Adaptive reconstructors for adaptive optics

This paper concerns a class of adaptive optics problems in which phase distortions due to atmospheric turbulence are corrected by adaptive wavefront reconstruction with a deformable mirror-i.e., the control loop that drives the mirror adapts in real time to time-varying atmospheric conditions, as opposed to the linear time-invariant control loops used in conventional "adaptive optics." The basic problem is posed here as an adaptive disturbance rejection problem with many channels. The solution given here is to augment a linear time-invariant feedback control loop with an adaptive feedforward control loop based on a multichannel adaptive lattice filter. Simulation results are presented for a one-meter telescope with both single-layer and two-layer atmospheric turbulence profiles. These results demonstrate the significant improvement in imaging resolution produced by the adaptive control loop.