NFIRAOS: TMT facility adaptive optics with conventional DMs
Abstract
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.
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).Attached Files
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Additional details
- Eprint ID
- 95577
- Resolver ID
- CaltechAUTHORS:20190517-152013247
- Association of Universities for Research in Astronomy (AURA)
- Association of Canadian Universities for Research in Astronomy (ACURA)
- Caltech
- University of California
- Gordon and Betty Moore Foundation
- NSF
- National Research Council of Canada
- Gemini Partnership
- Natural Sciences and Engineering Research Council of Canada (NSERC)
- Created
-
2019-05-20Created from EPrint's datestamp field
- Updated
-
2021-11-16Created from EPrint's last_modified field
- Caltech groups
- Thirty Meter Telescope
- Series Name
- Proceedings of SPIE
- Series Volume or Issue Number
- 5903