretical analysis and experimental validation of water spraying is given. An experiment was performed using a secondary mirror with 365mm in diameter. By spraying water for 35 seconds, the Cl-in sensitizer can be cleaned thoroughly, and the Sn(OH)2 gelinite is left on the optical surface uniformly. The silver coating is very good. The silver coating has the 92% reflectivity, 60nm thickness, PV=λ/45 and RMS=λ/250 in surface change, which meets the coating requirements for the secondary mirror..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 130 (2012)
Characteristics of Single Layer HfO2 Thin Films
AI Wan-jun, and XIONG Sheng-ming
Single layer HfO2 thin films have been prepared respectively by Electron Beam Evaporation (EBD), Ion Assisted Deposition (IAD) and Ion Beam Reactive Sputtering (IBRS). Crystal structures, optical properties, surface topography and absorption of these deposited films have been studied. It is found that thin film propertSingle layer HfO2 thin films have been prepared respectively by Electron Beam Evaporation (EBD), Ion Assisted Deposition (IAD) and Ion Beam Reactive Sputtering (IBRS). Crystal structures, optical properties, surface topography and absorption of these deposited films have been studied. It is found that thin film properties have a close relationship with deposition technologies. The EBD and IBRS films are largely amorphous, whereas the IAD films are polycrystalline. Comparison with EBD films, the IAD and IBRS films, of which the structures are very compact, display higher refractive index, surface roughness and absorption. The optical band gap energy of these films are found to be 5.30～5.43 eV, and the corresponding optical absorption edge range are found to be from 228.4 nm to 234.0 nm..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 134 (2012)
A New Photopolymerizable Holographic Recording Materials Based on Polyvinyl Alcohol and 2-Hydroxyethyl Acrylate
MA Chen, ZHANG Bao-min, ZHOU Bi-cheng, YAN Li-li, and QIAO Miao-jie
We have developed a new polyvinylalcohol-based photopolymeric holographic recording material. The recording is obtained by the copolymerization of acrylamide and 2-Hydroxyethyl Acrylate (HEA). Diffraction efficiencies near 75% are obtained with exposure energy of 231 mJ/cm2 in materials of 95 μm thickness. The effect oWe have developed a new polyvinylalcohol-based photopolymeric holographic recording material. The recording is obtained by the copolymerization of acrylamide and 2-Hydroxyethyl Acrylate (HEA). Diffraction efficiencies near 75% are obtained with exposure energy of 231 mJ/cm2 in materials of 95 μm thickness. The effect of different concentration HEA on the holographic parameters, such as moral absorption coefficient, quantum yield, refractive index modulation, thickness etc., is studied, by applying a nonlinear procedure based on Levenberg Marquardt's algorithms. The addition of HEA can improve the optical quality and increase the thickness of the film, which results in improved storage capacity for holographic optical storage..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 141 (2012)
Preparation and Investigation of Textured AZO Transparent Conductive Thin Film by Directly Dry Etching
WANG Wen-na, ZHANG Da-wei, TAO Chun-xian, HUANG Yuan-shen, NI Zheng-ji, and ZHUANG Song-lin
Aluminum-doped Zinc Oxide (AZO) transparent conductive thin films were prepared by RF sputtering and surface-textured AZO transparent conductive thin films were obtained by using ion etching. Effects of ion etching on the optical, electrical and structural properties of the films were investigated. A slight decrease waAluminum-doped Zinc Oxide (AZO) transparent conductive thin films were prepared by RF sputtering and surface-textured AZO transparent conductive thin films were obtained by using ion etching. Effects of ion etching on the optical, electrical and structural properties of the films were investigated. A slight decrease was found in transmittance, but the transmittance is still more than 80% in the visible spectrum. The resistivity increased slightly, but still at the 10-3.·cm level, the minimum resistivity is 2.91×10-3.·cm. The surface topography changed noticeably after ion etching. Most films show "pit-like" structure, lateral dimensions in the 0.5～1.0 μm, opening angle 120° or so, and Root Mean Square (RMS) roughness increased from 7.29 nm to 36.64 nm. The films have good surface micro-structure, and show a good prospect as solar cells front-electrode..
Opto-Electronic Engineering
- Publication Date: Jan. 01, 1900
- Vol. 39, Issue 2, 147 (2012)
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