Contents
2016
Volume: 36 Issue 1
41 Article(s)
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Detectors
Semi-Parametric Model Kinematic Calibration of Photoelectric Detecting System
Luo Anzhi, Sun Hui, Jia Hongguang, and Zhao Ming
In order to meet the high pointing precision of photoelectric detecting system, a kinematic calibration algorithm using penalized least square method and bicubic spline interpolation is proposed to decrease the pointing error. According to the structure component of the photoelectric detecting system, the parametric moIn order to meet the high pointing precision of photoelectric detecting system, a kinematic calibration algorithm using penalized least square method and bicubic spline interpolation is proposed to decrease the pointing error. According to the structure component of the photoelectric detecting system, the parametric model of pointing error is established by multi- body system theory. In consideration of the non- parametric component, semiparametric model is established, and the model is calibrated by penalized least square method to get the modified model. A prototype experimental platform is built, and two groups of data are measured, which are collected to calibrate the model and verify the modified results. The experimental results demonstrate that the mean values of azimuth and elevation pointing error are reduced from 92.1185″, 75.9358″ to 2.7100″, 2.7755″. The standard deviation values of azimuth and elevation pointing error are also reduced from 21.6522, 15.1744 to 10.8645, 10.7305. The experiment and results can make it clear that the algorithm is able to improve the pointing precision and stability of pointing effectively. Besides, the linear and nonlinear relationships are considered simultaneously..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 104001 (2016)
Diffraction and Gratings
Effect on Polychromatic Integral Diffraction Efficiency for Two-Layer Diffractive Optics
Mao Shan, and Cui Qingfeng
Two- layer diffractive optics can achieve high diffraction efficiency at broad wavelength band. Manufacturing errors can result in loss of diffraction efficiency and further, influence modulation transfer function (MTF) of refractive and diffractive hybrid imaging optical system. Based on the expression of phase delay Two- layer diffractive optics can achieve high diffraction efficiency at broad wavelength band. Manufacturing errors can result in loss of diffraction efficiency and further, influence modulation transfer function (MTF) of refractive and diffractive hybrid imaging optical system. Based on the expression of phase delay and polychromatic integral diffraction efficiency (PIDE), mathematical analysis model of relationship between manufacturing errors and polychromatic integral diffraction efficiency is presented. Two kinds of manufacturing errors applied in 8~12 μm far infrared optical system which results in diffraction efficiency of two-layer diffractive optics are studied. Method of PIDE can evaluate image quality of optical system over broadband wavelength. According to the relationship between PIDE and manufacturing errors, MTF for hybrid optical system consisting of two-layer diffractive optics can be analyzed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 105001 (2016)
Study on the Energy Oscillation and Pulse Splitting in Volume Grating
Chen Piaoran, Yan Xiaona, Wang Yan, Dai Ye, Yang Xihua, and Ma Guohong
Based on the modified coupled-wave equations of Kogelnik, the dynamical diffraction properties, energy oscillation and pulse splitting of a sinusoidal volume holographic grating (VHG) illuminated by a femtoscond pulse with respect to the grating parameters and readout pulse parameters are studied. Result shows that theBased on the modified coupled-wave equations of Kogelnik, the dynamical diffraction properties, energy oscillation and pulse splitting of a sinusoidal volume holographic grating (VHG) illuminated by a femtoscond pulse with respect to the grating parameters and readout pulse parameters are studied. Result shows that the refractive index modulation of VHG and central wavelength of the readout pulse will affect the energy oscillation period, while the grating period has no effect on the energy oscillation period, but it will affect the angle between the line connected by centers of diffracted wave packets and the time axis. Based on group velocity and group delay, explanations on these phenomena are given. In the latter stage, diffracted pulse splits into two pulses, the pulse interval between them depends on the thickness and refractive index modulation of the VHG, and independent of the grating period, we explain it with the localization property of light field propagation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 105002 (2016)
High-Precision Alignment Technique with Large Measurement Range Based on Composite Gratings
Si Xinchun, Tang Yan, Hu Song, Liu Junbo, Cheng Yiguang, Hu Tao, Zhou Yi, and Deng Qinyuan
In order to meet the demands of high-accuracy alignment with large measurement range in proximity lithography, a method based on composite gratings is introduced. The composite gratings consist of small-period gratings with slightly different periods and large-period gratings with small range which are orthogonal to thIn order to meet the demands of high-accuracy alignment with large measurement range in proximity lithography, a method based on composite gratings is introduced. The composite gratings consist of small-period gratings with slightly different periods and large-period gratings with small range which are orthogonal to the smallperiod ones. Fine alignment is realized by high-precision phase analysis on moiré fringes while coarse alignment is achieved by obtaining the position of large-period gratings directly. Since the different-direction gratings are orthogonal to each other, there will be no influence on extracting frequency spectrum by applying Fourier transform. By analyzing the phase variations of small gratings’moiré fringes and the intensity of large-period gratings, substrate and mask can be aligned with high accuracy and large measurement range. Furthermore, the relation between the offsets of substrate and mask and the position changes of the two composite gratings are derived. An analysis of the built model is performed via simulation to show that the accuracy can reach 16.5nm while considering the noises; and an experiment is also conducted to verify the effectiveness of the proposed method and the accuracy can reach 30.19 nm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 105003 (2016)
Fiber Optics and Optical Communications
High Precision Identification of Optic Fiber Invasion Sensor Networks Information Based on the BBS and BPNN-DS Algorithm
Zhang Yanjun, Liu Wenzhe, and Fu Xinghu
Because of the cross sensitivity and other uncontrollable factors, the information data appear abnormal and result in the large deviation of information analysis and low recognition accuracy when using traditional monochannel optical sensing fiber to achieve the measurement. A feature extraction and recognition method Because of the cross sensitivity and other uncontrollable factors, the information data appear abnormal and result in the large deviation of information analysis and low recognition accuracy when using traditional monochannel optical sensing fiber to achieve the measurement. A feature extraction and recognition method based on bicoherence spectrum, sample entropy and singular value decomposition (BSS) and back propagation neural network (BPNN)-Dempster Shafer(DS) is proposed. Assuming the intrusion detection system contains three optic sensing fibers based on the Brillouin optical time domain reflection (BOTDR), the method utilizes the BSS algorithm to extract the different intrusion features of multiplex signal, respectively. The classification of the feature vectors for different intrusion vibrations is realized by using the BPNN algorithm and the spatio-temporal information fusion of multi sensing fibers is acquired by Dempster Shafer (DS) evidence theory. Numerical analysis and simulation results show that the novel method can effectively extract the information characteristics of multi-channel sensor networks and have higher accuracy and credibility based on BPNN-DS evidence theory compared with the monochannel optical sensing fiber. This multi-channel information fusion algorithm can also identify signal types of multiintrusion sensor networks accurately..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 106001 (2016)
High-Resolution Distributed Optical-Fiber Sensing Techology Based on Direct-Detecting Coherent Optical Time-Domain Reflectometer
Feng Kaibin, Song Muping, Xia Qiaolan, Lu Yan, and Yin Cong
A high-performance quantitative detection distributed optical fiber sensing technology based on Rayleigh scattering is proposed and studied. Based on the phase-sensitive optical time-domain reflectometer (Φ -OTDR), a direct detection coherent optical time-domain reflectometer (COTDR) sensing system is set up, by combinA high-performance quantitative detection distributed optical fiber sensing technology based on Rayleigh scattering is proposed and studied. Based on the phase-sensitive optical time-domain reflectometer (Φ -OTDR), a direct detection coherent optical time-domain reflectometer (COTDR) sensing system is set up, by combining the narrow-linewidth laser with microwave electro-optical modulation to obtain optical frequency-shift precisely. The sensing quantity (temperature or strain) can be obtained from the change of the Rayleigh scattering light interference pattern generated by the frequency shift of the light source. The sensing principle of the direct-detecting COTDR system is studied, with simulating and analyzing the COTDR sensing process and the correlation characteristics of the scattering signals. On the basis of theoretical analysis, the direct- detecting COTDR experimental system is built, and 25 km distributed optical fiber temperature sensing experiment is realized. The experiment results show that the COTDR experimental system can measure the temperature change of 0.1 ℃ at the end of the 25 km sensing fiber..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 106002 (2016)
Fabrication and Characterization of Big-Bore Flexible Dielectric-Coated Metallic Terahertz Waveguides
Li Yiqing, Tan Zhiyong, Cao Juncheng, Tang Xiaoli, and Shi Yiwei
Big-bore and flexible waveguides are fabricated for Terahertz wave transmission based on the structure of dielectric-coated metallic hollow waveguides.The liquid-phase coating technique for the dielectric film innercoating is modified and improved for the large-bore waveguides. The dielectric film thickness and the losBig-bore and flexible waveguides are fabricated for Terahertz wave transmission based on the structure of dielectric-coated metallic hollow waveguides.The liquid-phase coating technique for the dielectric film innercoating is modified and improved for the large-bore waveguides. The dielectric film thickness and the loss spectrum are the oretically and experimentally discussed. The experimental system is established to evaluate the transmission loss, additional bending attenuation, and output beam profile of the Terahertz (THz) waveguides at the frequency of 2.5 THz. According to the measured results, the transmission loss and additional bending attenuation are both decreased as the dielectric film thickness increases in the THz waveguides, while the energy distribution of beam profiles tends to focus on lower transmission modes..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 106003 (2016)
Design of a Spherical Optical Zoom Antenna Using for Mobile Visible Light Communication
Zhang Xuebin, Tang Yi, Cui Lu, and Bai Tingzhu
As the problem of the complex optical communication environment and the boundedness of the traditional optical antenna, an optical zoom antenna is designed for mobile visible light communication.The thickness of the antenna is reduced by using right-angle reflecting prism folding the space optical path. The surface typAs the problem of the complex optical communication environment and the boundedness of the traditional optical antenna, an optical zoom antenna is designed for mobile visible light communication.The thickness of the antenna is reduced by using right-angle reflecting prism folding the space optical path. The surface type of each lens in the antenna is spherical, which can save the system cost. The simulation results indicate that the zoom ratio of the system is 2.5; the field of view (FOV) can change between 16° and 42°; the system gain is 16.2; the system size is 18 mm×6 mm. The image quality of the system is well and the relative illumination is high, basically satisfying the communication application. At last, an indoor visible light communication system model is set up in a room with a size of 5 m×5 m×3 m, and the comparation of the detection results between the zoom antenna and the fixed-focus antenna in different situations is analyzed. The simulation results indicate that the optical zoom antenna can satisfy the requirement of large field of view and high gain, improve the system stability, mobility and environmental suitability, and be suitable for visible light communication..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 106004 (2016)
Theoretical Analysis for Long-Period Fiber Grating Strain Sensor Based on Dual-Peak Resonance near PMTP
Gu Zhengtian, and Ling Qiang
A novel long- period fiber grating (LPFG) strain sensor is presented, which is based on dual- peak resonance combined with high sensitivity of LPFG nearby phase-matching turning point (PMTP). The dual-peak resonant characteristics near PMTP and strain sensing properties of LPFG are analyzed firstly by phase-matching coA novel long- period fiber grating (LPFG) strain sensor is presented, which is based on dual- peak resonance combined with high sensitivity of LPFG nearby phase-matching turning point (PMTP). The dual-peak resonant characteristics near PMTP and strain sensing properties of LPFG are analyzed firstly by phase-matching condition of LPFG. It is found that dual-peak wavelength spacing has high response and linearity on small strain. Then, the influence of grating structure parameters and cladding diameters on sensitivity of dual-peak based LPFG is discussed and it is found that the grating periods affect the sensitivity, linearity and the range of strain. And the grating lengths have a valid influence on the peak and width,which directly concerns the precision of peek-peak. The results show that the sensitivity could effectively be improved by two orders of magnitude compared with that of the conventional LPFG strain sensor, if selecting the appropriate grating structure parameters and cladding radii. The research provides theoretical foundation for structural optimization of dual-peak resonant LPFG strain sensors with high sensitivity..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 106005 (2016)
Imaging Systems
Dual Mode Imaging of All-Optical Non-Contact Photoacoustic Tomography and Optical Coherence Tomography
Xie Bingkai, Liu Shaojie, Wu Yongbo, and Tang Zhilie
University, Guangzhou, Guangdong 510006, China Abstract A new dual-mode imaging method of all-optical non-contact photoacoustic tomography (ncPAT) imaging and optical coherence tomography (OCT) is presented to get absorption and scattering of sample simultaneously. An all-optical ncPAT-OCT dual-model imaging system is University, Guangzhou, Guangdong 510006, China Abstract A new dual-mode imaging method of all-optical non-contact photoacoustic tomography (ncPAT) imaging and optical coherence tomography (OCT) is presented to get absorption and scattering of sample simultaneously. An all-optical ncPAT-OCT dual-model imaging system is built. The same probe light and the same interferometer system are used to improve the stability of system. Synchronous trigger mode is utilized to ensure the data acquisition at the same time, and a common sample arm is employed to ensure the sampling region in the same space. On the basis of these, the images of PAT and OCT are achieved at the same time for the same sample. Experimental results show that the two-mode imaging can be a good match, and it can get different information in different modes..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 111001 (2016)
Parameters Design for Single Viewpoint Infrared Omnidirectional View Sensors
He Yu, Wang Lingxue, Zhou Xingguang, Cai Yi, Wei Shengyi, Xue Wei, Liu Fuping, Li Maozhong, and Chen Ji
A method of parameters design and optimization for single viewpoint infrared catadioptric omnidirectional imaging system to obtain sharp image for the whole field of view (FOV) by single shot is proposed. The initial system parameters are designed to meet single viewpoint constraint according to the application requireA method of parameters design and optimization for single viewpoint infrared catadioptric omnidirectional imaging system to obtain sharp image for the whole field of view (FOV) by single shot is proposed. The initial system parameters are designed to meet single viewpoint constraint according to the application requirements. A concept of virtual depth of field in mirror is proposed to optimize refracted optical group parameters. The proposed method is verified by simulation results using the ideal system of software ZEMAX. Using the method can not only obtain sharp image for the whole FOV, but also meet the requirements like FOV and axial dimension. The simulation results also show that large diameter mirror helps to improve the quality of the image and large surface eccentricity helps to reduce the axial dimension..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 111002 (2016)
Error Analysis and Eliminate Methods for Wavefront Detection Based on Phase Diversity Algorithm
Yue Dan, Xu Shuyan, Nie Haitao, Ma Hongcai, and Liu Nannan
Aimed at the error problems during practical engineering applications of wavefront detection based on phase diversity method when additional aberration is away from the focus mode, the impacts of these errors on the wavefront detection accuracy have carried on the quantitative analysis by taking the co- phasing of the Aimed at the error problems during practical engineering applications of wavefront detection based on phase diversity method when additional aberration is away from the focus mode, the impacts of these errors on the wavefront detection accuracy have carried on the quantitative analysis by taking the co- phasing of the segmented telescope are analyzed as an example, including focal plane position error, uncertainty of defocus amount, image alignment error, exposure delay and image noise. The method is presented to eliminate these impacts through modifying the phase diversity algorithm, the root mean square errors drop from 0.06λ,0.0581λ,0.0754λ,0.0796λ, 0.0737λ down to 5.8834 × 10-4 λ,6.664 × 10-4λ,3.5853 × 10-5 λ,6.1837 × 10-5 λ,0.0013λ respectively after correction, and the wavefront detection accuracies are still maintained in the same order of magnitudes as above even when errors are in a quite large range. The results show that the proposed method can effectively eliminate the errors, vastly improve the wavefront detection accuracy and has guiding significance for the usage of phase diversity wavefront detection technology in practical engineering..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 111003 (2016)
Correspondence Ghost Imaging via Photon Counting Based on Digital Micromirror Device
Cao Fei, Shi Jianhong, Yang Ying, and Zeng Guihua
The correspondence ghost imaging scheme via photon counting based on micromirror device is proposed. In this scheme, a digital micromirror device is used to module the light source, the time-correlated single photon counting technology is introduced to acquire the photon counting value, and correspondence ghost imagingThe correspondence ghost imaging scheme via photon counting based on micromirror device is proposed. In this scheme, a digital micromirror device is used to module the light source, the time-correlated single photon counting technology is introduced to acquire the photon counting value, and correspondence ghost imaging is used to calculate the image of target object. The principle of correspondence ghost imaging via photon counting is clarified with ghost imaging theory and correspondence ghost imaging theory, and the proposed scheme is verified by experiments. The research results show that the proposed scheme can realize weak light imaging. The images achieved by the proposed scheme are as good as those by traditional ghost imaging while the computational complexity in the process of image reconstruction is reduced. Besides, the measurement of intensity distribution by array detector is omitted in the proposed scheme and the image of target object is acquired with a single photon detector which has no spatial resolution, combined with correspondence ghost imaging algorithm. In the meantime, the proposed scheme can provide distance information of the object..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 111004 (2016)
Optimization Design for the Shapes of Cold Shield in Infrared Systems
Jin Ning, Yang Kaiyu, Cao Ling, and Ming Jingqian
The cold shield mismatches exit pupil in simple imaging infrared optical systems, causing the interference in the systems. For those systems, optimization design for the shapes of cold shield is necessary to suppress the stray light. A mathematical method using optimization calculation to design the shapes of cold shieThe cold shield mismatches exit pupil in simple imaging infrared optical systems, causing the interference in the systems. For those systems, optimization design for the shapes of cold shield is necessary to suppress the stray light. A mathematical method using optimization calculation to design the shapes of cold shield is proposed. The mathematical models of optimization variables and objective functions are established, then global optimization by the interval exhaustive method and local optimization by the damped least squares method are combined to obtain a proper cold shield shape. The method built in the article is used to design the shape of cold shield for an existing thermal imaging optical system. The problems of stray light in the system caused by the mismatch of cold shield and exit pupil are solved, and thus the method built to optimization design for the shapes of cold shield is proved to be positive and applicable..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 111005 (2016)
Source Mask Optimization Based on Dynamic Fitness Function
Yang Chaoxing, Li Sikun, and Wang Xiangzhao
A dynamic source mask optimization (SMO) method is developed. The dynamic SMO method uses a dynamic fitness function in genetic algorithm to simulate the process variations in real lithography process. So the imaging quality of the optimized source and mask is not sensitive to the process errors. The dynamic SMO methodA dynamic source mask optimization (SMO) method is developed. The dynamic SMO method uses a dynamic fitness function in genetic algorithm to simulate the process variations in real lithography process. So the imaging quality of the optimized source and mask is not sensitive to the process errors. The dynamic SMO method can get similar result as the conventional weighted SMO method without the necessity of weighting coefficient optimization. Simulation results show that the dynamic method can get a usable defocus of 200 nm when the dose error is 15%. This is comparable with the optimized result of the weighted method. The dynamic SMO method can be also used to make the optimized source and mask less sensitive to other process errors, such as coma errors..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 111006 (2016)
Instrumentation, Measurement and Metrology
Absolute Displacement Measurement with Point-Diffraction Interferometer Based on Quick Searching Particle Swarm Optimization Algorithm
Wang Daodang, Xu Yangbo, Chen Xixi, Guo Tiantai, Kong Ming, Zhao Jun, and Zhu Baohua
To enhance the convergence ratio, timeliness and accuracy of current iterative algorithm in the measurement of three dimensional absolute displacements with point-diffraction interferometer (PDI), the method based on quick searching particle swarm optimization (QS-PSO) algorithm is proposed for the reconstruction of abTo enhance the convergence ratio, timeliness and accuracy of current iterative algorithm in the measurement of three dimensional absolute displacements with point-diffraction interferometer (PDI), the method based on quick searching particle swarm optimization (QS-PSO) algorithm is proposed for the reconstruction of absolute displacements. The three dimensional absolute displacement of the probe is determined from the distribution of the phase difference in the interference field. To realize the efficient procession of a large number of sampling pixel points, the sampling points are nonlinearly increased in the process of iteration in the proposed QS- PSO method, by which both the high- efficiency and high- precision measurement are achieved. Both the computer simulation and experimental measurements are carried out to verify the feasibility of the measurement. According to the analyzing results, the convergence rate and measurement precision of the proposed measurement method can reach 90% and better than the order of microns within a 200 mm×200 mm×300 mm working volume, respectively. The proposed absolute displacement measurement method is of high efficiency, measurement precision, anti-noise ability and reliability, and also of great significance for the application of micro-processing and high precision measurement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 112001 (2016)
Aberration Measurement Method for Hyper-NA Lithographic Projection Lens
Zhu Boer, Wang Xiangzhao, Li Sikun, Yan Guanyong, Shen Lina, and Duan Lifeng
An aberration measurement method for hyper-NA lithographic projection lens by use of aerial image based on principal component analysis is proposed. Aerial images of the hyper-NA lithographic projection lens are expressed accurately by using polarized light and vector imaging model, as well as considering the polarizatAn aberration measurement method for hyper-NA lithographic projection lens by use of aerial image based on principal component analysis is proposed. Aerial images of the hyper-NA lithographic projection lens are expressed accurately by using polarized light and vector imaging model, as well as considering the polarization properties. As a result, the accuracy of the measurement model is improved and the aberrations of hyper- NA lithographic projection lens are measured accurately. Compared with the conventional AMAI-PCA method, the proposed method is applicable for the hyper-NA lithographic projection lens. The lithographic simulator PROLITH is used to validate the accuracies of aberration measurement and analyze the impacts of the sample interval of aerial images on the accuracy of the aberration measurement. The result shows that the proposed method can retrieve 33 terms of Zernike coefficients (Z5~Z37) with maximum error less than 0.85×10-3λ..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 112002 (2016)
Suppression of Nonlinear Frequency Sweep in Frequency Sweeping Interferometer Based on Order Tracking Technique
Liu Zhe, Liu Zhigang, Deng Zhongwen, and Tao Long
A new method based on order tracking technique for reducing the effect of nonlinear optical frequency swept in frequency sweeping interferometer(FSI) is presented. The main factors affecting the measuring accuracy of the FSI system are discussed in frequency domain. This method utilizes the optical resonant characterisA new method based on order tracking technique for reducing the effect of nonlinear optical frequency swept in frequency sweeping interferometer(FSI) is presented. The main factors affecting the measuring accuracy of the FSI system are discussed in frequency domain. This method utilizes the optical resonant characteristic of a Fabry-Perot etalon to measure the instantaneous optical frequency of a laser rapidly. Carries on the data linear fitting to the optical frequency on the least- square method and make the slope of the linear equation as the correction rate of optical frequency. The time series of equidistant optical frequency grid can be obtained with polynomial fit and interpolation of optical frequency. The interference signal can be resampled according to time series of equidistant optical frequency grid, and then reconstructed by using data interpolation. The frequency value of non-stationary interference signal is achieved after spectral analysis of reconstructed interference signal. The results indicate that this method dramatically reduces the effects of the nonlinear sweep without limit the range of the measured distance, and demonstrates spatial resolution enhancement of more than 36 times in the range of 1000 mm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 112003 (2016)
Theoretical Analysis of Arbitrary and Absolute Length Measurement by Using Femtosecond Optical Frequency Comb
Zhuge Jingchang, Xing Shujian, and Gao Jianshu
In order to solve the problem of the difficulties in obtaining consecutive values by the pulse interferometry method, a method of multiple pulse interferometry by using femtosecond optical frequency comb is proposed for the arbitrary and absolute length measurement with high precision. The main principle of the arbitraIn order to solve the problem of the difficulties in obtaining consecutive values by the pulse interferometry method, a method of multiple pulse interferometry by using femtosecond optical frequency comb is proposed for the arbitrary and absolute length measurement with high precision. The main principle of the arbitrary and absolute length measurement on the basis of multiple pulse interferometry is expounded, and then the temporal correlation model of multiple pulse train interference fringes is constructed. The peak position shift which can contribute to the distance is analyzed. The effect of dispersion on the correlation fringes is also analyzed. In addition, the effects of the atmosphere environmental variations including temperature, humidity, air pressure, and CO2 content on the air refractive index, which affects the measuring precision, are simulated. The simulation results show that the shift of the peak position of the multi-pulses interference fringes is periodic and monotonous in a period. The change of temperature and humidity is proportional to the change of the peak distance of the multipulse interference fringes，while the change of air pressure and CO2 content is in opposite..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 112004 (2016)
Integrated Optics
Crosstalk Analysis of Optical Switching Chips with DQPSK Signal Transmission Experiment
Zhao Yuanli, Wu Baojian, Liao Mingle, Geng Yong, and Qiu Kun
Crosstalk and insertion loss are two important parameters for optical switching integrated chips. A new theoretical model of crosstalk in optical switching integrated chips, which is dependent on insertion loss and switch routing states, is put forward. As an example, the crosstalk and insertion loss coefficients of thCrosstalk and insertion loss are two important parameters for optical switching integrated chips. A new theoretical model of crosstalk in optical switching integrated chips, which is dependent on insertion loss and switch routing states, is put forward. As an example, the crosstalk and insertion loss coefficients of the optical switching integrated chip consisting of Mach-Zehnder interferometer (MZI)-based 4×4 Benes structure are measured by the 40 Gb/s differential quadrature phase shift keying (DQPSK) experiment under different switch routing states. The experimental results are consistent with the theoretical analysis. The crosstalk range for the16×16 Benes-type optical switching chips is calculated according to the given crosstalk and insertion loss coefficients..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 113001 (2016)
Lasers and Laser Optics
Study on Propagation Characteristics of Laser Quads in Cylindrical Hohlraum for Indirect Drive Facility
Wen Ping, Li Zelong, Zhong Zheqiang, and Zhang Bin
In inertial confinement fusion facilities, the propagation characteristic of laser quads in the cylindrical hohlraum is especially important for achieving the effective compression of target. In order to understand the irradiation characteristics of laser quads in hohlraum, the propagation model of laser quads in vacuuIn inertial confinement fusion facilities, the propagation characteristic of laser quads in the cylindrical hohlraum is especially important for achieving the effective compression of target. In order to understand the irradiation characteristics of laser quads in hohlraum, the propagation model of laser quads in vacuum cylindrical hohlraum for the typical structure and beam configuration has been built up. The propagation characteristics of multiple laser quads have been numerically simulated. Considering the crossing beam energy transfer and laser plasma interaction caused by laser quads overlapping and crossing, the method for determining the characteristic plane where laser quads separate with each other in cylindrical hohlraum has been proposed, and the propagation and overlapping characteristics of the quads from the aspects of polarization characteristics and fractional hot spots have been further analyzed. The results show that during the propagation of multiple quads in cylindrical hohlraum, the inner cone and outer cone separate initially, followed by the separation of adjacent laser quads of both the inner cone and outer cone. When all quads for a single laser entrance hole propagating inside cylindrical hohlraum, the irradiation uniformity of the superposition spots first degrades and improves, then degrades again while propagating from the laser entrance hole to the wall, but peak intensity of hot spots degrades with the increasing of the defocusing distance，and the proportion of hot spots first increases and degrades. In addition, the polarization degree of the multiple laser quads remains almost unchanged during the propagation in hohlraum..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 114001 (2016)
Output Characteristics of Q-Switched Mid-Infrared Fiber Laser with a Mechanical Chopper
Shen Yanlong, Zhou Songqing, Chen Hongwei, Huang Ke, Luan Kunpeng, Tao Mengmeng, Yu Li, Yi Aiping, and Feng Guobin
A high power actively Q-switched mid-infrared fiber laser at 2.8-μm waveband is demonstrated by employing a 975 nm laser- diode pumping a piece of heavily Er3 +- doped ZBLAN doubleclad fiber and a mechanical chopper into the cavity as the Q- switch. Output characteristics at different pump powers and various repetitionA high power actively Q-switched mid-infrared fiber laser at 2.8-μm waveband is demonstrated by employing a 975 nm laser- diode pumping a piece of heavily Er3 +- doped ZBLAN doubleclad fiber and a mechanical chopper into the cavity as the Q- switch. Output characteristics at different pump powers and various repetition rates is investigated. Meanwhile, the pulse spikes are observed and analyzed. The maximum pulse energy of 84.5 μJ, pulse duration of 250.3 ns and peak power of exceeding 300 W is obtained at a repetition rate of 3.5 kHz under a proper pump power..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 114002 (2016)
Machine Vision
Long-Term Visual Tracking Based on Spatio-Temporal Context
Liu Wei, Zhao Wenjie, and Li Cheng
Aiming at the tracking drift problem due to object model update falsely in the online learning tracking algorithms, a simple but efficient solution is proposed. In the target area point trackers are uniformly sampled, which are assessed based on texture description in two consecutive frames point trackers and then the Aiming at the tracking drift problem due to object model update falsely in the online learning tracking algorithms, a simple but efficient solution is proposed. In the target area point trackers are uniformly sampled, which are assessed based on texture description in two consecutive frames point trackers and then the initial location of target is completed. Multi-dimensional feature spatio-temporal context model is used to output the precise position of object by the confidence map, the model update rate is decided combining with the confidence map and a multiscale update mechanism is proposed. Experimental results show that the proposed algorithm can complete the robust tracking under the condition of background interference, fast motion, occlusion, illumination changing and scale changing. In the video sequence of 320 pixel×240 pixel, the average tracking speed can keep in 55.1 frame/s, which meets real-time application requirement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 115001 (2016)
Solution of Duality in Pose Estimation of a Single Circle Utilizing Constraint Angles Motion Reconstruction
Zhang Lijun, Huang Xuexiang, Feng Weichun, Hu Tianjian, and Liang Shuli
In order to cope with the pose duality problem in the visual measurement of a single circle, a disambiguating approach is proposed utilizing constraint angles motion reconstruction. On the premise of camera calibrated, the pose parameter of a circle is estimated from its projected ellipse curve but the pose has dualityIn order to cope with the pose duality problem in the visual measurement of a single circle, a disambiguating approach is proposed utilizing constraint angles motion reconstruction. On the premise of camera calibrated, the pose parameter of a circle is estimated from its projected ellipse curve but the pose has duality. The world coordinates of feature points are recovered by the method of multiple view structure from motion and constraint angels are reconstructed with feature points. Based on the nature that rigid body motion does not change space angles, the poses of multiple view are determined simultaneously. Experimental results indicate that within the range of 500 mm the circle radius, the success rate of eliminating false solution is up to 100% when the noise level is within 0.4 pixel and 93% when the noise level is 1 pixel. And the success rate is 99.6% when the noise level is 0.1 pixel and the range is 1000 mm the circle radius. Besides, the average run time of the proposed algorithm in two views is about 5 ms which suits real-time application. The proposed approach can effectively identify real poses of a single circle in real time without any additional information of target..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 115002 (2016)
Large Field and Binocular Vision Calibration Algorithm Based on Position and Orientation Constraints
Zhang Chao, Han Cheng, Yang Huamin, and Yang Fan
In order to improve the accuracy of large field, far distant binocular camera calibration, a new calibration algorithm based on the constraints of camera position and orientation is proposed. As the three-dimensional position and orientation relationship between binocular cameras is a rigid transformation, the externalIn order to improve the accuracy of large field, far distant binocular camera calibration, a new calibration algorithm based on the constraints of camera position and orientation is proposed. As the three-dimensional position and orientation relationship between binocular cameras is a rigid transformation, the external parameters of relative pose of left and right cameras are targeted. By using the constraints of the relative position and orientation, internal parameters of the initial left and right cameras are calibrated. Excluding calibration image groups by large reprojection errors, repeating iterations until the mean of re-projection errors is less than the specified value, several camera internal parameters to be optimized is obtained. Then combining with the corner point coordinates of image groups, camera internal parameters to be optimized and corresponding external parameters, an objective function is established that the values of three-dimensional reconstruct corner point coordinates and the values of the actual three-dimensional corner point coordinates are the smallest. The optimal solution of binocular camera calibration parameters is solved. The proposed method is a good solution to the impact caused by the large error of calibration image, and makes full use of the constraint relationship between the binocular cameras position and orientation. Through simulation and calibration experiments, it can be seen that the proposed method can achieve a high precision calibration of large field binocular cameras..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 115003 (2016)
Materials
Aluminum Surface Morphologies and Optical Properties of Al/Al2O3 Composite Ceramic Substrate for White LEDs
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The bonding of aluminum film with coated copper alumina substrate is realized by brazing technology. The new type Al/Al2O3 composite ceramic substrate with high thermal conductivity is successfully prepared. Mechanical polishing, chemical polishing and electrolytic polishing methods are carried out for aluminum film poThe bonding of aluminum film with coated copper alumina substrate is realized by brazing technology. The new type Al/Al2O3 composite ceramic substrate with high thermal conductivity is successfully prepared. Mechanical polishing, chemical polishing and electrolytic polishing methods are carried out for aluminum film polishing on the surface of composite substrate. Research results show that all of these polishing methods can improve the aluminum film surface roughness and enhance the reflective rate of aluminum film. Moreover, the sample processed by chemical and electrolytic polishing method has the lowest surface roughness and highest reflective rate compared with other polishing methods..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 116001 (2016)
Medical Optics and Biotechnology
Dual Modulation Optical Polarimetry for Glucose Monitoring
Yu Zhenfang, Qiu Qi, and Guo Yong
Optical polarimetry for probing aqueous humor glucose concentrations has been shown as a method for ascertaining blood glucose concentrations noninvasively. One major limiting factor for polarimetric approach for glucose sensing is time-variant corneal birefringence due to motion artifact. A real-time closed-loop singlOptical polarimetry for probing aqueous humor glucose concentrations has been shown as a method for ascertaining blood glucose concentrations noninvasively. One major limiting factor for polarimetric approach for glucose sensing is time-variant corneal birefringence due to motion artifact. A real-time closed-loop single wavelength polarimetric glucose sensor is designed utilizing modulation of laser simultaneously with Faraday modulation. The method overcomes the problem of previous polarimetric systems whose response speed is solely limited by the Faraday modulation frequency, when the lasers are powered by a constant direct-current voltage and the polarization is modulated using a single Faraday rotator. It makes the feedback system reach stable status within 10 ms, which should be fast enough to minimize the effect of polarization rotation due to birefringence. This approach can reduce laser noise from 1/f in addition to electromagnetic interference, improving the signal-to-noise ratio of the system at the presence of motion artifact. The system is constructed and evaluated in vitro for glucosedoped water solutions, whose concentrations are 0~600 mg/dL with increment of 100 mg/dL, the standard error of predicted results of glucose concentration is less than 10 mg/dL, demonstrating the repeatability and accuracy of the system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 117001 (2016)
Optical Design and Fabrication
Theoretical Analysis and Design of Bi-Directional Anisotropic Fisheye Lens
Chen Chen, Hu Chunhai, Li Weishan, and Liu Xiaochan
In order to improve the pixel utilization rate of single projector dome movie system constructed by fisheye lens, the design concept of bi-directional anisotropic digital fisheye projection lens is proposed. By analyzing the characteristics of cylindrical lens, the function relationship of astigmatism and the focal lenIn order to improve the pixel utilization rate of single projector dome movie system constructed by fisheye lens, the design concept of bi-directional anisotropic digital fisheye projection lens is proposed. By analyzing the characteristics of cylindrical lens, the function relationship of astigmatism and the focal length of cylindrical lens is given, and the focal length distribution relationship in sagittal direction and meridian direction is given. The structure of bi-directional digital fisheye projection lens is analyzed and designed, and gradual changing focal lengths along dimensions are produced by introducing cylindrical lens in lens structure. The lens have different image heights in sagittal direction and meridian direction at the same field of view, finally, the anisotropic mapping law is formed. The optical system of lens contains four sagittal cylindrical surfaces and one meridian cylindrical surface, the ratio of the sagittal image height to the meridian image height is 1.52∶1, with high resolution. Compared with the traditional fisheye lens, the pixel utilization rate of the single projector digital dome screen system constructed by the bidirectional anisotropic digital fisheye projection lens is increased by 52%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 122001 (2016)
Study on Optical Efficiency Characteristics of Receivers in a Solar Parabolic Trough Concentrator
Feng Zhikang, Li Ming, Wang Yunfeng, Chen Fei, Ji Meng′en, and Hong Yongrui
Optical efficiency differences between the evacuated tube receiver and a triangular cavity receiver are theoretically analyzed. Furthermore, the calculation expressions of the critical installation position for the optimal effective absorptivity of the cavity receiver are given, which is validated through TracePro softOptical efficiency differences between the evacuated tube receiver and a triangular cavity receiver are theoretically analyzed. Furthermore, the calculation expressions of the critical installation position for the optimal effective absorptivity of the cavity receiver are given, which is validated through TracePro software simulation. Simulation results show that the optical efficiency of cavity receiver can reach 89.1%, while the evacuated tube′ s efficiency is 77.1%. Meanwhile, the installation position deviations in the vertical or parallel direction have similar impacts on efficiencies of both receivers, but the cavity′s efficiency curve is slightly asymmetrical, which indicates that the best vertical installation position is 5~20 mm below focal length. It is also observed that mirror deflection error has greater influence on receiver efficiency, and the deflection angle should be controlled within 0.4°. Beyond this range, the descend degree of cavity receiver efficiency is less than the evacuated tube, which is confirmed by experimental test results. In addition, the thermal efficiencies of both receivers would meet at equilibrium point of 55.0%, in the case of ideal installation condition and heat collecting temperature of 168.6 ℃. Below this critical temperature, cavity receiver has a higher efficiency..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 122002 (2016)
Optical Design of Miniature Spectrometer Based on ZnSe Planar Waveguide
Li Yangyu, Fang Yonghua, and Li Dacheng
Common method of spectrometer miniaturization is implemented by decreasing the size of optical components and the distance between them, which will reduce the system performance. In order to achieve high throughput, high spectral resolution infrared spectral detection, a design method of a miniature spectrometer based Common method of spectrometer miniaturization is implemented by decreasing the size of optical components and the distance between them, which will reduce the system performance. In order to achieve high throughput, high spectral resolution infrared spectral detection, a design method of a miniature spectrometer based on ZnSe planar waveguide is proposed. First, the principle of beam compression by planar waveguide is described. Then, in accordance with the diffraction properties of grating in ZnSe medium, the relationship between the spectral resolution and the various optical parameters is deduced. Finally, a specific design of a miniature spectrometer is given. The spectral range of this spectrometer is 8~14μm, the spectral resolution is 80 nm, numerical aperture is 0.3. The optical system is a monolithic ZnSe planar waveguide, the size is 70 mm×70 mm×4 mm. A comparison between this spectrometer and common Czerny-Turner of the same design specifications is done. The results show that miniature spectrometer based ZnSe planar waveguide has very small size, good spectral resolution and high throughput..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 122003 (2016)
Optical Devices
Thermal Analysis of AlGaInP-Based LED Microarray
Li He, Liang Jingqiu, Liang Zhongzhu, Tian Chao, Qin Yuxin, Lü Jinguang, and Wang Weibiao
The accumulated heat of light emitted diode (LED) microarray chip at work will result in an excessive junction temperature, which causes a series of adverse effects on the LED microarray chip, severely reduce the reliability of LED microarray chip and even cause permanent damage. Heat dissipation is a key factor that rThe accumulated heat of light emitted diode (LED) microarray chip at work will result in an excessive junction temperature, which causes a series of adverse effects on the LED microarray chip, severely reduce the reliability of LED microarray chip and even cause permanent damage. Heat dissipation is a key factor that restricts the improvement of working performance of LED microarray, making it an urgent problem to be solved in the manufacturing process of LED microarray chip. A finite element model of AlGaInP-based LED microarray has been built, and the way of modeling, meshing and applying of the boundary conditions has been introduced. Temperature distributions have been analyzed respectively when a single unit and 3×3 units are driven by a pulse current. In order to improve the heat dissipation performance of LED microarray, a structure of heatsink has been designed, the influence of the heatsink on temperature distribution of microarray has been analyzed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 123001 (2016)
Research on Tunable Filter Based on Micro-Ring Resonators
Wu Danning, Wu Yuanda, Wang Yue, An Junming, and Hu Xiongwei
Deep ultraviolet photolithography and inductively coupled plasma etching processes are adopted to fabricate the filters based on silicon-on-insulator micro-ring resonators, and the radius is only 5 μm. A fourchannel optical add-drop multiplexer based on single micro-ring is fabricated, and the size of the device is onlDeep ultraviolet photolithography and inductively coupled plasma etching processes are adopted to fabricate the filters based on silicon-on-insulator micro-ring resonators, and the radius is only 5 μm. A fourchannel optical add-drop multiplexer based on single micro-ring is fabricated, and the size of the device is only 3000 μm×500 μm. The test results show that the device can perfectly realize the upload and download functions. The free spectral range is about 19.6 nm and the maximum extinction ratio is 19.76 dB. Meanwhile, a reconfigurable optical add-drop multiplexer based on dual racetrack micro-ring resonator is optimally designed and fabricated. The adjacent crosstalks of the two kinds of optical add-drop multiplexer based on single micro-ring and dual racetrack micro-ring respectively are tested, and the maximum adjacent crosstalks are -11.94 dB and -20.04 dB, respectively. Because there is no cross-section between the add-drop channels and the backbone in dual racetrack optical add-drop multiplexer, the adjacent crosstalk is apparently less than the single micro-ring optical add-drop multiplexer. PIN junction modulator based on dual racetrack micro-ring resonators is designed and fabricated. When the added voltage reaches 1.6 V, the resonant peak has a blue shift of 0.78 nm, finally the test results are analyzed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 123002 (2016)
Optics at Surfaces
Study of Surface Plasmon Polariton Waveguide of Silver Nanowire
Zhang Xu, Wu Yu, Tong Xuan, Xu Xiaofang, and Lü Liu
A specific optical system is designed and implemented to study the surface plasmon polaritons waveguides of silver nanowire deposited on the indium tin oxide (ITO) substrate. Fiber optical taper is used to stimulatethe surface plasmon polaritons in the near field. The degree between the fiber optical taper and the silvA specific optical system is designed and implemented to study the surface plasmon polaritons waveguides of silver nanowire deposited on the indium tin oxide (ITO) substrate. Fiber optical taper is used to stimulatethe surface plasmon polaritons in the near field. The degree between the fiber optical taper and the silver nanowire is changed by a R axial rotation. The coupling efficiency of the silver nanowire waveguide is researched corresponding to the different intersection degrees. The charge couple device (CCD) digital pictures are caught and the inlet and outlet scattering intensities are calculated by the gray histogram tool in the Adobe Photoshop with a 100 pixel×100 pixel. According to the experimental results, the coupling efficiency is effected by the intersection degree between the fiber optical taper and the silver nanowire, and the value reaches the peak when the angle is 0° and reaches the minimum when the angle is 90°。.
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 124001 (2016)
Scattering
BRDF Model of Bare Surface over Rugged Terrain
Huang Xun, Bai Lu, and Wu Zhensen
A three-dimensional mesh model of rugged terrain is built based on the digital elevation model data. The average normal vector of each slope element is derived from its slope angle and aspect. Given the sun-view geometry in global system, the sun- view geometry of each slope element in local coordinate system can be caA three-dimensional mesh model of rugged terrain is built based on the digital elevation model data. The average normal vector of each slope element is derived from its slope angle and aspect. Given the sun-view geometry in global system, the sun- view geometry of each slope element in local coordinate system can be calculated through coordinate conversion. Considering the shadowing effect, a bidirectional reflectance distribution function (BRDF) model of bare surface over rugged terrain is established in visible and near-infrared band. The validation of the model in desert area is conducted. The effect of the degree of surface relief and solar zenith angle on the model is studied. The results show that the tendency of BRDF varying with viewing azimuth angle of different rugged terrains has characteristic asymmetric distribution. BRDF in near perpendicular plane is larger than that in near principal plane. BRDF of the same rugged terrain decreases with the increase of solar zenith angle. BRDF tends to be larger as the wavelength increases..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 129001 (2016)
Suppression Situation of Incoherent Superposition of Laser Beams on Speckle Noise
Deng Hui, Zhang Rongzhu, and Sun Nianchun
To suppress the distortion of speckle noise produced by laser illumination on image information in highspeed photography, the statistic characteristics of speckle noise are analyzed. Based on the statistic characteristics, incoherent superposition principle of laser beams to reduce noise is analyzed, specially when theTo suppress the distortion of speckle noise produced by laser illumination on image information in highspeed photography, the statistic characteristics of speckle noise are analyzed. Based on the statistic characteristics, incoherent superposition principle of laser beams to reduce noise is analyzed, specially when the average intensity of speckles is not identical and meets with different distributions. The contrast of speckle over the number of superposition speckles is discussed. The influence of the number of superposition speckles in different distributions of the average intensity of speckles on the contrast of speckle is simulated. The results indicate that, the contrast of speckle increases with the increase of the difference of the average intensity of speckle in superposition, leading to a worse suppression effect. And the theoretical results agree with the experimental results..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 129002 (2016)
Study of Energy Dispersive X-Ray Scattering Technique with Polycapillary X-Ray Optics for Identification of Sorts of Liquids
Wang Junling, Duan Zeming, Cao Jinhao, Liu Zhiguo, Pan Qiuli, Li Rongwu, and Cheng Lin
Energy dispersive X- ray scattering (EDXRS) technique is an effective method for identification of sorts of liquids. In this experiment, the polycapillary X-ray half optics is used to replace the slits of the EDXRS to identify the sorts of the liquid samples. The experimental results show that alignment system consistsEnergy dispersive X- ray scattering (EDXRS) technique is an effective method for identification of sorts of liquids. In this experiment, the polycapillary X-ray half optics is used to replace the slits of the EDXRS to identify the sorts of the liquid samples. The experimental results show that alignment system consists of the two polycapillary X- ray half optics can improve the efficiency of X- ray source and the resolution of the scattering spectrum. The EDXRS with polycapillary X-ray half optics is an appropriate method to identify the sorts and concentrations of liquids, and has a widely applications for the identification of sorts of liquids..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 129003 (2016)
Spectroscopy
Study of Fourier Transform Imaging Spectrometer with Wide Field of View
Zhang Zhinan, Li Libo, Hu Bingliang, and Feng Yutao
In order to meet the demand of wide field of view (FOV), wide swath width, and high throughput for the ocean spectrum，a new Fourier transform imaging spectrometer with wide FOV based on the image plane interference technologies presented. And the principle and expressions of the image plane interference are studied andIn order to meet the demand of wide field of view (FOV), wide swath width, and high throughput for the ocean spectrum，a new Fourier transform imaging spectrometer with wide FOV based on the image plane interference technologies presented. And the principle and expressions of the image plane interference are studied and educed.The optical system is designed and optimized based on the calculated detailed parameters. Dyson and double Gauss structures are used in the relay lens and fore optics respectively. Under the circumstance of 400~900 nm spectral range, 35.5o FOV, 320 km swath width, F/4, and 100 mm focal length, the average signal noise ratio (SNR) is greater than 100 and the modulation transfer function (MTF) of the current design is greater than 0.5 at 32 lp/mm. All the parameters are well satisfied by the present design..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 130001 (2016)
Detection Method of Marine Oil Spilling and Emulsified Oil Based on Hyperspectral Imaging under UV Induction
Han Zhongzhi, Wan Jianhua, Liu Yongping, Liu Kangwei, and Liu Jie
For the problem of oil spilling detection at night, a detection method based on band difference index of high spectral and ultraviolet(UV) LED induction is proposed. Through hyperspectral imaging collector, hyperspectral images of crude oil, emulsion oil and seawater obtained under UV LED and halogen lamp are collectedFor the problem of oil spilling detection at night, a detection method based on band difference index of high spectral and ultraviolet(UV) LED induction is proposed. Through hyperspectral imaging collector, hyperspectral images of crude oil, emulsion oil and seawater obtained under UV LED and halogen lamp are collected synchronously. The band difference index is extracted based on radiation values of 33 bands (400~720 nm)to act as the identification feature of oil spilling. In the respect of feature optimization, effective wavelengths are chosen by methods of plus L reduce R and Fisher. The band features are extracted by multidimensional scaling, principal component analysis (PCA) and independent component analysis. An radial basis function support vector machine model is established to recognize the results. The results show that the band mean recognition rates of oil spilling detection method based on UV-LED and hyperspectral band difference index are higher than halogen lamps by 6.01% and 8.17%. Therefore, UV-LED light source is more suitable for accurate detection of oil spilling and emulsified oil testing at night. The optimized method by Fisher as an effective wavelength selection and through the PCA feature combination effect have almost same recognition rate. Recognition rates of 3 bands characteristics under UV light attain to 85.89% and 87.02% , while the accuracy of oil spilling reaches 100% by 12 characteristics. Effective wavelengths (400~420 nm) extracted by Fisher are more suitable for actual online oil spill detection. The model of the UV induced by hyperspectral imaging sea spilling identification built provides a rapid identification method for the sea oil spills detection at night..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 130002 (2016)
Independent Component Feature Extraction Method for Hyperspectral Image Based on Negentropy Statistics in Moving Windows
Zhu Yuanyuan, Gao Jiaobo, and Gao Zedong
An independent component feature extraction method based on negentropy statistics in moving windows is presented for the ordering of the independent components, and applied in target detection. A small window is moved in the two dimensional space of the independent component image. Data from each window is evaluated byAn independent component feature extraction method based on negentropy statistics in moving windows is presented for the ordering of the independent components, and applied in target detection. A small window is moved in the two dimensional space of the independent component image. Data from each window is evaluated by negentropy approximation statistics using nonpolynomial function. The largest one of all of the evaluations is considered as the result evaluation, and the component images are ordered by the result evaluation. The two- value figure from the chosen component is made by histogram zero value split method, realizing target detection from the feature extracted independent components. The experiment results show that the independent component feature extraction method based on negentropy statistics in moving windows can avoid the influence of wild values, also select the valid components with small target, and benefit rapid detection of interested target..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 130003 (2016)
Analytic Study on Spectrum Characteristics of Oil Flame Based on Wavelet Decomposition
Liu Hongtao, Chen Zhili, Liu Qiang, Yin Wenqi, and Yang Yi
Due to the lack of adequate studies on the characteristics of infrared spectra of oil flame, an analytical study on flame spectra of various oil types and other combustible objects in outdoor space is carried out by establishing an all-flame infrared testing system with the spectral range of 1~14 mm. The results show tDue to the lack of adequate studies on the characteristics of infrared spectra of oil flame, an analytical study on flame spectra of various oil types and other combustible objects in outdoor space is carried out by establishing an all-flame infrared testing system with the spectral range of 1~14 mm. The results show that the signal of honeycomb briquette spectrum is the most special among all the spectra. After 5-layer decomposition of other fuel flame spectral signals by the db2 mother wavelet, low frequency components of 92# gasoline, 95# gasoline, 0# diesel oil, aviation kerosene and lube flame spectral features are similar and there exist strong emission peaks in the vicinity of 1.2, 3.4 and 4.5 mm. The 5th layer detail coefficients of various fuel oil flame are in line with each other. The low frequency components and the detail coefficients of 92# gasoline and 0# diesel oil flame spectra have obvious features compared with those of other fuels (wood, alcohol and paper). The experimental conclusion is of great significance in the detection and identification of oil flame based on spectral characteristic analysis..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 130004 (2016)
Thin Films
Model for Rapid Reverse Determination of the Refractive Index Bulk Inhomogeneity of Thin Films at Oblique Incidence
Jian Yudong, Tang Jianxun, Wu Suyong, and Tan Zhongqi
Bulk inhomogeneity of refractive index is a normal kind of film defects, the reverse determination of which can be vital for the design and manufacture of coatings. The characteristic matrix of inhomogeneous thin films is derived, and an approximation model for the spectral characteristics calculation of the thin filmsBulk inhomogeneity of refractive index is a normal kind of film defects, the reverse determination of which can be vital for the design and manufacture of coatings. The characteristic matrix of inhomogeneous thin films is derived, and an approximation model for the spectral characteristics calculation of the thin films at oblique incidence is presented using the matrix method. The calculation accuracy and time consumption of the presented approximation model are discussed in details. The effectiveness of the model is proved by calculating the ellipsometric angle. It turns out that the model for inhomogeneous films at oblique incidence presents a rapid and effective tool for the numerical optimization algorithm application into the data fitting of measured broadband spectral characteristics of actual multilayer coatings..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 1, 131001 (2016)
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