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Record 253 of
Title:Temporal contrast measurement of a single-shot laser pulse by optical pulse replication
Author(s):Yuan, Suochao(1); Gao, Limin(1); Li, Dongjian(1); Zhao, Juanning(1,2)
Source: Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams Volume: 26 Issue: 5 DOI: 10.11884/HPLPB201426.051016 Published: 2014
Abstract:For the measurement of the time profile and the contrast information of the ultrashort laser pulse, based on the third-order intensity correlation principle, using optical pulse replication, a measurement method is proposed. Theoretical analysis is made about the measurement method. The simulation was done with split-step Fourier and Runge-Kutta methods. By measuring the pulse with pieces of windows and piecing the windows together, the measuring range can be enlarged. Thus a high resolution and large window measurement is achieved. The pre-pulse and main pulse are separated into different windows to avoid the use of gradient attenuator, and provides high-contrast measurement capability.
Accession Number: 20142417824634
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Record 254 of
Title:Analyses on limitations of coherent field imaging principle
Author(s):Si, Qing-Dan(1,2); Luo, Xiu-Juan(1); Zeng, Zhi-Hong(1,2)
Source: Wuli Xuebao/Acta Physica Sinica Volume: 63 Issue: 10 DOI: 10.7498/aps.63.104203 Published: May 20, 2014
Abstract:The theoretical basis of coherent field imaging technique (also called the Fourier telescopy) is reconsidered. The limitations of the technique principle are analyzed by defining the measured object and deriving rigorously mathematical expressions. The reconstructed image of the technique ineluctably contains the gradient information about the object; as a result the technique cannot acquire the reflectivity of the object exactly. The computer simulation verifies the conclusion. Based on the conclusion, the reconstructed image of the technique can be evaluated and three-dimensional coherent field imaging technique may be developed. ? 2014 Chinese Physical Society.
Accession Number: 20142217774922
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Record 255 of
Title:Diode-pumped continuous wave and passively qswitched tm, mg: Litao3 lasers
Author(s):Feng, T.(1); Li, T.(1); Zhao, S.(1); Li, Q.(1); Yang, K.(1); Zhao, J.(1); Qiao, W.(1); Hang, Y.(3); Zhang, P.(3); Wang, Y.(4); Xu, J.(2)
Source: Optics Express Volume: 22 Issue: 4 DOI: 10.1364/OE.22.003818 Published: February 24, 2014
Abstract:We have demonstrated the continuous wave and passively Qswitched Tm, Mg: LiTao3 lasers for the first time. In continuous wave (CW) regime, a maximum CW output power of 1.03 W at 1952 nm was obtained, giving a slope efficiency of 9.5% and a beam quality M2 = 2.2. Inpassive Q-switching regime, a single walled carbon nanotube (SWCNT) was employed as saturable absorber (SA). The Tm,Mg:LiTao3 laser has yielded a pulse of 560 ns under repetition rate of 34.2 kHz at 1926 nm, corresponding to a single pulse energy of 10.1 μJ. The results indicate a promising potential of nonlinear crystals in the applications for laser host materials. ? 2014 Optical Society of America.
Accession Number: 20141017429327
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Record 256 of
Title:The design of freeform surface Fresnel lens used for LED uniform illumination
Author(s):Dai, Yi Dan(1,2); Qu, En Shi(1); Ren, Li Yong(1); Du, Xin Chao(1,2); Ju, Hai Juan(1)
Source: Applied Mechanics and Materials Volume: 571-572 Issue: DOI: 10.4028/www.scientific.net/AMM.571-572.976 Published: 2014
Abstract:This paper presents a new kind of light emitting diode(LED) secondary light distribution lens which adopts the type of Fresnel lens surface. The research purpose of this paper is to improve the LED heat dissipation efficiency of the secondary light distribution lens and the light efficiency, so as to prolong the service life of the LED. In this paper, we use the numerical method for solving the partial differential equation to establish a freeform surface lens which could produce uniform illumination, then the innovative method of combine the Fresnel lens structure with freeform surface lens was proposed. The design of freeform surface Fresnel lens allows dramatically cut the thickness of the lens (as well as the weight and volume), it can solve the problem of difficulty in heat dissipation. By comparing the ray tracing simulation results of original freeform surface lens and freeform surface Fresnel lens in optical simulation software, experiments show that the latter not only shows the same degree of illumination uniformity, but also greatly reduced the thickness of the lens. ? (2014) Trans Tech Publications, Switzerland.
Accession Number: 20142717905018
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Record 257 of
Title:Design of transient light signal simulator based on FPGA
Author(s):Kang, Jing(1,2); Chen, Rong-Li(1); Wang, Hong(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9299 Issue: DOI: 10.1117/12.2070215 Published: 2014
Abstract:A design scheme of transient light signal simulator based on Field Programmable gate Array (FPGA) was proposed in this paper. Based on the characteristics of transient light signals and measured feature points of optical intensity signals, a fitted curve was created in MATLAB. And then the wave data was stored in a programmed memory chip AT29C1024 by using SUPERPRO programmer. The control logic was realized inside one EP3C16 FPGA chip. Data readout, data stream cache and a constant current buck regulator for powering high-brightness LEDs were all controlled by FPGA. A 12-Bit multiplying CMOS digital-to-analog converter (DAC) DAC7545 and an amplifier OPA277 were used to convert digital signals to voltage signals. A voltage-controlled current source constituted by a NPN transistor and an operational amplifier controlled LED array diming to achieve simulation of transient light signal. LM3405A, 1A Constant Current Buck Regulator for Powering LEDs, was used to simulate strong background signal in space. Experimental results showed that the scheme as a transient light signal simulator can satisfy the requests of the design stably. ? 2014 SPIE.
Accession Number: 20150800545955
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Record 258 of
Title:Laboratory simulation of atmosphere turbulence for Fourier telescopy
Author(s):Zeng, Zhi-Hong(1,2); Luo, Xiu-Juan(1); Wang, Bao-Feng(1,2); Xia, Ai-Li(1); Cheng, Zhi-Yuan(1,2); Si, Qing-Dan(1,2)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 43 Issue: 6 DOI: 10.3788/gzxb20144306.0601002 Published: June 2014
Abstract:Fourier telescopy is a sort of high-resolution imaging technology for deep space object which is very small and dim. To verify the atmosphere turbulence net effect on Fourier telescope, the experimental demonstrations of atmosphere turbulence simulation were performed in a lab. Based on the laboratory system of three-beam Fourier telescope, the scintillation and the phase jitter were simulated by changing the radio-frequency driver output power and the instantaneous frequency, respectively. The detail of the experimental principle was presented, and the relation between the turbulent intensity and experimental variable was built. For different cases with random scintillation and phase jitter in weak turbulence, the experiments were conducted for single beam and three beams, and all the results' Strehl ratio were calculated. The experimental results indicate that, with single beam holding turbulence, there are no obvious change for all the reconstructed image; with three beams adding turbulence, the image quality of the Fourier telescope system is few influenced by weak scintillation, but is severe affected by phase jitter. As indicated, removing the phase and light intensity jitter effect is a key point of improving the image reconstruction arithmetic.
Accession Number: 20142917960009
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Record 259 of
Title:Parallel programming design of star image registration based on GPU
Author(s):Chen, Xi(1,2); Qiu, Yuehong(1); Yi, Hongwei(1)
Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 43 Issue: 11 DOI: Published: November 25, 2014
Abstract:The speed of star image registration affects the whole speed of the processing of the star image as star image registration is one of the most important steps of star image processing. In recent years, the general purpose computing of graphic process unit(GPU)has a rapid development. In this paper, the computing power of GPU for the general purpose computing and the problem of the speeding up of processing of star image registration were combined to study the accelerated processing algorithm based on GPU. A parallel model of GPU for the registration algorithm was proposed and CUDA programming language was uesd to realize it. Experiment result shows that the parallel model also fulfills the purpose of the image registration and has a 29.043X speedup compared with the serial CPU program. ?, 2014, Chinese Society of Astronautics. All right reserved.
Accession Number: 20150300435925
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Record 260 of
Title:New design method of precise space replicated light-tube
Author(s):Yin, Xunlong(1,2); Wu, Yiming(1); Wu, Cuigang(1); Yao, Zhen(1,2)
Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 43 Issue: 11 DOI: Published: November 25, 2014
Abstract:During the calibration and regulation of star simulator inertial measurement unit equipment, the parameter what is the azimuth angle between emergence beam from star simulator and reflected beam of inertial measurement prism is required. The directions of two beams are opposite and there are some space translation in them. The systems require a space replication light-tube for the measurement of the parameter with one theodolite. A new method was proposed for the design of replication light-tube, the light-tube can make the light pace replicate 180 in the horizontal plane and have a two dimensional translation in the plane perpendicular to the optical axis of the star simulator. Right angle roof prism and rhombic prism were used in the design of the light-tube for the purpose to eliminate the installation error of the tube. A double wedges instrument was designed to improve the accuracy of the light-tube. With the use of double wedges, the light pace could title lightly, so the transfer deviation could be eliminated. Experimental results show that the design can not only meet the requirements of the optical path and guarantee delivery accuracy, but also reduce processing costs of the precise replicated light-tube. ?, 2014, Chinese Society of Astronautics. All right reserved.
Accession Number: 20150300435921
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Record 261 of
Title:Performance of diode-pumped continuous wave tunable and passively Q-switched Nd,Mg:LiTaO3 laser
Author(s):Feng, T.(1); Li, T.(1); Zhao, S.(1); Li, Q.(2); Yang, K.(1); Zhao, J.(1); Qiao, W.(1); Hang, Y.(3); Zhang, P.(3); Wang, Y.(4); Xu, J.(2)
Source: Optics Communications Volume: 325 Issue: DOI: 10.1016/j.optcom.2014.03.088 Published: August 30, 2014
Abstract:The lasing characteristics of Nd,Mg:LiTaO3 crystal is demonstrated in this paper. The continuous wave laser spectra can be tuned from 1079.8 nm to 1083.1 nm and 1089.6 nm to 1093.2 nm. By employing a single-walled carbon nanotube (SWCNT) as saturable absorber (SA), the shortest pulse duration of 380 ns under repetition rate of 103 kHz is obtained, corresponding to a single pulse energy of 3.2 μJ. ? 2014 Elsevier B.V.
Accession Number: 20141817648651
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Record 262 of
Title:Reaserch on loss of fiber optic rotary joint based on virtual prototype
Author(s):Zhang, Min-Rui(1,2); He, Zheng-Quan(1); Hu, Bao-Wen(1); Kong, De-Peng(1); Du, Xin-Chao(1,2); Tian, Jin-Shou(1); Li, Yu-Lin(1)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 43 Issue: 12 DOI: 10.3788/gzxb20144312.1222001 Published: December 1, 2014
Abstract:A fiber optic rotary joint loss analysis method based on virtual prototype was proposed. The input-output equations of light in dove prism are derived. A hybrid architecture based on ray tracing model and analytical model was employed in a homogeneous coordinate system; the angle and position deviations of collimating lens and dove prism were considered as input error in the model as well as bearing clearance and gear precision. 30000 random samples, of which angle precision is ±100″ and position precision is ±0.01 mm, were studied. The result shows that angle error of dove prism and collimating lens must be ±1' or less while the maximum loss is required less than 4dB, the distribution of loss P(X?3 dB) is required less than 0.5%. ?, 2014, Chinese Optical Society. All right reserved.
Accession Number: 20150300425648
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Record 263 of
Title:Magneto-optical modulation method for measuring glass internal stress
Author(s):Li, Chun-Yan(1,2); Wu, Yi-Ming(1); Gao, Li-Min(1); Lu, Wei-Guo(1,2); Xiao, Mao-Sen(1)
Source: Guangxue Jingmi Gongcheng/Optics and Precision Engineering Volume: 22 Issue: 1 DOI: 10.3788/OPE.20142201.0058 Published: January 2014
Abstract:A measuring method for the internal stress magnitude and direction of glass was proposed based on the magneto-optical modulation and a stress measuring system was established. On the basis of the ray-tracing method, the system's measurement model was derived according to the Jones matrix describing manner of polarized light. Then, using a magneto-optical modulator, the signal beam was modulated with a sine alternation manner and the direct measurement of the light intensity signal in the traditional method was changed into the frequency signal measurement to improve the measurement veracity greatly. Furthermore, the human operator error was eliminated through a magneto-optical rotator, and the current for driving a coil outside the rotator was controlled to change the rotation angle of modulation signal light in the polarization direction. Finally, a number of rotating measurements to the sample were carried out. The experimental results indicate that the measurement veracities for stress direction, and the stress birefringence are 5" and 0.3 nm/cm, respectively. In conclusions, the system has the characteristics of high stability, high veracity and easy to be implemented in engineering applications.
Accession Number: 20140717331108
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Record 264 of
Title:Hybrid structure for robust dimensionality reduction
Author(s):Lu, Xiaoqiang(1); Yuan, Yuan(1)
Source: Neurocomputing Volume: 124 Issue: DOI: 10.1016/j.neucom.2013.07.019 Published: January 26, 2014
Abstract:In recent years, dimensionality reduction has attracted a great deal of attention in the communities of machine learning and data mining. The basic goal of dimensionality reduction is to discover the low dimensional manifold embedded in a high dimensional space. Although some existing manifold learning algorithms (ISOMAP, LE, LLE, LTSA, etc.) can capture the local structure of data manifold, they have poor performance in some recognition tasks. This is mainly because that they cannot handle well with the "out of sample" problem. Moreover, these algorithms are sensitive to the choice of nearest neighbors, which is crucial in classification. To address these problems, this paper proposes a Robust Dimensionality Reduction Algorithm With Local and Global Structure (RLGS) based on a novel adaptive weighting mechanism. Hybrid structure of local and global structures is studied. By using the adaptive weight, RLGS has the capacity of adaptively exploiting non-linear structure of data manifold and is robust to parameters. Experiments demonstrate that RLGS performs better on public face databases compared with other reported algorithms. ? 2013 Elsevier B.V.
Accession Number: 20134316889883
