Airborne laser communication systems often require a control system for each transceiver providing pointing control of a reference line of sight aboard a stabilized platform. These control systems often apply target in the loop techniques using a fast steering mirror (FSM) that reflects the incoming beacon image towards a 2 axis optical sensor. Sensor measurements and processing provide estimates of the beacon image centroid in a feedback control system with the FSM to center the image against disturbing influences. These disturbances appear as exogenous inputs in the control loop and are derived from both 1) atmospheric turbulence, which distorts the shape and direction of the beacon image, and 2) residual vibrations, which originate in the aircraft structure, and are attenuated by the stabilized platform. Models for both turbulence and structurally induced vibrations are described and applied in simulation with an FSM control system for an air-to-air laser communications system developed by Trex Enterprises for the Air Force Research Laboratory, WPAFB. Results from the simulation estimate obtainable bandwidth, stability margins and expected disturbance reduction. Simulation results are compared to actual performance measurements.

Date Published: 18 October 2004
PDF: 12 pages
Proc. SPIE 5552, Target-in-the-Loop: Atmospheric Tracking, Imaging, and Compensation, (18 October 2004); doi: 10.1117/12.555718

Published in SPIE Proceedings Vol. 5552:
Target-in-the-Loop: Atmospheric Tracking, Imaging, and Compensation
Michael T. Valley; Mikhail A. Vorontsov, Editor(s)