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浏览/检索结果: 共3条，第1-3条 帮助 限定条件 发表日期：2005     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 Self Imaging technique for refocusing an aerospace camera (EI CONFERENCE) 会议论文 ICO20: Optical Devices and Instruments, August 21, 2005 - August 26, 2005, Changchun, China Li Z.; Wang X.; Li W.; Kuang H.; Han C. 收藏  |  浏览/下载：25/0  |  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.   Research on LD-Pumped dual wavelength Nd:YAG Laser with high beam quality for machining (EI CONFERENCE) 会议论文 ICO20: Lasers and Laser Technologies, August 21, 2005 - August 26, 2005, Changchun, China Cui J.; Fan Z.; Zhao C.; Zhang J.; Niu G.; Shi Z.; Pei B.; Zhang G.; Xue Y. 收藏  |  浏览/下载：24/0  |  提交时间：2013/03/25 Considering laser medium thermal lens effect and thermal focal length changes with pumping power  conventionally  lasers are designed to operate in the middle of thermal stable zones  where the fundamental mode size is insensitive to thermal perturbation  while this method seems impossible when large fundamental mode size is required. Through self-select mode cavity  lasers are designed to work at the border of stable zone instead  where large fundamental mode size in gain media can be reached. With increase of pumping power and self-aperture mode-selective effect  mode size would grow up automatically to a certain value suitable for monomode resonance. With double 180 W pump modules  acoustic Q-switch and LBO external frequency-doubled  over 28 W which M2 equals 4.5 quasi-CW output green laser and 52W 1.064 um IR output is obtained simultaneity. With the insertion or not of the harmonic separator by footswitch  high beam quality green  IR  and green IR lasers are obtained conveniently.   The geometric distortions correction of uncooled large-sized relative aperture infrared imaging system (EI CONFERENCE) 会议论文 Infrared Components and their Applications, November 8, 2004 - November 11, 2004, Beijing, China Fan X.; Sun Q.; Lu Z. 收藏  |  浏览/下载：14/0  |  提交时间：2013/03/25 The geometric distortion of infrared image  which was created by the large-sized relative aperture optical system. It could be corrected by the digital image processing technology. The magnitude of distortion would be enlarged quickly with the enlargement of relative aperture. Though the distortion could not impact on the articulation of the image  it would affect geometric location precision of the image directly. In this paper  the distortion correction of uncooled large-sized relative aperture infrared imaging system was discussed and the mathematical model of distortion correction was established. A algorithm of digital image processing was presented and applied based on control points by combining polynomial warping and space variant linear image interpolation. The method of polynomial warping was used to establish the locality relationship between the original image and the distortion ones. The space-variant linear image interpolation provided an efficient way to rebuild the frame of images. The computational costs of the proposed approach are very little and the precision is almost as high as the method of bicubic interpolation when compared to those of state-of-the-art nonlinear interpolation operators.