Journals >Chinese Journal of Lasers
Contents
2014
Volume: 41 Issue s1
77 Article(s)
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Research Article
Debye Theory Analysis of the Scattering Intensity and Refractive Index Measurement for Glass Beads
Li Shuiyan, Li Dahai, Zhao Jiwen, E Kewei, Zhang Chong, Guo Donghua, and Wang Qionghua
When investigating the scattering intensity distribution produced by a glass bead which is illuminated by a collimated beam with single length, Debye theory can be used to simulate and discuss the scattering properties. It is found that the intensity distribution of the k-order rainbow recorded by a detector which is oWhen investigating the scattering intensity distribution produced by a glass bead which is illuminated by a collimated beam with single length, Debye theory can be used to simulate and discuss the scattering properties. It is found that the intensity distribution of the k-order rainbow recorded by a detector which is on the left of a spherical particle is the superposition of the diffracted rays, the external reflected rays and the k time internal reflected rays primarily. The intensity distribution of the k-order rainbow on the right of the spherical particle is the superposition of the diffracted rays, the transmitting rays and the k time internal reflected rays mostly. When the wavelength of incident light is constant, the refractive index of the glass beads will change the degrees of the minimum deviation angle in the scattered light intensity distribution on the detector, and their diameters have no effect on the position of minimum deviation angle. Experimentally, the scattered intensity distribution of the first and the second rainbows of the glass beads with different refractive indices and radius are analyzed, and are compared with the geometrical method, which agrees with the result of simulation in Debye theory. This result shows that the proposed assumptions are reasonable, which can be used to measure the refractive index of the glass beads through testing the minimum deviation angle formed by the light scattering..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 108010 (2014)
Research of a Dynamic Hartmann Sensor Using Liquid Crystal Spatial Light Modulator
Cai Dongmei, Ti Peipei, Jia Peng, Liu Jianxia, and Wei Hongyan
The micro-lens array is the core component of Shack-Hartmann wavefront sensor. According to the phase modulation principle of liquid crystal spatial light modulator (LC-SLM), the LC-SLM generates dynamic micro-lens array with tunable focal length, aperture size, and arrangement of sub-apertures. Hartmann wavefront sensThe micro-lens array is the core component of Shack-Hartmann wavefront sensor. According to the phase modulation principle of liquid crystal spatial light modulator (LC-SLM), the LC-SLM generates dynamic micro-lens array with tunable focal length, aperture size, and arrangement of sub-apertures. Hartmann wavefront sensor based LC-SLM is used to split the incident light. The average slope of each sub-aperture is tested. The phase distribution of wavefront is reconstructed. Then the wavefront aberration is corrected in one step. After aberration, the Strel ratio of the light wave changes from 0.12 to 0.59. For the micro-lens array generated by LC-SLM, heir focal length, adjacent spacing, numbers and performance are discussed in theory and experiment. The results show that the dynamic Hartmann sensor using LC-SLM has the advantages of tunable sub-aperture size, numbers and arrangement according to the external conditions..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 112001 (2014)
Impact of Observation Geometry on Lightning Optical Radiance Observed by Satellite
Hu Liqin, Zhao Haiying, and Ma Yanzhi
For the next generation of Chinese geostationary meteorological satellites (FY-4) an optical lightning mapping sensor is planned to observe lightning on a real-time, continual basis. The measurement will detect the radiance discharged by lightning and transferred up to the cloud top at a near-infrared band. One importaFor the next generation of Chinese geostationary meteorological satellites (FY-4) an optical lightning mapping sensor is planned to observe lightning on a real-time, continual basis. The measurement will detect the radiance discharged by lightning and transferred up to the cloud top at a near-infrared band. One important and urgent attention of the pre-study is how the instrument observation geometry quantitatively impact the received signals. A Monte Carlo approach is applied for simulating the transfer of lightning and the lightning radiation signatures which will be obtained by FY-4 lightning mapping sensor. The study focuses on the quantitative relationships between the observed lightning radiance and several key observation geometry parameters, such as satellite observation angle, pixel size and the horizontal location of lightning in the pixel. This will provide extremely valuable informations for the future application of lightning data observed by FY-4 satellite..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 113001 (2014)
Influences of the Atmospheric Turbulent Scales on the Scintillation Index of Reflector Echo
Wei Hongyan, Cheng Ling, Cai Dongmei, Ma Lin, Han Guoxia, and Zhang Hongjian
Corner reflectors on satellites are inevitably subjected to the influence of atmospheric turbulences in space explorations and tracking targets. Turbulence effects produce significant intensity fluctuations, seriously affecting the quality of the detected signal. In order to study the influences of atmospheric turbulenCorner reflectors on satellites are inevitably subjected to the influence of atmospheric turbulences in space explorations and tracking targets. Turbulence effects produce significant intensity fluctuations, seriously affecting the quality of the detected signal. In order to study the influences of atmospheric turbulent inner and outer scales on the scintillation index, researches about the corner reflector echo scintillation index from the transmitter to the reflector and from the reflector to the transmitter are carried on based on the ITU-R atmospheric structure constant model which is dependent on the altitude, while considering the influences of inner and outer scales. Numerical calculation results indicate that in the weak turbulence zone, inner scale turbulence scintillation indexes of the echo effects are greater than the outer scale; in the strong turbulence zone, with the outer scale increases, the echo scintillation index also increases, and it is larger than the inner scale..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 113002 (2014)
Simulation of Atmospheric Anisoplanatic Imaging Based on Kirchhoff Diffraction
[in Chinese], [in Chinese], and [in Chinese]
Atmospheric anisoplanatism is one of the key subjects for the wide field view high resolution imaging of telescope. The simulation of anisoplanatic imaging is the basis of the research on the restoration of the blurred image. The theoretical model of atmospheric anisoplanatic imaging based on the Kirchhoff diffraction Atmospheric anisoplanatism is one of the key subjects for the wide field view high resolution imaging of telescope. The simulation of anisoplanatic imaging is the basis of the research on the restoration of the blurred image. The theoretical model of atmospheric anisoplanatic imaging based on the Kirchhoff diffraction theory is set up. The atmospheric anisoplanatic effect can be expressed by multilayer phase screens. Light wave phase change of every dot on the object after atmosphere can be expressed by a phase screen, and phase size is the superposition of phases after each phase screen. The experiments are executed to test the proposed method, and finish the simulations of anisopalnatic imagings of starry, nebula, and moon craters. The experimental results show that the simulated image reflects the effect of atmospheric turbulence, diffraction and spatially variety on point spread function (PSF) from different field views. There is no ringing and edge effect in this anisoplanatic image..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 113003 (2014)
Optimization Design for Bi-Membrane Pressure Axial Adjusting Mechanism of Lithograph Objective
Sun Zhen, Zhang Defu, and Hua Yangyang
A bi-membrane axial adjusting mechanism is designed to meet the requirement of high precision and long distance in projection objective. The mechanism uses pressure for driving force. And optimization of different widths and thicknesses of diaphragms and width of the convex. It is optimized to gain the optimization parA bi-membrane axial adjusting mechanism is designed to meet the requirement of high precision and long distance in projection objective. The mechanism uses pressure for driving force. And optimization of different widths and thicknesses of diaphragms and width of the convex. It is optimized to gain the optimization parameters at certain pressure range. And then the frequency of mechanism is checked. The figure error of lens is analyzed to gain the Zernike coefficient when the mechanism is moving. The result indicates that the main figure error is power and sphere. The peak-to-valley (PV) of the low surface figure is better than 13.45 nm, and the root-mean-square (RMS) is better than 2.851 nm. The axial adjusting mechanism satisfies the requirement of lithograph projection objective..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 116001 (2014)
Optical Performance of CPCs Suitable for All-Glass Evacuated Tubes
Wang Jinfu, and Tang Runsheng
The angular dependence of optical efficiency of six compound parabolic concentrator (CPCs) suitable for concentrating radiation on all-glass evacuated tubes is investigated by ray-tracing method, and the annual radiation concentrating on unit length of solar tubes by means of six CPCs is estimated based on the angular The angular dependence of optical efficiency of six compound parabolic concentrator (CPCs) suitable for concentrating radiation on all-glass evacuated tubes is investigated by ray-tracing method, and the annual radiation concentrating on unit length of solar tubes by means of six CPCs is estimated based on the angular dependence of optical efficiency of CPCs and solar geometry. Results show that the optical efficiency of CPC designed by “hat-shaped” absorber with a V-groove at the bottom of reflectors is higher than that of other CPCs for the case of the incidence solar rays within the acceptance angle of full CPC, otherwise less than that of other CPCs. It is concluded that the CPC designed by “ice-cream shaped” absorber is the optimal design, and the one designed by the cover tube is the most inferior solution in terms of the annual radiation concentration on the solar tube..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 116002 (2014)
Design of Superachromatic Focusing Optical System for Wide Spectrum
Li Yuyao, Wang Fei, and Che Ying
When measuring the laser beam parameter, in order to solve the problem of different laser wavelengths have different focal positions for focusing optical system, simplify the measurement procedure and reduce the measurement error, the superachromatic focusing optical system for wide spectrum is designed. Based on the tWhen measuring the laser beam parameter, in order to solve the problem of different laser wavelengths have different focal positions for focusing optical system, simplify the measurement procedure and reduce the measurement error, the superachromatic focusing optical system for wide spectrum is designed. Based on the theory of wavefront chromatic aberration, the equations for the initial structure of the superachromatic system are derived. The superachromatic system is designed by the optical design software ZEMAX. It′s waveband is 350~1100 nm, the focal length is 250mm and the entrance pupil diameter is 25 mm. The longitudinal aberration and the focal shift curve of design results are given. Analysis shows that the spherical aberration curves of different wavelengths at 0.707 aperture intersect at one point approximately, which achieve the superachromatic. The focal shift in the working waveband is only 38.2 μm, and the focal plane position is fixed basically, which meets the measurement requirement of laser beam parameter from ultraviolet to near infrared..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 116004 (2014)
Opt-Mechanical System Design and Simulation of SBIRS GEO-1 a Geostationary Camera
Wang Wei, Chen Fansheng, Cui Kun, and Jiang Fanming
Space based infrared system (SBIRS) is an important part of American′s space defense system, the first of which is called SBIRS GEO-1, in geostationary orbit, launched in May 2011. GEO-1 provides infrared detective and missile warning etc. With high resolution and real-time observing in worldwide. An improved short-axiSpace based infrared system (SBIRS) is an important part of American′s space defense system, the first of which is called SBIRS GEO-1, in geostationary orbit, launched in May 2011. GEO-1 provides infrared detective and missile warning etc. With high resolution and real-time observing in worldwide. An improved short-axis Schmitt optical structure is designed and simulated based on the study of SBIRS GEO-1 opt-mechanical. Its image quality approaches diffraction limit, with average value of modulation transfer function (MTF) designed spectrum of 0.847 at the Nyquist frequency (14.3 lp/mm). Besides, the deployable outer sunshield servo system is demonstrated, the inhibitory effect of sun stray-light and external thermal flux are analyzed in different time. The results can meet system design requirements. The GEO-1 study provides a certain reference for the infrared imaging system development of our space exploration..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 116005 (2014)
Application of Acousto-Optic Tunable Technology on Palm Skin Spectral Imaging
Zhang Chunguang, Wang Hao, Gao Qiang, and Huang Junfeng
By the acousto-optic tunable filter (AOTF), the wavelength of the optical signal can be tuned fast in the wide spectral area. In the past study, the performance of the diffraction efficiency, the spectral resolution and the image stabilization is limit. It restricts the development of the AOTF on the spectral imaging aBy the acousto-optic tunable filter (AOTF), the wavelength of the optical signal can be tuned fast in the wide spectral area. In the past study, the performance of the diffraction efficiency, the spectral resolution and the image stabilization is limit. It restricts the development of the AOTF on the spectral imaging area. In this study, we introduce the self-design non-collinear AOTF as the spetroscopic element, and set up the spectral imaging system. Further more, we obtain the microscopic images and the corresponding spectra of the plam skin tissue. In the whole working waveband, the image definition and stabilization is well,and the spectral resolution keeps on the higher level. This study indicates the applicability of the AOTF on the spectral imaging. It provides a new technology for the development of the biomedicine microscopic spectral imaging..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 116006 (2014)
Study of Illumination Uniformity of LED Arrays for Radiation Calibration
Ye Zhao, Wang Chao, Cao Qipeng, and Zhu Jun
Illumination uniformity of LED arrays is studied through theoretical derivation and computing simulation. The spatial angle distribution and plane illuminance distribution are analyzed. A source model of LED arrays is designed based on the requirement of illumination uniformity of laboratory radiation calibration. The Illumination uniformity of LED arrays is studied through theoretical derivation and computing simulation. The spatial angle distribution and plane illuminance distribution are analyzed. A source model of LED arrays is designed based on the requirement of illumination uniformity of laboratory radiation calibration. The illumination uniformity of the model is simulated using LightTools. Simulation results show that the LED arrays′ irradiance uniformity is 98.3% and the spatial angle radiation uniformity is 98.2%. The Labsphere integrating sphere is tested and compared with simulation results. The simulation results are close to the test results of integrating sphere, which indicat that the designed LED arrays satisfy the requirement on source uniformity of laboratory radiation calibration..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 116007 (2014)
Design and Fabrication of Infrared Dichroic Beam Splitter
Wang Yijian, Wu Xiaoming, Li Xin, Liu Fengyu, and Tao Getao
In order to separate the spectrum, dichroic beam splitter has been widely used in various types of the optical system. Based on the infrared dichroic beam splitter of many-spectrum detect systems,the substrate and coating materials are analyzed. Ge and ZnS are chosen as coating materials and Ge as substrate. The initiaIn order to separate the spectrum, dichroic beam splitter has been widely used in various types of the optical system. Based on the infrared dichroic beam splitter of many-spectrum detect systems,the substrate and coating materials are analyzed. Ge and ZnS are chosen as coating materials and Ge as substrate. The initialization configuration of traditional long-wavelength pass filter is optimized by software,and optimum configuration is coated. The spectral performance and enviroment qualities of infrared dichroic beam splitter are tested. The results show that it meets the requirement of optical system. Such infrared dichroic beam splitter has been successfully applied to many-spectrum detect systems..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 116008 (2014)
Holography and Information Processing
Research on the Data Fidelity of Optical Compressive Spectral Imaging
Chen Yuheng, Ji Yiqun, Zhou Jiankang, Chen Xinhua, and Shen Weimin
The optical compressive spectral imaging method reconstructs the spectral data cube of the shooting scenery from acquired compressive image data, which has the features such as reducing acquisition data amount, realizing snapshot imaging for certain field of view, increasing signal-to-noise ratio and so on. Due to the The optical compressive spectral imaging method reconstructs the spectral data cube of the shooting scenery from acquired compressive image data, which has the features such as reducing acquisition data amount, realizing snapshot imaging for certain field of view, increasing signal-to-noise ratio and so on. Due to the mechanism restriction of compressive imaging, the reconstructed spectral data from the single compressive image suffer from fidelity attenuation, which leads to the decrease of the image quality and application ability. Based on the compressive sensing theory, the spatial coding optical compressive spectral imaging system model is developed and multi-frame shooting under variable spatial light modulation conditions is carried out so that high-fidelity cubic data is reconstructed from a certain number of compressive images with the support of optimization method. The AVIRIS imaging data is used to simulate the scenery so that the multi-frame spatial coding optical compressive spectral imaging simulation is carried out and the whole-spectral-region root-mean-square-error is adopted to evaluate the data fidelity quantitatively. The experimental results indicate that with the multi-frame shooting method the data fidelity improves, the imaging quality increases and the spectral curve deviation drops..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 109001 (2014)
A Fast Method of Unmanned Aerial Vehicle Carrier Landing Attitude Estimation Based on Feature Pattern
Zhuang Likui, Cao Yunfeng, Shi Yangyang, and Hu Yunqiang
Based on the demand of the unmanned aerial vehicle′s (UAV′s) autonomous landing, an easily identifiable pattern is designed. The image information is achieved by the camera in UAV, by using Harris algorithm to process corner detection to obtain the image coordinates of feature points, and matching them with the spatialBased on the demand of the unmanned aerial vehicle′s (UAV′s) autonomous landing, an easily identifiable pattern is designed. The image information is achieved by the camera in UAV, by using Harris algorithm to process corner detection to obtain the image coordinates of feature points, and matching them with the spatial coordinates of feature points. Orthogonal iteration algorithm is used to estimate the attitude of UAV. The algorithm is implementationed vision evaluation platform based on digital signal processor (DSP), and semi-physical simulation is conducted. Experimental results show that the method has higher calculation speed and accuracy, which providing a certain reterence to practical application..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 109002 (2014)
Multiscale Fusion of Wavelet-Domain Information and Clustering Analysis for Digital Halftoning
He Zifen, Zhang Yinhui, Zhan Zhaolin, and Wang Sen
A novel approach to improve the halftoning image quality by a mixture distortion criterion is the combination of a edge weighted least squares depending on the fusion multiscale information and the region weighted least squares depending on the improved K-means clustering method. The multiscale characterization of the A novel approach to improve the halftoning image quality by a mixture distortion criterion is the combination of a edge weighted least squares depending on the fusion multiscale information and the region weighted least squares depending on the improved K-means clustering method. The multiscale characterization of the original image using the discrete wavelet transform is obtained. The boundary information of the target image is fused by the wavelet coefficients of the correlation between wavelet transform layers, to increase the pixel resolution scale. The inter-scale fusion method to gain fusion coefficient of the fine-scale is applied, which takes into account the detail of the image and approximate information, where the fusion coefficient is referred to as the weighting operator, and to establish the boundary energy function. The improved K-means clustering method is used to segment an image several regions and the new energy function is constructed using the weighted least squares method, which the reciprocal of the variance of the segmented regions are referred to as the weighting operator to establish the region energy function. In the halftone process, each clustering uses the weighted least-squares method through energy minimization via direct binary search algorithm, to gain halftoning image. Simulation results on typical test images further confirm the performance of the new approach..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 109003 (2014)
Experiment Research of Lucky Imaging in Frequency Domain with Adaptive Optics Images
Ren Chengang, Liang Yonghui, Yu Qifeng, and Jiang Pengzhi
Lucky imaging is a post processing technique which can reconstruct a high resolution image for adaptive optics. In classic lucky imaging algorithm, only a few images which meet the image quality criterion are selected, shifted and added to reconstruct a final image, with image resolution reaching diffraction limited reLucky imaging is a post processing technique which can reconstruct a high resolution image for adaptive optics. In classic lucky imaging algorithm, only a few images which meet the image quality criterion are selected, shifted and added to reconstruct a final image, with image resolution reaching diffraction limited resolution of the large ground-based optical telescopes. However, high resolution information in given direction of the unselected images is rejected as a result. As to the lucky imaging in frequency domain algorithm, the information is selected in Fourier domain for every frame. It selects Fourier complex values with highest amplitude values at each spatial frequency below the cut-off frequency. Therefore, it makes a more efficient use of high resolution information contained in the short exposure images. Simulation results show that lucky imaging in frequency domain can overcome the effect of the atmosphere turbulence and improve the ability of the telescope. The results on real world astronomical images show that the lucky imaging in frequency domain often yields final image of better quality than classic lucky imaging algorithm at an equivalent selection ratio without an adaptive optics system..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 109004 (2014)
Color Images Feature Extracting Based on Visual Perception and Parameters Setting
Wang Mengjun, Yang Lu, Wang Xia, and Liu Jianfei
Optimal feature vector can be extracted in color image space. To acquire optimal parameters of pulse coupled neural network (PCNN) for color image space, color image processing are carried out by simulating visual perception of mammal. Entropy sequence of PCNN is calculated as feature vector to classify the traffic sigOptimal feature vector can be extracted in color image space. To acquire optimal parameters of pulse coupled neural network (PCNN) for color image space, color image processing are carried out by simulating visual perception of mammal. Entropy sequence of PCNN is calculated as feature vector to classify the traffic signs in RGB and HSV color space. Optimal parameters of PCNN are acquired through experiments. Experiments are carried out in GB5768-1999 of standard traffic signs image database. Experimental results show that the maximum inter-class distance value is acquired among 43 warning signs, 42 prohibition signs, and 29 instruction signs based on the entropy sequence of PCNN in blue color space while the optimal parameters of PCNN are αL=1, αF=0.1, αE=1, VL=0.2, VF=0.5, VE=27, β=0.1, and N=50 iterations. Blue component of the RGB model can fully reflect the color characteristics of traffic signs, entropy sequence of PCNN can be used as the vector sequences to distinguish three categories, superior to conventional color image into a grayscale image processing methods..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 109005 (2014)
Autonomous Underwater Vehicle Tracking Pipeline System Based on Optical Images
Wan Lei, Huang Shuling, Zhang Tiedong, and Zhang Qiang
Considering the issue of underwater pipeline recognition and tracking using autonomous underwater vehicle(AUV), the data flow is analyzed on the basis of simulation environment establishment, image processing, pipeline recognition and environment model. A complete underwater pipeline detecting and tracking system is prConsidering the issue of underwater pipeline recognition and tracking using autonomous underwater vehicle(AUV), the data flow is analyzed on the basis of simulation environment establishment, image processing, pipeline recognition and environment model. A complete underwater pipeline detecting and tracking system is proposed. In the process of pipeline recognition, to overcome the defect of line fitting using traditional Hough transform, an improved Hough transform is presented to dislodge the non-pipeline area in the view of feature clustering and to consider neighborhood of peak value process. Straight and curved pipelines are detected and tracked through the three-dimensional simulation environment for several times. Experiment results indicate that the presented system can effectively and autonomously detect and track pipelines with pipeline recognition and environment mapping..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 109006 (2014)
A High Dynamic Range Image Acquisition Method Based on the Multi-Exposure Imaging
Huang Sijie, and Liao Xingxing
An image acquisition method with 6 times exposure using a common imaging system is presented. A “gray value-radiance” model has been built through the imaging process analysis, and the image gray value of each pixel changing in the relationship with the integration time has been acquired, ending with a infused 10 bits An image acquisition method with 6 times exposure using a common imaging system is presented. A “gray value-radiance” model has been built through the imaging process analysis, and the image gray value of each pixel changing in the relationship with the integration time has been acquired, ending with a infused 10 bits image with all the 6 multiple exposure image sequences. Using this method, an image with all the details of the scene is synthesized, enhancing the image sensitivity, and exhibiting a demonstrable effect in the dark target detection with the highlighted surroundings..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 109007 (2014)
Multi-Scale Image Segmentation Based on Exact Inference of Hidden Markov Forest
Zhang Yinhui, and He Zifen
An exact inference approach of posterior probability is proposed for multiscale image segmentation to overcome limitation of local optimum as well as unbounded convergence rate of traditional wavelet-domain hidden Markov tree (HMT) segmentation methods. Hidden Markov forest (HMF) model is constructed by characterizing An exact inference approach of posterior probability is proposed for multiscale image segmentation to overcome limitation of local optimum as well as unbounded convergence rate of traditional wavelet-domain hidden Markov tree (HMT) segmentation methods. Hidden Markov forest (HMF) model is constructed by characterizing inter-scale statistical dependence between fine scale pixel and high scale wavelet coefficients. Bottom-up likelihood estimation and up-bottom posterior inference on each sub-tree of the HMF model are performed, in which consistency of unary and pairwise distribution is guaranteed. Binary segmentation at multiscales are achieved by threshold the posterior probability. Experimental results of typical dynamic background segmentation as well as comparison with segmentation by weighted aggregation (SWA) algorithm demonstrate the effectiveness of our method..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 109008 (2014)
A High Dynamic Range Fusion Method Based on Multi-Exposure Imaging
Huang Sijie, Chen Fansheng, and Liao Xingxing
Multi-exposure image fusion aims to integrate complementary information of each exposure image to form a new image with the scene information more comprehensively, accurately and reliably. The main methods in image fusion are irradiance reconstruction method, pyramidal transform wavelet transform method, HIS feigned muMulti-exposure image fusion aims to integrate complementary information of each exposure image to form a new image with the scene information more comprehensively, accurately and reliably. The main methods in image fusion are irradiance reconstruction method, pyramidal transform wavelet transform method, HIS feigned multicolor method and so on. These methods effectively enhance the detectable target brightness range, but among most of them, the large dynamic range of the scene information is mapped to 8 bit, which indeed increases the luminance information of the underexposed and overexposed scene areas, but at the expense of the contrast of the intermediate luminance. A multi-exposure fusion method is presented, using 4 exponential integral times in a fixed scene for image capture. The unsaturated zone is matched through multiplying the low dynamic range image sequence by a integration time factor images directly. All the images are fused with the contrast being the weighting factor, ultimately, a 11 bit image with rich details and distinct levels is captured..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 109009 (2014)
Comparisons of Restoration Methods on Two-Dimensional Reconstructed Images of THz In-Line Digital Hologram
Li Qi, Hu Jiaqi, and Yang Yongfa
The reconstructed image noises of THz in-line digital hologram are higher, especially the background noises, which seriously affect the overall effect of the image. To realize image smoothing, this paper proposes the restoration methods on two-dimensional reconstructed images of THz Gabor in-line digital hologram by coThe reconstructed image noises of THz in-line digital hologram are higher, especially the background noises, which seriously affect the overall effect of the image. To realize image smoothing, this paper proposes the restoration methods on two-dimensional reconstructed images of THz Gabor in-line digital hologram by combining opening-closing-by-reconstruction in mathematical morphology with non-local means or median non-local means filter. Digital processing and comparative analysis for the real reconstructed image of the target with lower resolution are carried out. The images processing results show that the proposed composite algorithm can remove most of the noise, leading to image smoothing and signal-to-noise ratio improvement, and the effect is obviously better than seperately using any one single filter in composite algorithm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 109010 (2014)
Remote Sensing Image Segmentation Based on Minimum Class Mean Absolute Deviation
Yang Xuye, Li Aoxue, Xu Shuaijing, and Zhang Libao
Otsu method and its improved methods are widely suitable for the images whose histograms belong to Gauss distribution. However, they perform poor when the histograms of images belong to a mixture of other distributions. An algorithm based on the minimum class mean absolute deviation (MCMAD) is proposed. The new algoritOtsu method and its improved methods are widely suitable for the images whose histograms belong to Gauss distribution. However, they perform poor when the histograms of images belong to a mixture of other distributions. An algorithm based on the minimum class mean absolute deviation (MCMAD) is proposed. The new algorithm transforms two-dimension histogram into one-dimension histogram to decrease the computation complexity by diagonal projection method. The new proposed algorithm calculates the class mean and the class probability of every threshold in one-dimension histogram. The new proposed algorithm gets the minimum class mean absolute deviation of different thresholds by traversing all the thresholds in the one-dimension histogram. Among these thresholds, the threshold corresponding to the minimum class mean absolute deviation is the best segmentation threshold. Experimental results show that the new proposed algorithm not only can segment well on remote sensing images with histograms belonging to normal distribution, but also improve the performance of the remote sensing images with histograms belonging to Laplace distribution comparing with traditional Otsu method and its improved methods. Furthermore, the time consuming of the new proposed algorithm is low..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 109011 (2014)
Laser Manufacturing
Effect of Process Parameters on the Residual Stress in Laser Additive Manufacturing
Lai Youbin, Liu Weijun, Zhao Jibin, Zhao Yuhui, and Wang Fuyu
In order to study the effect of different process parameters on the residual stress in laser additive manufacturing, 10 test samples are made with different process parameters by the special laser additive manufacturing system with TA15 alloy material. Cross sectiions of specimens are all 24 mm×40 mm square. UsingIn order to study the effect of different process parameters on the residual stress in laser additive manufacturing, 10 test samples are made with different process parameters by the special laser additive manufacturing system with TA15 alloy material. Cross sectiions of specimens are all 24 mm×40 mm square. Using the indentation stress measurement method to measure the residual stress of sample, laser power density and powder flow density on the residual stress in laser additive manufacturing are studied. The results show that the residual stress in the laser additive manufacturing is significantly less than the yield strength. The residual stress is positively correlated with the laser specific energy and laser power density, and is negatively correlated with the powder flow density..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 103001 (2014)
Rust Removal and Uniform Passivation Simultaneously in Laser Wet Cleaning Using Dual Laser Beam
Li Wei, Du Peng, and Song Feng
Pulsed CO2 laser is used in the wet laser cleaning of rust from iron surface. By pre-spraying liquid film to the top surface, the liquid can penetrate into the rust layer due to the porous structure of the rust, so the thermal conductance and the mean specific heat of the rust layer can be improved. At the mean time, aPulsed CO2 laser is used in the wet laser cleaning of rust from iron surface. By pre-spraying liquid film to the top surface, the liquid can penetrate into the rust layer due to the porous structure of the rust, so the thermal conductance and the mean specific heat of the rust layer can be improved. At the mean time, as the explosive evaporation of the liquid in the rust under laser irradiation has the effect of breaking down the rust layer, the cleaning efficiency can be efficiently increased. But it is disadvantageous that the electro-chemical corrosion of the iron will be intensified if the liquid film has some residue. Thus, the removal of the residual liquid film is a necessary operation after the first-step of cleaning. Acousto-optic Q-switched NdYAG laser is used to heat the iron surface. By adjusting the number of laser pulse, the surface temperature can be controlled. The residual liquid film is vaporized firstly, and then the oxidation process of the superficial iron layer can be accelerated. A dense film of iron oxide is formed above the iron surface. Uniform passivation is realized and the corrosion resistance of the iron is modified after laser cleaning. A device of laser wet cleaning adopting dual laser beam is designed, which can perform cleaning and passivating simultaneously..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 103002 (2014)
Ultra-Narrow Gap High Power Fiber Laser Beam Welding of Stainless Steel Heavy Section with Filler Wire
Zhang Guowei, and Xiao Rongshi
The effects of welding parameters such as spot diameter, gap width, laser power and welding speed on the joint formation of ultra-narrow gap laser beam welding with filler wire are studied by using IPG YLS-6000 fiber laser and defocused beam. Results show that when the spot diameter is wider than gap width and leading The effects of welding parameters such as spot diameter, gap width, laser power and welding speed on the joint formation of ultra-narrow gap laser beam welding with filler wire are studied by using IPG YLS-6000 fiber laser and defocused beam. Results show that when the spot diameter is wider than gap width and leading filler wire and filler wire melting in molten pool are used, the joint formation in heat conduction welding model is the best; smaller spot diameter leads to and larger spot diameter leads to pores, excessive fusion of sidewalls. Under the same welding conditions, the greater the gap width, the narrower range of welding process windows for welded joints without defects will be. As the gap width increases, the suitable laser power is increased, and the welding speed is reduced. Small heat input can produce lack of fusion on sidewall, and larger heat input can cause keyhole induced pores. Under the optimized parameters, 60 mm thick stainless steel plates are welded by less than 5 mm ultra-narrow-gap laser welding with filler wire, and a complete defects free butt joint which consists of 20 layers is obtained. The width of weld is uniform and only about 3.8 mm, and the angular distortion of the joint is about 0.6°..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 103003 (2014)
Laser Physics
Vectorial Structure Characteristics of Anomalous Hollow Vortex Beams in the Far Field
Tang Bihua, Luo Yamei, Gao Zenghui, and Zheng Shangbin
Based on the methods of vector angular spectrum and stationary phase, the analytical expressions of the TE and TM terms and energy flux distributions of anomalous hollow vortex beams in the far field are derived and used to analyze the phase singularities and energy flux distributions. It is shown that under certain coBased on the methods of vector angular spectrum and stationary phase, the analytical expressions of the TE and TM terms and energy flux distributions of anomalous hollow vortex beams in the far field are derived and used to analyze the phase singularities and energy flux distributions. It is shown that under certain conditions elliptical (or circular) edge dislocation, straight edge dislocation or optical vortices will appear in the light field. By changing the vortex off-axis distance or waist width, the phase singularities will vary. The position of black nucleus, symmetry and elliptical dark ring of the energy flux distributions are dependent on the vortex off-axis distance..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 102001 (2014)
Theoretical Analysis of Quasi-Bessel Beam for Laser Micromachining
Wu Pinghui, and Huang Wenhua
A quasi-Bessel beam can propagate over a long distance with its beam width unchanged, which provides a high beam aspect ratio, and is suitable for laser micromachining of structures. The propagation properties of quasi-Bessel beam generated by the ideal axicon and blunt-tip axicon are investigated. Strong peak oscillatA quasi-Bessel beam can propagate over a long distance with its beam width unchanged, which provides a high beam aspect ratio, and is suitable for laser micromachining of structures. The propagation properties of quasi-Bessel beam generated by the ideal axicon and blunt-tip axicon are investigated. Strong peak oscillations occur due to interference between the quasi-Bessel beam and the refracted beam by the blunt-tip. Using the axicon for laser micromachining is theoretically calculated. Simple analytical formulas can be used to predict the required parameters, including laser pulse energy, generated fluence distribution, ablation width, beam aspect ratio and so on..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 102002 (2014)
Q-Switching and Mode-Locking of Er-Doped Fiber Lasers Based on Tm-Ho Codoped Fiber
Tao Mengmeng, Yi Xisheng, Wang Ping, Wang Zhenbao, Yang Pengling, and Feng Guobin
Exploiting Tm-Ho codoped fiber as the saturable absorber, stable passive Q-switching and mode-locking of an Er-doped fiber ring laser is achieved. In the Q-switching operation mode, the repetition rate is tunable with pump power from several kHz to tens of kHz at 1567.8 nm, and the pulse duration is at the μs level. WiExploiting Tm-Ho codoped fiber as the saturable absorber, stable passive Q-switching and mode-locking of an Er-doped fiber ring laser is achieved. In the Q-switching operation mode, the repetition rate is tunable with pump power from several kHz to tens of kHz at 1567.8 nm, and the pulse duration is at the μs level. With polarization control, Q-switched mode-locking operation is observed at 1535.2 nm. Further increasing the pump power and tuning the polarization controller, mode-locking is achieved with repetition rate of tens of MHz and pulse duration of tens of ns. With even higher pump power, 2nd order rational harmonic mode locking is obtained. The experiments demonstrate that Tm-Ho codoped fiber is an excellent saturable absorber for all fiber passive Q-switching and mode-locking of Er-doped fiber lasers..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 102003 (2014)
Propagation Properties of Orthogonally Polarized Double Gaussian Beams in Nonlocal Pannar Waveguides
Chen Rongquan, Wang Xinghua, Xu Zhiyong, and Li Dongbo
The propagation rules of double orthogonal polarization and coinciding centre Gaussian beams which propagate in nonlocal nonlinear planar waveguides are studied with analytical method. The evolution equations of two beam various parameters and two critical powers are obtained, the values of which relate to the couplingThe propagation rules of double orthogonal polarization and coinciding centre Gaussian beams which propagate in nonlocal nonlinear planar waveguides are studied with analytical method. The evolution equations of two beam various parameters and two critical powers are obtained, the values of which relate to the coupling coefficient and the degree of nonlocality. In the case of the unique refraction, the critical powers of two beams are the same when the initial beam widths are equal to each other. When the initial power equals the critical power, two orthogonal polarization Gaussian linear spatial solitons are derived, which are irrelevant with the degree of nonlocality of the medium. For the strongly nonlocal case, under the condition of unique refraction, the analytical evolution expressions of various parameters of beams are obtained. When the total power is equal to the critical power, and the two beam powers are not the same, two orthogonal polarization Gaussian types of breathers are obtained, the higher power beam width compressing oscillates periodically and the lower power beam width broadening oscillates periodically..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 102004 (2014)
A Narrow-Line-Width Multi-Wavelength Erbium-Doped Fiber Laser Based on Arrayed-Waveguide Grating and Optical Circulator
Liu Zhiming, Chen Kunfeng, Gao Yesheng, and Jian Shuisheng
A novel multi-wavelength erbium-doped fiber laser with narrow-line-width lasing output is proposed and demonstrated using arrayed-waveguide grating (AWG) and optical circulator (OC). Wavelength competition and consistency are naturally prevented in this kind of laser by using AWG as comb filter and OC as completely refA novel multi-wavelength erbium-doped fiber laser with narrow-line-width lasing output is proposed and demonstrated using arrayed-waveguide grating (AWG) and optical circulator (OC). Wavelength competition and consistency are naturally prevented in this kind of laser by using AWG as comb filter and OC as completely reflecting mirror in the linear-cavity. As an example, a dual-wavelength erbium-doped fiber laser is experimentally investigated. Using the laser scheme, the proposed laser can generate two wavelengths simultaneously. The fiber laser realizes the optical side-mode suppression ratio of over 50 dB and the average output power of -9.7 dBm and -9.6 dBm at 1554.872 nm and 1555.671 nm, respectively. The full width at half maximum (FWHM) of the spectrum of each laser is less than 0.010 nm. Moreover, the output power stability of the laser has also been measured and analyzed. Experiment results show that the laser can operate in stable narrow-line-width with dual-wavelength output at room temperature..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 102005 (2014)
Research on the Characteristics of the Optical Element Damage Caused by Surface Pollution
Yin Xianhua, Zhuang Yifei, Zhang Yan, and Zhang Guowen
By using a tuning Q NdYAG laser with an output laser wavelength of 1064 nm, this article focuses on the systematic research on surface damage situation in optical glass caused by impurities in different irradiation ways. On the basis of a determined zero probability in damage threshold within K9 glass and fused silica By using a tuning Q NdYAG laser with an output laser wavelength of 1064 nm, this article focuses on the systematic research on surface damage situation in optical glass caused by impurities in different irradiation ways. On the basis of a determined zero probability in damage threshold within K9 glass and fused silica component substrate, this article proposes experiments on damage characteristics in metal particle pollutants and organic pollutants, analyzes the inducing mechanism of decreased damage threshold caused by surface pollutants..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 102006 (2014)
Research on Generating and Application in the 266 nm Ultraviolet Standard Wavelength
Wang Shaoshui, Zhu Xingbang, Sun Quanshe, and Zhang Facai
As the atomic lines power of atomic spectrum light is weak and wavelength cannot trace to notional standard, this paper introduces a development technology of standard wavelength source at 266 nm. Using second harmonic generation and fourth harmonic genemtion technique, the laser beams at 532 nm and 266 nm are obtainedAs the atomic lines power of atomic spectrum light is weak and wavelength cannot trace to notional standard, this paper introduces a development technology of standard wavelength source at 266 nm. Using second harmonic generation and fourth harmonic genemtion technique, the laser beams at 532 nm and 266 nm are obtained which based on 1064 nm single solid-state ring laser. Using modulation transfer spectroscopy, the frequency of the 532 nm laser is stabilized at a10 hyperfine spectra of 127I2 R(56)32-0. Laser beam at 266 nm is obtained from frequency stabilization laser beam at 532 nm using external circular frequency doubling technology. The 532 nm laser is traced back to femtosecond laser based optical frequency comb apparatus in National Institute of Metrology, and this indirectly realizes the quantity traceability at 266 nm wavelength. The experiment results prove that the Allan variance of standard ultraviolet wavelength source at 266 nm is less than 1×10-10. The ultraviolet spectrograph corrected by wavelength standard has fine wavelength precision..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 102007 (2014)
Optimization Design of Laser Diode Pumped Rubidium Vapor Laser for High Output Power
Zhao Xiaohong, Wang Shihong, Liu Wanfa, and Tan Yannan
The diode pumped alkali rubidium laser is investigated by the three level rate equations for improving the laser output power of diode pumped alkali vapor laser (DPAL). The systemic conditions are considered, including pump power, pump bandwidth, gain medium cell temperature and length. The simulation results are essenThe diode pumped alkali rubidium laser is investigated by the three level rate equations for improving the laser output power of diode pumped alkali vapor laser (DPAL). The systemic conditions are considered, including pump power, pump bandwidth, gain medium cell temperature and length. The simulation results are essentially coincident with the existing experiment results. Furthermore, we put forward the optimal design parameters of gain cell for high output power and optical-optical conversion efficiency with a definite pump condition..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 102008 (2014)
Investigation of Double the Optical Angular Multiplexing System for “Heaven” Facility
Xiang Yihuai, Gao Zhixing, Tang Xiuzhang, Sandor Szatmari, and Bohus Janos
The “Heaven” facility is the maximal high power krypton-fluoride (KrF) excimer laser in our country. It is composed of an excellent beam profile amplified spontaneous emission (ASE) source, a discharge pumped KrF laser, two stage two-electron-pumped KrF amplifiers, six beams optical angular multiplexing system for beamThe “Heaven” facility is the maximal high power krypton-fluoride (KrF) excimer laser in our country. It is composed of an excellent beam profile amplified spontaneous emission (ASE) source, a discharge pumped KrF laser, two stage two-electron-pumped KrF amplifiers, six beams optical angular multiplexing system for beam smoothing, physical diagnostic system, etc. The facility can produce six beams, more than one hundred joule energy, 248 nm wavelength, 23 ns width laser pulse. This paper introduces a method and technology research of double the optical angular multiplexing system for “Heaven” facility. The main contents are as followed: the method of producing 10 ns pulse, the principle introduce of polarization beam split,and the design scheme of twelve beams angular multiplexing system..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 102009 (2014)
Materials and Thin Films
Flexible Nano Metal-grid Transparent Electrode and Its Application
Liu Haiyan, Zhang Weiguo, Zhou Xiuli, and Shi Haofei
Flexible transparent electrode has attracted wide attentions from researchers due to its lightweight, flexibility, low-costing, and can be widely used in optoelectronic devices in the future such as flat panel displays, solar cells and touch panels.The Ag-grid transparent electrode is prepared by photolithography, the Flexible transparent electrode has attracted wide attentions from researchers due to its lightweight, flexibility, low-costing, and can be widely used in optoelectronic devices in the future such as flat panel displays, solar cells and touch panels.The Ag-grid transparent electrode is prepared by photolithography, the transmittance within the visible range(400～800 nm) is greater than 90.48% regardless of substrate,the sheet resistance can be low to 4.1 Ω/sq, and the transparent electrode has a high σDC/σOP and good flexibility,when bending 1000 times the sheet resistance only change 11.8%, and it is applied to 4 inches (1 inch=2.54 cm) flexible resistive touch screen by screen printing,demonstrating the uniformity and reliability of the transparent electrode..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 106001 (2014)
Frequency-Dependent Signal Blind Area “Cavity” in Multi-Layer Optical Waveguide
Yao Guozheng, and Liu Ying
Because the size of photonic device is close to the size of optical wavelength，photonic circuit shows significant diffractive characteristics, which can be used to design photonic devices with novel function. To realize the similar “skin effect” of electronic circuit, we utilize the similarity between “Schrdinger EquaBecause the size of photonic device is close to the size of optical wavelength，photonic circuit shows significant diffractive characteristics, which can be used to design photonic devices with novel function. To realize the similar “skin effect” of electronic circuit, we utilize the similarity between “Schrdinger Equation” and the wave function in inhomogeneous medium, and design a type of multi-layer cylindrical optical waveguide with high gradient refractive index and pseudo-gravity potential index distribution. Simulation shows high frequency signal propagate in the surface layer, and signal blind area (“cavity”) exists in the inner part of the waveguide. The size of the cavity varies with the wavelength of the light. The boundary of the cavity locates near the inner-boundary of the layers. Longer wave is less affected by the discontinuity, and can penetrate further into the inner material. The domain of the cavity decreases with the wavelength. This result may have significance for the design of “perfect invisible cloak” and new type photonic circuit..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 106002 (2014)
Electronic and Optical Properties of Rutile TiO2 Co-Doped with Nitrogen and Platinum Group Metals (Ru,Rh,Pd)
Zhu Hongqiang, Feng Qing, and Yue Yuanxia
The change is optical properties and the extention of the application in the field of photocatalysis and photoelectric conversion of the metal and nonmetal-co-doped TiO2 are heatedly studied in recent years. The properties of band structure, density of states, optical properties and defect formation energy of rutile TiThe change is optical properties and the extention of the application in the field of photocatalysis and photoelectric conversion of the metal and nonmetal-co-doped TiO2 are heatedly studied in recent years. The properties of band structure, density of states, optical properties and defect formation energy of rutile TiO2 super-cell with metallic and nonmetallic impurity co-doped with N-Ru, N-Rh and N-Pd are calculated by plane wave pseudopotential method based on the density functional theory. The results show that rutile TiO2 co-doped with N, N-Ru, N-Rh and N-Pd improve the visible light absorption and utilization efficiency. The defect formation energies decrease in the order of N-Pd, N-Rh and N-Ru, which shows that N-Ru is the most easily doped into TiO2 lattice in co-doped condition. TiO2 co-doped with N-Rh greatly improves absorptivity and reflectivity and achieves the best effect in the range of visible light wavelength..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 106003 (2014)
Non-Collinear Quasi-Phase Matching Harmonics in Nonlinear Photonic Crystals with Highly Symmetrical Superlattices
Ma Boqin, Liu Rongjuan, Chen Baoqin, and Li Zhiyuan
By using quasi-phase matching technology, series of non-collinear harmonic pairs in more than five laser wave bands are realized in one piece of LiNbO3 nonlinear photonic crystal with two-dimensional dodecagonal superlattices when the laser wavelengths vary from 930 nm to 1307 nm. With the input fundamental wavelength By using quasi-phase matching technology, series of non-collinear harmonic pairs in more than five laser wave bands are realized in one piece of LiNbO3 nonlinear photonic crystal with two-dimensional dodecagonal superlattices when the laser wavelengths vary from 930 nm to 1307 nm. With the input fundamental wavelength decreasing from 1118.8 nm by nearly 52 nm, a pair of non-collinear green harmonics always exist except for one collinear harmonic for 1081.4 nm. More than three pairs of yellow harmonics appear on the screen at the input wavelength 1234.5 nm. The distance between pairs of red harmonics increases from 3.5 mm to 5.5 mm with input beam changing from 1306.1 nm to 1302.6 nm and the non-collinear harmonic spots look like triangles..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 106004 (2014)
Theoretical and Experimental Investigation of Thermal Barrier Coatings for Laser Proof
Zhang Lei, Ma Zhuang, Yang Pengling, Wu Yong, Yan Zhenyu, and Lu Lin
Along with the fast development of high power lasers, the corresponding measuring techniques should be improved to withstand the long time irradiation of high power density laser beams. An aluminum panel is coated with ZrO2 thermal barrier coatings (TBCs) using plasma spraying method as the high power laser proof. DiffAlong with the fast development of high power lasers, the corresponding measuring techniques should be improved to withstand the long time irradiation of high power density laser beams. An aluminum panel is coated with ZrO2 thermal barrier coatings (TBCs) using plasma spraying method as the high power laser proof. Diffuse reflection characteristics of the coating are investigated at different wavelengths. Finite element analysis is conducted to analyze the thermal response of the ZrO2 TBCs under the high power laser irradiation. Moreover, related experiments are carried out with high power fiber lasers, which demonstrat that the TBCs is an effective method for heat insulation..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 106005 (2014)
Impact of Structure Design of Photonic Crystals on LED Light Extraction Efficiency
Shen Xiaoxia, Cai Lüzhong, Dong Guoyan, and Ren Yazhou
Two light emitting diode (LED) structures such as the introducing of AlGaN confining layer and the embedded photonic crystal (PC) LED are proposed to improve the light extraction efficiency of PC LEDs. The distributions of guided modes propagated in LED are analyzed, and the modal extraction lengths are calculated usinTwo light emitting diode (LED) structures such as the introducing of AlGaN confining layer and the embedded photonic crystal (PC) LED are proposed to improve the light extraction efficiency of PC LEDs. The distributions of guided modes propagated in LED are analyzed, and the modal extraction lengths are calculated using high-resolution angle-resolved measurements in order to research the interaction of each guided mode with PCs. The impact of structure parameters design on modal extraction length is considered. The result shows that the introduction of an AlGaN confining layer in LEDs is effective in extracting a fraction of the optical energy of low order modes, but this approach is limited by the growth of the lattice mismatched AlGaN layer on GaN. And embedded PC LEDs have superior extraction of the guided light due to spatially overlapped with all guide modes which have the higher interaction between all optical modes..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 106006 (2014)
POSS Modified Polylactic Acid Film
Gu Wenjuan, He Zifen, and Zhang Xiaohui
POSS-NH3Cl is introduced to polylactic acid (PLLA) by blending and grafting separately to improve the properties of PLLA, especially the transparency. A series of star-shaped polylactic acid is synthesized using L-lactic acid (L-LA) and octa (γ-chloroammoniumpropyl) octasilsesquioxane (POSS-NH3Cl) in the presence of stPOSS-NH3Cl is introduced to polylactic acid (PLLA) by blending and grafting separately to improve the properties of PLLA, especially the transparency. A series of star-shaped polylactic acid is synthesized using L-lactic acid (L-LA) and octa (γ-chloroammoniumpropyl) octasilsesquioxane (POSS-NH3Cl) in the presence of stannous (II) octanoate [Sn(Otc)2] catalyst, and the mechanism is studied. Meanwhile, a series of composite cross-linked films are prepared by casting. The structures of these dendritic polymers are characterized by Fourier transform infrared spectra (FTIR), which conforms the presence of the grafting reaction at the same time. Ultraviolet (UV)-visible light transmittance analyzer is used to analyze the transparency of the composite films. It is found that polyethylene glycol (PEG) has little relation to the transparency of the film while the content of POSS-NH3Cl affected the transparency. The grafted products exhibit superior transparent property than blend ones due to better compatibility with the PLLA. The transparency of the film improves even 40% in some wavelength, which is explained theoretically..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 106007 (2014)
Surface Damage Features of Sapphire by Nanosecond Laser Irradiation
Chen Lizi, Xiang Zhen, Jing Chunyuan, Guan Xiaowei, and Li Yan
Laser-induced damage morphology using nanosecond laser pulses on sapphire surfaces is reported. The temperature variation of sapphire inclusion (Cu) under different laser fluence irradiations is analyzed, and the temperature variation of inclusion′s dimension radius is simulated by finite element method. The laser-induLaser-induced damage morphology using nanosecond laser pulses on sapphire surfaces is reported. The temperature variation of sapphire inclusion (Cu) under different laser fluence irradiations is analyzed, and the temperature variation of inclusion′s dimension radius is simulated by finite element method. The laser-induced damage experiment of two sapphires with different sizes are investigated by 6 ns pulse width, 1064 nm laser. At the same time, the sapphire laser-induced damage threshold, damage position distribution, influence of different laser fluences on the damage area and damage growth characteristics are analyzed. Results show that the inclusion absorption mechanisms can preferably explain the sapphire damage under the nanosecond laser pulse irradiation, and simulation results are in agreement with the experimental results. In addition, with the 1-on-1 irradiation, sapphire surface damage area gets larger with the increase of laser fluence linearly, while with the s-on-1 irradiation, the damage area on the back surface exponentialy grows with laser shot number..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 106008 (2014)
Measurement and Metrology
Research on the Measurement Methods for the Gain Distribution Uniformity of Large Aperture Slab Amplifiers
Hao Xin, Chen Lin, Chen Yuanbin, Liu Jianguo, Liu Yong, Zhao Junpu, Liang Yue, Tang Jun, Li Sen, and Chen Dehuai
Utilizing the scientific charge-coupled device (CCD) and Hartmann test system, the gain distribution uniformity of large aperture slab amplifiers is measured on the integration test bed and processing methods are put forward for these two methods. The effects of various measuring methods and post-processing methods on Utilizing the scientific charge-coupled device (CCD) and Hartmann test system, the gain distribution uniformity of large aperture slab amplifiers is measured on the integration test bed and processing methods are put forward for these two methods. The effects of various measuring methods and post-processing methods on gain uniformity are compared in detail by numerical calculation and analysis. The results show that the measuring randomness can be avoided and spatial noise of gain distribution can be minimized when measuring the gain uniformity by the scientific CCD with multi-shot averaging smoothed method. The results also show that less lattice number reduces the gain roll-off at the edges of the aperture when measuring the gain uniformity by Hartmann, which indicates a lattice number of over 50×50 is proposed..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 108001 (2014)
Phase-Shifting Plane Imaging VISAR with High Temporal Resolution
Liu Shouxian, Chen Guanghua, Peng Qixian, Lei Jiangbo, Yuan Shuyun, Liu Jun, Deng Xiangyang, and Li Zeren
In order to overcome the deficiencies of framing plane imaging velocity interferometer system for any reflector (VISAR),a simultaneous phase-shifting plane imaging VISAR with high temporal resolution is developed. With the double interferometers arrangement, fringes can be produced in VISAR with an ultrashort laser pulIn order to overcome the deficiencies of framing plane imaging velocity interferometer system for any reflector (VISAR),a simultaneous phase-shifting plane imaging VISAR with high temporal resolution is developed. With the double interferometers arrangement, fringes can be produced in VISAR with an ultrashort laser pulse. As a substitute for polarizing beamsplitters, Wollaston prisms are used to produce four spatial phase shift interferograms. Then, geometric correction of interferograms is done using space transformation. At last, a push-pull signal processing method is used to obtain the phase and velocities. Full-field velocity map is provided with a temporal resolution of 150 ps and a velocity sensitivity of 6 m/s. The technique is employed to measure a two-dimensional spatial velocity field of Al foils flyer driven by a pulse laser. These experimental results demonstrate the feasibility of the new imaging VISAR..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 108002 (2014)
Experimental Study on Laser Active Illumination to Space Targets within the Shadow of Earth
Zhang Haifeng, Zhang Zhongping, Qin Si, Li Pu, Wu Zhibo, and Yu Yong
Low earth orbit space targets is more impressionable to the shadow of earth, which makes the ground optical observation system unable to realize the optical observation and posts the influences on the optical measurement data. As the active detection technology, laser active illumination is to use laser track and obserLow earth orbit space targets is more impressionable to the shadow of earth, which makes the ground optical observation system unable to realize the optical observation and posts the influences on the optical measurement data. As the active detection technology, laser active illumination is to use laser track and observation system on ground and transmit the laser beam to space targets within the shadow of earth. The receiving telescope and charge coupled devices (CCD) camera on ground receive and detect the laser echoes from targets and obtain the images if the requirements of CCD detecting threshold is meet. The laser signal with 532 nm wavelength is adopted as the light sources and the observations of laser active illumination to artificial satellites with the retro-reflectors within the shadow of earth are successfully implemented to validate the feasibility of measurement technology. According to the parameters of laser track and observation system on ground, the theoretical analysis of the signal noise ratio of CCD and the magnitude of illuminated satellites are also performed. Based on the image processing method of gray correlation, the measured magnitude of laser illumination to satellites is obtained and compared to the results of theoretical calculation, which verifies the rationality of theoretical and experimental methods..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 108003 (2014)
Measurement of Phase Delay of Two-Dimensional Distribution Characteristics of Liquid Crystal Electro-Optic Devices
Qi Mingchun, Huang Ziqiang, Yao Zhoushi, Tan Qinggui, and Wang Xiangru
Based on the Senamont method, a method of testing the two-dimensional (2D) distribution of phase delay is presented. The 2D distribution of phase delay of liquid crystal optical wedge and OA-LC-SLM is measured.The results we have measured is reported. The 2D phase distribution characteristic curve of the liquid crystalBased on the Senamont method, a method of testing the two-dimensional (2D) distribution of phase delay is presented. The 2D distribution of phase delay of liquid crystal optical wedge and OA-LC-SLM is measured.The results we have measured is reported. The 2D phase distribution characteristic curve of the liquid crystal optical wedge is calculated by writting a program.The results show that the apex angle of the liquid crystal optical wedge adds when the testing voltage increasing. In the same way, the 2D phase contour map of the OA-LC-SLM is calculated. The 2D phase distribution of the OA-LC-SLM is analyzed..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 108004 (2014)
Experiment of Laser Ranging to Space Debris Based on High Power Solid-State Laser System at 200 Hz Repetition Rate
Zhang Zhongping, Zhang Haifeng, Wu Zhibo, Li Pu, Meng Wendong, Chen Juping, and Pang Yu
Space debris becomes vital factors threatening the safety of working spacecrafts on orbit. The laser ranging technology will play an important role in precise measuring orbits, accurate cataloging, surveillance and forewarning to space debris. Based on the laser link equation, the analysis of laser echo signal detectioSpace debris becomes vital factors threatening the safety of working spacecrafts on orbit. The laser ranging technology will play an important role in precise measuring orbits, accurate cataloging, surveillance and forewarning to space debris. Based on the laser link equation, the analysis of laser echo signal detection from different power lasers with different working frequencies is performed. The 50 W power diode pumped solid-state laser system with 200 Hz repetition rate is applied to observe space debris. Combining with the low dark noise detector, range gate generator with the nanosecond controlling precision and high efficient spectral filter, the measurement to space debris with high success rate are realized. Among the measured targets, the minimum cross section is about 0.5 m2 and the farthest distance is more than 2100 km. The results show that the laser ranging system has good performance while using the high power, high repetition rate laser and verify the feasibility of high repetition rate, low pulse energy laser to observe space debris. The results are helpful for the development and application of space debris laser ranging technology with high repetition rate in the future..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 108005 (2014)
Research on Aspheric Testing Based on Off-Axis Computer-Generated Hologram
Ma Yun, Gao Zhishan, Zhu Rihong, and Ma Jun
Using null lens such as computer-generated hologram (CGH) is almost the routine for testing asphere at present. The using of on-axis CGH has many advantages, but the central area of the asphere can not be tested due to the ghost. In this paper, a new program is proposed, where the influence of ghost is eliminated by usUsing null lens such as computer-generated hologram (CGH) is almost the routine for testing asphere at present. The using of on-axis CGH has many advantages, but the central area of the asphere can not be tested due to the ghost. In this paper, a new program is proposed, where the influence of ghost is eliminated by using off-axis CGH and modified Twyman-Green interference setup. In this program, the off-axis CGH is placed on the imaging arm, compensating the testing wavefront secondly and separating the varied diffraction orders in the direction of vertical axis. With the tilt axis and filter, 0th order of the reference wavefront and -1st order of the testing wavefront are adopted to get interferograms which are used to carry out the aspherical testing. In our proposed program, the asphericity is compensated with the combination of standard spherical lenses and off-axis CGH. For comparison, the same asphere is tested by on-axis CGH with Zygo interferometer. The experimental results confirm that the ghost image is eliminated successfully, the results of the two tests keep well agreement, and this program can be used to test large aperture asphere on high accuracy..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 108006 (2014)
Processing Method Research for Multi-Pulse Measured Data of High Repetition Frequency Laser Ranging
Li Zhulian, Zheng Xiangming, Fu Honglin, He Shaohui, and Xiong Yaoheng
The data processing method for multi-pulse measured data in high frequency laser ranging is analyzed and researched, and a useful method is got by measuring pulse interval time using ground target ranging, adjusting transmitting epoch, screen processing and etc. Applied to process ranging data from 1.2 m telescope highThe data processing method for multi-pulse measured data in high frequency laser ranging is analyzed and researched, and a useful method is got by measuring pulse interval time using ground target ranging, adjusting transmitting epoch, screen processing and etc. Applied to process ranging data from 1.2 m telescope high frequency laser ranging system, it indicates efficient data increasing 10% at least, and root mean square hardly changing. This is significant to middle and high orbit satellites laser ranging data process where the echo signal is a few but there is muti-pulse measured data phenomenon..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 108007 (2014)
Investigation and Application of Laser-EMAT Testing Fatigue Damage of Railhead
Zhao Yang, Liu Shuai, Ma Jian, Sun Jihua, Song Jiangfeng, Guo Rui, and Jia Zhongqing
The objective of the study is to provide a novel method and system that is used to inspect the fatigue defects of the rail in a non-contact way. A laser-electro magnetic acoustic transducer (EMAT) system is designed in Laser Institute of Shandong Academy of Sciences, which is used in the present work. Artificial surfacThe objective of the study is to provide a novel method and system that is used to inspect the fatigue defects of the rail in a non-contact way. A laser-electro magnetic acoustic transducer (EMAT) system is designed in Laser Institute of Shandong Academy of Sciences, which is used in the present work. Artificial surface cracks and holes with different sizes are prepared on the rail. The principle of mode conversion is applied to determine the defects above. Namely, Rayleigh wave generated by line laser source becomes shear wave when the Rayleigh wave passes the surface defect. To receive the defect signal in a noncontact way, an EMAT sensor is used in this work. Experimental results show that the amplitude of defect signal increases with the increase of defect depth. To avoid the influence of noise on the testing result, the ultrasonic signal of surface defect is processed by wavelet soft-threshold filter designed by Matlab. The signal to noise ratio increases by 12 dB at least. The results show that the laser-EMAT technique has good prospects in the engineering applications of rail testing..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 108008 (2014)
Radiation Calibration of CCD Applied to Dimensional Measurement
Liu Jun, Zuo Yong, and Zhao Jing
In order to improve the accuracy of non-contact imaging measurement, it is rather essential for people to identify the radiation calibration of charge-coupled device (CCD). This article explains the theory and necessity of radiation calibration in the field of non-contact imaging measurement through an experiment in whIn order to improve the accuracy of non-contact imaging measurement, it is rather essential for people to identify the radiation calibration of charge-coupled device (CCD). This article explains the theory and necessity of radiation calibration in the field of non-contact imaging measurement through an experiment in which the quantitative relationship between the radiation intensity of illumination at the surface of CCD and the digital of gray value is built, resulting in the penalty function of the camera. Consequently, the radiation calibration of CCD has been accomplished within the limits of the prescriptive uncertainty..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 108009 (2014)
Optical Communication
Energy Efficiency Research of Optical Burst Switching Networks
Yang Jiuru, Liu Chunyu, Chang Jinlong, and Ding Qun
Optical burst switching (OBS) with the nature of optical bypass is one of the potential techniques for future green optical internet. Due to the fact that main operations perform at edge nodes, the energy efficiency of OBS is directly affected by parameters setting, but it has been rarely reported to date. In the articOptical burst switching (OBS) with the nature of optical bypass is one of the potential techniques for future green optical internet. Due to the fact that main operations perform at edge nodes, the energy efficiency of OBS is directly affected by parameters setting, but it has been rarely reported to date. In the article, based on low power idle (LPI), the transition of burst is comprehensively analyzed and the quantitative energy model is established. Further, the energy efficiencies of extra offset time (EOT) and fixed assembly size (FAS) are compared under the target loss probability. The numerical results show that, with LPI model, EOT is superior to FAS in energy consumption because a 48.86% saving is gained..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 105001 (2014)
Multi-Wavelength Fiber Ring Laser Based on Mach-Zehnder Interferometer of Dispersion Compensation Fiber Connection Point
Wang Jishun, Yu Yongqin, Ou Zhilong, Huang Quandong, Chen Xue, Yan Peiguang, and Du Chenlin
Stable multi-wavelength lasing based on in-fiber Mach-Zehnder interferometer (MZI) introduced by dispersion compensation fiber (DCF) in an erbium-doped fiber ring laser is presented. This interference effect effectively suppresses the unstable mode competition caused by homogeneous line broadening which leads to the geStable multi-wavelength lasing based on in-fiber Mach-Zehnder interferometer (MZI) introduced by dispersion compensation fiber (DCF) in an erbium-doped fiber ring laser is presented. This interference effect effectively suppresses the unstable mode competition caused by homogeneous line broadening which leads to the generation of stable multi-wavelength lasing at room temperature. The dual-wavelength lasing is so stable and the peak fluctuation is less than about 1.1 dB, while the peak fluctuation of the tri-wavelength lasing is much larger with a value of about 4 dB..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 105002 (2014)
Analyses of Noise on the Four-Wave-Mixing Effect in Micro-Nano Waveguides
Zhang Xiantao, Yan Lianshan, Guo Yinghui, Wang Lujun, Pan Wei, and Luo Bin
Optical logics can be achieved by utilizing four-wave-mixing (FWM) effects in micro-nano waveguides. We analyze the contributions of signal noise onto the efficiency of FWM in such nonlinear waveguides. Since Gaussian noise exists extensively in most practical systems, we analyze the FWM process of the input signals, wOptical logics can be achieved by utilizing four-wave-mixing (FWM) effects in micro-nano waveguides. We analyze the contributions of signal noise onto the efficiency of FWM in such nonlinear waveguides. Since Gaussian noise exists extensively in most practical systems, we analyze the FWM process of the input signals, which are affected by amplitude noise, frequency noise, phase noise and additive noise in the metal-insulator-metal (MIM) waveguides. Results show that, with the average power of the phase noise increasing over 1.44, the normalization intensity of the idle light generated in the FWM process is less than -40 dB, compared to -18 dB without noise, indicating a significantly reduction of nonlinear efficiency. However, if the signals are affected by other kinds of noise, the intensity of the idle light is nearly the same as that without noise. Therefore, FWM process in such waveguides is sensitive to Gaussian phase noise, while it′s not sensitive to other kinds of noise..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 105003 (2014)
Filter Characteristics of a Sinc-Shaped Surface Plasmonic Filter in the Visible Light Band
Zhang Gaofeng, Yang Rongcao, and Xue Wenrui
With two dimensional finite-difference time-domain (2D-FDTD) method, filter characteristics of a Sinc-shaped surface plasmonic filter are studied in the visible light band. The results show that, each transmission curve exists in a wide forbidden band, the position of the forbidden band is affected significantly by theWith two dimensional finite-difference time-domain (2D-FDTD) method, filter characteristics of a Sinc-shaped surface plasmonic filter are studied in the visible light band. The results show that, each transmission curve exists in a wide forbidden band, the position of the forbidden band is affected significantly by the height of the Sinc function, the maximum groove depth and the groove width, and weakly by the half-width of the main petal, the period of the slots and the horizontal groove width of the channel. Compared with 1.55 μm band, the width of the forbidden band is more narrow, and both sides of the passband band also are lower. This work would provide a theoretical reference for the design, production and application of surface plasma filters..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 105004 (2014)
Novel Performance Estimation for QPSK Signals Impaired by Narrow Filtering
Zhu Yupeng, Yang Yanfu, Yan Bingyang, Zhong Jiechang, Cao Jianchao, and Yao Yong
A new algorithm of error vector magnitude (EVM) for quadrature phase shift keying (QPSK) signals impaired by narrow filtering is proposed theoretically in this paper. The new algorithm can remove the influence of intersymbol interference (ISI) induced by filtering, so the calculated EVM can be utilized for accurate estA new algorithm of error vector magnitude (EVM) for quadrature phase shift keying (QPSK) signals impaired by narrow filtering is proposed theoretically in this paper. The new algorithm can remove the influence of intersymbol interference (ISI) induced by filtering, so the calculated EVM can be utilized for accurate estimation on optical signal to noise ratio and bit error rate. The numerical results also confirmed that the proposed scheme has better estimation accuracy on optical signal to noise ratio, and the modified algorithm taking into account the ISI-induced distortion can improve the estimation accuracy of bit error rate. Meanwhile, the interference-related symbol number is discussed for trade-off between computation efficiency and estimation performance, and the estimation performance is analyzed under different system conditions, including optical signal to noise and filter bandwidth..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 105005 (2014)
Study on Performance Test of Communication Network
Yang Song, Zhao Donghe, Xi Lixia, and Zhang Xiaoguang
Due to lots of mixed traffic existing in the actual situation and the processing performance of the product limited by many factors, the performance test of communication network can generally meet the laboratory requirements, while fail to meet the actual requirements of customers. In order to evaluate the actual procDue to lots of mixed traffic existing in the actual situation and the processing performance of the product limited by many factors, the performance test of communication network can generally meet the laboratory requirements, while fail to meet the actual requirements of customers. In order to evaluate the actual processing capability of the network node, a test model of performance is created. Moreover, analysis and the experimental verification of the test evaluation of the primary parameters, including throughput, mixed packet forwarding capacity, the rate of new connections, etc, of the network node are given..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 105006 (2014)
Raman Scattering Enhancement Characteristic of Hf-Doped Silica Fiber
Yan Faming, Chen Zhenyi, Chen Na, Guo Qiang, Wang Tingyun, and Sun Qingqing
Stimulated Raman scattering is one of the most important problems in the field of nonlinear fiber optics. The Raman scattering enhancement characteristic of Hf-doped silica fiber and Hf/Al co-doped silica fiber are researched. The Raman spectra of Hf-doped silica fiber and Hf/Al co-doped silica fiber are measured by usStimulated Raman scattering is one of the most important problems in the field of nonlinear fiber optics. The Raman scattering enhancement characteristic of Hf-doped silica fiber and Hf/Al co-doped silica fiber are researched. The Raman spectra of Hf-doped silica fiber and Hf/Al co-doped silica fiber are measured by using 785 nm exciting light, and compared with conventional single-mode fiber (SMF). The experimental results show that Hafnium doping or Hafnium/Aluminum co-doping can enhance the optical fiber Raman scattering intensity, and achieve a good Raman scattering enhancement effect..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 105007 (2014)
Relationship between Inter-Symbol-Transition Pattern and Optical Filtering Performance for Multi-Level PSK Modulator Implementations
Yan Bingyang, Yang Yanfu, Zhong Jiechang, Zhu Yupeng, Cao Jianchao, and Yao Yong
The inter-symbol-transition (IST) patterns of multi-level non-return-to-zero phase-shift-keying (NRZ-PSK) signals generated by two kinds of optical modulator implementations are analyzed to reveal the underlying relationship between IST patterns and optical filtering performance. In the tandem modulator implementationsThe inter-symbol-transition (IST) patterns of multi-level non-return-to-zero phase-shift-keying (NRZ-PSK) signals generated by two kinds of optical modulator implementations are analyzed to reveal the underlying relationship between IST patterns and optical filtering performance. In the tandem modulator implementations, some IST patterns are curved, and in the parallel implementations, all IST patterns are inherently straight lines. It′s proved that these IST patterns characteristics play a significant role in determining optical filtering performance. In the tandem implementations, optical filtering can lead to obvious IST pattern dependent signal distortion. As a comparison, the parallel implementations have less filtering-induced eye-opening penalty and consequently better tolerance against narrow filtering. Finally, the receiver sensitivity as a function of optical filter bandwidth for differential optical detection is studied together with the optimization of the demodulator parameter..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 105008 (2014)
Chromatic Dispersion Dynamic Monitoring and Compensation Based in Peak to Average Power Ratio for Coherent Optical Communication Receiving System
Zhang Wei, Xi Lixia, Zhao Donghe, Zhang Zhaomin, Bai Shunchang, Tang Xianfeng, and Zhang Xiaoguang
Chromatic dispersion (CD) dynamic monitoring and compensation technique by using peak to average power ratio (PAPR) to as a feedback is used in coherent communication system , and this method is insensitive for pattern, polarization mode dispersion and polarization dependent loss. Because the smallest PAPR typically coChromatic dispersion (CD) dynamic monitoring and compensation technique by using peak to average power ratio (PAPR) to as a feedback is used in coherent communication system , and this method is insensitive for pattern, polarization mode dispersion and polarization dependent loss. Because the smallest PAPR typically corresponds to the CD that results in the best performance, PAPR is used as feedback signal. We search PAPR minimum through direct search and two step search algorithms in frequency compensation. CD compensation value is the accumulated value in the link. The average errors of two methods to monitor CD are 312 ps/nm and 226 ps/nm. Therefore two search algorithm has lower complexity, and higher sensitivity..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 105009 (2014)
Response of Fiber Bragg Grating Fabry-Perot Cavity to Pulsed Laser Injection
Chen Haiyan, Chen Cong, Chen Lilin, Wang Meng, Li Qi, and Huang Kaiqiang
Cavity ring-down (CRD) spectrum of fiber Bragg grating Fabry-Perot (FBG-FP) cavity is researched theoretically. The expression of output light intensity of FBG-FP cavity is derived, and the effect of the power reflectance of FBG-FP cavity on CRD spectrum is discussed. Numerical results show that the output performance Cavity ring-down (CRD) spectrum of fiber Bragg grating Fabry-Perot (FBG-FP) cavity is researched theoretically. The expression of output light intensity of FBG-FP cavity is derived, and the effect of the power reflectance of FBG-FP cavity on CRD spectrum is discussed. Numerical results show that the output performance of FBG-FP cavity includes three phases: build-up, stability and ring-down phase. The light intensity in the cavity and CRD time of cavity are proportional to the power reflectance of the FBG-FP cavity. Finally, the response of FBG-FP cavity to injected laser pulse is experimentally demonstrated. Experimental results are consistent with the theoretical analysis..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 105010 (2014)
Expanding Measurement Range for Chromatic Dispersion Estimation Using Auto-Correlation of Signal Power Waveform
Zhang Wei, Xi Lixia, Li Jianrui, Tang Xianfeng, and Zhang Xiaoguang
By using auto-correlation of signal power waveform (ACSPW) for coherent systems, an improved method for chromatic dispersion (CD) estimation is proposed. In order to overcome the limitation of ACSPW, the ACSPW scheme is extended by artificially adding CD to the received signal using a finite impulse response filter in By using auto-correlation of signal power waveform (ACSPW) for coherent systems, an improved method for chromatic dispersion (CD) estimation is proposed. In order to overcome the limitation of ACSPW, the ACSPW scheme is extended by artificially adding CD to the received signal using a finite impulse response filter in the estimation phase, moving the pulse to the range that can be measured, and finally subtracting the known added value after the estimation. This method will be essentially unaffected by amplified spontaneous emission noise, pulse shapes and polarization mode dispersion. Mean error of monitoring results is 127 ps/nm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 105011 (2014)
Electrically Control Characteristics of Liquid Crystal Filled Photonic Crystal Fiber
Luo Caixiu, and Xie Yingmao
Based on the electrically control characteristics of liquid crystal, the band-gap of an perfect two-dimensional photonic crystal which is composed of triangular lattice circular air holes, the spectrum of liquid crystal 5CB filled photonic crystal fiber for different angles θ which are between the direction of externalBased on the electrically control characteristics of liquid crystal, the band-gap of an perfect two-dimensional photonic crystal which is composed of triangular lattice circular air holes, the spectrum of liquid crystal 5CB filled photonic crystal fiber for different angles θ which are between the direction of external electric field and x-axis, and the optical field distributions when the wave source wavelength is 2504 nm and different defect modes wavelength are numerically calculated by finite-difference time-domain (FDTD) and perfectly matched layer (PML). The results show as follow: the band-gap of an perfect two-dimensional photonic crystal ranges from 2335 nm to 2438 nm; the defect modes move to short-wave with the increasing of the angle θ, and the maximum value of regulation is 73 nm when the angle θ ranges from 0° to 90°; the light energy will not localize at the fiber core when the wave source wavelength is not within the band-gap limits; the light energy will localize at the fiber core when the wave source wavelength corresponds to different defect modes wavelength, and its distribution is more homogeneous with the increment of the angle θ..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 105012 (2014)
Refractive Index Sensor Based on Waist-Enlarged Tapers and Singlemode-Multimode-Singlemode Fiber Structure
An Jiali, Jin Yongxing, Sun Mingming, and Dong Xinyong
A fiber refractive index sensor based on the combination of waist-enlarged tapers and singlemode-multimode-singlemode (SMS) fiber structure is demonstrated. A 18 mm multi-mode fiber (MMF) is spliced with waist-enlarged taper between two conventional single-de fibers (SMFs) to construct an all-fiber sensor. The effectivA fiber refractive index sensor based on the combination of waist-enlarged tapers and singlemode-multimode-singlemode (SMS) fiber structure is demonstrated. A 18 mm multi-mode fiber (MMF) is spliced with waist-enlarged taper between two conventional single-de fibers (SMFs) to construct an all-fiber sensor. The effective refractive index of the cladding modes changes with the external refractive index. It shows that the sensitivity of the refractive index sensor is 152.237 nm/RIU (RIU is refractive index unit) in the refractive range index from 1.3725 to 1.4620. The temperature cross sensitivity of the refractive index sensor is 2.6×10-4 RIU/℃, so when the temperature changes little, the temperature impact on the refractive index measurement can be ignored. The presented refractive sensor is with simple manufacture and relatively low cost, so it has great potential for biological and chemical applications..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 105013 (2014)
100 Gb/s High Sensitivity Coherent Optical Communication System
Zhang Zhang, Yang Ning, Xu Junbo, Li Ling, and Hong Yingming
A digital signal processing, infradyne, polarization multiplex quartered phase-shift keying ultra high sensitivity coherent optical communication system is reported in this paper. The transmission bit-rate is 127 Gb/s and the payload bit-rate is 99.53 Gb/s. Sensitivity of -38.2 dBm is achieved in real-time back to backA digital signal processing, infradyne, polarization multiplex quartered phase-shift keying ultra high sensitivity coherent optical communication system is reported in this paper. The transmission bit-rate is 127 Gb/s and the payload bit-rate is 99.53 Gb/s. Sensitivity of -38.2 dBm is achieved in real-time back to back transmission. In this system, commercial devices are widely used and the design follows ITU-T recommendation. Therefore, the system has great prospects of application..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 105014 (2014)
Influence of Saturation Effect on the Optical Signal Group Velocity in Fiber Optical Parametric Amplifier
Gui Lin, Shao Yufeng, Zhou Zhibin, and Yu huimin
In fiber optical parametric amplifier, the nonlinear index induced by four-wave mixing effect varies with the frequency owing to the interaction between the strong pump wave and signal wave so that the group velocity of optical wave slows down or accelerates. Based on the analysis of parameters in the process of index In fiber optical parametric amplifier, the nonlinear index induced by four-wave mixing effect varies with the frequency owing to the interaction between the strong pump wave and signal wave so that the group velocity of optical wave slows down or accelerates. Based on the analysis of parameters in the process of index change induced by the four-wave mixing in fiber, the influence of saturation effect of pump wave on the delay time of signal wave is investigated. By solving the nonlinear equation based on Runge-Kutta method, the results of analytical method and numerical method are compared when low power and high power signal waves are injected into the fiber, and the region with large difference is obtained. This region is located in the band edge of the spectrum of fiber optical parametric amplifier. These results are conductive to know the slow and fast light phenomenon in fiber optical parametric amplifier..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 105016 (2014)
Rapid Communications
A Calibration Equipment of Responsivity Non-Unmiformity for Charge Coupled Devices
Liu Hongyuan, Wang Hengfei, Ma Shumin, Ying Chengping, Wu Bin, and Wang Hongchao
A method of calibrating responsivity nonunmiformity for visible charge coupled devices (CCD) is presented, and the measurement uncertainty for the calibration equipment is evaluated. The expanded uncertainty of responsivity non-unmiformity for visible CCD is 0.46%, and the output diameter of the radiation adjustable unA method of calibrating responsivity nonunmiformity for visible charge coupled devices (CCD) is presented, and the measurement uncertainty for the calibration equipment is evaluated. The expanded uncertainty of responsivity non-unmiformity for visible CCD is 0.46%, and the output diameter of the radiation adjustable uniform light source is 200 mm. The measurement uncertainty of the calibration equipment is verified use CCD, the measurement repeatability of the CCD is 0.003% and 0.005% less than 0.23% of the total uncertainty. The measurement repeatability of calibration equipment is reasonable. The calibration equipment can meet the calibration demand for big area array image device, meanwhile can provides a very useful reference for big area array image device factory and customers..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 116003 (2014)
Remote Sensing and Sensor
Super-Resolution Reconstruction Algorithm Based on Relevance Vector Machine for Hyperspectral Image
Wang Xiaofei, Yan Qiujing, Zhang Junping, and Wang Aihua
In order to improve the space resolution of hyper-spectral image by fusing the spatial information of multispectral images and the spectral information of hyperspectral images, a hyperspectral image super-resolution algorithm based on relevance vector machine (RVM) is proposed. A brief introduction of the principle of In order to improve the space resolution of hyper-spectral image by fusing the spatial information of multispectral images and the spectral information of hyperspectral images, a hyperspectral image super-resolution algorithm based on relevance vector machine (RVM) is proposed. A brief introduction of the principle of the Price method which fuses multispectral and hyperspectral images to get the super-resolution image is given, and the RVM linear regression is introduced. Combining with the advantages of RVM in regression analysis, a resolution enhancement by revealing the corrspondence of the spatial and spectral information is gotten. The experiment results show that the normalized root-mean-square (RMS) is lower than 0.001 and the spectral angel error is lower than 0.02, which gets a great improvement compared with the results of the Price method and the Elbakary method. The method proposed has a significant result in hyperspectral image reconstruction, which provides a much properer data source for classification, object detection and recognition..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 114001 (2014)
Study on the Geometric Characteristics of Micro-Seam Stitching Detectors
Gong Xueyi, Chen Fansheng, Su Xiaofeng, Huang Sijie, and Liu Qiang
The geometric parameters acquisition of splice detector is the most important thing to validate and evaluate the success of splice, but there is no systematic approach to solve it. For the rotation between the two detectors, the translation of the vertical slit, the slit width and other geometric parameters, the methodThe geometric parameters acquisition of splice detector is the most important thing to validate and evaluate the success of splice, but there is no systematic approach to solve it. For the rotation between the two detectors, the translation of the vertical slit, the slit width and other geometric parameters, the method based on imaging can give very accurate results. On the other hand, the smart-scope can give us the actual mean width of detector splicing, and the results are similar to the above. It proves that the method based on imaging can complete various geometric parameters tests with a very high precision. It just meets the needs of easy and high precision of the aerospace application, and it can provide powerful technical support for the detector slit splicing..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 114002 (2014)
Target Detection for Hyperspectral Image Based on Support Vector Data Description
Wang Xiaofei, Zhang Junping, Yan Qiujing, and Chi Yaobin
Hyperspectral imagery target detection has an important theoretical research value and application prospect, and it is a hot topic in the field of the remote sensing information processing. At present, most detection algorithms need to set an appropriate decision threshold, which is set by hand or computed by using theHyperspectral imagery target detection has an important theoretical research value and application prospect, and it is a hot topic in the field of the remote sensing information processing. At present, most detection algorithms need to set an appropriate decision threshold, which is set by hand or computed by using the objects and background information. In practice, the little prior knowledge of the background often limits the application of many algorithms. To solve this problem, a new pure-pixel target detection algorithm for hyperspectral image is presented, which is based on the support vector data description (SVDD). Then the target detection problem is transformed to one-class classification problem. Firstly, SVDD classifier is trained by selected samples, and then the data are classified into inner-class (the target) and outer-class (the background). Next, the spatial characteristics of the target are used to reduce false alarm rate of the classified image. Finally, the ultimate detection results can be obtained. Experimental results of the hyperspectral data show that compared with the two classical spectral angle mapping and constrained energy minimization methods, the proposed method, which only requires a small number of target training samples, can reach the close results as the two algorithms when the optimal threshold values are selected. When the background samples increase, the method is superior to the mentioned two algorithms..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 114003 (2014)
Analysis of Effect on Image Quality of TDICCD During Dynamic Imaging
Han Xingzi
Agile satellite can point to any interested place very deftly and fast, improving observe range and time efficiency of mission greatly. Most agile satellite take pictures either along satellite track or parallel with satellite track. Imaging parameter and imaging quality of change time delay and integration charge coupAgile satellite can point to any interested place very deftly and fast, improving observe range and time efficiency of mission greatly. Most agile satellite take pictures either along satellite track or parallel with satellite track. Imaging parameter and imaging quality of change time delay and integration charge coupled devices (TDICCD) during dynamic imaging process are analysed, error effects on image quality are given, and simulation result of main parameters change is acquired, in the end satellite control method is proposed..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 114004 (2014)
Spectroscopy
Study of π/n Optical Code Division Multiple Access En/Decoders Based on Equivalent Phase Shift
Zhu Huatao, Pu Tao, Zheng Jilin, Fang Tao, and Chen Yinfang
Improving the code capacity is a key of optical code division multiple access (OCDMA) system, and the usual method is to search for new code structure. We propose a novel way to facture π/n equivalent phase shift (EPS) OCDMA en/decoders without studying the code structure. The method only changes the physical structureImproving the code capacity is a key of optical code division multiple access (OCDMA) system, and the usual method is to search for new code structure. We propose a novel way to facture π/n equivalent phase shift (EPS) OCDMA en/decoders without studying the code structure. The method only changes the physical structure of fiber grating and can enhance the soft-capacity for 5 times. Based on the fiber grating fabrication plot we fabric π/5- and 2π/5-EPS en/decoders. The results of simulation and experiment show the π/n-EPS en/decoders can get better performance than the ordinarily one..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 105015 (2014)
Study of Capsicum Frutescens L. by Fourier Transform Infrared Spectroscopy
Li Weixing, Zhao Xingxiang, Liu Gang, Wang Xiaohua, and Wang Xiaolong
Fourier transform infrared spectroscopy (FTIR) combined with principal component analysis (PCA) and hierarchical cluster analysis (HCA) is used to study different kinds of capsicum frutescens L.. FTIR spectra of 50 samples are obtained from five species of capsicum frutescens L.. The results show that the infrared specFourier transform infrared spectroscopy (FTIR) combined with principal component analysis (PCA) and hierarchical cluster analysis (HCA) is used to study different kinds of capsicum frutescens L.. FTIR spectra of 50 samples are obtained from five species of capsicum frutescens L.. The results show that the infrared spectra of capsicum frutescens L. are similar, but tiny differences in wave-numbers and absorption intensities of peaks are observed in the range of 1800~800 cm-1. PCA and HCA are performed on the second derivative infrared spectra in this range. FTIR spectroscopy is found to be efficient in classification of capsicum frutescens L.. 50 samples are well divided into five groups and about 100% classification accuracy for HCA, about 98% accuracy for PCA are yielded. It is proved that FTIR combined with statistical analysis can be used to discriminate capsicum frutescens L...
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 115001 (2014)
Study of Different Tree Peony Varieties by Fourier Transform Infrared Spectroscopy
Zhao Shuaiqun, Liu Gang, Ou Quanhong, Zhao Xingxiang, Ren Jing, Xu Juan, and Hao Jianming
The conventional method to identify tree peony varieties is based on morphology, which is strongly subjective and lacks chemical information. Fourier transform infrared spectroscopy (FTIR) technology combined with principal component analysis (PCA) is applied to identify different varieties of tree peony flowers in thiThe conventional method to identify tree peony varieties is based on morphology, which is strongly subjective and lacks chemical information. Fourier transform infrared spectroscopy (FTIR) technology combined with principal component analysis (PCA) is applied to identify different varieties of tree peony flowers in this paper. The infrared spectra of tree peony samples are similar on the whole, which are mainly composed of the vibration absorption bands of proteins, phenols, lipids, glycosides, polysaccharides, flavonoids, and so on. First derivative sepctra in the range of 1800~700 cm-1 are selected to perform principal component analysis and correlation analysis using Matlab 2010 program. Correct classification amounting for 96% is observed. The results of principal component analysis and correlation analysis are identical with each other. It is demonstrated that FTIR-principal component analysis can be used as a possible means for the identification of different tree peony varieties..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 115002 (2014)
Infrared Spectroscopy Combined with LDA and BPNN Based on Wavelet Transform to Detect Citrus Osbeck Anthracnose
Zhao Xingxiang, Liu Gang, Li Weixing, Hao Jianming, Zhou Xiangping, and Wang Xiaohua
Fourier transform infrared (FTIR) spectroscopy combined with linear discriminant analysis (LDA) and back propagation neural network (BPNN) based on wavelet transform (WT) is applied to study citrus osbeck anthracnose and healthy peel. Continuous wavelet transform (CWT) is implemented to the FTIR spectra of anthracnose Fourier transform infrared (FTIR) spectroscopy combined with linear discriminant analysis (LDA) and back propagation neural network (BPNN) based on wavelet transform (WT) is applied to study citrus osbeck anthracnose and healthy peel. Continuous wavelet transform (CWT) is implemented to the FTIR spectra of anthracnose and healthy peel. By comparison, the decomposition level 10 is obviously different and proposed to extract feature vectors, then three feature regions of level 10 are used to train LDA and BPNN models. The performance of LDA algorithm is better than BPNN. On the other hand, in order to extrude the differences between anthracnose and healthy peel, discrete wavelet transform (DWT) is used to compose all spectra in 1750~950 cm-1 range. Wavelet transform approximation coefficients (DWTAC) and discrete wavelet transform detail coefficients (DWTDC) of level 5 are used to train LDA and BPNN models. Results show that accuracy of both LDA and BPNN based on DWTDC (95%) is better than DWTAC. LDA and BPNN algorithms based on wavelet transform can be successfully used for identifying citrus osbeck anthracnose and healthy peel with FTIR spectroscopy. It also provides technology support to detect citrus anthracnose in early stage quickly and effectively..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 115003 (2014)
Design and Simulation of Bubble Scattering Micro-Spectrometer
Yang Tao, Xu Chao, Zhou Xinhui, Li Xing′ao, Wei Wei, Huang Wei, Qin Yiqiang, and Zhu Yongyuan
Traditional spectrometers commonly suffer disadvantages of bulky size, low resolution, narrow spectral range, vibration sensibility and high price. In order to overcome the limitations of traditional devices, a novel micro-spectrometer based on optical scattering theory is proposed and demonstrated by using finite diffTraditional spectrometers commonly suffer disadvantages of bulky size, low resolution, narrow spectral range, vibration sensibility and high price. In order to overcome the limitations of traditional devices, a novel micro-spectrometer based on optical scattering theory is proposed and demonstrated by using finite difference time domain (FDTD) simulations. The design contains a series of bubbles with different sizes, which are used to scatter the incident beams. As lights with different wavelengths have different scattering intensity anglar distributions, the pixels after the bubbles can obtain different data which can be substituted into a linear system. The reconstructed spectrum can be obtained by solving the linear system with the Tikhonov regularization method. Simulation results show that the reconstructed spectrum and the incident spectrum are basically coincident. The spectrometer can at least realize a very wide measurement range of 300～1100 nm. Furthermore, the spectrometer can be anticipated to reconstruct the input spectrum with minimum resolutions at picometer order..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue s1, 115004 (2014)
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