EDP Sciences
Free access
Volume 400, Number 3, March IV 2003
Page(s) 1199 - 1207
Section Physical and chemical processes
DOI http://dx.doi.org/10.1051/0004-6361:20030022

A&A 400, 1199-1207 (2003)
DOI: 10.1051/0004-6361:20030022

Tilt anisoplanatism in laser-guide-star-based multiconjugate adaptive optics

Reconstruction of the long exposure point spread function from control loop data
R. C. Flicker1, 2, F. J. Rigaut2 and B. L. Ellerbroek2

1  Lund Observatory, Box 43, 22100 Lund, Sweden
2  Gemini Observatory, 670 N. A'Ohoku Pl., Hilo HI-96720, USA

(Received 22 August 2002 / Accepted 6 January 2003 )

A method is presented for estimating the long exposure point spread function (PSF) degradation due to tilt anisoplanatism in a laser-guide-star-based multiconjugate adaptive optics systems from control loop data. The algorithm is tested in numerical Monte Carlo simulations of the separately driven low-order null-mode system, and is shown to be robust and accurate with less than 10% relative error in both  H and K bands down to a natural guide star (NGS) magnitude of mR=21, for a symmetric asterism with three NGS on a 30 arcsec radius. The H band limiting magnitude of the null-mode system due to NGS signal-to-noise ratio and servo-lag was estimated previously to mR=19. At this magnitude, the relative errors in the reconstructed PSF and Strehl are here found to be less than 5% and 1%, suggesting that the PSF retrieval algorithm will be applicable and reliable for the full range of operating conditions of the null-mode system.

Key words: Instrumentation -- adaptive optics -- methods -- statistical

Offprint request: R. C. Flicker, ralf@astro.lu.se

© ESO 2003