The Determination of the Parameters of Axial Collimator

It is explained that even if the circularness of the pivot of one meridian circle were controlled within ±0.2μm, there should be an error of ±0."04 for the stellar passing hour, and this circularness could not be kept after long wear and tear. The LLMC (Lower Latitude Meridian Circle)relaxes the precision requirements for the pivot.One axial collimator is setted to determine the influence of the circularness of the pivot and the thermal deformation of the forked arms, i.e., the two perpendicular groups of slits lig hted from rear on the focal plane of the collimator form their images on the two pieces of Reticon after reflection on one self-collimation plane mirror in the cavity of the ho rizontal axis, thus the determination of these errors can be made.At last, the method to determine the scale of Reticon is developed.