Vibration noise control in laser satellite communication

Laser satellite communication has become especially attractive in recent years. Because the laser beam width is narrower than in the RF or microwave range, the transmitted optical power may be significantly reduced. This leads to development of miniature communication systems with extremely low power consumption. On the other hand, the laser communication channel is very sensitive to vibrations of the Optical platform. These vibrations cause angular noise in laser beam pointing, comparable to the laser beam width. As result, a significant portion of the optical power between transmitter and receiver is lost and the bit error rate is increased. Consequently, vibration noise control is a critical problem in laser satellite communication. The direction of the laser beam is corrected with a fast steering mirror (FSM). In this paper are presented two approaches for the FSM control. One is the feedback control that uses an LQG algorithm. The second is the direct feed-forward control when vibration noise is measured by three orthogonal accelerometers and drives directly the FSM. The performances of each approach are evaluated using MATLAB simulations.