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Proceedings Paper

Diffraction Optical Modelling Of Far Infrared Spectrometers
Author(s): Michel Saisse; Patrick Rabou
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Paper Abstract

At far Infrared wavelengths (45 to 180 micrometers) the energy losses by diffraction at the different optical surfaces of a spectrometer cannot be neglected. A specific optical software has been develooped to simulate the multiple diffraction effects existing in the Long Wavelength Spectrometer (LWS), one of the four scientific instruments of the ESA Infrared Satellite ISO. The optical design of the spectrometer is briefly described, the interest of the use of an off-axis aspherical grating for a compact and flexible design is demonstrated. The mathematical model based on the Fourier-Fraunhofer diffraction theory is explained. The diffraction effects due to the wavefront limitation, at the relevant levels, and the wavefront aberrations of the spectrometer are modelled. The main results are given and discussed. The emphasis is set on the study of the energy losses due to multiple diffractions. Finally this model has been used to optimise the LWS optics and to define tolerances for the manufacturing and the adjustment of the optical system.

Paper Details

Date Published: 13 April 1989
PDF: 8 pages
Proc. SPIE 1013, Optical Design Methods, Applications and Large Optics, (13 April 1989); doi: 10.1117/12.949363
Show Author Affiliations
Michel Saisse, Laboratoire d'Astronomie Spatiale (France)
Patrick Rabou, Laboratoire d'Astronomie Spatiale (France)

Published in SPIE Proceedings Vol. 1013:
Optical Design Methods, Applications and Large Optics
Andre Masson; Joachim J. Schulte-in-den-Baeumen; Hannfried Zuegge, Editor(s)

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