The HIA MCAO laboratory bench
Jean-Pierre Véran (1), Dave Andersen (1), Carlos Correia (1), Glen Herriot (1), Jeff Goodwill (1), John Pazder (1), Olivier Lardière (2)
(1) Herzberg Institute of Astrophysics, National Research Council, Victoria, BC, Canada (2) University of Victoria, Victoria BC, Canada
In this paper, we present our current design of an MCAO laboratory bench to support the development of NFIRAOS, the first light MCAO facility for the TMT. This MCAO bench will build on the experience of the existing LGS WFS bench at University of Victoria, which uses a focus ramp induced by a deformable mirror (DM) and source modulation during WFS integration to produce Shack-Hartmann spots with the proper radial profile. The bench will implement a closed-loop MCAO system, with two magnetic DMs, four LGS Shack-Hartmann WFSs, two NGS T/T WFS, one NGS T/T/F WFS and one higher order Truth WFS, making up a scaled down version of NFIRAOS. Turbulence on the bench will be induced by the DMs and by two additional synthetic turbulence plates. The bench will be driven by software in Matlab, at a minimum frame-rate of 1Hz, up to 15Hz.
The goals of this bench are to anchor the NFIRAOS end-to-end simulation tools; to exercise real-time LGS tomographic AO in a variety of well controlled conditions, such as faint and poorly corrected NGSs, non-uniformities in the sodium layer and field dependant Non-Common-Path Aberrations (NCPAs); develop and demonstrate calibration procedures, such PSF reconstruction and tomographic reconstruction and correction of field dependant NCPAs; and to validate optimization methods that operates at 10+ second time scales, which is not tractable in a numerical simulation, such as matched filter update and Cn2 estimation using a SLODAR method.