Contents
2016
Volume: 36 Issue 6
42 Article(s)
Export citation format
Atmospheric Optics and Oceanic Optics
Statistical Distribution of PM2.5 Mass Concentration Profiles at West Suburb of Hefei City in 2014
Tao Zongming, Ma Xiaomin, Liu Dong, Xie Chenbo, Shan Huihui, Zhao Sugui, Zhang Hui, Zhang Qingze, and Wang Yingjian
Retrieving the profile of PM2.5 (particulate matter less than 2.5 μm in diameter) mass concentration can not only estimate column mass concentration of pollutants, but also follow pollutants diffusion rule in space, so as to provide scientific support for the prevention and control of atmospheric pollution. Suppose thaRetrieving the profile of PM2.5 (particulate matter less than 2.5 μm in diameter) mass concentration can not only estimate column mass concentration of pollutants, but also follow pollutants diffusion rule in space, so as to provide scientific support for the prevention and control of atmospheric pollution. Suppose that the type and component of aerosol remain unchanged in the period of one PM2.5 mass concentration detection in the boundary layer, by using the proportional relation between the aerosol extinction coefficient and PM2.5 mass concentration at ground, the profile of PM2.5 mass concentration can be obtained from the profile of aerosol extinction coefficient which is retrieved by the lidar system. Two cases of PM2.5 mass concentration and the characteristic change with altitude and time are analyzed, and the 82 nights data measured from March 2014 to February 2105 are averaged by season. The average profile of seasonal PM2.5 mass concentration profile is calculated..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 601001 (2016)
Pupil Calibration Method of Non-Modulation Pyramid Wavefront Sensor
Yan Zhaojun, Yang Pengqian, and Chen Xinyang
Pyramid wavefront sensor (PWFS) has the advantages of high spatial resolution and light utility efficiency. To correctly extract slope information of the wavefront from the pupil images of PWFS, the dimension and position of the pupils should be calibrated in advance. The effects of the dimension and position calibratiPyramid wavefront sensor (PWFS) has the advantages of high spatial resolution and light utility efficiency. To correctly extract slope information of the wavefront from the pupil images of PWFS, the dimension and position of the pupils should be calibrated in advance. The effects of the dimension and position calibration errors of the pupils on close-loop performance of adaptive optics system are investigated. The pupil calibration method of non-modulation pyramid wavefront sensor is proposed, and this method is verified by many times of simulated experiments under the conditions that system aberration and detection noise are considered. The simulation results show that the proposed method can calibrate the pupils accurately in the face of system aberration (its root mean square value is below 1.7λ). The method can be applied to the practical adaptive optics systems..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 601002 (2016)
Remote Sensing Aerosol Extinction Hygroscopic Growth Factor and Its Wavelength Dependence Using Lidar
Bo Guangyu, Li Aiyue, and Xu Chidong
A new method of using two-wavelength Mie-depolarization lidar for remote sensing extinction hygroscopic growth factor of aerosol near ground layer under varying conditions of relative humidity(RH) is proposed. Based on the algorithm used in lidar vertical aerosol hygroscopic growth observations, lidar horizontal measurA new method of using two-wavelength Mie-depolarization lidar for remote sensing extinction hygroscopic growth factor of aerosol near ground layer under varying conditions of relative humidity(RH) is proposed. Based on the algorithm used in lidar vertical aerosol hygroscopic growth observations, lidar horizontal measurements data is researched using strong correlation between extinction coefficient and RH, and the measured particle mass concentration going along with the decrease of depolarization ratio is used as a criterion, which proves that the hygroscopic effect of aerosol is the main cause of the extinction coefficient increment. Compared to the lidar vertical aerosol hygroscopic growth observations method, the proposed method has the advantage of the raising data selection criterion and simple meteorological conditions. Extinction hygroscopic growth factor can be calculated using valid data in lidar database, and its wavelength dependence is analyzed. Observation results at Hefei district show that, in various natural atmospheric environments, unimodal, bimodal and even multimodal aerosol distributions may exist. As a result, positive correlation, negative correlation and irrelevance between RH and Angstrom exponent can be observed, and hygroscopic growth factor at short wavelength can be weaker than, stronger than or equal with that at long wavelength..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 601003 (2016)
Remote Sensing Algorithm for Detecting Green Tide in China Coastal Waters Based on GF1-WFV and HJ-CCD Data
Zhang Hailong, Sun Deyong, Li Junsheng, Qiu Zhongfeng, Wang Shengqiang, and He Yijun
A large area outbreak of green tide poses serious negative impact on marine environment, fishery economy, and coastal tourism. Remote sensing technology has an advantage in macroscopic and dynamic monitoring of green tide in time, and is of significance for green tide treatment and prevention in time to reduce economicA large area outbreak of green tide poses serious negative impact on marine environment, fishery economy, and coastal tourism. Remote sensing technology has an advantage in macroscopic and dynamic monitoring of green tide in time, and is of significance for green tide treatment and prevention in time to reduce economic lost. We extract spectral reflectance characteristics of green tide from remote sensing data in coastal waters, and analyze spectral differences between green tide and normal waters. Towards the domestic satellite data of HJ-1 and GF-1, we develop a multispectral green tide index(MGTI)-multiband difference coupling algorithm that can be used to effectively detect green tide based on remote sensing technology. Meanwhile, remote sensing monitoring of green tide area by using Landsat7-ETM+ data is collected as reference, and also two conventional remote sensing algorithms, including normalized difference vegetation index(NDVI) and enhanced vegetation index(EVI), can be used for comparing with our developed algorithm. The obtained results demonstrate that the developed algorithm can be effectively applied into green tide monitoring in China coastal waters, and the monitoring accuracy is approximately 94%. This research can provide a theoretical basis and strategy for using domestic satellite data to monitor green tide in coastal waters..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 601004 (2016)
Analysis on Impact of Atmospheric Refraction on Radiative Transfer Process at Visible and Infrared Band
Hu Shuai, Gao Taichang, Li Hao, Cheng Tianji, Liu Lei, Zhang Ting, Huang Wei, Jiang Shiyang, and Dai Zhonghua
In order to quantitatively discuss the influence of atmospheric refraction on radiative transfer process, a vector radiative transfer model (VSPART) is established and the atmospheric refraction impact on diffuse light’s Stokes vectors and radiative flux density is discussed. In this model, the atmospheric refraction pIn order to quantitatively discuss the influence of atmospheric refraction on radiative transfer process, a vector radiative transfer model (VSPART) is established and the atmospheric refraction impact on diffuse light’s Stokes vectors and radiative flux density is discussed. In this model, the atmospheric refraction parametric process is simulated by using the ray-tracing method, and the radiative transfer equation is solved by using the matrix algorithm. The simulated results of VSPART agrees with literature results and classical radiative models such as SPDISORT(spherical discrete ordinate method), DISORT(discrete ordinate method), RT3/PolRadtran and MYSTIC (Monte Carlo code for the physically correct tracing of photons in cloudy atmospheres). The impact of atmospheric refraction on the Stokes vectors of down-welling diffuse light at surface (DLS) and up-welling diffuse light at the top of atmosphere (ULT) is analyzed for Rayleigh scattering atmosphere and atmosphere with aerosol. Besides, the variation of the atmospheric refraction effect with the solar zenith angle is analyzed as well. Simulation results show that the relative deviations of the diffuse light’s I, Q and U components due to refraction achieve 9.2%, 10.2% and 11.3%, and the relative deviation of radiant flux density approaches 5.3% when the solar zenith angle is 86° in the Rayleigh scattering atmosphere. For DLS, the impact of refraction is enhanced with the increasing of observing zenith angle, while for ULT, the fact is opposite. On the whole, the influence of atmospheric refraction on DLS is stronger than that on ULT. With the increase of aerosol optical thickness, the atmospheric refraction effect is gradually enhanced, and the influence of the atmospheric refraction for soot aerosol is much stronger than that for mineral dust and sea salt. When the solar zenith angle is larger than 70°, the impact of atmospheric refraction increases rapidly, and it is necessary to consider the atmospheric refraction process when simulating the radiative transfer..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 601005 (2016)
Diffraction and Gratings
Optical Absorption Properties of Quasi-Periodic Microstructures Arranged by Fibonacci Sequence
Dong Zedong, and Liu Youwen
A new kind of quasi-periodic optical microstructure arranged by the Fibonacci sequence is proposed. In the case of TM polarization, the absorptivity of the optical microstructure is calculated numerically based on the rigorous coupled wave analysis (RCWA) method. A parametric study is carried out to evaluate the influeA new kind of quasi-periodic optical microstructure arranged by the Fibonacci sequence is proposed. In the case of TM polarization, the absorptivity of the optical microstructure is calculated numerically based on the rigorous coupled wave analysis (RCWA) method. A parametric study is carried out to evaluate the influences of Fibonacci series duty ratio and the thickness of the coating film on microstructure. Under AM1.5 solar spectral irradiance, when the Fibonacci series is S3, the duty ratio is f=0.7, and the thickness of the coating film is t=20 nm, the maximum averaged absorptivity can reach 95.17% within the wavelength of 300~1100 nm, which suggests that it has great potential to be an anti-reflection layer on the surface of solar cells..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 605001 (2016)
Integrated Design to Complement Aberrations of Spherical Focusing Mirrors and Concave Holographic Gratings in Spectrometers
Zhao Xulong, Bayanheshig, Li Wenhao, Jiang Yanxiu, and Yang Shuo
A design method integrating the aberration-corrected concave holographic grating and focusing mirror has been proposed, and the effect of the aberration of the optical source focusing mirror on the resolution and signal to noise ratio of the spectrometer is considered. A physical model of aberration analysis including A design method integrating the aberration-corrected concave holographic grating and focusing mirror has been proposed, and the effect of the aberration of the optical source focusing mirror on the resolution and signal to noise ratio of the spectrometer is considered. A physical model of aberration analysis including a focusing mirror and a concave holographic grating has been built, an aberration coefficient expression is derived, a corrected aberration objective function is constructed, and an optimized design is finally obtained. In the integrated design, aiming at the monochromator grating in which the arm length is 170.3 mm and the curvature radius of the basement is 170.2 mm, the off-axis aberration caused by the focusing mirror is compensated through reversely increasing the holographic grating astigmatism. Compared with that of the traditional design, the root mean square size of image spot diagram decreases from 86 μm to 81 μm in the meridional direction, and from 765 μm to 167 μm in the sagittal direction. This method improves the capability of correcting system aberration and provides new design concepts for the optical system of concave grating spectrometers..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 605002 (2016)
Fiber Optics and Optical Communications
Etched Diffraction Grating Wavelength Router with Uniform-Loss and Flat-Passband
Mu Ge, and He Jianjun
An etched diffraction grating wavelength router (EDGR) with arc-shaped grating teeth is proposed,and the loss uniformity and spectral passband of the device can be improved simultaneously with proper design for the shape of the grating teeth. A 4×4 EDGR with 400 GHz channel spacing, centered at 1550 nm and based oAn etched diffraction grating wavelength router (EDGR) with arc-shaped grating teeth is proposed,and the loss uniformity and spectral passband of the device can be improved simultaneously with proper design for the shape of the grating teeth. A 4×4 EDGR with 400 GHz channel spacing, centered at 1550 nm and based on InP platform is designed. Simulation results show that the loss difference of all channels is reduced from 8.1 dB to 0.8 dB. The shape of the spectral response is flat-top and the 1 dB bandwidth is increased from 0.3 nm to 1.6 nm. By adjusting the design parameters, the loss uniformity, bandwidth and entire loss of the device can be balanced. Experimental results show that the loss difference of all channels is 3.1 dB and 1 dB bandwidth is 1.1 nm. The crosstalk of the device is better than -12 dB. The validity of this method is verified. This method does not need to increase the chip size or add extra elements, which can be applied to etched diffraction gratings in any material platform..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 606001 (2016)
Fourier Optics and Signal Processing
Information Encryption Technology Based on Digital Watermarking and Iteration Algorithm
Xie Qingkun, Jiang Yanru, Zhang Wenfei, Wang Jing, and Qu Enshi
The digital watermarking technology is a new information encryption technology. It has a good capacity in camouflage. However, it is limited by the phase detection errors, and the traditional retrieval algorithms are unpractical by means of calculating phase first and then deducing the original images in the process ofThe digital watermarking technology is a new information encryption technology. It has a good capacity in camouflage. However, it is limited by the phase detection errors, and the traditional retrieval algorithms are unpractical by means of calculating phase first and then deducing the original images in the process of restoring signal. The iteration algorithm can efficiently reconstruct these weak signals by applying some constrains in frequency domain and spatial domain. A new technology of information encryption and reconstruction is proposed combining with the theory of digital watermarking and iteration algorithm. This technology can overcome the limitation of phase detection errors. Furthermore, it can effectively hide and recover the embedded information, and the information can hardly be deciphered, which depends on the accuracy of phase information. Theoretical analysis and simulation results demonstrate that mean square error of the proposed algorithm can accomplish convergence by only several iterations within few seconds, which shows high robustness. It has a good performance in camouflage and fast-convergence, and could be widely applied in personal identity camouflage and information identity..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 607001 (2016)
Geometric Optics
Echo Characteristics Model of Cat-Eye Effect Based on Matrix Optics
Wu Dongsheng, Liu Bingqi, Hu Wengang, Liu Jie, and Ying jiaju
The active laser detection based on cat-eye effect is used as the application background, according to the defect of usual analytical method to research the cat-eye effect echo characteristics. The analytical method of optical window mapping is proposed to analyze beam transformation via matrix optics, and the model ofThe active laser detection based on cat-eye effect is used as the application background, according to the defect of usual analytical method to research the cat-eye effect echo characteristics. The analytical method of optical window mapping is proposed to analyze beam transformation via matrix optics, and the model of echo shape and energy is built on the condition that the reflecting element is defocused and the incident beam is not normal incidence. It resolves the problem that the physical significance of echo divergence angle is wrong and the echo spatial dimension cannot be figured out. The theoretical model is certificated by experiment through setting the ideal cat-eye optical system. The calculation results are in good agreement with the experimental results. The proposed model and related results are very important to develop active laser detection and anti-detection technology based on cat-eye effect..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 608001 (2016)
Imaging Systems
A Single-Pixel Imaging System with a Target in the Middle of Double Scattering Medium
Han Jianhui, Tian Yongzhi, Fan Xiaohang, Xin Haoyi, Hu Yangming, Liu Xiaomin, Zang Huaping, and Liang Erjun
On the basis of the analysis of scattering media scattering characteristics, a single pixel imaging method is proposed to capture the image of the objects in scattering media. Based on the digital micro mirror array and a single point detector, the corresponding single-pixel imaging system is designed and built. SeriesOn the basis of the analysis of scattering media scattering characteristics, a single pixel imaging method is proposed to capture the image of the objects in scattering media. Based on the digital micro mirror array and a single point detector, the corresponding single-pixel imaging system is designed and built. Series of stripe patterns with different phases are loaded on the digital micro mirror array and the intensity informations are recorded by the detector. Then the image restoration algorithm is used to get the reconstructed image of the objects in the scattering media. In order to remove the noise, the source of noise is analyzed, a filter is designed for filtering, and the image quality is significantly improved. Compared with the traditional scattering medium imaging systems, this system is simple and without complex calibration process, so it can apply to many fields..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 611001 (2016)
Remote Sensing Image Reconstruction Method Based on Non-Local Similarity and Low Rank Matrix
Huang Zhijuan, Tang Chaoying, Chen Yueting, Li Qi, Xu Zhihai, and Feng Huajun
A compressed sensing reconstruction method based on nonlocal similarity, low rank matrix and minimum total variation (TV) is proposed, considering the non-local similarity of remote sensing images. It fully exploits the nonlocal similarity prior, local smoothness prior of remote sensing images and the low rank propertiA compressed sensing reconstruction method based on nonlocal similarity, low rank matrix and minimum total variation (TV) is proposed, considering the non-local similarity of remote sensing images. It fully exploits the nonlocal similarity prior, local smoothness prior of remote sensing images and the low rank properties of matrix. A new joint block matching method based on Euclidean distance and structural similarity is developed, which makes the matching result more accurate. The reconstruction of high quality remote sensing image is realized finally. Simulation results confirm that the proposed algorithm can achieve high reconstruction quality comparing with the traditional reconstruction method based on sparse transform domain or TV regularization. The peak signal to noise ratio and structural similarity have a great improvement，and the effectiveness of the proposed method is verified..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 611002 (2016)
Application of Variational Bayesian Deconvolution Method in Laser Reflective Tomography Imaging
Gu Yu, Hu Yihua, Hao Shiqi, Wang Jincheng, and Wang Di
Range-resolving laser reflective tomography imaging is a new type of laser imaging system which takes both long-range and high-resolution imaging characteristics into account. When the pulse width of laser emission is larger than the sampling period, the received echo is regarded as the convolution of reflectance distrRange-resolving laser reflective tomography imaging is a new type of laser imaging system which takes both long-range and high-resolution imaging characteristics into account. When the pulse width of laser emission is larger than the sampling period, the received echo is regarded as the convolution of reflectance distribution and emission pulses. Imaging resolution can be reduced when the target reflectance distribution profile is reconstructed. Non-blind deconvolution of one-dimensional detected echo signal is carried out with variational Bayesian method. Pulse compression of the detected echo signal is done, and the issue of image degradation caused by the convolution effect is solved effectively. The laser reflective tomography experiment is designed and the measured data are processed. Reconstructed images show that the proposed method can effectively improve image resolution of the system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 611003 (2016)
Terahertz Joint Analyzer with Imaging and Spetrum Detection
Yang Minwei, Ji Haibing, Tan Zhiyong, Zhang Huifang, Wang Qiu, Peng Ningsong, Gu Jianqiang, Zhu Yiming, and Cao Juncheng
A terahertz quantum cascade laser, which is made in-house, has excellent device performance and is easy for integration and application. Terahertz wave emitted from the laser device can penetrate non-metal materials with little loss. A transmission imaging system with certain spatial dimension and resolution is built wA terahertz quantum cascade laser, which is made in-house, has excellent device performance and is easy for integration and application. Terahertz wave emitted from the laser device can penetrate non-metal materials with little loss. A transmission imaging system with certain spatial dimension and resolution is built with the terahertz quantum cascade laser together with peripheral supporting optics and an array receiving module. Key parameters in the beam shaping are studied. A terahertz joint analyzer is developed by using the imaging system together with an all fiber terahertz time domain spectrum system based on photoconductive antenna. The terahertz joint analyzer can detect both terahertz imaging and fingerprints of objects hidden in non-metal packaging. The operation software of the whole instrument can control and monitor all the devices inside. The terahertz joint analyzer system offers a method of fast, intuitive and accurate location and non-destructive analysis for the detecting objects..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 611004 (2016)
Instrumentation, Measurement and Metrology
Lens Surface Distance Measurement with Large Range and High Precision Based on Low Coherence Interferometry
Shi Zhonghua, Yang Baoxi, Hu Xiaobang, Jin Chaoqun, Wei Zhangfan, Li Jing, and Huang Huijie
The distance measurement of optical mirror surfaces based on low coherence interferometry is described. The system realizes lens surface distance measurement with high precision, by first using double micro-electromechanical systems (MEMS) switches to multiply enlarge the measuring range, secondly by using co-light-patThe distance measurement of optical mirror surfaces based on low coherence interferometry is described. The system realizes lens surface distance measurement with high precision, by first using double micro-electromechanical systems (MEMS) switches to multiply enlarge the measuring range, secondly by using co-light-path laser ranging structure to realize the displacement measurement of the scanning mirror, and thirdly by using the envelope extraction algorithm to obtain the zero light path difference location of low coherence light interference signal. The whole measurement system has an all-fiber structure. Lens surface distances of Invar gauge, optical system with large air gap and optical lens group are measured with this system. Under the condition of the scanning range of 300 mm, distance measurement within the range of 0.02~550 mm by using MEMS switches is realized, and the experimental results indicate that the system possesses high measurement accuracy below 0.5 μm.Such a measurement system has important applications in optical testing and optical alignment of high precision optical systems, such as lithography exposure system, aerial camera, and laser resonator..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 612001 (2016)
A Method of Both Height Mapping and Camera Calibration at the Same Time in Modulation Measuring Profilometry
Lu Mingteng, Su Xianyu, Cao Yiping, You Zhisheng, and Jing Hailong
In the calibration process for traditional modulation measuring profilometry, a standard plane needs to be moved several times to establish the mapping relationship between modulation and actual physical height. And the camera calibration process needs to be done separately. A new calibration method for modulation measIn the calibration process for traditional modulation measuring profilometry, a standard plane needs to be moved several times to establish the mapping relationship between modulation and actual physical height. And the camera calibration process needs to be done separately. A new calibration method for modulation measuring profilometry is proposed, which can implement height mapping and camera calibration at the same time. In this method, a standard block is used instead of the standard plane and the complex translation stage system in the traditional methods. Several separated stages with the same height but whose spatial distribution is discrete are used to form a virtual calibration plane, on which the modulation distribution is obtained by fitting process, and the multi-stages can also be used in the lateral coordinates calibration process. The characteristics of this method are that only one scanning process is required for setting up the mapping relationship between the modulation and height and calibrating the lateral coordinates. The theory analysis of the proposed method is given and experiment proves the feasibility of the method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 612002 (2016)
A Fast Phase Extraction Algorithm with One-Step π Phase-Shifting
Zhu Ronggang, Zhu Rihong, and He Yong
The one-step π phase-shifting phase extraction algorithm is presented to achieve dynamic measurement. Two interferograms with π phase-shifting are rearranged to form a spatial-temporal fringe containing time domain and space domain information. This algorithm can solve phase fast by extracting spatial-temporal pattern The one-step π phase-shifting phase extraction algorithm is presented to achieve dynamic measurement. Two interferograms with π phase-shifting are rearranged to form a spatial-temporal fringe containing time domain and space domain information. This algorithm can solve phase fast by extracting spatial-temporal pattern signal. In frequency spectrum of spatial-temporal fringe pattern, time frequency is introduced in this method, signal spectrum of spatial-temporal pattern is effectively separated from the background interference spectrum, and the signal spectrum can be extracted effectively without high carry frequency. The proposed algorithm is applied in phase-shifting interferometry. Comparing with the traditional phase shifting method, this method can eliminate phase-shifting error and high-frequency noise in test result effectively. In addition, the influence of different frequencies and phase-shifting errors on measurement accuracy is analyzed. The measurement error root mean square of the reconstruction surface can be controlled in 1.358×10-3λ when the normalized spatial frequency is more than 0.03 and phase-shifting error changes within ±30°..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 612003 (2016)
A New Method for Deformation Phase Measurement by Speckle Correlation Theory
Zhao Ran, and Sun Ping
A novel algorithm is proposed to extracts the out-of-plane component of deformation-phase from two continuous fringe patterns. The velocity field between two consecutive frames is estimated by digital speckle correlation method (DSCM). According to the optical flow constrained equation, the whole-field deformation-phasA novel algorithm is proposed to extracts the out-of-plane component of deformation-phase from two continuous fringe patterns. The velocity field between two consecutive frames is estimated by digital speckle correlation method (DSCM). According to the optical flow constrained equation, the whole-field deformation-phase map is obtained by the estimations of the velocity field and the fringe frequency of the original image. The principle of measuring deformation-phase method is introduced based on DSCM. The experiment and computer simulation are done on the deformation-phase measurement of disk center loading and fixed around. The effectiveness of this method is verified. Simulation and experimental results show that the proposed method can connect the visible in-plane velocity field and the extraction of out-of-plane deformation-phase and demodulate the out-of-plane component of deformation-phase from the whole-field. The proposed method has advantages in the operation process as easy and convenient, and it neither need conversion of fringe image to frequency domain, also do not need phase envelope operation. The deformation-phase information extracted from denser fringe place is more accuracy. The proposed algorithm provides a new approach for whole-field deformation-phase measurement and dynamic object deformation measurement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 612004 (2016)
Pixel Matching Method in On-Line Three-Dimensional Measurement Based on Phase Prediction
Xu Xingfen, Cao Yiping, and Peng Kuang
Pixel matching must be done because the coordinates of the object in different captured patterns are not one-to-one corresponding caused by the movement of object. A pixel matching method in on-line three-dimensional measurement based on phase prediction is proposed. Only one fixed sinusoidal fringe is needed to projecPixel matching must be done because the coordinates of the object in different captured patterns are not one-to-one corresponding caused by the movement of object. A pixel matching method in on-line three-dimensional measurement based on phase prediction is proposed. Only one fixed sinusoidal fringe is needed to project on a measured object moving on the pipeline. While the object is coming to some positions with a certain adjacent displacement, the deformed patterns modulated by the object are captured synchronously with CCD camera. Dealing the captured deformed patterns with Fourier transform profilometry (FTP) method, the phase information of the object in those positions can be predicted to assist the pixel matching, which realizes the one-to-one corresponding of the object, and extracts the equivalent phase-shifting deformed patterns. So the 3D surface shape of the object moving on the pipeline can be reconstructed successfully with an equal phase-shifting algorithm. The results of simulation and experiment verified its feasibility and validity. Meanwhile, compared with the on-line FTP method, the root mean square error derived by the on-line FTP and the proposed method are 1.013 mm and 0.024 mm respectively, which shows the proposed method has higher precision in on-line three-dimensional measurement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 612005 (2016)
Integrated Optics
Fabrication and Performance Evaluation of Polymer Waveguides for Optical Printed Circuit Board Applications
Xu Xiao, Ma Lin, Zhang Wenjia, Du Jiangbing, and He Zuyuan
Polymer optical waveguides are fabricated on FR-4 substrates with UV-curable epoxy resins by the lithography method. The experiment results show that the typical loss and the crosstalk of the waveguides are less than 0.05 dB/cm and -60 dB, respectively. Moreover, the waveguides exhibit good misalignment tolerance. WhenPolymer optical waveguides are fabricated on FR-4 substrates with UV-curable epoxy resins by the lithography method. The experiment results show that the typical loss and the crosstalk of the waveguides are less than 0.05 dB/cm and -60 dB, respectively. Moreover, the waveguides exhibit good misalignment tolerance. When there is a misalignment of ±5 μm at the input end, the increased insertion loss is less than 0.2 dB. A simulation model based on beam propagation method is used to investigate the mode power distribution, differential mode delay, and dependence of coupling efficiency on the launching conditions. The results indicate that using a fiber with core diameter comparable with the size of the waveguide excites fewer higher order modes and largely improves the waveguide performance. The fabricated optical polymer waveguides are promising as key devices for optical printed circuit board applications..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 613001 (2016)
Lasers and Laser Optics
Astronomical Laser Frequency Comb for High Resolution Spectrograph of a 2.16-m Telescope
Wu Yuanjie, Ye Huiqi, Han Jian, Zou Pu, Fu Lingtong, and Xiao Dong
An astronomical laser frequency comb (astro-comb), which will be applied as a calibrator on the high resolution spectrograph of the 2.16-m telescope in Xinglong Observatory, is introduced. The astro-comb is based on an ytterbium-doped fiber laser frequency comb. By mode filtering, the mode spacing of the comb is increaAn astronomical laser frequency comb (astro-comb), which will be applied as a calibrator on the high resolution spectrograph of the 2.16-m telescope in Xinglong Observatory, is introduced. The astro-comb is based on an ytterbium-doped fiber laser frequency comb. By mode filtering, the mode spacing of the comb is increased to 25 GHz, which matches the resolution of the astronomical spectrograph. After spectral broadening and flattening, the spectrum span increases to more than 270 nm in visible range, the spectrum flatness maintains within 1 dB for a long time, and the side mode suppression ratio reaches 42 dB. The theoretical calibration precision of the radial velocity for the astro-comb reaches cm/s level, which meets the requirements for searching the earth-like extrasolar planets and directly detecting the acceleration of the cosmic expansion..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 614001 (2016)
Local Maximum Algorithm for Detecting Spectral Peaks of Semiconductor Lasers
Hou Xibao, Liu Jiaqing, Zhang Zhihui, and Han Shunli
A self-adaptive local maximum algorithm for detecting spectral peaks of semiconductor lasers is proposed by analyzing actually measured spectrum characteristics of Fabry-Perot laser diode (FP-LD) and distributed feedback laser diode (DFB-LD), and the algorithm can be used to detect the spectra of laser diodes. In the aA self-adaptive local maximum algorithm for detecting spectral peaks of semiconductor lasers is proposed by analyzing actually measured spectrum characteristics of Fabry-Perot laser diode (FP-LD) and distributed feedback laser diode (DFB-LD), and the algorithm can be used to detect the spectra of laser diodes. In the algorithm, a local maximum matrix of data series is established and is modified with its row vector characteristics, and the peak is located with its column vector characteristics that are further amended and compensated. The algorithm is free from manual operation during the whole searching process, has higher noise-resistance, self-adaptability and robustness, and meets the requirements of real-time computation. Compared with the comparison algorithm, optimized derivative algorithm and genetic algorithm, the local maximum algorithm has obvious advantages in terms of accuracy rate and computation time. The average test accuracy rate reaches 98% while the average computation time is only 0.12 s. The algorithm can be applied to real-time analysis of actually measured spectrum characteristics of semiconductor lasers..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 614002 (2016)
High Power Sub-Picosecond Ultraviolet Calibration Facility and Its Preliminary Application
Deng Keli, Chen Tao, Wang Qiangqiang, and Cao Zhurong
A sub-picosecond ultraviolet calibration facility is established based on the uniform profile of a gas dye laser, and this is specially designed for the inertial confinement fusion diagnosis system calibration. The laser beam operates at 248.5 nm with a pulse width of about 0.5 ps and a total energy of about 100 mJ, anA sub-picosecond ultraviolet calibration facility is established based on the uniform profile of a gas dye laser, and this is specially designed for the inertial confinement fusion diagnosis system calibration. The laser beam operates at 248.5 nm with a pulse width of about 0.5 ps and a total energy of about 100 mJ, and generates a uniform spot that is about 35 mm×25 mm. Some preliminary calibration results of a high temporal resolution diagnosis system are obtained on the facility, which proves that the parameters of picosecond systems can be calibrated on the facility. Since the energy output is stable, it is possible to develop a quantitative time-resolving calibration technique..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 614004 (2016)
Impact of Optical Parametric Fluorescence on Temporal Contrast for Various Pump Profiles
Wang Bopeng, Su Jingqin, Zeng Xiaoming, Zhou Kainan, Wang Xiaodong, Zuo Yanlei, Wang Xiao, Guo Yi, Zhu Qihua, and Jing Feng
The optical parametric chirped-pulse amplifier (OPCPA) is one of the widely utilized amplifiers to boost ultra-short and ultra-intense pulses. The optical parametric fluorescence is the intrinsic quantum noise of OPCPA and the formed pedestal can degrade the temporal contrast of the output signal pulses greatly. NumeriThe optical parametric chirped-pulse amplifier (OPCPA) is one of the widely utilized amplifiers to boost ultra-short and ultra-intense pulses. The optical parametric fluorescence is the intrinsic quantum noise of OPCPA and the formed pedestal can degrade the temporal contrast of the output signal pulses greatly. Numerical simulation is adopted to study the evolution of the parametric fluorescence and its impact on the temporal contrast under various signal-to-pump duration ratios and various pump profiles. The results indicate that when the gain is fixed, the temporal contrast and the product of conversion efficiency and bandwidth increase firstly and then decrease with the increasing duration ratio. There is an optimal ratio to maximize the temporal contrast and the product simultaneously. When the ratio is lower than the optimal value, the temporal contrast decreases and the product increases with the increasing order of super-Gaussian pump profiles. The temporal contrast increases and the product decreases with the increasing order when the duration ratio is higher than the optimum..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 614005 (2016)
Machine Vision
Moving Object Detection Algorithm Based on Improved Visual Background Extractor
Mo Shaowen, Deng Xinpu, Wang Shuai, Jiang Dan, and Zhu Zhoupeng
Aiming at the problems of ghost, background turbulence in high frequency, camera jitter and error of background update caused by spatial propagation technique in classic visual background extractor（ViBe） algorithm, an improved ViBe algorithm is proposed. Combined with visual saliency, the new method determines whether Aiming at the problems of ghost, background turbulence in high frequency, camera jitter and error of background update caused by spatial propagation technique in classic visual background extractor（ViBe） algorithm, an improved ViBe algorithm is proposed. Combined with visual saliency, the new method determines whether the ghost target exists in the background model or not, and adaptively changes the time subsampling factor through the level of ghost for each pixel in the background model, which can improve the rate of ghost elimination. Self-adaptive threshold is adopted in the process of model matching by establishing a blinking degree matrix to judge the high-frequency disturbance level of background, so that the background model is better suitable for the dynamic background. Small object discard and hole filling strategies are added to the new method. It can judge if a foreground pixel is a noise point caused by camera jitter or an error of background update by counting pixel numbers in 24-connected neighboring region of foreground pixels. Therefore, it can improve the robustness of the algorithm. Experiments demonstrate that the improved algorithm is a good way to make up for the deficiency of the original ViBe algorithm. The accuracy and recognition rate are improved greatly..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 615001 (2016)
Structure Design of Single Camera Omnidirectional Stereo Vision Sensor
Song Ya, Chai Xinghua, and Zhou Fuqiang
Conventional wide-field three-dimensional (3D) measurement is usually implemented by measuring system consisting of multiple sensors. Difficulties, including sensor synchronization and unified measuring coordinate system of multiple sensors, lead to the incompatibility between high accuracy and high speed. An omnidirecConventional wide-field three-dimensional (3D) measurement is usually implemented by measuring system consisting of multiple sensors. Difficulties, including sensor synchronization and unified measuring coordinate system of multiple sensors, lead to the incompatibility between high accuracy and high speed. An omnidirectional stereo vision sensor consisting of a single camera and two rectangular pyramid mirrors is designed to realize real-time 3D measurement of objects in wider field. The rectangular pyramid mirrors are symmetrically placed, with their top opposite to each other, and a high resolution industrial camera is set at the head of the under rectangular pyramid. The rectangular pyramid mirrors are reflecting and imaging as four pairs of virtual cameras. It is equivalent to the traditional binocular vision sensor in which the counterpart points are obtained by two cameras. Thus synchronization measurement in horizontal four direction is realized by four pairs of virtual cameras. Some disadvantages of traditional binocular vision sensor are overcame, such as big size，narrow field of view, asynchronous image collection etc. Moreover, constant perspective projection of images is ensured and distortion in images reflected by curved mirror is avoided, which makes the later work much easier..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 615002 (2016)
Materials
Optical True Time-Delay lines of Photonic Crystal Slow Light Waveguides Used in Phased Array Radar
Cui Naidi, Kou Jieting, Zhao Heng, Cao Guowei, Wang Wanjun, Guo Jin, and Feng Junbo
The photonizing research is the development trend of phased array radar. Due to its excellent characteristics on the integration level and optical properties, the photonic crystals have extensive application prospect in the photonics research of optical true time-delay lines phased array radar. Based on the slow light The photonizing research is the development trend of phased array radar. Due to its excellent characteristics on the integration level and optical properties, the photonic crystals have extensive application prospect in the photonics research of optical true time-delay lines phased array radar. Based on the slow light characteristics and thermo-optical modulation theory, optical true time-delay lines applied in beam forming network of phased array radar are proposed. By optimizing parameters of the photonic crystal slow waveguide, high accurate modulation of of photonic crystal designed ranging from 0 ps/mm to 36.69 ps/mm is achieved. Meanwhile, the delay bandwidth larger than 23 GHz is realized. By optimizing variation characteristics of the group velocity with temperature, the time delay variation is in the range from 0.36 ps/mm to 1.57 ps/mm whenever the temperature changes 1 ℃. The optical true time-delay lines based on photonic crystal proposed can achieve highly efficient and accurate modulation on the delay. Compared with the traditional electrical domain beam-forming network, it has the advantages of high integration, wide instantaneous bandwidth and high tuning accuracy, which can provide a theoretical basis for the beam-forming network research of the high frequency wideband phased array radar..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 616001 (2016)
Study on Mid-Infrared Spectral Properties of Ho3+/Yb3+ Co-Doped Fluorogermanate Glasses
Qian Guoquan, Tang Guowu, Qian Qi, and Chen Ganxin
Emission properties of mid-infrared at 2.0 μm and 2.85 μm, and visible up-conversion as well as energy transfer mechanism between two rare earth ions, Ho3+ and Yb3+, are studied in Ho3+/Yb3+ co-doped fluorogermanate glasses pumped by a 980 nm laser diode. Enhanced mid-infrared 2.0 μm and 2.85 μm emission is obtained inEmission properties of mid-infrared at 2.0 μm and 2.85 μm, and visible up-conversion as well as energy transfer mechanism between two rare earth ions, Ho3+ and Yb3+, are studied in Ho3+/Yb3+ co-doped fluorogermanate glasses pumped by a 980 nm laser diode. Enhanced mid-infrared 2.0 μm and 2.85 μm emission is obtained in fluorogermanate glass samples which is co-doped with 1% Ho2O3 and 9% Yb2O3(mole fractions). The measured decay lifetime of Ho3+ is 6.19 ms, and the theoretically calculated maximum emission cross section at 2023 nm is about 6.6×10-21 cm2. The results indicate that Ho3+/Yb3+ co-doped fluorogermanate glasses are suitable for mid-infrared 2.0 μm and 2.85 μm emission..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 616002 (2016)
Nonlinear Optics
Spatiotemporal Evolution of the Light Field Inside the Microresonator with Normal Dispersion
Xu Xin, Hu Xiaohong, Feng Ye, Liu Yuanshan, Wang Yishan, and Wei Ruyi
Based on the Lugiato-Lefever equation, the spatiotemporal evolutions in microresonator are discussed respectively, which is pumped by the continuous wave (CW) light as well as the combination of CW light and periodical pulse train simultaneously, and the effect of each parameter on light field is studied. Simulation reBased on the Lugiato-Lefever equation, the spatiotemporal evolutions in microresonator are discussed respectively, which is pumped by the continuous wave (CW) light as well as the combination of CW light and periodical pulse train simultaneously, and the effect of each parameter on light field is studied. Simulation results indicate that the dark soliton can exist in the microresonator with CW pumped. The width of the dark soliton pulse increases with the dispersion coefficient. The shape of the dark soliton pulse is varied when the frequency detuning is increased. Meanwhile, in the normal dispersion regime, the pulses can form in the microresonator by the use of synthetical pumping manner. The drawback is compensated that the bright soliton pulse is difficult to be generated in the microresonator for single CW pumped of certain parameters configuration. Moreover, the high amplitude of the pump pulses leads to the pulse split, the pulse stretching and the loss of the pulse occur when the frequency detuning of the microresonator rises. Theoretical analysis results are significant for high-quality Kerr optical frequency comb and their practical applications, and they are helpful for selecting the proper microresonator and pump parameters..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 619001 (2016)
Study on Transformation of Kuznetsov-Ma Soliton to Quasi-Fundamental Soliton Based on Spectral-Filtering Method
Yang Guangye, Li Lu, and Tian Jinping
Based on the Kuznetsov-Ma soliton solution of the nonlinear Schrdinger equation, the Kuznetsov-Ma soliton with zero background is investigated. The relation between the Kuznetsov-Ma soliton with zero background and the quasi-fundamental soliton is concluded. The dynamics of the Kuznetsov-Ma soliton to the quasi-fundamBased on the Kuznetsov-Ma soliton solution of the nonlinear Schrdinger equation, the Kuznetsov-Ma soliton with zero background is investigated. The relation between the Kuznetsov-Ma soliton with zero background and the quasi-fundamental soliton is concluded. The dynamics of the Kuznetsov-Ma soliton to the quasi-fundamental soliton in the single mode fiber by means of the spectral-filtering method is considered. The results show that the pulse with zero background extracted from the Kuznetsov-Ma soliton at the maximally compressed position can propagate stably in optical fiber in form of quasi-fundamental soliton. And the pulse tends to the form of the fundamental soliton with the increase of the physical behavior governing parameter. Through the analysis of stability, it is found that the quasi-fundamental soliton has a stable propagation velocity under small random perturbations applied to the initial condition..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 619002 (2016)
Optical Design and Fabrication
Optical Design of Broadband Advanced Wadsworth Grating Imaging Spectrometer
Yu Lei, Lin Guanyu, and Zhang Zihui
An advanced optical system has been obtained to solve the problem that the traditional Wadsworth optical system can not be applied for broadband imaging spectrometer with high resolution. The meridian and sagittal focal lengths have been changed by the method of adding a cylindrical lens into the Wadsworth optical systAn advanced optical system has been obtained to solve the problem that the traditional Wadsworth optical system can not be applied for broadband imaging spectrometer with high resolution. The meridian and sagittal focal lengths have been changed by the method of adding a cylindrical lens into the Wadsworth optical system. The optimal imaging conditions including location, inclined angle and wedge angle of the cylindrical lens have been calculated based on the analysis of the astigmatism and optical path. An example of the advanced optical system design with the working waveband of 400~800 nm has been presented to verify the theory. The results present good optical performances of the advanced system. The modulation transfer functions in all fields of view and working waveband are over 0.57, and the spectral resolution is 1.6 nm. The Wadsworth system is improved effectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 622001 (2016)
Influence of Three-Point-Mount-Induced Deformation for a Three-Mirror-Anastigmatic Telescope on Its Astigmatic Field
Zou Gangyi, Fan Xuewu, Pang Zhihai, Wang Chenchen, and Li Ruichang
In order to improve the efficiency of alignment for a three-mirror-anastigmatic (TMA) telescope with large aperture, the influence of three point mount induced (TPMI) deformation on its astigmatic field distribution in the aligning process is analyzed. Based on the vector aberration theory and aperture coordinate transIn order to improve the efficiency of alignment for a three-mirror-anastigmatic (TMA) telescope with large aperture, the influence of three point mount induced (TPMI) deformation on its astigmatic field distribution in the aligning process is analyzed. Based on the vector aberration theory and aperture coordinate transformation, the astigmatic field distribution characters for the aligned and misaligned TMA telescope are analyzed with TPMI deformation on mirrors located at or away from the aperture stop. Finally, the surface error due to TPMI deformation is simulated by the optical design software CODE V using Z10 and Z11, the terms of fringe Zernike polynomial. The characteristic field distribution of astigmatism is verified by the real-ray-tracing method. The results indicate that the astigmatic field distributions are not affected when the TPMI deformation is on the primary mirror (aperture stop), and it shows different characteristic field distributions when the TPMI deformation is on the secondary or tertiary mirror (not aperture stop) for the aligned or misaligned telescope because of producing astigmatism with the field conjugated and field linear. The aligning state of TMA telescope can be qualitatively analyzed by its astigmatic field distribution at the final aligning stage, which is quite instructive for the alignment of TMA telescopes with large aperture..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 622002 (2016)
Optical Devices
Theory and Precision Maintenance Method of On-Orbit Reflectance Calibration
Huang Wenxin, Zhang Liming, Si Xiaolong, Cao Xingjia, Zhu Xuemei, and Li Mengfan
The theory of on-orbit reflectance calibration of the solar diffuser panel is expounded and the physical model of on-orbit reflectance calibration is established. As the precision of on-orbit calibration is affected mostly by the degeneration of the solar diffuser’s bidirectional reflectance distribution function(BRDF)The theory of on-orbit reflectance calibration of the solar diffuser panel is expounded and the physical model of on-orbit reflectance calibration is established. As the precision of on-orbit calibration is affected mostly by the degeneration of the solar diffuser’s bidirectional reflectance distribution function(BRDF), the method of monitoring the degeneration of BRDF is discussed. According to the monitoring physical model of the solar diffuser stability monitor of the moderate resolution imaging spectroradiometer (MODIS) and the problem founded in the on-orbit performance evaluation, an optical structure of integrating sphere with two imports for light and a baffle inside is proposed. The parameters in its physical model are decreased and some factors that bring uncertainties are cut down while the function can be ensured. It is validated that the optical structure can prevent the sun view response from the ripple signal response in experiment. Based on the physical model of the new optical structure and the domestic testing level, the uncertainty of this system is estimated, and it can be less than 0.68%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 623001 (2016)
Development and Calibration of Dual-Waveband Infrared Radiometer for Jones Calibration Method
Zhang Zhao, Wan Zhi, Sun Jingxu, Liu Zexun, Ren Jianwei, and Ren Jianyue
At present, we typically use large extended radiation source as radiometric calibration device for the out-field work of large aperture dual-waveband infrared theodolite system. This method needs two sets of equipments, which exists the disadvantages of high power consume, inconvenient portable performance and difficulAt present, we typically use large extended radiation source as radiometric calibration device for the out-field work of large aperture dual-waveband infrared theodolite system. This method needs two sets of equipments, which exists the disadvantages of high power consume, inconvenient portable performance and difficult to develop. To solve this problem, the principles, processes and technical performances of different calibration methods are analyzed. Then the Jones method is selected as large aperture infrared theodolite out-field work environment radiometricca libration meth. The dual-band infrared radiometer is developed, which consists of two parts, blackbody lighting tube and reference radiometer. The radiometer uses Newton structure as telescopic system and relay optical path system, and selects InGaAs and PbSe as double-band infrared detectors to calibrate short wave infrared radiation (SWIR) and radiation middle wave infrared (MWIR) respectively. Then the necessity of the reference radiometer calibration to ensure the infrared theodolite final measuring precision is discussed, and different calibration methods and results for calibrating reference radiometer in SWIR and MWIR are presented. Finally, the calibration uncertainty of the radiometer is analyzed, the SWIR and MWIR calibration uncertainties are 4.12% and 2.35% respectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 623002 (2016)
Physical Optics
Reflection and Transmission on Charged Surface-Modified Fresnel Formulas
Zhang Zijia, Pan Qi, Chen Haixiu, Liu Qingqing, and Yan Fei
According to the general boundary conditions of the electromagnetic field, the reflection and transmission laws of electromagnetic waves on the charged interface of two different media are studied. It is proved that the reflection and the refraction laws for the charged interface are the same as that for the uncharged According to the general boundary conditions of the electromagnetic field, the reflection and transmission laws of electromagnetic waves on the charged interface of two different media are studied. It is proved that the reflection and the refraction laws for the charged interface are the same as that for the uncharged interface. The amplitude reflection coefficient and the amplitude transmission coefficient are derived for the reflection and transmission of the parallel and vertical components of the incident waves on the charged surface, i.e. modified Fresnel formulas. Due to the different interface conduction characteristics, surface charge distribution on the interface of two different media will affect the surface conductivity of the interface, and the modified Fresnel formulas are related to the surface conductivity and electromagnetic impedance of free space. The calculation results show that the amplitude reflection coefficient and the amplitude transmission coefficient as well as the reflectance and the transmittance will change when the surface conductivity varies with the surface charge density or the interface characteristics..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 626001 (2016)
Remote Sensing and Sensors
Experimental Demonstration of Spotlight Mode Synthetic Aperture Ladar
Wu Shudong, Huang Jianyu, Zhao Zhilong, Wang Kunpeng, Dai Ze, and Wu Jin
By using a linearly wavelength-scanning 1.55 μm laser source and a rotating plane mirror to control the direction of the illuminating laser beam, a laboratory-scale spotlight mode synthetic aperture ladar (SAL) is established. The SAL operates stably and the generating high resolution images are in accordance with the By using a linearly wavelength-scanning 1.55 μm laser source and a rotating plane mirror to control the direction of the illuminating laser beam, a laboratory-scale spotlight mode synthetic aperture ladar (SAL) is established. The SAL operates stably and the generating high resolution images are in accordance with the prospective results of imaging theory. Typical spotlight mode SAL images are illustrated, including images of a cooperative target, images of a diffusive target, constant tracking images, coherent superposition images and incoherent superposition images of the same target..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 628001 (2016)
Scattering
Vector Similarity Retrieval Algorithm in Particle Size Distribution Analysis of Forward Scattering
Wang Tian’en, Shen Jianqi, and Lin Chengjun
Recently, the vector similarity measurement (VSM) algorithm has been introduced to analyze particle size distribution (PSD) of the forward scattering. However, the retrieval result is not ideal for multi-modal distribution particle systems, especially for the particle distributions of more than three peaks. To satisfy Recently, the vector similarity measurement (VSM) algorithm has been introduced to analyze particle size distribution (PSD) of the forward scattering. However, the retrieval result is not ideal for multi-modal distribution particle systems, especially for the particle distributions of more than three peaks. To satisfy the need of predicting multi-peak distribution particle and enhancing common applicability, a modified iterative algorithm is proposed based on vector similarity measurement, and it is applied in retrieval calculation of PSD function. Simulated results and experimental researches show that the algorithm can also get the reasonable PSD with high measurement error..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 629002 (2016)
Spectroscopy
Study on Evolution of Lightning Return Stroke Channel Temperature by Near-Infrared Spectroscopy
Mu Yali, Yuan Ping, Wang Xuejuan, and Dong Caixia
According to the time-resolved spectra of three lightning return stroke processes, the temperature of the arc core channel and the peripheral luminous channel is calculated with different methods, and the evolution of channel temperature with time in the process of current decay is studied. The results show that the teAccording to the time-resolved spectra of three lightning return stroke processes, the temperature of the arc core channel and the peripheral luminous channel is calculated with different methods, and the evolution of channel temperature with time in the process of current decay is studied. The results show that the temperature of the core current channel is about 4000~5000 K higher than that of the peripheral luminous channel. The decrease of the channel temperature with time is very slow compared with that of the discharge current after the peak value occurs. Up to about 400 μs after the peak current occurs, the channel temperature still stays at about 20000 K, and the heat effect resulting from high temperature for such a long time is the main source of most lightning disasters..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 630001 (2016)
Wavelength Calibration of Charge Exchange Recombination Spectroscopic Diagnostic System on EAST
Yin Xianghui, Li Yingying, Fu Jia, Jiang Di, Feng Shuangyuan, Zhong Liujun, Lü Bo, Ye Minyou, and Wan Baonian
Charge exchange recombination spectroscopic (CXRS) diagnosis is a routine diagnostic method for the measurement of the temperature and the rotation velocity distribution of ions on nuclear fusion devices. The completely ionized carbon ion C6+ in plasma exchanges charge with high power neutral deuterium and radiates theCharge exchange recombination spectroscopic (CXRS) diagnosis is a routine diagnostic method for the measurement of the temperature and the rotation velocity distribution of ions on nuclear fusion devices. The completely ionized carbon ion C6+ in plasma exchanges charge with high power neutral deuterium and radiates the carbon line (C VI, 529.059 nm, n=8→7). By measuring the Doppler shift of C VI, the velocity of C6+ can be calculated. Precise wavelength calibration is a precondition for the accurate measurement of the velocity. The off-line and on-line wavelength calibration methods for the CXRS system on EAST (experimental advanced superconducting tokamak) device are introduced. The advantages and disadvantages of both methods are discussed in detail. Considering the special condition of the EAST plasma and the current situation of the CXRS diagnosis, an on-line calibration method using laser (wavelength 532.1 nm) is proposed. Simulations and experiments are performed for the calibration method and the results are consistent with those obtained via the commonly used calibration lamp..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 630002 (2016)
Research on Existence of Floating Reference Position in Human Body
Wang Jiao, Liu Rong, Yu Xuyao, Han Guang, and Xu Kexin
A measurement method based on the floating reference position is proposed, and the in vivo relative measurement of glucose concentration can be expected. The function of floating reference position is analyzed based on the analytical solution to the steady state diffuse equation in a semi-infinite medium. Moreover, theA measurement method based on the floating reference position is proposed, and the in vivo relative measurement of glucose concentration can be expected. The function of floating reference position is analyzed based on the analytical solution to the steady state diffuse equation in a semi-infinite medium. Moreover, the distribution of floating reference position for the three-layer skin model within the wavelength of 1000-1400 nm is investigated based on the Monte Carlo simulation, as well as the influence of absorption coefficient, scattering coefficient, and thickness of epidermis and dermis on floating reference position. A customized optical fiber system with multiple circles based on the superluminescent diode is presented for initial validation of the existence of floating reference position in human body. The simulation results show that the reference positions of the three-layer skin model exist in the wavelength range of 1000-1400 nm and are wavelength dependent, the influence of scattering coefficient is stronger than that of absorption coefficient, and the influence of epidermis thickness variation is stronger than that of dermis thickness variation. The in vivo experiments on three volunteers show that floating reference positions of human palm at 1050, 1219, 1314 nm exist, and are located within the radial distance from 1.25 mm to 1.75 mm. The experimental results are lower than the simulation results, with a maximum bias of 0.75 mm. The result is valuable to the design of optical probe applied in the floating reference measurement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 630003 (2016)
Vision, Color, and Visual Optics
Detection and Classification of Color Deficiency Before Vision Experiment
Ma Ruiqing, Liao Ningfang, and Shinomori Keizo
In the study of the color visual mechanism of color deficiency, the color types of each subject are detected and classified before experiment. 7 color deficiency subjects (three protanopes, one protanomalous, two deuteranomalous and one deuteranope) are participated in the test including pseudo-isochromatic plate testsIn the study of the color visual mechanism of color deficiency, the color types of each subject are detected and classified before experiment. 7 color deficiency subjects (three protanopes, one protanomalous, two deuteranomalous and one deuteranope) are participated in the test including pseudo-isochromatic plate tests (Ishihara and standard pseudo-isochromatic plates), hue ordering tests (Farnsworth D-15 and Farnsworth-Munsell 100-hue test) and quantitative measurement of color discrimination ability test(Cambridge color test). In comparison of test results with those of anomaloscope, the advantages and disadvantages of each test tool are analyzed. On this foundation, the procedure for detection and classification of color deficiency before vision experiments is described..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 633001 (2016)
X-Ray Optics
Ring Artifacts Correction Method Based on Dynamic Current for Cone Beam CT
Chen Siyu, Li Lei, Yan Bin, Xi Xiaoqi, Zhang Feng, Han Yu, Zhang Xiang, Deng Lin, and Li Jianxin
In the flat panel detector, the ring artifacts caused by the defective and response non-uniformity pixels will affect the quality of X-ray computed tomography (CT). In order to solve the issue, the linear correlation between pixel response and tube current is applied, and a ring artifact removal method based on detectoIn the flat panel detector, the ring artifacts caused by the defective and response non-uniformity pixels will affect the quality of X-ray computed tomography (CT). In order to solve the issue, the linear correlation between pixel response and tube current is applied, and a ring artifact removal method based on detector calibration is proposed. The pixels are detected, whose response is constant under different tube currents. Then the pixels with the response varying randomly or quickly reaching up to the maximum value are detected, and the correlation coefficients between each pixel channel response and the tube current are calculated. The pixels detected with the above mentioned methods are written into defective pixels map and corrected. With the reference of average response of all pixels under each tube current, the relationship between response and reference curve of the pixels under the same tube currents is calculated to obtain the identical correction matrixes of the detector. The output responses of the pixel are corrected according to the defective pixels map and the identical correction matrixes. Experimental results show that the proposed method can removes the ring artifacts effectively, and improves the signal to noise ratio of reconstruction image. In addition, it solves the problem of threshold selection with the existing defective pixal detection methods, which can be applied to different types of detectors..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 36, Issue 6, 634001 (2016)
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20