前照条件下LAMOST焦面板光纤单元定位精度检测系统设计
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摘要
大天区面积多目标光纤光谱望远镜(Large Sky Area Multi-object Optical Spectroscopic Telescope,LAMOST)是目前国际上口径最大、视场最宽、光谱获取率最高的大型施密特望远镜,通过借助并行可控式双回转光纤定位系统,其焦面系统上的4 000根光纤可以在数分钟内按预定天体坐标快速精确地对准各自观测目标并进行精调。望远镜观测时每一个光纤单元定位情况的好坏直接决定接收天体光谱的质量,然而目前针对光纤定位精度情况仅有的信息就是定位时光纤单元步进电机驱动情况的反馈,是一个内部信息,并不全面,无法给出每一个光纤单元的实际定位精度情况。因此需要搭建一个可用于LAMOST现场的检测系统,在望远镜观测间隙,在前置光源照明条件下,可以第一时间获取焦面板光纤单元定位图像,快速分析之后,检测出定位误差较大的光纤单元,由此决定进一步观测处理措施,以保证观测光谱的有效性和准确率。
The Large Sky Area Multi-Object Fiber Spectroscopic Telescope( LAMOST) is an innovative reflection Schmidt telescope. It is designed to have a spectrum acquisition rate as high as several tens of thousands of spectra per night. By using the technique of controllable double-revolving positioning of optical fibers,the LAMOST can reconfigure and fine adjust optical fibers to accurately match directions to objects in minutes. During an observation period,the positioning accuracy of an optical-fiber unit has a major impact on the quality of a spectrum acquired through the unit. Currently,the only retrievable real-time information for positioning accuracies of optical fibers is the feedback about conditions of the driving stepper motor. Such information is incomplete and indirect. It cannot reflect the actual position of an optical-fiber unit. We design a novel system to measure real-time optical-fiber positioning accuracies by taking into considerations the on-site environment of the LAMOST. During observaton intervals,the system records real-time images of positions of optical-fiber units on the LAMOST focal plane using front light sources. It quickly identifies optical-fiber units of relatively large positioning errors with certain analysis,allowing for appropriate adjustments in observation procedures. The system can be integrated into the existing observation and control systems. The system can provide complete and effective information about positions of optical-fiber units on the LAMOST focal plane. Based on information retrieved through the system observation assistants can properly adjust their observation strategies to ensure acquried spectra to be sufficiently accurate. Information provided by the system can also indicate the quality of the acquired spectra,which increases the efficiency of processing spectra.
The Large Sky Area Multi-Object Fiber Spectroscopic Telescope( LAMOST) is an innovative reflection Schmidt telescope. It is designed to have a spectrum acquisition rate as high as several tens of thousands of spectra per night. By using the technique of controllable double-revolving positioning of optical fibers,the LAMOST can reconfigure and fine adjust optical fibers to accurately match directions to objects in minutes. During an observation period,the positioning accuracy of an optical-fiber unit has a major impact on the quality of a spectrum acquired through the unit. Currently,the only retrievable real-time information for positioning accuracies of optical fibers is the feedback about conditions of the driving stepper motor. Such information is incomplete and indirect. It cannot reflect the actual position of an optical-fiber unit. We design a novel system to measure real-time optical-fiber positioning accuracies by taking into considerations the on-site environment of the LAMOST. During observaton intervals,the system records real-time images of positions of optical-fiber units on the LAMOST focal plane using front light sources. It quickly identifies optical-fiber units of relatively large positioning errors with certain analysis,allowing for appropriate adjustments in observation procedures. The system can be integrated into the existing observation and control systems. The system can provide complete and effective information about positions of optical-fiber units on the LAMOST focal plane. Based on information retrieved through the system observation assistants can properly adjust their observation strategies to ensure acquried spectra to be sufficiently accurate. Information provided by the system can also indicate the quality of the acquired spectra,which increases the efficiency of processing spectra.
引文
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[11]邹益民,汪渤.一种基于最小二乘的不完整椭圆拟合算法[J].仪器仪表学报,2006,27(7):808-812.Zou Yimin,Wang Bo.Fragmental ellipse fitting based on least square algorithm[J].Chinese Journal of Scientific Instrument,2006,27(7):808-812.
[2]邢晓正,胡红专,杜华生,等.用于LAMOST的并行可控式光纤定位系统[J].中国科学技术大学学报,1997,27(4):120-123.Xing Xiaozheng,Hu Hongzhuan,Du Huasheng,et al.A parallel controllable optical fiber positioning system for LAMOST[J].Journal of University of Science and Technology of China,1997,27(4):120-123.
[3]胡红专,邢晓正,李为民,等.双回转光纤定位单元装置[J].中国科学技术大学学报,2000,30(6):78-81.Hu Hongzhuan,Xing Xiaozheng,Li Weimin,et al.Double revolving optical fiber positioning unit device[J].Journal of University of Science and Technology of China,2000,30(6):78-81.
[4]中国科学技术大学焦面光纤定位研究组.LAMOST焦面光纤定位系统研制报告[R].2003.2.
[5]K Lau R,Hocken W C,Haight.Automatic laser tracking interferometer system for robot metrology[J].Precision Engineering,1986,8(1):3-8.
[6]Wendt.Development of test and calibration for automated theodolite system in production metrology[R].PTB Germany,1996.
[7]冯文濒.近景摄影测量[M].武汉:武汉大学出版社,2002.
[8]Tsai R Y.A versatile camera calibration technique for high-accuracy 3D machine vision metrology using off the shelf TV camera and lenses[J].IEEE Journal of Robotics and Automation,1987,RA 23(4):323-344.
[9]陈宝林.最优化理论与方法[M].北京:清华大学出版社,1989.
[10]滕勇,金熠,胡红专,等.单个CCD摄像机大视场测量方法[J].机械与电子,2006(12):20-23.Teng Yong,Jin Yi,Hu Hongzhuan,et al.Single CCD camera large view field measurement system[J].Machinery&Electronics,2006(12):20-23.
[11]邹益民,汪渤.一种基于最小二乘的不完整椭圆拟合算法[J].仪器仪表学报,2006,27(7):808-812.Zou Yimin,Wang Bo.Fragmental ellipse fitting based on least square algorithm[J].Chinese Journal of Scientific Instrument,2006,27(7):808-812.