中国科学院机构知识库网格
Chinese Academy of Sciences Institutional Repositories Grid
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Lithospheric structures across the Qiman Tagh and western Qaidam Basin revealed by magnetotelluric data collected using a self-developed SEP system 期刊论文  OAI收割
SCIENCE CHINA-EARTH SCIENCES, 2021, 页码: 8
作者:  
Di, Qingyun;  Xue, Guoqiang;  Wang, Zhongxing;  He, Lanfang;  Pei, Renzhong
  |  收藏  |  浏览/下载:49/0  |  提交时间:2021/10/21
An open system design of high speed image transmission (EI CONFERENCE) 会议论文  OAI收割
1st International Symposium on Computer Network and Multimedia Technology, CNMT 2009, December 18, 2009 - December 20, 2009, Wuhan, China
作者:  
Li S.
收藏  |  浏览/下载:26/0  |  提交时间:2013/03/25
Self Imaging technique for refocusing an aerospace camera (EI CONFERENCE) 会议论文  OAI收割
ICO20: Optical Devices and Instruments, August 21, 2005 - August 26, 2005, Changchun, China
作者:  
Li W.;  Li W.;  Wang X.;  Wang X.;  Wang X.
收藏  |  浏览/下载:41/0  |  提交时间:2013/03/25
A novel auto-focusing technique using a self imaging approach is developed for an aerospace camera having large aperture and long focus. Its optical system consists of an emitting system  receiving system  and two penta-prisms. Emitting system has three parts: a light source  beamsplitter  and aim slit. The receiving system includes a field lens  two separate lenses  and CCD. Using two little penta-prisms instead of a large planar mirror makes the autofocus system simple and compact. CCD was used as photoelectric converting device. A defocused signal is acquired by measuring the change of the two slit self-images position imaged on the CCD. A simple and compact construction of the auto-focusing system was proposed. The algorithm to calculate the moving of the slit-self images position was analyzed in order to achieve subpixel position estimation. The results of the experiments show a 10m focusing precision. The system demonstrates high resolution  easy adjustment and high reliability.  
Study on LD-pumped Nd:YAG laser cutter (EI CONFERENCE) 会议论文  OAI收割
ICO20: Lasers and Laser Technologies, August 21, 2005 - August 26, 2005, Changchun, China
作者:  
Zhang G.;  Zhang G.;  Zhang G.;  Zhang J.;  Zhang J.
收藏  |  浏览/下载:29/0  |  提交时间:2013/03/25
The theory of laser cutter and the technology neck is analyzed. We can conclude that it is almost impossible to deal with the waste thick silicon wafers which are yielded in producing silicon wafers by conventional eroding or diamond cutting  when the cutting velocity equals 100mm/min  while it is also unperfected with ecumenical laser cutter without good beam quality or precise laseroptics system. It is represented that high average power and high repetition rate laser with good beam quality and precise laseroptics system are pivotal to obtain excellent cutting effect such as thick groove depth  double-layer 0.75mm thick silicon wafer can be penetrated.. The cross section is fine and the groove is narrow  rapid cutting speed  the cutting quality meets the expecting demand.  fine kerf section without considering the effect of technique. Considering laser medium thermal lens effect and thermal focal length changing with pumping power  using plano-convex high reflectivity mirror as the back cavity mirror to compensate the heat lens influence  a /4 waveplate to compensate heat -induced birefraction  utilize the Nd:YAG self- aperture effect  more than 50 W average power 1.064 um IR output is obtained with beam quality factor (M2) equals 3.19. Through the LD-Pumped Nd:YAG laser cutter we developed with short focus length negative spherical aberration focusing lens  double axis linear step motor positioning system  suitable beam expander multiplying factor  appropriate diameter of exit beam aperture  proper repetition rate  when the cutting velocity equals 400mm/min  0.75mm thick silicon wafer can be penetrated