Distributed modal command for a two-deformable-mirror adaptive optics system

Abstract

The design of future single-altitude conjugated adaptive optics (AO) systems may include at least two deformable mirrors (DMs) instead of one as in the current AO system. Each DM will have to correct for a specific spatial frequency range. A method is presented to derive a DM modal basis based on the influence functions of the DM. The modal bases are derived such that they are orthogonal to a given set of modes that restrict the DM correction to a spatial frequency domain. The modal bases have been tested on the woofer-tweeter test bench at the University of Victoria. It has been shown that the rms amplitude of the woofer DM and tweeter DM stroke can be reduced by factors of 3 and 9, respectively, when making the transition from a zonal-driven closed loop to a modal-driven closed loop with the same performance in both cases.

Status of the PALM-3000 high-order adaptive optics system

“…An independent loop operating with a I-frame delay then computes the projection of the HOOM surface shape onto the LOOM actuators, and offloads these low-order modes. An alternative control scheme (mode 2) is planned for the other pupil sampling modes, in which a reconstructor matrix computed following the prescription of eon an et al 22 splits commands to the two deformable mirrors based on spatial frequency. Approximately 3000 modes orthogonal to the LOOM actuator influence functions with controlled with the HOOM.…”

MEMS adaptive optics for the Gemini Planet Imager: control methods and validation

“…Conan et al are studying spatial WooferTweeter with a testbed. 13 Their setup is significantly different than ours, in that their mirrors have similar ratios of pupil diameter D to actuator spacing d of D/d = 7 for the Woofer and D/d = 9 for the Tweeter, while for GPI we have 8 for the Woofer and 44 for the Tweeter. They are also are not using a Fourier-mode wavefront control method.…”

Correction of active space telescope mirror using woofer-tweeter adaptive optics

“…[2][3][4] These atmospheric compensation systems require high bandwidth and large stroke to compensate for rapidly changing atmospheric turbulence. The proposed dual deformable mirror space telescope configuration corrects static residual errors and low bandwidth disturbances caused by the thermally dynamic environment.…”