Large Scale, Visual Measurement Techniques

The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) project is one of the five National Major Scientific Projects undertaken by the Chinese Academy of Science. LAMOST is a quasi-meridian reflecting Schmidt telescope laid down on the ground with its optical axis fixed in the meridian plane.In the fiber positioning system of LAMOST, it is one of the most pivotal tasks to detect the position of the fibers' end . In order to verify the precision of fibers' position, the measurement system is needed to measure the geometrical coordinates of fibers' end.During the development of the fiber positioning unit, the measurement system was designed and realized. While fibers' positions are detected, the traditional detection method, such as coordinate measuring machine and universal tool maker's microscope, can not fill the detection demands of high precision, non-contact and fast detection. According to the parallel controllable fiber positioning system which is creatively designed by Xing Xiaozheng, Professor of Precision Machinery and Precision Instrumentation of University of Science and Technology of China, Prof. Xing designed the vision measurement system based on area scan CCD camera and applied it to the non-contact and fast detection of fibers' position of positioning units. The measurement project had been applied to the Medium-term system of LAMOST successfully, which is smoothly approved by Experts Group of project headquarters of LAMOST at November, 2003.Based on the measurement system of the fiber positioning medium-term system, aiming at the ongoing small focal plane system, we proposed the calibration method with differential coordinates on several discrete calibration boards and applied it to the camera calibration in the vision measurement system with wide field of view for the small focal plane system of LAMOST. At August, 2006, the differential calibration method of the vision measurement system with wide field of view was checked by the of project headquarters of LAMOST. The differential calibration method is approbated by the project headquarters of LAMOST.The author is responsible for the detection task of fibers position all along as one of main members of research group of fiber positioning system of LAMOST and has mainly completed the following work:1. The measurement system of fibers position based on area scan CCD camera for medium-term system of LAMOST was realized firstly. The detection method of fibers' position based on characteristic points was studied, and the main factors that affect measurement stability were analyzed.2. The dissertation studied the camera calibration method using the integral calibration board. All kinds of systematical error, such as the optical aberration of the camera, were fitted by the quadratic curved surface through the measurement of the calibration board. The transformational relationship between the coordinates of object plane and the coordinates of image surface was established directly in order to realize the camera calibration with high precision. In the calibration method using the integral calibration board, one calibration board whose size is similar to the measured object was used to realize the calibration. The dissertation discussed the dimension factor of the calibration board under a certain field of view. The camera can be calibrated by a calibration board whose size is a little smaller than the object plane, but the board can't be much smaller than the object plane. When the dimension...