Stabilization of laser beam position based on a closed-loop fast steering mirror system

This article is mainly focused on a method for stabilizing the position of an incident laser beam position by using a closed-loop fast steering mirror system. According to the input and output data, a model for the fast steering mirror system is established, which is utilized for the closed-loop controller. In the experiment, the spot centroid position, which is obtained by means of a position sensitive detector, is used as a signal for modeling and closed loop control. Because of the difference between the levels of atmospheric turbulence over water and over rock, the effects of the fast steering mirror system for the two cases may also differ. Therefore, experiments of laser beam stabilization have been carried out in these two different environments. The results show that the spot jitter is stronger when the laser is transmitted over rock, compared to transmission over water, and that spot jitter below 25 Hz can be restricted by closed-loop control in both environments.