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Proceedings Paper

NFIRAOS: TMT's facility adaptive optics system
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Paper 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.

Paper Details

Date Published: 13 July 2010
PDF: 8 pages
Proc. SPIE 7736, Adaptive Optics Systems II, 77360B (13 July 2010); doi: 10.1117/12.857662
Show Author Affiliations
Glen Herriot, NRC Herzberg Institute of Astrophysics (Canada)
David Andersen, NRC Herzberg Institute of Astrophysics (Canada)
Jennifer Atwood, NRC Herzberg Institute of Astrophysics (Canada)
Corinne Boyer, TMT Observatory Corp. (United States)
Annie Beauvillier, NRC Herzberg Institute of Astrophysics (Canada)
Peter Byrnes, NRC Herzberg Institute of Astrophysics (Canada)
Rod Conan, Univ. of Victoria (Canada)
Brent Ellerbroek, TMT Observatory Corp. (United States)
Joeleff Fitzsimmons, NRC Herzberg Institute of Astrophysics (Canada)
Luc Gilles, TMT Observatory Corp. (United States)
Paul Hickson, The Univ. of British Columbia (Canada)
Alexis Hill, NRC Herzberg Institute of Astrophysics (Canada)
Kate Jackson, Univ. of Victoria (Canada)
Olivier Lardière, Univ. of Victoria (Canada)
John Pazder, NRC Herzberg Institute of Astrophysics (Canada)
Thomas Pfrommer, The Univ. of British Columbia (Canada)
Vlad Reshetov, NRC Herzberg Institute of Astrophysics (Canada)
Scott Roberts, NRC Herzberg Institute of Astrophysics (Canada)
Jean-Pierre Véran, NRC Herzberg Institute of Astrophysics (Canada)
Lianqi Wang, TMT Observatory Corp. (United States)
Ivan Wevers, NRC Herzberg Institute of Astrophysics (Canada)


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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