2015
2015
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Record 325 of
Title:Experimental investigation on laser performance of distributed side-pumping fiber amplifier
Author(s):Gao, Cong(1); Ni, Li(1); Wang, Xiaolong(1); Wang, Yuying(1); Wang, Zhen(1,2,3); Peng, Kun(1,2,3); Huang, Zhihua(1); Wang, Jianjun(1); Jing, Feng(1); Lin, Aoxiang(1)Source: 2015 11th Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2015 Volume: 4 Issue: DOI: 10.1109/CLEOPR.2015.7376298 Published: January 7, 2016Abstract:1+1 type distributed-side pumping active fibers were fabricated. Pumped with 976nm LD, over 1kW output power was achieved at 1064nm and 581W power was launched into the coupling unit via one port. ? 2015 IEEE.Accession Number: 20161502241187 -
Record 326 of
Title:Research on the detection capability of space camera
Author(s):Yao, Dalei(1,2); Xue, Jianru(1); Chen, Zhi(2); Wen, Yan(2); Jiang, Baotan(2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9795 Issue: DOI: 10.1117/12.2217517 Published: 2015Abstract:Detection capability of space camera is regarded as the principal parameter in the design of space camera. On the basis of the concept of signal-to-noise ratio (SNR) and through the research of principles and derivation of theories, detection capabilities under static condition and the condition of relative motion were analyzed and compared. With a set of typical parameters given, the change of detectable magnitude with the changes of parameters was investigated. Considering the real operating environment of space camera, the necessity of temperature control in the design of space camera was discussed. The theoretical analysis provides a reference for the design of space camera. ? 2015 SPIE.Accession Number: 20161702279054 -
Record 327 of
Title:Halide gas-phase-doping technique to fabricate large-mode-area laser fiber
Author(s):Peng, Kun(1,2,3); Wang, Yuying(1); Ni, Li(1); Wang, Zhen(1,2,3); Gao, Cong(1); Zhan, Huan(2,3); Wang, Jianjun(1); Jing, Feng(1); Lin, Aoxiang(1)Source: 2015 11th Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2015 Volume: 2 Issue: DOI: 10.1109/CLEOPR.2015.7376103 Published: January 7, 2016Abstract:By using rare-earth-halide gas-phase-doping technique, we fabricated Yb-doped large-mode-area fiber preform. Yb concentration is of ～9500ppmw in core area and 951W@1064nm laser output was obtained with a slope efficiency of 83.3%. ? 2015 IEEE.Accession Number: 20161502242032 -
Record 328 of
Title:Research progress of chelate precursor doping method to fabricate Yb-doped large-mode-area silica fibers for kW-level laser
Author(s):Wang, Zhen(1,2,3); Zhan, Huan(3); Ni, Li(3); Peng, Kun(1,2,3); Wang, Xiaolong(3); Wang, Jianjun(3); Jing, Feng(3); Lin, Aoxiang(3)Source: Laser Physics Volume: 25 Issue: 11 DOI: 10.1088/1054-660X/25/11/115103 Published: November 2015Abstract:With continuous efforts and practical managing experiences, the chelate precursor doping method has been justified as an effective way to dope rare-earth ions into silica host materials, a key technique in making large-mode-area silica fibers for high power laser applications. It is characterized by good controllability, stability and repeatability to accomplish different refractive index profiles. Different preforms with a large core, designed refractive index profile, good symmetrical shape and homogeneous elemental distribution were successfully fabricated. The home-made standard 20/400-type double-cladding Yb-doped large-mode-area silica fiber was drawn and presented a 1.6 kW laser output at 1064 nm, the highest power record publically reported with this method. With further optimization, chelate precusor doping method has potential to manufacture high power laser fibers for the next generation. ? 2015 Astro Ltd.Accession Number: 20160801956184 -
Record 329 of
Title:Simultaneous pose and correspondence estimation based on genetic algorithm
Author(s):Yang, Haiwei(1); Wang, Fei(1); Li, Zhe(2); Dong, Hang(1)Source: International Journal of Distributed Sensor Networks Volume: 2015 Issue: DOI: 10.1155/2015/828241 Published: 2015Abstract:Although several algorithms have been presented to solve the simultaneous pose and correspondence estimation problem, the correct solution may not be reached to with the traditional random-start initialization method. In this paper, we derive a novel method which estimates the initial value based on genetic algorithm, considering the influences of different initial guesses comprehensively. First, a set of random initial guesses is generated as candidate solutions. Second, the assignment matrix and the perspective projection error are computed for each candidate solution. And then each individual is modified (selection, crossover, and mutation) in current iterative process. Finally, the fittest individual is stochastically selected from the final population. With the presented initialization method, the proper initial guess could be first calculated and then the simultaneous pose and correspondence estimation problem could be solved easily. Simulation results with synthetic data and experiments on real images prove the effectiveness and robustness of our proposed method. ? 2015 Haiwei Yang et al.Accession Number: 20154701591517 -
Record 330 of
Title:WS2/fluorine mica (FM) saturable absorbers for all-normal-dispersion mode-locked fiber laser
Author(s):Li, Lu(1,3); Jiang, Shouzhen(2); Wang, Yonggang(1); Wang, Xi(1); Duan, Lina(1); Mao, Dong(4); Li, Zhen(2); Man, Baoyuan(2); Si, Jinhai(3)Source: Optics Express Volume: 23 Issue: 22 DOI: 10.1364/OE.23.028698 Published: November 2, 2015Abstract:The report firstly propose a new WS2 absorber based on fluorine mica (FM) substrate. The WS2 material was fabricated by thermal decomposition method. The FM was stripped into one single layer as thin as 20 μm and deposited WS2 on it, which can be attached to the fiber flank without causing the laser deviation. Similar to quartz, the transmission rate of FM is as high as 90% at near infrared wavelength from one to two micrometers. Furthermore, FM is a highly elastic material so that it is not easy to break off even its thickness was only 20 μm. On the contrary, quartz is hard to be processed and easy to break off when its thickness is less than 100 μm. Compared to organic matrix such as polyvinyl alcohol (PVA), FM has higher softening temperature, heat dissipation and laser damage threshold than those of organic composites. In our work, the modulation depth (MD) and non-saturable losses (NLs) of this kind of saturable absorber were measured to be 5.8% and 14.8%, respectively. The WS2/FM absorber has a high damage threshold of 406 MW/cm2, two times higher than that of WS2/PVA. By incorporating the saturable absorber into Yb-doped fiber laser cavity, a mode-locked fiber laser was achieved with central wavelength of 1052.45 nm. The repetition rate was 23.26 MHz and the maximum average output power was 30 mW. The long term stability of working was proved to be good too. The results indicate that WS2/FM film is a practical nonlinear optical material for photonic applications. ?2015 Optical Society of America.Accession Number: 20160701940298 -
Record 331 of
Title:Colorimetric pyrometry system design and calibration experiment
Author(s):Chen, Yaohong(1); Liu, Wei(1); Fan, Zheyuan(1); Ren, Long(1); Yi, Bo(1); Xie, Qingsheng(1); Duan, Chengpeng(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9449 Issue: DOI: 10.1117/12.2075515 Published: 2015Abstract:In order to solve the problem of the existing single waveband thermal imaging system can?t get precise temperature of object with emissivity unknown, an optical system of beam splitting lens and filter were used to established a colorimetric temperature measurement system based on infrared thermal imaging system. Completed the compensation for non-effective pixel, enhancement of contrast, calibration of nonhomogeneity and coherence for infrared thermal imaging system according to the application requirement, then acquired the calibration data with blackbody as radiation source at 200°～500° and fit it. A temperature measurement test performed at last, compared with the result acquired by thermocouple and single waveband thermal imaging system, it was shown that the colorimetric pyrometry system achieve the attractive precision after calibration and applied to measure the temperature of the object with emissivity unknown. ? 2015 SPIE.Accession Number: 20151100635590 -
Record 332 of
Title:Adaptive blind pixel detection and compensation for IRFPA based on fuzzy median filter
Author(s):Leng, Hanbing(1); Gong, Zhendong(1); Xie, Qingsheng(1); Fan, Zheyuan(1); Wu, Dengshan(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 44 Issue: 3 DOI: Published: March 25, 2015Abstract:Blind pixels of IRFPA consist of fixed bad pixel and random bad pixel, the former is caused by material and manufacture defect, while the latter is mainly caused by temperature drift. Scene -based blind pixel detection and compensation algorithm is the effective method to eliminate these bad pixels and increase image quality. Aiming at the defect that the current filter-based detection methods can't distinguish random blind pixels and weak point targets, the response and noise feature of random blind pixels were first analyzed, and a new adaptive blind pixel detection and compensation algorithm based on fuzzy median and temporal accumulation was proposed. Fuzzy median filter was used to extract the potential blind pixels from scenes, then the exact distribution of fixed and random blind pixels were determined by temporal accumulation, and blind pixel compensation was performed finally. The experiments show that the proposed algorithm can effectively correct bad pixels while avoid misjudging weak point targets. ?, 2015, Chinese Society of Astronautics. All right reserved.Accession Number: 20151800813101 -
Record 333 of
Title:Measurement of defocused spot parameters of optical system
Author(s):Li, Kun(1); Chen, Yong-Quan(1); Zhao, Jian-Ke(1); Duan, Ya-Xuan(1); Li, Qiao-Ling(1); Pan, Liang(1); Long, Jiang-Bo(1); Zhang, Hai-Yang(1)Source: Guangxue Jingmi Gongcheng/Optics and Precision Engineering Volume: 23 Issue: 9 DOI: 10.3788/OPE.20152309.2482 Published: September 1, 2015Abstract:Defocused spot parameters of an optical system were measured by a testing system with CCD microscopic imaging quantitatively, and an evaluating method for the defocused spot parameters was designed. Firstly, the definitions of the defocused spot parameters including the diameter and the roundness were given. The connected region shaped by the energy contour of the defocused spots was analyzed, and the diameter equal to the area which is 80% of the total energy of the defocused spots was calculated. Then, the boundary of the region was fitted as an ellipse and the roundness of defocused spot was obtained. The method introduces the ellipse fit into the defocused spot roundness measurement through analysis of the energy distribution of star point image on image plane, so that the effects of CCD noise and stray light in test environment on the measuring results are reduced and the confidence of the test results is improved. The experimental results show that the repeatability of the diameter is 0.18 μm and that of the roundness is 1.65%. The method meets the needs of the optical systems in space projects for the imaging quality control. ?, 2015, Chinese Academy of Sciences. All right reserved.Accession Number: 20154401475320 -
Record 334 of
Title:Dynamic extracting and compensation of system error for rotary inductosyn
Author(s):Yuan, Hui(1); Liu, Zhao-Hui(1); Li, Zhi-Guo(1); Cui, Kai(1); Xie, You-Jin(1)Source: Guangxue Jingmi Gongcheng/Optics and Precision Engineering Volume: 23 Issue: 3 DOI: 10.3788/OPE.20152303.0794 Published: March 1, 2015Abstract:As the precision of a photo-turntable control system using rotary inductosyn depends on the dynamic angular position measuring precision of a rotary inductosyn, this paper explores the system error of the rotary inductosyn. The error mechanism of rotary inductosyn was analyzed, and the system error of the rotary inductosyn was quantitatively and dynamically measured by using an experimental platform. Finally, the system error model of the rotary inductosyn was put forward based on the data processing and error mechanism, and the output signals from the rotary inductosyn were compensated by the error model. The software compensation method was verified and the experimental results for the rotary inductosyn with 720 poles, 12 bits show that the dynamic angle measurement accuracy is improved from 11.25″ to 1.17″, while the angular velocity estimation accuracy is improved from 0.72(°)/s to 0.09(°)/s. The test results show that the proposed method improves the dynamic measuring accuracy of the rotary inductosyn significantly and satisfies the accuracy demands of photoelectric platform pointing control systems. ?, 2015, Chinese Academy of Sciences. All right reserved.Accession Number: 20151800797164 -
Record 335 of
Title:Research and implementation of large field image real-time mosaic technology based on FPGA
Author(s):Yang, Lei(1); Ren, Long(1); Liu, Qing(1); Wang, Hua(1); Zhou, Zuofeng(1); Cao, Jianzhong(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 44 Issue: 6 DOI: Published: June 25, 2015Abstract:As a general rule, the software method is used to obtain large field images, which is not timely and convenient. In order to tackle the disadvantage of this method, based on FPGA, a kind of programmable technologies, a large field of view imaging system had put forward and achieved, which can fulfill the real time stitching of the data from multiple cameras. Through the APTINA's color CMOS image sensor MT9M034, the original image information had gained and then the real time data collection, data cache, stitching and transmission had accomplished centering on the Xilinx's Virtex-5 FPGA. Firstly, the automatic adjustment of brightness differences of the original images was preprocessed in order to improve the overall mosaic effect. Secondly, information detection of relative shift amount was completed by the use of phase correlation method to register the original images. Finally, the two adjacent images' overlap area was fused by the use of linear weighted fusion algorithm to make the mosaic image achieve a smoothly fading in and out transitional effect. Experimental results show that the imaging system is simple and reliable, and can effectively increase the field of view of observation. The stitched large field images are of high-definition and real time, with a certain degree of representativeness and practicality. ?, 2015, Chinese Society of Astronautics. All right reserved.Accession Number: 20153501219877 -
Record 336 of
Title:All-phase target reconstruction method for coherent field imaging
Author(s):Cao, Bei(1); Luo, Xiu-Juan(1); Chen, Ming-Lai(1); Zhang, Yu(1)Source: Wuli Xuebao/Acta Physica Sinica Volume: 64 Issue: 12 DOI: 10.7498/aps.64.124205 Published: June 20, 2015Abstract:Received signal processing and target reconstruction technique plays a key role in coherent field imaging, and directly influences the quality of the reconstructed image of a target. Based on all-phase fast Fourier transformation (FFT) spectrum analysis theory, a new processing and reconstruction method is proposed. By directly extracting the phase and amplitude information from all-phase FFT spectrum of the return signal, the proposed all-phase target reconstruction method is capable of inhibiting the frequency error caused by many factors, thus reconstructing the target image more precisely. The validity of the proposed method is proved by a coherent field imaging system in outdoor environments, and it has a better reconstruction performance than a traditional method. The resolution of the reconstructed target is close to a theoretical diffraction limit. ?, 2015, Chinese Physical Society. All right reserved.Accession Number: 20153001051144