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Proceedings Paper

Slit function measurements of an imaging spectrograph using Fourier transform techniques
Author(s): Hongwoo Park; Bruce Miles Swinyard; Peter Jakobsen; Samuel Harvey Moseley Jr.; Matthew A. Greenhouse
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Paper Abstract

Knowledge of a spectrograph slit function is necessary to interpret unresolved lines and spectral features in an observed spectrum. In a scanning spectrometer with a single exit slit, the slit function is easily measured by illuminating the entrance slit with a broadband source and scanning the dispersive element. In a fixed grating/or disperser spectrograph, the slit functions have been measured by illuminating the entrance slit with a monochromatic light using a premonochromator or a tunable laser and by varying the wavelength of the incident light. Generally these techniques are very expensive, complex or subject to a poor signal-to-noise ratio so that an accurate measurement is often not possible. Also it would be very laborious and prohibitive to an imaging spectrograph or a multi-object spectrograph that has many sets of entrance and exit slit equivalents. We explore an alternative technique that is manageable for the measurements and where the measurement is not limited by the available signal. In the proposed technique, a Fourier Transform Spectrometer (FTS) is used instead of a pre-monochromator with variable wavelengths in the conventional techniques. This approach can be extended to the visible and ultraviolet (UV) wavelength range and to imaging spectrographs and multi-object spectrograph where multiple entrance slits and multiple exit slit equivalents (detectors) produce numerous different slit functions. In this approach, the advantages of FTS are fully utilized for available signals and the computer-assisted nature of FTS makes the data processing of the measurements manageable.

Paper Details

Date Published: 12 October 2004
PDF: 7 pages
Proc. SPIE 5487, Optical, Infrared, and Millimeter Space Telescopes, (12 October 2004); doi: 10.1117/12.552285
Show Author Affiliations
Hongwoo Park, NASA Goddard Space Flight Ctr. (United States)
Bruce Miles Swinyard, Rutherford Appleton Lab. (United Kingdom)
Peter Jakobsen, European Space Agency/ESTEC (Netherlands)
Samuel Harvey Moseley Jr., NASA Goddard Space Flight Ctr. (United States)
Matthew A. Greenhouse, NASA Goddard Space Flight Ctr. (United States)

Published in SPIE Proceedings Vol. 5487:
Optical, Infrared, and Millimeter Space Telescopes
John C. Mather, Editor(s)

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