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	Auto-focusing evaluation functions in digital image system (EI CONFERENCE) 会议论文 OAI收割 2010 3rd International Conference on Advanced Computer Theory and Engineering, ICACTE 2010, August 20, 2010 - August 22, 2010, Chengdu, China 作者: Gao Y. 收藏 \| 浏览/下载：19/0 \| 提交时间：2013/03/25 Evaluation function is an important item to measure the quality of images in auto-focusing systems. This paper introduces four categories of evaluation functions which are respectively based on gradient correlation statistics and transform. These functions formally differ from each other and their performances are not consistent when dealing with different images. The same function also performs different when the processed images have different characteristics. Five commonly used functions from the four categories are verified and compared under different circumstances in order to validate their performances. The result provides references for variety of selections in the practical application. 2010 IEEE.
	Application of precision harmonic gear drive in focusing mechanism of space camera (EI CONFERENCE) 会议论文 OAI收割 5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Smart Structures and Materials in Manufacturing and Testing, April 26, 2010 - April 29, 2010, Dalian, China 作者: Zhang X.; Zhang X.; Zhang X. 收藏 \| 浏览/下载：26/0 \| 提交时间：2013/03/25 A kind of precision harmonic gear drive in the focusing mechanism of space camera is studied which adopt external meshing complex wave transmission mode. Wave generator is combined with an elliptic cam and a flexible bearing around it. Flexspline is a structure of single wave with the same teeth. The output shaft is supported by a single cross-roller bearing. Ball screws connected the output shaft translate the rotational motion to the linear motion and drive the focusing mirror repeated moving along the linear guide. The output rigid wheel is connected with absolute encoder to detect displacement of focusing movement. It has the characteristics of big transmission ratio high precision compact structure high efficiency and smooth running etc. According to the practical application of this harmonic gear drive in the space camera the location relationship between the displacement of focusing structure and the focal plane movement is derived and the system error is analyzed its accuracy is tested with the open-loop control method. Experimental results show that transmission ratio of the instrument is 1:70 repeated positional accuracy is 2m which meet the requirements for use. 2010 SPIE.
	Design of video auto focusing based on image processing (EI CONFERENCE) 会议论文 OAI收割 ICO20: Optical Information Processing, August 21, 2005 - August 26, 2005, Changchun, China Meng B.; Zhu M.; Cai C.-J. 收藏 \| 浏览/下载：20/0 \| 提交时间：2013/03/25 In order to realize the auto focusing technique based on digital image processing a video image processing system is designed by using high-performance digital signal processor TMS320VC5509 as the core field programmable gate array FPGA for preprocessing of image. At the same time it is proposed to use vector norm sum of image gray gradient as evaluation functions of digital image. It has the characteristics of good unbiasedness powerful unimodality etc. and can be applied to evaluation of defocusing. The hardware composition of the theory behind the auto focusing system and the application of the evaluation function are discussed in details.
	High-power VCSELs single devices aid 2-D arrays (EI CONFERENCE) 会议论文 OAI收割 ICO20: Lasers and Laser Technologies, August 21, 2005 - August 26, 2005, Changchun, China 作者: Liu Y.; Wang L.; Wang L.; Wang L.; Liu Y. 收藏 \| 浏览/下载：13/0 \| 提交时间：2013/03/25 The high power bottom-emitting vertical-cavity surface-emitting lasers (VCSELs) and laser arrays emitting at 980 nm are reported. Extensive investigations on size scaling behavior of thermal properties of single devices show limits of attainable output characteristics. The maximum continuous wave (CW) output power at room temperature of single devices with aperture size up to 500 m is as high as 1.95 W. The key characteristics such as maximum output power wavelength and thermal resistance are discussed. The bottom-emitting arrays of 16 elements and 200 m aperture size of individual elements show output power of CW 1.35 W at room temperature. The far-field angle is below 17 for all driving current which is very favorable for focusing or collmating optics.
	Optimization of the focusing characteristics of Fresnel zone plates fabricated with a femtosecond laser 期刊论文 OAI收割 JOURNAL OF MODERN OPTICS 作者: Zhou, Fang; Sun, Xiaoyan; Zhong, Hongmin; Duan, Lian; Hu, Youwang \| 收藏 \| 浏览/下载：17/0 \| 提交时间：2021/02/22 Micro-optical components Fresnel zone plates focusing characteristics femtosecond laser fiber