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Proceedings Article

NFIRAOS: TMT's facility adaptive optics system

[+] Author Affiliations
Glen Herriot, David Andersen, Jennifer Atwood, Annie Beauvillier, Peter Byrnes, Joeleff Fitzsimmons, Alexis Hill, John Pazder, Vlad Reshetov, Scott Roberts, Jean-Pierre Véran, Ivan Wevers

NRC Herzberg Institute of Astrophysics (Canada)

Corinne Boyer, Brent Ellerbroek, Luc Gilles, Lianqi Wang

TMT Observatory Corp. (USA)

Rod Conan, Kate Jackson, Olivier Lardière

Univ. of Victoria (Canada)

Paul Hickson, Thomas Pfrommer

The Univ. of British Columbia (Canada)

Proc. SPIE 7736, Adaptive Optics Systems II, 77360B (July 12, 2010); doi:10.1117/12.857662
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From Conference Volume 7736

  • Adaptive Optics Systems II
  • Brent L. Ellerbroek; Michael Hart; Norbert Hubin; Peter L. Wizinowich
  • San Diego, California, USA | June 27, 2010


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.

© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Glen Herriot ; David Andersen ; Jennifer Atwood ; Corinne Boyer ; Annie Beauvillier, et al.
"NFIRAOS: TMT's facility adaptive optics system", Proc. SPIE 7736, Adaptive Optics Systems II, 77360B (July 12, 2010); doi:10.1117/12.857662; http://dx.doi.org/10.1117/12.857662

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