Beam pointing and coarse tracking characteristics of Tip-Tilt mirror type laser communication terminal

To realize the coarse tracking of laser communication terminal (LCT) with a single plane mirror （Tip-Tilt mirror type）and two orthogonal rotation axes, a normal vector solving algorithm for beam pointing was proposed. The coarse tracking algorithm of this type LCT was given. By using vector reflection law and matrix rotation transformation, a theoretical derivation of the tip-tilt mirror was carried out to get the analytical solution of the beam pointing model and tracking model. The effects of different installation methods on the beam pointing and distortion were discussed. The model was researched on modeling simulation and experiment respectively. The results show that the accuracy of the beam pointing model and the coarse tracking model are better than 3 µrad. The developed LCT has a coarse tracking accuracy better than 15.5 µrad (3σ), and the RMS error is better than 10.5 µrad. It meets the high-precision coarse tracking requirements of the LCT. The work has reference significance for beam pointing analysis of the Tip-Tilt mirror type scanning system and laser terminal coarse tracking.