Contents
2017
Volume: 37 Issue 1
45 Article(s)
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Stereoscopic Display Image Depth Adjustment Based on Visual Saliency
Xia Zhenping, and Cheng Cheng
In the stereoscopic display system based on binocular parallax, the improper depth distribution is the main cause of eye fatigue, therefore a novel stereoscopic depth adjustment method is proposed to improve the visual comfort. The proposed method takes the original stereoscopic image as the input. The visual saliency In the stereoscopic display system based on binocular parallax, the improper depth distribution is the main cause of eye fatigue, therefore a novel stereoscopic depth adjustment method is proposed to improve the visual comfort. The proposed method takes the original stereoscopic image as the input. The visual saliency map is derived from original stereoscopic image by applying spectral residual extracting method. Combined with the specific viewing condition, a visual fatigue index model is established to calculate the location of optimum zero disparity plane (ZDP) for specific image in specific viewing condition. The original input stereoscopic image is adjusted according to the optimum ZDP to derive the output stereoscopic image with the minimum visual fatigue index. In order to verify the improvement on visual comfort of the proposed depth adjustment method, the visual perception experiment is designed and implemented. Experimental result indicates that the proposed method significantly improves the stereoscopic viewing comfort..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 133001 (2017)
Fabric Image Registration Based on Affine Transform and Levenberg-Marquardt Algorithm
Zhang Biao, Zou Zhe, Chen Shujie, Shen Huiliang, Shao Sijie, and Xin Haozhong
In order to solve the problem of color difference analysis for textile fabric images captured by a multispectral system, a new method of image registration based on affine transform and Levenberg-Marquardt (LM) algorithm is proposed. In a registration perspective, the standard image and the batch image are first matcheIn order to solve the problem of color difference analysis for textile fabric images captured by a multispectral system, a new method of image registration based on affine transform and Levenberg-Marquardt (LM) algorithm is proposed. In a registration perspective, the standard image and the batch image are first matched by the proposed method and then taken for analysis of color difference. The deformation of the textile image captured by the multispectral system, including translation, rotation, scaling and shearing, conforms to the classic model of affine transform. To estimate the transform matrix, the proposed method first calculates the integral curves of the log-polar magnitude spectra of the two images for mapping. The original problem of solving the transform matrix is then converted to a numerical problem of nonlinear least squares fitting where the LM algorithm is employed for optimal value searching. Besides, the block registration is introduced to achieve more accurate registration. Experimental results show better registration accuracy of the proposed algorithm compared with the traditional Fourier-Mellin algorithm as well as the scale invariant feature transform based feature point matching method. It also solves the registration problem for textile images with periodic patterns effectively, which contributes to the following process of color difference evaluation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 133002 (2017)
Evaluation and Optimization of Flicker in Solid-State 3D Volumetric Display
Fang Yong, Lu Yunlong, Wu Huaxia2, Lü Guoqiang, and Hu Yuehui
To evaluate and optimize the flicker visibility in solid-state 3D volumetric display, a interlaced scanning refresh method of shutter array is proposed. Frequency domain energy distribution of the imaging light signal in different scanning modes is analyzed through Fourier transformation. Based on the temporal contrastTo evaluate and optimize the flicker visibility in solid-state 3D volumetric display, a interlaced scanning refresh method of shutter array is proposed. Frequency domain energy distribution of the imaging light signal in different scanning modes is analyzed through Fourier transformation. Based on the temporal contrast sensitivity function weighted amplitude(CSWA) model, the method of temporal contrast sensitivity function weighted amplitude contrast(CSWC) is proposed. Meanwhile, Pearson correlation coefficient between two visual perception experiment results and the estimation result of CSWC model is -0.99, which shows that the proposed method could reduce flicker visibility, and the proposed CSWC evaluation model realizes objective evaluation of the flicker in solid-state 3D volumetric display. The result can guide and facilitate the flicker optimization in 3D display based on the depth-fused principle and the improvement of visual comfort..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 133003 (2017)
Atmospheric Optics and Oceanic Optics
Background and Stochastic Terms of Optical Turbulence Profile Based on Ensemble Empirical Mode Decomposition
Chen Xiaowei, Li Xuebin1, Sun Gang, Liu Qing, Zhu Wenyue, and Weng Ningquan
Knowledge of distribution of atmospheric optical turbulence in propagation path is indispensable to evaluate the optical propagation effects accurately. Vertical profiles of optical turbulence strength are obtained from balloon flights. The data are decomposed into intrinsic mode functions on different scales by ensembKnowledge of distribution of atmospheric optical turbulence in propagation path is indispensable to evaluate the optical propagation effects accurately. Vertical profiles of optical turbulence strength are obtained from balloon flights. The data are decomposed into intrinsic mode functions on different scales by ensemble empirical mode decomposition. The quasi-cyclical variations on different components as well as their contribution to entire profile are analyzed. The results show that the cyclical scale within some intrinsic mode components is confirmed passing the statistical significance. Variance contribution rates show that the overall trend and stochastic intense noise are the main cause for the optical turbulence variation. A signal-filtering method based on consecutive mean square error is used to separate the profile into background and stochastic term. Correlation analysis of background and statistical mean show that the correlation coefficient is larger than 0.99. Analysis of stochastic term indicates that the optical turbulence profile is nonstationary series with multifractal structure..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 101001 (2017)
Study on Two Monte Carlo Simulation Programs of Polarization Lidar Depolarization by Water Cloud
Sun Xianming, Wang Haihua, and Shen Jin
The lidar returns exist a depolarization signal in water clouds due to the occurrence of multiple scattering when detecting water clouds. There exist some relationships between depolarization ratio and the microphysics characteristics of water clouds, and they can be used to retrieve the microphysics characteristics ofThe lidar returns exist a depolarization signal in water clouds due to the occurrence of multiple scattering when detecting water clouds. There exist some relationships between depolarization ratio and the microphysics characteristics of water clouds, and they can be used to retrieve the microphysics characteristics of water clouds. However, the relationships must be studied and explored by theoretical simulations. An important method used to simulate the lidar depolarization is Monte Carlo method. Two Monte Carlo simulation programs based on different ideas are given. The first approach is based on tracking the meridian plane described by the photon direction vector and the Z-aixs after each scattering step, and the polarization relative to the new meridian plane is described by the Stokes vector. The second approach is based on the following idea, the polarization state of the photon is described by a triplet of unit vectors rotated by an azimuth and scattering angle after each scattering step so as to track the polarization state change of the photon. A detailed simulation process is given for each approach, and the depolarization ratio for a type of water clouds is calculated using these two approaches. The simulation results show that the results calculated by the two Monte Carlo methods are in good agreement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 101002 (2017)
Study on the Effect of Inhomogeneous Aerosol Fields on Radiative Transfer Process in Near-Infrared Band
Chen Ming, Hu Shuai, Gao Taichang, Li Hao, Cheng Tianji, Liu Lei, and Yu Xuefeng
To investigate the influence of inhomogeneous aerosol field on radiative transfer process in near-infrared band, representative inhomogeneous aerosol fields are constructed, and the radiance, polarized radiance and flux density of the diffuse light are simulated by the radiative transfer model spectral harmonics discreTo investigate the influence of inhomogeneous aerosol field on radiative transfer process in near-infrared band, representative inhomogeneous aerosol fields are constructed, and the radiance, polarized radiance and flux density of the diffuse light are simulated by the radiative transfer model spectral harmonics discrete ordinary method (SHDOM) for different aerosol fields. In addition, the simulation error caused by taking the inhomogeneous aerosol fields as plane-parallel ones is analyzed numerically as well. Simulation results indicate that, inhomogeneous distribution of the aerosol particles has significant influence on the radiative transfer, and the simulation error of the polarized radiance caused by the inhomogeneity of the aerosol field is higher than that of radiance, where the simulation error of radiance and polarized radiance can reach 9.8% and 80%, respectively. Horizontal inhomogeneity of the aerosol field has a great influence on the simulation error distribution of radiance and polarized radiance, while the vertical inhomogeneity has a more notable effect on the radiative transfer process and has no significant influence on the distribution. As the aerosol concentration increases, simulation error caused by the inhomogeneity of aerosol fields gradually decreases. The simulation error of flux density is smaller than that of radiance and polarized radiance in magnitude, which is less than 5% for most case. It is also found that the variation of the simulation error with height shows specific distribution characteristics. This work will be helpful for both the determination of applicable scope of the plane-parallel atmospheric radiative transfer models and the estimation of error caused by the aerosol field inhomogeneity in remote sensing process..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 101003 (2017)
Simulation of Atmospheric Turbulence Phase Screen Based on Wavelet Analysis
Feng Fan, and Li Changwei
The fast simulation for atmospheric turbulence phase screen with large size and high resolution is essential to verify the performance and the control algorithm stability of the adaptive optical system in laboratory. A scheme of simulating atmospheric turbulence phase screen based on wavelet analysis is proposed. AccorThe fast simulation for atmospheric turbulence phase screen with large size and high resolution is essential to verify the performance and the control algorithm stability of the adaptive optical system in laboratory. A scheme of simulating atmospheric turbulence phase screen based on wavelet analysis is proposed. According to the frequency band segmentation of discrete wavelet transform, the Von Karman power spectrum is cut. The approximate high frequency coefficients of corresponding frequency bands at different scales are generated based on the energy conservation principle. The correlation function of low frequency coefficient of the top level is obtained when we use the recursive relations among the low frequency coefficients of wavelet layers, and the correlation function method is used to simulate low frequency coefficients. The final atmospheric turbulence phase screen is synthesized by the wavelet synthesis algorithm. Numerical simulation results show that the atmospheric turbulence phase screen generated based on wavelet analysis is consistent with the Von Karman model. The computational complexity of the proposed method is low, and it can quickly simulate atmospheric turbulence phase screen with large size and high resolution..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 101004 (2017)
Intensity Distribution of Partially Coherent Off-Axis Vortex Beam Propagating in Atmospheric Turbulence
Ke Xizheng, and Wang Chaozhen
Based on the generalized Huygens-Fresnel principle and the cross spectral density function, we deduce the expression of intensity distribution of partially coherent off-axis vortex beams propagating in atmospheric turbulence by using the Kolmogorov turbulence spectrum. The effects of off-axial distance, topological chaBased on the generalized Huygens-Fresnel principle and the cross spectral density function, we deduce the expression of intensity distribution of partially coherent off-axis vortex beams propagating in atmospheric turbulence by using the Kolmogorov turbulence spectrum. The effects of off-axial distance, topological charge, waist width, coherent length, transmission distance, turbulence intensity on the intensity distribution are discussed. Simulation results show that the topological charge does not change the position of the dark core. The sign of off-axial distance determines the direction of the dark core movement and the direction in which the intensity is concentrated. The upward movement distance of the core decreases with the increase of the waist width and the coherent length, and increases with the increase of the transmission distance and the turbulence intensity. The spreading of beam increases with the increase of the waist width, the coherent length, the transmission distance and the turbulence intensity..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 101005 (2017)
Detection of Adaptive Optics Celestial Targets Under Strong Skylight Background Based on Over-Complete Dictionary
Zhang Yanyan, Sun Yuanliang, Gong Xin, and Mei Yong
Aiming at the detection of celestial targets under strong skylight background using sparse domain, the over-complete dictionary of skylight background and target signal is established respectively to distinguish the skylight background area and target area, which based on the difference between skylight background and Aiming at the detection of celestial targets under strong skylight background using sparse domain, the over-complete dictionary of skylight background and target signal is established respectively to distinguish the skylight background area and target area, which based on the difference between skylight background and target signal in their morphological components. The signal energy is accumulated while in suppressing the background, and the signal to noise ratio is also improved. Simulation and experimental results show that the target can be well subtracted, while the centroid deviation, the root mean square and peak-valley values of the centroid are small compared with the subtracting threshold method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 101006 (2017)
Fiber Optics and Optical Communications
Performance Improvement Method of Rayleigh Brillouin Optical Time Domain Analysis System
Li Yongqian, Zhang Lixin, Li Xiaojuan, and Yang Runrun
The technique of multi-wavelength laser source is introduced into Rayleigh Brillouin optical time domain analysis system, in which multi-wavelength Rayleigh back-scattering generated by the 1st-order side-band of suppressed carrier microwave-modulated multi-wavelength pulse base is used as probe light to interact with The technique of multi-wavelength laser source is introduced into Rayleigh Brillouin optical time domain analysis system, in which multi-wavelength Rayleigh back-scattering generated by the 1st-order side-band of suppressed carrier microwave-modulated multi-wavelength pulse base is used as probe light to interact with the multi-wavelength sensing pulse through stimulated Brillouin scattering (SBS). The interaction can effectively improve the fiber SBS threshold, SBS interaction efficiency, and measurement precision of signal-to-noise ratio and Brillouin frequency shift. The generation principle of the multi-wavelength laser source by phase modulator and the exciting source of multi-wavelength Stokes light and anti-Stokes light used as probe light in the system by electro-optic intensity modulator is analyzed. The multi-wavelength Rayleigh Brillouin optical time domain analysis system is characterized by modeling analysis, in which the relationship between the signal-to-noise ratio and the wavelength number is achieved. Then a fiber SBS threshold measurement system and a Rayleigh Brillouin optical time domain analysis system using single-wavelength and three-wavelength laser sources are designed and the fiber SBS threshold and the system performance are tested. Experimental results show that when the fiber length is 2.4 km, the sensing pulse is with a width of 100 ns and a power of 100 mW, and the pulse base is with a power about 1.3 mW for each wavelength component in the single-wavelength and the three-wavelength systems, the fiber SBS threshold and signal-to-noise ratio in three-wavelength sensing system are approximately to be as high as 3 times and 2.83 times than that in single-wavelength sensing system, respectively. And within 2 km fiber length, the Brillouin frequency shift fluctuation decreases from 33.4 MHz in single-wavelength sensing system to 15.6 MHz in three-wavelength sensing system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 106001 (2017)
Fabrication of Chirped and Tilted Fiber Bragg Gratings and Investigation of Raman Filtering Effect
Zhang Yujing, Wang Meng, Wang Zefeng, Cao Jianqiu, and Xiao Hu
Stimulated Raman scattering (SRS) is one of the important factors which restrict the further improvement of fiber laser power. We propose that using chirped and tilted fiber Bragg gratings (CTFBGs) can suppress SRS. According to the design of optical fiber laser SRS signal of 1018 nm, a CTFBG of 1066 nm is fabricated. Stimulated Raman scattering (SRS) is one of the important factors which restrict the further improvement of fiber laser power. We propose that using chirped and tilted fiber Bragg gratings (CTFBGs) can suppress SRS. According to the design of optical fiber laser SRS signal of 1018 nm, a CTFBG of 1066 nm is fabricated. An experimental system is established to verify the filtering effect of Raman signal. Results show that the designed CTFBG can suppress the first-order SRS signal about 20 dB, and achieve a good effect. The research results have certain significance for suppressing SRS in high power fiber laser oscillator and amplifier with CTFBG, and for further improving the efficiency and output power of fiber lasers..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 106002 (2017)
Fiber Length Measurement Method Based on Sagnac Interferometer
Zheng Xiangliang, Sun Quanshe, Han Zhong, Liu Zhiming, and Zhao Facai
The measurement accuracy requirement for fiber length is higher and higher in the new generation fiber sensing system. A fiber length measurement method based on Sagnac interferometer is proposed. The basic principle and the experimental setup of the proposed method are introduced. Experiments of fiber length measuremeThe measurement accuracy requirement for fiber length is higher and higher in the new generation fiber sensing system. A fiber length measurement method based on Sagnac interferometer is proposed. The basic principle and the experimental setup of the proposed method are introduced. Experiments of fiber length measurement are conducted. The influences of polarization state of light source and fiber disturbance on measurement results are verified. Results show that the measurement accuracy of the proposed method can reach centimeter scale and the measurement range is from 1 km to 10 km..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 106003 (2017)
Data Recovery Technique for Asynchronous Sampling Signal Modulated by Optical Pulse Position Based on Pulse Broadening Waveform
Xiang Jinsong, Wang Ju, Wu Tao, and Zhang Xuewang
A data recovery scheme, which combines the pulse broadening wave shape interpolation with the pulse broadening effect compensation, is proposed. The scheme can realize interpolation and pulse broadening effect compensation at the same time according to the weight coefficient, solve the problems of time slot sampling erA data recovery scheme, which combines the pulse broadening wave shape interpolation with the pulse broadening effect compensation, is proposed. The scheme can realize interpolation and pulse broadening effect compensation at the same time according to the weight coefficient, solve the problems of time slot sampling error and jitter, and achieve data recovery of time slot signal modulated by pulse position. The simulation results indicate that the proposed scheme has a good robustness, and can solve the problems of time slot sampling error and jitter effectively. Under the condition that the jitter parameters used in decoding mismatch with the actual parameters, the performance of the proposed scheme is still better than the scheme in which the interpolation and the pulse broadening effect compensation are separated. For the proposed scheme combines the interpolation with the pulse broadening effect compensation, the computation is simplified..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 106004 (2017)
Blind Phase Noise Compensation in Large Linewidth Coherent Optical Orthogonal Frequency Division Multiplexing Systems
Ren Hongliang, Kang Shaoyuan, Lu Jin, Guo Shuqin, Qin Yali, and Hu Weisheng
A blind inter-carrier interference (ICI) phase noise compensation algorithm, which can solve the problem of symbol decision error effectively, is proposed based on the large linewidth coherent optical orthogonal frequency division multiplexing (CO-OFDM) system. Before using the proposed algorithm, we use the non-iteratA blind inter-carrier interference (ICI) phase noise compensation algorithm, which can solve the problem of symbol decision error effectively, is proposed based on the large linewidth coherent optical orthogonal frequency division multiplexing (CO-OFDM) system. Before using the proposed algorithm, we use the non-iterative blind (IFB) algorithm to compensate phase noise of common phase error (CPE). The proposed algorithm uses the cost function which is with simple form, so the computational complexity reduces significantly. The ICI phase noise compensation algorithm includes coarse ICI phase noise compensation and fine ICI phase noise compensation. Firstly, the average-power blind (Avg-BL) algorithm is implemented in the coarse ICI phase noise compensation, and then the common phase error compensation (CPEC) algorithm is implemented in the fine ICI phase noise compensation. A decision process will be performed by CPEC algorithm for the frequency-domain signals after the coarse ICI phase noise compensation. Every received OFDM symbol is separated into several sub-symbols in time-domain, and the approximate average value of phase noise of every sub-symbol is calculated. The sign decision error propagation problem in CPEC algorithm is solved when we use the Avg-BL algorithm. When the number of sub-symbols separated from OFDM symbol in time-domain is large, the CPEC algorithm can achieve the desired compensation performance for ICI phase noise. For the 50 Gbit/s CO-OFDM system with 100 km transmission distance, the numerical simulation is performed. The simulation results show that, compared with the other phase noise compensation algorithms, such as the Avg-BL algorithm and the CPEC algorithm, the proposed algorithm has good phase noise compensation performance with high spectral efficiency. With the suitable number of OFDM sub-symbols in time-domain, the proposed algorithm can obtain better compensation performance, and its complexity does not increase significantly..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 106005 (2017)
PAPR Reduction in Optical OFDM Systems Based on Swarm Intelligence Algorithms
Liu Jianfei, Wang Shaoying, Zeng Xiangye, Lu Jia, and Wang Mengjun
Aiming to reduce peak-to-average power ratio (PAPR) in coherent optical orthogonal frequency division multiplexing (OFDM) systems, several swarm intelligence algorithms are investigated, including particle swarm optimization algorithm (PSO), bat algorithm (BA) and birds swarm algorithm (BSA), and these algorithms can bAiming to reduce peak-to-average power ratio (PAPR) in coherent optical orthogonal frequency division multiplexing (OFDM) systems, several swarm intelligence algorithms are investigated, including particle swarm optimization algorithm (PSO), bat algorithm (BA) and birds swarm algorithm (BSA), and these algorithms can be used for optimizing the sub-carrier phase of OFDM symbols. Moreover, BA and BSA are modified by changing cognitive coefficient and learning factor dynamically. The simulation is carried out in a 100 Gb/s, binary quadrature amplitude modulated (4QAM) coherent optical OFDM system and the results show that PSO, BA and BSA can effectively reduce PAPR of the system, and the PAPRs for the modified BSA and the modified BA can be reduced by about 5.11 dB and 5.48 dB, respectively, compared with that of the original OFDM. The modified intelligence algorithms show better performance. The intelligence algorithms can also improve the bit error ratio performance, and the performance improvement is more obvious when the optical signal to noise ratio increases..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 106006 (2017)
Study on Fluorescent Radiation Excited by Evanescent Field in a Microfluidic Channel
Zhang Yuanxian, Chu Yufei, and Pu Xiaoyun
A bare quartz optical fiber is embedded in a polydimethylsiloxane (PDMS) substrate microfluidic channel, pumped by a continuous wave laser along the fiber axis, and the dye fluorescence excited by evanescent field of the pump beam has been investigated. As the evanescent field of the pump beam is homogeneous along the A bare quartz optical fiber is embedded in a polydimethylsiloxane (PDMS) substrate microfluidic channel, pumped by a continuous wave laser along the fiber axis, and the dye fluorescence excited by evanescent field of the pump beam has been investigated. As the evanescent field of the pump beam is homogeneous along the fiber axis, it is found that the fluorescent emission from the rim of fiber is uniform along the microfluidic channel. The experimental results show that the fluorescent emission intensity strongly depends on the dye concentration and the refractive index of the dye solution, and with the increase of the dye concentration and the refractive index of dye solution, the emitted fluorescent intensity increases accordingly. The observed phenomena have been successfully explained based on the mechanism of evanescent wave pumping fluorescent radiation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 106008 (2017)
pH Sensor Based on Fiber Grating with Extremely Large Tilt Angle and Its Sensitivity Enhancement
Luo Binbin, Zou Wengen, Zhao Mingfu, Shi Shenghui, Zou Xue, Tang Bin, Liu Yong, Zhou Hui, Li Chengcheng, and Tian Xia
Aiming at the low response sensitivity and the cross sensitivity of fiber grating pH sensors, a pH sensor based on fiber grating with extremely large tilt angle (Ex-TFG) is proposed, and the sensor is coated with pH sensitive intelligent hydrogel. The responsive mechanism of the Ex-TFG pH sensor is studied theoreticallAiming at the low response sensitivity and the cross sensitivity of fiber grating pH sensors, a pH sensor based on fiber grating with extremely large tilt angle (Ex-TFG) is proposed, and the sensor is coated with pH sensitive intelligent hydrogel. The responsive mechanism of the Ex-TFG pH sensor is studied theoretically, factors affecting the sensor sensitivity are analyzed, and a method to improve the measurement sensitivity is presented. Combined with the unique response performance of pH sensitive intelligent hydrogel, sensors are designed and fabricated, and corresponding experiments are conducted as well. The experimental results show that, compared with the pH sensors based on fiber Bragg grating and long period fiber grating, the pH sensor based on Ex-TFG can effectively improve the pH response sensitivity (with maximum of -0.718 nm/pH) and expand the pH detection range. The measurement sensitivity of the pH sensor can be enhanced when we increase the coating thickness of hydrogel..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 106009 (2017)
Image Processing
Method of Image Restoration Directly Based on Spatial Varied Point Spread Function
Zhou Chenghao, Wang Zhile, and Liu Shangkuo
The acquisition of point spread function varying with space, the calculation model of deconvolution, the morbidness of inverse problem, and the renatured algorithm are solved using point interpolation method, cyclic matrix model, Laplace regularization and conjugate gradient iteration. Upon which, the image restorationThe acquisition of point spread function varying with space, the calculation model of deconvolution, the morbidness of inverse problem, and the renatured algorithm are solved using point interpolation method, cyclic matrix model, Laplace regularization and conjugate gradient iteration. Upon which, the image restoration algorithm with varying space is established and the basic model of image restoration is analyzed. At last, the image restoration algorithms with and without varying space are compared with simulation, the result shows that the image restoration algorithm with varying space is better than spatial invariant algorithm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 110001 (2017)
Imaging Systems
Optical Encryption Scheme with Double Secret Keys Based on Computational Ghost Imaging
Cao Fei, and Zhao Shengmei
One optical encryption scheme with double secret keys based on the Toeplitz matrix and axial distance in the computational ghost imaging (CGI) is proposed. In this scheme, multiple random speckle patterns can be obtained by the transmission of a single random phase mask in legitimate users. At the receiving terminal, tOne optical encryption scheme with double secret keys based on the Toeplitz matrix and axial distance in the computational ghost imaging (CGI) is proposed. In this scheme, multiple random speckle patterns can be obtained by the transmission of a single random phase mask in legitimate users. At the receiving terminal, the image is decrypted with compressive sensing technique. The numerical simulation and experimental results indicate that the authorized users can recover the original image completely, but the eavesdroppers cannot obtain any information of the original image even if the eavesdropping rate is up to 60%. The use of double secret keys can effectively improve the security of this scheme..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 111001 (2017)
Terahertz Non-Destructive Inspection of Air Defect Within Adhesive Layers of Multi-Layer Bonded Structure
Li Wenjun, Wang Tianyi, Zhou Yu, You Chengwu, Yang Zhengang, Wang Kejia, and Liu Jinsong
Three-layer bonded structure containing artificial air defects within adhesive layers is manufufactured with the usage of building materials, insulation mat, and adhesive, and the specimen is inspected by the SynViewScan 300 continuous terahertz imaging system. Via analysing the two-dimensional terahertz images at adheThree-layer bonded structure containing artificial air defects within adhesive layers is manufufactured with the usage of building materials, insulation mat, and adhesive, and the specimen is inspected by the SynViewScan 300 continuous terahertz imaging system. Via analysing the two-dimensional terahertz images at adhesive surface and single point longitudinal signal within defect area and normal adhesive area, the informations about position and size of air defects are acquired.The results indicate that the continuous terahertz imaging system is capable of clear identification of air defects within bonded structures..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 111002 (2017)
Gas Leak Infrared Image Dynamic Compression and Enhancement Method
Li Jiakun, Jin Weiqi, Zhang Xu, Jin Minglei, and Fan Yongjie
As the gas leak infrared imaging detection technology has significant advantages of high efficiency and remote imaging detection, in order to enhance the detail perception of observers and equivalently improve the detection limit, a novel gas leak infrared image compression and enhancement method based on bilateral filAs the gas leak infrared imaging detection technology has significant advantages of high efficiency and remote imaging detection, in order to enhance the detail perception of observers and equivalently improve the detection limit, a novel gas leak infrared image compression and enhancement method based on bilateral filtering is proposed. The method controls the process of the bilateral filtering, compressing and enhancing according to the characteristics of the gas leak infrared image. The experimental results demonstrate that the trace of gas leak is enhanced significantly, the contrast of the entire image is appropriate, and the halo effect is suppressed effectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 111003 (2017)
Instrumentation, Measurement and Metrology
Method of Measuring Gain and Readout Noise of Miniature Spectrometer
Xia Guo, Huang Chan, Wu Su, Jin Shiqun, and Xing Jinyu
Accurate measurement of the gain and readout noise is very important for the miniature spectrometer performance evaluation and the spectrum data processing. Based on the noise principle of miniature spectrometers, the function between the output signal and the noise is deduced, and a method of measuring the gain and thAccurate measurement of the gain and readout noise is very important for the miniature spectrometer performance evaluation and the spectrum data processing. Based on the noise principle of miniature spectrometers, the function between the output signal and the noise is deduced, and a method of measuring the gain and the readout noise of the miniature spectrometer is proposed. The measurement system is built according to the method. The gain of the self-developed miniature spectrometer is 2.02 e－/ADU, and the readout noise is 68.92 e－. Compared with the experimental results of the photon-transfer curve method and the measuring dark spectrum method, feasibility and effectiveness of the proposed method is further verified. The derivation process of this method is rigorous, and its operation process is simple. The method can be widely used in the measurement of gain and readout noise of the miniature spectrometer..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 112001 (2017)
New Method of Three-Dimensional Position Fast and Precision Measurement of Microspheres
Yao Chengwen, Lei Hai, Chang Xinyu, Hu Chunguang, Hu Xiaodong, Li Hongbin, and Hu Xiaotang
To achieve fast and accurate three-dimensional measurements of microspheres in liquid, especially axial tracking resolution and speed, this paper proposes a new measurement method based on off-focus measuring theory and combining quadrant interpolation algorithm and radial projection algorithm. Resolution of 1 nm measuTo achieve fast and accurate three-dimensional measurements of microspheres in liquid, especially axial tracking resolution and speed, this paper proposes a new measurement method based on off-focus measuring theory and combining quadrant interpolation algorithm and radial projection algorithm. Resolution of 1 nm measurement in 3D directions of microspheres is realized. The method has high measurement efficiency with the fastest measuring rate at individual particle axial position of hundred frames per second and more. The influences of horizontal deviations on axial measurements are further discussed, and axial resolution throughout dozens of micrometers is analyzed. Compared with the cross-correlation method under the same experimental conditions, this measurement method shows feasibility in practical measurement applications and enjoys higher measurement efficiency when achieving the same axial measurement resolution..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 112002 (2017)
Synchronous Phase Demodulation for Real-Time Absolute Distance Measurement Based on Optical Comb Multi-Wavelength Interferometry
Wang Guochao, Tan Lilong, Yan Shuhua, and Wei Chunhua
The advent of optical comb has brought technical innovation for large-scale and high-precision absolute distance measurement (ADM). The marvelous features of optical frequency facilitate the great development to the real time ADM based on multi-wavelength interferometry. To realize synchronous phase demodulation for inThe advent of optical comb has brought technical innovation for large-scale and high-precision absolute distance measurement (ADM). The marvelous features of optical frequency facilitate the great development to the real time ADM based on multi-wavelength interferometry. To realize synchronous phase demodulation for interference signals in real-time ADM based on optical comb multi-wavelength interferometry, we propose a multi-channel synchronous phase demodulation signal-processing method based on multi-wavelength heterodyne interferometry, and develope a related phase demodulation module. The wavelength de-multiplexing is conducted in the experiment. Performances of the multi-channel phasemeter, such as linear precision, stability and synchronization, are tested. The experimental analysis about the real-time synchronous phase demodulation for multi-wavelength interference signal is carried out, and the feasibility of realizing high-precision synchronous phase demodulation with the proposed method is verified..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 112003 (2017)
Optical Fabry-Pérot Cavity System with High Thermal Stability and High Finesse
Wang Xingchang, Li Shaokang, Li Gang, and Zhang Tiancai
An optical Fabry-Pérot cavity composed of ultra-low expansion glass material and a vacuum temperature control system are designed. The temperature of the Fabry-Pérot cavity can be precisely tuned from 10 ℃ to 40 ℃ when we use the double temperature control system, and the temperature fluctuation of the systemAn optical Fabry-Pérot cavity composed of ultra-low expansion glass material and a vacuum temperature control system are designed. The temperature of the Fabry-Pérot cavity can be precisely tuned from 10 ℃ to 40 ℃ when we use the double temperature control system, and the temperature fluctuation of the system is within ±0.004 ℃ in 24 h. The variations in resonant frequency of the F-P cavity and expansion coefficient of the cavity material with temperature are measured when we analyze the F-P cavity resonant frequency and the saturated absorption spectrum of Cs atom. The zero expansion temperature (29.286±0.057 ℃) is determined accurately when we fit the measured data. An optical frequency standard with thermal stability of 3.494×10-14 is expected to obtained by the proposed temperature control system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 112004 (2017)
Misalignment Analysis of Cylindrical Inner Surfaces in Interferometric Measurement
Sun Hao, Han Sen, Tang Shouhong, Wang Fang, and Yin Liuliu
Information of the entire cylindrical inner surfaces can be achieved by using a Fizeau interference system and a 90° conical mirror in a one-time measurement. In order to achieve high-precision surface measurement, the alignment of experimental apparatus is very crucial. However, defects of the alignment may causeInformation of the entire cylindrical inner surfaces can be achieved by using a Fizeau interference system and a 90° conical mirror in a one-time measurement. In order to achieve high-precision surface measurement, the alignment of experimental apparatus is very crucial. However, defects of the alignment may cause the spatial orientation of the cone mirror and the tested cylinder difficult to determine, and any misplacement from ideal location may result in large measurement errors. Therefore, to remove the system errors, the reasons of all kinds of misalignment should be well understood and their influences on the measurement results should be analyzed. By establishing the mathematical model in cylindrical coordinate, the change formula of offset error and rotational error is deduced. The formula is verified by numerical simulation of Matlab software and practical measurement. The results show that the misalignment error coefficient can be successfully derived with the proposed formula, which will further benefit system error correction..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 112005 (2017)
A Method for Large Distance Multi-Optical Axis Parallelism Online Detection
Chen Zhibin, Xiao Wenjian, Ma Dongxi, Qin Mengze, and Fan Lei
In order to satisfy the on-line detection of multi-optical axis parallelism for modern integrated photoelectric systems, a method of large distance multi-optical axis parallelism detection based on optical aiming and inertial measurement is proposed. An accurate and movable reference coordinate system is established byIn order to satisfy the on-line detection of multi-optical axis parallelism for modern integrated photoelectric systems, a method of large distance multi-optical axis parallelism detection based on optical aiming and inertial measurement is proposed. An accurate and movable reference coordinate system is established by an inertial sensor. The measured optical axes can be aimed and their vector coordinates in reference coordinate system can be measured by the measurement system. The angle between the measured optical axes can be calculated by their vector coordinates and then the parallelism of measured axes can be detected by their angle at the same time. A prototype of the measurement system is built and its measurement uncertainty is evaluated by the Monte Carlo method. The proposed method is experimentally verified through an actual test between laser rangefinder and infrared thermal imager. The test results show that the measurement error of the parallelism between sighting axis and laser emitting axis can reach 24.4″ and the measurement error of the parallelism between sighting axis and infrared axis can reach 27.0″. The proposed method expands measurement range and improves measurement efficiency by movable measurement. Therefore, it provides a method for large distance multi-optical axis parallelism on-line detection in the wild..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 112006 (2017)
Application of Narrow Linewidth Laser in Precision Measurement of Optical Resonator Cavity Length
Jiao Dongdong, Gao Jing, Deng Xue, Xu Guanjun, Dong Ruifang, Liu Tao, and Zhang Shougang
A new method for measuring cavity length of optical resonator is proposed by measuring the free spectral range of optical resonator and the intracavity resonance laser wavelength with narrow linewidth lasers as light sources. The measurement theory of optical resonator cavity length is strictly deduced, and the measureA new method for measuring cavity length of optical resonator is proposed by measuring the free spectral range of optical resonator and the intracavity resonance laser wavelength with narrow linewidth lasers as light sources. The measurement theory of optical resonator cavity length is strictly deduced, and the measurement conditions and results are analyzed and discussed by theoretical simulation. An optical resonator with cavity length about 100 mm is measured precisely with the developed narrow linewidth laser as light source, of which the linewidth is 1.9 Hz, the frequency instability is 1.7×10-14 s-1 and the central wavelength is 1550 nm. The free spectral region of the optical resonator is measured, and it is obtained that the cavity length of the optical resonator and the precision are 0.10024407 m and 22 nm, respectively. The intracavity resonance laser wavelength of the optical resonator is measured, and it is obtained that the cavity length of the optical resonator and the precision are 0.1002440884 m and 0.21 nm, respectively. The accuracy is improved by two orders of magnitude. The proposed method is expected to promote the development of basic physics research, physical properties precision measurement of materials, fiber sensing and so on..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 112007 (2017)
Lasers and Laser Optics
Depolarization Feature and Polarization Control in End-Pumped Nd∶YAG Slab Lasers
Wu Zhenhai, Xu Liu, Wang Juntao, Wang Dan, Zhou Tangjian, and Hu Hao
The depolarization feature in high power, end-pumped Nd∶YAG slab lasers is studied. The polarization control and depolarization compensation in high power slab laser output are realized with the usage of high power polarizer and 90°quartz rotator, which effectively improves the polarized output power and the unifoThe depolarization feature in high power, end-pumped Nd∶YAG slab lasers is studied. The polarization control and depolarization compensation in high power slab laser output are realized with the usage of high power polarizer and 90°quartz rotator, which effectively improves the polarized output power and the uniformity of the near-field light intensity distribution. The experimental results indicate that, via the optimization of depolarization compensation, the output power of linearly polarized laser is increased from 8.7 kW to 9.6 kW, and the depolarization rate is decreased from 30.8% to 3.1%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 114001 (2017)
Low-Stress Mounting Configuration Design for Large Aperture Laser Transmission Mirror
Zhang Zheng, Quan Xusong, Wang Hui, Yao Chao, and Rong Yiming
The large aperture laser transmission mirror is a crucial optical unit of the high power solid-state laser in the inertial confinement fusion (ICF) facility. Based on the engineering practice of the SG-Ⅲ facility, the technology status and key problems of the low-stress mounting configuration for the mirror are summariThe large aperture laser transmission mirror is a crucial optical unit of the high power solid-state laser in the inertial confinement fusion (ICF) facility. Based on the engineering practice of the SG-Ⅲ facility, the technology status and key problems of the low-stress mounting configuration for the mirror are summarized firstly. Then, a general mechanical model of the deformed mirror is built with the elastic mechanics theory. Furthermore, a brand new low-stress mounting configuration with flexure support is proposed and the mechanical properties of the flexure support are verified with the finite element method and field experiments. The new integrated mirror assembly is designed and the influence of mounting force on surface deformation under the current and the new technologies is studied by comparison. Finally, with combination of the new mounting configuration and the numerical decoupling method of stress-induced deformation, a promising process flow is discussed. The study is of great significance for solving the mounting-induced deformation of the large aperture optical devices, and is expected to provide effective and reliable technical schemes for constructing ICF facility of the next generation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 114002 (2017)
Machine Vision
Calibration and Rectification of Fisheye Images Based on Three-Dimensional Control Field
Pi Yingdong, Li Xin, Chen Zhiyong, and Wang Hongchen
The main distortions of fisheye images of a field view 180° are the distortion due to the spherical structure and optical distortion. A step-wise calibration method based on the three-dimensional control field is proposed, in which the relationship between 3D space and imagery space is constructed with direct lineThe main distortions of fisheye images of a field view 180° are the distortion due to the spherical structure and optical distortion. A step-wise calibration method based on the three-dimensional control field is proposed, in which the relationship between 3D space and imagery space is constructed with direct linear transformation (DLT), and the transformation radius associated with fisheye structure is calibrated with the iteration method combining the spherical perspective model. The distortion model is constructed based on the correction result of the first calibration, and introduced into DLT to calibrate the distortion parameters. The images are corrected again with the result of second calibration, which solves the serious distortion of fisheye images. The experiments verify the effectiveness and accuracy of the proposed method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 115001 (2017)
Visually Interactive Hand Tracking Algorithm Combined with Infrared Depth Information
Sun Jin, Ding Yonghui, and Zhou Lai
Hand tracking is the basis and core problem of vision interaction in virtual reality. Due to the poor performance resulted from the existing hand tracking methods in the instances of movement, scale change, complex background, etc., a new hand tracking algorithm is presented. The proposed algorithm is under particle fiHand tracking is the basis and core problem of vision interaction in virtual reality. Due to the poor performance resulted from the existing hand tracking methods in the instances of movement, scale change, complex background, etc., a new hand tracking algorithm is presented. The proposed algorithm is under particle filtering and tracking framework, which adopts oriented gradient local binary pattern descriptor integrating with texture and contour information. Furthermore, the infrared depth information is introduced. The proposed tracking algorithm combines the observation information of current frame in the stages of particle sampling and updating by the artificial bee colony algorithm, which overcomes the degeneracy problem in particle filtering and improves hand tracking precision by optimization of the space search. Experimental results show that the proposed algorithm can achieve accurate and robust hand tracking in complex background..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 115002 (2017)
Materials
Long Afterglow Characteristics of γ-Ray Irradiated SrAl2O4∶Eu2+,Dy3+ Phosphor
Yang Fang, Fu Renli, Tang Ye, Gu Xiguang, Liu Chao, and Cai Junde
To investigate the long afterglow properties of the samples, long persistence phosphors of SrAl2O4∶Eu2+,Dy3+ are successfully synthesized and the samples are irradiated by irradiation, which is from the 60Co~γ source and whose dose is accumulated to 100 kGy. The influence of irradiation on the properties of these two kTo investigate the long afterglow properties of the samples, long persistence phosphors of SrAl2O4∶Eu2+,Dy3+ are successfully synthesized and the samples are irradiated by irradiation, which is from the 60Co~γ source and whose dose is accumulated to 100 kGy. The influence of irradiation on the properties of these two kinds of phosphors is studied by comparing crystal structure, optical adsorption properties, decay curve and thermoluminescence (TL) characteristics of unirradiated and irradiated samples. X-ray diffraction (XRD), Raman spectrometer, ultraviolet visible spectrophotometer, fluorescence spectrophotometer and thermoluminescence spectrometer are used to investigate these properties. Conclusions from the present work can be briefly summarized as follows. In irradiated samples, the unit cell volume decreases and the concentration of oxygen vacancies increases after irradiation. The absorption intensity of irradiated samples rises because of more irradiation-induced defects introduced. The decay time is prolonged and the initial brightness is promoted after irradiation. Thermoluminescence studies reveal that thermoluminescence glow peak of irradiated sample shifts towards higher temperature and its intensity is improved greatly. It is calculated that the depth of traps increases 0.0039 eV after irradiation, which demonstrates that the irradiation not only affects the traps′ distribution but also increases the number of deeper traps..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 116001 (2017)
Optical Design and Fabrication
Optimized Design of Leveling and Focusing Servo Control System
Zong Yonghong, Zhou Changhe, Ma Jianyong, Wang Jin, and Lu Yancong
A leveling and focusing servo control system is built to improve the focus accuracy of the differential parallel confocal laser direct writing system. To obtain a detection curve with high sensitivity, accuracy and stability, the cylindrical lens as an astigmatism element is combined with four-quadrant photodetector, aA leveling and focusing servo control system is built to improve the focus accuracy of the differential parallel confocal laser direct writing system. To obtain a detection curve with high sensitivity, accuracy and stability, the cylindrical lens as an astigmatism element is combined with four-quadrant photodetector, and the differential astigmatism detection method and proportion integration differentiation(PID) feedback algorithms are employed to reduce errors caused by light source and external interference. By optimizing the optical parameters, the detection curve with high sensitivity and stability has been obtained, with a range of around 3 μm and a static focusing error of ±5.0 nm. The stretching of piezoelectric ceramic transducer(PZT) can be guaranteed within the depth of focus range in the dynamic mode. Nano-scale precision of the focal position can be achieved, and the tilt and pitch of lever adjuster approximate 0.01 mrad. Utilizing this system, gratings can be fabricated, and this system can provide reference for the fabrication of larger-size and higher-density gratings in the future..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 122001 (2017)
Phase Shift of Optical Fiber Sensor Coated with ZnO Based on Hybrid Particle Swarm Optimization Algorithm
Liu Qi, Zhou Li, and Zhou Ya
An optimization model for phase shift of transmission light in optical fiber sensor coated with ZnO is established, and the model is optimized by the hybrid particle swarm optimization algorithm. Simulation results show that the optimal value of phase shift of transmission light is obtained by the algorithm. The effectAn optimization model for phase shift of transmission light in optical fiber sensor coated with ZnO is established, and the model is optimized by the hybrid particle swarm optimization algorithm. Simulation results show that the optimal value of phase shift of transmission light is obtained by the algorithm. The effect of relevant parameters of the optical fiber sensor on phase shift of transmission light is analyzed. The theoretical value and the experimental value of phase shift are compared, and they are basically consistent..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 122002 (2017)
Diffractive Aspheric Contact Lens to Correct Myopic-Presbyopia
Jiang Lai, Liu Yongji, Wang Xiaolin, and Wang Zhaoqi
The myopia will suffer presbyopia with aging. A diffractive aspheric contact lens (CL) is designed, aiming to correct myopic-presbyopia with a pair of glasses. In this design, myopia is corrected by the aspheric surface of the CL and presbyopia is corrected by the diffractive rings. The CL is optimized based on a myopiThe myopia will suffer presbyopia with aging. A diffractive aspheric contact lens (CL) is designed, aiming to correct myopic-presbyopia with a pair of glasses. In this design, myopia is corrected by the aspheric surface of the CL and presbyopia is corrected by the diffractive rings. The CL is optimized based on a myopic-presbyopia eye model considering 2.00 diopters of myopia and an accommodation of 2 D. Five object locations covering a range from infinity to 250 mm are considered. The optical properties of the myopic-presbyopia eye model with CL of 0° and ±4° field of view are researched. As a result, with the CL, the visual acuity looking at different locations are in a range from 1.3 to 1.5 in photopic vision (2.8 mm pupil diameter), except slightly worse infinity visual acuity (0.9), and the visual acuity looking at different locations remains above 1.0 in mesopic vision (4.5 mm pupil diameter). Additionally, the aberrations, such as coma, astigmatism and distortion, of the central visual field are reasonable after CL is worn. Therefore, the designed CL provides high optical performance and visual performance for myopic-presbyopia at 0 D and 4 D as well as high optical performance at intermediate distances, and the imaging performance is almost unaffected by the pupil..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 122003 (2017)
Optical Devices
All-Optical Mass Sensing Based on Monolayer Molybdenum Disulfide Nanomechanical Oscillator
Chen Huajun, Li Yang, Chen Changzhao, Fang Xianwen, and Tang Xudong
A plate-like circular monolayer molybdenum disulfide (MoS2) nanomechanical oscillator system based on Si/SiO2 substrate is proposed. An all-optical method, which uses a strong pump laser and a weak detection laser effect on the oscillator system at the same time, is proposed to measure mechanical oscillator frequency. A plate-like circular monolayer molybdenum disulfide (MoS2) nanomechanical oscillator system based on Si/SiO2 substrate is proposed. An all-optical method, which uses a strong pump laser and a weak detection laser effect on the oscillator system at the same time, is proposed to measure mechanical oscillator frequency. The phenomenon of phonon-induced transparency is demonstrated in the system, and the physical interpretation is presented. By measuring the width between two peaks in the probe absorption spectrum, we find that the exciton-oscillator coupling strength is proportional to the width and the method can be used to measure the exciton-oscillator coupling strength. Further, an all-optical mass sensing scheme is proposed based on the nanomechanical oscillator system. By measuring the resonance frequency shift in optical spectrum, we can obtain the additional mass deposited on the surface of molybdenum disulfide oscillator directly. The simulation results show that the mass responsivity of the oscillator system is 2.32 Hz/ag. The monolayer molybdenum disulfide nanomechanical oscillator system may have potential applications in quantum sensing and all-optical MoS2-based devices..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 123001 (2017)
Optical Absorber from Surface Plasmonic Grating with Depth-Linear-Gradient Grooves
Liang Leixia, Xue Wenrui, and Yang Rongcao
A new kind of optical absorber based on surface plasmonic gratings with depth-linear-gradient grooves is designed. The effects of structural parameters and the light incident angle on the absorption characteristics within the visible wavelength range are analyzed by the finite element method. The proposed optical absorA new kind of optical absorber based on surface plasmonic gratings with depth-linear-gradient grooves is designed. The effects of structural parameters and the light incident angle on the absorption characteristics within the visible wavelength range are analyzed by the finite element method. The proposed optical absorber is also compared with other optical absorbers with symmetrical groove depths. Results indicate that, increasing the number of grooves, groove width, and groove depth of air grooves, as well as reducing the center distance of adjacent air grooves, all can effectively enhanced the light absorption efficiency. The absorption performance of optical absorber here is superior to that of other optical absorber with symmetrical groove depth..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 123002 (2017)
Optics in Computing
Ray Tracing Acceleration Structure Based on Octree Adaptive Volume Merging
Yuan Yuwei, Quan Jicheng, Wu Chen, Liu Yu, and Wang Hongwei
In order to overcome the problems of large amounts of calculation and low operating efficiency of ray tracing algorithm, a ray tracing acceleration structure based on the octree adaptive volume merging (OAVM) is proposed. Through gathering blank nodes of an octree model as a bounding volume adaptively, this structure cIn order to overcome the problems of large amounts of calculation and low operating efficiency of ray tracing algorithm, a ray tracing acceleration structure based on the octree adaptive volume merging (OAVM) is proposed. Through gathering blank nodes of an octree model as a bounding volume adaptively, this structure can reduce the intersection number between ray and blank nodes as much as possible. Based on the characteristic that OAVM is a multi-level octree structure, an algorithm with the Morton code to encode all the nodes at different levels is proposed. The storage method and neighborhood search algorithm used in this structure can reduce the amount of pointers and avoid the recursive search effectively. In the meanwhile, the algorithm deals with the problem of partial update a in large scale dynamic scene effectively. Based on the idea of Liang-Barsky algorithm, the calculation speed of intersection test for rays is improved. The experiment results indicate that, compared with traditional algorithms, the proposed algorithm can reduce the total number of pointers by 54.45% averagely. The time of ray intersection test is reduced by 52.37% averagely. The ray intersection test time is decreased and the scene rendering efficiency is improved..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 120001 (2017)
Remote Sensing and Sensors
Decoy Spectrum Design Based on Feature Space Significance
Li Shuying, Du Shanshan, and Zeng Zhaoyang
To deal with spectrum design for decoys under hyperspectral detection condition, the decoy spectrum design principles were analyzed in term of the feature significance. Different from other detection technologies, hyperspectral detection is a process of multi-dimensional data processing, and the target significance is To deal with spectrum design for decoys under hyperspectral detection condition, the decoy spectrum design principles were analyzed in term of the feature significance. Different from other detection technologies, hyperspectral detection is a process of multi-dimensional data processing, and the target significance is embodied in feature space formed by dimensionality reduced data. Correspondingly, the proposed spectrum design method for decoys is as follows. The decoy is set in feature space, highlighting itself and shielding real target, and then the spectrum of the decoy is reduced by the relative relation between the decoy and other targets in feature space. The reduction is based on the linear relation between the feature space axis and the original data channels. Target detection results verified the effectiveness of the proposed decoy spectrum design method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 128001 (2017)
Hyperspectral Real-Time Anomaly Target Detection Based on Progressive Line Processing
Zhao Chunhui, Deng Weiwei, and Yao Xifeng
Real-time processing can reduce the pressure of data storage and downlink transmission caused by the ever-expending hyperspectral dataset, which has received more and more attention in hyperspectral anomaly detection. Since acquiring data with pushbroom has become main stream for hyperspectral imaging sensors, a real-tReal-time processing can reduce the pressure of data storage and downlink transmission caused by the ever-expending hyperspectral dataset, which has received more and more attention in hyperspectral anomaly detection. Since acquiring data with pushbroom has become main stream for hyperspectral imaging sensors, a real-time anomaly target detection method is proposed based on the framework of progressive line processing. In order to make sure the causality of real-time processing, the local causal window model is introduced into the Reed-Xiaoli anomaly detection algorithm, and the sliding local causal window is used to detect anomaly targets. In terms of the high computational complexity caused by the inversion of matrix, the recursive principle of the Kalman filter and the Woodbury′s lemma are employed to update the status information of current data through iterating data status information at the previous moment, which avoids the inversion of large matrix. The simulated and real hyperspectral data are adopted for the experiment. The results show that under the premise of maintaining the detection accuracy, the proposed real-time algorithm improves the processing efficiency significantly compared with the original algorithm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 128002 (2017)
Check Analysis of In-Orbit Cross-Calibration Between FY-3A/TOU and Metop-B/GOME-2
Wang Houmao, Zhao Qichang, Wang Yongmei, Zhang Zhuo, Yang Xiaojun, and Hu Xiuqing
Ultraviolet total ozone unit (TOU) is one of the main payloads on FY-3A meteorological satellite and the first instrument for daily global coverage of total ozone monitoring is independently designed and manufactured by China. It has been in-orbit for almost seven years from May 2008 to March 2015. The preliminary studUltraviolet total ozone unit (TOU) is one of the main payloads on FY-3A meteorological satellite and the first instrument for daily global coverage of total ozone monitoring is independently designed and manufactured by China. It has been in-orbit for almost seven years from May 2008 to March 2015. The preliminary study shows that the radiation response FY-3A/TOU instrument is different for different spectrum bands ［the response of the instrument with radiance larger than 6.6 μW/(cm2·nm·sr) is obviously different from the instrument with radiance less than 6.6 μW/(cm2·nm·sr)］. It has the problem of bilinear response. A method is introduced for ultraviolet band in-orbit cross-calibration based on the data detected by global ozone monitoring experiment 2 (GOME-2) on European Metop-B satellite. The data of FY-3A/TOU L1B are checked by in-orbit cross-calibration, and then the rea-time comparisons and corrections of instruments′ detection values are made. The calibration results chosen from February 2013 to February 2015 indicate that the comparison slopes of radiation are all very close to 1 before August 2013, which mean that the detected radiance of TOU is fairly accurate. However, the slopes become a little larger after August 2013, the detected radiance of TOU is relatively larger than GOME-2, which means that the detected response FY-3A/TOU is changed. Although the equation slopes are variant, the relation coefficient between TOU and GOME-2 keeps better linear dependence (R2＞0.96). It means that the later measurements of TOU can be corrected by use of cross-calibration equation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 128003 (2017)
Spectroscopy
Experimental Measurement and Determination of Photoluminescence Lifetime of PbS Quantum Dots
Cheng Cheng, and Li Jiejie
The photoluminescence (PL) lifetimes of PbS quantum dots (QDs) with different sizes, temperatures, and backgrounds are determined by the measurements of absorption spectra, time-resolved PL spectra, and transmission electron microscopy (TEM) images of PbS QDs. An empirical formula describing the variation of the first The photoluminescence (PL) lifetimes of PbS quantum dots (QDs) with different sizes, temperatures, and backgrounds are determined by the measurements of absorption spectra, time-resolved PL spectra, and transmission electron microscopy (TEM) images of PbS QDs. An empirical formula describing the variation of the first absorption-peak wavelength with QD size is obtained. The results indicate that the PL lifetime is strongly correlated to QD size in a way of negative exponential-dependence; the lifetime is weakly dependent on temperature; background material can affect the lifetime due to the surface-polarization effect..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 130001 (2017)
Thin Films
Design of Thermochromic Smart Radiation Device Based on VO2 Phase Change
Jiang Wei, Li Yi, Chen Peizu, Wu Zhengyi, Xu Tingting, Liu Zhimin, Zhang Jiao, Fang Baoying, Wang Xiaohua, and Xiao Han
A smart radiation device (SRD) of VO2/Si3N4/Al structure with tunable emittance is designed. The optical properties of SRD are studied through the optical thin film characteristic matrix analytical method. The results show that emission properties of SRD are determined by the thickness of VO2 and the modulation wavelenA smart radiation device (SRD) of VO2/Si3N4/Al structure with tunable emittance is designed. The optical properties of SRD are studied through the optical thin film characteristic matrix analytical method. The results show that emission properties of SRD are determined by the thickness of VO2 and the modulation wavelength range is related to the thickness of Si3N4 dielectric layer. The emittance tunability of the optimized SRD is 0.38. The SRD with MgF2/Si3N4 bi-layer anti-reflection coating presents an emittance of 0.30 at 20 ℃ and 0.91 at 100 ℃, and the tunability is increased to 0.61. The finite difference time domain method is used to analyze the modulated radiation distribution of SRDs with or without anti-reflection coating. It is proved that the added anti-reflection coating can improve the emittance-switching efficiency of SRD and enhance its adaptability in complex environment. The method can give reference to the design of high performance SRD and meets the need for a lighter thermal control device of spacecraft..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 131001 (2017)
Influence of Annealing Technology on Spectral Properties of SiCx Thin Films Containing Silicon Quantum Dots
Zhao Fei, Yang Wen, Chen Xiaobo, and Yang Peizhi
In this paper, the silicon-rich SiCx thin films with silicon quantum dots are prepared at different annealing temperatures by magnetron co-sputtering, microwave annealing and rapid thermal annealing. The thin films are characterized by grazing-incidence X-ray diffraction (GIXRD), Raman spectrum, and photoluminescence (In this paper, the silicon-rich SiCx thin films with silicon quantum dots are prepared at different annealing temperatures by magnetron co-sputtering, microwave annealing and rapid thermal annealing. The thin films are characterized by grazing-incidence X-ray diffraction (GIXRD), Raman spectrum, and photoluminescence (PL) spectra technology. Influences of annealing technologies on the number and the size of silicon quantum dots, crystallization rate, and photoluminescence peak are discussed. The results show that compared to the rapid thermal annealing process, microwave annealing can not only lower the formation temperature of silicon quantum dots (200 ℃), but also reduce the β-SiC quantum dots formation temperature (100 ℃). At the same annealing temperature, the number, crystallization rate and photoluminescence peak intensity of the silicon quantum dots prepared by microwave annealing are much higher than that of the rapid thermal annealing. The number of the silicon quantum dots is the most, the silicon quantum dots size is the biggest (5.26 nm), the crystallization rate is the highest (74.25%), and the photoluminescence peak is the strongest when the temperature of microwave annealing reaches 1000 ℃. The results show that high-quality silicon quantum dots can be precipitated by microwave annealing..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 1, 131002 (2017)
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