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2016
Volume: 53 Issue 8
37 Article(s)
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Atmospheric Optics and Oceanic Optics
Experimental Analysis of Beam Wander and Beam Spreading under Different Surfaces
Wang Hongxing, Song Bo, Wu Xiaojun, and Liu Min
Beam wander and beam spreading are two important effects for beam propagation in the atmospheric turbulence. Collimated Gaussian beam propagation experiments by means of CCD technique are conducted under the sea, the beach and the road surface environments in the region of Yantai. Beam wander, beam spreading and refracBeam wander and beam spreading are two important effects for beam propagation in the atmospheric turbulence. Collimated Gaussian beam propagation experiments by means of CCD technique are conducted under the sea, the beach and the road surface environments in the region of Yantai. Beam wander, beam spreading and refractive index structure parameters are measured, and the characteristics of beam wander and beam spreading are analyzed based on measured data. The results show that the fluctuating amplitude of beam spreading and beam wander is the largest on the sea when the refractive index structure parameter changes a little. The fluctuating amplitude of them is 0~1.5 cm and 0~0.6 cm, respectively. The relative error of beam spreading on the beach surface is the least, and it is less than 10%. The refractive index structure parameter on the road can be one order larger than those on the sea and on the beach. The variation tendency of beam spreading and beam wander is the same as that of refractive index structure parameter..
Laser & Optoelectronics Progress
- Publication Date: Jul. 29, 2016
- Vol. 53, Issue 8, 80101 (2016)
Analysis of Basic Parameters of Adaptive Optics Based on Grating Wavefront Curvature Sensor
Zhang Yongtao, Li Xiaoyang, Chen Bo, Yang Xu, and Sun Tianqi
For the real-time wavefront reconstruction method with the eigenfunctions of Laplacian in adaptive optics based on grating wavefront curvature sensor, three basic parameters including the selected light spot size and the position deviation on photoelectric detector, and the influence of the number of eigenfunctions modFor the real-time wavefront reconstruction method with the eigenfunctions of Laplacian in adaptive optics based on grating wavefront curvature sensor, three basic parameters including the selected light spot size and the position deviation on photoelectric detector, and the influence of the number of eigenfunctions modes on the precision of wavefront reconstruction are analyzed. The results show that the selected light spot size on the photoelectric detector has an obvious effect on the wavefront reconstruction accuracy, which can be obtained by the ring energy ratio. Because of other diffraction orders light on photoelectric detector, the position deviations of the light spot induce not only the wavefront tilt error but also other wavefront errors. The mode coupling due to the limited resolution can significantly affect the accuracy of the wavefront reconstruction when using too many modes, and the optimal mode number can be estimated via the correlation coefficient between modes..
Laser & Optoelectronics Progress
- Publication Date: Jul. 12, 2016
- Vol. 53, Issue 8, 80103 (2016)
Water Body Information Extraction Based on Operational Land Imager Imagery and Principal Component Analysis: A Case Study of Poyang Lake Region
Zhou Xiaoli, Guo Jiawei, and Liu Kunming
The use of satellite images to quickly and accurately extract the distribution of the earth′s surface water body has been an important research topic all the time, which has important significance for water disaster monitoring, water resource utilization, etc. The operational land imager (OLI) remote sensing imagery isThe use of satellite images to quickly and accurately extract the distribution of the earth′s surface water body has been an important research topic all the time, which has important significance for water disaster monitoring, water resource utilization, etc. The operational land imager (OLI) remote sensing imagery is used to obtain the surface reflectance values of the images by radiometric calibration and atmospheric correction. Then principal components water index (PCWI) is constructed by analyzing the construction method of the typical water index and the principal component space features of ground objects. Taking Poyang Lake as the research area, two different time OLI images are selected during the dry season to extract water body information by using PCWI. The overall accuracy is 95.92% and 95.52% respectively. Compared with the water body extraction effects of other existing five typical water index, the overall effect of water extraction based on PCWI for the two different time OLI images is the best. In conclusion, PCWI of water extraction is feasible and effective..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2016
- Vol. 53, Issue 8, 80104 (2016)
Detectors
Absorption Enhancement of Crystalline Silicon Thin Film Solar Cell Using Nano Binary Silver Grating
Lu Huidong, Tie Shengnian, and Liu Jie
In order to enhance light trapping in the crystalline silicon（c-Si）thin film solar cell, a cell structure that can significantly enhance light absorption is presented, which is composed of antireflection coatings, active layer, and back mirrors. Based on the basic principle of effective refractive index modulation and In order to enhance light trapping in the crystalline silicon（c-Si）thin film solar cell, a cell structure that can significantly enhance light absorption is presented, which is composed of antireflection coatings, active layer, and back mirrors. Based on the basic principle of effective refractive index modulation and the rigorous coupled wave theory, optical properties of different layers are discussed through the numerical calculation and simulation, including the transmissivity of antireflection coatings, the reflectivity of back mirror, and the absorptance of the optimized c-Si thin film solar cell. Under the radiation of AM1.5G (solar spectrum including diffused reflection received at the earth surface with a 48° angle incidence) spectrum and for the c-Si thin film solar cell with 20 μm thick active layer, incident wave with TM polarization, and incident angle less than 75°, the integrated absorptance reaches 85.7%, 49%, and 14%, respectively when the wavelength ranging from 400 to 850 nm, 850 to 1000 nm, and 1000 to 1100 nm. It can effectively compensate for the shortage of near infrared absorptance in the crystalline silicon thin film solar cell..
Laser & Optoelectronics Progress
- Publication Date: Jul. 29, 2016
- Vol. 53, Issue 8, 80401 (2016)
Fiber Optics and Optical Communications
Comparison Between Interferometric and Resonant Integrated Optic Gyroscopes
Yang Tianshu, Fei Yao, Li Zhaofeng, Liu Wen, Li Yan, Wang Xiaodong, and Yang Fuhua
This paper compares the interferometric integrated optic gyro (IIOG) and the resonant integrated optic gyro (RIOG). In order to make them comparable, the two kinds of gyros use devices with the same parameters, similar bias modulation methods and planar waveguides with the same footprint and the same propagation loss fThis paper compares the interferometric integrated optic gyro (IIOG) and the resonant integrated optic gyro (RIOG). In order to make them comparable, the two kinds of gyros use devices with the same parameters, similar bias modulation methods and planar waveguides with the same footprint and the same propagation loss for Sagnac effect sensing. Firstly, the exact expressions of the shot-noise-limited sensitivities of the IIOG using the square wave modulation and the RIOG using the triangular wave modulation are derived. Then the optimized shot-noise-limited sensitivities of the two kinds of gyros are calculated by optimizing the waveguides parameters. Results show that as the propagation loss of the planar waveguide decreases, the IIOG has better shot-noise-limited sensitivity than the RIOG. As the manufacturing technology of the ultra-low loss planar waveguide develops, the IIOG has much potential in sensitivity improving..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2016
- Vol. 53, Issue 8, 80601 (2016)
On-Line Temperature Monitoring in Railway Existing Fiber Cable Based on Brillouin Optical Time-Domain Reflectometry
Cao Yulong, Ye Qing, and Cai Haiwen
The Brillouin frequency shift is linearly related to the temperature change along the single-mode fiber. Based on the linear temperature sensitivity, the Brillouin optical time-domain reflectometry (BOTDR), as one of the distributed optical fiber Brillouin sensing system, can realize detection of temperature distributiThe Brillouin frequency shift is linearly related to the temperature change along the single-mode fiber. Based on the linear temperature sensitivity, the Brillouin optical time-domain reflectometry (BOTDR), as one of the distributed optical fiber Brillouin sensing system, can realize detection of temperature distribution along the existing fiber cable in the railway communication system. Three kinds of cables with different cablecasting styles, including cement cladding, iron piping and directly buried laying, are positioned and tested, and temperature change curves are obtained. Temperature variation for the three kinds of fibers is 10, 8, and 6 ℃, respectively, and the temperature rising rate is 10, 8, and 1 ℃/h, respectively. The experimental results show that the BOTDR sensing system can reflect the trend and the rate of temperature change, and can be used for on-line temperature monitoring on railway communication fiber cables..
Laser & Optoelectronics Progress
- Publication Date: Jul. 26, 2016
- Vol. 53, Issue 8, 80602 (2016)
Study on Broadening Characteristics of Partially Coherent Gaussian Pulse in Atmospheric Turbulence
Ke Xizheng, and Zhang Huanjie
Pulse broadening has a great influence on the increase of inter symbol interference of wireless optical communication system. Based on the generalized Huygens-Fresnel principle and the modified von Karman spectrum model, a detailed numerical analysis on pulse broadening of the partially coherent Gaussian Schell model pPulse broadening has a great influence on the increase of inter symbol interference of wireless optical communication system. Based on the generalized Huygens-Fresnel principle and the modified von Karman spectrum model, a detailed numerical analysis on pulse broadening of the partially coherent Gaussian Schell model pulse (GSMP) beam propagation in atmospheric turbulence is discussed. The analytic expressions of the mean intensity and the pulse broadening of the partially coherent GSMP beam propagating in atmospheric turbulence in frequency domain and time domain are derived. The results indicate that the partially coherent GSMP beam is less affected by turbulence than the fully coherent GSMP beam, and that the smaller the partially coherent beam waist radius is, the more serious the beam is affected by turbulence. In the frequency domain, under the same propagation condition, the stronger the turbulence and the bigger the outer scale is, the more obvious the GSMP beams broadening effect is. In the time domain, with the increase of the initial pulse width, the relative pulse width at the receiver ending decreases rapidly. Within 40 femtoseconds, the relative pulse width is very obvious. With more than 40 femtoseconds, there is no significant difference between the pulse width on the receiver and the initial pulse width..
Laser & Optoelectronics Progress
- Publication Date: Jul. 12, 2016
- Vol. 53, Issue 8, 80603 (2016)
High Precision Temperature Measurement Based on π-Phase-Shifted Fiber Bragg Grating
Yu Bo, Jing Mingyong, Hu Jianyong, Zhang Guofeng, Xiao Liantuan, and Jia Suotang
The photothermal effect can induce the frequency fluctuations of π-phase-shifted fiber Bragg grating (PSFBG), so the incident laser is attenuated to the single photon level in order to eliminate the photothermal effect. The intensity of the incident single photon is modulated, and then the transistor-transistor logics The photothermal effect can induce the frequency fluctuations of π-phase-shifted fiber Bragg grating (PSFBG), so the incident laser is attenuated to the single photon level in order to eliminate the photothermal effect. The intensity of the incident single photon is modulated, and then the transistor-transistor logics (TTL) signal pulses of photoelectric conversion are directly demodulated with the lock-in amplifier. Thereby the environmental temperature is measured by using the PSFBG. The precision for temperature measurement is up to 0.14 ℃..
Laser & Optoelectronics Progress
- Publication Date: Jul. 21, 2016
- Vol. 53, Issue 8, 80604 (2016)
Image Processing
Super-Resolution Optical Fluctuation Imaging Algorithm Based on Spatial Gaussian Filter
Li Rui, Qu Huiming, Zhang Yunhai, and Jiang Shan
In order to achieve real-time imaging with superresolution optical fluctuation imaging (SOFI), a novel SOFI algorithm combined with image filtering is proposed. Muti-frame images should be filtering processing, and the super-resolution images with high signal-noise ratio are obtained utilizing SOFI algorithm depending In order to achieve real-time imaging with superresolution optical fluctuation imaging (SOFI), a novel SOFI algorithm combined with image filtering is proposed. Muti-frame images should be filtering processing, and the super-resolution images with high signal-noise ratio are obtained utilizing SOFI algorithm depending on temporal self correlations of fluorescent particles in muti-frame images. The result show that the SOFI algorithm based on spatial Gaussian filter can get a high signal-noise ratio super-resolution image from the low signal-noise ratio image sequences, and the calculating speed can be accelerated to 2.3 times, comparing different filters, weighing denoising effect and image resolution..
Laser & Optoelectronics Progress
- Publication Date: Jul. 27, 2016
- Vol. 53, Issue 8, 81001 (2016)
Medical Image Registration Algorithm Based on Polynomial Deterministic Matrix and SIFT Transform
Yang Sa, Xia Minghua, and Zheng Zhihuo
Given that random measurement matrix has defect in hardware realization, a scale-invariant feature transform (SIFT) based on polynomial deterministic matrix algorithm is proposed combining with the sparse projection of compressive sensing theory. The effectiveness of feature vector is enhanced by increasing the numbersGiven that random measurement matrix has defect in hardware realization, a scale-invariant feature transform (SIFT) based on polynomial deterministic matrix algorithm is proposed combining with the sparse projection of compressive sensing theory. The effectiveness of feature vector is enhanced by increasing the numbers of orientation gradient. The dimension of SIFT feature vector is decreased by a polynomial deterministic matrix with the measurement numbers of 7. Accordingly, the Euclidean distance is introduced to compute the similarity and dissimilarity between feature vectors used for image registration, and kd data structure is used to avoid exhaustion. Experimental results show that the proposed algorithm has better performance than the traditional SIFT algorithm and some current modified SIFT algorithms. At the same time, the deterministic matrix is beneficial to hardware implementation of image registration system..
Laser & Optoelectronics Progress
- Publication Date: Jul. 28, 2016
- Vol. 53, Issue 8, 81002 (2016)
Imaging Systems
Experiment of 2.52 THz Confocal Scanning 2D Axial Imaging Properties of Dual-Axis Reflection
Zhou Yi, and Li Qi
Terahertz dual-axis reflection confocal scanning imaging technique can penetrate nonpolar and non-metallic materials and then realizes high-resolution 3D imaging, thus it has wide research and application values. Its 2D imaging quality is greatly related to the axial position of the object. Experiments about the influeTerahertz dual-axis reflection confocal scanning imaging technique can penetrate nonpolar and non-metallic materials and then realizes high-resolution 3D imaging, thus it has wide research and application values. Its 2D imaging quality is greatly related to the axial position of the object. Experiments about the influence of the object axial position on the 2D imaging quality are carried out by utilizing 2.52 THz dual-axis reflection confocal scanning imaging system. Line contrast and area contrast are introduced to objectively evaluate the imaging quality. The subjective evaluation tallies with the objective evaluation basically..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2016
- Vol. 53, Issue 8, 81101 (2016)
High-Order Thermo-Optic Ghost Imaging for a Tangential Moving Target
Liang Zhenyu, Fan Xiang, Cheng Zhengdong, Zhu Bin, and Shi Zhan
In order to investigate the impact of light field high-order correlation on the tangential moving target ghost imaging, high-order background-subtracted ghost imaging theory can be applied. Some numerical simulations and experiments are carried out, and the relevant simulated images are obtained. In this study of tangeIn order to investigate the impact of light field high-order correlation on the tangential moving target ghost imaging, high-order background-subtracted ghost imaging theory can be applied. Some numerical simulations and experiments are carried out, and the relevant simulated images are obtained. In this study of tangential moving targets ghost imaging based on the high-order background-subtracted ghost imaging theory, the results show that the high-order correlation of the light field increases the background fluctuation noise when the reference beam order increases, and the quality of image reconstruction deteriorates. Moreover, the increase of the signal beam order has little effect on the image quality. So the best quality can be obtained by the lowest-order ghost imaging..
Laser & Optoelectronics Progress
- Publication Date: Jul. 26, 2016
- Vol. 53, Issue 8, 81102 (2016)
Instrumentation, Measurement and Metrology
Design and Performance Testing of Constant-Temperature Water Jacket Small-Scale Model of Lithographic Projection Lens
Peng Haifeng, Yu Xinfeng, and Qin Shuo
Constant-temperature water jacket is an important part of the lithographic lens working environment controlling system. A small-scale water jacket model is designed to research the key parameters and properties of constant-temperature water jacket. The constant-temperature water controlling system provides deionized waConstant-temperature water jacket is an important part of the lithographic lens working environment controlling system. A small-scale water jacket model is designed to research the key parameters and properties of constant-temperature water jacket. The constant-temperature water controlling system provides deionized water within ±0.001 ℃ to it, and the key parameters of small-scale water jacket is obtained by comparing the variation of three-mirror optical-mechanical system temperature and thermal aberration. The experimental data shows that when the thermal disturbance is introduced and the temperature of the environment is 22.06~22.16 ℃, the temperature of the inside barrel of the three-mirror optical-mechanical system can be controlled within (22±0.01) ℃. The wave aberration is restored to 10.12 nm after thermal aberration, which is almost equal to the status of the assembled and adjusted system. It shows that the structure of the water jacket can satisfy the demand of the temperature controlling for the projection lens. The equal proportion constant-temperature water jacket can be designed based on it..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2016
- Vol. 53, Issue 8, 81201 (2016)
High Precision Laser Position Detecting System Based on Position Sensitive Device
Cheng Zhi, Dong Dengfeng, Zhou Weihu, and Liu Xin
Non-contact photoelectric measuring method is important to realize micro-displacement measurement. Position sensitive device (PSD) is a kind of light spot position detecting sensor. Its detection accuracy and data processing method based on PSD can directly affect the location measurement accuracy. The working principlNon-contact photoelectric measuring method is important to realize micro-displacement measurement. Position sensitive device (PSD) is a kind of light spot position detecting sensor. Its detection accuracy and data processing method based on PSD can directly affect the location measurement accuracy. The working principle of PSD is that photocurrent intensity output from each electrode is inversely proportional to the distance between the position of the incident light and each electrode. According to this principle, the scheme of the two-dimensional laser position detecting system has been designed. In order to improve the stability of the output weak current signals from PSD and the location detection accuracy, signal conditioning circuit design, parameters matching, filtering method and real-time parallel algorithm are mainly studied. The experiment results indicate that, within ±2 mm square area, the stability accuracy of the single point of this detecting system based on PSD is better than 2 μm. Therefore, this system can satisfy the requirements of space target accurate positioning of the laser tracker in funded project and application requirements like real-time high accuracy micro-displacement measurement based on laser position detecting..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2016
- Vol. 53, Issue 8, 81202 (2016)
Accuracy Analysis of Intersection Measurement on Sailing Ships
Huang Shiliang, Hu Yabin, and Zhou Jun
Based on the principle of intersection measurement, a mathematical model is established to gauge the location and the size of the sailing ships, and the formula of measurement error is deduced. The distribution of the measurement error is simulated using Matlab software, and the main factors affecting the system measurBased on the principle of intersection measurement, a mathematical model is established to gauge the location and the size of the sailing ships, and the formula of measurement error is deduced. The distribution of the measurement error is simulated using Matlab software, and the main factors affecting the system measurement accuracy are analyzed. The measurement model is validated through the tests. The results show that it is feasible to use the intersection measuring principle to measure the location and the size of sailing ships. It also lays the foundation for further project application..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2016
- Vol. 53, Issue 8, 81203 (2016)
Lasers and Laser Optics
Temperature Field of Pulsed LD End-Pumped Square Yb:YAG Crystal with Variable Thermal-Conductivity
Geng Yingge, Li Long, Pan Xiaorui, and Fu Yiliu
The temperature field of a pulsed laser diode (LD) end-pumped Yb:YAG crystal with variable thermal conductivity is studied. A thermal conduction model with heat-insulted end faces and constant peripheral temperature is built. Based on the semi-analytical theory and by means of Newton′s method, the temperature field disThe temperature field of a pulsed laser diode (LD) end-pumped Yb:YAG crystal with variable thermal conductivity is studied. A thermal conduction model with heat-insulted end faces and constant peripheral temperature is built. Based on the semi-analytical theory and by means of Newton′s method, the temperature field distribution of the crystal is obtained. The influences of pump power, super-Gaussian order, spot radius, and crystal size on the temperature field are analyzed. The calculation results show that, when the crystal is pumped by a pulsed LD with super-Gaussian order of three, pump power of 80 W, and radius of 400 μm, and under the condition that the thermal-conductivity is constant or non-constant, the maximum temperature increase at the pumped end faces is 31.69 and 35.66 ℃, respectively. The research results provide certain theoretical guidance to the design of lasers..
Laser & Optoelectronics Progress
- Publication Date: Jul. 29, 2016
- Vol. 53, Issue 8, 81401 (2016)
Damage Properties of Single Pulse of Nanosecond Laser on Damping Rubber Material
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and Peter Bennett
To study the interactions of single nanosecond laser pulses with damping rubber materials, etch experiment is carried out by single pulsed laser. Damage situation of the material is observed and damage mechanism is analyzed. The results show that the heat generated by the laser energy is mostly focused on the spot areaTo study the interactions of single nanosecond laser pulses with damping rubber materials, etch experiment is carried out by single pulsed laser. Damage situation of the material is observed and damage mechanism is analyzed. The results show that the heat generated by the laser energy is mostly focused on the spot area due to the low heat transfer coefficient of the damping rubber material, while short pulsed laser energy affects on the surface of damping rubber material. As a result, thermal cracking and ageing of the rubber are apparent and a thermal ablation like honeycomb in the holes are shown under the condition of high temperature. The diameter and the depth of the holes are increased with the increasing of the single pulse energy and the ablation state of the rubber in the holes is more significant. The damage threshold of the 13 ns single laser pulse on the damping rubber material is calculated by measuring the ablation diameter and depth. The damaging process of the damping rubber material by a single laser pulse is simulated by the finite element method, and single pulse damage threshold of the material is calculated again with the simulation results. The result shows good agreement with the experiment result..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2016
- Vol. 53, Issue 8, 81402 (2016)
Process Study and Optimization of Laser Welding Optical Components
Yan Fei, and Zhang Kefei
With the simplified finite element model of optical components established by the software ANSYS, Gaussian heat as heat source model, and the nonlinear transient analysis, the weld temperature field distribution is numerically simulated. The variation laws of welding spot size and depth with laser beam radii and outputWith the simplified finite element model of optical components established by the software ANSYS, Gaussian heat as heat source model, and the nonlinear transient analysis, the weld temperature field distribution is numerically simulated. The variation laws of welding spot size and depth with laser beam radii and output powers are obtained accurately. The results show that the short-period pulse waveform can effectively improve the welding quality. The depth and width of welding spot increase with the increase of laser output power and decrease with the increase of laser beam radius. And the numerical simulation result is basically consistent with the actual situation, which verifies the applicability of the finite element model of optical components. The study provideds an effective experimental basis for the prediction and improvement of welding quality of optical components in different laser welding processes..
Laser & Optoelectronics Progress
- Publication Date: Jul. 28, 2016
- Vol. 53, Issue 8, 81403 (2016)
Experiment and Simulation of Manufacturing Microparts by Laser Indirect Shocking
Zhang Di, Liu Lihua, Guo Hua, and Chen Zhilan
One new method based on laser indirect shocking is proposed to manufacture microparts with high efficiency and high precision. Based on the indirect loading mechanism of laser shocking polymers, with different shapes of micromolds and NdYAG-GAIA R laser, it is realized to manufacture microparts on a 35 μm thick Ti sheeOne new method based on laser indirect shocking is proposed to manufacture microparts with high efficiency and high precision. Based on the indirect loading mechanism of laser shocking polymers, with different shapes of micromolds and NdYAG-GAIA R laser, it is realized to manufacture microparts on a 35 μm thick Ti sheet under only single laser impact. The experimentally obtained microparts are investigated by the digital measurement system (KEYENCE VHX-1000C), and it is found that within the suitable range of laser power, the microparts have good surface profile, and their forming depth are basically consistent with the pit depth of micromolds. Besides, the forming process of microparts and the thinning rate of the formed parts are investigated by the finite element numerical simulation. The experimental and simulation results show that the good quality microparts can be formed under the single laser impact..
Laser & Optoelectronics Progress
- Publication Date: Jul. 25, 2016
- Vol. 53, Issue 8, 81404 (2016)
High Precision Synchronous Trigger Technology Based On High Power Energy Petawatt System
Zhang Yanyan, Li Guoyang, Fan Wei, Wang Xiaochao, Jiang Youen, and Shi Zhidong
A high precision synchronization method is proposed to realize the application in Shenguang Ⅱ between petawatt short pulse and main compression pulse. The short pulse from mode-locked laser and main trigger signal is locked by the and gate, which is the key to achieve synchronization between long pulse and short pulse A high precision synchronization method is proposed to realize the application in Shenguang Ⅱ between petawatt short pulse and main compression pulse. The short pulse from mode-locked laser and main trigger signal is locked by the and gate, which is the key to achieve synchronization between long pulse and short pulse in high-power petawatt system of inertial confinement fusion. In the and gate, the main laser control signal from the front-end system works as the trigger signal of the field programmable gate array (FPGA) circuit. The output picosecond pulse from mode-locked laser is transformed into electrical pulse as well as synchronized and widened, then sent into FPGA as a clock signal. The root mean square of 26.3 ps is obtained between the trigger signal of main laser gate pulses and the short pulse, and the proposed technology can effectively improve the stability of the synchronization system in the device..
Laser & Optoelectronics Progress
- Publication Date: Jul. 25, 2016
- Vol. 53, Issue 8, 81405 (2016)
Analysis of Detonation in Chemical Laser Combustor
Wang Jie, Guo Jianzeng, Yan Feixue, and Fu Yuting
In order to evaluate the detonation influence in chemical laser combustor, the detonation from a lasing test in the deuterium fluoride (DF) laser is analyzed in depth. Numerical simulation of the detonation is conducted by the space-time conservation element and solution element (CE/SE) method. The simulation results iIn order to evaluate the detonation influence in chemical laser combustor, the detonation from a lasing test in the deuterium fluoride (DF) laser is analyzed in depth. Numerical simulation of the detonation is conducted by the space-time conservation element and solution element (CE/SE) method. The simulation results indicate that the instantaneous pressure in the combustor surges as the detonation takes place and spreads. The vibration, shock and torque acts resulting from the detonation lead to the maladjustment of the lasing resonator, which affects the normal running and lasing of the chemical laser. The results calculated from the simulation will play an important role in guiding the optimized design and the secure running of DF chemical lasers..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2016
- Vol. 53, Issue 8, 81406 (2016)
Numerical Simulation of Laser Attenuation in Laser Direct Metal Deposition
Zhang Dongyun, Zhang Huifeng, Dong Dongdong, and Liu Zhen
A comprehensive three-dimensional transient model is developed to analyze laser attenuation near substrate where the beam transmits through the converged titanium powder cloud. A ray tracing method is employed to calculate the intensity distribution in all the directions after the laser beam is partially absorbed and pA comprehensive three-dimensional transient model is developed to analyze laser attenuation near substrate where the beam transmits through the converged titanium powder cloud. A ray tracing method is employed to calculate the intensity distribution in all the directions after the laser beam is partially absorbed and partially scattered by the powder cloud. The effect of laser wavelength and number of particles on the laser attenuation process is considered. The results show that the spatially uniformly distributed titanium powder cloud with a concentration of 0.01 g/mL exhibits an absorptivity of 5.47%. The laser attenuation process due to the powder cloud is barely influenced by wavelength and the attenuation increases as the number of particles increases. The simulated transmittance of power cloud at 1.06 μm fits the transmittance curve of particulate suspension..
Laser & Optoelectronics Progress
- Publication Date: Jul. 21, 2016
- Vol. 53, Issue 8, 81407 (2016)
Thermocouple Time Constant Test System and Uncertainty Analysis Based on Semiconductor Lasers
Hao Xiaojian, Zhang Genfu, and Zan Qingbo
In view of the thermocouple time constant test, the semiconductor laser with 0.6 μs rise time and 500 W power is selected as the excitation source instead of the CO2 laser. By shaping the laser beam, 1050 ℃ step temperature at the measuring side of the thermocouple is achieved as the laser operates at 20 V working voltIn view of the thermocouple time constant test, the semiconductor laser with 0.6 μs rise time and 500 W power is selected as the excitation source instead of the CO2 laser. By shaping the laser beam, 1050 ℃ step temperature at the measuring side of the thermocouple is achieved as the laser operates at 20 V working voltage and 20 A working current. The measurement results are processed by wavelet denoising, and the measurement model is established. The uncertainty of the measurement results is evaluated by analyzing its sources. The measured time constant is 1.3268 s, and the expanded uncertainty is 1.12 ms. The time constant of large-range thermocouples can be tested through increasing the laser power and producing a higher step temperature at the measuring side of the thermocouple..
Laser & Optoelectronics Progress
- Publication Date: Jul. 21, 2016
- Vol. 53, Issue 8, 81408 (2016)
Materials
Surface Plasmon Resonance Properties of Silver Nanosphere Arrays
Zhang Ming, Lü Jingwei, Liu Zhaoting, Yang Lin, Chai Yating, and Wang Famei
The extinction spectra and electric field distribution of silver nanosphere arrays positioned in a line, plane or cube are calculated by discrete dipole approximation. It is demonstrated that the surface plasmon resonance peaks of extinction spectra are red-shifted with the increase of silver nanosphere diameter and blThe extinction spectra and electric field distribution of silver nanosphere arrays positioned in a line, plane or cube are calculated by discrete dipole approximation. It is demonstrated that the surface plasmon resonance peaks of extinction spectra are red-shifted with the increase of silver nanosphere diameter and blue-shifted with the increase of the number of nanospheres. The coupling effects of silver nanoparticles with different structures between arrays have a significant impact on their surface plasmon resonance mode. It is found that the electric field coupling effects of silver nanosphere arrays positioned in a plane, cube and line is weakened in the order, when the arrays have the same diameter. The spectral characteristics of nanosphere arrays are closely related to the changes of polarization state of the incident light..
Laser & Optoelectronics Progress
- Publication Date: Jul. 13, 2016
- Vol. 53, Issue 8, 81601 (2016)
Optical Design and Fabrication
Design and Instance of Sport Digital Video Fisheye Lens
Liu Yan, Han Min, Ju Rongbing, Kang Lianjie, Zhu Jiawei, and Ding Guilin
In order to meet the requirement of the ultra-wide angle and large view landscape, a compact structure fisheye lens system for the sport digital video is designed with the optical system design software CODE V and Zemax. The lens comprises 5 pieces of glass lenses and 3 pieces of plastic aspheric lens. The design resulIn order to meet the requirement of the ultra-wide angle and large view landscape, a compact structure fisheye lens system for the sport digital video is designed with the optical system design software CODE V and Zemax. The lens comprises 5 pieces of glass lenses and 3 pieces of plastic aspheric lens. The design result shows that the F-number is 2.2, field angle is 240°, the total length of the system is 23 mm, the half image height is 2.35 mm, and all of the field of view at half of Nyquist frequency (178 Lp/mm) are more than 0.15. The lens achieve high-resolution panoramic monitor. The projection detection result shows that the performance of the fisheye lens can meet the requirements..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2016
- Vol. 53, Issue 8, 82201 (2016)
Optical Devices
Design of Focusing Mechanism for Lightweight Dual-Band Aerial Camera
Zhang Hongwei, Xu Yulei, Li Quanchao, Tan Songnian, and Wang Zhongshi
The working environment of the lightweight dual-band aerial camera is very complicated. Due to the changes in the environment, the focal plane of the camera will produce different degrees of deviation. In order to ensure the imaging quality of the camera in the complex environment, it is necessary to correct the focal The working environment of the lightweight dual-band aerial camera is very complicated. Due to the changes in the environment, the focal plane of the camera will produce different degrees of deviation. In order to ensure the imaging quality of the camera in the complex environment, it is necessary to correct the focal plane of the camera, so a focusing mechanism is designed. The transmission mode of the focusing mechanism is a worm-ear and a eccentric cam. The rotation of the eccentric cam drives the focusing lens moving along optical axis direction to solve the problem of aerial camera defocus. The optimized focusing mechanism has a shape size of 96 mm×65 mm×62 mm. The precision analysis of the focusing mechanism is carried out in the effective working range. The transmission precision experiment and the sway precision experiment are also carried out. The experimental results show that the transmission precision of the focusing mechanism is 3.5 μm, and the maximum sway error is below ±3″. The focusing mechanism meets the requirements of the structure space size and focusing precision..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2016
- Vol. 53, Issue 8, 82301 (2016)
Anode Modification Method for Improving Light Emission Performance of Organic Light Emitting Diode
Xia Shuzhen, Wang Wenjun, Du Qianqian, Li Shuhong, Zhang Dong, Gao Xuexi, Wang Qingru, and Zhang Bingyuan
This research investigates the effect of buffer layer on the performance of organic light emitting diodes (OLED) by adding m-MTDATA as buffer layer between anode and hole transport layer NPB. The devices with ITO/m-MTDATA(d nm)/NPB(40-d nm)/Alq3(70 nm)/LiF(0.5 nm)/Al(40 nm) and ITO/ MoO3 (15 nm)/NPB(25 nm)/Alq3(70 nm)/This research investigates the effect of buffer layer on the performance of organic light emitting diodes (OLED) by adding m-MTDATA as buffer layer between anode and hole transport layer NPB. The devices with ITO/m-MTDATA(d nm)/NPB(40-d nm)/Alq3(70 nm)/LiF(0.5 nm)/Al(40 nm) and ITO/ MoO3 (15 nm)/NPB(25 nm)/Alq3(70 nm)/LiF(0.5 nm)/Al(40 nm) structures are prepared. The effects of m-MTDATA thickness on OLED brightness, current density, current efficiency and other properties are studied. It is found that the turn-on voltage of the device reduces from 13 V to 9 V when the thickness of the buffer layer is 15nm, and the maximum brightness of the device increases from 5900 cd/m2 to 16300 cd/m2, which is about 2.76 times as much as that of the device without buffer layer. The highest current efficiency also increases from 1.8 cd/A to 3.5 cd/A, which is 1.94 times as much as the device without buffer layer. Then the MoO3 buffer layer with the thickness of 15 nm is inserted in the device as a buffer layer between indium tin oxide(ITO) and NPB. Compared to m-MTDATA device with the same thickness, the turn-on voltage of the device with MoO3 buffer layer declines to 8 V, the maximum brightness is 13320 cd/m2, the maximum current density is 6030.74 A/m2, and the maximum current efficiency is 3.06 cd/A..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2016
- Vol. 53, Issue 8, 82302 (2016)
Remote Sensing and Sensors
Hyperspectral Image Classification Based on Joint Sparse Representation and Morphological Feature Extraction
Wang Jianing
In order to further improve the classification performance of sparse representation classification, a hyperspectral image (HSI) classification algorithm based on joint sparse representation with morphological feature extraction is proposed. To obtain the principle component images, the whole HSI is analyzed by principlIn order to further improve the classification performance of sparse representation classification, a hyperspectral image (HSI) classification algorithm based on joint sparse representation with morphological feature extraction is proposed. To obtain the principle component images, the whole HSI is analyzed by principle component analysis. The closing and opening operations are implemented on principle component images to extract the morphological features. Combining the original spectral and the morphological feature, the pixels in a local region around the central test pixel are simultaneously represented by a set of common atoms of new training dictionary. The classification of HSI is determined by computing the minimum reconstruction error between testing samples and training samples. Experimental results on AVIRIS and ROSIS HSI demonstrate that the effectiveness of the proposed method for improving the classification accuracy and performance..
Laser & Optoelectronics Progress
- Publication Date: Jul. 25, 2016
- Vol. 53, Issue 8, 82801 (2016)
A Method of Adaptive Feature Selection for Airborne LiDAR Point Cloud Classification
Zhang Aiwu, Xiao Tao, and Duan Yihao
In different terrain conditions, different feature combinations and dimensions have different influences on the effectiveness and accuracy of classification. A method is proposed to select the airborne LiDAR point cloud classification with adaptively feature selection. The whole point cloud is divided into different reIn different terrain conditions, different feature combinations and dimensions have different influences on the effectiveness and accuracy of classification. A method is proposed to select the airborne LiDAR point cloud classification with adaptively feature selection. The whole point cloud is divided into different regions in accordance with the terrain conditions, and the suitable feature set is selected adaptively for classification. In order to evaluate the effective of this method, the random forest method and support vector machine classification method are used to classify the experimental data with the feature set after optimization. Experimental result shows that the suitable feature set for classification in different areas are different. The proposed method can reduce the feature dimensions effectively, shorten time consumption, and achieve high classification accuracy..
Laser & Optoelectronics Progress
- Publication Date: Jul. 29, 2016
- Vol. 53, Issue 8, 82802 (2016)
Adaptive Estimation Method for Diameter at Breast Height Based on Terrestrial Laser ScanningBu Guochao
[in Chinese], and [in Chinese]
In order to automatically and accurately extract the diameter at breast height (DBH) of trees within a certain range from the single-station terrestrial laser scanning（TLS）, an adaptive circle-ellipse fitting DBH estimation method is proposed based on the point cloud slice. The forestry point cloud data at breast heighIn order to automatically and accurately extract the diameter at breast height (DBH) of trees within a certain range from the single-station terrestrial laser scanning（TLS）, an adaptive circle-ellipse fitting DBH estimation method is proposed based on the point cloud slice. The forestry point cloud data at breast height is sliced, the point cloud of the slice is clustered, and the proposed method is used to distinguish whether they are trunk points. DBH of the trunk point is calculated directly when the point conforms to the circular distribution, while DBH of the trunk point is calculated after breast height position correction when the point conforms to the elliptic distribution. The artificial willows data acquired in Beijing Dongsheng Country Park is used to verify the proposed method and compare it with the simple circular fitting method. The results show that the root mean square error of estimated DBH is 1.1 cm when the scanning distance is within 26 m, and it is 1.99 cm when the scanning distance is within 56 m. For the trees regarded as elliptic distribution, the mean error of DBH estimation results is 4.7% lower than that of the circular fitting results. The DBH can be detected quickly and efficiently with the proposed method..
Laser & Optoelectronics Progress
- Publication Date: Jul. 25, 2016
- Vol. 53, Issue 8, 82803 (2016)
Reviews
Review on Morphological Filtering Algorithms Based on LiDAR Digital Elevation Model Construction
Hui Zhenyang, and Hu Youjian
Digital elevation model acquisition is the precondition of smart city construction. The airborne LiDAR technology provides a new approach for building the digital elevation model. Accurate ground point cloud filtering is the key to constructing the digital elevation model, so filtering for airborne LiDAR point cloud haDigital elevation model acquisition is the precondition of smart city construction. The airborne LiDAR technology provides a new approach for building the digital elevation model. Accurate ground point cloud filtering is the key to constructing the digital elevation model, so filtering for airborne LiDAR point cloud has always been a research hotspot and difficulty. As the morphological algorithms are simple and efficient, they are the mainstream in the point cloud filtering. To deep understand the algorithms, we summarize existed morphological filtering algorithms at home and abroad, analyze the characteristics, resolved problems and unresolved problems of various filtering methods, and present the prospect of the algorithms based on the unresolved problems..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2016
- Vol. 53, Issue 8, 80001 (2016)
Research Progress in Thermal Effect of High Power Fiber Lasers
Hu Zhitao, He Bing, Zhou Jun, and Zhang Jianhua
Thermal effect of fiber lasers should be taken into account in order to achieve high power output. Research of the thermal distribution and the control measures available are of great significance for normal and stable operation of the high power fiber lasers. We review the primary reported studies related to thermal eThermal effect of fiber lasers should be taken into account in order to achieve high power output. Research of the thermal distribution and the control measures available are of great significance for normal and stable operation of the high power fiber lasers. We review the primary reported studies related to thermal effect of the high power fiber lasers, and introduce the fiber temperature theory, impact of the thermal effect on the output properties of fiber lasers, and the approaches for thermal effect controlling. Meanwhile, their merits and drawbacks are discussed, and the development prospect is predicted..
Laser & Optoelectronics Progress
- Publication Date: Jul. 15, 2016
- Vol. 53, Issue 8, 80002 (2016)
Progress in All-Solid-State Single-Frequency Lasers
Li Menglong, Gao Long, Shi Wenzong, Feng Wen, Yan Fanjiang, and Tao Yuliang
All-solid-state single-frequency lasers with long coherent length, narrow line width, high efficiency and long life time have been widely used in scientific, military and industrial fields in recent years. The key techniques to achieve the all-solid-state single-frequency laser output and improve the laser performance All-solid-state single-frequency lasers with long coherent length, narrow line width, high efficiency and long life time have been widely used in scientific, military and industrial fields in recent years. The key techniques to achieve the all-solid-state single-frequency laser output and improve the laser performance are single longitudinal mode selection and power amplification. The domestic and international progress in such lasers and the mainstream technology programs are analyzed and summarized. In addition, the prospect of the all-solid-state single-frequency laser is discussed..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2016
- Vol. 53, Issue 8, 80003 (2016)
Research Status of Flexible Electro-Optical Circuit for Interconnection
Mao Jiubing, Yang Wei, Feng Xiaojuan, and Li Jianping
As the latest development direction of the board-level optical interconnection, the flexible electro-optical printed circuit board (FEOPCB) not only has the great advantages of the optical interconnection, but also has the characteristics of the flexible printed circuit board. Which can realize the flexible interconnecAs the latest development direction of the board-level optical interconnection, the flexible electro-optical printed circuit board (FEOPCB) not only has the great advantages of the optical interconnection, but also has the characteristics of the flexible printed circuit board. Which can realize the flexible interconnection between the different subsystems, and meet the development tread of lightweight, compact and high performance for the high speed electronic system. The domestic and oversea research state of FEOPCB is introduced and analyzed in detail. The key technologies and the future research directions of the flexible interconnection circuit are discussed..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2016
- Vol. 53, Issue 8, 80004 (2016)
Current Status and Key Technologies of Unmanned Aerial Vehicle Laser Communication Payloads
Yan Lusheng, Wang Feng, Wu Wei, Liu Xiangnan, Chen Ming, and Huai Qiwu
The application requirements of unmanned aerial vehicle (UAV) laser communication technology are summarized, and the importance of UAV laser communication is illustrated. The research status at home and abroad and the performance characteristics of airborne laser communication technologies are discussed in detail, and The application requirements of unmanned aerial vehicle (UAV) laser communication technology are summarized, and the importance of UAV laser communication is illustrated. The research status at home and abroad and the performance characteristics of airborne laser communication technologies are discussed in detail, and the development trend is pointed out. Based on the discussion, the key technologies of UAV laser communication payloads are analyzed, and the corresponding solutions are proposed. The application prospect and challenges about UAV laser communication payloads are discussed. Predictably, the UAV laser communication technology will play an important role in the air and space integrated communication networks..
Laser & Optoelectronics Progress
- Publication Date: Jul. 23, 2016
- Vol. 53, Issue 8, 80005 (2016)
Application of Distributed Fiber Sensing in Fiber Lasers
Zhou Zichao, Wang Xiaolin, Su Rongtao, Zhang Hanwei, Zhou Pu, and Xu Xiaojun
Thermal effect in gain fibers is one of the major factors limiting the output power of high power lasers. Measuring the temperature of gain fibers with the distributed temperature sensing method is beneficial to protecting fiber lasers, and may provide a new approach to understand the underlying mechanisms of the mode Thermal effect in gain fibers is one of the major factors limiting the output power of high power lasers. Measuring the temperature of gain fibers with the distributed temperature sensing method is beneficial to protecting fiber lasers, and may provide a new approach to understand the underlying mechanisms of the mode instability (MI) and other nonlinear effects occurring in fiber lasers. Major technologies on distributed optical fiber sensing are introduced, with more focus on the applications of technologies, such as optical frequency domain reflectometry (OFDR), Brillouin optical time domain analysis (BOTDA), Brillouin optical frequency domain analysis (BOFDA), and Brillouin optical correlation domain analysis (BOCDA), in the measurements of temperature and stress in fiber lasers. Finally, the feasibility of some distributed sensing schemes is analyzed, which provides references for temperature measurement in high power fiber lasers..
Laser & Optoelectronics Progress
- Publication Date: Jul. 28, 2016
- Vol. 53, Issue 8, 80006 (2016)
Research Development Trends of Zoom System with Variable Focal Power Device
Cheng Hongtao, Guo Shijun, Lü Jie, and Li Hengyu
The principles of the development process of zoom optical system is analyzed based on the theory of zoom principle, we discuss the strong and weak points of each kind of zoom principle and their applications. Related technology of variable focal power device and current research focus of the optical power compensation The principles of the development process of zoom optical system is analyzed based on the theory of zoom principle, we discuss the strong and weak points of each kind of zoom principle and their applications. Related technology of variable focal power device and current research focus of the optical power compensation system are summarized. The theoretical design and future development of next generation of zoom systems are proposed..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2016
- Vol. 53, Issue 8, 80007 (2016)
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