2011
2011
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Record 133 of
Title:Propagation of coherent combination of flat-topped Gaussian beams in atmospheric turbulence
Author(s):Ye, Shunliu(1,2); Wang, Xu'an(2); Zhu, Shaolan(2); Chen, Youjie(2)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 40 Issue: 7 DOI: Published: July 2011Abstract:Beam combination is that laser output beams overlap in the far field, so as to realize the high power, high beam quality of laser output, which has a broad prospect of application in remote sensing, tracking and far distance optical communication. The far field propagation properties and energy centrality of the coherent combination of one-dimensional flat-topped Gaussian beam array through atmospheric turbulent were studied in detail in this paper. The analytical expressions for intensity propagation, power in the bucket (PIB) were derived based on the generalized huygens-fresnel principle. It is shown that coherently combined beam will finally turn into Gaussian-like profile in the far field with increasing the distance of combination beam. The turbulence leads to degradation of the maximum intensity of combination beam, the larger the beam order is, the larger the decrement is. The energy centrality will decrease as the turbulence intensity increases, the beam order increases, the fill factor decreases and the elements number increases.Accession Number: 20113614302210 -
Record 134 of
Title:SG diagnostic equipment: Gating pinhole framing camera
Author(s):Bai, Xiao-Hong(1,2); Bai, Yong-Lin(1); Liu, Bai-Yu(1); Qin, Jun-Jun(1); Zhao, Jun-Ping(1); Wang, Bo(1,2); Yang, Wen-Zheng(1); Gou, Yong-Sheng(1)Source: Guangxue Jingmi Gongcheng/Optics and Precision Engineering Volume: 19 Issue: 2 DOI: 10.3788/OPE.20111902.0367 Published: February 2011Abstract:In order to install an X-ray Pinhole Framing Camera (X-PFC) conveniently and run smoothly in the SG3 prototype system (SG3-PS) of Inertial Confinement Fusion (ICF), a novel type X-PFC was developed on the basis of original models and a conical barrel pinhole imaging system was desined to eliminate the stray light and to obtain the pinhole imaging in the SG3-PS. The matching parameters were evidently improved by designing a long micro-strip in new tube, which could keep the number of imagings to be still 16 frames in the limited space by using new type fluorescent screen, steady clamp method and the way of sealing up with two optics fiber plates. The save quality of new tube was improved greatly by gating pulse voltage on the screen. Furthermore, the high-voltage pulse generators and all of monitoring facilities were assembled in the cylinder barrel type vacuum seal configuration by PC104. Experiments show that all kinds of technical indexes have been upgraded when some parts of the new camera structure are redesigned and experimental results are received better.Accession Number: 20111713936103 -
Record 135 of
Title:Development of testing system for the stability of organic light emitting devices
Author(s):Zhang, Wenwen(1,2,3); Wu, Zhaoxin(2,3); Zhu, Renlong(2,3); Hou, Xun(1,2,3)Source: Hsi-An Chiao Tung Ta Hsueh/Journal of Xi'an Jiaotong University Volume: 45 Issue: 2 DOI: Published: February 2011Abstract:A novel testing system for stability of organic light emitting devices (OLED) is proposed to improve the circuital complexity and high cost of existing systems. The proposed system employs the high precision IC operational amplifiers to achieve driving power supply, and uses silicon photocells to capture brightness of OLED. Then an acquisition board based on PCI bus is used to obtain the data concerning the variation of brightness and voltage of OLED. The testing system can provide two different power sources, i. e. , a constant current source and a hybrid current-voltage source (a constant current source for direct bias and a constant voltage source for reverse bias). Silicon photocells are used to replace traditional brightness photometers so that costs are substantially reduced, while the use of the acquisition board based on PCI bus decreases development difficulty and shortens the development time. Testing results show that the system is competent to measure luminance delay and voltage raising, and is stable and reliable.Accession Number: 20111513898919 -
Record 136 of
Title:Preparation of a new type of high-resolution light source
Author(s):Dou, X.B.(1,2); Chen, X.(1,3); Bi, S.W.(1); Liu, W.Y.(1); Chen, M.R.(1,2); Chen, L.(1,2)Source: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Volume: 637 Issue: 1 SUPPL. DOI: 10.1016/j.nima.2010.02.040 Published: May 1, 2011Abstract:The generation of a new type of high-resolution non-classical light source with a wavelength of 1064 nm is demonstrated experimentally. A periodically poled KTiOPO4 (PPKTP) crystal is installed in a continuous-wave optical parametric amplifier (OPA), which is pumped by a 532 nm laser and seeded by a weak 1064 nm laser. The optical parametric down-conversion process is activated in the OPA and generates a non-classical optical field at a wavelength of 1064 nm. The partial squeezed spectrum is pre-detected by a homodyne detection setup. The experiment demonstrates that the resolution of the non-classical optical field is 1.43 times that of the classical optical field. ? 2010 Elsevier B.V. All rights reserved.Accession Number: 20112013983312 -
Record 137 of
Title:Characterization of vector diffraction-free beams
Author(s):Wang, Ting-Ting(1); Yang, Shuang-Yan(1); Li, Chun-Fang(1,2)Source: Optics Letters Volume: 36 Issue: 12 DOI: 10.1364/OL.36.002342 Published: June 15, 2011Abstract:It is observed that a constant unit vector denoted by I is needed to characterize a complete orthonormal set of vector diffraction-free beams. The previously found diffraction-free beams are shown to be included as special cases. The I-dependence of the longitudinal component of diffraction-free beams is also discussed. ? 2011 Optical Society of America.Accession Number: 20112614090811 -
Record 138 of
Title:A signal to noise ratio measurement for single shot laser pulses by use of an optical Kerr gate
Author(s):He, Junfang(1); Zhu, Changjun(2); Wang, Yishan(1); Cheng, Guanghua(1); Zou, Kuaisheng(1); Wu, Dengke(1); Xie, Xudong(3)Source: Optics Express Volume: 19 Issue: 5 DOI: 10.1364/OE.19.004438 Published: February 28, 2011Abstract:A new design of signal to noise ratio (SNR) measurement for single shot laser pulses, based on a stepped grating and an optical Kerr gate (OKG), is presented. A single shot laser pulse was simultaneously divided into multi-pulses in both time and space. Intensity-space distribution of laser multi-pulses, which was recorded with a CCD detector, was transformed into intensity-time distribution. Time resolution of 1.95 ps and detection time range of 42.9 ps were obtained, respectively. Moreover, optical spatial localization attenuators were introduced into optical path to acquire wide dynamic range in the SNR measurement and, as a result, the dynamic range has been extended remarkably. ? 2011 Optical Society of America.Accession Number: 20111013714652 -
Record 139 of
Title:High efficiency and high beam quality 3.467-μm KTA extracavity optical parametric oscillator
Author(s):Sun, Qibing(1,2); Liu, Hongjun(1); Huang, Nan(1); Ruan, Chi(1); Zhu, Shaolan(1); Zhao, Wei(1)Source: Microwave and Optical Technology Letters Volume: 53 Issue: 10 DOI: 10.1002/mop.26247 Published: October 2011Abstract:An efficient single resonant extracavity optical parametric oscillator is demonstrated based on a Type II noncritical phase matching KTA crystal.Under a pump power of 0.6 W and a pulse width of 13 ns, the average power of 86 mW at 3.467 μm is obtained with the pulse width of 6 ns and repetition rate of 100 Hz, corresponding to a conversion efficiency as high as 14% from 1.064 to 3.467 μm. The beam spatial profile for 3.467 μm is near TEM00 mode. The average power of 123 mW is also obtained with a multitransverse mode at the repetition rate of 200 Hz and an average power of 2.3 W of the pump laser. ? 2011 Wiley Periodicals, Inc.Accession Number: 20113014175986 -
Record 140 of
Title:Design of low-timing-jitter, stable picosecond optical-pulse source using an uncooled gain-switched Fabry-Perot semiconductor laser with external continuous-wave light injection
Author(s):Liu, Yuanshan(1); Zhang, Jian-Guo(2)Source: Microwave and Optical Technology Letters Volume: 53 Issue: 9 DOI: 10.1002/mop.26176 Published: September 2011Abstract:This paper presents the design of a low-timing-jitter, stable picosecond optical-pulse source, which is based on a low-cost, uncooled Fabry-Perot (FP) semiconductor laser in the gain-switching operation. The wavelength of the designed laser can be tuned from 1538 to 1554 nm under the condition of external continuous-wave (CW) light injection. The relationship between injection light power and timing jitter or between injection light power and pulse width of this gain-switched laser is studied experimentally. Our results show that the optical pulses with widths about 28 and 19 ps at the repetition frequencies of 2.5 and 5 GHz, respectively, are produced by an uncooled gain-switched FP semiconductor laser with timing jitter ≤600 fs, when the injection power and wavelength of an external CW light are appropriately chosen. The use of a 500-m dispersion-compensation fiber can easily compress the optical pulses from 26 to 7.7 ps. Moreover, the stability of an uncooled gain-switched FP laser is experimentally investigated, and a stable optical-pulse train at 5 GHz can be feasibly produced over 7 h of continuously working. ? 2011 Wiley Periodicals, Inc.Accession Number: 20112514078401 -
Record 141 of
Title:Arbitrary ROI-based wavelet video coding
Author(s):Lan, Xuguang(1); Zheng, Nanning(1); Ma, Wen(1); Yuan, Yuan(2)Source: Neurocomputing Volume: 74 Issue: 12-13 DOI: 10.1016/j.neucom.2011.01.012 Published: June 2011Abstract:This paper presents a novel arbitrary shape region of interest (ROI) coding for scalable wavelet video codec. The motion information of the ROIs is estimated by macroblock padding and polygon matching. The derived motion vectors are set as the motion trajectory of the samples to generate a one-dimensional temporal signal. This signal is then filtered to reduce the temporal redundancy using motion compensated temporal filtering for arbitrary shape ROI. Compared to traditional non-ROI coding, the reconstructed quality of the ROI coding can be significantly improved at low bit-rates. The efficiency of motion compensated temporal filtering (MCTF) based on arbitrary ROI is also compared with that of the video object coding in MPEG-4. Based on large number of experiments, the ability of the MCTF to reduce the temporal redundancy is demonstrated as better than (or at least comparable to) that of MPEG-4. ? 2011.Accession Number: 20112114000148 -
Record 142 of
Title:Optimal design of temporal resolution of soft X-ray picosecond framing cameras based on micro-channel plate
Author(s):Yang, Wenzheng(1); Bai, Yonglin(1); Bai, Xiaohong(1); Qin, Junjun(1); Liu, Baiyu(2); Wang, Bo(1)Source: Chinese Optics Letters Volume: 9 Issue: SUPPL. 1 DOI: Published: June 2011Abstract:The transit characteristics of gain electrons in the dynamic electric field in one micro-channel, the relation of the temporal resolution, and the gating electric pulse are discussed in detail. The simulation analyses provide guidance on how to select parameters of the gating electric pulse for designing the X-ray picosecond framing camera, based on micro-channel plates, especially with regard to the aspect of the temporal resolution of the camera. Certain experimental results are presented. ? 2011 Chinese Optics Letters.Accession Number: 20113214224371 -
Record 143 of
Title:Design and implementation of high-speed multiwavelength pyrometry measurement system based on CMOS image sensor
Author(s):Wang, Bo(1,2); Bai, Yonglin(1); Liu, Baiyu(1); Bai, Xiaohong(1); Yang, Wenzheng(1); Qin, Junjun(1); Gou, Yongsheng(1)Source: Chinese Optics Letters Volume: 9 Issue: SUPPL. 1 DOI: 10.3788/COL201109.S10304 Published: June 2011Abstract:The detonation temperature is measured both theoretically and experimentally by means of a complementary metal oxide semiconductors (CMOS) image sensor. An experimental system of multiwavelength temperature measurement based on CMOS image sensing technology is designed and realized. The instant spectral information of each moment is captured by row with the CMOS image sensor, depending on the unique characteristic of its rolling shutter. With the use of multiwavelength temperature measurement theory and by fitting spectrum emissivity through the regressive least square method, the color temperature of the detonation whose temperature is variable can be obtained continuously. The system is calibrated by measuring the standard spectrum of the laser. In our system, four time temperatures are measured within 10-μs detonation. Results show that the system has a higher measuring accuracy and speed, and can be applied in high-speed spectral information collection and storage during the detonation. ? 2011 Chinese Optics Letters.Accession Number: 20113214224374 -
Record 144 of
Title:Supervised Gaussian process latent variable model for dimensionality reduction
Author(s):Gao, Xinbo(1); Wang, Xiumei(1); Tao, Dacheng(2); Li, Xuelong(3)Source: IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics Volume: 41 Issue: 2 DOI: 10.1109/TSMCB.2010.2057422 Published: April 2011Abstract:The Gaussian process latent variable model (GP-LVM) has been identified to be an effective probabilistic approach for dimensionality reduction because it can obtain a low-dimensional manifold of a data set in an unsupervised fashion. Consequently, the GP-LVM is insufficient for supervised learning tasks (e.g., classification and regression) because it ignores the class label information for dimensionality reduction. In this paper, a supervised GP-LVM is developed for supervised learning tasks, and the maximum a posteriori algorithm is introduced to estimate positions of all samples in the latent variable space. We present experimental evidences suggesting that the supervised GP-LVM is able to use the class label information effectively, and thus, it outperforms the GP-LVM and the discriminative extension of the GP-LVM consistently. The comparison with some supervised classification methods, such as Gaussian process classification and support vector machines, is also given to illustrate the advantage of the proposed method. ? 2006 IEEE.Accession Number: 20111213849913