Multiconjugate adaptive optics results from the laboratory for adaptive optics MCAO/MOAO testbed

Abstract

We report on the development of wavefront reconstruction and control algorithms for multiconjugate adaptive optics (MCAO) and the results of testing them in the laboratory under conditions that simulate an 8 meter class telescope. The University of California Observatories (UCO) Lick Observatory Laboratory for Adaptive Optics multiconjugate testbed allows us to test wide-field-of-view adaptive optics systems as they might be instantiated in the near future on giant telescopes. In particular, we have been investigating the performance of MCAO using five laser beacons for wavefront sensing and a minimum-variance algorithm for control of two conjugate deformable mirrors. We have demonstrated improved Strehl ratio and enlarged field-of-view performance when compared to conventional AO techniques. We have demonstrated improved MCAO performance with the implementation of a routine that minimizes the generalized isoplanatism when turbulent layers do not correspond to deformable mirror conjugate altitudes. Finally, we have demonstrated suitability of the system for closed loop operation when configured to feed back conditional mean estimates of wavefront residuals rather than the directly measured residuals. This technique has recently been referred to as the "pseudo-open-loop" control law in the literature.

A laboratory demonstration of an LQG technique for correcting frozen flow turbulence in adaptive optics systems

“…Our experiments are performed on a modified and optimized version of the UCSC Laboratory for Adaptive Optics (LAO) MCAO/MOAO testbed [13]. In the past, its utility and versatility has been shown by simulating MCAO and open-loop MOAO on a 30-m equivalent aperture telescope [14], demonstrating the positive effect of linearity calibrations to Shack-Hartmann wavefront sensors during open-loop MOAO operation on a 10-m telescope [15] and for developing wavefront reconstruction and control algorithms for MCAO on an 8-m class telescope [13]. Currently, we have reconfigured the testbed to match as closely as possible the new adaptive optics system on the Shane 3-m telescope at Lick Observatory (ShaneAO) [11] so that the transition from lab to a real system is as seamless as possible.…”

“…The ShaneAO system with the ShARCs Camera on the Shane 3-m telescope at Lick Observatory [11,12] provides an on-sky instrument. At the Lab for Adaptive Optics we have configured an adaptive optics test bench [13] to mimic the hardware and physical conditions for ShaneAO. These closely coupled systems allow us to test and develop techniques in a controlled lab before proceeding to the instrument on-sky for functional tests.…”

Integrated Laboratory Demonstrations of Multi-Object Adaptive Optics on a Simulated 10 Meter Telescope at Visible Wavelengths

“…The control algorithms for this testbench are discussed in more detail in prior publications (Ammons et al 2006(Ammons et al , 2007Laag et al 2008) and here summarized. No part of the reconstruction or control is matrix-based.…”

Open-loop shape control for continuous microelectromechanical system deformable mirror

“…For example, multiobject adaptive optics is an instrument concept that would allow highresolution imaging of a large number of faint objects across a wide field of view in an extremely large telescope. This concept would require controlling multiple DMs in an open loop because the DMs would modify the wavefront downstream of the wavefront sensor [1][2][3]. In microscopy, open-loop DM control has enabled new control approaches to nonlinear microscopy for high-resolution subsurface imaging.…”