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NFIRAOS: TMT facility adaptive optics with conventional DMs

Herriot, Glen and Hickson, Paul and Ellerbroek, B. L. and Andersen, D. A. and Davidge, T. and Erickson, D. A. and Powell, I. P. and Clare, R. and Smith, M. and Saddlemyer, L. and Véran, J.-P. (2005) NFIRAOS: TMT facility adaptive optics with conventional DMs. In: Astronomical Adaptive Optics Systems and Applications II. Proceedings of SPIE. No.5903. Society of Photo-Optical Instrumentation Engineers (SPIE) , Bellingham, WA, Art. No. 590302. ISBN 9780819459084.

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Although many of the instruments planned for the TMT (Thirty Meter Telescope) have their own closely-coupled adaptive optics systems, TMT will also have a facility Adaptive Optics (AO) system feeding three instruments on the Nasmyth platform. For this Narrow-Field Infrared Adaptive Optics System, NFIRAOS (pronounced nefarious), the TMT project considered two architectures. One, described in this paper, employs conventional deformable mirrors with large diameters of about 300 mm and this is the reference design adopted by the TMT project. An alternative design based on MEMS was also studied, and is being presented separately in this conference. The requirements for NFIRAOS include 0.8-5 microns wavelength range, 30 arcsecond diameter output field of view (FOV), excellent sky coverage, and diffraction- limited atmospheric turbulence compensation (specified at 133 nm RMS including residual telescope and science instrument errors.) The reference design for NFIRAOS includes multiple sodium laser guide stars over a 70 arcsecond FOV, and an infrared tip/tilt/focus/astigmatism natural guide star sensor within instruments. Larger telescopes require greater deformable mirror (DM) stroke. Although initially NFIRAOS will correct a 10 arcsecond science field, it uses two deformable mirrors in series, partly to provide sufficient stroke for atmospheric correction over the 30 m telescope aperture, but mainly to partially correct a 2 arcminute diameter "technical" field to sharpen near-IR natural guide stars and improve sky coverage. The planned upgrade to full performance includes replacing the groundconjugated DM with a higher actuator density, and using a deformable telescope secondary mirror as a "woofer." NFIRAOS incorporates an instrument rotator and selection of three live instruments: a near-Infrared integral field Imaging spectrograph, a near-infrared echelle spectrograph, and after upgrading NFIRAOS to full multi-conjugation, a wide field (30 arcsecond) infrared camera.

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Smith, M.0000-0002-3321-1432
Additional Information:© 2005 Society of Photo-Optical Instrumentation Engineers (SPIE). The authors present this paper as part of the work of the Thirty Meter Telescope (TMT) Project. TMT is a partnership of the Association of Universities for Research in Astronomy (AURA), the Association of Canadian Universities for Research in Astronomy (ACURA), the California Institute of Technology and the University of California. The partners gratefully acknowledge the support of the Gordon and Betty Moore Foundation, the US National Science Foundation, the National Research Council of Canada (NRC), the Gemini Partnership and the Natural Science and Engineering Research Council Canada (NSERC).
Group:Thirty Meter Telescope
Funding AgencyGrant Number
Association of Universities for Research in Astronomy (AURA)UNSPECIFIED
Association of Canadian Universities for Research in Astronomy (ACURA)UNSPECIFIED
University of CaliforniaUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
National Research Council of CanadaUNSPECIFIED
Gemini PartnershipUNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Subject Keywords:TMT, Thirty Meter Telescope, adaptive optics, NFIRAOS
Series Name:Proceedings of SPIE
Issue or Number:5903
Record Number:CaltechAUTHORS:20190517-152013247
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Official Citation:Glen Herriot, Paul Hickson, B. L. Ellerbroek, David A. Andersen, T. Davidge, D. A. Erickson, I. P. Powell, R. Clare, M. Smith, L. Saddlemyer, and J.-P. Veran "NFIRAOS: TMT facility adaptive optics with conventional DMs", Proc. SPIE 5903, Astronomical Adaptive Optics Systems and Applications II, 590302 (25 August 2005); doi: 10.1117/12.617849;
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:95577
Deposited By: Tony Diaz
Deposited On:20 May 2019 16:32
Last Modified:09 Mar 2020 13:19

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