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Proceedings Paper

APART/PADE Analytical Evaluation Of The Diffuse Infrared Background Experiment For NASA's Cosmic Background Explorer
Author(s): Dennis Charles Evans; Robert P. Breault
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Paper Abstract

The stray light performance of NASA's Diffuse Infrared Background Experiment (DIRBE) has been calculated using the APART/PADE code. That code has been upgraded to handle off-axis optical systems such as DIRBE. Under observing conditions, sunlight is attenuated by 21 to 29 orders-of-magnitude; uniform diffuse illumination, by 6 to 9 orders of magnitude. The sunlight is attenuated by multiple diffraction at an external sun shield and by a forebaffle at the entrance to the DIRBE. Stray light is nearly a linear function of the Bidirectional Reflectance Distribution Function (BRDF) of the primary mirror at all wavelengths - or it can be made to be so by reducing the size of the field defining stop from 0.866 to 0.7 degrees square. For uniform diffuse illumination, half of the stray radiation comes from within 5 degrees of the center of the field-of-view. Particulate contamination of the primary mirror is expected to be a problem and special polishing and cleaning procedures are recommended - before mirror overcoating and again before flight.

Paper Details

Date Published: 17 January 1985
PDF: 11 pages
Proc. SPIE 0511, Stray Radiation IV, (17 January 1985); doi: 10.1117/12.945036
Show Author Affiliations
Dennis Charles Evans, Sachs/Freeman Associates, Inc. (United States)
Robert P. Breault, Breault Research Organization, Incorporated (United States)

Published in SPIE Proceedings Vol. 0511:
Stray Radiation IV
Robert P. Breault, Editor(s)

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