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浏览/检索结果: 共5条，第1-5条 帮助 已选(0)清除 条数/页：5101520253035404550556065707580859095100   排序方式：请选择作者升序作者降序题名升序题名降序发表日期升序发表日期降序提交时间升序提交时间降序 Single-Pixel THz Imaging Based on Optimization of Collimated Spot 会议论文 Nis, Serbia, October 20-22, 2021 作者:   收藏  |  浏览/下载：11/0  |  提交时间：2022/02/04 Compressed sensing  Measured collimated spot  Single-pixel  Terahertz imaging   Angular response of 'pin-hole' imaging structure measured by collimated beta source 期刊论文 science china technological sciences, 2013 Zou Hong; Luo Lin; Li ChenFang; Jia XiangHong; Xu Feng; Chen HongFei; Chen Jiang; Shi WeiHong; Yu XiangQian; Zou JiQing 收藏  |  浏览/下载：4/0  |  提交时间：2015/11/10 &apos  Energetic particle  Pitch-angle distribution  Angular response  beta source  Geant4 simulation  PITCH-ANGLE DISTRIBUTIONS  RELATIVISTIC ELECTRONS  MAGNETOSPHERE  ACCELERATION  SPECTROMETER  SPACECRAFT  PLASMA  STORMS  CRRES  pin-hole&apos  imaging   Generation of nondiffracting Bessel beam using digital micromirror device 期刊论文 APPLIED OPTICS, 2013, 卷号: 52, 期号: 19, 页码: 4566-4575 作者:  Gong, L;  Ren, YX;  Xue, GS;  Wang, QC;  Zhou, JH 收藏  |  浏览/下载：16/0  |  提交时间：2015/07/22 Far-field focusing of laser beam based on digital image processing techniques (EI CONFERENCE) 会议论文 Optoelectronic Imaging and Multimedia Technology, October 18, 2010 - October 20, 2010, Beijing, China Zhang H.-Y.; Zhao S.; Guo J.; Liu L.-S.; Tian Y.-Z. 收藏  |  浏览/下载：20/0  |  提交时间：2013/03/25 In order to lead the laser beam transmit in the atmosphere convergently  an experiment of laser focus at the distance of 450m and 300m has been operated in the outdoor place. The actual manipulations are as follows: Firstly  the laser was collimated by a beam expander  then the near-parallel laser beam was transmitted with a Galileo telescope system  and the distance between the concave lens and the convex lens can be tuned through a precise displacement platform  so the focus of the system changed due to the tiny displacement of the concave lens. Secondly  the average power of the laser spot can be measured using power meter  the power is 47.67mW and the standard deviation is 0.67mW while the focal length is 450m. Thirdly  the energy distribution was found through the laser beam analyzer. The spot images were saved using the beam analyzer  then the saved image can be processed with Matlab software afterwards. The function named EDGE and Sobel operator was used in the pre-processing of the saved image  then method of median filter was used in the course of image de-noising and 53H filter was adopted in the signal analysis. The diameter of laser spot was obtained by the method above  the diameter is 5.56mm and the standard deviation is 0.24mm. The spot center excursion is 0.56mm  it is 10.43% of the total diameter of the laser spot. At last  the key factors of the energy dissipation in the focusing system can be summarized as follows: restriction of the diffraction limit  attenuation in the atmosphere  geometrical aberration of optical system  and the diffraction limit and the geometrical aberration are significant in the three factors above  so we can reduce the impact of the both factors during the design of optical system. The reliable referenced data of the system design can be acquired through the primary experiment research. 2010 SPIE.