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Proceedings Paper

Contamination measurements during development and testing of the SPIRIT III cryogenic infrared telescope
Author(s): James S. Dyer; Russell S. Mikesell; Radford L. Perry; Tracy Mikesell; James J. Guregian
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Paper Abstract

The 10.6 (mu) bi-directional reflectance distribution function (BRDF) of the SPIRIT III primary mirror was measured after each major phase of sensor development and testing. The compiled BRDF history provides useful insights with respect to the cleanliness levels that may be reasonably expected for a cryogenic infrared sensor of this size and complexity. The use of nitrogen blow-off was demonstrated as an effective, low-risk option for `touching-up' critical infrared optics. The BRDF measured before integration with the MSX spacecraft was consistent with the scatter that would be produced by a surface cleanliness of near Level 100. Follow-on BRDF measurements will not be possible, since the SPIRIT III sensor will remain cold and under vacuum throughout spacecraft processing. An internal cryogenic quartz crystal microbalance has been used to monitor molecular redistribution processes that may occur when internal temperatures change during cryogen refills of other cryo-vacuum operations. The CQCM data is easily understood, and will provide a valuable diagnostic during pre-launch processing of the SPIRIT III cryostat.

Paper Details

Date Published: 19 October 1994
PDF: 15 pages
Proc. SPIE 2261, Optical System Contamination: Effects, Measurements, and Control IV, (19 October 1994); doi: 10.1117/12.190146
Show Author Affiliations
James S. Dyer, Utah State Univ. (United States)
Russell S. Mikesell, Utah State Univ. (United States)
Radford L. Perry, Utah State Univ. (United States)
Tracy Mikesell, Utah State Univ. (United States)
James J. Guregian, Sensor Systems Group, Inc. (United States)


Published in SPIE Proceedings Vol. 2261:
Optical System Contamination: Effects, Measurements, and Control IV
A. Peter M. Glassford, Editor(s)

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