The identification and prediction of time-varying wavefront errors in adaptive optics (AO) systems promises fainter limiting guide star magnitudes and improved temporal bandwidth errors. In a new UCSC-LLNL collaboration, we aim to demonstrate the power of predictive Fourier controllers for AO in the laboratory and on-sky. We have used the Fourier Wind Identification technique to measure wind velocities at several telescopes, and now have demonstrated the identification of frozen flow turbulence with a translating phase screen on a laboratory test bench. Here, we present identification of the wind direction and velocity using telemetry data from a laboratory testbed simulating the ShaneAO system geometry. Our wind identification system uses a Fourier decomposition technique to identify the correlated movement of the atmosphere from WFS telemetry data, which are then used to construct a Kalman filter for real-time operation. We demonstrate the use of an LQG controller with the ShaneAO system architecture, and show that the effects of frozen flow turbulence can be easily identified in laboratory telemetry. We describe the adaptations made to the LQG controller to integrate it into the dual-DM architecture of the ShaneAO system, and demonstrate that these modifications produce stable and well-understood AO correction in the laboratory.

Date Published: 21 July 2014
PDF: 10 pages
Proc. SPIE 9148, Adaptive Optics Systems IV, 91481Z (21 July 2014); doi: 10.1117/12.2057194

Published in SPIE Proceedings Vol. 9148:
Adaptive Optics Systems IV
Enrico Marchetti; Laird M. Close; Jean-Pierre Véran, Editor(s)