Journals >Laser & Optoelectronics Progress
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2016
Volume: 53 Issue 11
40 Article(s)
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Atmospheric Optics and Oceanic Optics
Hartmann Phase Retrieval Method Based on Light Field Information
Zeng Wenhua, Ning Yu, and Du Shaojun
The traditional wavefront retrieval method uses wavefront slope or curvature calculated from the obtained light intensity information to reconstruct wavefront. More light field information is contained in the light intensity information obtained from the structure based on micro lens array. Based on micro lens array stThe traditional wavefront retrieval method uses wavefront slope or curvature calculated from the obtained light intensity information to reconstruct wavefront. More light field information is contained in the light intensity information obtained from the structure based on micro lens array. Based on micro lens array structure, the four-dimensional parametric characterization and the space-space frequency information acquisition and reconstruction of light field are analyzed. The corresponding relationship between the joint distribution of the light field space-space frequency and the Wigner distribution function is established. A Hartmann phase retrieval method based on the light field information is proposed. A numerical calculation model is established and a simulation is carried out. The simulation results show that the proposed phase retrieval method, which uses the light field space-space frequency joint distribution based on light intensity information, can reconstruct phase for low-order aberration effectively and quickly, and the error is small. The proposed method has wide application prospect in aberration compensation of optical imaging system..
Laser & Optoelectronics Progress
- Publication Date: Oct. 27, 2016
- Vol. 53, Issue 11, 110101 (2016)
Diffraction and Gratings
Experimental Research on Strain Transfer Rules of Prestressing Fiber Bragg Grating
You Zewei, Wang Yuan, Sun Yangyang, Huang Xiaodi, and Zhang Zhenglin
In view of measuring strain on the structure surface by the bare fiber Bragg grating（FBG）, and based on the strain transfer model of fiber layer-cement layer-matrix layer, the prestressing effect on the strain transfer rate is studied theoretically and experimentally. The strain on both positive and negative sides of tIn view of measuring strain on the structure surface by the bare fiber Bragg grating（FBG）, and based on the strain transfer model of fiber layer-cement layer-matrix layer, the prestressing effect on the strain transfer rate is studied theoretically and experimentally. The strain on both positive and negative sides of the equal strength beam is measured by means of the prestressing FBG as well as the normal FBG. In order to eliminate the effect of the length and thickness of the cement, the LOCTITE dispenser is used to control the amount of cement. The curve of strain changing with load is obtained. And through comparing with the theoretical strain value of equal strength beam, the curve of strain transfer rate changing with load is received. The results show that the rate of the prestressing FBG is higher than that of the normal FBG for tensile strain mearsuremnet, both of which are above 96%, while the rate of the prestressing FBG is lower than that of the normal FBG for compressive strain mearsuremnet, both of which are above 95%. It corresponds with the theoretical analysis. It proves that the strain transfer rate is improved thanks to the prestressing in the experiment of tensile strain. On the contrary, the rate is reduced because of the prestressing in the experiment of compressive strain..
Laser & Optoelectronics Progress
- Publication Date: Sep. 30, 2016
- Vol. 53, Issue 11, 110501 (2016)
Fiber Optics and Optical Communications
Fixed Length Dual Duration Digital Pulse Interval Modulation for Visible Light Communications
Song Xiaoqing, Jia Shengjie, Zhao Zixu, and Wei Youcai
The digital pulse interval modulation (DPIM) has a higher requirement on the buffer performance compared with the fixed length modulations. So a novel fixed length dual duration digital pulse interval modulation (FDD-DPIM) is presented, and its symbol structure is introduced as well. Through simulations and experimentsThe digital pulse interval modulation (DPIM) has a higher requirement on the buffer performance compared with the fixed length modulations. So a novel fixed length dual duration digital pulse interval modulation (FDD-DPIM) is presented, and its symbol structure is introduced as well. Through simulations and experiments, the bandwidth requirement, average transmission power and error rate performance of the FDD-DPIM are analyzed compared with those of the binary on-off keying (OOK), DPIM, fixed-length digital pulse interval modulation (FDPIM), fixed length dual-amplitude pulse interval modulation (FDAPIM) and dual-amplitude fixed length digital pulse interval modulation (DAFDPIM). The results show that the FDD-DPIM offers higher bandwidth efficiency and average transmission power, and has better error rate performance than the DAFDPIM. Hence, it is believed to be suitable in the visible light communications (VLC) application..
Laser & Optoelectronics Progress
- Publication Date: Sep. 30, 2016
- Vol. 53, Issue 11, 110601 (2016)
Performance Optimization of All-Optical Clock Recovery Based on F-P Cavity by Using Chirped Grating Filter
Yin Yu, and Yu Zhenhong
The principle of using the Fabry-Perot (F-P) cavity to achieve the all-optical clock recovery is explained. Based on the reflection characteristics of the chirped fiber Bragg grating (CFBG), the wavelength selection advantage of using the chirped fiber Bragg grating to filter the signals, before using the F-P cavity toThe principle of using the Fabry-Perot (F-P) cavity to achieve the all-optical clock recovery is explained. Based on the reflection characteristics of the chirped fiber Bragg grating (CFBG), the wavelength selection advantage of using the chirped fiber Bragg grating to filter the signals, before using the F-P cavity to achieve the all-optical clock recovery, is analyzed theoretically. which is that the signals at the wavelength that don't require the clock recovery are filtered out by the CFBG in advance. Due to the side lobes of the CFBG reflection spectrum, the effect of the filter is not quite good, and the quality of the all-optical clock recovery is bad. So the CFBG should be apodized to get a good quality of the all-optical clock recovery..
Laser & Optoelectronics Progress
- Publication Date: Sep. 29, 2016
- Vol. 53, Issue 11, 110602 (2016)
Polarization State Transfer Characteristics Analysis of Coude Type Laser Communication Terminal
Jiang Lun, Wang Chao, An Yan, Liu Zhuang, Li Yingchao, and Zhang Lizhong
A geometric model of Coude type laser communication terminal is established. Its polarization state transfer characteristics are analyzed by using three-dimensional polarization state tracking algorithm. The system polarization state transfer matrix is obtained, and the relationship between azimuth, elevation angle andA geometric model of Coude type laser communication terminal is established. Its polarization state transfer characteristics are analyzed by using three-dimensional polarization state tracking algorithm. The system polarization state transfer matrix is obtained, and the relationship between azimuth, elevation angle and polarization extinction ratio, phase delay angle of Coude type laser communication terminal is established. Numerical simulation is carried out on polarization state of the output signal light. Results show that the output signal polarization state of Coude type laser communication terminal is closely related to the terminal azimuth and elevation angle, which provides a reference for real-time control of polarization state in coherent space laser communication system..
Laser & Optoelectronics Progress
- Publication Date: Oct. 21, 2016
- Vol. 53, Issue 11, 110603 (2016)
Intensity Distribution of the Partially Coherent Vortex Beams Propagating in Atmospheric Turbulence
Ke Xizheng, and Wang Chaozhen
Based on the generalized Huygens-Fresnel principle and the expression of the cross spectral density function, the integral form of intensity distribution of partially coherent Gaussian-Schell vortex beams propagating in the atmospheric turbulence is derived. A complete analytic expression is obtained by some special inBased on the generalized Huygens-Fresnel principle and the expression of the cross spectral density function, the integral form of intensity distribution of partially coherent Gaussian-Schell vortex beams propagating in the atmospheric turbulence is derived. A complete analytic expression is obtained by some special integral processings. The impacts of transmission distance, turbulence intensity and beam parameters on the beam intensity distribution are discussed. The results show that the intensity distribution of the partially coherent vortex beams in the atmospheric turbulence is gradually transformed into the Gaussian distribution by the hollow distribution with increase of the transmission distance. When the topological charge number is zero, the intensity distribution keeps Gaussian distribution with increase of the transmission distance. In terms of invariant turbulence intensity, the smaller the topological charge number is, the shorter the coherent length is, and the longer the waist width is, then the shorter the transmission distance is needed when the intensity distribution is transformed from hollow distribution to Gaussian distribution..
Laser & Optoelectronics Progress
- Publication Date: Sep. 20, 2016
- Vol. 53, Issue 11, 110604 (2016)
Image Processing
Recognition of Three-Dimensional Dynamic Finger Gesture Based on Leap Motion
Yan Limin, Du Bin, Pan Hao, and Guo Qiang
In order to achieve the recognition of dynamic finger gestures based on motion trajectory and promote the development of the cross-cutting areas of human-computer interaction and virtual reality, a recognition method of the key feature points′trajectory is described, which is about finger gesture in three-dimensional (In order to achieve the recognition of dynamic finger gestures based on motion trajectory and promote the development of the cross-cutting areas of human-computer interaction and virtual reality, a recognition method of the key feature points′trajectory is described, which is about finger gesture in three-dimensional (3D) space on basic of Leap Motion. The hand skeleton is extracted by skeleton algorithms with the modeling hand information, which is obtained by the Leap motion controller. Then, the thinning algorithm is used to get straight finger schematic, and extracts feature points and motion trajectory. The basic dynamic 3D finger gestures are identified and evaluated by means of support vector machine (SVM). Experimental results show that the identification of dynamic 3D finger gestures can be achieved in a more complex 3D space or hand block by themselves, and has a high accuracy and robustness..
Laser & Optoelectronics Progress
- Publication Date: Oct. 21, 2016
- Vol. 53, Issue 11, 111001 (2016)
Denoising of Strong Noisy Image via Gradient Reweighted Non-Local Averaging over Learned Dictionaries
Yu Linqian, Qin Yali, and Zhang Xiaoshuai
In order to reconstruct the original image from strong noise image and reduce the error, an improved image denoising algorithm for strong noise images is proposed, which is addressed as gradient reweighted non-local averaging. According to the sparse and redundant representation, the approach is based on K-SVD trained In order to reconstruct the original image from strong noise image and reduce the error, an improved image denoising algorithm for strong noise images is proposed, which is addressed as gradient reweighted non-local averaging. According to the sparse and redundant representation, the approach is based on K-SVD trained dictionaries, which are learned from the corrupted image itself and lead to sparser representations. Nevertheless, the denoising quality is bad for the strong noise image because of the intrinsic structure of dictionaries. The method is proposed to find the inherent structure of images using non-local averaging algorithm with gradient reweighting, which is obtained by total variation, as the tighter constraint over the image. According to the information of edges as the image prior and the redundancy, the optimized solution is used to solve an inverse problem by defining the area of edges higher weights. Compared with the traditional dictionary denoising, the proposed algorithm not only show the superiority of the noise drawn images in peak signal to noise ratio, but also keeps the detail information in structure similarity..
Laser & Optoelectronics Progress
- Publication Date: Oct. 27, 2016
- Vol. 53, Issue 11, 111002 (2016)
Discriminative Low-Rank Projection Dictionary Pair Learning
Qiu Lida, Fu Ping, Lin Nan, and Zhang Ning
Compared with the conventional dictionary learning algorithm, the novel projection dictionary pair learning (DPL) algorithm introduces a projection dictionary in the dictionary learning process and utilizes the projection coding to replace the sparse coding in the dictionary for object samples. The computational cost oCompared with the conventional dictionary learning algorithm, the novel projection dictionary pair learning (DPL) algorithm introduces a projection dictionary in the dictionary learning process and utilizes the projection coding to replace the sparse coding in the dictionary for object samples. The computational cost of the pattern recognition algorithm can be effectively reduced. However, the original DPL algorithm is sensitive to occlusion and noise interference. To solve this problem, a discriminative low-rank projection dictionary pair learning (DLPL) algorithm is proposed. A low-rank constraint is added to the dictionary in the model and the least squares estimation method is used to constrain the classification error of the projection coding for the labeled samples. The unknown dictionary and the projection dictionary with closed solutions can be solved quickly by the alternative optimization method. Experimental results in different databases show that the DLPL algorithm can not only improve the performance of dictionary under occlusion and noise interference and raise the pattern recognition rate, but also effectively reduce the training time and the test time for the model..
Laser & Optoelectronics Progress
- Publication Date: Oct. 24, 2016
- Vol. 53, Issue 11, 111003 (2016)
Face Recognition Based on Local Adaptive Ternary Derivative
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A face recognition algorithm based on fusing Gabor feature and local ternary derivative pattern (LTDP) is proposed. The LTDP method is improved and an adaptive threshold operator is presented in this algorithm. Face images are filtered by the Gabor filter to extract face magnitude features with multi-scale and multi-orA face recognition algorithm based on fusing Gabor feature and local ternary derivative pattern (LTDP) is proposed. The LTDP method is improved and an adaptive threshold operator is presented in this algorithm. Face images are filtered by the Gabor filter to extract face magnitude features with multi-scale and multi-orientation. The local Gabor adaptive ternary derivative pattern (LGATDP2) method is used to extract the local orientation relationship patterns of magnitude feature images. The information entropy weight is calculated by the pattern area histogram statistics, and the face image is described after the weighted series. The similarity match of the feature histograms is carried out with the chi-square distance. The simulations are conducted in the ORL and the Yale databases. The results show that the LGATDP2 method has better universality, and it is more robust under the conditions of illumination variation, expression changing and noise interference..
Laser & Optoelectronics Progress
- Publication Date: Oct. 27, 2016
- Vol. 53, Issue 11, 111004 (2016)
Moving Object Detection Under Infrared Light Mutation
Chen Qiang, Sheng Huixing, Zhang Zhuo, Xie Yingjuan, and Zhang Xuewu
One method combining edge Gaussian mixture model and frame difference is proposed to realize the moving object detection under infrared light mutation, which uses the statistical threshold and image variance change to distinguish the occurrence of light mutation, and introduces a retard factor to upgrade the model. ExpOne method combining edge Gaussian mixture model and frame difference is proposed to realize the moving object detection under infrared light mutation, which uses the statistical threshold and image variance change to distinguish the occurrence of light mutation, and introduces a retard factor to upgrade the model. Experimental results show that, compared with the traditional detection method, the improved method here shows lower rate of false detection, more accurate detection, stronger robustness and stability, and it can effectively solve the false reporting problems induced by light mutation and infrared mode transition in the intelligent security monitoring system..
Laser & Optoelectronics Progress
- Publication Date: Oct. 21, 2016
- Vol. 53, Issue 11, 111005 (2016)
Adaptive Segmentation Algorithm for CT Image Sequence Based on Structure Continuity as Prior Information
Wang Sukai, Pan Jinxiao, and Chen Ping
Soil computer tomographic (CT) images sequence are difficult to extract the target because the gray of the segmented object has no uniform distribution. In order to solve the problems, we come up with an adaptive segmentation algorithm of CT images sequence based on structure continuity as prior information. We choose Soil computer tomographic (CT) images sequence are difficult to extract the target because the gray of the segmented object has no uniform distribution. In order to solve the problems, we come up with an adaptive segmentation algorithm of CT images sequence based on structure continuity as prior information. We choose the initial image and determine the most appropriate threshold. Based on the continuity of the same object structure between the images sequence, the areal change of the object region is used as the prior information to perform recursive segmentation. The adaptive segmentation of CT images are achieved, and 3D visualization is realized by 3D reconstruction on the segmented object area. The results show that the proposed algorithm is applicable to CT images sequence with non-uniform gray distribution in the object regions, it results in small amount of calculation, and can precisely segment objects in thousands of target images..
Laser & Optoelectronics Progress
- Publication Date: Oct. 26, 2016
- Vol. 53, Issue 11, 111006 (2016)
Imaging Systems
Image Texture Detection Based on Multi-Order Ring Structure Quantum Algorithm
Chen Zhiming
In order to improve the effect of image texture detection, the multi-order ring structure quantum algorithm is proposed. The quantum multi-order ring structure is established. Each quantum can communicate with rings of both its own order and other orders, so each quantum can choose two quanta which are connected or locIn order to improve the effect of image texture detection, the multi-order ring structure quantum algorithm is proposed. The quantum multi-order ring structure is established. Each quantum can communicate with rings of both its own order and other orders, so each quantum can choose two quanta which are connected or located at other rings as its neighbors and the number of quanta which choose other rings′quanta as its neighbors is determined randomly. The position is contributed to the capability of the ring and the probability of each order quantum which is optimized is determined self-adaptively. The quantum node information is proposed, including full and same order sharing probability. The image texture local binary detection model is established by amplitude, symbols and gray, the standard deviation is chosen to describe texture complexity for gray in the neighborhood. And, the algorithm process is given. Simulation experiments show that detection texture of the proposed method is clear, the texture is coherent, and the processing time, entropy and average gradient index are better than other algorithms..
Laser & Optoelectronics Progress
- Publication Date: Oct. 21, 2016
- Vol. 53, Issue 11, 111101 (2016)
Hilbert Transform in Full-Field Optical Coherence Tomography
Yang Fan, fanGao Wanrong, and Zhu Yue
High-resolution optical coherence tomographic imaging of biological samples and in vivo biological tissues can be realized by full-field optical coherence tomography (FF-OCT). One of the main problems in FF-OCT is how to get the tomographic images from multiple phase shift interference patterns by the Hilbert transformHigh-resolution optical coherence tomographic imaging of biological samples and in vivo biological tissues can be realized by full-field optical coherence tomography (FF-OCT). One of the main problems in FF-OCT is how to get the tomographic images from multiple phase shift interference patterns by the Hilbert transform. With the Matlab software used, the image quality was simulated with five main Hilbert transforms, 1D Hilbert transform and four kinds of 2D Hilbert transform including (total Hilbert transform, partial Hilbert transform, single orthant Hilbert transform and bi-orthant Hilbert transform). The results show that compared with that obtained by the 1D Hilbert transform, the image contrast by the 2D Hilbert transform increases by about 10%..
Laser & Optoelectronics Progress
- Publication Date: Oct. 28, 2016
- Vol. 53, Issue 11, 111102 (2016)
Influence of Unsteady Wind Loads on Imaging Quality of the 1.2 m Ground Telescope
Lan Bin, Yang Hongbo, Wu Xiaoxia, An Qichang, and Zhao Hongchao
Power spectrum of the unsteady wind loads is describes in detail. The linear relationship between rigid displacement of the optical elements and specular node is built by the least squares method. And the optical sensitivity matrix characterizing the optical image point offset caused by a rigid displacement of the optiPower spectrum of the unsteady wind loads is describes in detail. The linear relationship between rigid displacement of the optical elements and specular node is built by the least squares method. And the optical sensitivity matrix characterizing the optical image point offset caused by a rigid displacement of the optical elements in the optical system is built based on the assumption of small displacement linearization method. Then, these linear relationships are imported into the finite element analysis model of the telescope system and the frequency response analysis of unsteady wind loads is proceeded. The random response curves of image point offset relative to the imaging surface are obtained from input of the power spectral density functions of unsteady wind loads under sixteen cases of different wind speeds and elevation angles. Finally, the random response curve of image point lateral displacement is corrected considering the impact of main axes servo control system and the integration time of imaging elements on image offset. And line spread function (LSF) and modulation transfer function (MTF) attenuation curves caused by the random offset are deduced. The Strehl Ratio of imaging system is calculated in sixteen cases in the short and long exposure time. The results show that the Strehl ratio of the optical system is greater than 0.8, when the telescope is located in fifth level wind under any elevation angle and in sixth and seventh levels wind under near 0° elevation angle. Under the above circumstance, the telescope system can work properly. While the Strehl ratio is less than 0.8, when the telescope is located in eight level wind under any elevation angle. In this case, the image quality of the telescope is seriously affected, so the system cannot work properly..
Laser & Optoelectronics Progress
- Publication Date: Oct. 21, 2016
- Vol. 53, Issue 11, 111103 (2016)
Instrumentation, Measurement and Metrology
Measurement of 2.52 THz Back Scattering in Aluminium Plates with Four Kinds of Roughness
Fan Changkun, Li Qi, Zhou Yi, Zhao Yongpeng, and Chen Deying
Terahertz target scattering characteristic is a very important index to represent the target′s scattering ability of Terahertz. A system to measure target′s scattering characteristic of 2.52 THz is established. The system has a shield compartment, and the beam′s waist width is about 100 mm. With this system, a back scaTerahertz target scattering characteristic is a very important index to represent the target′s scattering ability of Terahertz. A system to measure target′s scattering characteristic of 2.52 THz is established. The system has a shield compartment, and the beam′s waist width is about 100 mm. With this system, a back scattering measurement experiment is conducted on square plates whose roughness Ra are respectively 1.6, 3.2, 6.3, 12.5 μm. The square plates are 40 mm and 45 mm wide. Through analyzing the experimental data and comparing them with the theoretical formula, the feasibility of this system is verified. The experimental results show that the back scattering′s maximum value of the aluminum plates with different roughnesses changes little, when the size of the aluminum plates is the same. While the roughness increases, the back scattering declines from the peak and the gradient trends greater..
Laser & Optoelectronics Progress
- Publication Date: Oct. 20, 2016
- Vol. 53, Issue 11, 111201 (2016)
Eight-Step Phase Shifting Method Being Independent of Gamma Nonlinearity
Yang Liu, Cheng Xiaosheng, Cui Haihua, Dai Ning, and Zhang Chenbo
In order to eliminate the influence of the gamma nonlinearity of the projector on the phase, this paper proposes a method to remove the gamma nonlinearity based on the eight-step phase shifting. The mathematical analysis and derivation of the phase are demonstrated, and the mathematical model is established between phaIn order to eliminate the influence of the gamma nonlinearity of the projector on the phase, this paper proposes a method to remove the gamma nonlinearity based on the eight-step phase shifting. The mathematical analysis and derivation of the phase are demonstrated, and the mathematical model is established between phase and projector gamma. For the gamma nonlinearity error within the four order of the projector, we illustrate that the expression of the phase is independent of the gamma nonlinearity. The experimental results show that the method can effectively reduce the phase error caused by the gamma nonlinearity. The standard deviation of the phase error is reduced to 8.3% of it. Besides, the standard deviation is reduced to 20.5% of it. This method is simple, reliable and universal, and it is not affected by ambient light and system parameters..
Laser & Optoelectronics Progress
- Publication Date: Oct. 21, 2016
- Vol. 53, Issue 11, 111202 (2016)
Error Analysis of Scanning Hartmann Wavefront Testing Technique
Zhang Hao, Yan Feng, Wei Haisong, Chen Xindong, and Cheng Qiang
Based on the surface shape reconstruction algorithm for slope detection in combination with the calibration results of the guideway pointing errors, the influence of the sources of these errors on the actual test results is analyzed and the corresponding numerical simulation and compensation are conducted for the theorBased on the surface shape reconstruction algorithm for slope detection in combination with the calibration results of the guideway pointing errors, the influence of the sources of these errors on the actual test results is analyzed and the corresponding numerical simulation and compensation are conducted for the theoretical analysis. The results show that the wavefront testing technique method based on the scanning Hartmann principle is not sensitive to the high-frequency errors, and the wavefront testing accuracy can be improved by fitting to the low-frequency errors. This finding has an important guiding significance in the engineering application of wavefront testing technique..
Laser & Optoelectronics Progress
- Publication Date: Nov. 22, 2016
- Vol. 53, Issue 11, 111203 (2016)
Method for Improving Measurement Accuracy of Inverse Fringe
Xiao Chao, Chen Feng, and Zhong Min
In order to improve the measurement accuracy of inverse fringe, the measurement method based on the three frequencies temporal phase compensation algorithm is proposed to alleviate the nonlinear error of projector-camera measurement system. Two sets of structured light fringes with specific phase offset are projected oIn order to improve the measurement accuracy of inverse fringe, the measurement method based on the three frequencies temporal phase compensation algorithm is proposed to alleviate the nonlinear error of projector-camera measurement system. Two sets of structured light fringes with specific phase offset are projected onto the testing object, and three frequencies temporal phase unwrapping method is used to obtain the unwrapped phase. The system nonlinear phase errors measured by the two sets of fringes with specific phase offset have the characteristics of the same absolute value and opposite sign. So the effect of the system nonlinear error can be eliminated or alleviated by the simple arithmetic calculation, and the measurement accuracy can be improved. The analog simulation and real object contrast experiments are designed to verify the proposed method. Phase standard deviations in the experiments are 6.6122×10-4 rad and 0.0087 rad, respectively. The experiments results show that the proposed method has a great improvement in inverse fringe measurement accuracy, and the validity of proposed method is verified..
Laser & Optoelectronics Progress
- Publication Date: Oct. 25, 2016
- Vol. 53, Issue 11, 111204 (2016)
Lasers and Laser Optics
Theoretical Research and Experimental Analysis on the Depth Measurement of Subsurface Damage
Xu Yixuan, Jiang Zhengdong, Wang Hualin, and He Yong
The subsurface damage of optical components is the scratches and cracks which are produced in workpiece process. The subsurface damage will change the light field under the laser irradiation. As the laser irradiation time increases, the cracks become larger and generate scattering, which finally effect the encircled enThe subsurface damage of optical components is the scratches and cracks which are produced in workpiece process. The subsurface damage will change the light field under the laser irradiation. As the laser irradiation time increases, the cracks become larger and generate scattering, which finally effect the encircled energy of laser beam. This paper proposes a new method to estimate damage depth based on the principle of subsurface damage measured by total internal reflection method. Incident and exit light waves are superimposed to form the standing wave under the surface of sample, and the polarization state and the incident angle of incident light affect the distribution of light intensity in the sample. By analyzing the relation between light intensity and incident angle of subsurface damage point, the depth of subsurface damage can be estimated through the change quantity of the incident angle..
Laser & Optoelectronics Progress
- Publication Date: Oct. 20, 2016
- Vol. 53, Issue 11, 111401 (2016)
Experimental Study on Laser Processing Arrayed Conical Micro-Holes of CVD Diamond Films
Wang Peng, Zhang Fenglin, Liu Wenguang, and Ouyang Chengda
The arrayed conical micro-holes are drilled by pulse fiber laser on chemical vapor deposition diamond films. The influence of such parameters as laser scanning speed, scanning times and pulse width on the shape and size of micro-holes are investigated. The results show that the laser scanning speed has less obvious infThe arrayed conical micro-holes are drilled by pulse fiber laser on chemical vapor deposition diamond films. The influence of such parameters as laser scanning speed, scanning times and pulse width on the shape and size of micro-holes are investigated. The results show that the laser scanning speed has less obvious influence on the micro-hole dimension, in contrast, laser scanning times have significant influence on the micro-hole exit diameter. With the increment of laser pulse width, the micro-hole depth and exit diameter both increase, but the micro-hole conical degree decreases..
Laser & Optoelectronics Progress
- Publication Date: Oct. 21, 2016
- Vol. 53, Issue 11, 111402 (2016)
Analysis of Processing Parameters for Laser Cutting High-Temperature Alloy Steel by Orthogonal Method
Chen Yuxiang, and Gao Liang
The processing parameters for cutting the high-temperature alloy steel (the mark is GH3128) by Nd∶YAG laser are studied. Eighteen experiments are conducted by the orthogonal method. The factors which influence the quality of laser cutting, including oxygen pressure, defocusing distance, cutting speed, input current, puThe processing parameters for cutting the high-temperature alloy steel (the mark is GH3128) by Nd∶YAG laser are studied. Eighteen experiments are conducted by the orthogonal method. The factors which influence the quality of laser cutting, including oxygen pressure, defocusing distance, cutting speed, input current, pulse width, frequency and error, are studied. The slag thickness and the kerf width are observed after laser cutting, and the comprehensive assessment is worked out. The influence of processing parameters on the cutting quality is studied by the intuitive analysis method. The optimal parameters are obtained, and verification experiments are conducted based on these optimal parameters. Interaction effect and block-group difference among these factors are studied by the variance analysis method, and the influence of interaction effect and block-group difference on the cutting quality is studied. The results show that the orthogonal method can optimize the slag thickness and the comprehensive assessment, but cannot optimize the kerf width..
Laser & Optoelectronics Progress
- Publication Date: Oct. 27, 2016
- Vol. 53, Issue 11, 111403 (2016)
Microstructure and Mechanical Property of S-04 Steel by Selective Laser Melting
Jing Guanyi, Wei Kaiwen, Wang Zemin, Yin Jie, and Zeng Xiaoyan
Selective laser melting (SLM) technology is used to fabricate S-04 specimens, and their microstructures and mechanical properties before and after heat-treatment are researched. The results show that the density of S-04 molded sample can be up to 99.791% and the specimens before and after heat-treatment are both composSelective laser melting (SLM) technology is used to fabricate S-04 specimens, and their microstructures and mechanical properties before and after heat-treatment are researched. The results show that the density of S-04 molded sample can be up to 99.791% and the specimens before and after heat-treatment are both composed of α′ martensite and a little residual γ austenite. The untreated specimen possess a multi-layer stacked character peculiar to the SLM technique, whereas after heat-treatment, this character disappears and the main specimen phase is bunchy martensite. The mechanical property at room temperature of heat-treated specimens is better than that of non-heat-treated ones..
Laser & Optoelectronics Progress
- Publication Date: Oct. 21, 2016
- Vol. 53, Issue 11, 111404 (2016)
Machine Vision
High Speed Camera Calibration for Velocity Measurement in Range Static Explosion Experiment
Liu Zeqing, Zhang Yurong, Zhao Jianxin, and Du Bojun
A calibration equipment for the range static explosion experiment site is designed, a calibration method for high speed camera based on genetic simulated annealing is studied, and an experiment which calibrates the internal and external parameters of the binocular high speed camera by the designed calibration equipmentA calibration equipment for the range static explosion experiment site is designed, a calibration method for high speed camera based on genetic simulated annealing is studied, and an experiment which calibrates the internal and external parameters of the binocular high speed camera by the designed calibration equipment is carried out. According to the circular manually-labelled position parameters collected in experiment, the parameters of the binocular high-speed camera are calibrated by the genetic simulated annealing based method and the Tsai two step calibration method respectively. The parameters calibrated by the two methods are used to restore the spatial coordinates of known points in sight. By comparing the restored results with the measurement coordinates, it is found that the maximum deviation of the spatial coordinates restored by the proposed method is 0.0082 m, which is better than the maximum deviation of the Tsai two-step calibration method (0.0201 m). With the proposed method, the calibration accuracy of the high speed camera is improved, and the method is of great significance for the improvement of the fragment velocity measurement accuracy..
Laser & Optoelectronics Progress
- Publication Date: Oct. 25, 2016
- Vol. 53, Issue 11, 111501 (2016)
Medical Optics and Biotechnology
Influence of He-Ne Laser on "Root-Bending" in Wheat Induced by Enhanced UV-B irradiation
Wang Yan, Dong Qiannan, Meng Jing, and Zhang Meiping
In order to study the influence of He-Ne laser on "root-bending" in wheat caused by enhanced UV-B irradiation, the wheat seedlings were exposed to He-Ne laser with 5 mW·mm-2 power density after enhanced UV-B irradiation (10.08 kJ·m-2·d-1). The content of actin, the content and type variety of fIn order to study the influence of He-Ne laser on "root-bending" in wheat caused by enhanced UV-B irradiation, the wheat seedlings were exposed to He-Ne laser with 5 mW·mm-2 power density after enhanced UV-B irradiation (10.08 kJ·m-2·d-1). The content of actin, the content and type variety of flavonoids in wheat roots were studied. The results show that compared with those of the contrast group, the main radical length becomes shorter, the content of actin and flavonoids in the UV-B irradiation enhanced group is reduced, while the He-Ne laser treated group has no notable difference. The results of the group under simultaneous irradiation of UV-B and He-Ne laser are lower than those of the contrast group but higher than those of the UV-B irradiated group, and the "root bending" phenomenon is weakened. The migration rates of flavonoids are different in diverse groups. There appear various flavonoids varieties under UV-B irradiation. The variation in content of actin and flavonoids is one of the reason for "root bending". The damage on wheat seedlings induced by UV-B irradiation can be partially repaired by He-Ne laser irradiation..
Laser & Optoelectronics Progress
- Publication Date: Oct. 28, 2016
- Vol. 53, Issue 11, 111701 (2016)
Microscopy
Optimization of Lateral Resolution in Confocal Microscopic Imaging with CCD as a Detector
Shi Yaqin, Zhang Yunhai, and Xiao Yun
In recent years, confocal microscopic imaging with charge coupled device (CCD) as a detector is a new method of confocal imaging. In this scheme, the lateral resolution of system is not only affected by the numerical aperture of the objective, but also the pixel of CCD, which is in the point spread function area of imaIn recent years, confocal microscopic imaging with charge coupled device (CCD) as a detector is a new method of confocal imaging. In this scheme, the lateral resolution of system is not only affected by the numerical aperture of the objective, but also the pixel of CCD, which is in the point spread function area of imaging and detection part. Using CCD instead of the pinhole and point detector of conventional confocal imaging, the synthetic equivalent pinhole of CCD pixel is chosen by different sizes of the point spread function area of a certain combination. The optimized synthetic pinhole is got by comparing the lateral resolution of system with different sizes of synthetic pinhole. By weighted subtracting of the image from different synthetic pinholes, subtractive imaging is realized and the lateral resolution can be enhanced. Experimental results show that when the synthetic pinhole is 0.8 times (8 pixel×8 pixel) of Airy spot diameter, the scanning image has higher lateral resolution and signal to noise ratio. When the image with the larger pinhole (10 pixel×10 pixel) is weightedly subtracted from the image with the optimized pinhole (8 pixel×8 pixel), the lateral resolution of subtractive image relative to optimized pinhole image with weight coefficient of 0.6 is improved by 21.7%. Using CCD as a detector can greatly reduce the complexity of the conventional confocal imaging system. By selecting the optimized synthetic pinhole and processing subtractive imaging, we can improve the lateral resolution of imaging..
Laser & Optoelectronics Progress
- Publication Date: Oct. 20, 2016
- Vol. 53, Issue 11, 111801 (2016)
Optical Design and Fabrication
Research on Precise Alignment Technique for Transport System Installation of Shenguang-Ⅲ Laser Driver
Cao Tingfen, Xiong Zhao, Li Keyu, Li Qi, Liu Changchun, Ye Haixian, Chen Haiping, Luo Huan, Jiang Xinying, Zhou Hai, Yuan Xiaodong, and Wei Xiaofeng
In order to realize the precise alignment of normal orientation of mirrors in the long-distance optical transmission path of high-power laser device, installation error sources based on mirror normal orientation are analyzed. As for the structural and installation features of high-power laser device, a precise alignmenIn order to realize the precise alignment of normal orientation of mirrors in the long-distance optical transmission path of high-power laser device, installation error sources based on mirror normal orientation are analyzed. As for the structural and installation features of high-power laser device, a precise alignment scheme which combines pre-collimation, module-pose off-line coping, and flexible joining is selected. The off-line collimation and reset precision are verified, and the experimental data confirms the feasibility of the above scheme. This technique has achieved favorable effectiveness in the assembly and debugging of transport system in Shenguang-Ⅲ laser driver..
Laser & Optoelectronics Progress
- Publication Date: Oct. 21, 2016
- Vol. 53, Issue 11, 112201 (2016)
Optical System Design of Plume Ultraviolet Radiation Monitor Unit
[in Chinese], [in Chinese], and [in Chinese]
To monitor the plume ultraviolet (UV) radiation during the satellite attitude adjustment, we need to develop an optical system with UV spectral range, large field of view and small size. Based on the principle of UV imaging, the initial structure with large field of view and aperture is realized by using two optical maTo monitor the plume ultraviolet (UV) radiation during the satellite attitude adjustment, we need to develop an optical system with UV spectral range, large field of view and small size. Based on the principle of UV imaging, the initial structure with large field of view and aperture is realized by using two optical materials of fused silica and calcium fluorite. The scheme of all spherical surface optical system with focal length of 25 mm, field of view of 40° and aperture F number of 2 is introduced. The optical system is optimized by using optical design software Zemax and Code V, and the UV imaging lens that satisfies the requirement is obtained. The diameters of defocus spot for all fields of view are less than 11 μm, and transfer functions of all fields of view are better than 0.6 at the detector′s characteristic frequency of 40 lp/mm, which satisfy the requirements of fabrication and state. Compared with the other UV objective lenses, the proposed system achieves large field of view and aperture, and the surfaces of the lenses are all sphere. Which can effectively reduce the cost and shorten the process cycle..
Laser & Optoelectronics Progress
- Publication Date: Oct. 25, 2016
- Vol. 53, Issue 11, 112202 (2016)
Application of Low-Light Night-Vision Objective Lens with Double-Layer Diffractive Optical Element
Zhao Xiang, Zhang Peng, and Luo Jinping
The design of low-light lens with diffractive optical element (DOE) can reduce the volume and weight of lens. DOE can correct aberrations well in virtue of its negative diffusion performance that is different from traditional lenses. The diffraction efficiency of a single-layer DOE can reach 100% only at a specific wavThe design of low-light lens with diffractive optical element (DOE) can reduce the volume and weight of lens. DOE can correct aberrations well in virtue of its negative diffusion performance that is different from traditional lenses. The diffraction efficiency of a single-layer DOE can reach 100% only at a specific wavelength, and obviously decreases with the change of wavelength. The double-layer DOE has higher diffraction efficiency at any wavelength in the entire working band. A low-light night-vision objective lens system with double-layer DOEs is designed based on the excellent performance of double-layer DOEs. The diffraction efficiency of the double-layer DOE is higher than 98% in the working band from 0.65 μm to 0.9 μm. The length of the system is 60 mm, the field of view is 40°, the F number is 1.2, and the focal length is 25 mm. The simulation result shows that the system has fine imaging quality, and the modulation transfer function value is greater than 0.5 at the spatial frequency of 40 lp/mm..
Laser & Optoelectronics Progress
- Publication Date: Oct. 20, 2016
- Vol. 53, Issue 11, 112203 (2016)
Optical Devices
Analysis of Laser Retro-Reflector on GRACE Gravity Satellite
Luo Qingshan, Guo Tangyong, Yao Yunsheng, Zou Tong, Li Xin, Zhu Wei, and Li Shipeng
Taking the laser retro-reflector on GRACE gravity satellite as an example, the main technical parameters, such as the laser incident angle of laser retro-reflector on satellite, velocity aberration compensation, and the relatively effective reflection area, are analyzed theoretically, and the testability and ranging erTaking the laser retro-reflector on GRACE gravity satellite as an example, the main technical parameters, such as the laser incident angle of laser retro-reflector on satellite, velocity aberration compensation, and the relatively effective reflection area, are analyzed theoretically, and the testability and ranging error analyses for a laser retro-reflector on satellite are conducted as well. By using the TROS1000 mobile satellite laser ranging (SLR) system, a ranging experiment on the laser retro-reflector on GRACE satellite with a precision of 0.9 cm is conducted and the experimental result is basically consistent with the theoretical analysis result..
Laser & Optoelectronics Progress
- Publication Date: Oct. 20, 2016
- Vol. 53, Issue 11, 112301 (2016)
Performance of Oxygen Passivation Silicon-Based ZnO/Nanoporous Si Pillar Array Heterojunction Near White Light LED
Liu Chunling, Dou Yu, Chen Chen, Wang Chunwu, and Jiang Wenlong
The nano heterojunction light emitting diode (LED) with structure of indium oxide (ITO)/ZnO/nanoporous Si pillar array(NSPA)/Si/Al is designed and fabricated, and the near white light electroluminescence (EL) is realized. Firstly, the NSPA layer is prepared on the surface of P-Si by using the vapor etching technique. TThe nano heterojunction light emitting diode (LED) with structure of indium oxide (ITO)/ZnO/nanoporous Si pillar array(NSPA)/Si/Al is designed and fabricated, and the near white light electroluminescence (EL) is realized. Firstly, the NSPA layer is prepared on the surface of P-Si by using the vapor etching technique. Then, the surface of the NSPA is passivated by oxygen plasma and the luminescent properties of NSPA silicon substrate are improved by optimizing the passivation parameters. Finally, N type ZnO thin film is grown on the NSPA surface, and ZnO/NSPA nano heterojunction light emitting diodes are developed. The experimental results show that the oxygen plasma passivation treatment can effectively improve the light intensity of the device and realize an emission of near white light..
Laser & Optoelectronics Progress
- Publication Date: Oct. 25, 2016
- Vol. 53, Issue 11, 112302 (2016)
OPTOELECTRONICS
Laser Power Measurement Method Based on High Performance Black Silicon MEMS Thermopile Power Meter
Li Jingnan, Bao Aida, and Qin Li
Traditional laser power meter has the defects of large volume, slow response, and are difficult to guarantee the detection accuracy, so a laser power measurement method based on high performance black silicon MEMS thermopile power meter is put forward. The test method uses the laser thermal effects, and CO2 laser is usTraditional laser power meter has the defects of large volume, slow response, and are difficult to guarantee the detection accuracy, so a laser power measurement method based on high performance black silicon MEMS thermopile power meter is put forward. The test method uses the laser thermal effects, and CO2 laser is used as the measured laser source, and the black silicon MEMS thermopile detector is the laser detection sensor. Based on the principle of energy conversion, the absorbed laser radiation by a thermopile is converted into its thermodynamic energy, and the thermodynamic energy is input to the CMOS interface circuit in the manifestation of the potential. Potential input data are collected and processed by TopView2000 application software, and the data of the laser power are obtained. Under the room temperature condition, the MEMS laser power detection system repeat test is carried out under the CO2 laser irradiation with different duty cycles and different light time. Under the conditions of 30% laser output duty ratio and the 150 ms total light time, the experimental results show that the response time of the system is 14.92 ms, the laser power value is calculated as 23.01 W, and the measurement uncertainty of the system is 0.55%, which meets the needs of high precision, low cost, low power consumption and portability of laser power in practical application..
Laser & Optoelectronics Progress
- Publication Date: Oct. 21, 2016
- Vol. 53, Issue 11, 112501 (2016)
Remote Sensing and Sensors
Remote Sensing Image Segmentation Based on Fractal Net Evolution Approach and Improved Fuzzy C-Means
Wang Min, Song Zhengfu, and Wang Zhihui
Aiming at the optimal scale in multi-scale segmentation technology selection problem, a method is put forward based on fractal net evolution approach and improved fuzzy c-means of remote sensing image segmentation. In this method, the original image is segmented by small scale using fractal net evolution approach. The Aiming at the optimal scale in multi-scale segmentation technology selection problem, a method is put forward based on fractal net evolution approach and improved fuzzy c-means of remote sensing image segmentation. In this method, the original image is segmented by small scale using fractal net evolution approach. The global search capability of the particle swarm method is used to determine the optimal initial clustering center from the pre-segmented small scale objects. When small scale objects are merged, the objective function of the object spatial information and the correlation information between objects is established. Ultimately, the segmentation results which can adapt to different scale features are obtained, and the excessive dependence on the scale parameters is reduced. Experimental results show that this method can obtain high quality segmentation results of remote sensing images..
Laser & Optoelectronics Progress
- Publication Date: Oct. 21, 2016
- Vol. 53, Issue 11, 112801 (2016)
Reviews
Ultrafast Laser Annealing of Semiconductors
Bai Feng, and Zhao Quanzhong
The technique that intense laser pulses is used to anneal the lattice has been established a thermal process since it was discovered in 2074. The thermal model works well for any material that is excited with picosecond or longer-duration laser pulses. For femtosecond and shorter-duration laser pulses, however, the latThe technique that intense laser pulses is used to anneal the lattice has been established a thermal process since it was discovered in 2074. The thermal model works well for any material that is excited with picosecond or longer-duration laser pulses. For femtosecond and shorter-duration laser pulses, however, the lattice structural changes can be driven directly by electronic excitation. This means that annealing can be completed under melting point. The ultrashort laser pulse annealing is a non-thermal process and it is a new way of annealing. This review focuses on the nature of thermal and non-thermal models. The history, current situation, and the trend of ultrashort laser pulse annealing are also summarized..
Laser & Optoelectronics Progress
- Publication Date: Oct. 28, 2016
- Vol. 53, Issue 11, 110001 (2016)
Absorption Modulation Method of Terahertz Metamaterial
Zhang Jianna, Zhang Bo, and Shen Jingling
The metamaterial absorber consists of metallic resonator, dielectric layer and metallic ground plane. Using impedance matching theory or multi-reflection interference theory can explain why the metamaterial structure can absorb the incident waves perfectly at one specific resonance absorption peak, qualitatively or quaThe metamaterial absorber consists of metallic resonator, dielectric layer and metallic ground plane. Using impedance matching theory or multi-reflection interference theory can explain why the metamaterial structure can absorb the incident waves perfectly at one specific resonance absorption peak, qualitatively or quantitatively. However, metamaterial structure can only absorb incident waves perfectly at a specific frequency once the structure parameters are fixed. Therefore, methods to obtain tunable metamaterial absorbers have attracted widespread attention. In recent years, the author′s team has focused on how to achieve the dynamic modulation of metamaterial absorber. Based on this, the ways to modulate the absorption of terahertz metamaterial absorber are reviewed, including varying the dielectric layer thickness, modulating the conductivity of ground plane, and adding photoconductive materials to the gaps of the metallic resonator. A brief outlook is presented by focusing on the absorption modulation of terahertz metamaterial..
Laser & Optoelectronics Progress
- Publication Date: Oct. 20, 2016
- Vol. 53, Issue 11, 110002 (2016)
Research Progress of Manipulating Tribological Property of Materials by Ultrashort-Pulse-Induced Surface Micro-Nano Texture
Wang Zhuo, and Zhao Quanzhong
Ultrashort pulsed laser surface texturing possesses the advantages of simple process, fast processing speed, fine and precision, and so on, which is one of the most promising preparation ways for surface texturing. By the ultrashort pulsed laser technology, various kinds of micro-nano structures on material surfaces caUltrashort pulsed laser surface texturing possesses the advantages of simple process, fast processing speed, fine and precision, and so on, which is one of the most promising preparation ways for surface texturing. By the ultrashort pulsed laser technology, various kinds of micro-nano structures on material surfaces can be induced in order to control the tribological properties of materials. The recent progress of manipulating the tribological property of materials by ultrashort-pulse-induced surface texturing is reviewed, and the potential applications of such technology in various fields are also discussed..
Laser & Optoelectronics Progress
- Publication Date: Oct. 25, 2016
- Vol. 53, Issue 11, 110003 (2016)
Development Trend of Tactical Laser Weapons
Cheng Yong, Guo Yanlong, Tang Huang, Zhu Mengzhen, Mi Chaowei, Tan Chaoyong, Li Wei, Lu Yimin, and Huang Guojun
Recent development of aircraft-based, satellite-based, ship-based and vehicle-based tactical laser weapons shows the practical prospects of tactical laser weapons, although existing series of experiments could only beat targets like rockets, unmanned aerial vehicle and so on at short range. Key technologies of tacticalRecent development of aircraft-based, satellite-based, ship-based and vehicle-based tactical laser weapons shows the practical prospects of tactical laser weapons, although existing series of experiments could only beat targets like rockets, unmanned aerial vehicle and so on at short range. Key technologies of tactical laser weapons include high energy pulse or composite (cw and pulse together) solid laser technology, beam combination technology, etc. The development trend of laser weapons has made a transition from super high power strategic overawe to low power tactical application. The ship-based laser weapons are expected to be the first actual combat equipment; the development of space-based laser weapons is one of the important directions of laser weapon research because of their important strategic value, the ideal working condition in space without air and no need of high laser power. In the near future, laser weapons will be the subversive weapons that can change existing war forms..
Laser & Optoelectronics Progress
- Publication Date: Oct. 09, 2016
- Vol. 53, Issue 11, 110004 (2016)
Spectroscopy
Determination of Heavy Metal Chromium in Rice Husk by LIBS Coupled with SiPLS
Wang Caihong, Huang Lin, Liu Muhua, Chen Tianbing, Yang Hui, and Yao Mingyin
To explore the feasibility of rapid and green determination of chromium (Cr) in rice husk from polluted paddy fields by laser-induced breakdown spectroscopy (LIBS), synergy interval partial least squares (SiPLS) combined with LIBS was employed for a quantitative analysis of Cr in 24 rice husk samples from different polTo explore the feasibility of rapid and green determination of chromium (Cr) in rice husk from polluted paddy fields by laser-induced breakdown spectroscopy (LIBS), synergy interval partial least squares (SiPLS) combined with LIBS was employed for a quantitative analysis of Cr in 24 rice husk samples from different polluted paddy fields around a certain lake in Jiangxi Province. The real concentration in samples was determined by atomic absorption spectroscopy (AAS), and it ranged from 32.51 μg/g to 510.33 μg/g. The LIBS profiles of rice husk samples in the range of 422-446 nm were collected and three characteristic spectral lines, Cr I 425.43 nm, Cr I 427.48 nm, and Cr I 428.97 nm, were clear. The spectra from 422 nm to 446 nm were processed by the nine-point smoothing method, and then an optimal model was established with the SiPLS method. The results show that the root mean square error of cross validation and the root mean square error of prediction set were 26.1 μg/g and 22.6 μg/g, respectively, and the correlation coefficients for the training set and the prediction set were 0.9714 and 0.9840, respectively. The relative error was calculated and the T-test was carried out. The results indicate that the average relative error was 6.20% between predicted values from the SiPLS algorithm and real values from AAS, and there is no significant difference. The proposed model has high prediction accuracy, and provides reference for the rapid green determination of heavy metals in natural agricultural products..
Laser & Optoelectronics Progress
- Publication Date: Oct. 26, 2016
- Vol. 53, Issue 11, 113001 (2016)
Quality Examination of Methanol Diesel Oil by Raman Spectroscopy
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Methanol content and viscosity of methanol diesel oil were quantitatively detected by Raman spectroscopy. As the detected objects, 93 methanol diesel samples were divided into the calibration set (72 samples) and the prediction set (21 samples). The spectral full cross validation partial least squares (PLS) model were Methanol content and viscosity of methanol diesel oil were quantitatively detected by Raman spectroscopy. As the detected objects, 93 methanol diesel samples were divided into the calibration set (72 samples) and the prediction set (21 samples). The spectral full cross validation partial least squares (PLS) model were analyzed and compared with different pretreatment methods; The spectral data obtained by the optimal pretreatment method is used as inputs, combining with the successive projections algorithm（SPA）to establish different regressive correction models, and these models were comparatively analyzed. The results show that the multiplicative scatter correction partial least squares (MSC-PLS) model for prediction of methanol content is optimal. In this model, the calibration correlation coefficient RC is 0.9761, the interactive validation correlation coefficient RCV is 0.9551, the root mean square error of calibration set (RMSEC) is 1.5089, and the root mean square error of cross-validation（RMSECV）is 2.0630. For viscosity determination, MSC-PLS model also has the best prediction performance, whose RC is 0.9794, RCV is 0.9580, RMSEC is 0.0907 mPa·s, and RMSECV is 0.1292 mPa·s..
Laser & Optoelectronics Progress
- Publication Date: Oct. 28, 2016
- Vol. 53, Issue 11, 113002 (2016)
Measurement of Trace Copper in Water by Laser-Induced Breakdown Spectroscopy Using Montmorillonite Substrate
Wu Qingfeng, Hao Dongyuan, Shi Jun, Huang Da, Chen Shanjun, Xiong Yan, and Wang Yang′en
In order to achieve rapid and highly sensitive detection of copper in natural water by laser-induced breakdown spectroscopy (LIBS), the water samples were analyzed by LIBS after copper therein was enriched by montmorillonite substrate. According to the emission spectral characteristics of copper enriched on the solid sIn order to achieve rapid and highly sensitive detection of copper in natural water by laser-induced breakdown spectroscopy (LIBS), the water samples were analyzed by LIBS after copper therein was enriched by montmorillonite substrate. According to the emission spectral characteristics of copper enriched on the solid substrate, the characteristic spectral line of copper at 324.7 nm was chosen as the analytical line of copper. Measurements of the intensity and signal to noise ratio of the analytical line in different parameter occasions show that the optimal laser spot size is 100 μm, the optimal pulse laser energy was 45.9 mJ, and the optimal delay time is 3 μs. Under the optimized experimental conditions, the calibration curve of copper was established. The linear correlation coefficient with 0.996 indicates a good linear relationship between the copper concentration in water and the intensity of the analytical line. The detection limit for copper in water reached 0.03 mg/L. Furthermore, the method was used to determine the copper concentration in water samples collected from different sites. The measurement results are consistent with those measured by the inductively coupled plasma-atomic emission spectrometry, indicating that the method can be applied in the measurement of trace copper in natural water..
Laser & Optoelectronics Progress
- Publication Date: Oct. 28, 2016
- Vol. 53, Issue 11, 113003 (2016)
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