The Pointing Variation of the Optical Axis in the LLMC

The pointing variation of the optical axis in the LLMC is introduced in this paper.It is pointed out that the variation is unable to simulate by the modified formula used in traditional meridian circles.Phenomena from two or three times of reflections of the autocollimation reflected light and corresponding processing methods are described.The defects in the mechanical design for the detection system and their improvement are presented.