A correction method of encoder bias in satellite laser ranging system

In a satellite laser ranging telescope system,well-aligned encoders of the elevation and azimuth axes are essential for tracking objects.However,it is very difficult and time-consuming to correct the bias between the absolute-position indices of the encoders and the astronomical coordinates,especially in the absence of a finder scope for our system.To solve this problem,a method is presented based on the phenomenon that all stars move anti-clockwise around Polaris in the northern hemisphere.Tests of the proposed adjustment procedure in a satellite laser ranging(SLR)system demonstrated the effectiveness and the time saved by using the approach,which greatly facilitates the optimization of a tracking system.