High-Precision and Large-Range Deflection of Light Beam with Fast Steering Mirrors

Fast steering mirrors (FSMs) offer a potential alternative for large-range deflection of light beams. However, for a large-stroke FSM, its pointing precision is unacceptably deteriorated due to the actuator non-uniformity, mechanical axis coupling, and the coupling of line-of-sight (LOS) kinematics. This Letter proposes a comprehensive beam-pointing algorithm by decoupling the LOS kinematic model and establishing a two-dimensional correction mapping to compensate for the non-uniformity and mechanical coupling. Moreover, the incident angle is calibrated by a non-contact method to construct the LOS kinematic model accurately. The experimental results proved that the beam-pointing accuracy can achieve a sub-milliradian level within the square field of regard (FOR) of ±25° horizontally and ±14° vertically. A pointing error of 0.87 mrad can be guaranteed within the horizontal range of -30° to 36° and the vertical range of ±24°. Therefore, the proposed method can achieve high-precision beam pointing in a large FOR and contributes to the miniaturization of optical systems.