Investigation of Inverse Solutions for Tilting Orthogonal Double Prisms in Laser Pointing with Submicroradian Precision

Laser pointing unit using tilting orthogonal double prisms (TODP) opens up a promising avenue for fine pointing in free-space laser communication, which can steer the laser beam with a pointing precision upon submicroradian order. How to obtain accurate inverse solutions is a basic issue for TODP systems. In this paper, a lookup-table method combined with the binary search procedure is demonstrated, and an iterative method that converges to the inverse solution by gradually reducing the search region is also investigated. The simulation results show that both methods can reach the pointing precision of micrometer order (namely submicroradian order after unit conversion) at a pointing distance of 400 mm, which can well meet the requirement of high-accuracy laser beam pointing applications.