Contents
2011
Volume: 31 Issue 12
54 Article(s)
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Atmospheric Optics and Oceanic Optics
Predicted Space-Varying Point Spread Function Model for Anisoplanatic Adaptive Optics Imaging
Chang Xiang, Li Rongwang, and Xiong Yaoheng
The point spread function (PSF) of an adaptive optics (AO) system evolves in larger region than isoplanatic patch in the field of view (FOV). This variation strongly limits the efficient utilization of AO images. A theoretical expression of this space-varying PSF is derived by analysis of characteristics of AO imaging The point spread function (PSF) of an adaptive optics (AO) system evolves in larger region than isoplanatic patch in the field of view (FOV). This variation strongly limits the efficient utilization of AO images. A theoretical expression of this space-varying PSF is derived by analysis of characteristics of AO imaging system. Then by combining the space-field statistical characteristics of AO compensation and atmospheric turbulence theory a predicted space-varying parameter PSF model for AO systems is developed and the effectiveness of the model is also tested by employing the predicted space-varying PSF model in reconstruction of AO astronomical image with deconvolution method, which can reduce effects of residual wave-front distortion and anisoplanatism on AO system′s partial compensated astronomical images..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1201001 (2011)
Confirmation of the Quadratic Approximation of Rytov Phase Structure Function and the Approximation of Complex Gaussian-Function Expansion of Hard-Edge Apertures
[in Chinese], [in Chinese], and [in Chinese]
The propagation of truncated Gaussian beams through atmospheric turbulence is taken as an example. The analytical results (i.e., the intensity distribution, the second-moment beam width, power in the bucket and β parameter), which are obtained by using the quadratic approximation of Rytov′s phase structure function andThe propagation of truncated Gaussian beams through atmospheric turbulence is taken as an example. The analytical results (i.e., the intensity distribution, the second-moment beam width, power in the bucket and β parameter), which are obtained by using the quadratic approximation of Rytov′s phase structure function and complex Gaussian expansion method, are compared with those obtained by using numerical simulation and experimental methods. It is shown that the analytical results are nearly in agreement with those obtained by using numerical simulation and experimental methods. In addition, reasonable explanations to differences between different methods are also given..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1201002 (2011)
Research on Multi-Aperture Reception in Wireless Laser Communication
Ke Xizheng, Song Peng, and Pei Guoqiang
In atmospheric laser communications, light intensity flashing caused by turbulence severely interferes the performance of communication system and increases the bit error rate (BER) of the system. Multi-aperture reception is the effective method to overcome the above interference. The reception areas of multi aperturesIn atmospheric laser communications, light intensity flashing caused by turbulence severely interferes the performance of communication system and increases the bit error rate (BER) of the system. Multi-aperture reception is the effective method to overcome the above interference. The reception areas of multi apertures and the effect of aperture position relation on space smoothing factor are analyzed. The reception performance of three apertures, is mainly analyzed and smoothing factor of multi-aperture reception is compared with that of single-aperture reception. The probability density function of light intensity fluctuation deriving from the Gamma-Gamma channel modeling from weak turbulence band to strong turbulence band is deployed to analyze the BER of multi-aperture reception system. The result shows that multi-aperture reception system can better improve the light intensity fluctuation of reception area and decrease system′s BER. With the increase of the number of aperture, the aperture smoothing factor and BER will be decreased..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1201003 (2011)
Coherence and Statistical Optics
Coherence Properties of the Three-Dimensional Scattering Field Generated by an Anisotropic Quasi-Homogeneous Medium
Chen Jingjing, Xin Yu, Chen Yanru, Chen Feinan, and Wang Yongqing
Based on the scattering theory of electromagnetic wave, the electromagnetic scattering field generated by an anisotropic quasi-homogeneous medium is investigated. Then the analysis formulas for spectral density and spectral degree of coherence of the electromagnetic scattering field are derived. Simulation results showBased on the scattering theory of electromagnetic wave, the electromagnetic scattering field generated by an anisotropic quasi-homogeneous medium is investigated. Then the analysis formulas for spectral density and spectral degree of coherence of the electromagnetic scattering field are derived. Simulation results show that when the scattering potential matrix of the anisotropic quasi-homogeneous medium is Gaussian-correlated, the normalized spectral density of the anisotropic medium is close to the average of the corresponding isotropic medium. But the weight of every component is not only different from each other but also changing as the scattering angle changes. The spectral degree of coherence of the anisotropic medium is greatly different from that of of its corresponding isotropic medium. The spectral degree of coherence of the anisotropic medium is oscillating as a function of the angle by three phases. And at some certain scattering angles, the spectral degree of coherence of the anisotropic medium is nearly the same as that of the corresponding isotropic medium..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1203001 (2011)
Diffraction and Gratings
Research on Two-Dimensional Coherent Laser Array Beam Combination Using Conjugate Dammann Grating
Li Bing, Yan Aimin, Lü Xiaoyu, Sun Jianfeng, and Liu Liren
Phase-locked coherent laser array beam combination using conjugate Dammann grating and phase compensation is used to achieve high power and high brightness coherent beam combination. Theoretical analysis of the beam combination of 5×5 and 32×32 two-dimensional laser arrays using conjugate Dammann grating is cPhase-locked coherent laser array beam combination using conjugate Dammann grating and phase compensation is used to achieve high power and high brightness coherent beam combination. Theoretical analysis of the beam combination of 5×5 and 32×32 two-dimensional laser arrays using conjugate Dammann grating is carried out through numerical simulation, and the influences of the errors in the phase values of the phase plate, the matching and positioning of the conjugate Dammann grating to the beam combination efficiency during the experiment are also studied. The results of theoretical analysis and numerical simulation show that this is an efficient beam combination technique, however, these errors have a great influence on the total beam combination efficiency. This means that the manufacturing of the phase plate and positioning of the conjugate Dammann grating should be taken great care of during the experiment and the development of high power laser system based on conjugate Dammann grating, which will benefit the development of the compact, light, high efficiency and high beam quality high-power laser system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1205001 (2011)
Reproducing Colored Image with Guided-Mode Resonance Gratings Array
Xu Banglian, Huang Yuanshen, Wang Qi, Tao Chunxian, Zhang Dawei, Ni Zhengji, and Zhuang Songlin
A method of reproducing colored image with guided-mode resonance (GMR) gratings array is presented. It is different from traditional color impression which uses three kinds of pigment mixed to obtain various colors, but utilizes the filtering characteristics of grating to extract red, green and blue light which can be A method of reproducing colored image with guided-mode resonance (GMR) gratings array is presented. It is different from traditional color impression which uses three kinds of pigment mixed to obtain various colors, but utilizes the filtering characteristics of grating to extract red, green and blue light which can be acted as three primary colors from natural light. As GMR grating shows strong resonant peak at specific wavelength as well as low sideband when illuminated by polarized light, monochromatic light with high purity can be obtained easily. In order to reduce the difficulty of actual manufacturing, only the period of grating is altered to shift the resonant position. After getting the three kinds of basic grating structures, colored image can be reappearred by distributing them. Computer simulation shows that using this method can restore colored images factually when the incident light is TE-polarized..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1205002 (2011)
Analysis of Two-Dimensional Pinhole Vector Diffraction in Visible Light
Xu Jiajun, and Xing Tingwen
The modern optical systems have placed stringent requirements on the manufactures and measurements of optical elements. Measurement accuracy of nanometer is needed. Phase-shift point diffraction interferometer is a common instrument in high-accuracy measurement, whose reference wave is generated by a pinhole with diameThe modern optical systems have placed stringent requirements on the manufactures and measurements of optical elements. Measurement accuracy of nanometer is needed. Phase-shift point diffraction interferometer is a common instrument in high-accuracy measurement, whose reference wave is generated by a pinhole with diameter of several hundred nanometers. So the measurement accuracy can be estimated by analyzing the diffracted reference wave. A two-dimensional simulation, based on finite element method (FEM), is set up to study the propagation of the visible light of 632.8 nm wavelength, through sub-1000 nm diameter pinholes in a chromium membrane with different thicknesses. Beam spot alignment error and tilt are also analyzed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1205003 (2011)
Research on Transmission Mechanism of the Structurally Changed Long Period Photonic Crystal Fiber Grating
Qi Yuefeng, Guo Wenguang, and Bi Weihong
The influence of holes collapse in photonic crystal fiber cladding on transmission characteristics is analyzed in detail. The structure model of photonic crystal fiber with collapse holes is built. Using finite element method and coupled local-mode theory, the distribution of effective refractive indexes and mode couplThe influence of holes collapse in photonic crystal fiber cladding on transmission characteristics is analyzed in detail. The structure model of photonic crystal fiber with collapse holes is built. Using finite element method and coupled local-mode theory, the distribution of effective refractive indexes and mode coupling coefficients are calculated in the structural change region, where periodic ringlike collapse is induced. Then the mode effective refractive indexes and the distribution of coupling coefficients in modulation region can be obtained. The coupling rules between the core-mode and the cladding-modes are studied, and the transmission spectrum is obtained, which consists of two peaks formed by the couplings of LP01-LP11 and LP01-LP02 modes. The feasibility of this grating fabrication technique based on structural change is also discussed. On this basis, the influence of the fiber structural parameters on transmission characteristics are further studied involving in the grating period, the number of periods, the depth of cladding collapse. Thus the laws of resonance peaks varying with these parameters can be got. The research results indicate that the periodic holes collapse in photonic crystal fiber cladding can form grating. The transmission characteristics can be tuned by changing the collapse parameters. This result can provide theoretical basis for design and fabrication of structural photonic crystal fiber grating..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1205004 (2011)
Imaging Systems
Research on Flat Field Correction Method in Adaptive Optics Retinal Imaging System
Kong Ningning, Li Chao, Xia Mingliang, Qi Yue, Li Dayu, and Xuan Li
A flat-field correction method is proposed to eliminate the interference fringes on the retinal photoreceptor images which origin from the etaloning effect in the thinned back illuminated CCD. First of all, the generation mechanism of etaloning effect is analyzed. Different from other flat-field method which uses the iA flat-field correction method is proposed to eliminate the interference fringes on the retinal photoreceptor images which origin from the etaloning effect in the thinned back illuminated CCD. First of all, the generation mechanism of etaloning effect is analyzed. Different from other flat-field method which uses the image of white balance reflectance target as reference image, the retinal image without adaptive optics compensation is used as reference image for flat-field correction method in this experiment, and the calibration result using the new reference image has a significant improvement compared with the result calibrated using the white balance reflectance target as reference image. As a means to quantify the calibrated result of flat-field method, the average power spectra of the photoreceptor image is calculated. The mean value of the average power spectra for the image after calibration is improvedly 132.1% compared with the image before calibration in the range of spatial frequency 70 and 90 lp/(°). Experimental result indicates that the image of retinal photoreceptor has a significant improvement using flat-field correction method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1211001 (2011)
Three-Dimensional Superresolving Phase Optical Pupil Filter with Polynomial Function
Zhou Guozun, Tian Weijian, and Chen Huifang
In order to study far-field optical imaging system with continuous phase optical pupil filter and to achieve the purpose of high resolution in this system, a phase optical pupil filter with polynomial function is proposed. With this filter, three-dimensional super-resolution can be obtained in optical system. The contrIn order to study far-field optical imaging system with continuous phase optical pupil filter and to achieve the purpose of high resolution in this system, a phase optical pupil filter with polynomial function is proposed. With this filter, three-dimensional super-resolution can be obtained in optical system. The contrast with the effects on super-resolution of a typical three-zone phase optical pupil filter is shown in the following. There is a significant improvement on transverse resolution with the new type filter, but the Strehl ratio will decline. In addition, more adjustable parameters can be established to restrain such a filter by increasing the highest power of the polynomial function, which makes the filter more flexible in improving the resolution of optical system. The numerical results about the continuous-phase optical pupil filter with polynomial functions will also help the manufacture..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1211002 (2011)
Target Detection in Hyperspectral Image Using Projection Pursuit Based on Chaotic Particle Swarm Optimization
Wu Chao, and Wu Yiquan
Aimed at the problem of unsupervised target detection in hyperspectral image, a target detection method using projection pursuit (PP) based on chaotic particle swarm optimization (PSO) is proposed. Chaotic PSO can speed up the process of PP and get more accurate optimal projection direction. Adaptive band selection is Aimed at the problem of unsupervised target detection in hyperspectral image, a target detection method using projection pursuit (PP) based on chaotic particle swarm optimization (PSO) is proposed. Chaotic PSO can speed up the process of PP and get more accurate optimal projection direction. Adaptive band selection is used for the dimensional reduction of hyperspectral image. Skewness and kurtosis which are susceptible to outliers are chosen to design the projection index. And chaotic PSO is applied to search for optimal projection direction. Thus the target information can be projected into low-dimensional space effectively. The target is extracted from projection images by histogram segmentation. Experiments with qualitative and quantitative evaluation are carried out for many images, and the detection results of the proposed method are compared with those of genetic algorithm PP method and RX method. The results show that the proposed method detects target in hyperspectral images more effectively and significantly reduces the running time..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1211003 (2011)
Three-Dimensional Imaging Lidar Signal Denoising Method Based on Empirical Mode Decomposition
Jiao Hongwei, Qin Shiqiao, Wang Xingshu, Hu Chunsheng, and Wu Wei
A grads method is used to process lidar signal, by which the scopes and positions of abrupt change can be detected. Based on these grads messages, a translation sequence can be calculated and is added to original lidar signal, which makes the parts of abrupt change in original lidar signal removed. The abrupt change reA grads method is used to process lidar signal, by which the scopes and positions of abrupt change can be detected. Based on these grads messages, a translation sequence can be calculated and is added to original lidar signal, which makes the parts of abrupt change in original lidar signal removed. The abrupt change removed signal is decomposed and denoised by empirical mode decomposition, which can avoid mode mix and local surge phenomena. This denoising method is applied to real lidar data denoising. The experiment results show the effectiveness of this method. It can remove noise in signal effectively in flat part and keep abrupt change well in signal..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1211004 (2011)
Analysis of Wave-front Coding System with Primary Astigmatism and Coma by Using Ray Aberration Approach
Chen Shouqian, Fan Zhigang, Wang Shuai, and Xu Zhigao
In the view of geometrical optics, the imaging characteristics of the wavefront coding system suffering from primary astigmatism or primary coma are analyzed. The ray aberrations of wave-front coding system suffering from primary astigmatism or primary coma are derived. Analytical expressions for the upper and lower boIn the view of geometrical optics, the imaging characteristics of the wavefront coding system suffering from primary astigmatism or primary coma are analyzed. The ray aberrations of wave-front coding system suffering from primary astigmatism or primary coma are derived. Analytical expressions for the upper and lower boundary of ray aberrations are obtained by using ray aberrations theory. In the wavefront coding system, the sensitivity to primary astigmatism or primary coma are analyzed by the way aberrations and spot diagram. When the wavefront coding systems suffer from out-of-focus and primary astigmatism, the similarity of out-of-focus modulation transfer function (MTF) has a low sensitivity to primary astigmatism while the recoverability of blurred encoding images has a high sensitivity to primary astigmatism. When the wavefront coding systems suffer from out-of-focus and primary coma, the ray aberrations have an asymmetrical distribution because the ray aberration for tangential is different from that for sagittal. Therefore, there is a different imaging characteristic between tangential and sagittal. Moreover, the similarity and recoverability of blurred encoding images have a high sensitivity to primary coma..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1211005 (2011)
Analysis on Spectrum Recovery for Nonuniform Sampling Interferogram
Jing Juanjuan, Xiangli Bin, and Lü Qunbo
Traditional fast Fourier transform (FFT) is only useful in uniform sampled interferogram. For nonuniform sampled interferogram, the spectrum recovered by FFT is often distorted when the aliasing is neglected. To solve the problem, nonuniform fast Fourier transform (NUFFT) method is proposed and some mature theories areTraditional fast Fourier transform (FFT) is only useful in uniform sampled interferogram. For nonuniform sampled interferogram, the spectrum recovered by FFT is often distorted when the aliasing is neglected. To solve the problem, nonuniform fast Fourier transform (NUFFT) method is proposed and some mature theories are formed. The NUFFT is applied to the spectrum recovery of interferogram, and the interferogram at different sampling frequency and different degree of nonuniform optical path difference (OPD) is analyzed and simulated. The results indicate that sampling frequency is the main factor that affect the recovery precision for undersampled interferogram condition, while the nonuniform degree of OPD is more affective for oversampled interferogram condition. In the application, data quantity, sampling frequency and the nonuniform degree of OPD must be considered comprehensively to acquire the final design parameter. To ensure the recovery precision, avoiding the undersampling of gotten interferogram is the basic criteria..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1211006 (2011)
Imaging Algorithm of Fresnel Telescope Based on Resampling Interpolation
Lü Xiaoyu, Yan Aimin, Li Bing, Dai Enwen, Sun Jianfeng, and Liu Liren
Fresnel telescope (short for Fresnel telescope full-aperture synthesized imaging lidar) is a new high resolution active laser imaging technique. In one-dimensional scanning operational mode of Fresnel telescope, spatial distribution of sampling signal is non-uniform because of the relative motion between target and scaFresnel telescope (short for Fresnel telescope full-aperture synthesized imaging lidar) is a new high resolution active laser imaging technique. In one-dimensional scanning operational mode of Fresnel telescope, spatial distribution of sampling signal is non-uniform because of the relative motion between target and scanning beam, which affects the fast Fourier transform in the following matched filtering algorithm. We propose the complete imaging algorithm for Fresnel telescopy, including space-time transform, resampling interpolation and matched filtering, in which we use resampling interpolation to transform the signal into two-dimensional uniform distribution form. Three different resampling interpolation methods are analyzed, and we get good reconstruction results of point target and area target with computer simulation, which prove that the designed imaging algorithm for Fresnel telescope is effective. This work has substantial practical value and offers significant benefit for Fresnel telescopy imaging system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1211007 (2011)
Instrumentation, Measurement and Metrology
Inner Hole Range-Finding Sensor with Laser Triangulation Based on Trapezoid Prism
Xiong Zhiyong, and Zhao Bin
In order to realize the inner-hole-depth measurement and the profile of the bottom surface measurement of parts with holes, especially deep-hole parts, an inner hole measuring sensor with laser triangulation was designed. The applied designs such as mechanical structure and optical designs, system imaging characteristiIn order to realize the inner-hole-depth measurement and the profile of the bottom surface measurement of parts with holes, especially deep-hole parts, an inner hole measuring sensor with laser triangulation was designed. The applied designs such as mechanical structure and optical designs, system imaging characteristics, and the analysis and evaluation of optical aberration based on the software Zemax were investigated. First of all, by using focusing lens, the laser light is focused to the surface to be measured, and flare is small enough. Then, put the required scattering light limit in a narrow range using the trapezoid prism total reflection characteristics. Finally, an imaging lens is used to make light foculize on CCD target surface. According to the geometric relation between the flare on CCD and hole depth, the depth of the hole and the profile of the bottom surface was calculated. Experimental results indicated that the measurement precision can reach 1 μm, and the design of using trapezoidal prism can well solve the problem of physical space limited as measuring inner hole. The combination with the principle of laser triangulation technique makes the system satisfy the requirements of simple structure, stabilization, higher precision and rapid speed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1212001 (2011)
A New Background Radiation-Balanced Model for the Size-of-Source Effect Measurement
Yuan Zundong
The background radiation effect of the measurement for the size-of-source effect (SSE) of radiation thermometers must be considered at low and median temperature. The calculation model includes items of radiation thermometer outputs to measure an infinite-size radiation source. After analyzing the influence of the deteThe background radiation effect of the measurement for the size-of-source effect (SSE) of radiation thermometers must be considered at low and median temperature. The calculation model includes items of radiation thermometer outputs to measure an infinite-size radiation source. After analyzing the influence of the detector temperature on the models of temperature and SSE measurements, a novel calculation model, utilizing a suppositional detector temperature balanced with the background radiation for the SSE measurement is presented. This method prevents the need for an infinite-size radiation source and unavoidable approximation. The relations of the SSE and the increase of temperature reading are given. The measurement conditions of the source temperature, reading resolution and thermometer emissivity setting are analyzed to optimize the result of the SSE measurement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1212002 (2011)
Measurement and Overcoming of Nonlinear Chirp in Synthetic Aperture Imaging Ladar
Luan Zhu, Zhou Yu, Dai Enwen, Sun Jianfeng, and Liu Liren
The nonlinear chirp of tunable laser in synthetic aperture imaging ladar (SAIL) can degrade the range resolution and influence the azimuth resolution. The polynomial nonlinear coefficients of laser frequency changed with time are measured by a fiber Fabry-Perot interferometer. The results of experiment are presented. BThe nonlinear chirp of tunable laser in synthetic aperture imaging ladar (SAIL) can degrade the range resolution and influence the azimuth resolution. The polynomial nonlinear coefficients of laser frequency changed with time are measured by a fiber Fabry-Perot interferometer. The results of experiment are presented. Based on the data the Fourier frequency spectrum of the point target is discussed on the condition of the different frequency linearity. The spectral width and phase errors are reduced through changing the sampling pulse width. It is one method to compensate the degradation of resolution. The optimized sampling pulse width is derived at the phase error better than π/4 corresponding to the optical diffraction limit..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1212003 (2011)
Improved Measurement Method for X-Ray Focus Projection Coordinates of 3D-CT Scanning System
Li Xingdong, Yang Min, Li Dehong, and Liu Wenli
X-ray focus projection coordinates are the important geometrical parameters for three-dimensional (3D) CT reconstruction. But for practical 3D-CT scanning system, it is impossible to measure the position of the X-ray focus projection by direct means. An improved method to measure the X-ray focus projection coordinates X-ray focus projection coordinates are the important geometrical parameters for three-dimensional (3D) CT reconstruction. But for practical 3D-CT scanning system, it is impossible to measure the position of the X-ray focus projection by direct means. An improved method to measure the X-ray focus projection coordinates with high accuracy is proposed. Through acquiring digital radiographic (DR) images of the single ball object at different positions in the cone X-ray beam, the DR images are combined to several groups which include two correlative DR images. Image processing methods are used so as to get the centroid of each projection of the ball object at different position and then to construct an over-determined equation set. By solving the over-determined equation set, the X-ray focus projection coordinates are finally obtained. The experimental results prove that the improved method is free of the severe requirements of the elliptical projection shape according to the existing method, and the accuracy of this method can satisfy the requirements of the practical scanning systems, meanwhile it is easy to realize and of high anti-noise ability..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1212004 (2011)
Determination of Spectral Quantum Efficiency of Silicon Photodetector
Lin Yandong, Lü Liang, and Bai Shan
The determination of quantum efficiency of a photodetector is of great importance in radiometry. External quantum efficiency of windowless silicon photodetectors is measured with cryogenic radiometer at ten wavelengths of He-Ne, Ar+-Kr+ and Tisapphire lasers. Based upon measured reflectance at three laser wavelengths, The determination of quantum efficiency of a photodetector is of great importance in radiometry. External quantum efficiency of windowless silicon photodetectors is measured with cryogenic radiometer at ten wavelengths of He-Ne, Ar+-Kr+ and Tisapphire lasers. Based upon measured reflectance at three laser wavelengths, the thickness of the silicon dioxide layer is obtained through least square method according to the relation between surface reflectance of a photodetector and the thickness of its silicon dioxide layer. Spectral reflectance of the photodetector surface is thereby obtained. Internal quantum efficiency is calculated from surface reflectance and external quantum efficiency result at the laser wavelengths, and spectral quantum efficiency is fitted. The deviation of modeled result from experimental result is within 1.5×10-4 in the spectral range from 488 to 900 nm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1212005 (2011)
Reversion Algorithm for Liquid Column Parameters with Rainbow Refractometry Based on Debye Theory
Song Feihu, Xu Chuanlong, and Wang Shimin
Rainbow refractometry is a non-intrusive technology for determining the refractive index and diameter of liquid column simultaneously. An objective function is designed to quantify the deviation between the low frequency component of the captured rainbow and the simulated rainbow with Debye theory (p=2). Further, a novRainbow refractometry is a non-intrusive technology for determining the refractive index and diameter of liquid column simultaneously. An objective function is designed to quantify the deviation between the low frequency component of the captured rainbow and the simulated rainbow with Debye theory (p=2). Further, a novel inversion algorithm for liquid column based on Debye theory (p=2) and the objective function is proposed. Experiments are carried out to evaluate the performance of the algorithm. Results show that the relative error of the radius is less than 8%, the absolute error of the refractive index is less than 5×10-4 and the detection limit of the radius is as low as 60 μm with in the radius range of 50~500 μm and the refractive index range of 1.32~1.56..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1212006 (2011)
Specular Shape Measurement with Phase Measuring Deflectometry Based on Bundle Adjustment
Xiao Yongliang, Su Xianyu, and Chen Wenjing
In order to simplify the system calibration and reduce the influence of the error of system calibration and image noise on measurement accuracy by phase measuring deflectometry (PMD), free frame of axes is introduced in PMD, and bundle adjustment in free frame of axes is performed to improve the measurement accuracy. CIn order to simplify the system calibration and reduce the influence of the error of system calibration and image noise on measurement accuracy by phase measuring deflectometry (PMD), free frame of axes is introduced in PMD, and bundle adjustment in free frame of axes is performed to improve the measurement accuracy. Commonly, the specular shape is measured by PMD with gradient information. However, bundle adjustment can not be directly performed since there is no absolute height information. The introduction of free frame unifies the incident and reflected ray in the same frame, and the absolute coordinate of tested points can be obtained by intersection of incidence and reflected ray. According to the geometrical constraint that, the 3D points must be located on the corresponding incident ray, constraint bundle adjustment is performed to refine the intrinsic, extrinsic parameters and 3D coordinates of shape simultaneously to minimize the reprojection error. Numerical simulation and experimental results demonstrate that bundle adjustment can indeed improve the measurement accuracy in PMD..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1212007 (2011)
Temperature Influence on Fizeau Interferometer Repeatability
Miao Erlong, and Gu Yongqiang
High precision repeatability is the precondition of testing accuracy and also one of the most important parameters of high precision testing. In Fizeau interferometer, the interferometer cavity is sensitive to environments, especially to temperature variation. Temperature is also one of the main factors that influence High precision repeatability is the precondition of testing accuracy and also one of the most important parameters of high precision testing. In Fizeau interferometer, the interferometer cavity is sensitive to environments, especially to temperature variation. Temperature is also one of the main factors that influence the test repeatability. The interferometer cavity model is established based on Edlen equations according to light transmission theory. The theoretical analysis shows that the repeatability is mainly affected by the cavity length and the temperature variation. The repeatability variation is tested through ZYGO interferometer at different environments and different cavity lengths. The test and computation results are compared and analyzed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1212008 (2011)
Integrated Optics
Vertical Nano-Microring Resonators with Enhanced Tolerance to Fabrication Misalignments
Le Zichun, Li Rui, Hu Jinhua, and Dong Wen
Microring resonators are key components in nowadays photonic integrated circuits. A vertical microring resonator with enhanced tolerance to fabrication misalignments is introduced. Both straight and microring waveguides are with relatively high refractive-index difference between the core and cladding, therefore the veMicroring resonators are key components in nowadays photonic integrated circuits. A vertical microring resonator with enhanced tolerance to fabrication misalignments is introduced. Both straight and microring waveguides are with relatively high refractive-index difference between the core and cladding, therefore the vertical microring resonator is compact and confines the power efficiently. Based on coupling mode theory, the coupling coefficient is derived as a function of the coupling layer thickness (d) and the transverse offset (Δ) between the straight and microring waveguides. The analytic solutions are used to confine the range of three-dimensional finite-different time-domain (3D-FDTD) simulations for their efficiency. In addition, the tolerance of d and Δ is studied by taking consideration of actual fabrication technology for the vertical nano-microring resonator. The analytic solutions and simulation results show that when d=30 nm, the vertical microring resonator has a large coupling coefficient even Δ is varied from 130 to 265 nm. It is verified that the vertical nano-microring resonator has enhanced tolerance to fabrication misalignments..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1213001 (2011)
Research on Cut-Off Process of Optical Stopping Effect in Amorphous As2S8 Thin-Film Waveguide
Wang Guande, Chen Baoxue, Hiromi Hamanaka, and Mamoru Iso
The cut-off process of optical stopping effect in thin film waveguide with doping As2S8 and pure As2S8 is studied. Based on this, the chemical bond structures of the samples are analyzed. With the help of the theory of hybridize valence orbital and the theory of electron energy band gap, the dynamical equation of opticThe cut-off process of optical stopping effect in thin film waveguide with doping As2S8 and pure As2S8 is studied. Based on this, the chemical bond structures of the samples are analyzed. With the help of the theory of hybridize valence orbital and the theory of electron energy band gap, the dynamical equation of optical stopping effect is proposed. The numerical analysis results are well agreable with the experimental data, and the cut-off process of optical stopping effect can be explained by the deduction of this model. It reveals the mechanism of cut-off process of optical stopping effect..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1213002 (2011)
Lasers and Laser Optics
A Model of Region Defects under Nanosecond Pulsed Laser
Yu Zhenkun, Qi Hongji, Zhao Yuan′an, and He Hongbo
An improved laser induced damage (LID) model of absorbing defects causing temperature rise in material is given. Starting with the equation of heat conduction and based on the single-defect LID model, this model gives the absorption cross section of inclusions by Mie theory. The effective interaction distance of defectAn improved laser induced damage (LID) model of absorbing defects causing temperature rise in material is given. Starting with the equation of heat conduction and based on the single-defect LID model, this model gives the absorption cross section of inclusions by Mie theory. The effective interaction distance of defects in the substrate, namely the thermal diffusion length of substrate which is determined by the thermal proerties of substrate material and inclusions, is calculated. The result shows that, considering the influence of inclusions in the substrate, the obtained LID threshold (LIDT) is closer to the result of experiment than single-defect model. Meanwhile, the result of surface LIDT is very consistent with the experimental time scale of F∝t0.5..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1214001 (2011)
Study of Aberration Correction in Light Path of Adaptive Optical System
Jiang Pengzhi, Ma Haotong, Zou Yongchao, and Du Shaojun
The correction of the aberrations in light path of adaptive optical system is of great importance. However, the diffraction effect of the laser beam propagation in the adaptive optical system limits the correction effect of the aberration. By means of stochastic parallel gradient descent, correction effect under differThe correction of the aberrations in light path of adaptive optical system is of great importance. However, the diffraction effect of the laser beam propagation in the adaptive optical system limits the correction effect of the aberration. By means of stochastic parallel gradient descent, correction effect under different Fresnel numbers is calculated, and an improved method is proposed. The simulated and experimental result indicates that the compensative effect decreases with the decrease of Fresnel numbers, and the correction effect of the improved solution is better than the traditional solution, and little influence of the diffraction effect is on the correction effect of the aberration with the former..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1214002 (2011)
All-Fiberized Yb Fiber Laser with Passively Generated Sub-Nanosecond Pulse Output
Liu Wei, Chen Tao, Dai Jianning, Jiang Peipei, Wu Bo, and Shen Yonghang
A novel all-fiberized Yb-doped fiber laser configuration for passively sub-nanosecond pulse generation is reported. By splicing a piece of Bi/Cr codoped silica fiber to a section of Yb-doped double clad fiber of 15 m in a fiber Bragg grating constructed fiber laser cavity, stable sub-nanosecond pulse train is obtained A novel all-fiberized Yb-doped fiber laser configuration for passively sub-nanosecond pulse generation is reported. By splicing a piece of Bi/Cr codoped silica fiber to a section of Yb-doped double clad fiber of 15 m in a fiber Bragg grating constructed fiber laser cavity, stable sub-nanosecond pulse train is obtained with a maximal repetition rate of 50.2 kHz and an average output power of 2 W. The calculated peak power exceeds 30 kW. The linear dependence of the pulse repetition rate on the absorbed pump power is confirmed. It is also found that stimulated Brillouin scattering plays a crucial role in the pulse generation. Broadband infrared supercontinuum emission is detected via the Bi/Cr fiber end, which spans over 1000 nm with spectral intensity variation lower than 5 dB..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1214003 (2011)
Materials
Study on Time Characteristics of Fast Time Response Plastics Scintillator EJ-232
Peng Xiaoshi, Wang Feng, Xu Tao, Liu Yonggang, Liu Shenye, Mei Yu, and Chen Ming
EJ-232 is a kind of plastics scintillator with fast time response and decay time, it acts as a neutron-to-light converter in the system of nuclear reaction measurement. Time characteristics of EJ-232 plastics scintillator are measured by using short-pulse laser to excit scintillator in size of Φ6 mm×1 mm and Φ6 mmEJ-232 is a kind of plastics scintillator with fast time response and decay time, it acts as a neutron-to-light converter in the system of nuclear reaction measurement. Time characteristics of EJ-232 plastics scintillator are measured by using short-pulse laser to excit scintillator in size of Φ6 mm×1 mm and Φ6 mm×2 mm (excited at 263 nm). The results show that the rise time is less than 30 ps for EJ-232 plastics scintillator and the laser excited fluorescence decay constant of the scintillator are 0.6 ns and 1.1 ns. The neutron excited fluorescence decay constant of the scintillator is longer than the laser excited fluorescence decay constant..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1216001 (2011)
A New Process for Surface Texture of Multicrystalline Silicon
Wang Yingmin, Cheng Zexiu, Li Qinghua, Jiang Longying, and Liu Qi
Electrochemical etching and chemical acid etching are used to optimize the surface texture for improving the conversion efficiency of multicrystalline silicon solar cells. The effect of different current densities on the surface morphology of multicrystalline silicon is studied by the method of electrochemical etching Electrochemical etching and chemical acid etching are used to optimize the surface texture for improving the conversion efficiency of multicrystalline silicon solar cells. The effect of different current densities on the surface morphology of multicrystalline silicon is studied by the method of electrochemical etching in the HF and CH3CH2OH solution with the volume ratio of 12; then the surface loose structure of the multicrystalline silicon is removed through the chemical acid etching to form high performance surface texture. Surface morphology of multicrystalline silicon is characterized by scanning electron microscopy. The results show that the surface porous structure of the multicrystalline silicon is fabricated after electrochemical etching for 300 s while the favorable current density is 30 mA/cm2. After ultrasonic etching for 60 s in the chemical acid solution with the volume ratio of HF to H2O2 of 41 at room temperature, the surface texture with hole diameter of 2~4 μm and hole depth of 1.5~2 μm is fabricated. It has good light-trap and anti-reflection effects on improving the conversion efficiency of multicrystalline silicon solar cells..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1216002 (2011)
Microscopy
Fluorescence Endomicroscopy with Adaptive Imaging Function
Feng Zhifeng, Wang Liqiang, Lu Zukang, and Duan Huilong
A kind of fluorescence endomicroscopy which can be used for in-vivo imaging in diagnosis and photodynamic therapy is described. According to the fluorescence signal intensity detected, the fluorescence endomicroscope can adjust the excitation power in different regions rapidly using feedback algorithm, to obtain high sA kind of fluorescence endomicroscopy which can be used for in-vivo imaging in diagnosis and photodynamic therapy is described. According to the fluorescence signal intensity detected, the fluorescence endomicroscope can adjust the excitation power in different regions rapidly using feedback algorithm, to obtain high signal noise ratio (SNR) and high dynamic range images, and achieve interactive fluorescence diagnosis and photodynamic analysis. It can also adjust the light dose continuously according to the feedback treatment effect, getting the best results of photodynamic therapy. Dynamic adjustment of excitation intensity is realized by the ON-OFF state and the residence time of computer-controlled digital micromirror device. The outer diameter of the fluorescence endomicroscope is 8 mm, working length is 250.3 mm. It can be assembled in the sheath tube of standard laparoscope, and adapted to in vivo microscopic imaging diagnosis of the lesion easily. The experimental results show that the field of view is 600 μm, optical resolution is better than 2.2 μm, and the image dynamic range can be enhanced more than 200 times. The fluorescence endomicroscope can improve the details and SNR of fluorescence saturation regions and fluorescence weak regions, and improve diagnostic accuracy at the same time. This technology can be extended to confocal 3D imaging further, and achieve in vivo histological analysis..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1218001 (2011)
Nonlinear Optics
Study on Output Characteristics of Mutually Pumped Phase Conjugation with Multiple Coupled Interaction Regions
Jiang Zhiguo, Liu Jifang, Ma Lin, Shi Shunxiang, and Sun Yanling
Based on the photorefractive self-bending successive four-wave mixing interaction theory, a computational model of mutually pumped phase conjugation (MPPC) with multiple coupled interaction regions is proposed to analyze the output characteristics under an electronics-like point of view on four-wave mixing. Using the mBased on the photorefractive self-bending successive four-wave mixing interaction theory, a computational model of mutually pumped phase conjugation (MPPC) with multiple coupled interaction regions is proposed to analyze the output characteristics under an electronics-like point of view on four-wave mixing. Using the model, the influence of threshold coupling strength and phase-conjugate reflectivity on transmissivity between the coupled interaction regions is investigated. The smaller transmissivity will decrease the phase-conjugate reflectivity under the same coupling constant and increase the threshold coupling constant. The output characteristics of bird wing MPPC are studied with experiment, and the dependence of phase-conjugate reflectivity of MPPC on the incident position is presented. An output characteristics model of bird wing MPPC with four coupled interaction regions is proposed, and simulation conclusions are in agreement with the experimental results..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1219001 (2011)
Optical Design and Fabrication
Compact Collimator Design for High-Brightness Light-Emitting Diode
Jing Lei, Liu Hua, Zhao Huifu, Lu Zhenwu, Xu Zhijun, Han Xuebing, and Li Yefan
In order to meet the requirements of collimating illumination for high-brightness light-emitting diode (LED) and overcome the shortcomings of traditional LED collimator′s large aspect ratio and heavy structure, a novel collimator with small aspect ratio, compact structure and high collimation is presented. The design oIn order to meet the requirements of collimating illumination for high-brightness light-emitting diode (LED) and overcome the shortcomings of traditional LED collimator′s large aspect ratio and heavy structure, a novel collimator with small aspect ratio, compact structure and high collimation is presented. The design of collimator is based on the assumption that the LED source is ideal point source. The rays are reflected twice in the collimator. According to the theory of the constant optical path length and the refraction law in geometric optics, the profiles of collimator′s surface are obtained through numerical solution of the constant optical path length equations, and the aspect ratio is 0.1. Using the optical software TracePro, the collimator system is traced and simulated. The results show that the divergence angle (full angular width of the radiation pattern at the half intensity) is just 5.4° for a point source with the diameter of exit aperture is 50 mm; but it changes to 6° for an actual high brightness white LED, and the irradiance uniformity and the optical efficiency within a diameter of spot 60 mm are 92% and 52.11% at 1 m respectively, which is suitable for the illuminating area of light brighteness LED. The design realizes the objectives of compact structure and high collimation, and the tolerances meet the requirements of alignment, which provides an effective way for realizing the illuminating system′s miniaturization and simplification..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1222001 (2011)
Design for LED Lamps with High Color Rendering Index
Cao Yujie, Jin Shangzhong, and Cen Songyuan
Aiming at the insufficiency of color rendering of existing light-emitting diode (LED) based lamps used for indoor lighting, a solution of LED modules consisting of three different kinds of LED is proposed. Correlated color temperature (CCT), color rendering index (CRI) and luminous efficiency (LER) of LED modules are cAiming at the insufficiency of color rendering of existing light-emitting diode (LED) based lamps used for indoor lighting, a solution of LED modules consisting of three different kinds of LED is proposed. Correlated color temperature (CCT), color rendering index (CRI) and luminous efficiency (LER) of LED modules are calculated when different numbers of three kinds of LED are set respectively. Influences of changing the number of each kind of LED on the results are analyzed. Besides, the selections of optimized combinations are described by setting results on CCT values of 3800 K and 4800 K as examples. Moreover, ideal results with high CRI (90 around) as well as good LER on different CCT values (3400 K~5600 K) are acquired. This solution is easier to impletment and more suitable for indoor lighting lamps compared with other methods used for improving CRI of white LED. This result may provide some guidance for the design of LED-based lamps with satisfying CRI for quality lighting..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1222002 (2011)
Study on Characteristics of Aberrations for an Active Liquid Lens in Lithographic Objective Lens
Yuan Wenquan, and Gong Yan
In order to compensate aberrations of lithographic objective lens, an active liquid lens is developed, and characteristics of the aberrations varying of the active liquid lens is analyzed. The active liquid lens is constituted of deionised water and LiF. Firstly, considering the gravity and hydrostatic pressure, the foIn order to compensate aberrations of lithographic objective lens, an active liquid lens is developed, and characteristics of the aberrations varying of the active liquid lens is analyzed. The active liquid lens is constituted of deionised water and LiF. Firstly, considering the gravity and hydrostatic pressure, the forces are evenly applied to one to six points which are equally settled, and the deflection of lens is calculated; Secondly, deflection of the deformable lens is fitted with Zernike polynomials, and the functional relation between the aberrations expressed by standard Zernike polynomials and mechanical forces is established. The results show that: relation between the standard Zernike polynomial coefficients of active liquid lens and forces acted on it is strongly linear; First three aberrations of the active liquid lens are piston, defocus, and n-foil under multi-points forces except one point; With number of the force points increasing, defocus and piston regulating abilities of active liquid lens are of increasing trend, while the other kinds of aberrations regulating abilities are of downward trend..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1222003 (2011)
Fabrication and Characterization of THz Waveguides with Silicon Wafer by Using Cylinder Segments as Scatterers
Wan Yong, Yun Maojin, Pan Shudi, and Xia Linhua
A novel kind of scattererscylinder segments has been designed. Based on this design, a series of photonic crystal waveguides, including structures of dielectric pillars in air and structures of air holes in dielectric, are fabricated on silicon wafer. The measurement results demonstrate that the structures of dielectriA novel kind of scattererscylinder segments has been designed. Based on this design, a series of photonic crystal waveguides, including structures of dielectric pillars in air and structures of air holes in dielectric, are fabricated on silicon wafer. The measurement results demonstrate that the structures of dielectric pillars in air can form band gaps more easily than the structures of air holes in dielectric, and the former can also tune the widths and positions of the band gaps by changing the parameter e. For the same structure of dielectric pillars in air, the band gap position in the optical transmission spectra moves toward the shorter-wavelength edge when the angle of incidence along the long axis becomes larger, indicating that the structure has the property of anisotropy..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1222004 (2011)
Simulation and Fabracation of Multi-Micromirrors Used in Infrared Spectrometer
Zheng Ying, Liang Zhongzhu, and Liang Jingqiu
With the modernized development of environmental science, weather observation and space detection and so on, it is an urgent requirement to carry out the research of portable and real-time supervised Fourier transform spectroscope in the leading basic research. A new micro-spaced modulated Fourier transform infrared spWith the modernized development of environmental science, weather observation and space detection and so on, it is an urgent requirement to carry out the research of portable and real-time supervised Fourier transform spectroscope in the leading basic research. A new micro-spaced modulated Fourier transform infrared spectroscope is proposed, without moving parts in this configuration. Thereinto, two multi-micromirrors are the key components in the interferometric system. The effect on the recovery spectra of the height of steps and the roughness of reflective surfaces in multi-micromirrors is simulated, and the height error of steps that can be tolerated by the system is ±0.18 μm, and the biggest roughness is settled at 150 and 200 nm. The multi-micromirror is fabricated by lithography-electroplating. The test result of the roughness of the reflectives surfaces of the multi-micro mirror (RMS) is 90.23 nm, and the height error of steps is ±0.1 μm, which meet the requirement of the design..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1222005 (2011)
Lens Design for Optical System of High Zoom Ratio
Jiang Lun, and Huang Wei
A high zoom-ratio zoom structure type is introduced, which is composed of zoom imaging group and zoom reimaging group. The zoom ratio of system is the product of the two zoom groups. The size and numerical aperture of the intermediate image plane can be changed in the zoom process, when system is in short focal length A high zoom-ratio zoom structure type is introduced, which is composed of zoom imaging group and zoom reimaging group. The zoom ratio of system is the product of the two zoom groups. The size and numerical aperture of the intermediate image plane can be changed in the zoom process, when system is in short focal length position, the height of the immediate image is large while the numeric aperture is small. When system is in long focal length, the height of the immediate image is small while the numeric aperture is large. This will help to correct aberrations of image. Compared with the traditional zoom system, this type of zoom system structure is easier to obtain high zoom ratio. Using this structure a 80× cooled long-wave infrared zoom system is designed. The modulation transfer function (MTF) is above 0.26 in all focal length at the spatial frequency of 14 lp/mm. The result indicates that the structure can be used to achieve high zoom ratio zoom system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1222006 (2011)
Optimized Design of Silver Superlens for the Surface Plasmon Polaritons Interference Lithography Based on Backside-Exposure Technique
Xiao Xiao, Zhang Zhiyou, He Mingyang, Xiao Zhigang, and Xu Defu
Photolithography resolution could be enhanced by the local enhancement effects of surface plasmon polaritons (SPP). Large-area periodic nanostructures could be fabricated by backside exposure SPP interference lithography. Resonance transmission of SPP in backside exposure system is analyzed, an optimum design method isPhotolithography resolution could be enhanced by the local enhancement effects of surface plasmon polaritons (SPP). Large-area periodic nanostructures could be fabricated by backside exposure SPP interference lithography. Resonance transmission of SPP in backside exposure system is analyzed, an optimum design method is proposed for silver superlens, and the intensity distribution of SPP interference lithography is simulated by finite difference time domain (FDTD) method and theoretic formulas. With optimum design of superlens thickness and resonance angle, a periodic silt array is obtained with better quality in laboratory..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1222007 (2011)
Optics at Surfaces
Arbitrary Polarization Transformation Based on Two-Dimensional Metallic Rectangular Gratings
Chen Juan, Yan Lianshan, Pan Wei, Luo Bin, and Guo Zhen
Based on the birefringence effect of one-dimensional subwavelength metallic grating and equivalent medium theory (EMT) is generalize to a two-dimensional subwavelength structure to analyze a two-dimensional metallic rectangular gratings in order to realize the control of polarized state from incidnet linear polarizatioBased on the birefringence effect of one-dimensional subwavelength metallic grating and equivalent medium theory (EMT) is generalize to a two-dimensional subwavelength structure to analyze a two-dimensional metallic rectangular gratings in order to realize the control of polarized state from incidnet linear polarization to output arbitrary polarized state transformation. Finite difference time domain (FDTD) algorithm is performed to analyze properties of polarization and transmittance of the light. Simulation results show that the full Poincaré sphere coverage could be obtained theoretically by space angle modulation, and the high transmittance can be achieved as well..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1224001 (2011)
Physical Optics
Optimization of Color Filter Liquid-Crystal-on-Silicon Microdisplays Based on Three-Dimensional Optical Modeling
Zhang Baolong, Li Dan, Dai Fengzhi, Yang Shifeng, and Kwok Hoising
With the three-dimensional (3D) optical analysis as a tool, the optimization of the fringing field effect in the color filter liquid-crystal-on-silicon (CF-LCoS) microdisplays is obtained by changing pixel arrangement, rubbing direction, and liquid crystal (LC) mode. The color purity of the CF-LCoS microdisplays could With the three-dimensional (3D) optical analysis as a tool, the optimization of the fringing field effect in the color filter liquid-crystal-on-silicon (CF-LCoS) microdisplays is obtained by changing pixel arrangement, rubbing direction, and liquid crystal (LC) mode. The color purity of the CF-LCoS microdisplays could attain 63% national television system committee (NTSC) level for a typical pixel size of 15 μm. With the optimization, the color fringing effect of CF-LCoS is minimized and the color purity of the device is increased..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1226001 (2011)
Influence of Beam Incoherence on the Lateral Shifts of Defect Modes in Photonic Crystals
Wang Yali, Chen Yuanyuan, and Shi Jielong
The propagation properties of incoherent light beams through a one-dimensional photonic crystal with a defect layer are investigated by means of incoherent theory and transfer matrix method. The influence of incoherence and the incident angle on the transmitted lateral shifts of defect modes and the lateral shifts on tThe propagation properties of incoherent light beams through a one-dimensional photonic crystal with a defect layer are investigated by means of incoherent theory and transfer matrix method. The influence of incoherence and the incident angle on the transmitted lateral shifts of defect modes and the lateral shifts on the reflecting surface of the photonic crystal are discussed. The transmitted and reflected lateral shifts are both enhanced with the strengthening of coherence. In comparison with the pass band of one-dimensional photonic crystal without a defect layer, it is found that the defect layer will increase the transmitted shift. In different incoherent conditions, the shift of defect modes is always lager than that of other waves in pass band..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1226002 (2011)
Remote Sensing and Sensors
Dust Automatic Detection over Ocean Using MTSAT Data
Tu Qianguang, Hao Zengzhou, Pan Delu, and Gong Fang
For the purpose of automatic detection of dust over ocean from satellites, reflection and emission characteristic of water surface, cloud and dust regions are analyzed based on lots of MTSAT satellite data, which show that the brightness temperature at thermal infrared channel 1 BT11 is less than the brightness temperaFor the purpose of automatic detection of dust over ocean from satellites, reflection and emission characteristic of water surface, cloud and dust regions are analyzed based on lots of MTSAT satellite data, which show that the brightness temperature at thermal infrared channel 1 BT11 is less than the brightness temperature at thermal infrared channel 2 BT12 in dust sample regions. The visible reflectance of dust sample is generally greater than water surface but less than clouds, while it is opposite at BT11, which confirms that even the atmospheric water vapor content over ocean is relatively high; BT11 is less than BT12 in dust regions by using Libradtran radiative transfer model package. This can be used as an important feature of dust detection over ocean. So an easy dust automatic detection algorithm over ocean by remote sensing using MTSAT satellite data is developed. The thresholds of this algorithm are derived from reflectance, 3 pixel×3 pixel standard deviation of visible channel, BT11 and difference between BT11 and BT12. Then progress of dust storms over the Bohai Sea and the Yellow Sea from March 1st to 2nd, 2008 and from March 19th to 21st, 2010 was monitored both the daytime and nighttime. Result indicates that the method can extract distribution area of dust over ocean and shows transportation process of dust storms objectively. This is in favor of aerosol optical thickness retrieval to estimate the flux of dust sedimentation over ocean..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1228001 (2011)
Receiving Characteristics of Coherent Ladar under Partially Coherent Condition
Pu Lili, Zhou Yu, Sun Jianfeng, Shen Baoliang, Lu Wei, and Liu Liren
The effects of signal spatial coherent characteristics and receiving aperture size on normalized carrier-to-noise ratio (RnCN) and field of view for coherent detection (Ωf) are investigated. In the model of remote laser radar detection, the expressions of RnCN and the receiving theory are presented. Further numerical sThe effects of signal spatial coherent characteristics and receiving aperture size on normalized carrier-to-noise ratio (RnCN) and field of view for coherent detection (Ωf) are investigated. In the model of remote laser radar detection, the expressions of RnCN and the receiving theory are presented. Further numerical simulations show that when the Gaussian local oscillation beam size is larger than the receiving aperture size, RnCN will reach saturation, in addition, the spatial coherent length and aperture radius can both improve RnCN, but will reduce Ωf. Based on the theoretical analysis and numerical simulation, the relation is presented that the product of RnCN and field of view is proportional to λ2, which is unaffected by the coherent characteristics. At last, the dependence of RnCN on the detection height and ground range under the turbulence model of Hufnagel-Valley 5/7 is analyzed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1228002 (2011)
Composite Kernel Target Detection Based on Mathematical Morphology for Hyperspectral Imagery
Zhao Liaoying, Shen Yinhe, Li Xiaorun, and Cui Jiantao
In the base of kernel signature space orthogonal projection (KSSP), a composite kernel signature space orthogonal projection (CKSSP) technique, which combines spectral information with spatial information, is proposed for target detection in nonlinearly mixed hyperspectral imagery. The grey mathematical morphological tIn the base of kernel signature space orthogonal projection (KSSP), a composite kernel signature space orthogonal projection (CKSSP) technique, which combines spectral information with spatial information, is proposed for target detection in nonlinearly mixed hyperspectral imagery. The grey mathematical morphological transform is extended into multivariate mathematical morphological transform based on marginal ordering and reduced ordering, respectively. The pixel distance is used as ordering scale function to establish reduced ordering. Extended mathematical morphological method with multi-structure elements is used to extract spatial information of hyperspectral images. Combining the spectral and spatial information, the composite kernel function is constructed and improved according to kernel function definition. Target is detected by CKSSP. The proposed method not only sufficiently applies the spectral information, but also effectively takes into account the spatial information. Experimental results of simulated data demonstrate that root mean square error of CKSSP is 0.03 less than that of KSSP, Experimental results of real data and the receiver operating characteristic curves show that CKSSP approach slightly outperforms the KSSP method in target detection..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1228003 (2011)
Spectroscopy
Study on Properties of Plasma Spectroscopy of Laser-Induced Carbon Materials with Different Chemical Forms
Zhong Ziming, Lu Jidong, Zheng Jianping, and Dong Meirong
Four kinds of samples (graphite, CaCO3, NH2C6H4SO3H and coal) with different forms of carbon are used for laser-induced breakdown spectroscopy (LIBS) experiment. Different gases (air, nitrogen, argon) are used to analyze the influence of gases on atomic emission spectrum and molecular emission spectrum for carbon materFour kinds of samples (graphite, CaCO3, NH2C6H4SO3H and coal) with different forms of carbon are used for laser-induced breakdown spectroscopy (LIBS) experiment. Different gases (air, nitrogen, argon) are used to analyze the influence of gases on atomic emission spectrum and molecular emission spectrum for carbon materials to study the LIBS properties for the carbon materials with different forms. The results show that the variation rules of neutral atomic emission C I intensities are that the strongest is in argon, the medium is in air and weakest in nitrogen. Since there are reversible reactions among molecular emission C2, N2 and CN, the variation rules of molecular emission C2 and CN depend on not only whether the samples themselves contain C-C, C=C or C-N, but also the interaction mechanism between the plasma and surrounding environment..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1230001 (2011)
Laser Induced Breakdown Spectroscopy of Chromium in Water Solution
Xu Yuan, Yao Mingyin, Liu Muhua, Lei Zejian, Peng Qiumei, Zhang Xu, and Chen Tianbing
In order to obtain a method for real-time and quantitative detection of the chromium element in industrial wastewater or sewage solution, trace heavy metal element chromium in K2Cr2O7 solution is measured by laser induced breakdown spectroscopy (LIBS). The temporal evolution property and the influence of the pulse laseIn order to obtain a method for real-time and quantitative detection of the chromium element in industrial wastewater or sewage solution, trace heavy metal element chromium in K2Cr2O7 solution is measured by laser induced breakdown spectroscopy (LIBS). The temporal evolution property and the influence of the pulse laser energies on the LIBS signal of Cr element are investigated respectively. The spectrum intensity is measured. The calibration curve of the Cr element is obtained from the measurement of the Cr 425.44 nm spectral line intensities with the Cr concentration ranging from 5×10-5 to 4×10-3. The experimental results show that the best time delay for spectrum detection is 1.28 μs and the optimal pulse laser energy is 120 mJ. The LIBS detection limit of Cr in the solution is 6×10-6 obtained from the measured calibration curve. This study indicates that LIBS can be applied to the real-time, quantitative detection of Cr element in solution with a good detection limit..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1230002 (2011)
Research on the Influence of Etalon Structures of LED on Differential Optical Absorption Spectroscopy System for Measuring NO2 and Its Removing Methods
Ling Liuyi, Xie Pinhua, Qin Min, Wang Jie, Si Fuqi, Li Ang, Hu Renzhi, Ye Conglei, Liu Jianguo, and Liu Wenqing
Light-emitting diode (LED) is a promising new type of light source for differential optical absorption spectroscopy (DOAS). Fabry-Perot etalon structures in the emission spectrum of some LED, however, influence DOAS retrievals. The cause of emergence of these structures in a blue LED (Luxeon, LXHL-LR3C) and the relatioLight-emitting diode (LED) is a promising new type of light source for differential optical absorption spectroscopy (DOAS). Fabry-Perot etalon structures in the emission spectrum of some LED, however, influence DOAS retrievals. The cause of emergence of these structures in a blue LED (Luxeon, LXHL-LR3C) and the relation between them and the angle of incidence are analyzed. The emission spectrum of LED may become smooth by tilting the LED in the fiber coupling so as to remove the etalon structures. Long-path DOAS measurements on atmospheric NO2 are carried out with the LED with four different angles of incidence and the measurement results are compared with these of conventional long-path DOAS with an arc lamp. The results show that NO2 concentrations are in very good agreement with one another when tilting angle is 30°. The detection limit of long-path DOAS measurements with the LED is only about 13% of that without tilting LED. These prove that if selected angle of incidence is so appropriate that the spectrum of LED becomes smooth, the influence of etalon structures of LED on DOAS retrievals can be effectively removed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1230003 (2011)
Thin Films
Preparation and Characterization of WO3 Thin Films Doped with TiO2 and Ag Nano Layer
Lü Gang, u Yonggang, Wu Heyun, Xia Zihuan, and Liu Renchen
Tungsten-oxide thin films have been prepared by doped silver and titania in the manner of layers or symbiosis, respectively. Morphology and static optical properties of the composite films have been investigated by means of scanning electron microscope (SEM) and atomic force microscope (AFM), ultraviolet-visible spectrTungsten-oxide thin films have been prepared by doped silver and titania in the manner of layers or symbiosis, respectively. Morphology and static optical properties of the composite films have been investigated by means of scanning electron microscope (SEM) and atomic force microscope (AFM), ultraviolet-visible spectrophotometer (UV757CRT) respectively. Chronoamperometry (CHI604C) is carried out and spectral measurements are performed in situ when films are tested. Results show that the films are good in adhesion to substrate. They have relatively compact structure and high coloration efficiency, improved by an average of 52.85% compared with the original tungsten-oxide thin films, and the variation of transmittance (bleached/colored) can reach 87.64% (λ=600 nm, colored time 20 s)..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1231001 (2011)
Dependence of Optical Properties on Thickness of Sb2Te3 Film
Zhang Kui, Geng Yongyou, Wu Yiqun, Dun Aihuan, and Li Hao
Super-resolution nea-field structure (super-RENS) is one new optical storage technique which can overcome the optical diffraction limit to write and read the recording pits by a functional thin film structure. In general, the performance of super-RENS is mainly determined by the mask material. The microstructure and moSuper-resolution nea-field structure (super-RENS) is one new optical storage technique which can overcome the optical diffraction limit to write and read the recording pits by a functional thin film structure. In general, the performance of super-RENS is mainly determined by the mask material. The microstructure and morphology of the as-deposited Sb2Te3 film are observed by transmission electron microscope (TEM). The dependences of optical properties on thickness of the Sb2Te3 films are carried out by ellipsometer and optical spectrometer, respectively. The results indicate that the as-deposited Sb2Te3 film is partly crystallized. Moreover, the optical properties change a lot within a certain thickness range. The extinction coefficient and refractivity of Sb2Te3 film decrease with the increase of thickness when the thickness is very small. Moreover, the optical constants tend to be stable when the thickness reaches a critical value. This critical value is 80 nm for the extinction coefficient, and 50 nm for refractivity of the film. The relationship betwean the optical property and thickness of Sb2Te3 film can be explained by the continuity of film structure..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1231002 (2011)
Reflective Color Filters Based on Metal-Dielectric Thin Films
Yu Peng, Shen Weidong, Zhang Yueguang, Niu Hailiang, and Liu Xu
Reflective color filters with metal-dielectric thin films in visible range are designed based on induced reflection method. High-absorption chromium and high-reflection aluminum enable these color filters to acquire both high reflectance and cut-off level in a broadband spectral region. Red, green and blue reflective fReflective color filters with metal-dielectric thin films in visible range are designed based on induced reflection method. High-absorption chromium and high-reflection aluminum enable these color filters to acquire both high reflectance and cut-off level in a broadband spectral region. Red, green and blue reflective filters with the reflectance larger than 72% and wide color gamut are obtained by adjusting thickness of their matching dielectric layers respectively for proper admittance matching. Filter samples are experimentally fabricated and the measured results agree well with those of the simulation. According to the halftone technique, filter arrays with different area duty ratios are prepared by lithography and stripping technology to realize optical reflective units with high resolution and intermediate colors among red, green and blue..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1231003 (2011)
Vision, Color, and Visual Optics
Color Characterization Method for Colorful Inkjet Printers
Jin Chongchao, Shen Huiliang, Shao Sijie, and John H. Xin
A novel color characterization method for general colorful inkjet printers is proposed. The method investigates the printer color separation and medium color rendering processes, based on which spectral reflectance can be predicted. The Yule-Nielsen special Neugebauer (YNSN) and enhanced YNSN models, which are based onA novel color characterization method for general colorful inkjet printers is proposed. The method investigates the printer color separation and medium color rendering processes, based on which spectral reflectance can be predicted. The Yule-Nielsen special Neugebauer (YNSN) and enhanced YNSN models, which are based on simple and complicated dot gain respectively, are employed in the printer color separation process. As the color separation cannot be directly controlled, the colorimetric error objective function is designed. The mapping between RGB and CMYK is modeled using polynomial regression, and is resolved by nonlinear optimization. Experiment results show that the proposed method can characterize the color printer accurately. In comparison with existing techniques using simple color separation model, the proposed method produces improved colorimetric accuracy..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1233001 (2011)
Color Characterization of LCD Based on Spectral Additive Properties
Liu Haoxue, Zheng Lan, Dai Li, Huang Min, and Wu Bing
For the color characterization of liquid crystal display (LCD), the spectral radiance curves are measured for EIZO CG 19 and NEC PA241 LCD monitors and the displayed colors are calculated based on spectral additive property. The results show that the spectral radiance curve of displayed color is the linear superpositioFor the color characterization of liquid crystal display (LCD), the spectral radiance curves are measured for EIZO CG 19 and NEC PA241 LCD monitors and the displayed colors are calculated based on spectral additive property. The results show that the spectral radiance curve of displayed color is the linear superposition of those of corresponding primaries, and there is a cubic polynomial relation between the digital driving value and the corresponding radiance of a single wavelength. A new color computation method is proposed. The computation accuracy of the proposed method is very high. It can be used for the color characterization of LCD..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1233002 (2011)
An Analysis of Omnidirectional 3D Display System Based on Scanning LED
Yao Zhenning, Li Haifeng, Liu Di, and Liu Xu
An omnidirectional 3D display system is built with the use of scanning LED and cylindrical parallax barrier. To improve image quality, the imaging principle of this system is analysed. The relation between system structure and display parameters, such as resolution, refresh rate and display space, is discussed. A methoAn omnidirectional 3D display system is built with the use of scanning LED and cylindrical parallax barrier. To improve image quality, the imaging principle of this system is analysed. The relation between system structure and display parameters, such as resolution, refresh rate and display space, is discussed. A method to increase the resolution is also proposed. Based on the analysis result, an experimental display system is produced. The images have a resolution of 1380 circumferential pixels and 480 vertical pixels, achieving a single-view-angle resolution of 233 pixel×480 pixel within a cylindrical space of 383 mm×480 mm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 1233003 (2011)
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