NFIRAOS: TMT's facility adaptive optics system

Glen Herriot; David Andersen; Jennifer Atwood; Corinne Boyer; Annie Beauvillier; Peter Byrnes; Rod Conan; Brent Ellerbroek; Joeleff Fitzsimmons; Luc Gilles; Paul Hickson; Alexis Hill; Kate Jackson; Olivier Lardière; John Pazder; Thomas Pfrommer; Vlad Reshetov; Scott Roberts; Jean-Pierre Véran; Lianqi Wang; Ivan Wevers

doi:10.1117/12.857662

12 July 2010 NFIRAOS: TMT's facility adaptive optics system

Glen Herriot, David Andersen, Jennifer Atwood, Corinne Boyer, Annie Beauvillier, Peter Byrnes, Rod Conan, Brent Ellerbroek, Joeleff Fitzsimmons, Luc Gilles, Paul Hickson, Alexis Hill, Kate Jackson, Olivier Lardière, John Pazder, Thomas Pfrommer, Vlad Reshetov, Scott Roberts, Jean-Pierre Véran, Lianqi Wang, Ivan Wevers

Author Affiliations +

Proceedings Volume 7736, Adaptive Optics Systems II; 77360B (2010) https://doi.org/10.1117/12.857662
Event: SPIE Astronomical Telescopes + Instrumentation, 2010, San Diego, California, United States

Abstract

NFIRAOS, the TMT Observatory's initial facility AO system is a multi-conjugate AO system feeding science light from 0.8 to 2.5 microns wavelength to several near-IR client instruments. NFIRAOS has two deformable mirrors optically conjugated to 0 and 11.2 km, and will correct atmospheric turbulence with 50 per cent sky coverage at the galactic pole. An important requirement is to have very low background: the plan is to cool the optics; and one DM is on a tip/tilt stage to reduce surface count. NFIRAOS' real time control uses multiple sodium laser wavefront sensors and up to three IR natural guide star tip/tilt and/or tip/tilt/focus sensors located within each client instrument. Extremely large telescopes are sensitive to errors due to the variability of the sodium layer. To reduce this sensitivity, NFIRAOS uses innovative algorithms coupled with Truth wavefront sensors to monitor a natural star at low bandwidth. It also includes an IR acquisition camera, and a high speed NGS WFS for operation without lasers. For calibration, NFIRAOS includes simulators of both natural stars at infinity and laser guide stars at varying range distance. Because astrometry is an important science programme for NFIRAOS, there is a precision pinhole mask deployable at the input focal plane. This mask is illuminated by a science wavelength and flat-field calibrator that shines light into NFIRAOS' entrance window. We report on recent effort especially including trade studies to reduce field distortion in the science path and to reduce cost and complexity.

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Glen Herriot, David Andersen, Jennifer Atwood, Corinne Boyer, Annie Beauvillier, Peter Byrnes, Rod Conan, Brent Ellerbroek, Joeleff Fitzsimmons, Luc Gilles, Paul Hickson, Alexis Hill, Kate Jackson, Olivier Lardière, John Pazder, Thomas Pfrommer, Vlad Reshetov, Scott Roberts, Jean-Pierre Véran, Lianqi Wang, and Ivan Wevers "NFIRAOS: TMT's facility adaptive optics system", Proc. SPIE 7736, Adaptive Optics Systems II, 77360B (12 July 2010); https://doi.org/10.1117/12.857662

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