Rain Erosion Damage Of Diamond-Like Coated Germanium

A. A. Deom; J. M. Mackowski; D. L. Balageas; P. Robert

doi:10.1117/12.951972

1 May 1986 Rain Erosion Damage Of Diamond-Like Coated Germanium

A. A. Deom, J. M. Mackowski, D. L. Balageas, P. Robert

Proceedings Volume 0590, Infrared Technology and Applications; (1986) https://doi.org/10.1117/12.951972
Event: 1985 International Technical Symposium/Europe, 1985, Cannes, France

Abstract

The rain erosion resistance of germanium may be improved by hydrogenated amorphous carbon (a-C:H) film coatings. a-C:H films are prepared by plasma deposition from hydrocarbons in RF diode glow discharge. The deposition parameters are adjusted to obtain controlled deposition rate and H/C ratio. The coatings are a quarter-wave thick at 10.6 μm. Their knoop micro-hardness is from 1800 to 2200 kgmm-2 for a 10-grams, 30-seconds load. The rain erosion is achieved with the Saab-Scania whirling-arm (Linkoping, Sweden). The impact velocity varies from 200 to 300 ms-l. The optical damage is characterized after each exposure, by modulation transfer function measurement. For 1.2 mm drop diameter the occurrence time of a given optical damage is increased by a factor of 6 to 7. For a 2 mm drop diameter, a factor of about 3 improvement is achieved. This last result is in good agreement with R.A.E. work. For 1.2 mm drop diameter the impingement angle effect is also reported and found in agreement with the sinus law.

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A. A. Deom, J. M. Mackowski, D. L. Balageas, and P. Robert "Rain Erosion Damage Of Diamond-Like Coated Germanium", Proc. SPIE 0590, Infrared Technology and Applications, (1 May 1986); https://doi.org/10.1117/12.951972

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