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2011
Volume: 48 Issue 7
27 Article(s)
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Research Article
Optical Thin Film Design Based on Multi-Objective Genetic Algorithm
Wang Peixia, and Jia Yuqin
At present, nearly all optimization methods used for optical thin film design can seek only one object, which is difficult to meet the complex needs of optical thin films. So, the multi-objective optimization model of optical thin film and a new multi-objective genetic algorithm (DMOGA) are proposed. In DMOGA, a methodAt present, nearly all optimization methods used for optical thin film design can seek only one object, which is difficult to meet the complex needs of optical thin films. So, the multi-objective optimization model of optical thin film and a new multi-objective genetic algorithm (DMOGA) are proposed. In DMOGA, a method based on non-dominated relationship is used in choosing operator. Solution with qualified distributivity and approximation by shrink of the population of non-dominated set is achieved based on dynamic crowding distance and the algorithm parameters are adjusted dynamically to improve the efficiency of algorithm. Some examples of optical thin film designs are solved by DMOGA. The results show that DMOGA is a useful algorithm for multi-objective problems and may have a bright future in optical thin film design..
Laser & Optoelectronics Progress
- Publication Date: May. 20, 2011
- Vol. 48, Issue 7, 73101 (2011)
Atmospheric Optics and Oceanic Optics
Polarization of Light Scattering by Ice-Water Mixed Clouds in Visible Regions
Wang Haihua, Sun Xianming, and Liu Wanqiang
Based on the Mie theory, the light scattering properties (single scattering albedo, asymmetry parameters, and single scattering phase matrix) in the visible regions of clouds consisting of pure water, pure ice spheres and concentric water-ice spheres are computed respectively. The reflection matrixes of the three typesBased on the Mie theory, the light scattering properties (single scattering albedo, asymmetry parameters, and single scattering phase matrix) in the visible regions of clouds consisting of pure water, pure ice spheres and concentric water-ice spheres are computed respectively. The reflection matrixes of the three types of clouds are evaluated with the adding-doubling method by solving the radiative transfer equation. The reflection characteristics of different light wavelengths are compared. The numerical results show that the polarization degree of reflected light is more sensitive to the particle microphysics characteristics than the intensity of reflected light..
Laser & Optoelectronics Progress
- Publication Date: May. 09, 2011
- Vol. 48, Issue 7, 70101 (2011)
Multiple Scattering Model and Simulation for Non-Line-of-Sight Communication
Song Chao, Xu Zhiyong, and Wang Jingyuan
The theoretic expressions of loss in different scattering orders are analysed by imitating random migrations of photons in free space. The predicted path loss under different elevation angles are presented and compared with relevant literature to validate it. It can be concluded from the simulation that under specific The theoretic expressions of loss in different scattering orders are analysed by imitating random migrations of photons in free space. The predicted path loss under different elevation angles are presented and compared with relevant literature to validate it. It can be concluded from the simulation that under specific preferences, high orders of scattering (higher than four orders) contribute little to the total energy of received optical signal (at least 10 orders of magnitude smaller), and thus the effects caused by the 4th or higher orders of scattering can be neglected..
Laser & Optoelectronics Progress
- Publication Date: May. 09, 2011
- Vol. 48, Issue 7, 70102 (2011)
Detectors
Influence Analysis of Detector Dynamic-Range on Laser Beam Quality Factor β Measurement
Guan Youguang, Zhou Wenchao, and Tian Xiaoqiang
Based on the far field distribution character of high energy laser, the influence of different dynamic-range detectors in laser beam quality factor β measurement is discussed. According to numerical calculation of different dynamic-range detectors in the diffraction limit beam quality measurement, the lowest value of dBased on the far field distribution character of high energy laser, the influence of different dynamic-range detectors in laser beam quality factor β measurement is discussed. According to numerical calculation of different dynamic-range detectors in the diffraction limit beam quality measurement, the lowest value of dynamic-range is recommended. The experiment demonstrates the correctness of simulation result..
Laser & Optoelectronics Progress
- Publication Date: Jun. 02, 2011
- Vol. 48, Issue 7, 70401 (2011)
Diffraction and Gratings
Spatial Beam Shaping Realized by Annular Phase Pupil Filter
Wang Wei
At the condition of high numerical aperture, optical intensity distribution near the focus must be analyzed by vector diffraction theory. According to vector diffraction method, three-zone annular phase pupil filters are simulated to realize beam shaping. Through the numerical simulation of objective focus area light iAt the condition of high numerical aperture, optical intensity distribution near the focus must be analyzed by vector diffraction theory. According to vector diffraction method, three-zone annular phase pupil filters are simulated to realize beam shaping. Through the numerical simulation of objective focus area light intensity distribution with 0.85 numerical aperture, three-zone annular phase structure can be realized by using optimal search algorithm. The results indicate that flat-top beam shaping and single-circle beam shaping at the focal plane can all be realized by using three-zone annular phase pupil filters. The influence of normalized radius and changing phase on beam shaping quality is analyzed. Further more, changing the radii of three rings can control the radius of diffraction single-circle and the strength of focus intensity..
Laser & Optoelectronics Progress
- Publication Date: May. 05, 2011
- Vol. 48, Issue 7, 70501 (2011)
Fiber Optics and Optical Communications
Application of Thermal Analysis on Reliability Design of Optoelectronic Modules
Song Beili, Yang Dian, Zhao Xianming, and Xu Hongchun
Components of counting method is the general method of the reliability design of optoelectronic modules at home and abroad. In order to improve the problem that no mature optoelectronic modules the reliability prediction can not be effectively carried out, in product design stage by using Flow Simulation softwar, and wComponents of counting method is the general method of the reliability design of optoelectronic modules at home and abroad. In order to improve the problem that no mature optoelectronic modules the reliability prediction can not be effectively carried out, in product design stage by using Flow Simulation softwar, and working status of XFP (10G small form factor pluggable) module, for example, is simulation analyzed under different temperature conditions. The thermal analysis of XFP module is finished, and the optimization approach of the reliability design of XFP module is given. Then the specifically quantified of the reliability prediction of XFP module and is expected, the quantitative analysis of reliability for optoelectronic modules in the design phase is achieved..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2011
- Vol. 48, Issue 7, 70602 (2011)
Acoustic Sensitivity of Interferometric Fiber-Optic Mandrel Hydrophone using Orthogonal Design
Shen Shuai, Zhou Hongpu, Zhang Min, and Liao Yanbiao
A L9 (34) orthogonal test is designed to investigate the effect of the room between the tube and the mandrel and the tension pulled on the fiber on acoustic sensitivity of interferometric fiber-optic mandrel hydrophone. Experimental results show that the room of air cavity and the tension pulled on fiber do not have muA L9 (34) orthogonal test is designed to investigate the effect of the room between the tube and the mandrel and the tension pulled on the fiber on acoustic sensitivity of interferometric fiber-optic mandrel hydrophone. Experimental results show that the room of air cavity and the tension pulled on fiber do not have much influence on sensitivity which can not be considered under the condition that the fiber and tube are fully coupled..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2011
- Vol. 48, Issue 7, 70603 (2011)
Image Processing
Robust Method for Moving Object Detection in Dynamic Background
Yu Xiaqiong, and Chen Xiangning
A robust approach to detect moving object in dynamic background is proposed. The feature descriptions are generated by scale invariant feature transform (SIFT) algorithm. Initial match set is obtained according to nearest neighbor distance ratio(NNDR) strategy, and a robust match set is obtained by using the constraintA robust approach to detect moving object in dynamic background is proposed. The feature descriptions are generated by scale invariant feature transform (SIFT) algorithm. Initial match set is obtained according to nearest neighbor distance ratio(NNDR) strategy, and a robust match set is obtained by using the constraint of symmetry. Random sample consensus(RANSAC) algorithm is applied to distinguish features in moving object region from the background. Based on background compensation, the moving object region is segmented by inter-frame difference and morphology operations. Experimental results on real video sequences from moving cameras demonstrate that the proposed algorithm can obtain a set of robust feature correspondences and detect moving object..
Laser & Optoelectronics Progress
- Publication Date: Jun. 02, 2011
- Vol. 48, Issue 7, 71001 (2011)
Imaging Systems
Interrelation Design for Improving Performance of Laser Active Imaging System
Zhao Yun, Li Yingchun, Sun Huayan, and Guo Huichao
Optical system and detector′s limit resolution are the main factors to influence the resolution of laser active imaging system. Modulation transfer function (MTF) is an important index to represent system performance. To improve imaging resolution and MTF, the interrelation of receiving optical system and detector sizeOptical system and detector′s limit resolution are the main factors to influence the resolution of laser active imaging system. Modulation transfer function (MTF) is an important index to represent system performance. To improve imaging resolution and MTF, the interrelation of receiving optical system and detector size is analyzed, and the design steps of optical system parameters are given. The matching condition and design procedure are proved by experiments..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2011
- Vol. 48, Issue 7, 71101 (2011)
Instrumentation, Measurement and Metrology
Surface Error Measurement of Plane Mirrors Based on Oblique Incidence
Ma Chuntao, Luo Hongxin, Wang Jie, and Song Li
In order to measure the surface shape of large aperture plane mirrors by using smaller caliber laser interferometer, oblique incidence method is developed. Thus, the spot illuminated on the tested mirror is magnified, and the size range that the interferometer can measure is much bigger. The plane mirror surface shape In order to measure the surface shape of large aperture plane mirrors by using smaller caliber laser interferometer, oblique incidence method is developed. Thus, the spot illuminated on the tested mirror is magnified, and the size range that the interferometer can measure is much bigger. The plane mirror surface shape expression based on oblique incidence is gained, and the errors that may be introduced are concerned. And a plane mirror with size of 124 mm×42 mm is measured using vertical incidence and oblique incidence with different incidence angles. The surface height root mean square (RMS) and peak-to-valley (PV) results of the test mirror are 16.3 nm and 67.8 nm based on vertical incidence and 16.8 nm and 68.7 nm based on oblique incidence. Compared with vertical incidence measurement results, the relative error value of RMS is 3%, and the relative error value of PV is 0.9%.The result can satisfy the requirement of the third generation synchrotron radiation beam lines..
Laser & Optoelectronics Progress
- Publication Date: May. 07, 2011
- Vol. 48, Issue 7, 71201 (2011)
Optimization Design of Acousto-Optical Gyroscope
Lu Shuxiang, Chen Shufen, Zou Zhengfeng, Fu Lei, and Meng Yanbin
Surface acoustic wave (SAW) gyroscopic effect is analyzed when a piezoelectric half-space rotates, and the change form of angular speed verus the wave velocity is obtained. Then the acousto-optic coupling wave equation is discussed, and the formula relationship of angular speed and the diffraction efficiency is gotten Surface acoustic wave (SAW) gyroscopic effect is analyzed when a piezoelectric half-space rotates, and the change form of angular speed verus the wave velocity is obtained. Then the acousto-optic coupling wave equation is discussed, and the formula relationship of angular speed and the diffraction efficiency is gotten in acousto-optic coupling situation. The optimization design to the acousto-optic gyroscope′s structure is carried on according to this relationship. The optimization design indicates that X cuts Y propagating and Z cuts Y propagating LiNbO3 crystal have the biggest scale factor, the sensitivity is usually the highest when the gyroscope rotates along SAW propagating direction, and the accuracy of this design is 2.06°/h, which is 2 orders of magnitude higher than that of normal SAW gyroscope..
Laser & Optoelectronics Progress
- Publication Date: Jun. 02, 2011
- Vol. 48, Issue 7, 71202 (2011)
Lasers and Laser Optics
Effect of Primary Spherical Aberration on Optical Trapping Force of Radially Polarized Beam
Li Donghua, Pu Jixiong, and Wang Xiqing
Based on Richards-Wolf vectorial diffraction method, we investigate the effect of primary spherical aberration on radiation forces of Rayleigh particles when a radially polarized beam is focused by a high numerical-aperture system. The distributions of radiation forces along axial direction varing with coefficient of sBased on Richards-Wolf vectorial diffraction method, we investigate the effect of primary spherical aberration on radiation forces of Rayleigh particles when a radially polarized beam is focused by a high numerical-aperture system. The distributions of radiation forces along axial direction varing with coefficient of spherical aberration are obtained through numerical calculations. The results show that when the primary spherical aberration is changed, influences reflect not only on the magnitude of the radiation forces, but also on the balance position and the valid area. These changes caused by positive and negative primary spherical aberration are not always in the same patterns. The positive spherical aberration makes the gradient forces shift from oposition to the positive direction of z axis while the negative spherical aberration makes the opposite shift. Under different numerical apertures, the ratio of aperture and waist length and particle radius, the influcences of primary spherical aberration on optical trapping force will change..
Laser & Optoelectronics Progress
- Publication Date: May. 05, 2011
- Vol. 48, Issue 7, 71401 (2011)
Theoretical Research on Coherent Anti-Stokes Raman Shifters of Stokes Seed Method in Raman Crystals
Lin Shaojie, Ding Shuanghong, Zhang Jun, and Wang Shumei
Based on the wave equation and stimulated Raman scattering (SRS) material equations, the normalized coupled-wave equations for solid-state coherent anti-Stokes Raman shifters are deduced by Stokes seed method to research the anti-Stokes conversion efficiency. The numerical calculations are carried out to illustrate theBased on the wave equation and stimulated Raman scattering (SRS) material equations, the normalized coupled-wave equations for solid-state coherent anti-Stokes Raman shifters are deduced by Stokes seed method to research the anti-Stokes conversion efficiency. The numerical calculations are carried out to illustrate the effects of variables on the performance of solid-state coherent anti-Stokes Raman shifters in the pulse pumping regime, and several curves are generated. These variables include the normalized Raman gain G, the normalized phase mismatch ΔK and the normalized amplitude of the Stokes seed beam ψs0. The values of these variables are estimated from these curves. The results show that the highest anti-Stokes conversion efficiency of 44% can be achieved by enhancing ψs0 when phase is matched. The anti-Stokes conversion efficiency of 40% can be achieved with the weak Stokes seed beam when the proper phase mismatch is chosen..
Laser & Optoelectronics Progress
- Publication Date: May. 07, 2011
- Vol. 48, Issue 7, 71402 (2011)
Side-Pumped Nd:YAG Laser of 86 W Quasi-Fundamental Mode Diode-Lasers
Liu Yonggang, Wang Baohua, Hou Wei, Lin Xuechun, and Li Jinmin
Side-pumped Nd:YAG lasers of 86 W quasi-fundamental mode diode-lasers is presented. In experiment, the Nd:YAG crystal with the dimensions of is side-pumped by diode-lasers from three directions. Convex mirrors are used to increase mode volume with a 90° rotator to compensate thermal depolarization. Right parameterSide-pumped Nd:YAG lasers of 86 W quasi-fundamental mode diode-lasers is presented. In experiment, the Nd:YAG crystal with the dimensions of is side-pumped by diode-lasers from three directions. Convex mirrors are used to increase mode volume with a 90° rotator to compensate thermal depolarization. Right parameters of cavity are acquired by experiments and stimulations. At last, the maximum output power of 86 W is achieved with M2<2. The changes of beam width of radia l and tangential polarization with the length of thermal lens are stimulated. Parameters of the laser are numerical calculated, which are in good agreement with the experimental results. right expanding and focusing system are designed, and the relationship between the laser beam waist position and input current is acquired..
Laser & Optoelectronics Progress
- Publication Date: May. 06, 2011
- Vol. 48, Issue 7, 71403 (2011)
Influences of Processing Parameters on Geometric Characterizations of Laser Cladding Forming 316L Stainless Steel
Huang Xiaowei, Xi Juntong, J. L. Lebrun, Elcheikh Hussam, and Courant Bruno
After years of development of laser cladding forming technology, it has made many successful industrial applications. However, how to control the process to achieve the best forming results? We need study the relationship between the processing parameters and the forming accuracy to find the ultimate best solution. We After years of development of laser cladding forming technology, it has made many successful industrial applications. However, how to control the process to achieve the best forming results? We need study the relationship between the processing parameters and the forming accuracy to find the ultimate best solution. We prepare the 316L stainless steel specimens using the laser cladding forming to investigate the influences of processing parameters on geometric characterizations. Five parameters are defined to describe the geometric characterization of single layer cross section, and then the measurement data is processed with the linear regression method to establish relations between processing parameters and defined parameters. In addition, the laser cladding parts prone to two types of typical defects: micro-cracks between grain boundaries and poor fusion defects between two layers..
Laser & Optoelectronics Progress
- Publication Date: Jun. 02, 2011
- Vol. 48, Issue 7, 71404 (2011)
Research on Slotted Verticality of Die-Board Laser Cutting
Si Lizhong
Slotted verticality of the die-board laser cutting is studied by using the NEL-A series high-power fast-flow axis CO2 laser and the SLCM-1225 numerical control machine. Based on geometric optics theory, possible paths of the incident light on the convex lens are discussed. The result shows that the small deviation of tSlotted verticality of the die-board laser cutting is studied by using the NEL-A series high-power fast-flow axis CO2 laser and the SLCM-1225 numerical control machine. Based on geometric optics theory, possible paths of the incident light on the convex lens are discussed. The result shows that the small deviation of the optical path is the main cause of the non-vertical slot, and a veiw is given that the verticality of the slot can be improved by shifting the convex lens. The testing results show that the horizontal movement of the convex lens can change the position of the energy center lines of the laser beam, thus change the direction of the the energy center lines of the focused beam, and then change the angle between the slot and the board surface..
Laser & Optoelectronics Progress
- Publication Date: Jun. 03, 2011
- Vol. 48, Issue 7, 71405 (2011)
Characteristic of Polarized Modes under Local Pumping in Two-Dimensional Random Medium
Liu Hai, Jin Hui, Lü Jiantao, Zhang Xiangjun, and Ren Zihui
Considering the share and competition on the inversed population between different polarized lightwaves, the spectral time evolution and the threshold of polarized modes under local pumping are investigated by simultaneously solving Maxwell′s equations and rate equations of electronic population for both transverse magConsidering the share and competition on the inversed population between different polarized lightwaves, the spectral time evolution and the threshold of polarized modes under local pumping are investigated by simultaneously solving Maxwell′s equations and rate equations of electronic population for both transverse magnetic (TM) and transverse electric (TE) modes. Results show that the lasing threshold of TM modes can be lower than that of TE modes when the radius of the local pumping region is suitably selected. The intensity peak of TE mode increases and then decreases quickly, which indicates that the TE mode is restrained gradually under local pumping when the local pumping region is quite small. The conclusions are different from the case of whole pumping..
Laser & Optoelectronics Progress
- Publication Date: May. 09, 2011
- Vol. 48, Issue 7, 71407 (2011)
Optimization of Laser Transmission Joining Process Parameters for Thermoplastic Using Response Surface Methodology
Jiang Minfeng, Xu Zhenkai, Liu Huixia, Li Pin, Song Xinhua, and Wang Kai
Laser transmission joining process has potential prospects in industry and medical areas because of its speed, precision, flexibility and strong environmental adaptability. Polycarbonate sheets are joined using laser transmission joining technology with Compact130/140 laser diode of Dilas. The joining process is optimiLaser transmission joining process has potential prospects in industry and medical areas because of its speed, precision, flexibility and strong environmental adaptability. Polycarbonate sheets are joined using laser transmission joining technology with Compact130/140 laser diode of Dilas. The joining process is optimized in response surface methodology. The interaction effect of key parameters including laser power, scanning speed, clamp pressure, scanning number on joint quality is researched. The results show that the interaction of laser power and scanning speed is relatively large. Increasing laser power, reducing scanning speed, increasing the mold clamping force and the scanning number can be helpful to the joint quality. The morphology of the joining area is observed with an optical microscope. Based on this research, process parameters of laser transmission joining of polycarbonate are obtained..
Laser & Optoelectronics Progress
- Publication Date: Jun. 20, 2011
- Vol. 48, Issue 7, 71408 (2011)
Materials
First-Principles Calculation on Optical Properties of Ca3Si4 Intermetallic Compound
Gao Ran, and Xie Quan
The bulk of Ca3Si4 is investigated by using first principles pseudo-potential calculations based on the density function theory. The results show that Ca3Si4 is a semiconducting material with an indirect band gap and the band gap is 0.372 eV. The valence bands of Ca3Si4 are mainly composed of Si 3p as well as 3s, the cThe bulk of Ca3Si4 is investigated by using first principles pseudo-potential calculations based on the density function theory. The results show that Ca3Si4 is a semiconducting material with an indirect band gap and the band gap is 0.372 eV. The valence bands of Ca3Si4 are mainly composed of Si 3p as well as 3s, the conduction bands are mainly composed of Ca 3d. The optical properties of Ca3Si4 are that the static dielectric constant is 19, the refractive index is 4.35, the absorption coefficient maximum is 1.56×105 cm-1, and the value of the loss function becomes maximum at 8.549 eV..
Laser & Optoelectronics Progress
- Publication Date: May. 07, 2011
- Vol. 48, Issue 7, 71601 (2011)
Medical Optics and Biotechnology
Time-Resolved Monte Carlo Simulation for Optical Properties of Tissues
Ye Jingzhai, and Chen Hui
Reflected, transmitted and scattered light from tissues contains information about tissue properties. Hence, it has potential to be used for noninvasive characterization of biomedical tissues, which can lead to the development of techniques for the early detection of cancer. Time-resolved Monte Carlo model can predict Reflected, transmitted and scattered light from tissues contains information about tissue properties. Hence, it has potential to be used for noninvasive characterization of biomedical tissues, which can lead to the development of techniques for the early detection of cancer. Time-resolved Monte Carlo model can predict time dependent light distribution in tissues and has advantages of high precision and flexibility and can be used in many tissues. But there are some problems lie in Henyey-Greenstein (HG) phase function used in traditional Monte Carlo model. Thus, Mie phase function based on Mie theory is introduced. Comparison of time-resolved Monte Carlo simulations using several phase functions and experimental data shows that Mie phase function can predict diffuse reflectance of human tissue more real than HG phase function. Nevertheless, because Mie phase function is relative to scattering particle sizes of tissues and the sizes are different, the choice of scattering particle model is difficult when aiming at different particles distribution models..
Laser & Optoelectronics Progress
- Publication Date: Apr. 25, 2011
- Vol. 48, Issue 7, 71701 (2011)
Quantum Optics
Quantum Diffraction and Quantum Coherent Control During Multi-Photon Transition
Wang Peng
We theoretically explain how to achive the quantum coherent control of multi-photon transition by phase-modulated lightfield. The interaction between several types of shaped laser pulse and a two-level system is studied within the weak field regime. Quantum diffraction effect during the two-photon transition affected bWe theoretically explain how to achive the quantum coherent control of multi-photon transition by phase-modulated lightfield. The interaction between several types of shaped laser pulse and a two-level system is studied within the weak field regime. Quantum diffraction effect during the two-photon transition affected by a shaped laser pulse is studied. Under the perturbation theory, the analytical solutions of multi-photon transition probabilities are obtained. Based on these analytical expressions, we demonstrate that the quantum coherent control of multi-photon transition is affected by step-phase modulated laser and cosinusoidally phase modulated laser. It is shown that the elimination of transition probabilities exist in these two processes, and the two results have different probability elimination positions..
Laser & Optoelectronics Progress
- Publication Date: Jun. 01, 2011
- Vol. 48, Issue 7, 72701 (2011)
Reviews
Discussion on OFDM-PON and WDM-PON
Lin Rujian, Song Yingxiong, and Zhang Lin
Similarity and difference between orthogonal frequency division multiplexing passive optical network (OFDM-PON) and wavelength division multiplexing passive optical network (WDM-PON) are dicussed, indicating that WDM-PON is actually a kind of physical layer technique which can perform the functions of data transmissionSimilarity and difference between orthogonal frequency division multiplexing passive optical network (OFDM-PON) and wavelength division multiplexing passive optical network (WDM-PON) are dicussed, indicating that WDM-PON is actually a kind of physical layer technique which can perform the functions of data transmission system and network only by combining itself with some media access control (MAC) technique. In contrast, OFDM-PON is an optical access network working with the technique of orthogonal frequency division multiple accesses. Even its optical network units (ONUs) occupy different optical spectra, it is not a WDM-PON. Concept of OFDM-PON is clarified from two viewpoints: the optical beat interference (OBI) and MAC, to promote the development and standardization of OFDM-PON..
Laser & Optoelectronics Progress
- Publication Date: Jun. 20, 2011
- Vol. 48, Issue 7, 70601 (2011)
Research Progress of Sodium Guide Star Lasers
Lu Yanhua, Huang Yuanfang, Zhang Lei, Zhang Kai, Tang Chun, Wang Weimin, and Ma Yi
Sodium guide star lasers have a great application in the adaptive optics systems. The characteristic parameters and technique difficulties of the lasers are analyzed. According to the generation methods, the sodium guide star lasers can be divided into three types: dye lasers, solid lasers and fiber lasers. The developSodium guide star lasers have a great application in the adaptive optics systems. The characteristic parameters and technique difficulties of the lasers are analyzed. According to the generation methods, the sodium guide star lasers can be divided into three types: dye lasers, solid lasers and fiber lasers. The development history and the state of the art of them are expatiated. Dye lasers applied in engineering firstly have been washed out because of its big scale, low stability and dependability, and so on. Solid lasers include sum-frequency generation (SFG), stimulated Raman scattering (SRS) and optical parameter amplifier (OPA). SFG lasers are used mostly and developed into macro-micro pulse lasers, continuous single frequency lasers and continuous mode-locked lasers by scientists for different requirements. The commercial SFG lasers with 50 W average power have been produced recently. The fiber sodium guide star lasers as a novel type have been developed rapidly in recent years. Especially, the continuous single frequency sodium guide star lasers based on the Raman fiber amplifier and the second harmonious generation have exceeded 50 W average power..
Laser & Optoelectronics Progress
- Publication Date: Jun. 20, 2011
- Vol. 48, Issue 7, 71406 (2011)
Research Progress of Metamaterials for Terahertz Applications
Ding Pei, and Liang Erjun
Both terahertz (THz) electromagnetic wave and metamaterials are hot topics in electromagnetics research. Metamaterials operating in the THz range have achieved great successes in filling in the so-called “THz gap” due to its ability to control and manipulate electromagnetic waves. A comprehensive introduction to the prBoth terahertz (THz) electromagnetic wave and metamaterials are hot topics in electromagnetics research. Metamaterials operating in the THz range have achieved great successes in filling in the so-called “THz gap” due to its ability to control and manipulate electromagnetic waves. A comprehensive introduction to the progress of metamaterials at THz frequencies is given including the tuning strategies of electromagnetic response in metamaterials, metamaterials-based THz functional devices such as modulators/switchs, sensors/detectors, filters, polarimetric components, and absorbers etc., THz plasmonic metamaterials, nonmetallic structure to implement THz metamaterials as well as the advancements in fabricating THz metamaterials. It presents not only the metamaterials for THz applications but also their underlying mechanisms. Possible future directions in this field are also proposed..
Laser & Optoelectronics Progress
- Publication Date: May. 20, 2011
- Vol. 48, Issue 7, 71602 (2011)
Overview on Strapdown Inertial System Consisted by Optical Gyros
Zha Feng, Gao Jingdong, Xu Jiangning, and Hu Baiqing
The development of optical gyro and its application in strapdown inertial system are presented to summarize their tendencies and research directions. The progress of optical gyro technology in America and European and the domestic research state are reviewed after analyzing the operating principle and characteristic ofThe development of optical gyro and its application in strapdown inertial system are presented to summarize their tendencies and research directions. The progress of optical gyro technology in America and European and the domestic research state are reviewed after analyzing the operating principle and characteristic of optical gyro，and then the key technology of optical gyro is summarized. The development of strapdown inertial system consisting of optical gyro is presented after introducing the characteristic of strapdown inertial system and the applied trait of optical gyro. The technology adopted by the high precision system research in America is expounded, and then the research tendency of optical gyro strapdown inertial technology is summed up, which can offer references to high accuracy system research and manufacture..
Laser & Optoelectronics Progress
- Publication Date: May. 19, 2011
- Vol. 48, Issue 7, 72301 (2011)
Scattering
Total Intensity Property for Multiple Particles Side-Scattered Laser Radiation
Yuan Xingqi, Gao Wenying, and Zhang Mingjun
The properties of the total intensity of radiation side-scattered by the multiple particles when using linearly polarized incident light are studied experimentally. The scattering medium is the suspending liquid consisting of various concentrations of particles which are 0.065, 0.123, 0.220, 0.360, 0.494 or 1.240 μm inThe properties of the total intensity of radiation side-scattered by the multiple particles when using linearly polarized incident light are studied experimentally. The scattering medium is the suspending liquid consisting of various concentrations of particles which are 0.065, 0.123, 0.220, 0.360, 0.494 or 1.240 μm in diameter and mixed into filtered, distilled water. The experimental results show that the influence of various diameters of particles on the intensity of total side-scattered light is obvious in relation to scattering angles. The change of the intensity is greater when the diameters of the particles are reduced (1.240~0.123 μm). When the diameters reduce further (0.123~0.065 μm), the change has slowed down. The influence of the particle concentration and the depths on the total intensity is minute, not as obvious as the influence of the change of the diameters of the particles. And in the detected plane, the intensity distribution of each component of the side-scattered light is angular-symmetric..
Laser & Optoelectronics Progress
- Publication Date: May. 09, 2011
- Vol. 48, Issue 7, 72901 (2011)
Spectroscopy
Detection of Fecal Contaminants on Chicken Carcasses Using Segmented Principal Component Analysis and Band Ratio Algorithm
Zhao Jinhui, Yu Fang, Wu Ruimei, Liu Muhua, and Yao Mingyin
Using chicken carcasses as the research subject, fecal contaminants on chicken carcasses are detected by using hyperspectral imaging technology and combining segmented principal component analysis and band ratio algorithm. Firstly, hyperspectral images of chicken carcasses from 400 to 1000 nm are collected. Secondly, sUsing chicken carcasses as the research subject, fecal contaminants on chicken carcasses are detected by using hyperspectral imaging technology and combining segmented principal component analysis and band ratio algorithm. Firstly, hyperspectral images of chicken carcasses from 400 to 1000 nm are collected. Secondly, seven characteristic wavelengths (520.64，542.12，561.61，577.04，703.82，595.6 and 852.1 nm) are obtained by segmented principal component analysis, and the images obtained using 577.04/520.64 nm band ratio image added by 852.1/703.82 nm band ratio image are selected as the characteristic images of the detection of fecal contaminants on chicken carcasses. Lastly, the fecal contaminants on chicken carcasses are extracted using the threshold segmentation and mathematical morphology. The experimental results show that the accuracy rates of the detection for the fecal contaminants of ceca, colon and duodenum are 100%, 100% and 96% respectively, and the total accuracy rate of the detection is 93.3% using 60 samples of chicken carcasses..
Laser & Optoelectronics Progress
- Publication Date: Jun. 02, 2011
- Vol. 48, Issue 7, 73001 (2011)
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