Steering mirror system with closed-loop feedback for free-space optical communication terminals

Pointing, Acquisition, and Tracking (PAT) are critical aspects of both uplink and downlink Free Space Optical (FSO) communications systems, ensuring precise targeting of the optical signal from the transmitter to the receiver. PAT systems provide steering and tracking capabilities in order to establish and maintain an optical link, compensating for the relative satellite motion, atmospheric turbulence, vibration and jitter. <br/> <br/> A novel method for achieving closed loop control between the steering mirrors of a dual channel free space optical communications terminal is presented. By modifying an off-the-shelf open loop stick-slip actuator, the control system achieves a pointing resolution of 0.002° with under a 15% increase in mass, resulting in a light weight solution suitable for small satellites.