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Proceedings Paper

Optical Damage Characterization Of Rain-Eroded IR Materials
Author(s): A. A. Deom; D. L. Balageas; G. Gardette; G. Gauffre
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Paper Abstract

The action of rain on irdome materials can lead to important damages. A comparative study of optical damages and of erosion is conducted for various infrared materials. The sample erosion is characterized by conventional mass loss measurements. The optical damage is characterized, after each rain exposure, by the modulation transfer function (MFT) measurement. An optical infrared set-up allows MFT measurements for spatial frequencies from 66 to 1000 cycles/rad. and various spectral ranges: 2-12 μm,2-3 μm,3.5-6 μm and 8-12 μm. The dependence of MFT wear on impact velocity is similar to that of the mass loss: occurence time of damages is inversely proportionnal to a high-exponent power law of the velocity. This exponent is characteristic of the material. The optical damage depends on the spectral range and the spatial frequency. This last point justifies the use of the MFT measurement. For some materials, the optical damage occurs in synchronism with the erosion, and for others before the beginning of the erosion. Thereby, the infrared material screening must be achieved by MFT measurements rather than by mass loss measurements.

Paper Details

Date Published: 1 May 1986
PDF: 7 pages
Proc. SPIE 0590, Infrared Technology and Applications, (1 May 1986); doi: 10.1117/12.951979
Show Author Affiliations
A. A. Deom, Office National d'Etudes et de Recherches Aerospatiales (ONERA) (France)
D. L. Balageas, Office National d'Etudes et de Recherches Aerospatiales (ONERA) (France)
G. Gardette, Office National d'Etudes et de Recherches Aerospatiales (ONERA) (France)
G. Gauffre, Office National d'Etudes et de Recherches Aerospatiales (ONERA) (France)

Published in SPIE Proceedings Vol. 0590:
Infrared Technology and Applications
Lionel R. Baker; Andre Masson, Editor(s)

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