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Proceedings Paper

Optical design for an infrared imaging multi-object spectrometer (IRMOS)
Author(s): Robert S. Winsor; John W. MacKenty; Massimo Stiavelli; Matthew A. Greenhouse; John Eric Mentzell; Raymond G. Ohl; Richard F. Green
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Paper Abstract

The optical design for an Infrared Multiple Object Spectrometer (IRMOS) intended for Astronomical research is presented. To accomplish spectroscopy of multiple objects simultaneous, IRMOS utilizes a Micro- Mirror array (MMA) as an electronically controlled slit device. This approach makes object selection simple and offers great versatility for performing spectral analysis on many objects within a field location. Furthermore, it allows a field location to be imaged without spectra prior to object selection. The optical design of IRMOS has two distinct stages. The first stage reduces an f/15 incoming beam to f/4.5, with a tilted focal plane located at the MMA (the MMA removes some of the tilt of the focal plane, since the micro-mirrors tilt individually). The second stage consists of the spectrometer, capable of resolutions of 300, 1000, and 3000 in the astronomical J, H and K bands. This stage transforms the tilted focal plane into a collimated pupil on a grating, and then re-images onto a HAWAII detector. When used with the Kitt Peak National Observatory 4 meter telescope, a plate scale of approximately equals 0.2 arcseconds per pixel is realized at both the MMA and the detector. A total of 6 mirrors are used, two flat fold mirrors, two off-axis concave aspheres, one off-axis convex asphere, and one off-axis concave biconic mirror. The selection of a biconic surface in this design helped reduce the overall size of the instrument by reducing the size and number of necessary mirrors, simplifying alignment.

Paper Details

Date Published: 2 October 2000
PDF: 7 pages
Proc. SPIE 4092, Novel Optical Systems Design and Optimization III, (2 October 2000); doi: 10.1117/12.402425
Show Author Affiliations
Robert S. Winsor, Space Telescope Science Institute (United States)
John W. MacKenty, Space Telescope Science Institute (United States)
Massimo Stiavelli, Space Telescope Science Institute (United States)
Matthew A. Greenhouse, NASA Goddard Space Flight Ctr. (United States)
John Eric Mentzell, NASA Goddard Space Flight Ctr. (United States)
Raymond G. Ohl, NASA Goddard Space Flight Ctr. (United States)
Richard F. Green, National Optical Astronomy Observatories (United States)

Published in SPIE Proceedings Vol. 4092:
Novel Optical Systems Design and Optimization III
Jose M. Sasian, Editor(s)

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