Key Challenges and Results in the Design of Cubesat Laser Terminals, Optical Heads and Coarse Pointing Assemblies

The anticipated capacity benefit of optical satellite communications has triggered a cascade of technology developments. In this paper, we present three such technologies, namely; i). A cube satellite laser terminal (CubeCAT), ii). A lower Earth orbit satellite optical head (LEOCAT) and iii). A calibration and verification test bench for coarse pointing assemblies, named pointing test bench (PTB). For these technologies, pointing stability and accuracy are central challenges. For i) and ii), we discuss anticipated effects of the thermal and mechanical disturbances that threaten the optical alignment of the system. We furthermore explain the mitigation of these effects through the system design so that a high optical performance can be maintained. For iii), we discuss the mechanical design challenges, in combination with modelling and calibration procedures for the system. Effective dealing with the three of them in turn enables highly accurate mirror orientation and rotation. Design specifications and current status are presented for each system.