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Proceedings Paper

Characterization of surface cleanliness with particulate obscuration
Author(s): Michael C. Fong; Aleck L. Lee
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Paper Abstract

An analysis has been performed to define the obscuration ratio (OR) of surface particles by considering not only the geometric cross sections of the particles but also their irradiance absorption/scattering characteristics. This analysis shows that part of the `extinct' irradiance due to interaction with the surface particles will be recovered by the surface via forward scatter of the radiant energy flux. Over-prediction of irradiance loss based on the often used assumption of opaque particles can thus be avoided. Consideration of the combined effect of absorption and forward scatter permits defining a more realistic effective OR. Sample solutions have shown that for opaque particles, the OR would be reduced by 50%, and for dust particles, the reduction would be by a factor of 10.

Paper Details

Date Published: 19 October 1994
PDF: 7 pages
Proc. SPIE 2261, Optical System Contamination: Effects, Measurements, and Control IV, (19 October 1994); doi: 10.1117/12.190135
Show Author Affiliations
Michael C. Fong, Lockheed Missiles & Space Co., Inc. (United States)
Aleck L. Lee, Lockheed Missiles & Space Co., 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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