Journals >Laser & Optoelectronics Progress
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2013
Volume: 50 Issue 10
30 Article(s)
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Fiber Optics and Optical Communications
Measurement of the Fibers′ Verdet Constant Based on an All Fiber-Optical Structure System
Li Yan, Jiang Man, Song Jingming, and Sun Yanfeng
In order to research the magnetic-optical characteristic, an all fiber-optical structure system is built to measure the fibers′ Verdet constant based on the Faraday effect. The system′s theoretical model is built with the Jones matrix. Through analysis and simulation, it is shown that the input fiber can influence the In order to research the magnetic-optical characteristic, an all fiber-optical structure system is built to measure the fibers′ Verdet constant based on the Faraday effect. The system′s theoretical model is built with the Jones matrix. Through analysis and simulation, it is shown that the input fiber can influence the measurement result, while the result is independent of the output fiber contrarily. Meanwhile the optimum length of the measured fiber is confirmed. Experimental system is built to measure the SMF-28e fiber′s Verdet constant. The measurement results prove that the Verdet constant of the SMF-28e fiber is 0.52±0.01 rad/(T·m), and the measurement results range from 0.52 rad/(T·m) to 0.56 rad/(T·m). Experiment is also taken under different driving voltages, and the result shows that the system has good linearity and feasibility, which also demonstrates the reliability and slability of the system..
Laser & Optoelectronics Progress
- Publication Date: Aug. 26, 2013
- Vol. 50, Issue 10, 100601 (2013)
Fiber Bragg Grating for Simultaneous Measurement of Strain and Temperature
Wang Zhenbao, Yang Pengling, Shao Bibo, Tao Mengmeng, Wu Yong, and Wu Junjie
In order to avoid cross-sensitive connection of temperature and strain in fiber grating sensing system, one dual-parameter sensor employing fiber Bragg grating (FBG) is investigated. Based on theories of temperature and strain testing using FBG, the operating principle of the dual-parameter sensor is described. The expIn order to avoid cross-sensitive connection of temperature and strain in fiber grating sensing system, one dual-parameter sensor employing fiber Bragg grating (FBG) is investigated. Based on theories of temperature and strain testing using FBG, the operating principle of the dual-parameter sensor is described. The experiment on the dual-parameter sensor is performed for linearity and sensitivity of temperature and strain, and measurement results combined effects of strain and temperature loading are described. Dynamic range and sensitivity of temperature FBG are about 0 ℃～100 ℃ and 12.2 pm/℃, for strain FBG about 1.79 pm/N. The experimental results show that this method can eliminate availably cross-sensitivity of temperature and strain for strain FBG sensor, and measure temperature and strain accurately and synchronously..
Laser & Optoelectronics Progress
- Publication Date: Aug. 19, 2013
- Vol. 50, Issue 10, 100602 (2013)
Polarization-Beat-Length-Based Achromatic Characteristics of Holey Birefringence Fiber with Hexagonal Lattice
Liu Zhen, Shi Zhidong, Yang Shaolin, Zhang Haiyan, Mao Yanping, and Xie Qingming
In view of the hexagonal lattice micro-structure optical fiber, the modal birefringence characteristics of holey fiber are simulated by the finite difference beam propagation method. The influence of the different cross-section structural parameters on modal birefringence is analyzed. Two groups of appropriate structurIn view of the hexagonal lattice micro-structure optical fiber, the modal birefringence characteristics of holey fiber are simulated by the finite difference beam propagation method. The influence of the different cross-section structural parameters on modal birefringence is analyzed. Two groups of appropriate structural parameters are obtained. The polarization beat lengths of these structures remain stable in a wide wavelength range，and thus better achromatic characteristics can be got. The working bandwidths of these structures reach 200 nm near the 1310 nm communication window and 260 nm near the 1550 nm communication window, respectively. The fibers are suitable for making wideband achromatic wave plates..
Laser & Optoelectronics Progress
- Publication Date: Sep. 02, 2013
- Vol. 50, Issue 10, 100603 (2013)
Performance Study of the Diversity Reception System Based on LDPC Codes
Liu Jialin, Hao Shiqi, Zhou Jianguo, and Wang Yong
In order to reduce the influence of atmospheric turbulence on the performance of atmospheric optical communication system, low-density parity-check (LDPC) codes combined with multiple-input multiple-output technologies is applied. Decoding initialization formulas of single-input multiple-output (SIMO) system are deriveIn order to reduce the influence of atmospheric turbulence on the performance of atmospheric optical communication system, low-density parity-check (LDPC) codes combined with multiple-input multiple-output technologies is applied. Decoding initialization formulas of single-input multiple-output (SIMO) system are derived in the forms of maximal ratio combining (MRC), equal gain combining (EGC) and selection combining, the system bit-error-rate (BER) performances are compared. The simulation results show that the atmospheric optical communication SIMO system of LDPC coding has better BER performance than that in SISO system; error performance of SIMO system differs with different combining schemes; the system in MRC has the lowest bit error rate followed by system in EGC with the same signal-to-noise ratio; with the increasing number of receiving antennas in a certain number of transmitting antennas, the BER will be decreased. So, it has some significance in the design of atmospheric optical communication system and theoretical research..
Laser & Optoelectronics Progress
- Publication Date: Aug. 19, 2013
- Vol. 50, Issue 10, 100604 (2013)
Research on the Ability of Fractional Fourier Transform to Reduce PAPR in CO-OFDM System
Liu Chang, Tong Zhengrong, Cao Ye, and Zhang Weihua
The high peak-average power ratio (PAPR) is a major factor affecting the performance of the optical orthogonal frequency division multiplexing (OOFDM) system. We put forward a novel coherent optical orthogonal frequency division multiplexing (CO-OFDM) system in which we use the fractional Fourier transform (FRFT) to reThe high peak-average power ratio (PAPR) is a major factor affecting the performance of the optical orthogonal frequency division multiplexing (OOFDM) system. We put forward a novel coherent optical orthogonal frequency division multiplexing (CO-OFDM) system in which we use the fractional Fourier transform (FRFT) to replace the traditional fast Fourier transform (FFT). Focus is put on the analysis of the principle that FRFT can reduce PAPR. The optical system simulation experiments show that the algorithm has obvious inhibitory effect on PAPR, but this inhibition cannot be improved infinitely: when the order is less than 0.001, the effect is no longer changed significantly..
Laser & Optoelectronics Progress
- Publication Date: Aug. 20, 2013
- Vol. 50, Issue 10, 100605 (2013)
Optical Trapping and Delivery of Chicken Red Blood Cells Using a Nanofiber
Li Ying, and Hu Yanjun
A method is presented to trap and deliver chicken red blood cells by using evanescent wave around an optical nanofiber. The nanofiber is fabricated by drawing a standard telecommunication single mode optical fiber through a flame-heated treatment. The nanofiber has a diameter of 700 nm, with one end connected to an 808A method is presented to trap and deliver chicken red blood cells by using evanescent wave around an optical nanofiber. The nanofiber is fabricated by drawing a standard telecommunication single mode optical fiber through a flame-heated treatment. The nanofiber has a diameter of 700 nm, with one end connected to an 808 nm laser source, leading to an extremely low insertion loss. The nanofiber is immersed in a solution of chicken red blood cells. The experimental result shows that, when the injected optical power is increased to 50 mW, the red blood cells near the nanofiber can be captured by optical gradient force and then delivered along the direction of light propagation due to the scattering force induced by the evanescent optical field. The calculated delivery velocity is 2.9 μm/s. By further experimental analysis, it is found that the velocity of red blood cells is linearly dependent on the input power. This technique could find some potential applications in trapping and manipulation of biological cells and virus..
Laser & Optoelectronics Progress
- Publication Date: Sep. 02, 2013
- Vol. 50, Issue 10, 100606 (2013)
Image Processing
Variable Step Detection of Product Surface Defect Based on Optimal Identification Interval
Xu Qing, Han Yueping, Yang Zhigang, and Sun Baohua
In order to achieve the detection of multiple regions in the product surface rapidly and accurately, we select variable step mechanism to obtain the circumferential image sequence of the products to be tested in the optimal recognition interval quickly so that some incomplete data could be utilized to realize the rapidIn order to achieve the detection of multiple regions in the product surface rapidly and accurately, we select variable step mechanism to obtain the circumferential image sequence of the products to be tested in the optimal recognition interval quickly so that some incomplete data could be utilized to realize the rapid detection of multiple areas in the limited orientation. First of all, we need to determine the optimal identification range of the area and the rotation step through relativity calculation and projection method. Secondly, the scale invariant feature transform (SIFT) algorithm and binary search method are selected to find the optimal location information of product in the standard image library. Finally, we distinguish there are some defects or not by relativity calculation. The experiment results demonstrate that the variable step size method based on optimal identification interval can save an average time of 6.37 s than the traditional full-circumferential fixed step method while ensuring the detection accuracy..
Laser & Optoelectronics Progress
- Publication Date: Sep. 02, 2013
- Vol. 50, Issue 10, 101001 (2013)
Imaging Systems
Design of V-Flexure Axial Adjusting Mechanism of Lithograph Projection Objective
Sun Zhen, and Gong Yan
An axial adjusting mechanism is designed to meet the requirement of long adjusting distance, high precision and compact structure in projection objective, based on triangular switching principle. V-flexure element is designed to achieve the switching and transmission of motion in adjusting mechanism. The parameters of An axial adjusting mechanism is designed to meet the requirement of long adjusting distance, high precision and compact structure in projection objective, based on triangular switching principle. V-flexure element is designed to achieve the switching and transmission of motion in adjusting mechanism. The parameters of V-flexure element are optimized to satisfy the requirement of adjusting distance, drive force, frequency and ratio of transmission. The influence of changing V-flexure element parameters on mechanism performance is analyzed by finite element analysis method. The result is that the adjusting distance is ±55 μm, the adjusting precision is better than ±10 nm and the frequency is more than 150 Hz. And then thermal deformation of lens is analyzed when the thermal load is 20 mW. The result is that the peak-to-valley (PV) value of the upper surface is 0.087 nm, and the root-mean-square (RMS) value is 0.013 nm. The simulation results show that the influence of axial adjusting mechanism on lens surface figure precision is small. Such an axial adjusting mechanism can satisty the requirement of lithograph projection objective..
Laser & Optoelectronics Progress
- Publication Date: Sep. 02, 2013
- Vol. 50, Issue 10, 101101 (2013)
Fuzzy Image Enhancement Based on Dual Chaotic Quantum Particle Swarm Algorithm
Li Dan, and Wang Hongtao
Aiming at the problem in fuzzy image enhancement, we proposed a dual chaotic quantum particle swarm optimization algorithm. Firstly, an additional contraction expansion factor is added to the quantum particle swarm to dynamically change the search boundary. Then the dual chiotic quantum mechanism system uses two differAiming at the problem in fuzzy image enhancement, we proposed a dual chaotic quantum particle swarm optimization algorithm. Firstly, an additional contraction expansion factor is added to the quantum particle swarm to dynamically change the search boundary. Then the dual chiotic quantum mechanism system uses two different chaotic mechanisms to independently search in the search space, and according to the distance between the optimal points obtained with two mechanisms, the search space is narrowed and the true optimal value can be got. Incomplete Beta function is adopted finally to astablish the relationsip between the dual chaotic quantum particle swarm optimization and fuzzy image enhancement recovery relationship. The experimental simulation shows a clear recovery effect of the proposed algorithm, and the overall visual effect of the image is fairly good. In comparison with other algorithms, the histogram shows that the proposed algorithm results in evenly distributed gray values and can significantly improve the signal-to-noise ratio..
Laser & Optoelectronics Progress
- Publication Date: Aug. 26, 2013
- Vol. 50, Issue 10, 101102 (2013)
Position-Pose Estimationfor Underwater Circular Objects Based on Monocular Laser Imaging
Lu Jing, Yang Kecheng, Xia Min, and Li Wei
Localization of underwater objects is essential for exploring the vast ocean resources. We present a monocular-vision-based method for estimating three-dimensional (3D) position-pose of underwater circular features. Using a single camera image, underwater circular features are extracted. After that, the image distortioLocalization of underwater objects is essential for exploring the vast ocean resources. We present a monocular-vision-based method for estimating three-dimensional (3D) position-pose of underwater circular features. Using a single camera image, underwater circular features are extracted. After that, the image distortion caused by the underwater environment is compensated, and both the orientation and position of the underwater circular features are estimated. Laboratory experiments demonstrate that the method is capable of estimating the 3D position-pose of a cylindrical object in clean water with the accuracy of orientation and position estimation of 1.33% and 4.37%, respectively. The stability of the method is also analyzed by moving and relocating the cylinder..
Laser & Optoelectronics Progress
- Publication Date: Aug. 26, 2013
- Vol. 50, Issue 10, 101103 (2013)
Instrumentation, Measurement and Metrology
Measurement of Laser-Generated Surface Wave Velocity of Non-Specular Tantalum Slice Based on Laser Interference
Ma Heli, Liu Shenggang, Tao Tianjiong, and Weng Jidong
Under the loading of nanosecond laser pulse, a surface wave ultrasonic velocity measurement technology for non-specular surface metal sample based on Michelson interferometer system is developed. In order to obtain characterful singal of surface wave, the convergent reflection signal light from non-specular surface of Under the loading of nanosecond laser pulse, a surface wave ultrasonic velocity measurement technology for non-specular surface metal sample based on Michelson interferometer system is developed. In order to obtain characterful singal of surface wave, the convergent reflection signal light from non-specular surface of tantalum slice interferes with attenuating reference light. In the interference intensity change history, distinct characteristic signal of surface wave can be inspected. Through the result of arrival time of different detection points and linear fitting method, surface wave of tantalum is successfully measured. A result of transverse wave velocity comparable to the reported one is obtained based on the measured surface wave ultrasonic velocity..
Laser & Optoelectronics Progress
- Publication Date: Sep. 02, 2013
- Vol. 50, Issue 10, 101201 (2013)
Lasers and Laser Optics
Heat Conduction Characteristics of Stainless Steel-Carbon Steel Laminated Sheet Bending Position
Ma Xupeng, Wang Xuyue, Xu Wenji, and Guo Dongming
Due to difference in the physical property between the base layer steel and the cover layer steel, laser bending area characteristics of the dissimilar metal laminated plates are different with the single sheet. Metallographic structures of laser bending areas in stainless steel-carbon steel laminated sheets under diffDue to difference in the physical property between the base layer steel and the cover layer steel, laser bending area characteristics of the dissimilar metal laminated plates are different with the single sheet. Metallographic structures of laser bending areas in stainless steel-carbon steel laminated sheets under different accumulative line energy are analysed in order to study heat conduction mode between the layers. By aking use of IPP image processing software to divide the heat-affected zone (HAZ), then energy transfer mode is analyzed. Heat transfer rate slows down because of thermal conductivity difference between the layers. Heat-affected areas present flat parabolic graded distribution in the mild carbon steel layer, and heat accumulation occurs on the lower surface. Bending angles of laminated sheets are determined by plastic deformation area and temperature gradient between the layers affected by heat conduction mode. Studies of heat conduction mode of stainless steel-carbon steel laminated sheets provide the basis of theory and experiment for better bending precision and quality..
Laser & Optoelectronics Progress
- Publication Date: Aug. 26, 2013
- Vol. 50, Issue 10, 101401 (2013)
Building of Simulation Environment for Sagnac Effect in Rotating Reference Frame
Zhang Xinxin, Jiang Hongbin, and Li Zhengbin
We propose a finite-difference time-domain algorithm in a rotating reference frame to facilitate systematic study of Sagnac effect in photonic devices. Through the design of software simulation on a cluster system platform, the relation between Sagnac phase shift and distance in different rotation systems and the stabiWe propose a finite-difference time-domain algorithm in a rotating reference frame to facilitate systematic study of Sagnac effect in photonic devices. Through the design of software simulation on a cluster system platform, the relation between Sagnac phase shift and distance in different rotation systems and the stability of finite-difference time-domain algorithm are verified. The experimental results show that the algorithm is capable of modeling the Sagnac effect effectively, and can be used for various devices with complicated geometry and material properties in the rotating reference performance evaluation system..
Laser & Optoelectronics Progress
- Publication Date: Sep. 02, 2013
- Vol. 50, Issue 10, 101402 (2013)
Medical Optics and Biotechnology
Regulating Sleep Clinical Research Based on Terahertz Needle Irradiation Acupoints
Liu Yubo, Wang Wanzhi, Jiang Yongtao, Cui Han, Li Kai, Yu Haibo, Li Zhifeng, and Jin Lei
As we all know, in the family of electromagnetic spectrum, γ-ray, X-ray, ultraviolet, visible, infrared and microwave have all been playing an important role in the field of medical treatment. However, terahertz (THz) radiation which is between microwave and infrared is still in the early stages of development. THz wavAs we all know, in the family of electromagnetic spectrum, γ-ray, X-ray, ultraviolet, visible, infrared and microwave have all been playing an important role in the field of medical treatment. However, terahertz (THz) radiation which is between microwave and infrared is still in the early stages of development. THz wave with specific wavelength is focused into a line, called THz needle. For sleep therapy research, the THz needle regulating sleep clinical efficacy is explored. After clinical experiment, it is found that THz waves can effectively improve the quality of sleep. For further study of the mechanism of the interaction of THz radiation with the human body, we specifically observe some interesting details of clinical trials. In the photoplethysmography (PPG) signal after irradiation THz wave, a second small peak appears, and the patient′s serum potassium concentration increases. This study not only provides an effective, non-invasive physical method for sleep therapy, but also offers THz technology itself new research materials..
Laser & Optoelectronics Progress
- Publication Date: Sep. 02, 2013
- Vol. 50, Issue 10, 101701 (2013)
Research on the Technology of Parallel Laser Confocal Microscopy Detection Based on Digital Micromirror Device
Tu Long, Yu Jin, Fan Zhongwei, Qiu Jisi, Zhao Tianzhuo, Wang Zhihao, Wu Quan, Ge Wenqi, Guo Guangyan, and Wang Haocheng
In order to measure workpiece′s micro-nano three-dimensional topography, a parallel confocal microscopy detection system based on digital micromirror device(DMD) is set up. Firstly, the Fraunhofer diffraction model of DMD is studied. Secondly, the parallel scanning model of 2×2 pixel unit and T=3 is realized by thIn order to measure workpiece′s micro-nano three-dimensional topography, a parallel confocal microscopy detection system based on digital micromirror device(DMD) is set up. Firstly, the Fraunhofer diffraction model of DMD is studied. Secondly, the parallel scanning model of 2×2 pixel unit and T=3 is realized by the use of DMD. Then the three-dimensional image reconstruction algorithm and laser speckle homogenization is analyzed. Finally, the measuring system makes three-dimensional measurements for coated plate, WSZ position sensitive anode detector and screw respectively. The experimental results show that the three-dimensional reconstruction image is obtained under the condition that the stepping motor moves 10 nm per step. This parallel confocal microscopy system greatly improves the three-dimensional testing speed and can satisfactorily meet the general industrial testing requirement. It provides a new method of research and application for parallel confocal detection technology..
Laser & Optoelectronics Progress
- Publication Date: Aug. 27, 2013
- Vol. 50, Issue 10, 101702 (2013)
Research on Genistein-Encapsulated Nanoparticles Based on Dynamic Light Scattering Technique
Lou Benzhuo
Genistein possesses antibacterial and antioxidant effects. Thermal processing may lead to a decrease of above biological activities of genistein through oxidative degradation. The genistein-encapsulated nanoparticles are prepared by using the techniques of microemulsion and complex coacervation and their surface potentGenistein possesses antibacterial and antioxidant effects. Thermal processing may lead to a decrease of above biological activities of genistein through oxidative degradation. The genistein-encapsulated nanoparticles are prepared by using the techniques of microemulsion and complex coacervation and their surface potential and particle size distribution are analyzed by using dynamic light scattering method. The analysis of Zeta-potential shows that the negative potential difference of surface of nanocapsule significantly increases with the colloid layers increasing and this indicates that the addition of locust bean gum and Arabic gum can increase the negative charges across the nanocapsule surface. The study of particle size distribution suggests that the total average radius of genistein-encapsulated nanoparticles consisted of two particle groups is about 43.7 nm, corresponding to the dispersed single nanocapsule and aggregated nanocapsule, which have the average particle radii of 5.9 nm (72.3%) and 139.9 nm (27.7%). In addition, the total average diameter of nanocapsule is 7.4~10.0 nm at different pH and is not significantly different, but aggregated nanocapsule is found at pH is 6.8 and 7.4..
Laser & Optoelectronics Progress
- Publication Date: Aug. 07, 2013
- Vol. 50, Issue 10, 101703 (2013)
Optical Design and Fabrication
Optimization Design Method for Laser Beam Shaping System Based on Optics Non-Imaging
Liu Lihong, Liu Hua, Sun Qiang, Liu Ying, Jing Lei, and Xin Di
A new design method of diffractive microlens array for laser beam uniformity adopting optimization procedure in Zemax is proposed. The custom optimization function in Macro language is created by means of energy mapping in non-imaging optics. A microlens array and a condensing spherical lens are used as the homogenizatA new design method of diffractive microlens array for laser beam uniformity adopting optimization procedure in Zemax is proposed. The custom optimization function in Macro language is created by means of energy mapping in non-imaging optics. A microlens array and a condensing spherical lens are used as the homogenization optical components in the system. The aspheric surface of the lens unit of the microlens array is automatically optimized in sequential mode of Zemax software, and a 6 mm×6 mm square spot with the irradiance uniformity greater than 90% and the energy efficiency of 83% on the target surface is realized. The design results are verified by TracePro simulation program. This method is valid and convenient in the system design of the microlens array for laser beam uniformity, without the need for the complex calculation and the repeating adjustment of the system parameters in the traditional method..
Laser & Optoelectronics Progress
- Publication Date: Aug. 26, 2013
- Vol. 50, Issue 10, 102201 (2013)
Optical Lens Design with Short-Focus and Ultra-Wide FOV
Zhang Jiyan, Huang Yuanqing, Xiong Feibing, Meng Xianguo, and Lin Haifeng
The optical design of a short focus and ultra-wide field of view (FOV) lens used for monitoring is discussed. The optical system uses inverted telephoto optical structure. The equidistant projection imaging mode is adopted according to the design requirements. The Zemax software is adopted to optimize and design the syThe optical design of a short focus and ultra-wide field of view (FOV) lens used for monitoring is discussed. The optical system uses inverted telephoto optical structure. The equidistant projection imaging mode is adopted according to the design requirements. The Zemax software is adopted to optimize and design the system. The marginal FOV illumination and off axis aberration are solved. The structure features of the lens are discussed and the aberration curves and medulation transfer function (MTF) curves are showed. The lens has a structure of 7 groups and 10 pieces. The marginal FOV and relative aperture of the final design is up to 175° and 1/1.8 respectively, and inverted telephoto ratio is 2.4. Using 1/3 ″CCD imaging device, full FOV MTF value reached 0.5 at 100 lp/mm. Optical system has compact structure, excellent image quality..
Laser & Optoelectronics Progress
- Publication Date: Aug. 07, 2013
- Vol. 50, Issue 10, 102202 (2013)
Design of Solar Blind Ultraviolet Warning Optical System
Song Shanshan, Lin Lina, and Wang Wensheng
Ultraviolet (UV) warning technology has been widely applied in missile approach warning. According to the user requirement, a solar blind UV warning optical system is designed for the wavelength range from 240~280 nm. In order to improve the luminous flux, expand the search scope and simplify system structure, an aspheUltraviolet (UV) warning technology has been widely applied in missile approach warning. According to the user requirement, a solar blind UV warning optical system is designed for the wavelength range from 240~280 nm. In order to improve the luminous flux, expand the search scope and simplify system structure, an aspherical surface and binary optical elements are used. The initial optical data are based on the existing design that has a relative aperture of 14, the field of view of 30°, and consists of 6 pieces of lenses. As a result, the optical system is reduced to five pieces of lenses, the field of view is extended to 40°, and the relative aperture is increased to 13. PIXIS 2048BUV UV CCD whose pixel size is 13.5 μm×13.5 μm is applied as the detector. Image quality evaluation results show that this solar blind UV warning optical system is of high energy concentration, and the spot size is smaller than the pixel size of CCD, which satisfy the application requirements. The system has the advantages of large field of view and large relative aperture, and its technical characteristics are superior to the existing solar blind UV warning optical systems..
Laser & Optoelectronics Progress
- Publication Date: Sep. 02, 2013
- Vol. 50, Issue 10, 102203 (2013)
Design and Simulation of the Optical System of LED Solar Simulator
Sun Jiangang, Li Guohua, Zhu Kongshuo, Zhao Jiexin, and Ma Xiaoguang
An optical system of LED solar simulator for photovoltaic performance test is designed by using LED source. A method of employing LEDs with different peak wavelengths as light source to build a solar spectrum is introduced. By taking use of the characteristics of the LEDs, a concentric transmission collimating system iAn optical system of LED solar simulator for photovoltaic performance test is designed by using LED source. A method of employing LEDs with different peak wavelengths as light source to build a solar spectrum is introduced. By taking use of the characteristics of the LEDs, a concentric transmission collimating system is used, including high power LEDs, collimating system, Fresnel lens, optical integrator and aperture. The free-form surface collimating system with the total internal reflection of free-form surface lens and symmetrical lens array structure in optical integrator is adopted. The results demonstrated by optical simulation software of TracePro show that in the effective radiation circle area within 220 mm diameter, the non-uniformity is 3.8% and the collimation angle is 3.2°..
Laser & Optoelectronics Progress
- Publication Date: Sep. 02, 2013
- Vol. 50, Issue 10, 102204 (2013)
Remote Sensing and Sensors
Algorithm of Phase Error Compensation for Inverse Synthetic Aperture Ladar
Ruan Hang, Wu Yanhong, Ye Wei, and Jia Xin
Since the transmitted signal of inverse synthetic aperture ladar (ISAL) has a very short wavelength, even the weak vibration of the target or the platform will seriously corrupt the ISAL image. In addition, existence of random phase error of the initial phases of the transmitted pulses of ISAL will greatly degrade ISALSince the transmitted signal of inverse synthetic aperture ladar (ISAL) has a very short wavelength, even the weak vibration of the target or the platform will seriously corrupt the ISAL image. In addition, existence of random phase error of the initial phases of the transmitted pulses of ISAL will greatly degrade ISAL images due to the limitation of the laser modulation technology, which also results in a defocused image of ISAL. The phase gradient autofocus (PGA) algorithm fails to compensate the phase errors induced by a high-frequency vibration; meanwhile, the spatial correlation algorithm (SCA) has a limited function on compensating the phase errors because of the relative rotation between the target and ISAL. Combining PGA and SCA, a new phase error compensation algorithm, which can be named PGA-SCA, is proposed. The effect of the relative rotation is eliminated by a circular shifting and windowing operation. Simulation results show that, the proposed algorithm is effective in correcting the phase errors and capable to generate a well-focused ISAL image..
Laser & Optoelectronics Progress
- Publication Date: Aug. 20, 2013
- Vol. 50, Issue 10, 102801 (2013)
SPR Technology in Detecting the Imaginary Part of Refractive Index of Absorptive Medium
Zhang Yingying
In this paper, the surface plasmon resonance (SPR) technology for measuring the absorptive sample′s imaginary part of the refractive index is studied via numerical simulations. By using the Fresnel equation, intensity, phase, and angle modulations are analyzed. The results show that, the angle interrogation has the higIn this paper, the surface plasmon resonance (SPR) technology for measuring the absorptive sample′s imaginary part of the refractive index is studied via numerical simulations. By using the Fresnel equation, intensity, phase, and angle modulations are analyzed. The results show that, the angle interrogation has the highest resolution (1×10-6 RIU) and the widest linear measurement range. So the angular modulation is a good choice for measuring the absorptive sample′s imaginary part of the refractive index..
Laser & Optoelectronics Progress
- Publication Date: Aug. 07, 2013
- Vol. 50, Issue 10, 102802 (2013)
Reviews
Research Progress of 980 nm Fiber Laser
Li Pingxue, Yang Chun, Yao Yifei, Chi Junjie, Zhao Ziqiang, Zhang Guangju, and Hu Haowei
Yb-doped fiber laser systems operating around 980 nm have great potential to become new pump source for Er-doped and Yb-doped fiber lasers. Moreover, these sources can get blue green lasers with frequency conversion. Two important points to obtain 980 nm fiber lasers including overcoming four-level regime oscillation aYb-doped fiber laser systems operating around 980 nm have great potential to become new pump source for Er-doped and Yb-doped fiber lasers. Moreover, these sources can get blue green lasers with frequency conversion. Two important points to obtain 980 nm fiber lasers including overcoming four-level regime oscillation and re-absorption are discussed. Current research status of fiber lasers operating around 980 nm with different operation modes including continuous wave, Q-switch and mode-locking is introduced. At last, future applications and developments are also presented..
Laser & Optoelectronics Progress
- Publication Date: Sep. 02, 2013
- Vol. 50, Issue 10, 100001 (2013)
Survey on Linear Structured Light Stripe Center Extraction
Li Yingying, Zhang Zhiyi, and Yuan Lin
In the linear structured light three-dimensional measurement system based on triangulation, how to quickly and accurately extract light strip center from an image is pivotal to real-time and precise measurement. Firstly, the factors influencing light strip center extraction are described, such as linear structured lighIn the linear structured light three-dimensional measurement system based on triangulation, how to quickly and accurately extract light strip center from an image is pivotal to real-time and precise measurement. Firstly, the factors influencing light strip center extraction are described, such as linear structured light sources, environmental noise and surface reflectance properties of the measured object. Then the existing methods, including specialized light image de-noising and threshold segmentation technologies, traditional and improved light strip center extraction algorithms, are summarized. The principle and key technology of these algorithms are analyzed. Finally, some advices aiming at problems appearing in the existing methods are given, and it is pointed out that the developing monocular laser systems which can handle with high pixels image and can be used in outdoor light and complicated natural environment are the development trend in the future..
Laser & Optoelectronics Progress
- Publication Date: Sep. 02, 2013
- Vol. 50, Issue 10, 100002 (2013)
Progress on Single Mode Vertical Cavity Surface Emitting Lasers
Hao Yongqin, Yan Changling, Ma Xiaohui, Liu Guojun, Feng Yuan, Li Te, Wei Zhipeng, and Jiang Huilin
The main advantages of vertical cavity surface emitting lasers (VCSELs) are low threshold current, a circular output-beam profile, high modulation bandwidth, single-longitudinal-mode operation and easy two-dimensional integration with high density. A single transverse mode VCSEL is considered to be a desired light sourThe main advantages of vertical cavity surface emitting lasers (VCSELs) are low threshold current, a circular output-beam profile, high modulation bandwidth, single-longitudinal-mode operation and easy two-dimensional integration with high density. A single transverse mode VCSEL is considered to be a desired light source for optical communication, high-speed local-area networks, and optical interconnect. After analysing structural and modal features of a VCSEL, important progress of single transverse mode VCSELs is presented and discussed. Finally, prospect and problems of future research are presented..
Laser & Optoelectronics Progress
- Publication Date: Sep. 02, 2013
- Vol. 50, Issue 10, 100003 (2013)
Development Status of Range-Gated Laser Active Imaging Technology Under Atmospheric Condition
Guo Huichao, Sun Huayan, and Fan Youchen
The range-gated laser active imaging technology is a research focus because it has many advantages such as long range, independent of environment illumination, suppressing the backscattering, and capable of three-dimensional (3D) imaging. We introduce the principle of the gated-viewing technology, and analyze the repreThe range-gated laser active imaging technology is a research focus because it has many advantages such as long range, independent of environment illumination, suppressing the backscattering, and capable of three-dimensional (3D) imaging. We introduce the principle of the gated-viewing technology, and analyze the representative researches in China and abroad on application the technology of long-range surveillance and 3D imaging, including typical systems, technical characteristics and application status. Finally, several future research trends of the range-gated viewing technology are given..
Laser & Optoelectronics Progress
- Publication Date: Aug. 26, 2013
- Vol. 50, Issue 10, 100004 (2013)
New Research Progress on Distributed Optical Fiber Sensor Technique Based on BOTDA
Peng Yingcheng, Qian Hai, Lu Hui, and Guo Xian
Brillouin optical time domain analysis (BOTDA) is presently the mainstream in distributed optical fiber measuring techniques. Research progress and technical methods are introduced. The characteristics and the main technological limits of BOTDA are stated in this paper. Two novel techniques, pulse-prepump-BOTDA (PPP-BOBrillouin optical time domain analysis (BOTDA) is presently the mainstream in distributed optical fiber measuring techniques. Research progress and technical methods are introduced. The characteristics and the main technological limits of BOTDA are stated in this paper. Two novel techniques, pulse-prepump-BOTDA (PPP-BOTDA) and differential pulse-width pair-BOTDA (DPP-BOTDA), with which special resolution, measuring precision and signal-to-noise ratio (SNR) can be improved, are introduced. New techniques that employ the characteristics of polarization-maintaining fiber (PMF) and photonic crystal fiber (PCF) to measure temperature and strain simultaneously are introduced..
Laser & Optoelectronics Progress
- Publication Date: Sep. 02, 2013
- Vol. 50, Issue 10, 100005 (2013)
Light Extraction Enhancement of Photonic Crystal LEDs with Complex Technology
Shen Xiaoxia, Dong Guoyan, Ren Yazhou, Wang Xinzhong, and Zhou Zhiwen
Several methods to improve the light extraction efficiency of GaN light emitting diode (LED) are introduced. These methods include fabricating a GaN LED with photonic crystal and other structures, such as microcavity, omni-directional reflector, patterned sapphire substrate, AlGaN confining layer, and embedded photonicSeveral methods to improve the light extraction efficiency of GaN light emitting diode (LED) are introduced. These methods include fabricating a GaN LED with photonic crystal and other structures, such as microcavity, omni-directional reflector, patterned sapphire substrate, AlGaN confining layer, and embedded photonic crystals. These structures would change the optical design of LEDs and modulate the distribution of guide modes in LEDs to improve the light extraction efficiency. From experiment demonstration and theoretical analysis of five specially designed LEDs, it is found that the characteristics of LED light emission are modulated and the LED light emission intensity is enhanced considerably compared with conventional LEDs..
Laser & Optoelectronics Progress
- Publication Date: Aug. 07, 2013
- Vol. 50, Issue 10, 100006 (2013)
Spectroscopy
Dressed Selective Reflection Spectra of a Transparent-Dielectric/Metal (Ferroelectric)-Layer/Confined-Atoms System
Li Li, Zhao Xiaoxia, Li Yuanyuan, and Zhang Yanpeng
Dressed selective reflection (DSR) spectra in a two-interface system of transparent-dielectric/metal (ferroelectric)-layer/confined-atoms are investigated . Three different films of KTa0.65Nb0.35O3, Ag and Fe are considered in our discussion. Symmetry dispersion DSR lines are shown for L/λ=0.25 and 0.75, where L is theDressed selective reflection (DSR) spectra in a two-interface system of transparent-dielectric/metal (ferroelectric)-layer/confined-atoms are investigated . Three different films of KTa0.65Nb0.35O3, Ag and Fe are considered in our discussion. Symmetry dispersion DSR lines are shown for L/λ=0.25 and 0.75, where L is the thickness of the atomic vapor, and λ the wavelength of the probe field. This symmetry decreases with a combination of absorption and dispersion for L/λ=0.9, however, DSR lines almost disappear for L/λ=1. There is a slight decrease of the DSR amplitude when the thickness of KTa0.65Nb0.35O3 layer decreases. However, the DSR amplitude can be largely enhanced for metal layers, and this enhancement is the most manifest case when an ideal metal Ag layer is used. Electromagnetically induced reflection with high resolution (up to about 10 MHz) can be achieved due to the quantum interference of two dressed states and alternating current (ac) Strark splitting created by a coupling field. This high-resolution electromagnetically induced reflection dip can probably be used in the measurement of the optical parameters of surface layers, as well as the detection of optoelectronic devices in integrated optics..
Laser & Optoelectronics Progress
- Publication Date: Aug. 26, 2013
- Vol. 50, Issue 10, 103001 (2013)
Experimental Study of Super-bBoadband Terahertz Coherent Detection with Air Plasma
He Jun, Mu Kaijun, Yang Hua, Hou Deting, Ma Shengcan, and Shi Xiaoyan
Super-broadband spectrum detection technology has an important significance for high-resolution terahertz (THz) absorption spectrum measurements, as well as scientific research and application of terahertz development. We use air plasma as the detection medium and successfully detect super-broadband THz spectra. The deSuper-broadband spectrum detection technology has an important significance for high-resolution terahertz (THz) absorption spectrum measurements, as well as scientific research and application of terahertz development. We use air plasma as the detection medium and successfully detect super-broadband THz spectra. The detection mechanism is investigated by experiments. We use the system to measure two kinds of explosives′ super-broadband absorption spectra. The results indicate that THz spectra widths increase with pump power or bias, and super-broadband absorption spectra match well with Fourier transform infrared (FTIR) pectra in low frequency area..
Laser & Optoelectronics Progress
- Publication Date: Sep. 02, 2013
- Vol. 50, Issue 10, 103002 (2013)
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