Optical beam steering in laser terminals for enhanced laser communication through component interaction evaluation

Optical beam steering is essential for maintaining line-of-sight (LOS) connections between communicating terminals, ensuring reliable Free Space Optical (FSO) communication. However, achieving a LOS connection is challenging due to disturbances such as vibrations from communication terminal and/or the host of the terminal, which can misalign the optical beam. The accuracy of the optical beam position sensor, the controller for the beam actuation unit, and the actuation units impact the beam steering system’s performance. While extensive research has emphasized the importance of fast-steering mirrors (FSMs) as actuators and quadrant detectors (QDs) as optical beam position sensors in beam steering systems, most of these studies have focused on analyzing FSMs and QDs in isolation. This paper proposes a method to design and evaluate the impact of these components concurrently. Specifically, it suggests a tuning procedure for the controller in the FSM closed feedback loop and models the QD sensor using experimental data. The QD model is then integrated into the FSM control loop. To validate the viability of this integrated approach, its results are compared to those obtained with an ideal sensor. Integrating the QD model into the FSM control loop slightly increases overshoot but a faster and more responsive control is attainable.