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Proceedings Paper

FIFI LS: the optical design and diffraction analysis
Author(s): Walfried Raab; Leslie W. Looney; Albrecht Poglitsch; Norbert Geis; Rainer Hoenle; Dirk Rosenthal; Reinhard Genzel
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Paper Abstract

We present the optical system of the Field-Imaging Far-Infrared Line Spectrometer (FIFI LS) for the SOFIA airborne observatory. The instrument is designed to allow diffraction limited integral field spectroscopy in the far infrared wavelength range 42 to 210 microns. Two parallel wavelength channels (42 - 110 microns and 110 - 210 microns) employ Littrow mounted diffraction gratings with anamorphic collimators. Mirror image slicers in each channel rearrange the 5 × 5 pixel field of view along the 1 × 25 entrance slit of the grating spectrograph. The spectral resolution varies in the range of R = 1400 - 6500, depending on observing wavelength. The optical components in the image slicer is comprised of several mirrors with physical dimensions on the order of a few tens of wavelength. Consequently diffraction effects are a serious concern in the design of the optical system. Substantial effort in modeling diffraction effects throughout the optical system and its impact upon the expected performance of the instrument have been made. The results of the scalar diffraction analysis carried out with a commercial software package has been confirmed by a full vectorial analysis, showing negligible dependence of the diffraction effects on the polarization properties of the electromagnetic field.

Paper Details

Date Published: 3 March 2003
PDF: 9 pages
Proc. SPIE 4857, Airborne Telescope Systems II, (3 March 2003); doi: 10.1117/12.458629
Show Author Affiliations
Walfried Raab, Max-Planck-Institut fuer extraterrestrische Physik (Germany)
Leslie W. Looney, Max-Planck-Institut fuer extraterrestrische Physik (Germany)
Albrecht Poglitsch, Max-Planck-Institut fuer extraterrestrische Physik (Germany)
Norbert Geis, Max-Planck-Institut fuer extraterrestrische Physik (Germany)
Rainer Hoenle, Max-Planck-Institut fuer extraterrestrische Physik (Germany)
Dirk Rosenthal, Max-Planck-Institut fuer extraterrestrische Physik (Germany)
Reinhard Genzel, Max-Planck-Institut fuer extraterrestrische Physik (Germany)

Published in SPIE Proceedings Vol. 4857:
Airborne Telescope Systems II
Ramsey K. Melugin; Hans-Peter Roeser, Editor(s)

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