Journals >Laser & Optoelectronics Progress
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2014
Volume: 51 Issue 10
32 Article(s)
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Atmospheric Optics and Oceanic Optics
Effect of Typhoon NALGAE on the Distribution of Phytoplankton
Yang Chaoyu
Optical property of phytoplankton is studied based on the physical and biological properties in China Sea. A new algorithm, combined with global system for mobile communication model and fluorescence model, is applied to retrieve the phytoplankton information. In the algorithm, twice optimization procedure is performedOptical property of phytoplankton is studied based on the physical and biological properties in China Sea. A new algorithm, combined with global system for mobile communication model and fluorescence model, is applied to retrieve the phytoplankton information. In the algorithm, twice optimization procedure is performed to get the best results. This combined algorithm is applied to simulate the underwater light field by using Hydrolight. The comparison of the sinulation results and synthetic data shows that the algorithm is effective to retrieve the optical information of phytoplankton. In addition, by using optical satellite data (MERIS) and the dynamic parameters, the impact of NALGAE on phytoplankton distribution is analyzed. The result shows Ekman pumping is one of reasons for the ocean color anomalies..
Laser & Optoelectronics Progress
- Publication Date: Sep. 09, 2014
- Vol. 51, Issue 10, 100101 (2014)
Detectors
Data Acquisition Circuitry Design for Extreme Ultraviolet Photon-Counting Imaging Detector
Zhang Kai, and Ni Qiliang
To collect data at a high speed and display the picture of the photon position on the computer by the extreme ultraviolet (EUV) photon-counting imaging detector, a data acquisition circuit is designed. The principle of the photon-counting imaging detector based on position sensitive strip wedge anode is analyzed. The hTo collect data at a high speed and display the picture of the photon position on the computer by the extreme ultraviolet (EUV) photon-counting imaging detector, a data acquisition circuit is designed. The principle of the photon-counting imaging detector based on position sensitive strip wedge anode is analyzed. The high-performance analog/digital (A/D) conversion chips are chosen to collect and convert the analog signals from the circuit with the peak holding block removed to digital signals under the control of the field programmable gate array (FPGA) chip. FPGA will process the received digital signals according to certain rules and send them to the computer by USB data transfer system. The developed software computes the data, draws the photon position picture according to the computed results and displays it. The experimental results show that the circuit system performs well with the highest sampling and converting speed of 2 MHz and the capability of 3-way simultaneous sampling. The image analysis shows that the picture has good linearity and 5 lp/mm spatial resolution. The circuit can collect the data and graph images fast and accurately, which completely meets the requirements of an EUV detector..
Laser & Optoelectronics Progress
- Publication Date: Sep. 09, 2014
- Vol. 51, Issue 10, 100401 (2014)
Diffraction and Gratings
Low Numerical Aperture Focusing System Optical Trapping Multiple Rayleigh Particles
Zhao Yan, and Zhang Yaoju
Two beams of light with different polarizations are incident on a focusing system with two lenses. Based on Richard-Wolf vectorial diffraction theory, the diffraction field distribution is calculated. Properties of optical trapping using the focusing system are analyzed when numerical aperture (NA) of lenses is low. A Two beams of light with different polarizations are incident on a focusing system with two lenses. Based on Richard-Wolf vectorial diffraction theory, the diffraction field distribution is calculated. Properties of optical trapping using the focusing system are analyzed when numerical aperture (NA) of lenses is low. A gold particle′s refractive index is higher than that of the medium (nm), and an air bubble′s is lower. When NA=0.58 nm, subwavelength bright and dark spot array is generated on the optical axis. These spots can be used to trap multiple gold particles and air bubbles. When NA=0.35 nm, wavelength cylindrical rings are formed around the optical axis, which can be used to two-dimensionally trap multiple air bubbles..
Laser & Optoelectronics Progress
- Publication Date: Aug. 22, 2014
- Vol. 51, Issue 10, 100501 (2014)
Fiber Optics and Optical Communications
Temperature Dependence of Absorption and Emission Cross Sections in Erbium-Doped Fibers
Xu Hongjie, and Du Saihui
In order to obtain absorption and emission cross sections spectrum, the relationship between loss coefficient, absorption, emission cross sections and temperature are theoretically analyzed. Spectra for loss, absorption and emission are studied experimentally at various temperatures. The loss spectrum is measured by thIn order to obtain absorption and emission cross sections spectrum, the relationship between loss coefficient, absorption, emission cross sections and temperature are theoretically analyzed. Spectra for loss, absorption and emission are studied experimentally at various temperatures. The loss spectrum is measured by the cut- back method. The absorption spectrum is attained by the loss spectrum. Then based on absorption spectrum, the emission spectrum via the McCumber relation is received. Experiment shows that the loss coefficient are decreased when the wavelength is less than 1536 nm and increased when the wavelength is larger than 1536 nm as temperature increased..
Laser & Optoelectronics Progress
- Publication Date: Aug. 06, 2014
- Vol. 51, Issue 10, 100601 (2014)
Fourier Optics and Signal Processing
Optical Image Encryption with Ciphertext of a Single Diffraction Intensity Pattern
Bai Yinbuhe, Li Genquan, Lü Linxia, and Qin Yi
A novel method for image encryption by employing the diffraction imaging technique is proposed. This method is in principle suitable for most of the diffractive-imaging-based optical encryption schemes, and the classical double random phase encoding in the Fresnel domain is taken for an example for illustrating it. TheA novel method for image encryption by employing the diffraction imaging technique is proposed. This method is in principle suitable for most of the diffractive-imaging-based optical encryption schemes, and the classical double random phase encoding in the Fresnel domain is taken for an example for illustrating it. The encryption process is rather simple because only a single diffraction intensity pattern is needed to be recorded. The security keys include, in addition to the two phase only masks in the input and the Fresnel plane, the sparse data of the plaintext that can be obtained with a simple digital means. The sparse data serve as partial input plane support constraint in a phase retrieval algorithm, which is employed for completely retrieving the plaintext. Simulation results are presented to verify the validity of the proposed approach..
Laser & Optoelectronics Progress
- Publication Date: Sep. 09, 2014
- Vol. 51, Issue 10, 100701 (2014)
Image Processing
An Efficient Stereo Matching Method Based on Bayesian Theory
Li Jiao, Qian Weixian, Chen Qian, Gu Guohua, and Ren Jianle
Ensuring both of the algorithm accuracy and speed is a key technical problem of stereo matching algorithms. A fast dense stereo matching algorithm based on Bayesian is presented. Bayesian probability theory is applied to the stereo matching problem, the support points are extracted with the MSERDoG operator with the piEnsuring both of the algorithm accuracy and speed is a key technical problem of stereo matching algorithms. A fast dense stereo matching algorithm based on Bayesian is presented. Bayesian probability theory is applied to the stereo matching problem, the support points are extracted with the MSERDoG operator with the pixel gray value as the matching cost and the fixed window as the cost aggregation matched, the matched support points are triangulated, the disparity and gradient of the support points, the formation of the linear coefficient triangulation and segmentation are selected as priori probability conditions, thus ensuring efficient disparity search space and improving the matching efficiency. The dense disparity map is obtained by minimizing the energy function. In experiments with the international standard Middlebury platform, the results show that the proposed algorithm gets matching with high precision, high speed, low mismatch, and high matching efficiency..
Laser & Optoelectronics Progress
- Publication Date: Sep. 12, 2014
- Vol. 51, Issue 10, 101001 (2014)
Imaging Systems
Optical System Design of High Definition Video Telephoto Objective and Its Imaging Experiment
Gao Xingyu, Yu Daoyin, Long Yue, and Xiao Zexin
In order to satisfy the remote detection requirements for the surface defects on the cables of cable stayed bridges, an opto- mechanical system of a high definition video telephoto objective is designed and manufactured. According to the objective definition requirement of 4 mm at the distance of 300 m, the imaging defIn order to satisfy the remote detection requirements for the surface defects on the cables of cable stayed bridges, an opto- mechanical system of a high definition video telephoto objective is designed and manufactured. According to the objective definition requirement of 4 mm at the distance of 300 m, the imaging definition of 234 cycle/mm with a focal length of 320 mm is determined. A proper initial configuration is chosen, and then some optimization procedures are carried out with the optics design program OSLO, including the focus zooming, glass exchanging, lens reduction, etc. Finally an optical configuration of the telephoto objective is obtained with the relative aperture of 1/5.7, the field angle of 2 ω =1.379°, and the definition of 250 cycle/mm. The opto- mechanical structures are designed rationally and the experimental objective is manufactured. The definition testifies that its actual objective definition reaches 4 mm at the distance of 300 m. The site imaging experiment results at the location of a cable stayed bridge show that this system satisfies the remote detection requirements for the surface defects on the real engineering structures..
Laser & Optoelectronics Progress
- Publication Date: Sep. 03, 2014
- Vol. 51, Issue 10, 101101 (2014)
Instrumentation, Measurement and Metrology
Investigation of the Optimal Light Condition on Digital Image Correlation Method
Yu Zhijing, and Tao Hongwei
The effect of lighting conditions on digital speckle correlation method (DSCM) measurement accuracy is researched, and the optimal parameters and light condition for digital speckle correlation calculation are obtained. Through theoretical analysis of the model of DSCM, the relational expression of error about the freqThe effect of lighting conditions on digital speckle correlation method (DSCM) measurement accuracy is researched, and the optimal parameters and light condition for digital speckle correlation calculation are obtained. Through theoretical analysis of the model of DSCM, the relational expression of error about the frequency and average gray gradient is obtained. The optimal digital speckles size, fitting window size and calculation window size are got with computer simulation of digital speckle image. Leading into the technology of GSI in physical experiment, the accurate displacement is got and the error of different light conditions is analyzed, finding the connection about light with the frequency and average gray gradient through studying the digital speckle images. Experiments show that 8000 lx is the optimal light condition in DSCM, when average gray gradient is high and DSCM measurement is precision..
Laser & Optoelectronics Progress
- Publication Date: Aug. 25, 2014
- Vol. 51, Issue 10, 101201 (2014)
A Phase Encoding Modulation Method to Increase the Longitudinal Correlation of Speckle Fields
Cai Huaiyu, Jiao Mengjin, Huang Zhanhua, and Guo Zhendong
The axial decorrelation of speckle patterns is one of the key problems which restrict the use of speckle interferometry. A method of speckle field phase encoding modulation is proposed to increase the speckle longitudinal correlation so that the contrast of the speckle interference fringes can be improved, and then theThe axial decorrelation of speckle patterns is one of the key problems which restrict the use of speckle interferometry. A method of speckle field phase encoding modulation is proposed to increase the speckle longitudinal correlation so that the contrast of the speckle interference fringes can be improved, and then the measurement range of the object surface deformation can be extended. The wavefront coding technique is used to code the speckle fields and a cubic phase mask is set at the position of aperture. The feasibility of this method in increasing the longitudinal correlation of speckle fields is analyzed firstly. The effect that the cubic phase mask in the 4f system can effectively increase the longitudinal correlation of coded speckle field is validated by simulation and experiment respectively. The results show that the longitudinal speckle size increases from 0.17 mm to 0.4 mm and increases by about 2.5 times..
Laser & Optoelectronics Progress
- Publication Date: Aug. 28, 2014
- Vol. 51, Issue 10, 101203 (2014)
OpenGL Simulation for 3-CCD Target Positioning System
Song Wei, Li Xiaolei, Zhang Ya′nan, Shen Linyong, Zhao Dongfeng, and Shao Ping
To improve the operating efficiency of high power laser facility project, a simulation system using “OpenGL”graphics software is built to evaluate the target positioning algorithm at the debugging phases, which is independent on unperfect hardware experimental environment. The proposed positioning method calculates theTo improve the operating efficiency of high power laser facility project, a simulation system using “OpenGL”graphics software is built to evaluate the target positioning algorithm at the debugging phases, which is independent on unperfect hardware experimental environment. The proposed positioning method calculates the target's spatial coordinate and rotational angles by integrating the feature values abtained by three CCDs， and adjusts the target-sending mechanism to put the target in a desired position. The simulation results show the target-sending mechanism is confirmed to be able to adjust the target in a desired position based on the measurement results, which verifies the practicality of the proposed positioning algorithm to be used in the real ICF physical experiment..
Laser & Optoelectronics Progress
- Publication Date: Sep. 09, 2014
- Vol. 51, Issue 10, 101204 (2014)
Lasers and Laser Optics
Analysis of the Mechanism Cracking During the Multipass Laps Cladding Experiment
Chen Lie, Tao Ran, Lou Deyuan, Wu Ying, and Yang Qibiao
The mechanism and conditions giving rise to cracking during multipass laps laser cladding are investigated by finite element analysis software. Numerical analysis, combined with experimental observations, is also utilized. Calculations reveal that tensile stress is brought inside the cladding layer, and is mostly conceThe mechanism and conditions giving rise to cracking during multipass laps laser cladding are investigated by finite element analysis software. Numerical analysis, combined with experimental observations, is also utilized. Calculations reveal that tensile stress is brought inside the cladding layer, and is mostly concentrated at the boundary of the substrate and the bottom of the layer. Thus, a tendency to crack takes place perpendicular to the laser scanning direction. In addition, preheating improves the process by reducing the thermal stresses in the first cladding. After cladding the parts twice, the stress of the cladding layer is decreased more rapidly than the stress of the scanning direction. Cracking is formed at a certain angle to the scanning direction. The reliability and the accuracy of the model are experimentally verified..
Laser & Optoelectronics Progress
- Publication Date: Aug. 28, 2014
- Vol. 51, Issue 10, 101401 (2014)
Research on 3-Ray Automatic Alignment in High Power Excimer Laser MOPA System
Qian Hang, Wang Dahui, Ma Lianying, Zhang Yongsheng, Zhao Xueqing, Zhu Yongxiang, and Yi Aiping
Automatic alignment of laser beam is an important part of the large laser device. Taking classical imagerelaying unit in an excimer (XeCl) laser master oscillator power-amplifier (MOPA) system as an example, the establishment of alignment benchmark, the automatic alignment principle of 3-ray and charge-coupled device (Automatic alignment of laser beam is an important part of the large laser device. Taking classical imagerelaying unit in an excimer (XeCl) laser master oscillator power-amplifier (MOPA) system as an example, the establishment of alignment benchmark, the automatic alignment principle of 3-ray and charge-coupled device (CCD) image acquisition and processing method are introduced. It has been proved by the experiment results that this alignment unit can appease the request of laser automatic alignment of MOPA system..
Laser & Optoelectronics Progress
- Publication Date: Aug. 25, 2014
- Vol. 51, Issue 10, 101403 (2014)
Machine Vision
A New Method for Machine Vision Calibration and Rectification Based on LabVIEW
Shi Kang, Ye Hong, Hu Ancan, Zhou Lei, and Sun Yu
Calibration and rectification for the computer vision sensor are the key links of the application of machine vision system which will make the image more accurate so as to impove detection precision of the machine vision system. It is a key step that can not be ignored. An improved planar template method is presented, Calibration and rectification for the computer vision sensor are the key links of the application of machine vision system which will make the image more accurate so as to impove detection precision of the machine vision system. It is a key step that can not be ignored. An improved planar template method is presented, which extends the tangential distortion model based on the traditional method and the Heikkila model. The imaging model increases the high order nonlinear distortion and has some simplification.Through the model calibration parameters optimized and characteristics of the pixel space rectification value are obtained. The pixel grayscale is corrected by the linear interpolation method, the calibration results and the corrected image can be obtained. The method is implemented through LabVIEW tools in the machine vision detection platform built by the authors. Experiment verifies that images collected by the visual system are corrected well and the rectification accuracy reaches 0.17%..
Laser & Optoelectronics Progress
- Publication Date: Sep. 09, 2014
- Vol. 51, Issue 10, 101501 (2014)
Materials
A New Simplified Parameter Designing Method for Metamaterial Amplifying Device
Liang Yan, Li Tinghua, Huang Ming, Yang Jingjing, and Yuan Gang
Metamaterial amplifying device can make an object enlarged as one desire, and its potential application to small object identification and detection is foreseeable. To facilitate the practical application of such a device, a new simplified parameter designing method is proposed through choosing appropriate transformatiMetamaterial amplifying device can make an object enlarged as one desire, and its potential application to small object identification and detection is foreseeable. To facilitate the practical application of such a device, a new simplified parameter designing method is proposed through choosing appropriate transformation equation based on the theory of transformation optics. The virtues of such a method are that not only the radial and azimuthal parameters are constants and only axial parameter varies with radius, but also, there exist no undesired reflections due to perfect impedance matching to free space at outer boundary. Fullwave simulations confirm the effectiveness of the proposed method and the good performance of the designed amplifying device. Moreover, the effects of material loss and parameter deviation on the performance of the device are also investigated. This work expands the application of transformation optics, and also provides a new and feasible solution to simplify the parameters of metamaterial devices..
Laser & Optoelectronics Progress
- Publication Date: Aug. 25, 2014
- Vol. 51, Issue 10, 101601 (2014)
Study on a Novel Frequency Selective Surface Element
Zhu Huaxin, Guo Ying, Li Shuai, and Sun Yajun
Based on the ring loop element, a new element which sets a dipole slot in the ring loop element is introduced. The new combining element frequency selective surface (FSS) structure is calculated Galerkin's method in the spectral domain. The transmittance of both transverse electric wave (TE wave) and transverse magBased on the ring loop element, a new element which sets a dipole slot in the ring loop element is introduced. The new combining element frequency selective surface (FSS) structure is calculated Galerkin's method in the spectral domain. The transmittance of both transverse electric wave (TE wave) and transverse magnetic wave (TM wave) at skew angle incidence of 30° and 45° is high at about 11.5 GHz. But it also exhibits polarization splitter at about 14 GHz..
Laser & Optoelectronics Progress
- Publication Date: Aug. 22, 2014
- Vol. 51, Issue 10, 101602 (2014)
Tamm States Bandgap of One-Dimensional Sinc Function Photonic Crystals
Wang Yun
The formulas of reflection coefficient, transmission coefficient, electric and magnetic fields of onedimensional sinc function photonic crystals are deduced by the transfer matrix method on the condition of oblique incidence of the transverse magnetic (TM) wave. On this basis, a heterojunction composed of two semifinitThe formulas of reflection coefficient, transmission coefficient, electric and magnetic fields of onedimensional sinc function photonic crystals are deduced by the transfer matrix method on the condition of oblique incidence of the transverse magnetic (TM) wave. On this basis, a heterojunction composed of two semifinite photonic crystals is analyzed in detail. It is found that the semi- infinite photonic crystals on both sides of the heterostructure are equivalent to the negative permittivity materials or the negative permeability materials. Under the matching conditions, Tamm states emerge. By reducing the ratio of the optical thickness of the two dielectric layers, the first bandgap of TM or TE wave is significantly widened, and blueshift occurs for the position of the first bandgap. When refractive indices of the two media are increased in the same magnification, width of the first bandgap of TM or TE wave changes in the opposite directions, the former is gradually widened, the latter is narrowed, and redshift occurs for the position of the first bandgap. Transmission spectrum of the heterojunction is also significantly affected by the cycle number and angle of incidence..
Laser & Optoelectronics Progress
- Publication Date: Jul. 02, 2014
- Vol. 51, Issue 10, 101603 (2014)
Optical Design and Fabrication
Design of Optical Zoom System for Space Link Simulator
Tian Yuan, and Yan Changxiang
To achieve the laboratory performance test to laser communication system terminal, an optical method to simulate the laser transmission in different distances is required to use in the laboratory. In this paper, the primary design index of a link attenuation system is extracted according to the parameters of the front To achieve the laboratory performance test to laser communication system terminal, an optical method to simulate the laser transmission in different distances is required to use in the laboratory. In this paper, the primary design index of a link attenuation system is extracted according to the parameters of the front Fourier- transform lens. This paper cleverly makes use of the thoughts of optical enlargement and cascaded zoom system according to the index. The simulation to space links with variable distances is realized. A simulator system which can realize 3~10 times continuous zooming of a single-stage is designed, optimized by using ZEMAX, and the zoom curve of a single- stage is drawn. The structure of single- stage system with length of 309 mm is compact. The wavefront aberration of the whole field is better than 0.05 λ . The energy of light is concentrated. Through theoretical analysis, four cascaded design can achieve equivalent transmission distance of 103~105 km, so as to satisfy the detection requirements for most of the laser communication terminals..
Laser & Optoelectronics Progress
- Publication Date: Sep. 09, 2014
- Vol. 51, Issue 10, 102202 (2014)
Design of a Vehicle-Mounted Camera Lens
Zhu Junyan, and Ding Guiling
In order to meet the needs of the backing-up lens in cars, a wide-angle lens has been designed. The lens has four elements, the first is a piece of optical glass, the other 3 elements are plastic, and the lens is able to work under bad conditions. The lens has an F number of 2.8, the horizontal field is 185 degrees, anIn order to meet the needs of the backing-up lens in cars, a wide-angle lens has been designed. The lens has four elements, the first is a piece of optical glass, the other 3 elements are plastic, and the lens is able to work under bad conditions. The lens has an F number of 2.8, the horizontal field is 185 degrees, and the test showes that the off-axial distortion is corrected perfectly. Mass production of the lens has begun..
Laser & Optoelectronics Progress
- Publication Date: Sep. 09, 2014
- Vol. 51, Issue 10, 102203 (2014)
Research on Compensation of Computer Controlled Polishing Aspheric Surface-Shape Error
Xu Haihua
When the traditional method is used for polishing high- precision aspheric surface, the time consumption of surface- shape error compensation is more than 80% of the total polishing time. The efficiency of aspheric surface machining is severely affected. According to the principle of compensation for aspherical surfaceWhen the traditional method is used for polishing high- precision aspheric surface, the time consumption of surface- shape error compensation is more than 80% of the total polishing time. The efficiency of aspheric surface machining is severely affected. According to the principle of compensation for aspherical surface- shape error, process experiments of error compensation of polishing surface figure is conducted. By calculation and compensation of aspherical surface- shape using the software LOH- data- correct, the times of surface-shape correction and the cost are reduced, the machining efficiency is improved..
Laser & Optoelectronics Progress
- Publication Date: Sep. 05, 2014
- Vol. 51, Issue 10, 102204 (2014)
Optical Devices
Design of Surface Plasmon Dichroic Splitter with Two Metallic Slits
Wang Jicheng, Liu Hongjiao, Cai Zengyan, Wu Tao, Zhang Yuchan, Du Minghan, and Xu Yiping
The model of plasmonic dichroic splitter in metal-insulator-metal (MIM) stucture with two subwavelength metallic slits is proposed in theory. The different visible lights passing through the double slits subwavelength structure produce optical splitting effects by filling with different insulators and setting the slit The model of plasmonic dichroic splitter in metal-insulator-metal (MIM) stucture with two subwavelength metallic slits is proposed in theory. The different visible lights passing through the double slits subwavelength structure produce optical splitting effects by filling with different insulators and setting the slit width, double slits width and thickness of the waveguide structure of double slit. The splitting effects are explained by using surface plasmon′ s principle and classical optics interference principle. Finite-difference time-domain (FDTD) method is adopted for numerical simulation. We simulate the light filed distribution in two cases of double slits with the same width filled in different insulators and the double slits with different width filled in same insulators. Both cases can achieve ideal splitting effects, and the biggest splitting ratio is 12. The MIM design has the advantage of simple structure, can be obtained by electron beam lithography system experiment equipment. Therefore, it has good application value..
Laser & Optoelectronics Progress
- Publication Date: Sep. 09, 2014
- Vol. 51, Issue 10, 102301 (2014)
Physical Optics
Propagation Properties of Hermite-Cosine-Gaussian Beams in Gradient-Index Medium
Huang Yongchao, Cai Dafeng, and Zhang Tingrong
Using generalized Huygens-Fresnel diffraction integration, the analytical expression of Hermite-Cosine-Gaussian beams propagating in a gradient-index medium is deduced, and the influence of the gradientindex medium on the propagation properties of Hermite-Cosine-Gaussian beams with this expression is discussed for digiUsing generalized Huygens-Fresnel diffraction integration, the analytical expression of Hermite-Cosine-Gaussian beams propagating in a gradient-index medium is deduced, and the influence of the gradientindex medium on the propagation properties of Hermite-Cosine-Gaussian beams with this expression is discussed for digital simulation. The results show that when Hermite-Cosine-Gaussian beams propagating in a gradient-index medium, axial intensity emerges spatially cyclical changes and maximum intensity position is related to gradient-index factor β . With the increase of the modulation parameter α , axis maximum intensity decreases and the hollow distribution emerges. In the same propagating plane, with the increasing of the gradient index parameter β , the transmitted intenisty increases at first but then decreases rapidly. And with the increase of α , intensity strength keeps unchanged, but waist width becomes narrowed..
Laser & Optoelectronics Progress
- Publication Date: Aug. 29, 2014
- Vol. 51, Issue 10, 102601 (2014)
Remote Sensing and Sensors
A Gaussian Inflexion Points Matching Method for Gaussian Decomposition of Airborne LiDAR Waveform Data
Duan Yihao, Zhang Aiwu, Liu Zhao, Wang Shumin, Wang Jingmeng, and Ye Qiuhong
Estimation of Gaussion components′ number is a core problem in the procedure of Gaussian decomposition of small- footprint full- waveform airborne LiDAR waveform data. A new approach named Gaussian inflexion points matching method (GIPM) is proposed to solve it. GIPM algorithm uses the quick locating algorithm for turnEstimation of Gaussion components′ number is a core problem in the procedure of Gaussian decomposition of small- footprint full- waveform airborne LiDAR waveform data. A new approach named Gaussian inflexion points matching method (GIPM) is proposed to solve it. GIPM algorithm uses the quick locating algorithm for turning points in discrete point set of plane curve (QLATP) method for detecting the inflexion points (IFPs). The slope of the line between the detected IFP and its adjacent point is calculated. The detected IFPs are classified as left IFPs and right IFPs according to the slope. A left IFP and its neighboring right IFP comprise a Gaussian component, thus getting the number of the Gaussian components of waveform data. GIPM method is used to decompose the simulated and the measured waveform data, comparing with two traditional pulses detection method (center of gravity and Gaussian pulse fitting). The results demonstrate that the GIPM method can tremendously retain the impact of the pseudo IFPs, and quickly and accurately detect and decompose Gaussian components of the waveform data, and then immensely speed up the decomposition of waveform data. Meanwhile, it can get more Gaussian components than others, thus improving the density of point cloud..
Laser & Optoelectronics Progress
- Publication Date: Sep. 12, 2014
- Vol. 51, Issue 10, 102801 (2014)
Reviews
Laser-Induced Breakdown Spectroscopy for Analysis of Liquids
Yang Liu, Chen Yanping, Xu Jianqiu, and Sheng Zhengming
Following a brief introduction of the principle of laser-induced breakdown spectroscopy (LIBS), the recent technical development and its application in liquid samples are reviewed. The merits and drawbacks of different forms of samples, such as liquid bulk, liquid surface, liquid jets, aerosols and solidifying solvent,Following a brief introduction of the principle of laser-induced breakdown spectroscopy (LIBS), the recent technical development and its application in liquid samples are reviewed. The merits and drawbacks of different forms of samples, such as liquid bulk, liquid surface, liquid jets, aerosols and solidifying solvent, are compared. Much effort in this technique development is devoted to the improvement of the limit of detection (LOD) of liquid elements. Due to its advantages such as online and rapid detection, the LIBS technique of liquid is supposed to have great potential of applications in many areas, such as environment detection, waste water treatment, biological medicine, industrial control, etc..
Laser & Optoelectronics Progress
- Publication Date: Sep. 12, 2014
- Vol. 51, Issue 10, 100001 (2014)
Research Advances in Optical Fiber Current Sensor Technology
Wang Zhi, and Chu Fenghong
Power system protection for current measurement and sensor technology have become increasingly demanding. The traditional electromagnetic transformer is unable to meet the requirements. Since the advent of fiber-optic current sensors, researches have focused on how to reduce the influence of birefringence and temperatuPower system protection for current measurement and sensor technology have become increasingly demanding. The traditional electromagnetic transformer is unable to meet the requirements. Since the advent of fiber-optic current sensors, researches have focused on how to reduce the influence of birefringence and temperature. Based on the research status of the existing literature on the field of fiber-optic current sensors, new developments, new technologies, nearest discoveries and development prospects, a comprehensive collaction and analysis is given, and the progress of fiber-optic current sensors is shown in detail..
Laser & Optoelectronics Progress
- Publication Date: Aug. 22, 2014
- Vol. 51, Issue 10, 100002 (2014)
Research Progress of Effect of High Power Signal on Optical Networks and Protection Technology
Zhang Yinfa, Ren Shuai, Wang Peng, Li Ming, and Wang Jingyu
In recent years optical networks are developing towards high rate and wide bandwidth. Optical networks propagate a great amount of information, and its security issues are drawing more and more attention. Impact of high power signal on optical networks and protection technology has become a hotspot for research in the In recent years optical networks are developing towards high rate and wide bandwidth. Optical networks propagate a great amount of information, and its security issues are drawing more and more attention. Impact of high power signal on optical networks and protection technology has become a hotspot for research in the area of security of optical networks. Gain competition attack, inter-channel crosstalk attack, and intrachannel crosstalk attack caused by high power signal in optical networks are introduced, and attack impact caused by high power signal on legitimate signals in optical networks is also analyzed. Security protection technologies aiming at attack impact of high power signal in optical networks are summarized from the viewpoints of attack detection and location technology, secure routing protection technology and other protection technologies..
Laser & Optoelectronics Progress
- Publication Date: Aug. 22, 2014
- Vol. 51, Issue 10, 100003 (2014)
Spin and Orbital Angular Momentum of Light
Wei Gongxiang, Liu Xiaojuan, Liu Yunyan, and Fu Shenggui
Spin angular momentum (SAM) and orbital angular momentum (OAM) are two absolutely different physical properties of light which are determined by the polarization and spatial distribution, respectively. The comparison of the two properties is performed in terms of demonstrated about the generation and conversion, existeSpin angular momentum (SAM) and orbital angular momentum (OAM) are two absolutely different physical properties of light which are determined by the polarization and spatial distribution, respectively. The comparison of the two properties is performed in terms of demonstrated about the generation and conversion, existence form and description method, mechanical effect, spatial and time coherence, angular Doppler effect, parameter conversion and quantum entanglement, etc. The phenomenology provides much of the basis for the exploration and exploitation of the field. The progress of OAM development with an eye towards the promising future in the field is reviewed and analyzed..
Laser & Optoelectronics Progress
- Publication Date: Aug. 20, 2014
- Vol. 51, Issue 10, 100004 (2014)
Design of“Solar Blind”Ultraviolet Zoom Optical System Used in Corona Detection
Zhang Hongjia, Ma Jun, Zhu Haiyu, and Wang Wensheng
According to the requirements of corona detection on searching targets with large field of view and detecting objects with small field of view, a refractive zoom optical system using mechanical compensation technology and working at“solar blind”ultraviolet wavelength (0.24~0.28 μm ) is designed. According to the requirAccording to the requirements of corona detection on searching targets with large field of view and detecting objects with small field of view, a refractive zoom optical system using mechanical compensation technology and working at“solar blind”ultraviolet wavelength (0.24~0.28 μm ) is designed. According to the requirements of users, the focal length spreads from 30 mm to 60 mm, and F number is 3.5. PIXIS 1024BUV CCD with size of 1 inch (1 inch=2.54 cm) and pixel size of 13 μm ×13 μm is used as a sensor. The field of view of the system is 8°~16°. The zoom lens consists of eight lenses with two aspherical surfaces, so it has the advantages of low cost and simple structure . The design results show that the modulation transfer function (MTF) of the zoom system is higher than 0.7 at cut off frequency of 38 lp/mm. The optical performance at all fields of view and all zooming conditions is close to the diffraction- limited image, and the distortion is less than 3% . So the zoom optical system presents a good image quality, and can meet users′ requirements..
Laser & Optoelectronics Progress
- Publication Date: Sep. 09, 2014
- Vol. 51, Issue 10, 102201 (2014)
Scattering
Investigation on the Scattering of Bessel Beam by an Eccentric Sphere
Chen Zhuyang, Han Yiping, Cui Zhiwei, and Shi Xiaowei
In the framework of the general Lorenz-Mie theory, the scattering of an on-axis incident zero-order Bessel beam by an eccentric sphere is investigated. The electric and magnetic fields in different regions are expanded in terms of the sphere vector wave functions. Utilizing the boundary conditions of electromagnetic fiIn the framework of the general Lorenz-Mie theory, the scattering of an on-axis incident zero-order Bessel beam by an eccentric sphere is investigated. The electric and magnetic fields in different regions are expanded in terms of the sphere vector wave functions. Utilizing the boundary conditions of electromagnetic field, the expressions of expansion coefficient equations are given. Numerical simulations about the effect of Bessel beam half- angle, eccentricity, refractive index of inner sphere, radius of inner sphere on scattering are analyzed in detail..
Laser & Optoelectronics Progress
- Publication Date: Sep. 09, 2014
- Vol. 51, Issue 10, 102901 (2014)
Spectroscopy
Influence of Soil Porosity on Characteristics of Laser-Induced Soil Plasmas
Lu Cuiping, Wang Liusan, Liu Jing, Song Liangtu, and Wang Rujing
The influence of soil porosity on characteristics of laser-induced breakdown spectroscopy (LIBS) of metal element Pb in soil is measured and analysed, using Nd:YAG (wavelength of 1064 nm) laser as the excitation source to induce soil plasma in the natural environment of the laboratory. The experimental results show thaThe influence of soil porosity on characteristics of laser-induced breakdown spectroscopy (LIBS) of metal element Pb in soil is measured and analysed, using Nd:YAG (wavelength of 1064 nm) laser as the excitation source to induce soil plasma in the natural environment of the laboratory. The experimental results show that the spectral line intensity and plasma temperature increase with porosity firstly, and then change slowly. The minimum relative standard deviation of the spectral intensity is at the pressure of 1400 N. The internal standard method and background correction method are used to correct the influence of soil porosity, to some extent, reducing the porosity of the soil..
Laser & Optoelectronics Progress
- Publication Date: Aug. 28, 2014
- Vol. 51, Issue 10, 103001 (2014)
Detection of Chlortetracycline Residues in Egg Albumen Using Silver Colloids Surface-Enhanced Fluorescence of Eu (III)
Peng Yijie, Liu Muhua, Zhao Jinhui, Yuan Haichao, Hong Qian, and Li Yao
Chlortetracycline residues in egg albumen areaccumulated easily in humanbody, resulting in producing harm to human body. According to the research, silver colloids can be used as surface substrate to modify complexes of chlortetracycline and Eu(III), which makes the fluorescence intensity of complexes enhanced significChlortetracycline residues in egg albumen areaccumulated easily in humanbody, resulting in producing harm to human body. According to the research, silver colloids can be used as surface substrate to modify complexes of chlortetracycline and Eu(III), which makes the fluorescence intensity of complexes enhanced significantly. Silver colloids surface- enhanced fluorescence of Eu(III) is applied to detect chlortetracycline residues in egg albumen. Different addition amount of colloid and Eu(III), reaction time and other factors which have influence on fluorescence intensity are analyzed respectively in the research. The best experimental conditions are determined, and the calibration curve under the optimum condition is established between the fluorescence intensity of characteristic peak at 617 nm (Y) and chlortetracycline content (X). The results show that a good linearity is obtained between the fluorescence intensity and chlortetracycline concentration in egg albumen in the range of 1.5~29.5 mg/L. The linear function is Y=5.2265 + 24.033 X, and the determination coefficient is 0.9043. The determination coefficient between the measured values and predicted values is 0.9182. The results show that it is feasible to use silver colloids surface- enhanced fluorescence of Eu(III) to detect chlortetracycline residues in egg albumen rapidly..
Laser & Optoelectronics Progress
- Publication Date: Sep. 03, 2014
- Vol. 51, Issue 10, 103002 (2014)
Research on the Method to Select Internal Standard Reference for Laser-Induced Breakdown Spectroscopy
Shang Liping, Li Wenhong, Wu Zhixiang, Wang Ruiwen, and Zhou Qiang
The internal standard method is one of the main methods used in laser-induced breakdown spectroscopy (LIBS) for quantitative analysis. The key of the internal standard method for quantitative analysis is the internal reference selection. Fe 438.35 nm is selected as the analytical line. Area of 434~441 nm、Al 309.29 nm、SThe internal standard method is one of the main methods used in laser-induced breakdown spectroscopy (LIBS) for quantitative analysis. The key of the internal standard method for quantitative analysis is the internal reference selection. Fe 438.35 nm is selected as the analytical line. Area of 434~441 nm、Al 309.29 nm、Si 288.17 nm、 Ca 317.9 nm are selected as internal standard parameters for quantitative analysis of Fe in cement samples. The correlation coefficients of calibration curves are 0.993、0.962、0.992 and 0.846，respectively. By analyzing the intensity ratio of each internal standard element and Fe 438.35 nm at different delay time, as well as the dispersion of multiple measurement data of each internal standard element, it is obtained that when LIBS is used for quantitative analysis with internal standard method, the internal standard element which has similar changes to the analytical spectral line in the vicinity of delay time should be choosen. This can effectively decrease the quantitative analysis error caused by laser jitter and improve the accuracy of quantitative analysis..
Laser & Optoelectronics Progress
- Publication Date: Sep. 05, 2014
- Vol. 51, Issue 10, 103003 (2014)
Thin Films
Upper Surface Anti-Reflection Coating on Crystalline Silicon Solar Cell
Zhou Tao, Lu Xiaodong, Li Yuan, Zhang Peng, and Zhang Ming
Single- and double-layer anti-reflection coatings with many kinds of common dielectric coat materials are designed and optimized based on the transfer matrix method (TMM). A two-dimensional crystal line silicon solarcell structure model based on different anti-reflect coatings is established using Silvaco ATLAS device Single- and double-layer anti-reflection coatings with many kinds of common dielectric coat materials are designed and optimized based on the transfer matrix method (TMM). A two-dimensional crystal line silicon solarcell structure model based on different anti-reflect coatings is established using Silvaco ATLAS device simulation software. The effect of light absorption is analyzed and evaluated by comparing the spectral responses of cells with different single and double-layer anti-reflection coatings. The results show that the crystalline silicon solar cell with double- layer anti- reflection coatings has more effective absorption spectrum when the wavelength range is from 200 nm to 1100 nm. Compared with single- layer anti- reflection coatings, the double layers composed of different dielectric materials have smaller light reflection loss, the double-layer coatings can reduce the loss of the spectral response effectively, and its performance is better than single-layer coatings. MgF2/ZnS double-layer coatings have the best anti-reflection effect and the light reflectance can be reduced to lower than 5% for the incident light with wavelengths of 380~1000 nm..
Laser & Optoelectronics Progress
- Publication Date: Sep. 05, 2014
- Vol. 51, Issue 10, 103101 (2014)
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