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Proceedings Paper

Performance evaluation of a SCAO system for a 42-m telescope using the pyramid wavefront sensor
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Paper Abstract

We perform simulations of a single-conjugated adaptive optics (SCAO) system for an E-ELT-like telescope using a pyramid wavefront sensor (PWFS) and an on-axis NGS. The advantage of this WFS has already been demonstrated, being currently preferred in many AO systems where high signal sensitivity is critical. The main objective of this work is to evaluate the performance of such SCAO system under different control parameters (loop gain, modulation, truncated SVD mode), sensing wavelengths, atmospheric coherence scales and NGS magnitudes. Always adopting K as the science band, we have verified that the overall performance tends to be poorer as the sensing wavelength becomes shorter. The loop gain optimal range is dependent on the SVD truncation threshold used to build the command matrix, and a non-modulated PWFS produces in general poorer results when compared to modulated cases, being this especially true for the R- sensing band. The default atmospheric model adopted was a von Karman with r0=0.13m (at 500nm) and outer scale of 25m, but poorer and better seeing conditions have also been tested. The long-exposure Strehls are better in larger modulations. The telescope pupil has a central obstruction of 28% but no spiders were included. We also show results for the incidence of different photon fluxes at the PWFS detector.

Paper Details

Date Published: 14 July 2010
PDF: 9 pages
Proc. SPIE 7736, Adaptive Optics Systems II, 773648 (14 July 2010); doi: 10.1117/12.857111
Show Author Affiliations
Aurea Garcia-Rissmann, Steward Observatory, The Univ. of Arizona (United States)
Miska Le Louarn, European Organisation for Astronomical Research in the Southern Hemisphere (Germany)

Published in SPIE Proceedings Vol. 7736:
Adaptive Optics Systems II
Brent L. Ellerbroek; Michael Hart; Norbert Hubin; Peter L. Wizinowich, Editor(s)

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