Contents
2014
Volume: 34 Issue 12
50 Article(s)
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Atmospheric Optics and Oceanic Optics
Research on Calibration Method of Sunphotometer in Semi-Arid Areas
Tong Jilong, Zhao Yanru, Zhao Zhiyuan, and Zhang Wenyu
Langley plot method and long-winded absolute method are used to calibrate sunphotometer. It is based on the obserbational data of sunphotometer obtained from the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) during the period from 1 September, 2006 to 31 August, 2007, homochronous surface Langley plot method and long-winded absolute method are used to calibrate sunphotometer. It is based on the obserbational data of sunphotometer obtained from the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) during the period from 1 September, 2006 to 31 August, 2007, homochronous surface conventional observation data, satellite data and radiosonde data. The results show that the error of scaling value may be large when selecting one eligible observation day. If the scaling value of several days in each band is averaged, the calibrate error between calculated and truth value will be still large. If the method of expected mean method and fitted mean method are screened, the scatter degree of daily scaling value will strikingly decrease and the standard deviation can be reduced by 70%~90%; After spots which deviate relatively distantly are deleted by using fitted mean method, the averge scaling value is close to the truth value..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1201001 (2014)
Extinction Coefficient of Stratified Atmosphere Measured by Sun-Photometer
Xu Mengchun, Xu Qingshan, Bian Jian, Wang Yiran, and Li Xuebin
Sun-photometer is one of the main instruments for ground-based detecting atmospheric optical parameter of whole atmospheric layer. The atmospheric optical parameters of lower atmosphere are more desiderated in some researches and projects. Based on the assumption of uniform parallel sphere of stratified atmosphere, a nSun-photometer is one of the main instruments for ground-based detecting atmospheric optical parameter of whole atmospheric layer. The atmospheric optical parameters of lower atmosphere are more desiderated in some researches and projects. Based on the assumption of uniform parallel sphere of stratified atmosphere, a new algorithm for average extinction coefficient of stratified atmosphere measured by sun-photometer is put forward. When dealing with the data measured by sun-photometer POM-02, the relative error of atmospheric optical depth gained by stratified atmospheric algorithm and whole atmospheric layer algorithm is less than 3%. The atmospheric average extinction coefficient of lower atmosphere got by stratified atmospheric algorithm is compared with the atmospheric average extinction coefficient by lidar. The results show that they have a good consistency. Therefore, the stratified atmospheric algorithm is feasible, and it extends the sun-photometer′s application..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1201002 (2014)
Fiber Optics and Optical Communications
Research on Influence of Polarization Crosstalk on the Zero Drift and Random Walk of Fiber Optic Gyroscope
Li Zizhong, Li Zhihong, Steve Yao, and Li Guohua
To solve the problem of the restricted accuracy of the polarization maintaining fiber optic gyroscope (PM-FOG), whose static parameters are influenced by its optical path polarization crosstalk errors, from the view of practical applications, the mechanism of polarization crosstalk errors in light path caused by unsatiTo solve the problem of the restricted accuracy of the polarization maintaining fiber optic gyroscope (PM-FOG), whose static parameters are influenced by its optical path polarization crosstalk errors, from the view of practical applications, the mechanism of polarization crosstalk errors in light path caused by unsatisfactory optical devices and fused points′ axis angle errors is studied. Based on the Jones matrix and correlation matrix, the PM fiber′s birefringence variable which varies with temperature change is introduced, the optical transmission model of PM-FOG in variable temperature fields is built, and the effect of polarization crosstalk errors on PM-FOG zero drift and random walk in variable temperature fields is analyzed and estimated. Meanwhile, the related experiments are carried out to study the effect of fiber coils polarization crosstalk on its static parameters in variable temperature fields. The experimental results and analysis results of model are in agreement, which shows that the model is reasonable..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1206001 (2014)
Research on Self-Healing Method of Multi-Agent Collaboration Fiber Optic Sensor Network Based on Optical Switch and Graph Theory
Zeng Tian, Liang Dakai, Zeng Jie, Zhang Xiaoli, and Meng Jing
Regarding to the link failure of fiber optic sensor network in multi-agent collaboration health monitoring system, a self-healing method of fiber optic sensing network based on optical switch and graph theory is proposed. Using the graph theory, the connectivity of fiber optic sensor network link with optical switches Regarding to the link failure of fiber optic sensor network in multi-agent collaboration health monitoring system, a self-healing method of fiber optic sensing network based on optical switch and graph theory is proposed. Using the graph theory, the connectivity of fiber optic sensor network link with optical switches is expressed, the switching strategy when link failures happen in fiber optic sensor network is studied, and the self-healing of failure fiber Bragg grating (FBG) sensor′ signals is realized. Using the aviation aluminum structure as the experimental object and aiming at the typical link failures of fiber optic sensor network, its self-healing effect based on optical switch and multi-agent collaboration through contrast experiment is studied. The experimental results show that, with optical switch and multi-agent collaboration, the recognition accuracy is improved by 10.02 mm compared with that of unrepaired model, which is only lower 3.61 mm compared with that of health model, showing that optical switch and multi-agent collaboration can effectively improve the loading recognition accuracy and the reliability of fiber optic sensor network..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1206002 (2014)
Highly Sensitive Optical Nanofiber Bio-Chemical Sensor Based on Magnetic Nanoparticles Amplication
Dai Fang, Li Kaiwei, Zhou Wenchao, Zhang Wei, Yu Muxin, Liu Changqing, and Wu Yihui
In order to meet the requirements of high sensitivity and specificity of clinical diagnosis, the effects of magnetic nanoparticles (MNPs) on the transmission performance of optical nanofiber are studied, as well as the possibility of MNPs functioned as labels to enhance the sensitivity of bio-chemical detection and theIn order to meet the requirements of high sensitivity and specificity of clinical diagnosis, the effects of magnetic nanoparticles (MNPs) on the transmission performance of optical nanofiber are studied, as well as the possibility of MNPs functioned as labels to enhance the sensitivity of bio-chemical detection and the purificaiton of the determinand. The fabrication process of tapered optical nanofiber sensors, functionalization of optical nanofiber biosensors and MNPs are presented. Experiments are designed, the amplication function of MNPs is verified, and single MNP with the diameter from 200 nm to 300 nm is successfully resolved by optical nanofiber biosensor. The results of experiments demonstrate that the project of using MNPs as separation, purification and enhancing of sensitivity, can work well on optical nanofibers..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1206003 (2014)
Polarization Demultiplexing Method for Intensity-Modulation Direct-Detection Optical Communication Systems
Zhou Xinyu, Yan Lianshan, Yi Anlin, Chen Zhiyu, Pan Wei, and Luo Bin
A simple and effective polarization demultiplexing method employing improved optical splitter and digital signal processing (DSP) algorithm for intensity-modulation direct-detection (IM/DD) optical communication systems is proposed. Simulation results show that in a 2×40 Gb/s polarization-division-multiplexing intA simple and effective polarization demultiplexing method employing improved optical splitter and digital signal processing (DSP) algorithm for intensity-modulation direct-detection (IM/DD) optical communication systems is proposed. Simulation results show that in a 2×40 Gb/s polarization-division-multiplexing intensity-modulation direct-detection (PDM-IM/DD) optical transmission system, the PDM signals can be effectively separated. The DSP algorithm can rapidly converge with the receiver sensitivity of -2.3 dBm at bit error rate of 10-4..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1206004 (2014)
Extended Kalman Based Polarization and Carrier Phase Quickly Tracking for PDM-16QAM
Cao Guoliang, Yang Yanfu, Wang Fei, Cui Lantao, Rong Ning, Gu Jian, and Yao Yong
In the coherent receiver of polarization division multiplexing (PDM) optical communication system, the modules of polarization demultiplexing and carrier phase recovery are required. Extended Kalman filter is used into polarization division multiplexing-16 quadrature amplitude modulation (PDM-16QAM) coherent receiver tIn the coherent receiver of polarization division multiplexing (PDM) optical communication system, the modules of polarization demultiplexing and carrier phase recovery are required. Extended Kalman filter is used into polarization division multiplexing-16 quadrature amplitude modulation (PDM-16QAM) coherent receiver to achieve polarization and phase tracking quickly and accurately. In the single channel 112 Gb/s PDM-16QAM optical communication system, the simulation results show that the maximum polarization rotation rate of extended Kalman filter tracking is nearly 100 times faster than that of Cascade multimode algorithm. Meanwhile, Kalman filter also has a high accuracy, and the convergence speed and accuracy can be controlled by adjusting the tuning parameters.Specifically, only 0.2 dB sensitivity penalty at the bit error rate (BER) limit of 10-3 is induced when extended Kalman filter is applied on the signal with 100 kHz line width and 18 Mrad/s polarization rotation. A long-haul transmission simulation is raised to test the performance of extended Kalman filter..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1206005 (2014)
Research on the Characteristic of Bias Error and Noise Analysis Method of Fiber Optic Gyroscope
Yang Yuanhong, and Meng Chenxue
Fiber optic gyroscope (FOG) is a typical optical fiber interferometer. The nonreciprocal errors in its output are mainly induced by parasitic interferences and its zero bias error demonstrates a periodical characteristic. The sinusoidal noise induced by the parasitic interferences is found to be the main impact factor Fiber optic gyroscope (FOG) is a typical optical fiber interferometer. The nonreciprocal errors in its output are mainly induced by parasitic interferences and its zero bias error demonstrates a periodical characteristic. The sinusoidal noise induced by the parasitic interferences is found to be the main impact factor of bias error by using the Allan variance analysis method. By adding the sinusoidal noise to the original FOG output, we find that the “rate ramp and rate random walk” sections in the Allan variance curve are due to the sinusoidal noise. The sinusoidal noise identification method is implemented by using wavelet analysis and Fourier analysis. Based on this, the calculation methods for bias instability coefficient, angle random walk coefficient and quantization noise coefficient are proposed with wavelet analysis and Allan variance analysis and validated in experiment..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1206006 (2014)
Investigation on the Vibration Characteristic of Fiber Vibration Sensor Based on a Core-Offset Structure
Ma Lin, Guo Xinchun, Qi Yanhui, and Jian Shuisheng
An optical fiber vibration sensor based on a core-offset structure is proposed and demonstrated. This kind of fiber sensor shows a nice comb filter property and has a high extinction ratio. The curvature sensing characteristic of the core-offset structure is analyzed. The experiment results show that this kind of sensoAn optical fiber vibration sensor based on a core-offset structure is proposed and demonstrated. This kind of fiber sensor shows a nice comb filter property and has a high extinction ratio. The curvature sensing characteristic of the core-offset structure is analyzed. The experiment results show that this kind of sensor exhibits a linear response to bending curvature. The vibration characteristic of the sensor is studied at this basic. And the vibration responses of the sensor with the input laser wavelengths located in the linear responding area and in the transmission peaks or dips are analyzed. The results show that this kind of vibration sensor exhibits a fine vibration response with the input laser wavelength located in the linear responding area, just like Mach-Zehnder fiber interferometer. In addition, the sensor shows a nice noise characteristic when there is no vibration, which means good application prospects..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1206007 (2014)
Image Processing
Mode Analysis of Unit Cell Superlens and Study on Its Sub-Wavelength Imaging Performance
Yu Muxin, Zhou Wenchao, and Wu Yihui
A superlens which can work at visible wavelength and whose work wavelength can be manipulated is proposed. It consists of a plasmonic metal film layer and two dielectric film layers. The relationship between the dielectric layer and the surface plasmon waveguide mode is analyzed, and its sub-wavelength imaging law is gA superlens which can work at visible wavelength and whose work wavelength can be manipulated is proposed. It consists of a plasmonic metal film layer and two dielectric film layers. The relationship between the dielectric layer and the surface plasmon waveguide mode is analyzed, and its sub-wavelength imaging law is given. The results show that a sub-wavelength image with high transmittance and resolution of λ/6 can be obtained in the range of 365~515 nm. The fabrication tolerance and surface roughness can be greatly reduced, ascribed to its quite simple structure. Its simple structure and excellent sub-wavelength imaging capability opens a door for potential applications, such as sub-wavelength lithography, bio-microscopy and high intensity storage..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1210001 (2014)
Imaging Systems
RCS Simulation of Targets in THz Band Based on Fast Physical Optics Algorithm
Jiang Yuesong, Zhang Zhiguo, and Hua Houqiang
The method for the calculation of radar cross section (RCS) of targets in terahertz (THz) band based on fast physical optics (FPO) algorithm is presented. The scatterer is divided into subdomains and the scattering characteristics of each subdomain are computed after the phase compensation. Through interpolation, phaseThe method for the calculation of radar cross section (RCS) of targets in terahertz (THz) band based on fast physical optics (FPO) algorithm is presented. The scatterer is divided into subdomains and the scattering characteristics of each subdomain are computed after the phase compensation. Through interpolation, phase correction and aggregation, the scattering characteristic of the whole scattering body is abtained, and the applications of FPO in THz band are discussed. Simulation results show that the targets′ RCS calculation by FPO in THz band can greatly improve the computational efficiency and save computing time in the premise of ensuring the accuracy. This research has an important significance for fast target recognition and imaging in THz band..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1211001 (2014)
Impulse Noise Removal Method Based on Moreau Envelope Smoothing l1/TV Norm Model
Wang Bin, Hu Liaolin, Cao Jingjing, Xue Ruiyang, and Wang Yaping
Impulse noise is one of the main causes of image degradation, low density impulse noise can be easily removed while high density impulse noise removal is more difficult. In order to effectively remove high density impulse noise and to keep edges and texture better, an algorithm based on Moreau envelope smoothing l1/totImpulse noise is one of the main causes of image degradation, low density impulse noise can be easily removed while high density impulse noise removal is more difficult. In order to effectively remove high density impulse noise and to keep edges and texture better, an algorithm based on Moreau envelope smoothing l1/total variation (l1/TV) norm model is proposed. This algorithm has advantages such as contrast and morphological invariance and absence of local blur. Since the convex objective function in l1/TV model is non-differentiable and thus difficult to solve, smoothing the total variation part by utilizing decoupled Moreau envelope is proposed. As the smoothed function which generates an iterative form of analytical solution is the differentiable tight lower bound of the original function, it is provable that they have the same solution. The simulation results show that the algorithm effectively removes noise with edges and texture kept. In addition, the combined acceleration steps are proposed to greatly improve the speed of convergence..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1211002 (2014)
Polarization Analysis of the Telescope System Used for Space Target Polarization Detection
Wang Guocong, Wang Jianli, Zhang Zhenduo, Ming Ming, Zhang Bin, and Zeng Wei
The polarization imaging system based on large aperture ground-based adaptive telescope can acquire both intensity image and polarization image at the same time. Richer information for detecting and identifying space target can be provided by the combination of intensity and polarization. Because the polarization-maintThe polarization imaging system based on large aperture ground-based adaptive telescope can acquire both intensity image and polarization image at the same time. Richer information for detecting and identifying space target can be provided by the combination of intensity and polarization. Because the polarization-maintaining design of the 1.23 m ground-based adaptive telescope is ignored, the telescope′s polarization properties on propagation should be known before experiments. But it is difficult to calibrate the polarization properties of large aperture telescope. To analyze the polarization properties of the 1.23 m ground-based adaptive telescope, an analysis model based on coherent matrices and ray tracing formulas is constructed. By simulation, impact of the optical system on the accuracy of polarizing detection is found. An improved scheme to decrease the deviation of polarizing detection is given and its effectiveness is identified by the model constructed above..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1211003 (2014)
Phased Array Imaging Algorithm for Endoscopic Ultrasound Based on Synthetic Aperture Imaging Technique
Zhang Chuang, Chen Xiaodong, Wang Yi, Li Ying, Jiao Zhihai, and Yu Daoyin
With a 16-element transducer whose aperture size is 2.32 mm, an experimental endoscopic ultrasonic phased array imaging system which has 16 channels is constructed. A novel phased array imaging algorithm (PAI) is proposed. The algorithm applies the image lines obtained by the delay and sum algorithm (DAS) as input dataWith a 16-element transducer whose aperture size is 2.32 mm, an experimental endoscopic ultrasonic phased array imaging system which has 16 channels is constructed. A novel phased array imaging algorithm (PAI) is proposed. The algorithm applies the image lines obtained by the delay and sum algorithm (DAS) as input data, and takes advantage of the synthetic aperture imaging which picks out the coherent samples of the recorded echoes and sums these samples. The algorithm finally obtains a high resolution image. The algorithm is dynamically focused in both transmission and receiving. With FieldII, the results of simulation indicate that PAI can increase the lateral resolution by 93.68% and 17.5% respectively, compared with DAS and dynamic receiving focusing algorithm (DRF). The experimental results indicate that PAI can increase the lateral resolution by 92.78% and 14.69% respectively, compared with DAS and DRF. The simulation and experiment finally verify the feasibility of the phased array imaging algorithm and the experimental system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1211004 (2014)
Calibration and Imaging Model of Light Field Camera with Microlens Array
Zhang Xu, and Li Chen
The light field imaging with microlens array is modeled through analyzing three fundamental factors, such as space, lens, and sensor. The spatial multiplexing is explained and the relationship between the light field and the pixel in raw image is described. Based on the phase shifting, a calibration method is proposed The light field imaging with microlens array is modeled through analyzing three fundamental factors, such as space, lens, and sensor. The spatial multiplexing is explained and the relationship between the light field and the pixel in raw image is described. Based on the phase shifting, a calibration method is proposed to determine the centers of microlens, the corresponding relationship between the pixel and the microlens, and the character of the microlens vignetting. The experiment is conducted on a commercial light field camera, Lytro. The light field is decoded from the raw image and the refocus image and all-focus image is created from the obtained light field. The experiment results confirm the proposed model and calibration method is valid..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1211005 (2014)
Instrumentation, Measurement and Metrology
Modulation Transfer Function Measurement of Image Motion of Aerial Camera Based on Slanted-Edge Method
Sun Chongshang, Wang Qi, Ding Yalin, Wang Dejiang, Meng Fanhao, and Zhang Lei
Image motion of aerial camera during exposure time leads to the degradation of image quality, so image motion compensation system is essential for aerial camera. Subjective criterion, namely image motion is distinguished by human eyes, is always used to evaluate whether the performance of the image motion compensation Image motion of aerial camera during exposure time leads to the degradation of image quality, so image motion compensation system is essential for aerial camera. Subjective criterion, namely image motion is distinguished by human eyes, is always used to evaluate whether the performance of the image motion compensation system meets the design requirements. Subjective criterion is usually influenced by people, and only provides qualitative evaluation. In order to establish the direct relationship between image quality of aerial camera and other index of image motion compensation system, modulation transfer function (MTF) measurement of image motion based on slanted-edge method is presented. Then experiment is designed to verify this method. Image motion caused by scanning of aerial camera is simulated by the rotation of turntable, and the MTF of image motion is obtained by two ways. One is measured by slanted-edge method, and the other one is calculated by theoretical model. Experimental results show that when spatial frequency is 0.10 cycle/pixel and the turntable rotates at 3, 5, 8°/s, the difference between the MTF obtained by the two methods is 0.77%, 1.15%, and 4.91%, thus the effectiveness of this method is demonstrated..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1212001 (2014)
Research on Multiplicity of Solution in Space Camera Image Motion Measurement Based on Images from TDI Sensor Overlapped Area
Liu Haiqiu, Wang Dong, and Xu Shuyan
The multiplicity of solution in image motion estimation method based on images captured by overlapping time delay integration (TDI) imaging sensors is addressed, and a method to eliminate the multiplicity of solution by taking the optimum of smoothness evaluation function as the only solution of image motion is proposeThe multiplicity of solution in image motion estimation method based on images captured by overlapping time delay integration (TDI) imaging sensors is addressed, and a method to eliminate the multiplicity of solution by taking the optimum of smoothness evaluation function as the only solution of image motion is proposed. The existence of the multiplicity of solution is analyzed. An evaluation function is proposed to evaluate the smoothness of each solution, and the minimized evaluation function is taken as the optimal solution of image motion. The optimum is found by using the conjugate gradient method (CGM). A single-solution result is obtained with an error of 0.13 pixel, showing that the added smoothness evaluation function is feasible to solve the problem of multiplicity of solution in image motion measurement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1212002 (2014)
Two-Flat Test Solution Based on Iterative Algorithm
Gao Bo, Li Qiang, Liu Ang, He Yuhang, and Chai Liqun
A method for reconstruction surfaces map on iterative algorithm is presented. According to flipping and rotationg one of the two plates, four measurements are generated. The formulas are directly derived from four measurements that require rotation or flipping operations. Three trial surfaces are initialized, then the A method for reconstruction surfaces map on iterative algorithm is presented. According to flipping and rotationg one of the two plates, four measurements are generated. The formulas are directly derived from four measurements that require rotation or flipping operations. Three trial surfaces are initialized, then the new surfaces are calculated according to the formulas. The trial surfaces are replaced by the new surfaces. The experiment shows that this method can achieve a deviation of 0.1 nm, which only requires no more than 50 iterations．And the error sources are analyzed in detail. The total measuring error of this method is 1.417 nm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1212003 (2014)
Measurement of Photonic Isofrequency Curves and Band Struture Based on the Abbe Sine Condition
Yuan Xiaowen, Wang Qi, Chen Changqing, Zhang Bo, and Sun Liaoxin
Based on the transmission characteristics of electromagnetic waves in periodic nanomaterial and the optical Abbe sine condition, the optical system that can measure photonic isofrequency curves and band structures is proposed. By using a grating spectrometer equipped with a two-dimensional CCD and an infinite tube lengBased on the transmission characteristics of electromagnetic waves in periodic nanomaterial and the optical Abbe sine condition, the optical system that can measure photonic isofrequency curves and band structures is proposed. By using a grating spectrometer equipped with a two-dimensional CCD and an infinite tube length microscope objective that can directly transform the wave vector space into real space, the information of photonic isofrequency curves and band structures are obtained with a snapshot, leading to a simple, rapid and nondestructive detection method. This experimental scheme is applied to measure a two-dimensional periodic nanomaterial which is prepared by using self-assembly technology. By comparing experimental results and theoretical calculation, feasibility and reliability of this system are verified. It indicates an unique advantage in studying the optical property of the periodic nonmaterial..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1212004 (2014)
Study on Effect of Subset Size on Digital Image Correlation with a New Method
Liang Zhenning, Yin Bo, and Wang Shigang
Subset size selection is an essential step for digital image correlation which affects the calculation accuracy greatly. The effects of pixels in a subset on calculation result are investigated. A new method is developed to deal with the problem. In the method, all the pixels in a subset are not treated equally as the Subset size selection is an essential step for digital image correlation which affects the calculation accuracy greatly. The effects of pixels in a subset on calculation result are investigated. A new method is developed to deal with the problem. In the method, all the pixels in a subset are not treated equally as the traditional method. Coefficients are set to each pixel rely on the importance of them to identify a subset from target images which are calculated by the normal distribution based on the distances between them and the central pixel. Similar to subset size selection in traditional digital image, it is availabe to select appropriate number of pixels in subsets according to test conditions. The effect of pixels at the edge of subsets on correlation calculation is somewhat alleviated. Thus, the calculation accuracy is improved..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1212005 (2014)
Analysis on the Parameter of Lyot Stop in Internally Occulting Refractive Coronagraph
Bu Heyang, Zhang Hongxin, Lu Zhenwu, and Zhang Zhengzheng
Coronagraph is a device used to observe the corona by making a total solar eclipse-like image on the image plane. The dark background of the image plane is provided by the structures used to suppress the stray light in the coronagraph. The structure named Lyot stop is used to remove the diffracted ring formed by diffraCoronagraph is a device used to observe the corona by making a total solar eclipse-like image on the image plane. The dark background of the image plane is provided by the structures used to suppress the stray light in the coronagraph. The structure named Lyot stop is used to remove the diffracted ring formed by diffracted light from the edge of the front aperture. The structure parameters of the Lyot stop are adjusted based on the diffracted light of different wavelengths. The parameters of the Lyot stop are confirmed for removing the diffracted light entirety and enhancing the energy on the image plane radiated by solar corona. The cause of the diffraction rings is analyzed by the simulation of the internally occulting refractive coronagraph. The design and the parameters of the Lyot stop are determined by theoretical analysis. The feature size of the diffracted ring is matched with the parameters of the Lyot stop by the processing of the imaging. The effect of the stray-light suppression based on Lyot stop is achieved by the experiments. The capability of the stray-light suppression of coronagraph is improved..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1212006 (2014)
Study on a Novel Linear Displacement Sensor Based on the Orthogonal Modulating Light Intensity
Peng Donglin, Fu Min, Zhu Ge, Zheng Fangyan, and Li Yan
A novel linear displacement detected method based on electrical travelling wave generation using alternating light field standing wave is proposed. By modulating the displacement values to the changes of phase difference of electrical travelling wave signal, the spatial displacement is measured by using the method of pA novel linear displacement detected method based on electrical travelling wave generation using alternating light field standing wave is proposed. By modulating the displacement values to the changes of phase difference of electrical travelling wave signal, the spatial displacement is measured by using the method of phase discrimination. In order to optimize the sensor parameters and improve the measurement precision, the error characteristics, caused by light scatting phenomenon, are studied under different parameter conditions. Firstly, according to the characteristics of the sensor structure, measurement error caused by light field distribution is theoretically analyzed and a three-dimensional simulation model is built using the Tracepro software to analyze the light field distribution under different parameter conditions. And then, the relationship between the light field distribution under different parameters and error characteristics is obtained by experimental verification. Finally, the sensing parameters can be optimized based on the simulation and experimental results. The preliminary experimental results prove that the measuring errors of the sensor are controlled within ±0.5 μm for an effective measuring range of 108 mm. A reliable basis of theoretic and technical is provided for the further design optimization and precision improvement of sensor..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1212007 (2014)
Lasers and Laser Optics
Design of Single-Longitudinal-Mode Operation in a Solid State Yellow Laser with Twisted-Mode-Cavity
Li Xiaoli, Tan Yidong, Yang Changxi, and Zhang Shulian
All-solid-state yellow Raman lasers working in the spectra range of 560~590 nm have promising development in recent years. However, it is still facing the problem of yellow spectrum impurity resulting from the multimode operation within the laser resonator. To solve this problem, a novel design of single-longitudinal-mAll-solid-state yellow Raman lasers working in the spectra range of 560~590 nm have promising development in recent years. However, it is still facing the problem of yellow spectrum impurity resulting from the multimode operation within the laser resonator. To solve this problem, a novel design of single-longitudinal-mode yellow Raman laser based on the twisted-mode-cavity combined with Raman couple cavity is proposed. It can suppress the multimode oscillations at the fundamental wavelength caused by the spacial hole burning effect in the laser gain medium, and then realize thesingle-longitudinal-mode operation at the yellow wavelength. The Raman couple cavity consists of a L-shape fundamental resonator and a linear Raman resonator, which can benefit from high intensity of intracavity fields to reduce the laser threshold. It also has advantage of flexible adjustment to optimize different resonators separately for the best laser performance. This design is of practical significance to enable single-lungitudinal-mode yellow laser source with milliwatt output power, which paves the way for applying yellow lasers in biomedicine, laser-guide-star and space target recognition..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1214001 (2014)
Z-Scan Technique of Arbitrary Beam Shape and Medium Thickness
Zhao Gang, Lü Xinjie, and Qin Yiqiang
Based on split-step fast Fourier transform method and coordinate transformation, we establish simulation methods of propagation and focusing of arbitrary beam shape in the light-induced refractive index change medium, in order to calculate Z-scan opening and close aperture fitted curves of arbitrary beam shape and mediBased on split-step fast Fourier transform method and coordinate transformation, we establish simulation methods of propagation and focusing of arbitrary beam shape in the light-induced refractive index change medium, in order to calculate Z-scan opening and close aperture fitted curves of arbitrary beam shape and medium thickness. Under the conditions of thin medium and Gaussian beam, the fitting curve coincides with the classical algorithm. In the case of flat-top beam, the fitting results of this method are consistent with the experimental data. By using this method, the nonlinear absorption and nonlinear index coefficient of LiTaO3 crystal are measured. Finally, the Z-scan process of Gaussian beam and vortex beam in thick media is analyzed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1214002 (2014)
Machine Vision
Optimal Positioning of Forward Installed Square LED Arrays for Machine Vision System
Hao Fei, Shi Jinfei, Zhu Songqing, Zhang Zhisheng, Han Yali, and Chen Ruwen
Positioning of forward symmetrically installed square light-emitting diode (LED) arrays are studied to achieve uniform illumination with which high quality images can be gathered for machine vision measurement. The optimization method is used to solve this problem because the optical axes of the arrays are not perpendiPositioning of forward symmetrically installed square light-emitting diode (LED) arrays are studied to achieve uniform illumination with which high quality images can be gathered for machine vision measurement. The optimization method is used to solve this problem because the optical axes of the arrays are not perpendicular to the irradiated plane, which can′t be solved by analytic method. The variance is chosen to establish the mathematical model of goal function on the base of the structure characteristics of LEDs. The simulated annealing (SA) algorithm is chosen for solving the non-convex objective function. An experiment system is developed for illumination photometry. The sizes of area with 95% of uniformity of the analytic method are a little larger than those of the optimization based method. The maximum difference is within 4%. The results show that the optimization objective is reasonable and the method is feasible..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1215001 (2014)
Human Action Recognition by Leaning Pose Dictionary
Cai Jiaxin, Feng Guocan, Tang Xin, and Luo Zhihong
A framework for human action recognition by learning pose dictionary based on human contour representation is proposed. A new pose feature based on Procrustes analysis and local preserving projection is proposed, which can extract shape information from human motion video which is invariant to translation, scaling and A framework for human action recognition by learning pose dictionary based on human contour representation is proposed. A new pose feature based on Procrustes analysis and local preserving projection is proposed, which can extract shape information from human motion video which is invariant to translation, scaling and rotation. Moreover, it can extract discriminative subspace information when preserving local manifold structure of human pose. After the pose feature is extracted, a human action recognition framework based on pose dictionary learning is proposed. Class-specific dictionaries are trained individually on all training frames of each class to build the whole pose dictionary by concatenating all class-specific dictionaries. The test video is classified with the minimum reconstruction error on the learned dictionary. Experimental results on Weizmann and MuHAVi-MAS14 dataset demonstrate proposed method outperforms most classical methods. Especially, classification rate of this method on MuHAVi-MAS14 dataset achieves a considerable boost compared with that of state-of-the-art approaches..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1215002 (2014)
Three Dimensional Point Cloud Splicing of Tree Canopy Based on Multi-Source Camera
Zhou Wei, Ma Xiaodan, Zhang Lijiao, Guo Cailing, and Liu Gang
In order to guide the pruning, flower thinning and harvesting of fruit trees in orchard, a novel vision system which combines a color-camera system with a photo mixing detector (PMD)-camera is constructed. For the three-dimensional coordinate information of target scene acquired by the PMD camera, effective point cloudIn order to guide the pruning, flower thinning and harvesting of fruit trees in orchard, a novel vision system which combines a color-camera system with a photo mixing detector (PMD)-camera is constructed. For the three-dimensional coordinate information of target scene acquired by the PMD camera, effective point cloud combining PMD amplitude image with density-based spatial clustering of applications with noise (DBSCAN) algorithm is extracted. Multi-source information fusion is completed with the result of image registration in the previous studies. Primary component analysis algorithm (PCA) is used to get the initial state of the point cloud at different locations, which is called prealignment. Accurate splice between two point clouds is realized by the iterative closest point (ICP) algorithm based on the least square method to get the optimal matching. Coordinate transformations are obtained by singular value decomposition (SVD) after prealigment and accurate splice. Several groups of experiments are used for verification, which show the average error of multi-view point cloud splicing reaches 2.62 cm and can better make up full three dimensional display of apple tree canopy without missing data than a single angle shot..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1215003 (2014)
Study on Close-Range Photogrammetry Based on Nonparameteric Measurement Model
Long Changyu, Zhu Jigui, Guo Yin, Lin Jiarui, and Ye Shenghua
Because of the advantage of wide measurement range, high measurement accuracy and high efficiency, the close-range photogrammetry plays more and more important role in large-size accurate measurement tasks. The self-calibration measurement model optimized via bundle adjustment is considered to be the most reliable techBecause of the advantage of wide measurement range, high measurement accuracy and high efficiency, the close-range photogrammetry plays more and more important role in large-size accurate measurement tasks. The self-calibration measurement model optimized via bundle adjustment is considered to be the most reliable technique to high-accuracy close-range photogrammetry. As more and more off-the-shelf single lens reflex (SLR) cameras are adopted to three-dimensional measurement applications, the measurement results are not ideal compared with that of professional cameras. After being analyzed carefully, the self-calibration parameterized model has some limitations to the improvement of measurement accuracy in addition to the issues inherent in the qualities of cameras. In order to solve the problem, the close-range photogrammetry without relying on camera internal parameters is studied. The nonparameteric calibration method is proposed, which is suitable to the calibration of large-field cameras. The nonparameteric measurement model based on orientation information is established after the image points is matched and the initial value are determined. The three-dimensional coordinates of target points can be solved accurately via the optimization of bundle adjustment. Compared with measurement results of traditional photogrammetry, it is proved that our method is effective to improve the three-dimensional measurement accuracy with large-field SLR cameras..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1215004 (2014)
Stereo Panorama Generation from the Train-Borne Video
Wang Shengchun, Luo Siwei, Huang Yaping, Wang Liang, and Dai Peng
The patrol train with picture pick-up device has been used for railway environment monitoring. A method to generate the stereo panorama from forward motion train-borne video using only one camera to acquire the panoramic stereo information of the entire scene is presented. On the basis of the geometric priori informatiThe patrol train with picture pick-up device has been used for railway environment monitoring. A method to generate the stereo panorama from forward motion train-borne video using only one camera to acquire the panoramic stereo information of the entire scene is presented. On the basis of the geometric priori information of the scene and known camera parameters, a set of trapezoidal stripes is extracted from a video sequence continuously, whose width is automatically adjusted according to the vehicle speed, and the stripes are stitched into a panoramic image after aligning all the stripes by homography transformation. The accurate geometric model is built to generate the panoramic stereo pairs. The experimental results show that the method can effectively and efficiently generate a stereoscopic panorama. Compared with the original video format, the stereo panorama requires less storage space, possesses wider field of view and greater realism, and enables the inspector to perform quick examination and immersive browsing..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1215005 (2014)
Improved Zhang′s Calibration Method and Experiments for Underwater Binocular Stereo-Vision
Li Guangle, Huang Wenyou, Liu Qingsong, and Deng Zhiyan
An improved Zhang′s calibration method is proposed, combined with Jean-Yves Bouguet vanishing point calibration method, aiming at improving the accuracy of underwater camera calibration and the establishment of nonlinear mathematical model which has a comprehensive consideration of radial distortion and tangential distAn improved Zhang′s calibration method is proposed, combined with Jean-Yves Bouguet vanishing point calibration method, aiming at improving the accuracy of underwater camera calibration and the establishment of nonlinear mathematical model which has a comprehensive consideration of radial distortion and tangential distortion on cameras underwater. In order to verify the feasibility and robustness of the improved method, underwater calibration experiments are carried out compared with Zhang′s calibration method. The experimental results show that both of the two methods have strong robustness, however, compared with Zhang′s calibration method, the improved one can achieve higher accuracy with smaller reprojection average error and the calibration results are closer to the actual results..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1215006 (2014)
Nonlinear Optics
Nonlinear Pulse Width Change of Nonchirped Pulse Versus Crystal Mismatch by Cascaded Harmonic Generation
Li Keyu, Feng Bin, Sun Li, Xiang Yong, Guo Yi, Huang Zheng, Sun Zhihong, Li Qing, Xie Na, Ye Rong, and Wang Xiaodong
Based on the cascaded frequency-harmonic mechanism during the course of nonlinear compression of nonchirped laser pulse, the sensitive factor affecting the pulse compression of crystal phase mismatch is analyzed theoretically and validated experimentally. After the input fundamental pulse (namely, 1ω, 0.8-μm wavelengthBased on the cascaded frequency-harmonic mechanism during the course of nonlinear compression of nonchirped laser pulse, the sensitive factor affecting the pulse compression of crystal phase mismatch is analyzed theoretically and validated experimentally. After the input fundamental pulse (namely, 1ω, 0.8-μm wavelength and 278-fs pulse width) propagates through the type I second harmonic generation β-BaB2O4(BBO) crystal, the 1ω output pulse width is shortened firstly and widened again with the increase of crystal phase mismatch. This trend can be summarized as the “U” grapheme nonlinear change. The output pulse width is shortened to the least value and the highest compression ratio of pulse width is obtained when the crystal mismatch is 40 mm-1..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1219002 (2014)
Optical Design and Fabrication
Design of Aspheric Fisheye Lens and Study of Distortion Correction Algorithms
Zhang Baolong, Li Dan, Zhang Shaojing, Li Hongrui, Yang Jichao, and Wang Jingyun
A design method of aspheric fisheye lens is proposed. Based on the requirements of the lens of panoramic imaging system, a kind of ultra-wide-angle fisheye lens is designed, which only consists of a spherical glass lens and three aspherical plastic lenses. The maximum diameter of imaging aperture is 15.3 mm, the workinA design method of aspheric fisheye lens is proposed. Based on the requirements of the lens of panoramic imaging system, a kind of ultra-wide-angle fisheye lens is designed, which only consists of a spherical glass lens and three aspherical plastic lenses. The maximum diameter of imaging aperture is 15.3 mm, the working distance behind is 2.158 mm, the total length of system is 11.44 mm, the focal length is 0.97 mm, the viewing angle is 210°, and the modulation transfer function (MTF) curve reaches 0.35 at 60 lp/mm. Furthermore, a kind of distortion correction algorithm for fisheye lens is built, which calculates the position of ideal image point using actual image poin according to the obtained distortion curve and distortion model. The algorithm can correct the distorted image taken by fisheye lens to image without distortion suitable for the human eye view, which is simple and effective. The algorithm is applied in car panoramic display system. It is verified to be accurate and reasonable, through the comparison between the real image taken by fisheye lens and the corrected image..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1222001 (2014)
An Error Calibration Method against Aberration in Long Focal Length Measurement
Jiang Yao, Bai Jian, Luo Jia, and Li Qiang
A high accuracy calibration method for errors resulted from aberration in long focal length measurement, is presented. Generally, Gaussian equation is used for calculation without consideration of the errors caused by aberration. However, the errors become the key factor affecting the accuracy in the measurement systemA high accuracy calibration method for errors resulted from aberration in long focal length measurement, is presented. Generally, Gaussian equation is used for calculation without consideration of the errors caused by aberration. However, the errors become the key factor affecting the accuracy in the measurement system, based on divergent light, of a large aperture and long focal length lens. An effective way is proposed to calibrate the errors, with detailed analysis of the long focal length measurement based on divergent light and Talbot interferometry. Aberration errors are obtained by numerical method and compared with results simulated by Zemax. Then, auto-correction is achieved with the help of Visual C++ software and the modified measurement results of 13500 mm focal length lens and 31251 mm focal length lens reveal that the relative accuracy is better than 0.007% and 0.022%, respectively. By comparing the modified relative accuracy with relative accuracy obtained in interferometer measurement, the proposed method is proved to be highly effective and reliable..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1222002 (2014)
Optical System Design for Ultraviolet-LED Curing Based on the Structure of Freeform Surface
Li Mengyuan, Sun Jialue, Zhang Dawei, and Li Baicheng
In the traditional printing, curing light source always uses high pressure mercury lamp, metal halide lamp and so on. The traditional light source of ultraviolet curing technology has been matured. But because of the light source itself and the limitations of the optical system, the linear light radiation intensity of In the traditional printing, curing light source always uses high pressure mercury lamp, metal halide lamp and so on. The traditional light source of ultraviolet curing technology has been matured. But because of the light source itself and the limitations of the optical system, the linear light radiation intensity of illumination is low. And the uniformity of the light field is not high enough. This paper provides a design of freeform surface which makes the emergent light of ultraviolet-LED becoming a linear light source effectively. The SolidWorks software is used to design initial structure of the lens. And then the structure is imported into LightTools software to simulate the light. The light is optimized by establishing the objective function and changing the parameters, so that the emergent light can present high brightness and high linear light evenness..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1222003 (2014)
Design of a High Resolution and Wide Field Space Infrared Optical System
Mei Gui, Zhai Yan, Miao Jianyu, Li Guangze, and Pu Qianshuai
According to the requirements on high-resolution, wide-field-of-view, all-time reconnaissance and search for maritime targets, a coaxial catadioptric optical system with medium wave infrared (MWIR) is designed. It operates at the orbit altitude of 1200 km with the wavelength spanning from 3.7 μm to 4.8 μm, and it preseAccording to the requirements on high-resolution, wide-field-of-view, all-time reconnaissance and search for maritime targets, a coaxial catadioptric optical system with medium wave infrared (MWIR) is designed. It operates at the orbit altitude of 1200 km with the wavelength spanning from 3.7 μm to 4.8 μm, and it presents the ground resolution of 10 m at nadir. After detailed analysis and calculation, the focal length of this system is 3000 mm, and the relative aperture is 14. The angle of field reaches 14.203°, and the earth area coverage can reach 300 km with scanning former lens group. A focusing mechanism is developed to correct thermal aberrations of the system from 10 ℃ to 30 ℃. The modulation transfer function (MTF) corresponding to the whole field of view (FOV) is larger than 0.39, which can approach diffraction limit at Nyquist frequency of 21 lp/mm. In order to suppress stray radiations, the optical system is optimized to realize 100% cold-shield-match efficiency. The above results show that the properties and structure feasibility of this optical system closely meet the requirements..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1222004 (2014)
Design of Unobscured Three-Mirror Anamorphic Optical Systems
Zhu Hao, Cui Qingfeng, and Piao Mingxu
Anamorphic optical systems have different focal lengths in X and Y direction, objective field of view (FOV) aspect ratio will not be restrained by detector aspect ratio, so it can enlarge the FOV or improve the target resolution in one direction while not affecting another direction. Design method of unobscured three mAnamorphic optical systems have different focal lengths in X and Y direction, objective field of view (FOV) aspect ratio will not be restrained by detector aspect ratio, so it can enlarge the FOV or improve the target resolution in one direction while not affecting another direction. Design method of unobscured three mirror anamorphic optical systems is studied. Zernike aberration analytical method is used to analyze the aberration characteristics. Biconic Zernike surfaces of double curvature is used to correct the aberrations. A cooled mid-wave infrared optical system is designed at focal length in X direction of fx=100 mm, focal length in Y direction of fy=150 mm, F number of 2 with FOV of 3.3°×1.65°. The aspect ratio of the detector is 43 and the aspect ratio of the objective FOV is 21. The modulation transfer function of this system is above 0.61 all over the FOV at the Nyquist frequency of 33 lp/mm. Each reflective surface and the whole system are symmetric about the YZ plane. The result shows that this system can change the aspect ratio in objective FOV and enlarge the FOV in X direction with compact structure and favorable image quality..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1222005 (2014)
Design on Surface Shape of Conicoidal Conformal Optical Domes
Zhang Wang, Wang Dongsheng, Qin Lanqi, Dang Fanyang, Chen Shouqian, and Fan Zhigang
The ellipsoidal domes generate huge air resistance, which limits the operational performance of precise guided weapons. To reduce the air drag, the conicoidal conformal optical domes are investigated and a better surface shape of the dome is designed. The computational fluid dynamics method is adopted to compute the drThe ellipsoidal domes generate huge air resistance, which limits the operational performance of precise guided weapons. To reduce the air drag, the conicoidal conformal optical domes are investigated and a better surface shape of the dome is designed. The computational fluid dynamics method is adopted to compute the drag coefficients produced by the conicoidal conformal optical domes. The evaluation function of the drag coefficient is established. Based on the ray tracing theory, the evaluation function of imaging quality of conformal domes is modeled by putting the average root mean square wavefront errors of different fields of regards to the evaluation parameters. Based on the radar scattering theory, the radar scattering cross sections of conformal domes are computed. The evaluation function of radar scattering property is established. Taking the air resistance, imaging quality and radar scattering property into account, the evaluation function of comprehensive performance of the conicoidal conformal optical domes is established. The parabolic dome with the fineness ratio of 1.5 is proved to possess better comprehensive performance. Compared with the ellipsoidal dome, the parabolic dome established in this paper just produces 2/3 air resistance of the ellipsoidal dome does..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1222006 (2014)
Numerical Simulation of Optical Force on Dielectric Nanosphere by Focused Light Pulse with Finite-Difference Time-Domain Method
Li Hong, Li Rui, Pan Shi, and Zhang Yi
Numerical simulation of the optical force exerted on dielectric nanosphere in laser trapping device with three dimensional finite-difference time-domain (FDTD) method is proposed. The focused light pulse is implemented in FDTD total field zone according to Richards-Wolf vectorial diffraction theory. The monochromatic fNumerical simulation of the optical force exerted on dielectric nanosphere in laser trapping device with three dimensional finite-difference time-domain (FDTD) method is proposed. The focused light pulse is implemented in FDTD total field zone according to Richards-Wolf vectorial diffraction theory. The monochromatic field is extracted from the interacted electromagnetic field between focused light pulse and dielectric nanosphere by discrete Fourier transform, and the results are substituted into Maxwell stress tensor to calculate the optical force. The method is accurated for both simulation of focused light pulse and calculation of optical force because it is based on strict theories. High efficiency can be achieved for using focused light pulse as incident source. The optical force exerted on dielectric nanosphere is calculated when the sphere center is moving in the focal plane and along the axis of the object lens. From the calculation results we can conclude that the high numerical aperture object lens and short wavelength benefit the transverse manipulation of dielectric nanosphere in the focal plane, and high numerical aperture object lens with appropriate wavelength can trap dielectric nanosphere along the axis of the lens..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1222007 (2014)
Optical Devices
A Intensity Modulated Spectro-Polarimetric Analyzer Based on Fourier Transformation
Yuan Yinlin, Zheng Xiaobing, Wu Haoyu, Meng Fangang, Kang Qing, Chen Ligang, Li Jianjun, and Zou Peng
For high-precision measurement of target polarization information, a high-precision spectro-polarimetric analyzer is developed, which combines existing high-precision standard detectors technology with polarization detecting theory. By continuous and equiangular rotation of the polarizer, Fourier progression algorithm For high-precision measurement of target polarization information, a high-precision spectro-polarimetric analyzer is developed, which combines existing high-precision standard detectors technology with polarization detecting theory. By continuous and equiangular rotation of the polarizer, Fourier progression algorithm is used to calculate degree of polarization and it can greatly reduce uncertainty caused by angular error of polarizer. Optimum design of main optical path and fine linear standard trap detector with large dynamic range ensures the measurement precision. A set of alternate narrow-band filters are used to achieve degree of polarization measurement of continuous spectrum. The test results show that the degree of polarization is from 0.1 to 0.99, and the measurement uncertainty of spectro-polarimetric analyzer is below 0.15%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1223001 (2014)
Influence of Attitude Variation on the Detection Ability of Satellite Photoelectric Imaging System
Yang Lu, Niu Yanxiong, Lü Jianming, Zhang Ying, Liu Wenwen, Li Jianping, and Niu Haisha
In order to study the influence of satellite attitude variation on the detection ability of the satellite photoelectric imaging system, the targets in 0.38~0.78 μm spectrum of visible light radiation are calculated. The visible light reflectance model of the space-based optical observation is established on the basis oIn order to study the influence of satellite attitude variation on the detection ability of the satellite photoelectric imaging system, the targets in 0.38~0.78 μm spectrum of visible light radiation are calculated. The visible light reflectance model of the space-based optical observation is established on the basis of basic radiation theory. According to the geometric structure and material properties of the target, the influence of attitude variation on the area of effective incident section is analyzed. The formulas of the signal-to-noise ratio (SNR) and detection distance are derived, the influence of attitude variation on the detection capability is numerically simulated. The calculation results indicate that when the attitude changes over a period of time, to the 2.2 m×2.7 m solar panel, the maximum difference of SNR and detection distance can reach 101 and 105 km respectively with strong directionality, and to the satellite with 12 m high and 4 m diameter, the maximum difference can reach 102 and 106 km respectively. Attitude variation has a significant impact on the detection ability..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1223002 (2014)
Study on Detection of Greenhouse Gases Based on Quantum Cascade Laser
Wei Min, Liu Jianguo, Kan Ruifeng, Wang Wei, Yao Lu, Xu Zhenyu, Yuan Song, Dai Yunhai, and Jia Liangquan
The mid-infrared spectrum region, which corresponds to the fundamental absorption of molecules, can be applied to high-sensitivity trace gas measurement. A method using a mid-infrared continuous-wave quantum cascade laser (CW-QCL) operated in room temperature with wavelength modulation spectroscope (WMS) is demonstrateThe mid-infrared spectrum region, which corresponds to the fundamental absorption of molecules, can be applied to high-sensitivity trace gas measurement. A method using a mid-infrared continuous-wave quantum cascade laser (CW-QCL) operated in room temperature with wavelength modulation spectroscope (WMS) is demonstrated. A method of eliminating influence of cross interference between different gases is studied and related verification experiment is performed. An open path greenhouse gas detection system using a quantum cascade laser with central wavelength around 1274 cm-1 is constructed and utilized to monitor CH4 and N2O in atmsphere simultaneously with a 101 m open optical path measurement test, which achieves detection limits of 3.87×10-9 and 1.28×10-9 respectively. The feasibility of the experiment system and the method is verified, which lays a foundation for high-sensitivity detection of greenhouse gases in regional environment..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1230003 (2014)
Physical Optics
Study on High-Numerical-Aperture-Focused Characteristics of Vector Beam Produced by π Phase Plate
Chen Guojun, Zhou Qiaoqiao, Ji Xianming, and Yin Jianping
Linear polarized light is converted to radial and angular vector hollow beams by using Mach-Zehnder interferometer light path with π phase plate. The distribution of the electromagnetic field focused with high numerical aperture is calculated by employing the Richards-Wolf classical vector diffraction model. The resultLinear polarized light is converted to radial and angular vector hollow beams by using Mach-Zehnder interferometer light path with π phase plate. The distribution of the electromagnetic field focused with high numerical aperture is calculated by employing the Richards-Wolf classical vector diffraction model. The results show that the maximum intensity and intensity gradient of the axisymmetric vector hollow beam can respectively reach the magnitude of 1011 W·m-2 and 1017 W·m-3 under the illumination of laser with the power of 10-3 W magnitude, and the radius of the dark spot is only 0.24λ. Meanwhile, strong distributions of the longitudinal electric and magnetic fields are produced. The density distribution of the local photon orbital angular momentum can be adjusted by regulating the optical path difference of the interferometer. Therefore, this beam has good application prospect in atomic optics..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1226001 (2014)
Remote Sensing and Sensors
Deformable Mirror Eigen Modes Based Wavefront Error Correction Method Used for Space Optical Remote Sensor
Yu Ji, and Dong Bing
An adaptive optics wavefront error correction method based on deformable mirror (DM) eigen modes is proposed for high-resolution space optical remote sensors. The influence functions of DM actuators are used to obtain a set of DM eigen modes whose derivatives are orthogonal with each other. The integration of image powAn adaptive optics wavefront error correction method based on deformable mirror (DM) eigen modes is proposed for high-resolution space optical remote sensors. The influence functions of DM actuators are used to obtain a set of DM eigen modes whose derivatives are orthogonal with each other. The integration of image power spectrum at low spacial frequence area is used as merit function. The required correction amount of each mode is directly solved from the relationship between eigen-mode coefficients and the merit function. The eigen modes are obtained from the 37-channel DM. The correction accuracy of Zernike aberrations is discussed by simulation in open-loop and closed-loop modes. The effect of phase bias and spatial frequency range of image on correction accuracy is analyzed quantitatively. The simulation result of thermal deformations of the primary mirror of optical remote sensor is provided. The influence of image noise and different remote images on the method is discussed. The simulation results show that the method effectively corrects wavefront errors. With the advantage of fast convergence speed and insensitivity to image noise and image content, the DM eigen modes based wavefront error correction method is appropriate for space optical remote sensors..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1228001 (2014)
A Novel Algorithm Based on Triangulated Irregular Network for Edge Detection from LiDAR Data
Xuan Hejun, Miao Qiguang, Liu Ruyi, and Guo Xue
The definition of triangle shape variable is provided and a novel algorithm based on triangulated irregular network (TIN) for edge detection from airborne LiDAR data is proposed. The TIN is generated in LiDAR data. Each triangle shape variable of TIN is calculated, and the edge triangle is determined according to the dThe definition of triangle shape variable is provided and a novel algorithm based on triangulated irregular network (TIN) for edge detection from airborne LiDAR data is proposed. The TIN is generated in LiDAR data. Each triangle shape variable of TIN is calculated, and the edge triangle is determined according to the different triangle shape variables. These edge triangles are processed to obtain edge points. In view of the LiDAR with blank data area which may be caused by rivers etc., in which case the edge points can not be detected only by the triangle shape variable, using the sum of the quadratic distance from the three vertices to the center of gravity as a measure to determine the skinny triangle is put forward. The experimental results show that the proposed algorithm performs well to extract the edge points and obtain the edge information from the LiDAR data..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1228002 (2014)
Two-Dimensional Matched Filtering Imaging Algorithm for Synthetic Aperture Imaging Ladar
Sun Zhiwei, Hou Peipei, Zhi Yanan, Sun Jianfeng, Xu Qian, Zhou Yu, and Liu Liren
A two-dimensional (2D) matched filtering imaging algorithm for synthetic aperture imaging ladar (SAIL) is proposed. This algorithm simultaneously performs quadratic phase matched filtering in range and azimuth direction for the data obtained through heterodyne detection with single frequency local oscillator and linearA two-dimensional (2D) matched filtering imaging algorithm for synthetic aperture imaging ladar (SAIL) is proposed. This algorithm simultaneously performs quadratic phase matched filtering in range and azimuth direction for the data obtained through heterodyne detection with single frequency local oscillator and linear frequency modulation signal light to achieve target image. The SAIL 2D data-collection equation of point target through heterodyne detection with single frequency local oscillator is presented. Imaging process of the algorithm is mathematically analyzed. Imaging resolutions of the algorithm for the SAIL with rectangular and circular apertures are described specificly. Imaging result of simulated SAIL echo data is presented..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1228003 (2014)
Spectroscopy
Electrowetting-Based Liquid Prism
Zhao Rui, Tian Zhiqiang, Liu Qichao, Wang Ping, and Liang Zhongcheng
A liquid micro-optical prism based on electrowetting is developed for wide angle beam tracking and steering. The shape of the two liquid interfaces is analyzed, the relationship between contact angle and two voltages is derived, and the deflection of the beam from the system is detected. In the meantime, COMSOL softwarA liquid micro-optical prism based on electrowetting is developed for wide angle beam tracking and steering. The shape of the two liquid interfaces is analyzed, the relationship between contact angle and two voltages is derived, and the deflection of the beam from the system is detected. In the meantime, COMSOL software is employed to analyze the effect of dynamic viscosity on the prism′s response time and stability. The results indicate that the contact angle between the conductive fluid and wall changes, then interface of the immiscible liquids is rendered into plane accordingly when different voltages are applied on the wall. It succeeds in controlling beam tracking and steering as traditional optical prism. Due to electrowetting saturation, the maximum deflection of the liquid prism approaches to 20° (-10°~+10°); If the electrowetting saturation is decreased or even eliminated while ratio of the refractive indexes of two liquids is increased, the ability of deflection of the system will be enhanced largely. To achieve stable performance and stability of the prism, the optimal dynamic viscosity should be 0.03 Pa·s..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1223003 (2014)
Study on Analyzing Active Ingredient of Marasmius androsaceus via Radial Basis Function Neural Network Combining with Near Infrared Spectroscopy
Song Jia, Li Chenliang, Xing Gaoyang, Meng Qingfan, Lu Jiahui, Cao Jiaming, Zhou Yulin, Wang Di, and Teng Lirong
Radial basis function neural network (RBFNN) combining with near infrared spectroscopy (NIRS) is applied to develop quantitative analyzing models of mannitol, polysaccharide and adenosine in Marasmius androsaceus fermentation mycelium. Using submerge fermentation, 164 Marasmius androsaceus mycelium samples are obtainedRadial basis function neural network (RBFNN) combining with near infrared spectroscopy (NIRS) is applied to develop quantitative analyzing models of mannitol, polysaccharide and adenosine in Marasmius androsaceus fermentation mycelium. Using submerge fermentation, 164 Marasmius androsaceus mycelium samples are obtained. The contents of mannitol, polysaccharide and adenosine are determined via traditional methods and the near infrared spectroscopy data of the 164 samples are collected. The outliers are removed and the number of calibration set is confirmed via Monte Carlo partial least square (MCPLS) method. Based on the values of degree of approach (Da), the moving window radial basis function neural network (MWRBFNN) is applied to optimize characteristic wavelength variables, pre-processing methods, hidden layer nodes (NH) and spreads in the models. The quantitative analyzing models of mannitol, polysaccharide and adenosine in Marasmius androsaceus fermentation mycelium are developed successfully. The correlation coefficients between the reference values and predictive values of mannitol, polysaccharide and adenosine in both of the calibration set and validation set of optimum RBFNN-NIRS models are 0.9274, 0.9009, 0.9440 and 0.9354, 0.9018, 0.8847 respectively. All the data suggest that these models possess excellent fitness and predictive ability..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1230001 (2014)
Theoretical Investigation of Electron Transport Properties for Firefly Keto-Form Oxyluciferin Derivatives
Min Chungang, Leng Yan, Yang Xikun, Huang Shaojun, Wang Shaohua, and Ren Aimin
The density functional theory (DFT) with the MPW3PBE functionality is used to optimize the firefly keto-form oxyluciferin with the substitution of methyl, methoxy, cyano, fluoride, amino and nitro groups. Based on the optimized molecular structures, the ionization potentials (IP), electron affinities (EA), hole extractThe density functional theory (DFT) with the MPW3PBE functionality is used to optimize the firefly keto-form oxyluciferin with the substitution of methyl, methoxy, cyano, fluoride, amino and nitro groups. Based on the optimized molecular structures, the ionization potentials (IP), electron affinities (EA), hole extraction potentials (HEP), electron extraction potentials (EEP), as well as the hole and electron reorganization energy (λ) are calculated to investigate the hole and electron transport properties. The electronic absorption spectra, the lowest excited singlet state S1 and the fluorescence spectra of firefly keto-form oxyluciferin derivatives are calculated by the time dependent density functional theory (TDDFT) MPW3PBE/6-31+G(d) method. The results show that KNH2 can be used as hole-transport materials, KNO2, KCN, KF, KOCH3, KNH2 and KCH3 can be used as electron transport materials..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1230002 (2014)
Ultrafast Optics
Femtoseoncd Laser-Induced Ablation Regimes and Thresholds in a Nickel-Based Superalloy
Zhang Wei, Feng Qiang, Cheng Guanghua, and Zhang Xiaobing
Femtosecond laser-induced ablation regimes and ablation thresholds of single-crystal nickel-based superalloy are investigated by means of microstructure on machined surface and trench as a function of laser fluence of 0~12.8 J/cm2 and the number of pulses of 0~8000. Two distinct ablation regimes (no-melting and meltingFemtosecond laser-induced ablation regimes and ablation thresholds of single-crystal nickel-based superalloy are investigated by means of microstructure on machined surface and trench as a function of laser fluence of 0~12.8 J/cm2 and the number of pulses of 0~8000. Two distinct ablation regimes (no-melting and melting ablation regime) are observed, dependent on the incident laser fluence. The ablation threshold fluences for these two ablation regimes are determined to be 0.23 J/cm2 and 1.21 J/cm2 in the superalloy. And the incubation factors for these two ablation regimes are determined to be 0.90 and 0.92. Furthermore, the relationship between both ablation regimes and ablation thresholds and their parametric dependence is established. The experimental results have practical guiding for processing nickel-based aviation of no recast layer and micro-cracks..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1232001 (2014)
Study on Writing of Double Line Waveguide in Yb:YAG with Ultrafast Laser
Tang Wenlong, Song Qiongge, Xu Qing′an, Liu Xin, and Cheng Guanghua
The writing of double line waveguide in Yb3+ doped yttrium aluminum garnet (Yb:YAG) crystal is studied by using titanium sapphire laser with the pulse width of 160 fs, central wavelength of 775 nm and repetition frequency of 50 kHz. The phenomenon of polarization guiding is discovered in the waveguide. The laser with pThe writing of double line waveguide in Yb3+ doped yttrium aluminum garnet (Yb:YAG) crystal is studied by using titanium sapphire laser with the pulse width of 160 fs, central wavelength of 775 nm and repetition frequency of 50 kHz. The phenomenon of polarization guiding is discovered in the waveguide. The laser with polarization parallel to the direction of double line can be guided, but the laser with polarization perpendicular to the direction of double line cannot be guided. The effects of written parameters, such as double line separation, laser pulse energy and writing speed, on the formation of the waveguide are analyzed. Experimental results show that the waveguide has the good property of guiding under the writing conditions of double line separation of 30 μm, writing speed of 400 μm/s and pulse energy of 5.0 μJ. Bivariate distribution of the waveguide refractive index is reconstructed by near-field mode and the maximum refractive index change is 1.8×10-4. A continuous waveguide laser with a wavelength of 1030.5 nm is obtained and the output power is 4.7 mW..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 12, 1232002 (2014)
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