Study on position error of fiber positioning measurement system for LAMOST - art. no. 627113

An investigation on measuring precision of the measurement system is carried on, which is applied to optical fiber positioning system for LAMOST. In the fiber positioning system, geometrical coordinates of fibers need to be measured in order to verify the precision of fiber positioning and it is one of the most pivotal problems. The measurement system consists of an area CCD sensor, an image acquisition card, a lens and a computer. Temperature, vibration, lens aberration and CCD itself will probably cause measuring error. As fiber positioning is a dynamic process and fibers are reversing, this will make additional error. The paper focuses on analyzing the influence to measuring precision which is made by different status of fibers. The fibers are stuck to keep the relative positions steady which can rotate around the same point. The distances between fibers are measured under different experimental conditions. Then the influence of fibers' status can be obtained from the change of distances. Influence to position error made by different factors is analyzed according to the theory and experiments. Position error would be decreased by changing a lens aperture setting and polishing fibers.