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	Telescopes Alignment Using the Sharpness Function Method Based on Undersampled Images 期刊论文 OAI收割 IEEE Photonics Journal, 2019, 卷号: 11, 期号: 1 作者: Li, Min; Liu, Xin; Zhang, Ang; Xian, Hao \| 收藏 \| 浏览/下载：13/0 \| 提交时间：2021/05/06 Telescope alignment SPGD algorithm relative RMS errors under-sampled images
	Telescope images segmentation with OTSU method 会议论文 OAI收割 Chengdu, PEOPLES R CHINAChengdu, PEOPLES R CHINA, JUN 26-29, 2018JUN 26-29, 2018 作者: Li, Min; Zhang, Ang; Xian, Hao \| 收藏 \| 浏览/下载：24/0 \| 提交时间：2019/08/23 telescope images image segmentation OTSU method anti-noise capability
	Astronomical image restoration through atmosphere turbulence by lucky imaging (EI CONFERENCE) 会议论文 OAI收割 3rd International Conference on Digital Image Processing, ICDIP 2011, April 15, 2011 - April 17, 2011, Chengdu, China 作者: Zhao J.; Wang J.; Zhang S. 收藏 \| 浏览/下载：28/0 \| 提交时间：2013/03/25 In this paper we develop a lucky imaging system to restore astronomical images through atmosphere turbulence. Our system takes very short exposures on the order of the atmospheric coherence time. The rapidly changing turbulence leads to a very variable point spread function (PSF) and the variability of the PSF leads to some frames having better quality than the rest. Only the best frames are selected aligned and co-added to give a final image with much improved angular resolution. Our system mainly consists of five parts: preprocessing frame selection image registration image reconstruction and image enhancement. Our lucky imaging system has been successfully applied to restore the astronomical images taken by a 1.23m telescope. We have got clear images of moon surface and Jupiter and our system can be demonstrated to greatly improve the imaging resolution through atmospheric turbulence. 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).
	Far-field focusing of laser beam based on digital image processing techniques (EI CONFERENCE) 会议论文 OAI收割 Optoelectronic Imaging and Multimedia Technology, October 18, 2010 - October 20, 2010, Beijing, China 作者: Zhao S.; Tian Y.-Z.; Liu L.-S.; Guo J.; Zhang H.-Y. 收藏 \| 浏览/下载：28/0 \| 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.
	Imaging analysis of a novel compound diffractive telescope system (EI CONFERENCE) 会议论文 OAI收割 Optical Manufacturing and Testing VIII, August 4, 2009 - August 5, 2009, San Diego, CA, United states 作者: Liu H.; Liu Y.; Liu Y.; Liu Y.; Zhang H. 收藏 \| 浏览/下载：34/0 \| 提交时间：2013/03/25 The main feature of the compound diffractive telescope is the combination of diffractive optics with compound structure arranged eyepieces. In this paper a design of the compound diffractive telescope is firstly introduced and a 4.2 FOV is obtained with one primary lens and twenty-one eyepieces. Secondly image characteristic of different channels is analyzed with the design wavelength in ASAP and one modified phase function model of diffractive optical element is introduced to analyze the MTF curves for 0 FOV which provides a more accurate prediction of the performance of the system. Then the system is tested by the star image test and the diffraction limit images are got within 2 FOV. And finally two pictures taken from the adjacent FOV proved to be able to be spliced together. All the results above demonstrate that a good performance of the compound diffractive telescope. 2009 SPIE.
	Resolution performance of extreme ultraviolet telescope (EI CONFERENCE) 会议论文 OAI收割 4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, November 19, 2008 - November 21, 2008, Chengdu, China 作者: Yang L.; Chen B.; Chen B.; Liang J.-Q.; Ni Q.-L. 收藏 \| 浏览/下载：30/0 \| 提交时间：2013/03/25 Extreme Ultraviolet Telescope (EUT) will image solar corona in four EUV narrow bandpasses defined by multilayered coatings deposited on normal incidence optics. In order to make sure it will get sub-arcsecond angular resolution in the mission we have to test its resolution performance on ground. The EUT is aligned by Zygo interferometer first and a global wavefront error of 0.152 peak to valley is obtained ( = 632.8nm ). Because of the difficulty of angular resolution test for EUT at its operating wavelengths we test its optical performance at visible and UV band. The method is to place the resolution test-target on the focal plane of collimator and illuminate the target by visible and UV light espectively then the collimated light will go through EUT and image at focal plane on CCD. By analysis of the images obtained in experiments we conclude that the angular resolution of EUT is 1.22 at visible light ( = 570nm ) which is very close to diffraction limit (1.20) and according to these results we estimate that the operational wavelength resolution is better than 0.32 meets design requirements. While for UV light the angular resolution is 1.53 that is different from diffraction limit (0.53) the error comes mainly from large pixel of EUV camera. 2009 SPIE.