Adaptive Laser Compensation for Aero-Optics and Atmospheric Disturbances

bandwidth of the classical AO control. It is shown that the residual phase variance with classical AO control, when normalized to the open-loop, scales as (fA/f3dB) , where is an arbitrary power and fA is a characteristic frequency of the aero-optical disturbance determined from a linear fit of the compensation data with increasing bandwidth. AO system latency degrades performance, especially with high-bandwidth control. When operating at a fixed but modest sampling frequency with appreciable latency, AO compensation performance can be significantly enhanced by application of an adaptive control augmentation based on lattice filtering of the residual wavefront sensor gradients, as was implemented in the wave-optics simulations. A classical controller operating at 200 Hz bandwidth with > 400 µsec latency has a limited ability to compensate the aero-optical and free-stream disturbances. By application of the adaptive feed-forward control, laser peak irradiance is shown to increase by a factor of 2.5 or more compared to classical AO feedback control.