Contents
2015
Volume: 35 Issue s1
68 Article(s)
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Research Article
Analysis and Optimization of GaAs/AlGaAs Optical Phased Array
Sun Yanling, and Chen Jingye
The optical phased array consisting of multilevel GaAs/AlGaAs waveguides is analyzed in simulation and experiment. With the help of a novel photon design and simulation software,the finite element method and 2.5-dimensional finite-different time-domain (FDTD) are used to simulate the electrical and optical properties oThe optical phased array consisting of multilevel GaAs/AlGaAs waveguides is analyzed in simulation and experiment. With the help of a novel photon design and simulation software,the finite element method and 2.5-dimensional finite-different time-domain (FDTD) are used to simulate the electrical and optical properties of the device respectively. The results indicate that the built-in electric field of the waveguide core has an influence on the total electric field and the property of emerging beam. The built-in electric field is up to 2.53×106 V/m with the p-i-n structure. The phase modulation is up to 2π with a reversed bias voltage (-10 V) applied to the device with 2416 μm long. Basing on single-mode structure, the coupling effect between adjacent cores is also taken into consideration. The influence of refractive index difference on the coupling length is also demonstrated and the proper effective index difference of 0.1 is given..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 125001 (2015)
Dispersion effect on Ultrashort Airy Pulse Propagation
Zhao Han, Song Zhenming, and Lin Yuxian
The Airy pulse dispersion effect by the split-step Fourier transform method (SSFM) is sumulated and analyzed. The wave transmission characteristic of Airy pulse under second and third-order dispersion effects in temporal domain is discussed. Furthermore, the influence of the initial chirp and weakly nonlinear effects iThe Airy pulse dispersion effect by the split-step Fourier transform method (SSFM) is sumulated and analyzed. The wave transmission characteristic of Airy pulse under second and third-order dispersion effects in temporal domain is discussed. Furthermore, the influence of the initial chirp and weakly nonlinear effects is studied. The results show that the positive third-order dispersion effect leads to pulse compression and amplitude increase. On the other hand, the negative third-order dispersion effects leads to pulse broadening and amplitude decrease. When taking the effect of the initial chirp and weakly nonlinear effects into account. It is found that as the third-order dispersion effects growing, the quality of Airy pulse reduces..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 132001 (2015)
[in Chinese]
Coherent Doppler Lidar Observations of Marine Atmospheric Boundary Layer Height in the Bohai and Yellow Sea
Wang Dongxiang, Song Xiaoquan, Feng Changzhong, Wang Xitao, and Wu Songhua
During the National Natural Science Foundation of China open cruise of the R/V Dongfanghong-2 (NSFC 41349901), coherent Doppler lidar developed by Ocean University of China is used to observe atmospheric boundary layer structure in the Bohai and Yellow Sea. Lidar measurement is operated in the region between 32oN～40oN During the National Natural Science Foundation of China open cruise of the R/V Dongfanghong-2 (NSFC 41349901), coherent Doppler lidar developed by Ocean University of China is used to observe atmospheric boundary layer structure in the Bohai and Yellow Sea. Lidar measurement is operated in the region between 32oN～40oN and 118.5oE～125.3oE, from April 27 to May 19, 2014. Lidar transmits the laser pulse to the atmosphere and receives its backscattering echo signals. Signal to noise ratio is calculated for each range bin of fast Fourier transform spectrum. The marine atmospheric boundary layer height is retrieved according to the minimum of gradient of signal to noise ratio profile. Comparisons between coherent Doppler lidar retrieval and synchronous radiosonde profiling, Vaisala CL31 laser ceilometer data show a good agreement between each other. Correlation of lidar results with radiosonde potentail temperature data is 79% with a standard deviation of 610 m. Correlation of lidar and radiosonde relative humidity data is 90% with a standard deviation of 370 m. And the correlation of lidar and ceilometer data is 94% with a standard deviation of 320 m..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 101001 (2015)
Spatial Coherence of Partially Coherent Annular Beams in Oceanic Turbulence
Pu Huan, Ji Xiaoling, and Yang Ting
Based on the extended Huygens-Fresnel principle, the analytical expression for the coherence degree of partially coherent annular beams propagating through oceanic turbulence is derived. The changes of the coherence degree and the width of the coherence degree of partially coherent annular beams versus the propagation Based on the extended Huygens-Fresnel principle, the analytical expression for the coherence degree of partially coherent annular beams propagating through oceanic turbulence is derived. The changes of the coherence degree and the width of the coherence degree of partially coherent annular beams versus the propagation distance, the oceanic turbulence parameters and the beam parameters are investigated in detail. It is shown that the oscillatory behavior of the coherence degree may appear with partially coherent annular beams propagating in free space or weak oceanic turbulence, but the coherence degree takes a Gaussian-like profile as the strength of oceanic turbulence increases. On the other hand, under weak oceanic turbulence condition, the width of the coherence degree reaches a maximum at a certain propagation distance, which depends on the obscure ratio and the correlation parameter of annular beams. However, under strong oceanic turbulence condition, the coherence degree is nearly independent of the obscure ratio and the correlation parameter of annular beams. The results are useful for applications of partially coherent annular beams in oceanic turbulence..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 101002 (2015)
Comparison of Refractive Index Structure Constant Deduced from Angle of Arrival Fluctuation and Scintillation Effects
Song Lujun, Ni Xiaolong, Liu Yi, and Liu Zhi
With the purpose of comparing the differences of reflective index structure constant measured from angle of arrival and from scintillation effects, an experiment of laser propagation in atmosphere is conducted at a distance of 890 meters in the horizontal path. Scintillation index and variance of angle of arrival fluctWith the purpose of comparing the differences of reflective index structure constant measured from angle of arrival and from scintillation effects, an experiment of laser propagation in atmosphere is conducted at a distance of 890 meters in the horizontal path. Scintillation index and variance of angle of arrival fluctuations are applied respectively to deduce the refractive-index structure constant in weak turbulence. The measurement results indicate that there are some differences between the two results, but the overall trends remain the same. The reason for the differences is analyzed quantitatively from two perspectives: the frequency response characteristic of refractive index fluctuation and the effect of the change of inner and outer scales on measuring. The simulation results show that scintillation is more easily affected by large scale turbulent vortexes, but angle of arrival （AOA） fluctuation is more sensitive to small turbulent vortexes. The change of inner scale has a greater influence on the result of scintillation measuring; while the change of outer scale has a larger effect on the result of the arrival-angle fluctuations measuring. The result of the arrival-angle fluctuation measuring reflects the change of large scale turbulent fields, while the result of scintillation measuring reflects small scale turbulent fields..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 101003 (2015)
Characteristic Analysis of Hot Air Convection Atmospheric Turbulence simulator
Ni Xiaolong, Song Lujun, Fu Qiang, Liu Yi, Li Xiaowei, Jiang Huilin, and Liu Zhi
As one of most important atmospheric turbulence simulator, hot air convection atmospheric turbulence simulator has been widely used in many areas. It can simulate scintillation, phase fluctuations, angle-of-arrival, beam expander and beam wander caused by atmospheric turbulence. 532, 808, 1064, 1550 nm lasers transmitiAs one of most important atmospheric turbulence simulator, hot air convection atmospheric turbulence simulator has been widely used in many areas. It can simulate scintillation, phase fluctuations, angle-of-arrival, beam expander and beam wander caused by atmospheric turbulence. 532, 808, 1064, 1550 nm lasers transmiting, receiving and measuring device have been used to calibrate the coherence length, refractive index structure constant, equivalent scintillation index,and the spectral characteristics and probability density distribution characteristics of the scintillation and the angle-of-arrival. Experimental results show that the range of atmospheric turbulence coherence length obtained by atmospheric turbulence simulator is 5~20 cm. The maximum C2n simulated by this simulator is 1.81×10-16 when equivalent turbulence link length is 1 km. The maximum C2n is 1.81×10-15when equivalent turbulence link length is 10 km, and the equivalent distance of scintillation index is 661.2 m. Besides, the spectral characteristics and probability density distribution characteristics of scintillation index and angle-of-arrival are similar to the real atmospheric turbulence. In summary, the atmospheric turbulence simulated by the hot air convection turbulence simulator is close to the real atmosphere..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 101004 (2015)
Distance for Conservation of Topological Charge in Atmospheric Turbulence
Zeng Jun, and Li Jinhong
Based on the non-Kolmogorov spectrum and the generalized Huygens-Fresnel principle, taking the cosh-Gaussian (ChG) vortex beams as a typical example, the distance for the conservation of topological charge of partially coherent ChG vortex beams propagating through non-Kolmogorov atmospheric turbulence is studied. With Based on the non-Kolmogorov spectrum and the generalized Huygens-Fresnel principle, taking the cosh-Gaussian (ChG) vortex beams as a typical example, the distance for the conservation of topological charge of partially coherent ChG vortex beams propagating through non-Kolmogorov atmospheric turbulence is studied. With the increment of general structure constant C～2n and the waist width w0, as well as the decrement of the general exponent α, the inner scale l0 and spatial correlation length σ0, the distance for the conservation of topological charge will decrease , whereas outer scale L0 and part parameters of hyperbolic cosine Ω0 has no effect on the distance for the conservation of topological charge..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 101005 (2015)
Effects of Atmospheric Turbulence on the Aperture Averaging Factor of the Gaussian-Schell Model Beams
Lu Fang, Zhao Dan, and Han Xiang′e
The performance of wireless laser communication can be affected due to atmospheric turbulence and the aperture averaging can effectively inhibit scintillation caused by turbulence. The aperture averaging factor of scintillation for Gaussian-Schell mode (GSM) beams is derived according to the expression of aperture averThe performance of wireless laser communication can be affected due to atmospheric turbulence and the aperture averaging can effectively inhibit scintillation caused by turbulence. The aperture averaging factor of scintillation for Gaussian-Schell mode (GSM) beams is derived according to the expression of aperture averaging factor given by Tatarskii and the relationship between mutual coherent function and cross-spectral density function for narrow-band wavefield. The effects of coherent parameter of the source,the strength of turbulence, inner scale and outer scale of the turbulence on the aperture averaging factor of scintillation for GSM beams are discussed. It is shown that the effects of the coherent parameter on the aperture averaging factor become smaller with the turbulence increase. The aperture averaging factor reaches saturated more quickly with stronger turbulence, and further increasing of the aperture of receiver becomes no longer valid in reduction of scintillation. The inner scale of turbulence has a significant effect on aperture averaging factor，while the influence of outer scale can be neglected. The inner scale of turbulence plays an important part in analysis of scintillation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 101006 (2015)
High-Resolution Retinal Imaging Based on Reset of Control Signals Algorithm
Xiao Fei, Zhao Junlei, Zhao Haoxin, Dai Yun, and Zhang Yudong
For ocular adaptive optics systems, there is no necessary to calculate Zernike mode coefficients during iterations. A modified algorithm based on reset of control signals is proposed. The modified algorithm is more suitable for ocular adaptive optics because both calculating time and storage space are saved. After prinFor ocular adaptive optics systems, there is no necessary to calculate Zernike mode coefficients during iterations. A modified algorithm based on reset of control signals is proposed. The modified algorithm is more suitable for ocular adaptive optics because both calculating time and storage space are saved. After principle description and computer simulation, the algorithm is tested on a retinal imaging system which is based on dual deformable mirrors. The two deformable mirror are controlled fast and stably. High resolution retinal images are acquired. Both simulation and experimental results indicate that this algorithm can effectively compensate for phase distortions and significantly suppress the coupling between two deformable mirrors..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 101007 (2015)
Atomic and Molecular Physics
Experiment Study on Optical Lattice Clock of Strontium at NTSC
Tian Xiao, Xu Qinfang, Yin Mojuan, Kong Dehuan, Wang Yebing, Lu Benquan, Liu Hui, Ren Jie, and Chang Hong
The accuracy and stability of optical clocks has achieved 10-18 level currently. The progress on the optical lattice clocks of Strontium (Sr) atoms at National Time Service Center is presented. 88Sr，which has the highest natural abundance in four isotopes of Sr, is cooled on the basis of transitions (5s5s)1S0—(5s5p)1P1The accuracy and stability of optical clocks has achieved 10-18 level currently. The progress on the optical lattice clocks of Strontium (Sr) atoms at National Time Service Center is presented. 88Sr，which has the highest natural abundance in four isotopes of Sr, is cooled on the basis of transitions (5s5s)1S0—(5s5p)1P1 and (5s5s)1S0—(5s5p)3P1. In order to cancel the effect of Doppler shift and recoil shift these cold atoms are trapped in the optical lattice. However, the optical lattice where atoms are trapped can make the energy level shift, called A. C. Stark shift. The “magic” wavelength for clock transition (5s5s)1S0—(5s5p)3P0 can make the same Stark light-shift for both of them, being value 813.4 nm. Then those cold 88Sr atoms are confined in a 1-D optical lattice constituted by the laser outputting from an amplified diode laser, operating on the “magic” wavelength 813nm. Consequently, the lifetime of atoms in 1-D optical lattice is measured and the value is 270 ms. The temperature and the number are about 3.5 μK and 1.2×105 respectively. Atoms confined in the optical lattice can provide a long interrogation time for probing the clock transition, furthermore make the foundation for developing the optical lattice clock of Sr atoms..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 102001 (2015)
High Contrast Atomic Clock Signal Based on Coherent Population Trapping
Wang Xin, Zhao Wenyu, Xue Wenxiang, Yu Zhijian, Du Zhijing, Tian Xiao, and Zhang Shougang
An experimental investigation of the coherent population trapping (CPT) resonance excited on the D1 line of 87Rb atoms by bichromatic parallel linearly polarized laser light is presented. The experimental results show that a lin‖lin transition scheme is a promising alternative to the conventional circular-circular tranAn experimental investigation of the coherent population trapping (CPT) resonance excited on the D1 line of 87Rb atoms by bichromatic parallel linearly polarized laser light is presented. The experimental results show that a lin‖lin transition scheme is a promising alternative to the conventional circular-circular transition scheme for an atomic clock. Compared with the circular light transition scheme, linear light accounts for high-contrast transmission resonances, which makes this excitation scheme promising for CPT atomic clock..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 102002 (2015)
Detectors
Pixellated CdZnTe Detector Based Investigation for Non-Linear Variation of Screening Effect Caused by Accumulated Carriers
Li Miao, Xiao Shali, Yang Guoqiang, and Ma Yuedong
With different X-ray tube voltages the imaging screening effect of the pixellated CdZnTe detector is investigated under the ultrahigh irradiance. Moreover, a novel fluctuation process of the screening effect has been observed. Measurement results reveal that event counts of pixels which are distributed at the edge of tWith different X-ray tube voltages the imaging screening effect of the pixellated CdZnTe detector is investigated under the ultrahigh irradiance. Moreover, a novel fluctuation process of the screening effect has been observed. Measurement results reveal that event counts of pixels which are distributed at the edge of the irradiated area experience a sudden increase followed by a continuous decrease when the tube voltage rises from 15 kV to 45 kV. Based on the Poisson equation, a theoretical model of the CdZnTe detector solved by the finite element method is developed which enables the penetrating investigation of the carrier collection in the CdZnTe crystal. A comparison between model simulations and test results shows that pixels in the central irradiated area are completely screened under increasing incident photon energy and linearity attenuation parameter. This is because the emergence of the relatively higher potential region, which is caused by the increasing of incident photon energy and linearity attenuation parameter, leads to the twist of the electron drift way. Furthermore, with the increase of the incident photon energy, the inconsecutive expansion of the accumulated carrier scope results in the fluctuation of the event counts of pixels distributed around the screening area. The imaging results deduced from the simulations are well consistent with the experimental data..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 104001 (2015)
Diffraction and Gratings
Substrate Positioning Error Analysis and Compensation Method in Holographic Grating Fabrication
Dong Ningning, Cui Jinjiang, Xu Jiangen, and Xu Jie
Substrate positioning error in exposure system will directly harm the groove accuracy of holographic grating. It will cause grating period error in the plane holographic grating, or increase the aberration of the concave holographic grating. The effects on grating period with the positioning error of the standard gratiSubstrate positioning error in exposure system will directly harm the groove accuracy of holographic grating. It will cause grating period error in the plane holographic grating, or increase the aberration of the concave holographic grating. The effects on grating period with the positioning error of the standard grating as well as the substrate are analyzed, while moiré fringe method is used to adjust the interference field period in the Lloyd′s mirror interference system of holographic grating. The positioning error which can be compensated by adjusting the substrate parallel to the standard grating surface is pointed out..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 105001 (2015)
Fiber Optics and Optical Communications
Study on Propagation Characteristics of Optical Vortices in Bent Fibers
Sun Xibo, Geng Yuanchao, Liu Lanqin, Zhu Qihua, Huang Zhihua, Huang Wanqing, Zhang Ying, and Wang Wenyi
The propagation characteristics of optical vortices in fibers are studied. The wave equations in the optical waveguide based on the Maxwell′s equation are derived, and then the eigen modes of the step index fiber are solved. According to the relationship of the orbital angular momentum (OAM) and linear polarization (LPThe propagation characteristics of optical vortices in fibers are studied. The wave equations in the optical waveguide based on the Maxwell′s equation are derived, and then the eigen modes of the step index fiber are solved. According to the relationship of the orbital angular momentum (OAM) and linear polarization (LP) modes with the vector modes， the distributions of optical vortices and linear polarization modes in fibers are solved and the advantage of optical vortices in fibers over the LP modes in theory are analyzed. The propagation of the optical vortices in bend fibers is simulated. It is found that the distribution of the optical field has periodic rotating properties. The effects of the fiber′s bending radius and the topological charge on the propagation of optical vortices are researched. The smaller the bending radius is, the greater loss in propagation is produced. The larger the topological charge is, the greater loss in propagation and the shorter rotating period is..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 106001 (2015)
Design and Study on Characteristics of Double-Clad Photonic Crystal Fibers with Flattened Dispersion
Lei Jingli, Li Xiaoxiao, Wang Daobin, Wu Gang, Liu Yanjun, and Hou Shanglin
A double cladding photonic crystal fiber with hexagonal air hole lattice, whose claddings are made by two different sizes of air holes, is designed and the influence of the geometric parameters on its dispersion and low dispersion bandwidth are investigated. The results show that the dispersion, low dispersion bandwidtA double cladding photonic crystal fiber with hexagonal air hole lattice, whose claddings are made by two different sizes of air holes, is designed and the influence of the geometric parameters on its dispersion and low dispersion bandwidth are investigated. The results show that the dispersion, low dispersion bandwidth and the nonlinearity are easily tailored by adjusting the two different sizes of air holes in the cladding as well as the pitch. The near-zero dispersion of (0±1.8) ps·km-1·nm-1 at C and L band can be obtained by optimizing design..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 106002 (2015)
Measurement of Magnetic Field Based on Optical Fiber Evanescent Wave Sensor
Shen Tao, Feng Yue, Dai Hailong, Hu Chao, Xiu Hanjiang, and Wei Xinlao
A new approach is proposed to measure the magnetic field intensity via optical absorption method with optical fiber evanescent wave sensor. A standard single-mode optical fiber used for communication is put into the magnetic field with magnetic fluid and its extramural cladding is local corrupted close to the fiber corA new approach is proposed to measure the magnetic field intensity via optical absorption method with optical fiber evanescent wave sensor. A standard single-mode optical fiber used for communication is put into the magnetic field with magnetic fluid and its extramural cladding is local corrupted close to the fiber core. The evanescent wave of the fiber surface is effected by the change of magnetic field, when the absorb peak is used as detection wavelength The change of magnetic field can be obtained by measuring the optical output intensity of the fiber. The experimental results show that there is a linear relationship between the transmitted intensity and magnetic intensity, the magnetic fluid in the concentration range of 40~110 mT, the detection sensitivity respectively are 0.0019 μW/mT and 0.02 μW/mT of 50 μm and 35 μm for the length is 15 cm. The obtained results have instructive function for resistance to interference and easy to implement of optical fiber magnetic field sensor..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 106003 (2015)
A Multi-Function Integrated Flow Sensing Technology Based on FBG
Liu Chuntong, Li Hongcai, Feng Yongbao, Cai Wei, Zhao Xiaofeng, and Yang Zhiyong
In view of the problems such as the low measurement accuracy, single measuring parameter, large sensor volume are exist in the traditional flow measurement, and a multifunction integrated flow sensor based on fiber Bragg grating (FBG) is designed. The multifunction flow measurement using FBG differential pressure type In view of the problems such as the low measurement accuracy, single measuring parameter, large sensor volume are exist in the traditional flow measurement, and a multifunction integrated flow sensor based on fiber Bragg grating (FBG) is designed. The multifunction flow measurement using FBG differential pressure type flow measurement as structure body, and integrating FBG temperature and pressure sensor, thus the fluid flow, pressure and temperature are measured at the same time. On the base of introducting the FBG sensing principle, the capillary tube packaging FBG sensor and the blind-piple FBG pressure sensor working principle are analyzed. Meanwhile, on the basis of analysis the sensing principle of differential pressure type FBG flow sensor, the structure and realize principles of the multifunction FBG flow sensor are introducted. Using water bath, pressure gauge calibration meter and integrated flow test plantform, which test the sensing charactors of the FBG temperature, pressure and flow sensor within the multifunction FBG sensor. According to the test results, the sensitivity of FBG temperature sensor is 0.015 nm/℃, the sensitivity of FBG pressure sensor is 0.028 nm/MPa, and the sensitivity of FBG flow sensor is 0.068 L/s. At the same time, the temperature sensor is used as a reference, which can solve the temperature inter-sensitive effect in the FBG pressure and flow measurement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 106004 (2015)
Research of Cascaded Coherent Combining of Fiber Lasers Based on 3-dB Fiber Couplers
Yang Yan, Geng Chao, Li Feng, and Li Xinyang
A new method of cascaded coherent combining of fiber lasers based on 3-dB fiber couplers is proposed. The theoretical model of two-unit coherent combining module based on 3-dB fiber coupler is analyzed, and the effects of light intensity and phase mismatch on coherent combining efficiency are studied. The phase-controlA new method of cascaded coherent combining of fiber lasers based on 3-dB fiber couplers is proposed. The theoretical model of two-unit coherent combining module based on 3-dB fiber coupler is analyzed, and the effects of light intensity and phase mismatch on coherent combining efficiency are studied. The phase-control setup using stochastic-parallel-gradient-descent algorithm is established to investigate the feasibility of the two-unit coherent combining module. As the experimental results show, the average value of the normalized combined intensity increases from 0.50 in open loop to 0.92 in closed loop, the mean square error decreases from 9.27% to 0.062%, and the phase locking and intensity matching are crucial to achieve high and stable effect of the coherent combining. Additionally, an extended cascaded structure of coherent combining of fiber lasers based on two-unit coherent combining module is presented and the simulation of eight-unit structure is performed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 106005 (2015)
Image Processing
Region of Interest Detection Based on Salient Features Clustering for Remote Sensing Images
Lü Xinran, Chen Jie, Zhang Libao, Yang Xuye, and Li Jiayi
The region of interest detection for remote sensing images is usually based on global research and setting up the basis of prior knowledge. The new method called salient region detection based on salient features clusting for remote sensing images is proposed. We use the color information to construct the histograms inThe region of interest detection for remote sensing images is usually based on global research and setting up the basis of prior knowledge. The new method called salient region detection based on salient features clusting for remote sensing images is proposed. We use the color information to construct the histograms in different color channel (RGB) to compute the information maps in each color channel. After fusing the information maps, we can get the single saliency maps. To get the saliency maps in CIELab color space, we adopt the k-means to cluster all the images in the CIELab color space, which makes it possible to reduce the computational complexity by calculating saliency on cluster-level. Then, through studying the integration of single saliency map and CIELab saliency maps, we get the final saliency maps. Finally, we can construct the mask of region of interest according to the final saliency map, which enable us to get the region of interest segmentation. Result shows that compared with existing models, we get more accurate saliency maps without the basis of prior knowledge. This method will be meaningful in further remote sensing image processing..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 110001 (2015)
Multi-Pig Detection and Tracking Method under the Farm Environment
Duan Yuyao, Ma Li, Wang Hui, and Liu Gang
In order to realize the multi-target tracking of pig’s behavior in pigsty complex light situations and shelter among pigs, the traditional multi-object tracking algorithm is improved, and a target tracking system based on computer vision technology is developed. The foreground detection algorithms are improved, and theIn order to realize the multi-target tracking of pig’s behavior in pigsty complex light situations and shelter among pigs, the traditional multi-object tracking algorithm is improved, and a target tracking system based on computer vision technology is developed. The foreground detection algorithms are improved, and the difference images obtained by gray difference, S-channel difference and frame difference are fusion. The color differences and texture similarity between shadow and background are used to eliminate the effect of shadow upon detection. The camshift algorithm is improved to realize the accurate tracking of pig's motor behavior in pigsty. The improved algorithm integrates the initial position and color information of target pigs, and fixes the histogram model. It improves the tracking accuracy. By the experiments of tracking different varieties pigs and tracking under different light situations, the experimental results show that the proposed target detection method can effectively eliminate the influence of the shadow and the experiments verify the stability of the algorithm, the tracking accuracy rate is greater than 85%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 110002 (2015)
Recognition of the Optical Image Based on the Wavelet Space Feature Spectrum Entropy
Chang Liping, Li Jia, Shi Zhaoxia, and Guo Shuqin
To solve the problem that present recognition accuracy of optical image is not high, the method of image feature extraction based on wavelet space feature spectrum entropy is studied deeply. According to the principle of energy is equal before and after the wavelet transform, the matrix of wavelet energy mode is constrTo solve the problem that present recognition accuracy of optical image is not high, the method of image feature extraction based on wavelet space feature spectrum entropy is studied deeply. According to the principle of energy is equal before and after the wavelet transform, the matrix of wavelet energy mode is constructed, and the singular value decomposition is done to the matrix, then the feature spectrum entropy of singular value is as the image feature. At the same time, the back propagation neural network is also used for image recognition. The experimental results show that the proposed image feature extraction method can obtain higher accuracy of image recognition, and the effectiveness of the method is also proved..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 110003 (2015)
Application of Gaussian-Rayleigh Mixture Model in Remote Sensing Image Segmentation
Hou Yimin, Tang Yue, Sun Xiaoxue, and Sui Wenxiu
Among the remote sensing images segmentation methods, Gaussian mixture model (GMM) is the widely used image model. Gaussian-Rayleigh mixture model (GRMM) is proposed, and it may be more suitable for remote sensing image modeling. The difference between classical GMM and GRMM is introduced. The modeling results of GMM aAmong the remote sensing images segmentation methods, Gaussian mixture model (GMM) is the widely used image model. Gaussian-Rayleigh mixture model (GRMM) is proposed, and it may be more suitable for remote sensing image modeling. The difference between classical GMM and GRMM is introduced. The modeling results of GMM and GRMM to the images are compared. The comparison data shows that the GRMM has less distribution errors than the GMM when modeling the images. The entropy-max method is utilized to determine the optimal class number. The Markov random field (MRF) and a new potential function is employed to segment the images. The iterative conditional model (ICM) is used to calculate the maximum posteriori probability. Three remote sensing images are utilized in the experiment, the fitting and segmentation results of GMM and GRMM are compared in the experiment process. The data and segmentation results show that the proposed method is more effective..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 110004 (2015)
Imaging Systems
An Anti-Counterfeiting Technique Based on Three-Dimensional Imaging Employing Micro-Lens Array
Guo Shuji, Cao Axiu, Shi Lifang, Deng Qiling, and Wu Xiangdong
A new method of designing and manufacturing of anti-counterfeiting labels, which based on the three-dimensional imaging technique employing micro-lens array has been proposed. The three-dimensional imaging model is scientifically built. The structure designing and fabrication of the three-dimensional imaging key elemenA new method of designing and manufacturing of anti-counterfeiting labels, which based on the three-dimensional imaging technique employing micro-lens array has been proposed. The three-dimensional imaging model is scientifically built. The structure designing and fabrication of the three-dimensional imaging key elements, the sub-image and micro-lens array, are carried out. According to the three-dimensional image, the three-dimensional imaging structure is designed with 3DMAX, after all of that, the micro structure and high precision micro-lens array of the three-dimensional structure are fabricated by micro machining technology. Finally, the high resolution anti-counterfeiting label is obtained..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 111001 (2015)
Imaging Experimental Study Based on the Width of 532 nm-Laser Target Echo Pulse
Zhou Xin, Sun Jianfeng, Jiang Peng, Xiong Weihua, and Wang Qi
Laser active imaging radar over a wide depth of field and complex-scene target imaging process, because the remote target echo-signal amplitude is smaller, resulting in a lack of effect on the intensity image, and affecting the target detection and recognition rate. Aiming at this problem, the detection of laser echo pLaser active imaging radar over a wide depth of field and complex-scene target imaging process, because the remote target echo-signal amplitude is smaller, resulting in a lack of effect on the intensity image, and affecting the target detection and recognition rate. Aiming at this problem, the detection of laser echo pulse width to generate laser two-dimensional image is put forward, which is called the pulse-width image, and the pulse-width image is used to detect the wide depth of field and far-reaching distance target. Using the streak tube laser imaging radar scan imaging experiments on multiple building group, the intensity image, range image and pulse-width image are obtained respectively. Analysing by statistical data, the results show that the visual effect of the pulse-width image is better than the intensity image, relative to the intensity image, the pulse-width image can clearly show the far-field targets; for different buildings, the average value of echo pulse width are different, and the beam incident angle, target material is closely related with the echo pulse width: white walls of two different-incident angles, the echo pulse-width difference is 2, the pulse-width of glass and the pink wall differ by 4.7, while the target color (white, pink) has little effect on the 532nm echo pulse width, the difference of pulse width is only 0.2. It proves that the pulse-width image can effectively improve the wide depth of field and far-reaching distance target detection rate..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 111002 (2015)
Nondestructive Testing for Bonding Defects in Aerospace Composite Based on Continuous Terahertz Wave
Pan Zhao, Zheng Xiaokang, Wang Yutian, and Wen Yintang
This paper studies the applications of continuous terahertz wave in nondestructive testing for bonding defects in aerospace thermal insulation composite. Aerospace thermal insulation composite and metal substrates are bonded by epoxy resin adhesive as the experimental sample. The adhesive interface is tested by the refThis paper studies the applications of continuous terahertz wave in nondestructive testing for bonding defects in aerospace thermal insulation composite. Aerospace thermal insulation composite and metal substrates are bonded by epoxy resin adhesive as the experimental sample. The adhesive interface is tested by the reflection type frequency modulated continuous terahertz wave testing system and the frequency range is 0.23\~0.32 THz. Tomographic images are obtained by making the terahertz probe focus on the adhesive interface. The size, shape and position of the defect can be judged by the gray value of images which at 0, 1 and 2 mm below the focal plane. In the imaging processing, edge detection is managed with adaptive threshold Canny operator. The adhesive interface between metal substrates and aerospace thermal insulation composite can be tested by applying the method of continuous terahertz imaging and combined with proper image detection technique..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 111003 (2015)
Application Limits of the Strehl Ratio Approximations
Tan Bitao, Chen Lizi, and Chen Hongbin
When imaging performance of optoelectronic systems to observe point targets or laser far-field effects is evaluated, Strehl ratio is usually used as evaluation criteria, and Strehl ratio is often applied in engineering applications. In order to understand the limits of application field and engineering feasibility, stuWhen imaging performance of optoelectronic systems to observe point targets or laser far-field effects is evaluated, Strehl ratio is usually used as evaluation criteria, and Strehl ratio is often applied in engineering applications. In order to understand the limits of application field and engineering feasibility, study on the approximate application limits is done. The three approximation ways are deduced, which can supply theoretical basis for the approximations. According to Strehl ratio theory, its accurate analysis method under actual aberration condition is obtained as well. The comparison is done between the approximations and accurate method from the view of imaging. Results show that when the wavefront phase error is smaller than 0.1 wavelength, the error between first approximation and second approximation with third approximation is smaller than 10%. When the obscuration ratio is 0.3 and relative error of Strehl ratio is less than 10%, the wavefront phase error variance must be less than 0.13 wavelength for the first approximation method, the wavefront phase error variance must be less than 0.1 wavelength for the second approximation method, and the wavefront phase error variance must be less than 0.17 wavelength for the third approximation method. The research can apply Strehl ration approximations under certain relative error conditions, which can provide technical reference for imaging performance or far-field laser effects assessment..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 111004 (2015)
Application of Phase Demodulation Technique in Turbid Medium Imaging
Zhou Libin, Du Xinchao, He Zhengquan, Sun Hao, Yuan Liutong, Zhang Xiaolei, Hu Manli, and Li Yulin
Multiple light scattering caused by turbid medium can distort the propagation of waves, thus the image will become blurred. A novel method called turbid lens imaging (TLI) is adopted to reconstruct this kind of distorted images. In this method, the complex electric field of output light needs to be obtained to calculatMultiple light scattering caused by turbid medium can distort the propagation of waves, thus the image will become blurred. A novel method called turbid lens imaging (TLI) is adopted to reconstruct this kind of distorted images. In this method, the complex electric field of output light needs to be obtained to calculate transfer matrix of turbid medium. Only the intensity information is recorded by CCD, the phase information will be merged in recorded images. As speckle images are generated when the incident light transmits through turbid medium, there will be obvious error in the phase retrieved by using Hilbert transform directly on the interference fringe pattern. In order to eliminate the influence of speckle intensity changes, the distorted wave image, reference beam image, light interference fringe image and background image are recorded respectively. According to the interference theory, interference cosine factor can be computed, and it will retrieve phase of distorted waves more accurately by using Hilbert transform on cosine factor. In the above method, the complex electric field of distorted wave and the transfer matrix of the turbid medium are successfully calculated. It is more accurate as the amplitude is measured directly. For speckle fringe, the calculation results are much more accurate than the Hilbert transform phase demodulation results..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 111005 (2015)
Measuring Method of Virtual Digital Phase Locking for Phase Modulation Laser Doppler Frequency Parameter
Du Jun, Li Shiming, Zhao Weijiang, and Qu Yanchen
The virtual digital phase locking technique based on LabView visual language is proposed to measure the frequency parameter of phase modulation laser Doppler shift measuring method, and investigate it theoretically and experimentally. For preventing the disturbance between the test signal and the reference signal channThe virtual digital phase locking technique based on LabView visual language is proposed to measure the frequency parameter of phase modulation laser Doppler shift measuring method, and investigate it theoretically and experimentally. For preventing the disturbance between the test signal and the reference signal channels and mixed with noise in the process of reference signal transmission, this virtual digital phase locking technique adopts the method of reference signal generated inside. In order to ensure the same frequency between reference signal and test signal for accurate frequency parameter measurements, the virtual digital phase locking loop for accurately capturing the test signal frequency is introduced into the virtual digital phase locking technique. The validity and feasibility of the virtual digital phase locking frequency parameter measuring method are proved through measuring the practical phase modulation beat signal..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 112001 (2015)
Instrumentation, Measurement and Metrology
Angle Measurement Error Correction of Vehicle-Borne Theodolite Based on the Rotation of Plane Equation
Jiang Bo, Mei Chao, Liang Yuanqing, Jiang Kai, and Zhou Sizhong
The base-platform deformation and uneven of vehicle-borne photoelectric theodolite can lead to the theodolite angle measurement error larger than before. In order to improve the precision, the error should be corrected. With the level measurement meter, the angle of the platform and the horizontal plane can be measuredThe base-platform deformation and uneven of vehicle-borne photoelectric theodolite can lead to the theodolite angle measurement error larger than before. In order to improve the precision, the error should be corrected. With the level measurement meter, the angle of the platform and the horizontal plane can be measured. Based on the measurement results, an analytic geometry method of plane rotation changes is put forward for converting the results to the vertical axis tilt angle and azimuth tilt angle, and then the alignment error is analyzed，which is caused by the calculation method during measurement. At last，the relationships of composition error, alignment error, and the tilt of the platform are analyzed. The simulation and experimental results show that, within the vehicle leveling accuracy of 300″, the vehicle-borne theodolite comprehensive angle error is less than 16″, and the high precision measurement can be realized..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 112002 (2015)
Azimuth Measurement System Based on Triangle Wave Magneto-Optical Modulation
Yang Zhiyong, Cai Wei, and Wu Fancheng
In order to improve the measurement precision of the traditional azimuth measurement system theoretically, as the new modulation signal, triangle wave is introduced into the system, and the method of measuring azimuth based on triangle wave magneto-optical modulation is present. In the new method, the model of modulatiIn order to improve the measurement precision of the traditional azimuth measurement system theoretically, as the new modulation signal, triangle wave is introduced into the system, and the method of measuring azimuth based on triangle wave magneto-optical modulation is present. In the new method, the model of modulation signal is present, and the model of the signal from modulator is present too according to the Faraday effect and Malous law. The signal from modulator is analyzed, its extremums is detected, the relationship between azimuth and extremums is present, and then the model of measuring azimuth is established. The measurement precision and scale of the new method is analyzed, simulation results show that the measurement precision of the new method is higher than the traditional one, and their measurement scale is same, it provides a new scheme to measuring azimuth in higher-precision..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 112003 (2015)
System Gain Calibration of CCD and Evaluation of Uncertainty
Wang Hongchao, Liu Hongyuan, Wang Hengfei, Ying Chengping, and Wu Bin
System gain is one of the important parameters of charge coupled device (CCD), from which many of the other performance parameters such as quantum efficiency, readout noise, full well CCD and so on are determined. With the development of imaging technology, accurate calibration for the system gain of CCD become more anSystem gain is one of the important parameters of charge coupled device (CCD), from which many of the other performance parameters such as quantum efficiency, readout noise, full well CCD and so on are determined. With the development of imaging technology, accurate calibration for the system gain of CCD become more and more important. The theory of measuring system gain based on photon transfer curve technique is introduced. A method to acquire photon transfer curve by changing light intensity is proposed. At the same time, an experimental setup is constructed to calibrate system gain of CCD precisely. It is shown that the result of calibration is 1.6229e-/ADU which has a good consistency with the method to obtain photon transfer curve by changing exposure time. At last, the uncertainty of this calibration is evaluated..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 112004 (2015)
Recent Progress in Optical Remote Sensing Stereo Mapping Techniques
Yu Da, Liu Jinguo, Zhou Huaide, Chen Jiayu, Zhou Lei, Wang Guoliang, and Zhang Boyan
In view of the satellite attitude measurement accuracy is too low to meet the transmission type stereo mapping application requirements of 1∶50000 topographic scale without ground control points, so the line-matrix charge coupled device array mapping system is firstly used in the world.The image motion velocity vector In view of the satellite attitude measurement accuracy is too low to meet the transmission type stereo mapping application requirements of 1∶50000 topographic scale without ground control points, so the line-matrix charge coupled device array mapping system is firstly used in the world.The image motion velocity vector mathematical model is established, and the method of camera parameters calibration. The high strength, high rigidity, high stability optical mapping platform is designed to meet the requirement of the national infrastructure of surveying and mapping, which is a breakthrough for the key technology of positioning without ground control points. For the future demand, the double area array sensors pushbroom imaging system of surveying and mapping is proposed. The relevant application requirements for super complementary metal-oxide-semiconductor sensor and future technology development is also discussed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 112005 (2015)
Research and Experiment of Satellite Laser Ranging with 1064 nm Wavelength
Meng Wendong, Tang Kai, Deng Huarong, Li Pu, Zhang Haifeng, Wu Zhibo, and Zhang Zhongping
Satellite laser ranging (SLR) is the most common satellite observation technology with the highest single shot measuring precision which usually uses 532 nm wavelength derived from 1064 nm laser. 1064 nm wavelength has many better properties than 532 nm in atmospheric attenuation, photon number, laser power, developmenSatellite laser ranging (SLR) is the most common satellite observation technology with the highest single shot measuring precision which usually uses 532 nm wavelength derived from 1064 nm laser. 1064 nm wavelength has many better properties than 532 nm in atmospheric attenuation, photon number, laser power, development and price, and so on, which is benefit to enhance the system detection ability, and carry out the goal of weak signal detection. The key technology and difficulties are presented in building up a SLR system with the wavelength of 1064 nm, and the corresponding solutions are put forward. With these technologies, the satellite laser ranging based on 1064 nm wavelength in China is successfully carried out for the first time and the experimental foundations have been laid for the further development and application in field of space targets observation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 112006 (2015)
Integrated Optics
Study on Splitting Management Characteristics of Ring Resonance Cavity Based on Photonic Crystal Waveguide
Liu Yunfeng, Liu Bin, He Xingdao, Li Xiang, Qian Jiachen, and Gong Qiang
A kind of waveguide ring resonator structures based on two-dimensional square lattice photonic crystal is reported. The transmission characteristics are researched by finite element methodnumerical simulation. The results show that by changing the structural parameters of adjustable rods in ring cavity, the resonance fA kind of waveguide ring resonator structures based on two-dimensional square lattice photonic crystal is reported. The transmission characteristics are researched by finite element methodnumerical simulation. The results show that by changing the structural parameters of adjustable rods in ring cavity, the resonance frequency of resonance cavity can be effectively adjusted, and according to the diffident resonance modes of the resonance cavity, a good band-pass filter and beam splitting characteristics are achieved. As an example with a 1×2 beaming splitter, by changing the structure parameters of adjustable rods in ring cavity regularly, the intensity modulation to each port output light can be realized. This feature has certain potential application value in the all-optical network..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 113001 (2015)
Lasers and Laser Optics
25Gb/s Electroabsorption Modulator Monolithically Integrated with Distributed Feedback Laser
Zhou Daibing, Bian Jing, An Xin, Wang Baojun, Zhang Ruikang, Zhao Lingjuan, Ji Chen, and Wang Wei
A 25 Gb/s InGaAsP/InGaAsP multi-quantum wells electro-absorption modulator monolithically integrated with distributed feedback laser is fabricated by selective area growth. The photoluminescence wavelength variation is 38 nm between the laser area wavelength λPL of 1535 nm and modulator area wavelength λPL of 1497 nm. A 25 Gb/s InGaAsP/InGaAsP multi-quantum wells electro-absorption modulator monolithically integrated with distributed feedback laser is fabricated by selective area growth. The photoluminescence wavelength variation is 38 nm between the laser area wavelength λPL of 1535 nm and modulator area wavelength λPL of 1497 nm. The grating is fabricated at the laser region by holographic lithograph technology. The threshold current of thip lasers is 18 mA and the power is over 10 mW at 100 mA with wavelength of 1549 nm. The side-mode suppression ratio is over 40 dB. Extinction ratio is 23 dB by coupling light into the single mode fiber. The 3 dB-bandwidth of 16 GHz has been measured. A 25 Gb/s eye diagram is measured with a 3.5 V non-return to zero (NRZ) pseudorandom modulation signal at -1.9 V bias. A clearly opening eye-diagram with a dynamic extinction ratio of 5.7 dB has been obtained. This laser is appropriate for next generation of optical fiber transmission systems for its high bandwidth and low cost..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 114001 (2015)
Generation of Laser Pulse with Steep Leading Edge by Laser Interacting with a Thin Plasma Foil
Xia Changquan
The shaping effects for the intense laser pulse of a low-density plasma foil is investigated by numerical simulation employing a one dimensional particle-in-cell (PIC) code. Laser pulses with steep leading edge of different pulse durations are obtained by changing the thickness of the plasma foil.The results show that The shaping effects for the intense laser pulse of a low-density plasma foil is investigated by numerical simulation employing a one dimensional particle-in-cell (PIC) code. Laser pulses with steep leading edge of different pulse durations are obtained by changing the thickness of the plasma foil.The results show that a moving-electron-layer (MEL) is generated and driven forward by the radiation pressure, the leading edge is reflected by the MEL and the main part of the pulse is transmitted when the MEL reaches the rear surface of the foil. The single MEL vanishes quickly without double-layer structure, so the peak power of the pulse has no obvious attenuation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 114002 (2015)
Q-Switched and Q-Switched Mode-Locking Operation from Nd∶YVO4 Laser using Reflective MoS2 Saturable Absorber
Li Pingxue, Zhang Guangju, Zhang Han, Zhao Chujun, Chi Junjie, Hu Haowei, Yao Yifei, and Su Ning
The generation of both Q-switched and Q-switched mode-locking pulses from Nd∶YVO4 laser using reflective MoS2 saturable absorber is reported. The Nd∶YVO4 laser system is designed as a folded cavity. At the absorbed pump power of 4.47 W, Q-switched pulses with average output power of 87.2 mW are obtained. The Q-switchedThe generation of both Q-switched and Q-switched mode-locking pulses from Nd∶YVO4 laser using reflective MoS2 saturable absorber is reported. The Nd∶YVO4 laser system is designed as a folded cavity. At the absorbed pump power of 4.47 W, Q-switched pulses with average output power of 87.2 mW are obtained. The Q-switched mode-locking operation with average output power of 95.3 mW is achieved at the absorbed pump power of 4.75 W. The wavelength of the ultrashort pulses is centered at 1064.39 nm. The experimental results are analyzed, and a good preparation is made for the next-step work..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 114003 (2015)
A Circuit Design Method for Alternating Current Light-Emitting Diode
Li Hao, Zhang Huanyue, Zhang Jinghui, Cao Fan, Zou Nianyu, and Gao Yingming
Alternating current passing through alternating current light-emitting diode (AC LED) makes it not reasonable to decide luminous flux of AC LED by simply multiplying electric power and luminous efficiency. Based on alternating current effective current and light-emitting diode photoelectric characteristics, concept of Alternating current passing through alternating current light-emitting diode (AC LED) makes it not reasonable to decide luminous flux of AC LED by simply multiplying electric power and luminous efficiency. Based on alternating current effective current and light-emitting diode photoelectric characteristics, concept of AC LED equivalent luminous efficiency is introduced, and equations concerning luminous flux and luminous efficiency on equivalent luminous efficiency and the number LEDs-connected in series are established separately, then character of actual luminous flux and luminous efficiency curve are discussed. A method used to design AC LED is proposed, according to given luminous flux. Through the method theoretical AC LED luminous flux, proved less than actual value by experiment, the biggest difference is calculated..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 114004 (2015)
High Homogenization Diode Laser Stack Beam Shaping System
Lei Chengqiang, Wang Yuefeng, Yin Zhiyong, Yin Shaoyun, Sun Xiuhui, and Zhou Quan
Intensity distribution of diode laser is not uniform due to the broad-area and ridge-waveguide designs, poor beam quality is the limiting factor of industrial applications. In order to achieve homogenized spot by beam shaping of high-power diode laser stack, a homogenization system for diode laser stack based on microlIntensity distribution of diode laser is not uniform due to the broad-area and ridge-waveguide designs, poor beam quality is the limiting factor of industrial applications. In order to achieve homogenized spot by beam shaping of high-power diode laser stack, a homogenization system for diode laser stack based on microlens array is designed. The diode laser beam shaping theory of microlens array is analyzed. The lower limit of clear aperture of microlens is confirmed by analysis of the impact of the diffraction of microlens edge on the spot homogeneity. The simulation and experimental test are carried out for the microlens array beam shaping system by a diode laser stack with 6 bars, realizing the spot with the homogeneity of 92.59% and energy utilization of 91.19%. The beam shaping system can be well used in diode laser welding, cladding, surface hardening and other industrial fields..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 114005 (2015)
High Power High Beam Quality 1060-nm Large Optical Cavity Asymmetric Waveguide Semiconductor Laser Diode
Tan Shaoyang, Wang Hao, Zhang Ruikang, Lu Dan, Wang Wei, and Ji Chen
High power high beam quality 1060-nm InGaAs/GaAs quantum well (QW) semiconductor laser diode with an asymmetric large optical cavity (LOC) is designed and fabricated. The laser diode consists of compressively strained double InGaAs/GaAs quantum wells and a GaAs/AlGaAs separate confinement structure. To improve the highHigh power high beam quality 1060-nm InGaAs/GaAs quantum well (QW) semiconductor laser diode with an asymmetric large optical cavity (LOC) is designed and fabricated. The laser diode consists of compressively strained double InGaAs/GaAs quantum wells and a GaAs/AlGaAs separate confinement structure. To improve the high power performance, the transversal optical cavity is optimized to have low fast axis far-field divergence angle, large optical spot size and low facet optical density, low internal optical absorption loss and high internal quantum efficiency. By employing a weak optical confinement Al0.1Ga0.9As waveguide with thickness of 4 μm, a low transversal far-field divergence angle of 20° and large optical spot size near 1 μm are obtained. By detuning the QW position, the asymmetric waveguide with thinner p-side waveguide enables the laser diode high internal quantum efficiency even in high current injection level. Based on the optimization, 1.3 W continue wave optical power is achieved for broad area lasers with cavity length and strip width of 2 mm and 50 μm, respectively. For single spatial mode ridge waveguide laser diodes with same cavity length, 600 mW continue wave optical power is obtained at 10 ℃..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 114006 (2015)
Investigation on Depolarization of Slab Amplifiers on Integration-Test-Bed
Chen Lin, Xie Xudong, Chen Yuanbin, Liu Jianguo, Wang Zhenghui, Hao Xin, Liu Yong, and Zheng Kuixing
Xenon lamp-pumped Ndglass will result in uneven temperature rise, which will produce thermal stress birefringence and induce depolarization. Depolarization will directly reduce the system efficiency, beam quality. So, it is important to confirm the temperature distribution and stress distribution, to accurately predictXenon lamp-pumped Ndglass will result in uneven temperature rise, which will produce thermal stress birefringence and induce depolarization. Depolarization will directly reduce the system efficiency, beam quality. So, it is important to confirm the temperature distribution and stress distribution, to accurately predict the resulting depolarization of the beam, and to design rational beam filling factor. Based on the electro-optical conversion model, we used three-dimensional ray tracing to obtain the distribution of thermal power source. with heat conduction theory, we calculated the three-dimensional temperature distribution of the laser glass and the stress distribution and the resulting depolarization distribution. The results show that the stress birefringence within the beam diameter is small, but the four corners of square beam department of the stress birefringence are more serious, with the largest depolarization about 0.13%. The results are consistent with the experimental results of Lawrence Livermore national laboratory. The near field results of outputted laser show that the thermal induced depolarization of the slab amplifiers satisfies the output design demand of high energy equipment..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 114007 (2015)
Experimental Study on Laser Thermal Stress Forming of High Strength Steel
Wu Qiang, Xu Lanying, Yang Yongqiang, and Kong Chunyu
Many laser thermal stress forming experiments of high strength steel plate used automobile are done by CO2 laser and the material relevant microstructures are analyzed. Based on the deep study of the changing law on the specimen bending angle, the process parameters are reasonably optimized about laser thermal stress fMany laser thermal stress forming experiments of high strength steel plate used automobile are done by CO2 laser and the material relevant microstructures are analyzed. Based on the deep study of the changing law on the specimen bending angle, the process parameters are reasonably optimized about laser thermal stress forming. Namely the effect of thermal stress forming is the best when the laser power is 1.5 kW, scanning times are 6, the scanning speed is 1.5m/min and the diameter of laser spot is 3.5 mm and the surface energy changes between 20~45 J/mm2. The conditions are proposed to avoid the ablation phenomenon on the work piece surface. The test results show that the bending angle tends to the direct proportion relationship with laser scanning times, scanning velocity and material width in the effective range of the test parameters. That is a linear relationship when the spot diameter is the less or the more. The effect of the laser power is nonlinear obviously, but the bending angle tends to the direct proportion relationship with the laser power when the laser power is less. The microcosmic grain is smaller near the material surface and the carbide precipitation is less farther the surface..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 114008 (2015)
Generation and Application Technology of Modulated Light Based on Ultraviolet LED Array
Wang Shaoshui, Sun Quanshe, Zhao Facai, and Han Zhong
Working principle, advantages and disadvantages of ultraviolet (UV) discharge lamp, UV LED and UV laser are introduced. UV modulated light is developed using UV LED as the original light, can produce standard UV modulation signal with different modulation rates and different duty ratios. In order to solve traceability Working principle, advantages and disadvantages of ultraviolet (UV) discharge lamp, UV LED and UV laser are introduced. UV modulated light is developed using UV LED as the original light, can produce standard UV modulation signal with different modulation rates and different duty ratios. In order to solve traceability of optical power, the modulated light is outputted by optical fiber. The experimental results show that the modulated light meets the requirements of UV communication receiver sensitivity test, whose optical fiber output coupling efficiency of UV source modulation is about 8%, and the maximum modulation rate is higher than 2 MHz..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 114009 (2015)
Materials
Study on Enhancement Effects of a Grating Electrode in Organic Solar Cells
Xiao Xiao, Xu Defu, Xiao Zhigang, Deng Chi, Li Xian, Zhang Zhiyou, and Du Jinglei
There is a significant mismatch between the optical absorption properties and electrical transmission properties in organic active layer, this contradiction is regarded as a main reason for limiting the conversion efficiency of organic solar cells (OSC). Fortunately, plasmonic light trapping has emerged as an effectiveThere is a significant mismatch between the optical absorption properties and electrical transmission properties in organic active layer, this contradiction is regarded as a main reason for limiting the conversion efficiency of organic solar cells (OSC). Fortunately, plasmonic light trapping has emerged as an effective technology to overcome this mismatch. Metal gratings are embedded in OSCs as bottom electrodes, and an OSC structure based on plasmonic grating electrode is proposed. Furthermore, optical field distributions in OSCs are numerically investigated by finite difference in time domain, and the plasmonic enhancement effects of metal gratings are analyzed. The results show plasmonic gratings have excellent light trapping ability and response to incident angle, so there is obvious light absorption enhancement in active layer..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 116001 (2015)
Effect of TiO6 Octahedron Structure Defects on the Electronic Structure and Optical Properties of CaCu3Ti4O12 by First-Principles
Yang Wenlong, Xiu Hanjiang, Xiong Yanling, Wang Li, and Sun Hongguo
TiO6 octahedron structure is the basic framework of CaCu3Ti4O12 (CCTO), which associates with performance of optical and electronic properties, the investigation of dielectric and optical properties under various frequency region contribute to reveal origin of high dielectric constant. In order to explore the contributTiO6 octahedron structure is the basic framework of CaCu3Ti4O12 (CCTO), which associates with performance of optical and electronic properties, the investigation of dielectric and optical properties under various frequency region contribute to reveal origin of high dielectric constant. In order to explore the contributions of TiO6 octahedron to optical and electronic properties under various frequency region and the impacts of titanium and oxygen element, the model of ideal CCTO bulk, CCTO with oxygen vacancy and titanium vacancy are established, the structure, electronic density distribution and optical properties of three models are calculated and analyzed by plane-wave pseudo-potential method of first-principle calculation based on density functional theory. The calculated results show that oxygen vacancy and titanium vacancy have significant influences on structure and electronic density distribution, moreover, the optical properties such as refractive index, reflectivity, absorbance, and optical conductivity are deduced from the calculated dielectric function of three models above, and oxygen vacancy affect anisotropic of CCTO optical properties crucially..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 116002 (2015)
Great Impacts of the Dielectriclayer in a Four-Fan-Rings-Shaped Metamaterial on the Absorption of Electromagnetic Waves
Xu Wan, Yan Changchun, Shi Junxian, Jiang Xia, Zhu Qing, Zhang Wenchao, and Li Dongdong
A metamaterial that acts as a strongly resonant absorber with a periodic structure in which each unit cell consists of a metal-insulator-metal structure is presnted. The top metal layer consists of four-fan-rings-shaped gold blocks. Simulating electromagnetic responses of the structure, the structure achieves a good abA metamaterial that acts as a strongly resonant absorber with a periodic structure in which each unit cell consists of a metal-insulator-metal structure is presnted. The top metal layer consists of four-fan-rings-shaped gold blocks. Simulating electromagnetic responses of the structure, the structure achieves a good absorption at visible and ultraviolet frequencies is demonstrated. Furthermore, when change the shape, size and permittivity of the dielectriclayer under the four-fan-rings-shaped gold layer, the dielectriclayer has a great influence on the absorption of the metamaterial. Simulations show that the resonant frequency of the resonator ranges from visible region to ultraviolet region when the dielectriclayer set to Al2O3, four-fan-rings-shaped, and appropriate size. The great absorption of the structure over 90% has the relative absorption line width of 0.76. The proposed structure provides theoretical basis for the design and fabracation of the electromagnetic absorbers..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 116003 (2015)
The Transmission Characteristics of Corrugated Metal Parallel-Plate Waveguide
Yang Jianfeng, Yang Jingjing, Yan Su, Deng Wei, and Huang Ming
The corrugated metal parallel plate waveguide composed by two parallel plates with subwavelength corrugations on both surfaces shows some similarities and differences with plasmon-assisted parallel plate waveguide are confirmed. A symmetrical corrugated metal parallel plate waveguide with gradually changed depth of corThe corrugated metal parallel plate waveguide composed by two parallel plates with subwavelength corrugations on both surfaces shows some similarities and differences with plasmon-assisted parallel plate waveguide are confirmed. A symmetrical corrugated metal parallel plate waveguide with gradually changed depth of corrugations is designed to convert electromagnetic wave between transmission mode and surface mode. Due to the field distribution and the power flow are concentrated on the corrugated surface at the intermediate region of the waveguide, a cylindrical perfect electric conductor put into the center of the waveguide does not affect its field distribution and transmission characteristics, namely the waveguide has stealth effect. The cutoff frequency of the upper sideband of corrugated metal parallel plate waveguide’s band gap changes linearly with the permittivity of sample substance which is filled in the corrugations, and therefore it can be used in dielectric sensing. The terahertz sensing characteristics are confirmed by the detection of samples such as diesel, liquid paraffin and olive oil. This work is helpful for exploring the application of the corrugated metal parallel plate waveguide in terahertz wave transmission, manipulation and terahertz device design..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 116004 (2015)
Properties of Graphene and Antenna Applications in Microwave to THz
Xie Yanan, Liu Zhikun, Geng Li, Pan Dengke, and Song Pan
Graphene’s conductivity is governed by intraband contributions in microwave to terahertz band. The dependence of the surface conductivity, the equivalent surface impedance and permittivity on the chemical potential and temperature using the intraband conductivity model are studied. The surface conductivity and equivaleGraphene’s conductivity is governed by intraband contributions in microwave to terahertz band. The dependence of the surface conductivity, the equivalent surface impedance and permittivity on the chemical potential and temperature using the intraband conductivity model are studied. The surface conductivity and equivalent surface impedance largely depend on the chemical potential, and hardly depend on the temperature. So the graphene has tunable surface conductivity and impedance. The effective surface plasmon polaritons mode index of the infinite planar graphene based on the intraband conductivity model and the dispersion relation of TM (transverse magnetic) modes of graphene’s SPP (surface plasmon polaritons) are researched. The result proves that graphene-based plasmonic resonant antennas are expected to be smaller than traditional material antennas. So the graphene antennas are tunable, stable and miniature. The dependence of transmission coefficient on chemical potential based on the property of electromagnetic waves is studied. The transmission coefficient largely depends on the chemical potential so as to make the material possible for tunable THz filter. Flexible graphene antenna is designed. The good gain is observed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 116005 (2015)
Medical Optics and Biotechnology
Research of Heat Accumulation of Laser Irradiated Biological Cells
Wang Xiaona, Xu Xi, Cao Chaojie, Guo Weinan, and Song Shide
Photo-thermal effect is one of the most important effects in the interactions between laser and biological tissue cells, however, its generation, transmission and action mechanisms are not yet clear. When laser irradiates biological cells, temperature is the decisive parameter in that temperature change in biological cPhoto-thermal effect is one of the most important effects in the interactions between laser and biological tissue cells, however, its generation, transmission and action mechanisms are not yet clear. When laser irradiates biological cells, temperature is the decisive parameter in that temperature change in biological cells reflects a variety of physical properties of cells, which plays an important role in clinical applications. A numerical simulation model is built, and the heat accumulation process is simulated and analyzed using finite element software according to the heat transfer equations when laser irradiates biological cells. The temperature variation process of biological cells under different chopping cycles is analyzed, and equations of two temperature rise processes and two temperature drop processes are fitted when the chopper period is 0.1 s and the irradiation time is 0.2 s. It is concluded that the phenomenon of heat accumulation will appear only when the chopping frequency reaches a certain value; the highest temperature of thermal model which is irradiated by laser is related to the chopping frequency, and the higher the chopping frequency is, the lower the biological cell′s thermal effect is..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 117001 (2015)
Nonlinear Optics
Study of Conserved Quantities and Characteristics of Nonlinear Helmholtz Solitons
Zhang Bingzhi, Chen Zhifeng, Deng Rongbiao, Huang Feng, and Zheng Yanhua
Three conserved quantities of non-paraxial nonlinear Helmholtz equation are driven in theory, which are corresponding to the conserved quantities of nonlinear Schdinger equation (power, Hamiltonian, momentum). Formally, these conserved quantities can be simplified as that of the paraxial model when the non-paraxial teThree conserved quantities of non-paraxial nonlinear Helmholtz equation are driven in theory, which are corresponding to the conserved quantities of nonlinear Schdinger equation (power, Hamiltonian, momentum). Formally, these conserved quantities can be simplified as that of the paraxial model when the non-paraxial term is ignored. In addition, the difference between the non-paraxial nonlinear Helmholtz model and the paraxial nonlinear Helmholtz model by analyzing the variation characteristics of the conserved quantities with the change of parameters of optical spatial solitons is studied. Especially, it is found that the divergence results of the Hamiltonian and momentum of optical spatial solitons can be suppressed in the non-paraxial model when transverse speed increases in paraxial model..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 119001 (2015)
Plasmonic Slot Waveguides for Third Harmonic Generation and Third-Order Parametric Down-Conversion
Sun Yunxu, and Zhang Jianyu
The researches of third harmonic generation (THG) and third-order parametric down-conversion (TPDC) always encounter the problem of phase mismatching with such a large frequency span. Waveguides modal dispersion is an effective tool to compensate the material dispersion. However, the nonlinear polarization form of THG The researches of third harmonic generation (THG) and third-order parametric down-conversion (TPDC) always encounter the problem of phase mismatching with such a large frequency span. Waveguides modal dispersion is an effective tool to compensate the material dispersion. However, the nonlinear polarization form of THG or TPDC is an odd function that will be almost zero if the mode field distribution contains opposite sign components. Several asymmetric plasmonic slot waveguides infiltrated in nonlinear organic material (2-\[4(dimethylamino)phenyl\]-3-f\[4-(dimethylamino)phenyl\]ethynylgbuta-1,3-diene-1,1,4-tetracarbonitrile) (DDMEBT) with high third-order susceptibility are proposed. Silicon (Si) is used to fill the bottom metallic slot region to break the symmetry of the waveguide. Silver (Ag) is considered to be the metal medium due to its low loss. The needed phase-matching condition (PMC) is satisfied between the zeroth mode at fundamental frequency (FF) and the first mode at third harmonic (TH) by appropriate designing the waveguide geometrical parameters. The corresponding overlap factor for THG or TPDC is much larger than the symmetric distribution..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 119002 (2015)
Optical Design and Fabrication
Method to Fabricate Spiral Phase Plate with Continous Surface by One Exposure Processing
Shi Lifang, Cao Axiu, Guo Shuji, Luo Xue, Qin Yanyun, and Deng Qiling
A method for fabricating spiral phase plate (SPP) with continuous surface is proposed. An interval is used to quantize the three dimension surface of SPP into two dimension bars to form a binary mask. The exposure dose can be precisely modulated through this mask in the exposure process. The select criterion of the quaA method for fabricating spiral phase plate (SPP) with continuous surface is proposed. An interval is used to quantize the three dimension surface of SPP into two dimension bars to form a binary mask. The exposure dose can be precisely modulated through this mask in the exposure process. The select criterion of the quantization interval is discussed in detail. As the results, four kinds of high-quality SPPs with topological charges 1,3,10 and 20 are fabricated which can be used under the wavelength of 532 nm. The corresponding optical effects are also measured..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 122001 (2015)
Optimization Design of Long Wave Infrared Rays and Laser Optical System with Conformance Structure
Mei Chao, Cao Jianzhong, Yang Hongtao, Guo Zheyuan, and Liang Yuanqing
In order to improve the precision of small measure equipment, the manuscript presents a structure of common aperture, long wave infrared rays/laser dual-mode measure equipment. Then an optical system is designed to match the system’s needs. The long wavelength infrared imaging system and the laser receiver, laser emissIn order to improve the precision of small measure equipment, the manuscript presents a structure of common aperture, long wave infrared rays/laser dual-mode measure equipment. Then an optical system is designed to match the system’s needs. The long wavelength infrared imaging system and the laser receiver, laser emission system use the same protect window, the far infrared imaging system and the laser receiver use the same aperture and reflector, in this way the size of optical system is reduced. The volume of the whole optical system is 450 mm×164 mm×164 mm, coincident with the requirement of small and light. At last, analysis the performances of each optical systems by the software, the modulation transfer function of the far infrared imaging system is above 0.23 at 30 lp/mm, the optical path difference of the laser receiver is smaller than 1/4 wavelength, the spot diagram of laser emission system is smaller than 10 μm, all of them can match the project requirement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 122002 (2015)
Numerical Simulation Analysis of Oblique Impinging Jet Flow Field of Different Nozzle Structure
Luo Yinchuan, Mi Shaogui, and Zhang Rongzhu
Fluid jet polishing is a new precision optical machining method. The application of multiple nozzle structure and rectangular nozzle structure can effectively improve the polishing efficiency. Impact angle affects the hydrodynamic characteristics of impingement, which has an important influence on material removal and Fluid jet polishing is a new precision optical machining method. The application of multiple nozzle structure and rectangular nozzle structure can effectively improve the polishing efficiency. Impact angle affects the hydrodynamic characteristics of impingement, which has an important influence on material removal and polishing effect. Therefore it is necessary to further analyze the flow field distribution characteristics of different nozzle structures with different impact angles. The circular single nozzle jet model, multi-nozzle and rectangular nozzle jet model with different impact angles are built. Based on the fluid mechanics theory, the oblique impingement process of different nozzle structure jets is numerical simulated by FLUENT, and the fluid jet velocity and pressure distribution curves on the workpiece wall have been obtained..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 122003 (2015)
New Method for All Movable Zoom Lens First Order Design
Huang Hao, Li Xiangning, and Song Qiang
In order to get the simple computational formula for all movable zoom lens and reduce excessive dependence on designing experience of zoom lens, a new way to calculate optical-power distribution of zoom system is proposed.Taking the medium zoom position as initial parameter and the distances of groups as independent vaIn order to get the simple computational formula for all movable zoom lens and reduce excessive dependence on designing experience of zoom lens, a new way to calculate optical-power distribution of zoom system is proposed.Taking the medium zoom position as initial parameter and the distances of groups as independent variables, the motion differential equations of all zoom positions is generated. With algorithm of partical swarm optimization under certain constraints, the best solutions are gotten, which are the positions of all groups in all zoom positions. This method reduces the difficulty of optical-power distribution in zoom lens system. What’s more, it provides a new way to get initial Gauss parameters of zoom system. A 100× Gauss structure with six components zoom system is designed, and the feasibility of this method is proved with it. The method can provide a practical and technical reference for all movable zoom lens system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 122004 (2015)
Grinding 2 m Diameters Aspheric SiC Mirror with Multi-Mode Optimization Technique
Liu Zhenyu
Use multi-mode optimization technique to improve material remove efficiency and precision. Introduced principal theory and mathematical model of multi-mode optimization technique. Compared with traditional computer controlled optical surfacing (CCOS) technique, we introduce the advantage of multi-mode technique. In theUse multi-mode optimization technique to improve material remove efficiency and precision. Introduced principal theory and mathematical model of multi-mode optimization technique. Compared with traditional computer controlled optical surfacing (CCOS) technique, we introduce the advantage of multi-mode technique. In the last, we grind a SiC mirror using multi-mode technique. Take SiC mirror with caliber of 2040 mm as an example to introduce how the multi-mode technique applied in grind large aspheric SiC mirror. After a complete multi-mode process, peak valley (PV) of the surface converges from 8.72 μm to 4.91 μm and root mean square (RMS) of the surface converges from 0.91 μm to 0.52 μm， which demonstrates the validity of the multi-mode technique..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 122005 (2015)
Wave-Front Fitting Capability Analysis of 61-Element Voice Coil Deformable Mirrors
Sun Xiaolin, Guan Chunlin, and Zhou Hong
Deformable mirrors is the key element for adaptive optics system, and wave-front fitting capability is the main parameter. The Ansys software is used to calculate the actuator′s influence function. Fitting capability is compared, which is based on the three arrangement schemes (diamond arrangement, square arrangement, Deformable mirrors is the key element for adaptive optics system, and wave-front fitting capability is the main parameter. The Ansys software is used to calculate the actuator′s influence function. Fitting capability is compared, which is based on the three arrangement schemes (diamond arrangement, square arrangement, annular arrangement) fitting low order primitive aberrations and 1000 frames combination of Zernike aberration. Simulation results show that annular arrangement is the best actuator arrangement schemes of contactless force actuator deformable mirror, and the average root-mean-square value of fitting combination aberration is 0.016 μm； annular arrangement deformable mirror also has a good fitting capability to the defocus and astigmatism when its peak valley value is larger than 30 μm and 15 μm. The influence of a broken actuator on the deformable mirror fitting capability is analyzed. Results show that it has little influence on the deformable mirror fitting capability, its root-mean-square value increment is below 0.01 μm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 122006 (2015)
Optical Devices
Theoretical Calculations of Cube Corner Retro-Reflector
Jiao Zhongke, Yue Yongjian, and Liu Bo
Maximum incident angles of triangular circular and hexagonal retro-reflector in different incident parameters and the calculations of the effective reflection area of different reflectors in different incident parameters are derived. Comparisons are made between different reflectors. The calculations of maximum incidenMaximum incident angles of triangular circular and hexagonal retro-reflector in different incident parameters and the calculations of the effective reflection area of different reflectors in different incident parameters are derived. Comparisons are made between different reflectors. The calculations of maximum incident angle and effective reflection area provid theoretical foundation for the design of corner retro-reflector array, the calculation of echo energy and the study of far-field diffraction spot..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 123001 (2015)
Scattering
Evaluation Criteria of Inversion Algorithm for Dynamic Light Scattering
Liu Wei, Wang Yajing, Chen Wengang, and Shen Jin
Small changes of parameters of inversion algorithm for dynamic light scattering will result in large deviation of its solution. In order to improve the measurement accuracy, it is need to establish a set of criteria to evaluate the solution of inversion algorithm. The paper analyses the inversion algorithms in three asSmall changes of parameters of inversion algorithm for dynamic light scattering will result in large deviation of its solution. In order to improve the measurement accuracy, it is need to establish a set of criteria to evaluate the solution of inversion algorithm. The paper analyses the inversion algorithms in three aspects: fitting precision of correlation function, stability of particle size distribution, and repeatability of solution, then proposes three evaluation criteria. Criteria I: root mean square (RMS) error of fitting correlation function should be smaller than 0.001, quality factor(Q) of error should be Q>0.7; criteria II: sample standard deviation (RN) of the norm of particle size distribution should be RN<5%; criteria III: relative standard deviation (RSD) of the solution should be smaller than 2%. Experimental data show that in case of the inversion algorithm meets all three evaluation criteria, it can be obtained the most close to the actual measurement results with good stability and high repeat precision..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 129001 (2015)
Analysis of Scattering of Laguerre-Gaussian Vortex Beam by Biological Cells
Qu Tan, Wu Zhensen, Wei Yinyu, Li Zhengjun, and Bai Lu
The beam width of Laguerre-Gaussian vortex beam is derived by using intensity momentum method. Using the expression of Hermite-Gaussian beam in terms of spherical vector wave functions by complex source point method, and combining with the transformation between Laguerre polynomial and Hermite polynomial, Laguerre-GausThe beam width of Laguerre-Gaussian vortex beam is derived by using intensity momentum method. Using the expression of Hermite-Gaussian beam in terms of spherical vector wave functions by complex source point method, and combining with the transformation between Laguerre polynomial and Hermite polynomial, Laguerre-Gaussian vortex beam is expanded in terms of spherical vector wave functions. Utilizing the generalized Lorenz Mie theory, the scattering of Laguerre-Gaussian vortex beam by cancer cells is investigated. The intensity and phase distribution at cross section perpendicular to the propagation axis with different beam modes and different propagation distances is analyzed numerically. The results show that with the increase of the radial and azimuthal mode index and the propagation distance, the size of the beam increases. The phase distribution of Laguerre-Gaussian vortex presents different characteristics from source plane with the increase of propagation. Stemming from the intensity distribution of Laguerre-Gaussian vortex beam, the scattering properties are interpreted..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 129002 (2015)
Nonnegative Iterative TSVD Inversion Algorithm for Nanoscale Particle Sizing
Tan Chengxun, Liu Wei, Chen Chen, Wang Yajing, Chen Wengang, and Shen Jin
Nanoscale particle size distribution can be inverted by truncated singular value decomposition (TSVD) method. However, it is difficult to select the optimal truncated parameter. Based on the analyzation of TSVD method, we present a nonnegative iterative truncated singular value decomposition (NNI-TSVD) method for obtaiNanoscale particle size distribution can be inverted by truncated singular value decomposition (TSVD) method. However, it is difficult to select the optimal truncated parameter. Based on the analyzation of TSVD method, we present a nonnegative iterative truncated singular value decomposition (NNI-TSVD) method for obtaining the particle size distribution of nanoscale particle suspensions from dynamic light scattering data. Furthermore, we modify the L-curve criterion for choosing the optimal truncated parameter.Experimental data show that with the NNI-TSVD method, its optimal truncated parameter selected by the second truncated L-curve criterion, can be employed to accurately get the average size and size distribution of unimodal suspensions. The relative error of the inverted average diameter is less than 3%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 129003 (2015)
Spectroscopy
Determination of Dibutyl Phthalate with THz Time-Domain Spectroscopy
Zhao Lijun, Gao Lei, Jiang Chen, Yi Lingxue, Yu Xianshu, and Zhao Kun
This paper adopts terahertz time-domain spectroscopy to identify dibutyl phthalate(DBP), one kind of industrial plasticizer. Terahertz time-domain spectroscopy techniques are used to obtain time-domain spectroscopy(0.2～1.5 THz) of different DBP concentrations in ethyl alcohol and n-hexane at room temperature in nitrogeThis paper adopts terahertz time-domain spectroscopy to identify dibutyl phthalate(DBP), one kind of industrial plasticizer. Terahertz time-domain spectroscopy techniques are used to obtain time-domain spectroscopy(0.2～1.5 THz) of different DBP concentrations in ethyl alcohol and n-hexane at room temperature in nitrogen atmosphere. Optical parameters calculation results show that refractive index, absorption coefficient and other optical parameters in 0.2～1.5 THz band of DBP/n-hexane and DBP/Ethyl alcohol solutions correspond with concentrations. According to the absorption coefficient, refractive index and correlations between frequency-domain spectroscopy of area and concentration, it can be obtained content of DBP in any unknown solutions. The results could help to provide a new way and new method to identify phthalate acid esters (PAEs) in white spirit or other soft drinks..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 130001 (2015)
Mental Workload Classification and Measurement Using Functional Near-Infrared Spectroscopy (fNIRS)
Pan Jinjin, Jiao Xuejun, Wang Chunhui, Chen Shanguang, Jiao Dian, Jiang Jin, and Zhang Zhen
The objective is to use functional near-infrared spectroscopy (fNIRS) to classify and measure mental workload in n-back tasks. Prefrontal cortex (PFC) responses were monitored with fNIRS while 18 subjects completed n-back tasks, performance and NASA-TLX scales were also recorded. It was found that there was significantThe objective is to use functional near-infrared spectroscopy (fNIRS) to classify and measure mental workload in n-back tasks. Prefrontal cortex (PFC) responses were monitored with fNIRS while 18 subjects completed n-back tasks, performance and NASA-TLX scales were also recorded. It was found that there was significant difference in performance, subjective scores, and fNIRS data under different difficulty tasks; dorsolateral prefrontal cortex (DLPFC) is more sensitive to fNIRS in PFC; using support vector machine (SVM) could realize accurate classification of 4 mental workload levels; SVM decision values could assess and predict mental workload effectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 130002 (2015)
Resonance-Enhanced Multiphoton Ionization Spectrum of np Rydberg State of SO2
Zhang Lianshui, Zhao Zhanlong, He Wanlin, Zhang Miao, and Zhang Guiyin
The Rydberg state of SO2 has been studied experimentally using the technology of resonance-enhanced multiphoton ionization (REMPI) spectra, where a wavelength tunable high-power pulse laser is used as the excitation source. The REMPI spectra similar to atomic absorption spectra of alkali metal have been obtained in theThe Rydberg state of SO2 has been studied experimentally using the technology of resonance-enhanced multiphoton ionization (REMPI) spectra, where a wavelength tunable high-power pulse laser is used as the excitation source. The REMPI spectra similar to atomic absorption spectra of alkali metal have been obtained in the range of 420~540 nm. The ionization peaks appearing at 429.3 nm and 452.3 nm correspond to the (4+1) REMPI, and the ionization peak at 529.4 nm corresponds to the (4+2) REMPI. The higher electronically excited state appearing in the spectra should be assigned to the Rydberg state series converging to F1A2 with an np orbital (n=4, 5, 6). The scanning of the ionization peak with high precision at 529.4 nm shows that the spectral structure with nearly equal interval corresponds to the REMPI series of 4p（0, v2, 0） Rydberg state of SO2. The harmonic frequency of bending vibration levels of 4p Rydberg state Δν2 is calculated to be (387.3±12.4) cm-1..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 130003 (2015)
X-Ray Spectral Diagnosis for Z-Pinch Plasma
Liu Lifeng, Xiao Shali, Qian Jiayu, Wei Minxi, and Chen Bolun
In order to study and diagnose the distribution, movement process and shape of the high-temperature plasma of pellet implosion in the Z-pinch implosion, a novel spherically bent crystal imaging system has been developed based on the Bragg diffraction theory. The key component of the imaging system is the spherically beIn order to study and diagnose the distribution, movement process and shape of the high-temperature plasma of pellet implosion in the Z-pinch implosion, a novel spherically bent crystal imaging system has been developed based on the Bragg diffraction theory. The key component of the imaging system is the spherically bent α-quartz crystal with the radius of 200 mm. An X-ray spectral imaging experiment using spherically bent α-quartz crystal has been carried out in the “Yang” accelerator in the Chinese Academy of Engineering Physics (CAEP). The X-ray film obtains the X-ray spectral information of Ti plasma. By analyzing the spectral information, the diagnostic result shows that the spectral resolution of the imaging system is 1092, which is consistent with theoretical value of the spectral resolution model. The imaging system meets the demand of spectral diagnosis..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 130004 (2015)
Thin Films
Effects of Annealing Time on the Structure and Optical Properties of Aluminum-Doped Zinc Oxide Thin Films
Hou Haihong, Zhang Tao, Wang Bin, and Liu Lu
Aluminum-doped Zinc Oxide (ZnO:Al, AZO) thin films are deposited on K9 glasses by the DC magnetron sputtering. The deposited samples are annealed under the condition of vacuum and 300℃. Effects of annealing time on the microstructure, surface topography and optical properties of AZO thin films are researched, respectivAluminum-doped Zinc Oxide (ZnO:Al, AZO) thin films are deposited on K9 glasses by the DC magnetron sputtering. The deposited samples are annealed under the condition of vacuum and 300℃. Effects of annealing time on the microstructure, surface topography and optical properties of AZO thin films are researched, respectively. Results show that the optimal annealing time is 2 h. AZO thin films deposited under this condition has a stronger (002) diffracting peak with the grain size of 17.2 nm, and the surface microstructure is smooth and compact. The average transmittance of the sample in the UV-Vis band is 93.47%, and the corresponding optical energy gap is 3.41 eV..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 131001 (2015)
Ultrafast Optics
Study on Controlling the Filament by Gradient Density Method
Song Zhenming, Zhao Han, Lin Yuxian, and Ni Xiaochang
The gradient pressure and temperature are unified into gradient density, the characteristics of femtosecond filamentation is investigated and the plasma channel in gases with gradient density is accompanied, the feasibility of gradient density method to enlarge the length of the filament and plasma channel is studied. The gradient pressure and temperature are unified into gradient density, the characteristics of femtosecond filamentation is investigated and the plasma channel in gases with gradient density is accompanied, the feasibility of gradient density method to enlarge the length of the filament and plasma channel is studied. Furthermore, the concept of ideal density curve is presented. The ideal shapes of gradient density under different conditions are calculated and analysized. The femtosecond pulses which propagate under the ideal gradient density curve can achieve the maximum spectra broadening and shorter pulses after compression while avoiding the muti-filament. It is found that the nature of intense femtosecond pulses propagation under the ideal density curve is in the condition of maintain constant n2Pc, to make the spot radius of the pulse at certain range in the long distance propagation, and to perform a self-guide while avoiding the self focusing or ionization..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 132002 (2015)
Vision, Color, and Visual Optics
Statistical Analysis of Monochromatic Aberrations in Chinese Eyes with Glaucoma or Diabetes Retinopathy
Xiao Fei, Dai Yun, Zhao Junlei, Zhao Haoxin, and Zhang Yudong
The diversity and uncertainty of ocular aberrations in abnormal eyes limit the usefulness of adaptive optics in clinical application. Aberrations are characterized in two populations of Chinese abnormal eyes, namely those with glaucoma and those with diabetes retinopathy. Furthermore, the impact of aberrations on retinThe diversity and uncertainty of ocular aberrations in abnormal eyes limit the usefulness of adaptive optics in clinical application. Aberrations are characterized in two populations of Chinese abnormal eyes, namely those with glaucoma and those with diabetes retinopathy. Furthermore, the impact of aberrations on retinal image quality and the requirements of wavefront correctors for aberration compensation are analyzed. The results show that higher-order aberrations of glaucoma eyes and diabetes retinopathy eyes are larger than what is typical in normal eyes, approximately 2.9 and 1.8 times respectively. To reach diffraction-limited imaging, correction of Zernike polynomials more than the 8th order is necessary for both glaucoma eyes and diabetes retinopathy eyes and the required corrector Strokes are over 39 μm and 14 μm, respectively. The results presented will help guide the development of wavefront correctors for clinical instrumentation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 133001 (2015)
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