Running-in Testing And Error Study For Optical Fiber Positioning Unit Of LAMOST

The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) project ,one of the National Major Scientific Projects undertaken by the Chinese Academy of Science,is a quasi-meridian reflecting Schmidt telescope with its optical axis fixed in the meridian plane. According to the holistic design of LAMOST, 4,000 optical fiber positioning units which are fixed in 1.75 meter spherical crown focal panel are required to aim at their observational targets quickly and precise, in order to obtain 4,000 stellar image targets simultaneously, and their positioning precision are required less than 40 micrometer. Each fiber and each control unit make up of an optical fiber positioning unit. Control unit is designed as double revolving style, including a central revolving axle and a bias revolving axle, both of which have equal revolving radius. The two revolving axles are driven by two stepper motors. Central revolving axle can move at the range of 0～360°,and bias revolving axle 0～180°,implementing precise positioning at any place of the entire circle area of diameter 35 millimeter.The thesis mainly enclose the core of precision, analyse all kinds of factors affected precision, combine fact situation and condition in existence, bring forward some testing methods correlated to errors,study correlated arithmetic of data handling and data analysis, have new positioning units running-in tested in order to verify their precision requirement. We mainly discuss testing methods, software development of data handling arithmetic, error analysis etc. The accomplished tasks are as following:1,Building up testing platform of optical fiber positioning unit; Having more than 4,000 optical fiber positioning units running-in tested, mainly including repeat positioning standard uncertainty testing, calibration, angle error testing and random point positioning testing; computing precision of optical fiber positioning unit.2,Studying testing data handling arithmetic to analyse and handle testing data; Developing data handling and analysing software in MATLAB and VC++; establishing optical fiber positioning unit acceptance file by using HTML language3,Studying all kinds of errors of system, having a further study in property, appearance orderliness and causation of coming into being, founding mathematical model, fitting and optimizing experimental data, using affine transformation model to have translation,rotation and scaling, eliminated the shaky image and improved precision of measurement effectively.