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2010 CFHT Users Meeting
November 16-18, 2010
ASIAA Auditorium, Taipei, Taiwan

Poster Presentation

Image Quality and performance results of GLAO and OTCCD simulations for `IMAKA.

Author(s): Olivier Lai, Mark Chun, Jean Charles Cuillandre, David Andersen, John Pazder, Jean Pierre VĂ©ran, Laurent Jolissaint, Emmanuel Bertin, Derrick Salmon

Presenter: Olivier Lai (Canada France Hawaii Telescope)

The goal of `IMAKA is to produce images of FWHM of 0.3" at 700nm over a square degree. The characteristics of the turbulence of Mauna Kea, believed to be composed of a very thin ground layer with excellent free atmosphere seeing, allows very wide fields to be corrected by a Ground Layer Adaptive Optics (GLAO) system. The image is then limited by the free atmosphere seeing. This can be further improved by an OTCCD camera which can correct local image motion on isokinetic scales from residual high altitude tip-tilt.

Starting from a standard Mauna Kea profile (derived by M.Chun in the Gemini GLAO study), we have implemented a Monte Carlo simulation code that allows to compute the GLAO and OTCCD corrected PSF across very large fields. The code, instant_GLAO, allows to simulate quartile ground layer and free atmosphere turbulence, includes dome seeing and the primary figure as well as the option to include optical design (potentially chromatic) aberrations. The deformable mirror can be misconjugated or tilted with respect to the pupil to simulate all the problems associated with such a large Lagrange Invariant. Finally, the reconstructor can be a simple average (GLAO), a zonal and modal reconstructors and a tomographic reconstructor is currently being implemented. To ensure faster convergence, we make the assumption that the temporal error can be made small.

instant_GLAO's performance has been cross-checked with other simulation packages such as simul, yao, LAOS and PAOLA, and they all offer excellent agreement. instant_GLAO has been used to estimate the PSF used in the sensitivity simulations and computations and to study the effect of unevenly distributed GLAO and OTCCD stars on the image quality variations across a realistic (COSMOS) deep field. In this presentation, we will report on the simulation results demonstrating that from the input turbulence profile, it is possible to obtain median images of 0.3" at 700nm over the 1 degree field of view in a realistic system.

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