Fine pointing of laser beams using laser arrays for applications to CubeSats

Abstract

A method of fine pointing of laser beams using laser arrays has been developed. The telescope system combines a lens system and a vertical cavity surface emitting laser/photodetector array. It does not use moving parts. In computer simulations, it is applied to CubeSats satellites that use body pointing. Body pointing was used by the Aerospace Corporation for CubeSats in LEO at 450 km in NASA’s Optical Communications and Sensors Demonstration (OCSD) program. Computer simulations of this fine pointing capability have been applied previously to CubeSats in the OCSD program. Computer simulations of this laser pointing are applied to CubeSats in LLO at 100 km. With more accurate pointing, a laser beam with smaller divergence can be used. For the case of the AeroCube-7B vehicle that was used in the OCSD program, computer simulations show, for example, that the divergence of the output beam can be reduced from ∼0.06 deg to 0.014 deg. For the proposed electro-optical system, reaction times to pointing changes and vibrations are on a nanosecond time scale, much faster than those for fine pointing systems that use moving parts, such as fast steering mirrors or that use quad-cell photodetectors to improve the body pointing of the CubeSat.