Contents
2017
Volume: 37 Issue 7
45 Article(s)
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Research on Atomic Phase Feedback in Pulsed Optically Pumped Atomic Clocks
Dong Gongxun, Lin Jinda, Zhang Song, Deng Jianliao, and Wang Yuzhu
In the atomic clocks based on the Ramsey process, the free evolution time cannot be very long which is limited by the coherent time of atoms and the phase noise of crystal oscillation. The non-destruction detection method with a large-detuning light is proposed. The atom phase data are obtained with this method and fedIn the atomic clocks based on the Ramsey process, the free evolution time cannot be very long which is limited by the coherent time of atoms and the phase noise of crystal oscillation. The non-destruction detection method with a large-detuning light is proposed. The atom phase data are obtained with this method and fed back to the microwave phase, which contributes to the realization of the atomic phase feedback and the effective prolonging of the free evolution time. The feasibility of such a periodical feedback is verified by the theory and experiment, respectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 702001 (2017)
Validation and Optimization of Discomfort Glare Model for White LED
Feng Ayang, Li Le, Zhou Li, and Lin Yandan
In order to verify the applicability of the discomfort glare evaluation model of small size light source to LED, the discomfort glare is generated by white LED of two kinds of color temperature. The experiment is conducted under four kinds of glare luminance and viewing angles. Observers are asked to give a deBoer ratiIn order to verify the applicability of the discomfort glare evaluation model of small size light source to LED, the discomfort glare is generated by white LED of two kinds of color temperature. The experiment is conducted under four kinds of glare luminance and viewing angles. Observers are asked to give a deBoer rating score under each condition. The results show that lager eccentric angle of white LED leads to lager contrast ratio. Lager glare luminance and smaller eccentric angle lead to higher deBore rating score, namely more discomfort glare. The small size light source model UGRsmall and the position coefficient modified models UGRS1 and UGRS2 are verified experimentally. The results show the high correlation between the calculated value of the model and the subjective experiment of discomfort glare rating. Further, model UGRSa is obtained by adding optimal coefficients of UGRS2 and optimizing them. Model UGRSk is obtained by adding eccentric angle into model UGRsmall and correcting it. UGRSa and UGRSk both have better performance..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 733001 (2017)
Atmospheric Optics and Oceanic Optics
Retrieval of Aerosol Optical Parameters Based on Ring Effect Observed by MAX-DOAS
Mou Fusheng, Li Ang, Wu Fengcheng, Xie Pinhua, Wang Yang, Chen Hao, Xu Jin, and Li Suwen
Ring effect is defined as the phenomenon that the depth of solar Fraunhofer lines shallows caused by solar rotational Raman scattering of sunlight. Aerosol can change the atmospheric light paths of photons and atmospheric scattering properties, and then influence the filling-in of Fraunhofer lines, so we can retrieve tRing effect is defined as the phenomenon that the depth of solar Fraunhofer lines shallows caused by solar rotational Raman scattering of sunlight. Aerosol can change the atmospheric light paths of photons and atmospheric scattering properties, and then influence the filling-in of Fraunhofer lines, so we can retrieve the aerosol information from the intensity of Ring effect. Sensitivity of the Ring effect to optical parameters of aerosol is analyzed, including aerosol optical depth, single scattering albedo and asymmetry factor. A new method for determining aerosol optical properties by ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) observation and the atmospheric radiative transfer model is developed. The MAX-DOAS retrieval result is in good agreement with the measurement result from sun photometer. The study shows that the Ring effect observed by ground-based MAX-DOAS can be used to detect the aerosol properties..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 701001 (2017)
Calculation of Whole Atmospheric Aerosol Optical Depth Based on Micro-Pulse Lidar
Chen Shasha, Xu Qingshan, Xu Chidong, Yu Dongsheng, and Chen Xiaowei
An algorithm is proposed to calculate the whole atmospheric aerosol optical depth (AOD) with aerosol scale height based on micro-pulse lidar data. Vertical extinction coefficient profiles and surface horizontal extinction coefficient of aerosol can be retrieved with the data vertically and horizontally measured by lidaAn algorithm is proposed to calculate the whole atmospheric aerosol optical depth (AOD) with aerosol scale height based on micro-pulse lidar data. Vertical extinction coefficient profiles and surface horizontal extinction coefficient of aerosol can be retrieved with the data vertically and horizontally measured by lidar. The vertical extinction coefficient profiles of aerosol are classified into four types, and different fitting methods are utilized to obtain aerosol scale height. Aerosol scale height is combined with surface extinction coefficient to calculate the whole atmospheric AOD. Comparison is made between the calculated results and those measured by sun-photometer in the same area simultaneously, and we find that the compared results show a good agreement. The average relative error is less than 6.7%. The proposed method provides a new technological means to calculate atmospheric AOD during the partly cloudy conditions and the night..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 701002 (2017)
Propagation Quality of Laser Diode Beam in Anisotropic Non-Kolmogorov Atmospheric Turbulence
Li Yan, Qi Jun, and Chen Feinan
The distribution of laser diode beam is described in the form of mixed Hermite-Gaussian mode. We study the relationship between beam waist width and beam propagation factor by using the beam second-order term matrix. The influences of generalized exponent and anisotropy coefficient on beam propagation factor are analyzThe distribution of laser diode beam is described in the form of mixed Hermite-Gaussian mode. We study the relationship between beam waist width and beam propagation factor by using the beam second-order term matrix. The influences of generalized exponent and anisotropy coefficient on beam propagation factor are analyzed. Results show that，for different turbulence intensity, there are different beam widths which make the beam propagation factor minimum. In addition, the increasing of anisotropy coefficient of atmospheric turbulence model reduces the influence of atmospheric turbulence on beam propagation factor. Simulation for the two-dimensional beam quality trace illustrates that the influence of anisotropy coefficient on beam propagation factor trace will be more obvious when the propagation distance is increasing. The result may help the development of atmospheric laser beam propagation theory and has important significance in applications of atmospheric optical communication and lidar detection..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 701003 (2017)
Diffraction and Gratings
Generation of Femtosecond Pulse Train by Stratified Volume Holographic Grating
Yan Xiaona, Zhao Jiayuan, Chen Yuanyuan, Wang Yan, and Dai Ye
Based on the Kogelnik′s coupled-wave theory and transfer matrix method, the expressions of temporal and spectral diffracted field and intensity are deduced, while a femtosecond pulse incidents on a transmitted stratified volume holographic grating (SVHG). Simulation results show that, each VHG layer diffracts out a subBased on the Kogelnik′s coupled-wave theory and transfer matrix method, the expressions of temporal and spectral diffracted field and intensity are deduced, while a femtosecond pulse incidents on a transmitted stratified volume holographic grating (SVHG). Simulation results show that, each VHG layer diffracts out a sub-pulse and the waveform of which is modulated by corresponding VHG layer and and buffer layers parameters. The buffer layers placed on VHG′s right side will translate the diffracted sub-pulses along the negative time-axis, whereas the left side will not translate peak position, such property can be used to realize modulated femtosecond pulse train by controlling VHG and buffer layers parameters. At last, an explanation on these phenomena is given based on the diffraction efficiency and expressions of diffracted spectrum.Key words.
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 705001 (2017)
Fiber Optics and Optical Communications
Optimization of Light Source Layout in Indoor Visible Light Communication Based on White Light-Emitting Diode
Zhao Li, and Peng Kai
The illumination based traditional source layout has the problem of uneven illumination, which results in blind effect of communication and greatly affects the reliability of communication system. In order to solve these problems, a 4 m×4 m×3 m room is taken as the model, and the illumination compensation tecThe illumination based traditional source layout has the problem of uneven illumination, which results in blind effect of communication and greatly affects the reliability of communication system. In order to solve these problems, a 4 m×4 m×3 m room is taken as the model, and the illumination compensation technology is used in the common indoor light source layout to optimize the layout. A kind of light source layout which is composed of five light-emitting diode arrays is obtained. With this kind of layout, the power consumption of the system can be reduced, and at the same time the uniformity of illumination can be improved. In order to balance the reliability of visible light communication (VLC) system, the indoor illumination standard deviation and the average bit error rate (BER) on receiving plane in communication system are used to build a system optimization model function f(L,i). When f(L,i) reaches the minimum value, it can meet the requirements of the receiving plane illumination and the BER. The simulation results show that the f(L,i) can reach the minimum value when L=0.35 m and i=0.025 m. For the receiving plane, the minimum illumination value is 301.26 lx, the maximum illumination value is 389.90 lx, and the illumination uniformity is 93.24%. At the same time, the illumination standard deviation is 20.1, the power consumption is 140.5 W, and the BER is 6.39×10-7. The proposed system takes the uniformity of indoor illumination distribution on receiving plane and the communication reliability into account, which provides an optimization method for the light source layout of indoor VLC..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 706001 (2017)
Performance of Adaptive Modulation Coding System for Atmospheric Laser Communication Under Discrete Rate Condition
Wang Lei, Hao Shiqi, Zhang Dai, and Wang Yong
For the decrease of system spectral efficiency caused by atmospheric turbulence, an adaptive modulation and coding system for atmospheric laser communication under discrete rate condition is studied. A turbulent channel model is established from the viewpoint of signal layer, and the probability density function of insFor the decrease of system spectral efficiency caused by atmospheric turbulence, an adaptive modulation and coding system for atmospheric laser communication under discrete rate condition is studied. A turbulent channel model is established from the viewpoint of signal layer, and the probability density function of instantaneous signal to noise ratio in turbulent channel is presented and verified by outfield experiments. The system spectral efficiency and bit error rate formulas are derived theoretically. Simulation results indicate that the adaptive modulation and coding system for atmospheric laser communication is superior to the traditional single transmission mode system. In addition, the characteristics of spectral efficiency curves and error rate curves are studied. Influences of bit error rate requirement and turbulence intensity on system performance are analyzed. Results show that the spectral efficiency is greatly improved when we decrease the bit error rate requirement. The lower the bit error rate requirement is, the weaker the turbulence intensity is, and the higher the spectral efficiency is..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 706002 (2017)
Algorithm of Coherent Optical Orthogonal Frequency Division Multiplexing-Passive Optical Network System Based on Optical-Comb Wave
Chen Rongrong, Kuang Caixia, Ma Junjie, Wang Min, Lin Rujian, and Zhang Qianwu
A structure and a digital signal processing algorithm of orthogonal frequency division multiplexing-passive optical network (OFDM-PON) downstream coherent detection system based on optical-comb wave are studied. A multi-wavelength optical-comb wave generator is used as the source of optical line terminal. One of the waA structure and a digital signal processing algorithm of orthogonal frequency division multiplexing-passive optical network (OFDM-PON) downstream coherent detection system based on optical-comb wave are studied. A multi-wavelength optical-comb wave generator is used as the source of optical line terminal. One of the wavelengths is used as OFDM signal carrier and its adjacent wavelength is used as local oscillation light. In this way, the optical phase noise cancellation is achieved in coherent reception at optical network unit. Since the carrier offset and optical phase noise are avoided, the digital signal processing can be simplified. The comparison of the performance of three phase estimation algorithms, which are pilot aided (PA) algorithm, maximum likelihood (ML) algorithm and PA+ML algorithm, are carried out. It is found that the performance of the PA+ML algorithm is far more better. It can reduce the number of pilot subcarriers to 2 and the receiver sensitivity can be improved to -30 dBm. The hardware and software designs of the OFDM-PON system are expected to be a promise solution for the next generation optical access networks..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 706003 (2017)
Ultra-Stable Optical Frequency Signal Transfer in 210 km Urban Communication Link
Zang Qi, Deng Xue, Cao Qun, Gao Jing, Jiao Dongdong, Liu Jie, Xu Guanjun, Dong Ruifang, Liu Tao, and Zhang Shougang
We establish a 210 km optical frequency signal transfer test link along the telecom provincial backbone optical fiber network between Xi’an and Xian Yang, and the loss of the link is 0.23 dB/km. A fiber interferometer based laser with linewidth of 200 Hz is used as the light source, and the laser is conveyable. Two bilWe establish a 210 km optical frequency signal transfer test link along the telecom provincial backbone optical fiber network between Xi’an and Xian Yang, and the loss of the link is 0.23 dB/km. A fiber interferometer based laser with linewidth of 200 Hz is used as the light source, and the laser is conveyable. Two bilateral erbium-doped optical fiber amplifiers (EDFAs) with low noise are used to compensate the fiber link loss and increase the transmission distance of signal. The average gain of amplifier is controlled at about 15 dB to avoid the self-excited oscillation. The additional phase noise of the fiber link under different conditions is measured and analyzed, and the regular disturbance caused by the railway vibration is observed. The phase noise in the link is suppressed by 23 dB when we use the noise suppression system. When the noise data from the railway vibration is eliminated, the second level frequency stability of the 210 km urban communication link can achieve 1.51×10-14 and be better than 5×10-17 at 104 s. The remote transfer test for optical frequency signal based on 210 km communication link is completed, and the main influence factors limiting the frequency stability are analyzed. The supplementary requirements are put forward for the current fiber setting way. The study provides theoretical supplement for achieving high accuracy optical frequency signal transmission and comparison based on the communication link..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 706004 (2017)
Holography
Frequency Domain Compressive Reconstruction of Fresnel Hologram for Complex Three-Dimensional Object
Wang Xiangxiang, Zhang Cheng, Shen Chuan, Zhang Kai, Wang Ye, and Wei Sui
Aiming at the problem of similarity and redundancy of information of three-dimensional (3D) object hologram generated by computer, a method which based on 3D total variation sparse model to realize frequency domain of Fresnel hologram′s reconstruction of complex 3D object is proposed in this paper. Firstly, the FresnelAiming at the problem of similarity and redundancy of information of three-dimensional (3D) object hologram generated by computer, a method which based on 3D total variation sparse model to realize frequency domain of Fresnel hologram′s reconstruction of complex 3D object is proposed in this paper. Firstly, the Fresnel hologram of 3D object is obtained by using computation; then, the frequency domain of Fresnel hologram is sub-sampled by using the incoherent variable density sub-sampling pattern of frequency domain with probability density function obeying exponential distribution; finally, the sub-sampling frequency domain of hologram can be reconstructed by using compressive sensing reconstruction algorithm. Simulation experiments verify the feasibility of the method, compared with the traditional method of using Gauss random measurement matrix to subsample the spatial domain of hologram, the method proposed in this paper can improve the peak signal to noise ratio of the reconstructed image, especially in the condition of low-sampling rate..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 709001 (2017)
Image Processing
A Sequence Images Super-Resolution Enhancement Approach Based on Frequency-Domain
Tan Zheng, Xiangli Bin, Lü Qunbo, Sun Jianying, Zhao Na, Fang Yu, and Liu Yangyang
Aiming at solving the problem of imaging system degradation caused by the shortage of sensor Nyquist frequency and the point spread effect of optical system, we propose a modified super-resolution enhancement method for multiple input images in the frequency domain framework. In image registration, we build the phase dAiming at solving the problem of imaging system degradation caused by the shortage of sensor Nyquist frequency and the point spread effect of optical system, we propose a modified super-resolution enhancement method for multiple input images in the frequency domain framework. In image registration, we build the phase difference model by considering the impact of spectrum aliasing and interpolation transformations, so the sub-pixel information obtained from the model is more accurate. Based on the simultaneous autoregressive prior, the joint Gaussian distribution model combined with the Bayes approach is built to restore the interpolation results. The experimental results demonstrate that the proposed algorithm is effective with low computational complexity..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 710001 (2017)
An Uniform Simplification Algorithm for Scattered Point Cloud
Li Renzhong, Yang Man, Liu Yangyang, and Zhang Huanhuan
Aiming at the problems of high density, long reconstruction time and low reconstruction efficiency for scattered point cloud data, a new uniform simplification algorithm for scattered point cloud data is proposed. This algorithm is based on the open-source C++ programming library point cloud library (PCL). Firstly, a KAiming at the problems of high density, long reconstruction time and low reconstruction efficiency for scattered point cloud data, a new uniform simplification algorithm for scattered point cloud data is proposed. This algorithm is based on the open-source C++ programming library point cloud library (PCL). Firstly, a K-nearest neighborhood voxel grid is built by voxel grid class in PCL. Next, according to the bounding box algorithm the K-nearest neighborhood distance of the point cloud data is calculated and the normal of the point cloud data is estimated. Then the barycenter of each small voxel grid is established, which replaces all point cloud data in the voxel grid to achieve point cloud simplification. Finally, the simplified point cloud data is reconstructed and displayed with triangular mesh by greedy projection triangulation class. The experimental results show that in the premise of fully retaining geometric characteristics of point cloud data, the proposed algorithm can effectively remove partial redundancy of the point cloud data and simplify the data uniformly without large-scale blank area, and the reconstruction efficiency is improved..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 710002 (2017)
A Fusion Algorithm of Infrared and Visible Image Based on NSSCT
Wu Dongpeng, Bi Duyan, He Linyuan, Ma Shiping, and Fan Zunlin
To overcome the weakness that traditional fused image cannot express the image contrast and details well, an image fusion algorithm is proposed based on non-subsampled shearlet-contrast transform (NSSCT). The correlation and diversity between different high coefficients are analyzed by non-subsampled shearlet transformTo overcome the weakness that traditional fused image cannot express the image contrast and details well, an image fusion algorithm is proposed based on non-subsampled shearlet-contrast transform (NSSCT). The correlation and diversity between different high coefficients are analyzed by non-subsampled shearlet transform (NSST), and the NSSCT is built with same orientation high coefficients, which reserves contrast and details image information. Based on image characters of lower frequency, low coefficients are fused by enhancing the salient targets of image. Fused image with higher contract and enhanced details is obtained by inverse NSSCT. Compared with several popular algorithms, such as wavelet transform, NSST and saliency map, the experimental results show that the proposed algorithm is obviously of superiority in reserving image contrast and details..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 710003 (2017)
Imaging Systems
Polarization-Difference Imaging System with Adjustable Optical Path and Its Characteristics
Wang Tian, Niu Mingsheng, Bu Miaomiao, Han Peigao, Hao Dianzhong, Ma Lili, and Song Lianke
The polarization-difference interference imaging spectrum system with adjustable optical path based on the combination of the angular shear of Wollaston prism and the lateral shear of Savart polariscope, can not only simultaneously obtain the two-dimensional space image and the interference image in the orthogonal polaThe polarization-difference interference imaging spectrum system with adjustable optical path based on the combination of the angular shear of Wollaston prism and the lateral shear of Savart polariscope, can not only simultaneously obtain the two-dimensional space image and the interference image in the orthogonal polarization direction of the target, but also obtain the interference image in the orthogonal polarization direction under different optical path differences by adjusting the thickness of Savart polariscope. The features of the system are simultaneous acquisition of orthogonal images and real-time adjustment of optical path. The structure and theoretical principle of the polarization-difference interference imaging spectrum system with adjustable optical path are demonstrated. Expressions for the interference intensity are derived as well. The variation ranges of the optical path difference and the lateral displacement for the modulated Savart polariscope (MSP) and the modulated wide-field-of-view Savart polariscope (MWSP) are analyzed in detail. Through the contrast it is concluded that the optical path difference is little while the lateral displacement of MWSP is 50% higher than that of MSP. The results provide important evidence for the type selection of the Savart polariscope..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 711001 (2017)
Design of Pendulum Staring Search Imaging Along the Track with High Resolution CMOS Camera
Yang Xiubin, Jiang Li, Wang Shaoju, Wang Min, Fan Guowei, and Wang Yamin
In order to realize the staring search imaging with a certain overlap of long strip area in the vertical direction of high resolution array camera, a pendulum staring search imaging model is designed with the staring gesture and earth movement complement. Based on the division of the strip layer by layer and the constrIn order to realize the staring search imaging with a certain overlap of long strip area in the vertical direction of high resolution array camera, a pendulum staring search imaging model is designed with the staring gesture and earth movement complement. Based on the division of the strip layer by layer and the construction of three-dimentional movement rate, the guiding strategy of real-time posture change and earth rotation compensation is designed. Besides, the pendulum adaptive search imaging parameters and real-time variation point orientation are calculated, and the effect of attitude control precision on imaging is analyzed. Finally, a ground scaling simulation experiment is carried out through the CMOS prototype, the attitude control three-axis flotation simulation platform and curved LED target system. The result shows that a gradually variational strip area with the inter frame overlap ratio more than 85% can be obtained using the pendulum staring search imaging when the pendulum staring adaptive search imaging parameter is 0.95, which is enlarged by four times than the staring imaging area. When the attitude control precision is better than 0.05° and attitude stability is better than 0.003 (°) s-1, the image motion mismatching quantity is less than 0.9 pixel and the corresponding modulation transfer function can reach up to 0.1559..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 711002 (2017)
A Focus Detection Method for Ground-Based Solar Telescope
Fang Yuliang, Liu Guangqian, Jin Zhenyu, Li Pengfei, and Liu Zhong
Intense solar radiation leads to thermal deformation of the solar telescope opto-mechanical system, triggering obvious time-varying focus shifts. Defocus aberration has an adverse effect on high-resolution observation and reduces the image spatial resolution. Therefore, the defocus aberration is necessary to be detecteIntense solar radiation leads to thermal deformation of the solar telescope opto-mechanical system, triggering obvious time-varying focus shifts. Defocus aberration has an adverse effect on high-resolution observation and reduces the image spatial resolution. Therefore, the defocus aberration is necessary to be detected and compensated. Considering the effects of atmospheric turbulence, the focus detection method based on general image processing can not be applied well on ground-based solar telescopes. The focus detecting method based on Shack-Hartman wavefront detection which commonly used in astronomical telescopes is invalid at observing the solar limb and the low contrast solar granulation. The focus detecting method based on image power spectrum analysis is provided. This method used the average value of the low-frequency components of the image spectrum ratio as the cost function for focus detection, which can effectively eliminate the impact of object structure and atmospheric turbulence. Experimental results show that the detecting accuracy and frequency of this method can meet the requirement of high-resolution observations for different objects on ground-based solar telescope..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 711003 (2017)
Bioluminescence Tomography Based on Iterative Support Detection
Yu Jingjing, Tian Jing, Wang Haiyu, and Li Qiyue
Bioluminescence tomography (BLT) is an optical molecular imaging technique with high sensitivity and specificity, and it can provide three-dimensional distribution of the internal source according to the detected boundary light intensity. However, the source reconstruction with limited measurements is a challenging proBioluminescence tomography (BLT) is an optical molecular imaging technique with high sensitivity and specificity, and it can provide three-dimensional distribution of the internal source according to the detected boundary light intensity. However, the source reconstruction with limited measurements is a challenging problem. We take advantage of the sparsity feature of bioluminescence source and formulate the BLT source reconstruction into an L1 norm minimization problem. The iterative detection support (ISD) algorithm is used to realize more accurate and faster reconstruction with limited data. The reconstruction algorithm alternatively runs two operations, i.e., support detection and signal reconstruction, until the solution meets the accuracy requirement. Simulations based on a digital mouse are designed to assess the location ability of the ISD method, and the result is compared with those of other three representative sparse algorithms. The simulation results show that the ISD method can achieve accurate reconstruction in both single-source and double-source cases..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 711004 (2017)
Instrumentation, Measurement and Metrology
Internal Stray Radiation Measurement for Cooled Infrared Imaging Systems Using Ambient Temperature
Tian Qijie, Chang Songtao, He Fengyun, and Qiao Yanfeng
The suppression level of internal stray radiation is a key indicator to evaluate infrared imaging systems. Being related to ambient temperature, the internal stray radiation must be measured at multiple ambient temperatures, and the measurement has such disadvantages as high cost, long duration and high demand for expeThe suppression level of internal stray radiation is a key indicator to evaluate infrared imaging systems. Being related to ambient temperature, the internal stray radiation must be measured at multiple ambient temperatures, and the measurement has such disadvantages as high cost, long duration and high demand for experimental setups. To solve these problems, the effect of ambient temperature on internal stray radiation is studied by building a multi-integral time calibration model, and a method is proposed to measure internal stray radiation of cooled infrared imaging systems using ambient temperature. In this method, the influence of internal factors of the detector on the system output is obtained by calibrating the cooled infrared detector. Combining the calibration results of the infrared imaging system under a certain ambient temperature, the quantitative relation between internal stray radiation and ambient temperature is resolved. Then the internal stray radiation can be calculated at arbitrary integration times and ambient temperatures. The effectiveness of the proposed method is verified by radiometric calibration experiments. Experimental results indicate that, with the proposed method, high-precision measurement of internal stray radiation in cooled infrared imaging systems can be achieved..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 712002 (2017)
Real-Time Loss Measurement of Reflecting Mirrors Applied in Plasma Environment
Zhai Liang, Wang Tao, Bai Manshe, Zuo Yijuan, Su Yu, Liu Xin, Chen Jing, and Zhu Liangjian
A new system for the real-time loss increment measurement of reflecting mirrors is designed and built, and the loss change curve of reflecting mirrors is gained. The results show that the system is capable of effectively monitoring the loss change process of reflecting mirrors in the plasma environment and can reveal tA new system for the real-time loss increment measurement of reflecting mirrors is designed and built, and the loss change curve of reflecting mirrors is gained. The results show that the system is capable of effectively monitoring the loss change process of reflecting mirrors in the plasma environment and can reveal the change law. The actual loss increment is closely related to the natural standing time after the interaction of reflectors with plasma. The curve amplitude of loss change is quite different when the discharging current and the cavity pressure change. These measurement results can provide an experimental evidence for the study of the loss change mechanism of reflectors under the action of plasma..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 712001 (2017)
Lasers and Laser Optics
Performance of Laser Beam Combination System Based on Brightness
Jiang Man, Ma Pengfei, Zhou Pu, and Liu Zejin
Beam combination is an important method to break through single laser power limit and obtain high power laser output. Brightness is taken as the criterion, and theoretical investigation about the combination effect of different methods is carried out. The pre-evaluation method of laser beam combination effect is given.Beam combination is an important method to break through single laser power limit and obtain high power laser output. Brightness is taken as the criterion, and theoretical investigation about the combination effect of different methods is carried out. The pre-evaluation method of laser beam combination effect is given. Relationship among three important parameters used to describe beam quality, including brightness, beam quality factor and Strehl ratio, are analyzed. The formula describing the relationship between brightness and Strehl ratio is given, and brightness scaling magnification formulas of coherent beam combination system and spectral beam combination system are obtained. The power and the brightness scaling amplification capability of the two systems are compared..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 714001 (2017)
Gain Competition Between Orthogonally Polarized Modes in Solid-State Lasers
Cheng Lijun, Yang Suhui, Zhao Changming, and Zhang Haiyang
According to Lamb′s semiclassical laser theory, whether the two modes in a solid-state laser can oscillate simultaneously depends on the mode-coupling coefficient between them. The coupling coefficient is defined as the ratio of cross-saturation factors and self-saturation factors. A dual-frequency Nd∶YAG solid-state lAccording to Lamb′s semiclassical laser theory, whether the two modes in a solid-state laser can oscillate simultaneously depends on the mode-coupling coefficient between them. The coupling coefficient is defined as the ratio of cross-saturation factors and self-saturation factors. A dual-frequency Nd∶YAG solid-state laser is built with two quarter-wave plates, and the frequency difference from 30 MHz to 1.3 GHz is obtained. On this basis, the noise power spectrum density of two orthogonally polarized modes is measured under different frequency differences, by which the coupling coefficients of gain competition between two modes are calculated. In theory, based on the Lamb′s semiclassical laser theory, the coupling coefficient expression is deduced, and the trend that the coupling coefficient decreases with the increasing of frequency difference is verified. The factors influencing the coupling coefficient are analyzed. It provides the theoretical foundation for further optimization of dual-frequency solid-state laser..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 714002 (2017)
Wavefront Error Modeling and Control Method for Large Aperture Optical Unit in High Power Solid-State Laser
Yao Chao, Wang Hui, Zhang Zheng, and Liu Tianye
The fine modeling analysis of wavefront error is carried out based on assembly structure and profile accuracy characteristic of typical large aperture laser transmission mirror in high power solid-state laser driver of inertial confinement fusion system. Wavefront error models of roughness，ripple and profile are studieThe fine modeling analysis of wavefront error is carried out based on assembly structure and profile accuracy characteristic of typical large aperture laser transmission mirror in high power solid-state laser driver of inertial confinement fusion system. Wavefront error models of roughness，ripple and profile are studied. To control the wavefront error caused by mounting force in assembly process within a reasonable range, a method combined root-mean-square(RMS) gradient and peak-to-valley (PV) value is proposed. Experiments are carried out to verify the feasibility of the proposed method. The study provides scientific instruction for wavefront error control in assembly process of large aperture mirror in SG-III host device..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 714003 (2017)
Machine Vision
Visual Background Extraction Algorithm Based on Superpixel Information Feedback
Chen Haiyong, Qie Lizhong, Yang Dedong, Liu Kun, and Li Lianbing
To solve the problems about the ghost, high frequency noises from dynamic background and background model update error, an improved visual background extraction algorithm is proposed. The original image is accurately segmented into several regions by employing the superpixel model. The superpixels of true moving objectTo solve the problems about the ghost, high frequency noises from dynamic background and background model update error, an improved visual background extraction algorithm is proposed. The original image is accurately segmented into several regions by employing the superpixel model. The superpixels of true moving object from visual background extraction results are reclassified. And the ghost region is accurately identified, which can immediately detect and feedback ghost information to refresh its background model. Thus, the key problem about ghost region detection in global scale is resolved. According to the superpixel segmentation results, the small noise objects are discarded and the holes filling strategies are added to enhance robustness of the proposed algorithm. Experimental results show that the precision and recognition rate are remarkably improved by employing standard datasets..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 715001 (2017)
Medical Optics and Biotechnology
Fluorescence Molecular Tomography Using a Stochastic Variant of Alternating Direction Method of Multipliers
Hou Yuqing, Jin Mingyang, He Xiaowei, and Zhang Xu
Increasing measurement information can effectively reduce the ill-posedness of the fluorescence molecular tomography(FMT) reconstruction. With the increase of data, the time of FMT reconstruction will increase significantly. In order to reduce the ill-posedness of FMT reconstruction and enhance reconstruction efficiencIncreasing measurement information can effectively reduce the ill-posedness of the fluorescence molecular tomography(FMT) reconstruction. With the increase of data, the time of FMT reconstruction will increase significantly. In order to reduce the ill-posedness of FMT reconstruction and enhance reconstruction efficiency under big data sets, a reconstruction method of improved stochastic variant of alternating direction method of multipliers (ADMM) is proposed by combining dual coordinate ascent (DCA) method and ADMM method. The proposed method offers a stochastic update rule base on the original ADMM method where each iteration requires only one or few sample observations, thus gives speed up of convergence, so that the objective function can get the optimal solution rapidly and achieve the effect of rapid reconstruction. Simulation experiments of digital mouse and real mouse experiment show that the proposed method can guarantee FWT reconstruction images′s accuracy and improve reconstruction efficiency..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 717001 (2017)
Nonlinear Optics
Theoretical Research on Optimization of Signal-Noise Ratio Based on Cascaded Four-Wave Mixing System
Wang Li, and Jing Jietai
Theoretical research on the optimization of the signal-noise ratio (SNR) based on the cascaded four-wave mixing process is performed. This cascaded four-wave mixing process includes the phase-sensitive and phase-insensitive two cascaded methods. In the phase-insensitive cascaded system, the intensity of the probe beam Theoretical research on the optimization of the signal-noise ratio (SNR) based on the cascaded four-wave mixing process is performed. This cascaded four-wave mixing process includes the phase-sensitive and phase-insensitive two cascaded methods. In the phase-insensitive cascaded system, the intensity of the probe beam is always amplified and the SNR of the probe beam is always reduced. However, in the phase-sensitive cascaded system, the intensity of the probe beam can be either amplified or reduced which depends on the total phase modulation of the light field in two Rb pools. Under the same intensity gain condition, the efficient gain in the phase-sensitive cascaded four-wave mixing system is greater than that in the phase-insensitive cascaded four-wave mixing system. In addition, when the total phase of the light field in two Rb pools is equal to 0 or 2π, both the intensity of the probe beam shows an amplification with the maximal amplitude, and the SNR is increased to the maximal value in the phase-sensitive cascaded four-wave mixing system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 719001 (2017)
Enhancement of Fifth-Order Nonlinearity Induced by Atomic Coherence
Liu Yutong, Niu Yueping, Lin Gongwei, and Gong Shangqing
The fifth-order Kerr nonlinear coefficient of Λ-type three-level system is measured using cavity transmission spectroscopy. The fifth-order nonlinear coefficients for two-level and Λ-type three-level systems are numerically simulated. Comparing the results of numerical simulation, it is found that atomic coherence has The fifth-order Kerr nonlinear coefficient of Λ-type three-level system is measured using cavity transmission spectroscopy. The fifth-order nonlinear coefficients for two-level and Λ-type three-level systems are numerically simulated. Comparing the results of numerical simulation, it is found that atomic coherence has an enhanced effect on nonlinear coefficients. Meanwhile, the simulation results of the third- and fifth-order polarizabilities are compared with the measured results, and it is found that the two results have good consistency..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 719002 (2017)
Optical Design and Fabrication
Calibration of Artificial Compound Eye System Based on Virtual Double Spherical Surfaces
He Jianzheng, Jian Huijie, Ma Mengchao, and Wang Keyi
In order to achieve detection and positioning of spatial objects, calibration of the designed artificial compound eye system is studied. The structure of the compound eye device is introduced. A calibration platform is designed and built based on the imaging characteristics of the compound eye, which can construct the In order to achieve detection and positioning of spatial objects, calibration of the designed artificial compound eye system is studied. The structure of the compound eye device is introduced. A calibration platform is designed and built based on the imaging characteristics of the compound eye, which can construct the full-field-of-view calibration target. A calibration method based on virtual targets of two spherical surfaces is proposed. A mathematical model is established to unify various sub-eye coordinate systems in the process of compound eye calibration and positioning. The specific steps of simultaneous multi-channel calibration or localization are described, in detail including the reasonable adjustment of system, the uniformity optimization of target distribution and the selection of the nonlinear mapping method and so on. Automatic operation of the calibration process can be achieved by computer control. Then, the nonlinear mapping relationship between the coordinates of the image spots and the target angle is established at two spherical surface positions. Finally, a verification experiment is carried out for the proposed calibration method. The experimental results show that the relative error of the target positioning is lower than 0.5% in the field of view of 60° after calibration of the compound eye system, and the root mean square error of the positioning angle is 1.96 mrad. The proposed method can satisfy the calibration requirements of the designed compound eye, and the calibrated compound eye can achieve measurement of the space object well..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 722001 (2017)
Effect of Dust Accumulation on Focal Energy Flux Density Distribution of Trough Solar Concentrator and Concentration Optimization
Yan Suying, Chang Zheng, Wang Feng, and Tian Rui
In order to study the effect of dust on the optical efficiency of solar concentrator and the distribution of energy flow in metal tube, the influence of dust on the optical efficiency of the condenser is analyzed theoretically and the dusting conditions of the trough solar concentrator are simulated. Moreover, by analyIn order to study the effect of dust on the optical efficiency of solar concentrator and the distribution of energy flow in metal tube, the influence of dust on the optical efficiency of the condenser is analyzed theoretically and the dusting conditions of the trough solar concentrator are simulated. Moreover, by analyzing the heat transfer of the parabolic trough collector system using the Monte Carlo ray tracing method and the finite element volume method, the energy flux density and circumferential temperature distribution (CTD) are generated. The results show that the accumulated dust has significant effect on the direction of reflected light and the energy flux density of the metal tube wall surface, and the distribution of the flow density of the wall by the dust has certain influence on CTD. According to the influence of CTD on the parabolic trough collector system, a new method is put forward that a secondary homogeneous reflector is added based on traditional parabolic trough collector system. The addition of the secondary reflector makes the energy flux distribution of the metal tube tend to be uniform and CTD of the metal tube of the new parabolic trough collector system reduce significantly, thus reducing the dust accumulated effect on the spot solar collector system. This method provides some reference for the optimization of parabolic trough solar concentrating systems..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 722002 (2017)
Beam Alignment Error and Its Control in Scanning Beam Interference Lithography System
Wang Wei, Bayanheshig, Pan Mingzhong, Song Ying, and Li Wenhao
In order to improve alignment accuracy of exposure beams in the scanning beam interference lithography system and guarantee quality of the fabricated grating mask groove shape, an alignment error model of exposure beams is established and used to analyze the beam alignment error. Meanwhile, to meet the requirement of tIn order to improve alignment accuracy of exposure beams in the scanning beam interference lithography system and guarantee quality of the fabricated grating mask groove shape, an alignment error model of exposure beams is established and used to analyze the beam alignment error. Meanwhile, to meet the requirement of the system for beam overlapping accuracy, an automatic beam alignment system is designed and fabricated, and alignment experiments are conducted on the exposure beams. Analysis results show that the exposure contrast on the grating substrate surface decreases obviously when the beams have large alignment errors. Under the exposure mode of stepping-scanning, uneven exposure appears at different positions of the photoresist surface, which influencing the quality of grating mask groove shape. The designed alignment system can adjust the beam angles and positions. The system shows good convergence performance as a whole. After multi-step adjustment, the position alignment accuracy of the beams exceeds 10 μm, and the angle alignment accuracy of the beams exceeds 9 μrad. The alignment accuracy of exposure beams satisfies system requirements and the expected purpose is achieved..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 722003 (2017)
Optics at Surfaces
Design and Preparation of Planar Lens Based on V-Shaped Nanoantennas
Jiao Jiao, Luo Xiangang, and Zhao Qing
Conventional lens encounters challenges in the application of micro-nano optical system due to its big volume and poor performance. While metallic nanostructure can couple the free light wave to produce surface plasmon polaritons. And we can adjust and control the incident light wave by controlling the surface plasmon Conventional lens encounters challenges in the application of micro-nano optical system due to its big volume and poor performance. While metallic nanostructure can couple the free light wave to produce surface plasmon polaritons. And we can adjust and control the incident light wave by controlling the surface plasmon polaritons. V-shaped plasmonic nanoantenna stands out among the metallic nanostructures which are able to realize beam controlling because of its double resonant effect and comprehensive phase tuning range of 0-2π. Firstly, based on the V-shaped nanoantenna, a super lens which can realize high efficient focus at 34 μm is designed. Then by using focused electron beam and photolithography technique, the samples are prepared. Finally, the characterization analysis and optical detection of the samples are carried out. These works have the potential to promote the applications of V-shaped nanoantenna in laser direct writing and optical integration..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 724001 (2017)
Surface-Plasmon Resonance-Enhanced Upconversion Luminescence of Single Nanocrystal Based on Single Gold Nanorod
Xue Yingxian, Rong Youying, Ma Qiang, Pan Chengda, Chen Lingxiao, Wu E, and Wu Botao
Rare-earth ion doped upconversion nanocrystals show wide applications in bioimaging and photovoltaics. However, its low upconversion efficiency limits their applications. The single Au nanorod and single upconversion nanocrystal are coupled in nanometer scale with an atomic force microscope probe manipulation. The effeRare-earth ion doped upconversion nanocrystals show wide applications in bioimaging and photovoltaics. However, its low upconversion efficiency limits their applications. The single Au nanorod and single upconversion nanocrystal are coupled in nanometer scale with an atomic force microscope probe manipulation. The effect of localized surface plasmon resonance of Au nanorod on the nanocrystal′s upconversion luminescence is studied by single-particle spectroscopy. Results show that the upconversion luminescence intensity of nanocrystal shows strong dependence on the laser polarization direction. When the laser polarization is parallel to the long axis of Au nanorod, the maximum enhancement folds of 18 and 40 are obtained for the green and red upconversion luminescence of nanocrystal..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 724002 (2017)
Optics in Computing
Calculation of Optical Cross Section Areas of Spatial Objects Based on OpenGL Picking Technique
Xu Can, Zhang Yasheng, Li Peng, and Li Jilian
The accurate optical cross section areas (OCSA) calculation of spatial objects is an important foundation and prerequisite for the analysis and recognition of spatial object characteristics. Aiming at the problems of the poor real-time performance of the grid model used in the faceting method and the weak ability for tThe accurate optical cross section areas (OCSA) calculation of spatial objects is an important foundation and prerequisite for the analysis and recognition of spatial object characteristics. Aiming at the problems of the poor real-time performance of the grid model used in the faceting method and the weak ability for the description of bidirectional-reflectance-distribution-function (BRDF) of material by using the computer graphics method, an OCSA calculation method for complex space objects based on the OpenGL picking technique is proposed. The primary occlusion judgment of facets is realized by the OpenGL picking technique, and the second occlusion judgment between facets is realized based on the improved Z buffering technique. Therefore, the detailed information of facets is preserved without loss of real-time performance, which makes the application of precise BRDF model and the accurate calculation of OCSA possible. One nested cylinder and one satellite model are designed, and their OCSA value is calculated. The maximum OCSA error of the nested cylinder is less than 0.08% and the average time consumption on a general computer is less than 0.01 s. The average time consumption of OCSA for a satellite is less than 0.1 s. The results verify the correctness and real-time performance of the proposed method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 720001 (2017)
Physical Optics
Infrared Radiation Characteristics of High-Temperature H2O and CO2 Gas Mixture Jet Flows
Zheng Haijing, Bai Tingzhu, Wang Quanxi, and Cao Fengmei
Infrared radiation characteristics of the high-temperature H2O and CO2 gas mixture jet flows are investigated with the numerical simulation method. The infrared band is divided into five bands (1.32-1.69 μm, 1.56-2.27 μm, 2.27-3.8 μm, 3.8-8.3 μm and 8.3-20 μm) according to the absorption features of H2O and CO2 gases. Infrared radiation characteristics of the high-temperature H2O and CO2 gas mixture jet flows are investigated with the numerical simulation method. The infrared band is divided into five bands (1.32-1.69 μm, 1.56-2.27 μm, 2.27-3.8 μm, 3.8-8.3 μm and 8.3-20 μm) according to the absorption features of H2O and CO2 gases. The model for describing the infrared radiation characteristics of wake flows from an engine nozzle is set up, and the radiation characteristic distributions of jet flows in the five infrared bands are numerically simulated based on this model. The results show that the more H2O content in the jet flows, the more contributions to the energy diffusion, thereby the temperature of jet flows and the quantity of radiation are lower. In addition, there is the maximum radiation quantity in the mid-wave infrared band and the minimum radiation quantity in the long wave infrared band..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 726001 (2017)
Optimal Design for Broadband Polarization State Analyzer of Ferroelectric Liquid Crystal
Li Jianxin, Liu Qin, Zhou Jianqiang, Bai Caixun, Xu Yixuan, Yuan Heng, and Liu Jie
Polarization state analyzer (PSA) of ferroelectric liquid crystal is the core component for broadband polarization imaging. The ability of suppressing noise highly affects the polarization measurement results. Therefore, solving optimal design problem of broadband PSA of ferroelectric liquid crystal has a great signifiPolarization state analyzer (PSA) of ferroelectric liquid crystal is the core component for broadband polarization imaging. The ability of suppressing noise highly affects the polarization measurement results. Therefore, solving optimal design problem of broadband PSA of ferroelectric liquid crystal has a great significance. The Stokes measurement matrix of the PSA of ferroelectric liquid crystal is deduced in terms of the basic principle of broadband polarization imaging measurement. The azimuth parameters of polarization devices are optimized by genetic algorithm，evaluation criteria of condition number (CN) and equally weighted variance (EWV). The optimal device combination and optimal azimuth parameters of PSA of ferroelectric liquid crystal are obtained. Finally, a multi-band experimental device is set up according to the results of optimal design. The imaging experiments are carried out by measuring the 3D glasses and the polarizer. The experimental results show that the polarization measurement device, which is designed by the proposed method, can effectively measure the polarization characteristic of the targets..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 726002 (2017)
Active Control of Nonreciprocal Optical Transmission Direction
Ren Kun, Fan Jingyang, and Ren Xiaobin
In order to realize the active control of nonreciprocal optical transmission, a structure based on graphene photonic crystals and magneto-optical semiconductor materials is proposed. By adding external magnetic field on the magneto-optical semiconductor, the time-reversal symmetry is broken which contributes to the obtIn order to realize the active control of nonreciprocal optical transmission, a structure based on graphene photonic crystals and magneto-optical semiconductor materials is proposed. By adding external magnetic field on the magneto-optical semiconductor, the time-reversal symmetry is broken which contributes to the obtainment of nonreciprocal magnetic Tamm plasmon polaritons (MTPP). The influences of structural parameters, external magnetic field and graphene chemical potential on the MTPP are studied by analyzing the transmission spectra under different conditions. The results show that the active control of the unidirectional wave and the flexible switch between one-way forward and one-way backward transmission can be realized by modulating the external magnetic field and graphene chemical potentials. This structure and its modulation method have promising applications in optical diodes and optical switches..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 726003 (2017)
Quantum Optics
Entanglement Characteristics in Fiber-Coupled Two-Cavity Systems
Lu Daoming
By employing the negative eigenvalue to describe the entanglement between two systems, the entanglement characteristics between the two cavities and between the cavity and the atomic ensemble in the fiber-coupled cavity model are studied under the condition that both cavities trap atomic ensembles. The effects of the nBy employing the negative eigenvalue to describe the entanglement between two systems, the entanglement characteristics between the two cavities and between the cavity and the atomic ensemble in the fiber-coupled cavity model are studied under the condition that both cavities trap atomic ensembles. The effects of the number of atoms contained in the atomic ensemble and the fiber-cavity coupling coefficient on the entanglement characteristics are discussed. The results show that the Rabi oscillation frequency of the entanglement between the two cavities as well as that between the cavity and the atomic ensemble increases with the increase of the number of atoms. As the fiber-cavity coupling coefficient increases, the entanglement between the two cavities as well as that between the cavity and the atomic ensemble is strengthened..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 727001 (2017)
Remote Sensing and Sensors
On-Orbit Modulation Transfer Function Detection of High Resolution Optical Satellite Sensor Based on Reflected Point Sources
Xu Weiwei, Zhang Liming, Si Xiaolong, Li Xin, Yang Baoyun, and Shen Zhengguo
Modulation transfer function (MTF) can be used to evaluate the image quality of high resolution optical satellite sensors. On-orbit MTF detection is significant to the application of high resolution satellite remote sensing data and the development of future satellite sensors. A directly detection method based on refleModulation transfer function (MTF) can be used to evaluate the image quality of high resolution optical satellite sensors. On-orbit MTF detection is significant to the application of high resolution satellite remote sensing data and the development of future satellite sensors. A directly detection method based on reflected point source is presented, and the point spread function (PSF) and MTF value are obtained based on remote sensing image data. According to the imaging relationship and point source imaging data, the one-dimensional line spread function value of optical satellite sensor imaging system can be acquired by way of solving non-linear equations. Additionally, the Gaussian model which is usually used to characterize the PSF of high resolution optical satellite sensor is also verified. The results show that the difference of on-orbit MTF detection results of optical satellite sensor based on reflected point sources is less than 5% compared with that of the method based on knife-edge tarps. The proposed approach can achieve on-orbit MTF detection for high resolution optical satellite sensor..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 728001 (2017)
Spatial-Spectral Semi-Supervised Local Discriminant Analysis for Hyperspectral Image Classification
Hou Banghuan, Yao Minli, Wang Rong, Zhang Fenggan, and Dai Dingcheng
In traditional hyperspectral image classification algorithm based on feature extraction, spectral information is usually considered while spatial information is ignored. To address this problem, a hyperspectral image classification algorithm based on semi-supervised spatial-spectral local discriminant analysis (S3ELD) In traditional hyperspectral image classification algorithm based on feature extraction, spectral information is usually considered while spatial information is ignored. To address this problem, a hyperspectral image classification algorithm based on semi-supervised spatial-spectral local discriminant analysis (S3ELD) and spatial-spectral nearest neighbor (SSNN) classifier is proposed in this paper. Combining the spatial consistency of hyperspectral images and on the basis that the discriminant information of the labeled samples is used to maintain the separability of the data set, we define the spatial local pixel scatter matrix to preserve the spatial-domain neighborhood structures of pixel. A similarity measure method based on the spatial-spectral distance is then proposed to discover the local manifold structure and to construct SSNN. S3ELD algorithm not only reveals the local geometric relations of the data set but also enforces the compactness of the spectral-domain same class pixels and the spatial-domain local neighbor pixels in the low-dimension embedding space. Combining SSNN to classify, the classification accuracy is further enhanced. The experiments on the PaviaU and Salinas data sets show that the overall classification accuracy of S3ELD algorithm reaches 92.51% and 96.29%, respectively. Compared with several existing algorithms, the proposed algorithm can efficiently extract the information of discriminant characteristics and obtain higher classification accuracy..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 728002 (2017)
Shape Estimation Evaluation of Extended Objects Based on Modified Hausdorff Distance
Sun Lifan, Zhang Sen, Ji Baofeng, and Pu Jiexin
In order to verify the validity of extended objects tracking algorithm under high precision sensors measurement, it is often necessary to compare with other algorithms and evaluate its estimated performance. Unlike classical point objects, the main task of extended objects tracking is not only to estimate the motion stIn order to verify the validity of extended objects tracking algorithm under high precision sensors measurement, it is often necessary to compare with other algorithms and evaluate its estimated performance. Unlike classical point objects, the main task of extended objects tracking is not only to estimate the motion state of the objects, but also more importantly to accurately estimate their shape. As a result, there is an urgent need to the shape estimation performance evaluation of the extended objects. Aiming at the two kinds of representative extended target models based on star-convex and support functions, considering their different morphological parameters, an improved Hausdorff distance with different mathematical forms is proposed. Simulation results demonstrate that the modified Hausdorff distance can be used as an effective metrics to evaluate the shape estimation performance of the extended targets effectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 728003 (2017)
Scattering
Pulse Delay and Broadening of Laser Signal in Sand and Dust Weather
Wang Huiqin, Yao Yu, and Cao Minghua
Expressions of laser signal pulse delay and broadening in the sand and dust weather are derived when we use the small angle approximation and apply the modified two term Henyey-Greenstein (TTHG) scattering phase function to the electron scattering theory. Variations in pulse delay and broadening with atmospheric visibiExpressions of laser signal pulse delay and broadening in the sand and dust weather are derived when we use the small angle approximation and apply the modified two term Henyey-Greenstein (TTHG) scattering phase function to the electron scattering theory. Variations in pulse delay and broadening with atmospheric visibility, and the effects of scattering albedo, scattering coefficient and asymmetric factor on pulse delay and broadening are studied. Moreover, the changes of pulse delay and broadening with transmission distance under different wavelengths are analyzed. The results show that in the sand and dust weather with low visibility, the pulse delay and the broadening increase with the increasing of transmission distance, scattering albedo and scattering coefficient, and decrease with the increasing of atmospheric visibility. Particularly, when the atmospheric visibility increases to 3.5 km, the pulse delay and the broadening gradually approach to wavelength-related stable values. In addition, with the increasing of laser signal wavelength and sand asymmetric factor, the decreasing of pulse delay and broadening follows the negative exponential distribution..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 729001 (2017)
Spectroscopy
Denoising Method of Spectral Signal with Multiplicative and Additive Mixed Random Noises
Chen Zhengwei, Zhang Fang, Zhou Yang, and Huang Huijie
An analysis model for mixed multiplicative and additive noise of spectral signal is built, and an algorithm combining Wiener filtering and homomorphic filtering is proposed to denoise the spectral signal. Simulation results show that the proposed algorithm has better performance than moving average algorithm, least meaAn analysis model for mixed multiplicative and additive noise of spectral signal is built, and an algorithm combining Wiener filtering and homomorphic filtering is proposed to denoise the spectral signal. Simulation results show that the proposed algorithm has better performance than moving average algorithm, least mean square algorithm and recursive least square algorithm. Experimental results indicate that the noise in xenon lamp spectral signal matches the mixed multiplicative and additive model. Compared with moving average algorithm, least mean square algorithm, and recursive least squares algorithm, after the mercury lamp spectral signal is processed by the proposed algorithm, more stable characteristic spectral parameters can be extracted, such as peak and valley locations, peak amplitude and full width at half maximum. Better result can be obtained in quantitative analysis with the proposed algorithm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 730001 (2017)
Inversion Method of Plant Photosynthesis Parameter Based on Fast Phase and Relaxation Fluorescence Kinetics
Qin Zhisong, Zhao Nanjing, Yin Gaofang, Shi Chaoyi, Gan Tingting, Xiao Xue, Duan Jingbo, Zhang Xiaoling, Chen Shuang, Liu Jianguo, and Liu Wenqing
According to the biological film energy flow theory and electron transfer model, the plant complex photosynthesis is analyzed and simplified by combining to the exciting conditions of fast phase and relaxation, so that an inversion method of plant photosynthesis parameter is proposed .The maximum fluorescence yield is According to the biological film energy flow theory and electron transfer model, the plant complex photosynthesis is analyzed and simplified by combining to the exciting conditions of fast phase and relaxation, so that an inversion method of plant photosynthesis parameter is proposed .The maximum fluorescence yield is calculated by using the determinate method of sliding window slope. The photochemical quantum efficiency and the functional absorption cross section are obtained by analyzing the fast phase fluorescence process with linear least square algorithm. The plastoquinone average reduction time constant is obtained by analyzing the relaxation fluorescence process with discrete iterative algorithm. The experimental measurement results of the merismopedia and scenedesmu sobliquus grew in logarithmic phase and under the copper ion stress conditions show that the inversion has good stability and repeatability. The relative standard deviation of the photochemical quantum efficiency, the functional absorption cross section and the plastoquinone average reduction time constant are 1.25%, 1.50% and 1.83%, respectively. The linear correlation coefficient of the photochemical efficiency compared to the measuring result of the pulse amplitude modulation technology is 0.9714. The proposed inversion method provides an optical analysis means for the study of plant physiology..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 730002 (2017)
Three-Dimensional Fluorescence Characteristics by Parallel Factor Method Coupled with Self-Organizing Map and Its Relationship with Water Quality
Wang Juan, Zhang Fei, Wang Xiaoping, Yang Shengtian, and Chen Yun
Using three-dimensional fluorescence technique for water quality monitoring has great significance to manage the river water quality in oases of arid areas. The major objectives of this study are to apply parallel factor (PARAFAC) method and self-organizing map (SOM) to assessing fluorescence properties, and to charactUsing three-dimensional fluorescence technique for water quality monitoring has great significance to manage the river water quality in oases of arid areas. The major objectives of this study are to apply parallel factor (PARAFAC) method and self-organizing map (SOM) to assessing fluorescence properties, and to characterize and quantify the relationship between fluorescence and water quality indexes in the Ebinur Lake watershed. Fluorescence components are identified by the PARAFAC in the Ebinur Lake watershed. C1 corresponds to ultraviolet humic-like fulvic acid and C2 corresponds to humic-like fulvic acid. C3 includes two peaks, C3(T1) and C3(T2), C3(T1) corresponds to protein-like substance and C3(T2) corresponds to humic-like acid. C4 corresponds to humic-like substance. SOM technique is employed for the exploratory analysis of fluorescence components of water samples in the Ebinur Lake watershed. Discussing the distribution of water quality parameters in different clustering layers shows that the water quality tends to be better as a sequence of Bortala River upstream, JingHe Oasis, farmland surrounding Wusu, and Ebinur Lake nearby. There exist certain relationships between water quality indicators and fluorescence peaks. In wet season, the pH, electricity conductivity (EC), dissolved oxygen (DO), chemical oxygen demand (COD) and biological oxygen demand in five days (BOD5) have significant correlations with fluorescence peaks, while the total phosphor (TP), total nitrogen (TN) and NH+3-N have weak correlations with fluorescence peaks. Multiple linear regression equations are established between the pH, EC, DO, COD, BOD5 and fluorescent components, and correlation coefficients R are 0.579, 0.632, 0.502, 0.762 and 0.785, respectively. In general, based on the investigation of the fluorescence characteristics using PARAFAC, the SOM network can be used as an effective tool for analyzing water fluorescence spectra, and it can help to provide a scientific basis for water quality monitoring and river pollution controlling in arid regions..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 730003 (2017)
Ultrafast Optics
First-Order Time Differentiation Experiment of Femtosecond Optical Pulse Electric Field Envelope
Zhou Conghua, Li Baihong, Xiang Xiao, Wang Shaofeng, Dong Ruifang, Liu Tao, and Zhang Shougang
The light pulse differentiation technology in time domain has shown important applications in the field of time-space metrology, and it makes the measurement precision reach or beyond the standard quantum limit. In this paper, a first-order differentiation experiment of the pulse electric field envelope with a central The light pulse differentiation technology in time domain has shown important applications in the field of time-space metrology, and it makes the measurement precision reach or beyond the standard quantum limit. In this paper, a first-order differentiation experiment of the pulse electric field envelope with a central wavelength of 813 nm and pulse duration of 130 fs has been implemented based on the birefringent crystal and the Fourier pulse shaping system separately. Based on birefringent crystals, the pulse electric field envelop is achieved with energy conversation efficiency of 0.36%. By comparing the spectral distribution of the shaped pulse with the theoretical value, we find that a relatively good overlap can be seen within the full wavelength half maximum range near the central wavelength with an overlap rate of 91.36%, and the difference between them increases as the distance from the central frequency increases. For the first-order differentiated pulse electric field envelope generated by the Fourier pulse shaping system, the energy conversation efficiency rises to 11.10%. Meanwhile, its overlap rate with the theoretical value is over 98.37% within the effective modulation range of the utilized spatial light modulator. Compared with the former method, the latter can achieve much higher energy conversation efficiency and larger overlap spectral range with the theoretical value. Furthermore, as it can be used to achieve random-order differentiated pulses, the Fourier pulse shaping system can meet the demand of high-precision time synchronization applications..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 7, 732001 (2017)
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