1 May 1986 Optical Damage Characterization Of Rain-Eroded IR Materials
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Proceedings Volume 0590, Infrared Technology and Applications; (1986); doi: 10.1117/12.951979
Event: 1985 International Technical Symposium/Europe, 1985, Cannes, France
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.
© (1986) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
A. A. Deom, D. L. Balageas, G. Gardette, G. Gauffre, "Optical Damage Characterization Of Rain-Eroded IR Materials", Proc. SPIE 0590, Infrared Technology and Applications, (1 May 1986); doi: 10.1117/12.951979; https://doi.org/10.1117/12.951979
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KEYWORDS
Optical damage

Modulation transfer functions

Infrared materials

Spatial frequencies

Magnesium fluoride

Infrared radiation

Optical testing

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