Share Email Print
cover

Proceedings Paper

The infrared imaging spectrograph (IRIS) for TMT: imager design
Author(s): Ryuji Suzuki; Tomonori Usuda; David Crampton; James Larkin; Anna Moore; Andrew Phillips; Luc Simard
Format Member Price Non-Member Price
PDF $14.40 $18.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

We describe an optical design of an imager mode of the IRIS instrument for the Thirty Meter Telescope. IRIS is a fully-cryogenic diffraction-limited infrared camera and integral field spectrograph working in the wavelength coverage from 0.84 to 2.4 microns. The imager mode covers 16.4" × 16.4" FOV with a 4096 × 4096 detector array with sampling 4 milli-arcsec/pix. There are two challenges in performance which the science cases require in the imager mode. 1) rms wavefront error should be less than 30 nm, and 2) optical distortion should be corrected sufficiently to achieve astrometric accuracy of 10 micro-arcsec. Among possible optical configurations consisting of reflective and refractive solutions, a refractive solution with apochromatic triplets best meets the requirements. The optical system consists of a collimator and camera both of which have a BaF2-Fused Silica- ZnSe apochromatic triplet and a single BaF2 lens near the focus. The rms wavefront error of the system including the telescope, adaptive optics, and imager mode is less than 22 nm with ideal optical parameters. A sensitivity analysis shows that reasonable amount of errors in fabrication and alignment will give the rms wavefront error of less than 30 nm in 90 % of all cases. We also investigate accuracy of the distortion correction and how movable parts affect the correction accuracy. We find that uncorrectable distortion correction errors are well below 10 micro-arcsec with reasonable stability and repeatability of the movable parts.

Paper Details

Date Published: 21 July 2010
PDF: 10 pages
Proc. SPIE 7735, Ground-based and Airborne Instrumentation for Astronomy III, 77355S (21 July 2010); doi: 10.1117/12.857520
Show Author Affiliations
Ryuji Suzuki, Thirty Meter Telescope Observatory Corp. (United States)
National Astronomical Observatory of Japan, Subaru Telescope (United States)
Tomonori Usuda, National Astronomical Observatory of Japan, Subaru Telescope (United States)
David Crampton, Dominion Astrophysical Observatory, National Research Council Canada (Canada)
James Larkin, Univ. of California, Los Angeles (United States)
Anna Moore, Caltech Optical Observatories (United States)
Andrew Phillips, UCO, Ctr. for Adaptive Optics, Univ. of California, Santa Cruz (United States)
Luc Simard, Dominion Astrophysical Observatory, National Research Council Canada (Canada)


Published in SPIE Proceedings Vol. 7735:
Ground-based and Airborne Instrumentation for Astronomy III
Ian S. McLean; Suzanne K. Ramsay; Hideki Takami, Editor(s)

© SPIE. Terms of Use
Back to Top