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Proceedings Paper

Moisture barrier coatings to prevent environmental degradation of KDP crystals
Author(s): Amy L. Rigatti; Douglas J. Smith; Gary L. Mitchell; Jane Dirmyer; Ansgar W. Schmid; Semyon Papernov
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Paper Abstract

Degradation of sol-gel coated KDP surfaces has been observed in crystals used on the OMEGA laser system in 40-50% relative humidity environments. The defect characteristic is an etch pit which develops under the sol-gel coating and produces a significant loss in the crystal due to scatter. Both diamond-turned and polished KDP surfaces show evidence of defect growth after sol-gel coating and exposure to ambient conditions; however, there is no relationship between defect growth and exposure to laser radiation. The defect size, orientation, and density is uniform across a diamond-turned surface, and the growth rate is accelerated with exposure to higher relative humidity. Experiments with a thermosetting polysiloxane and polymethylmethacrylate (PMMA) demonstrate these materials are successful barriers to prevent the transport of water vapor via the sol-gel coating to the KDP surface. Both materials meet the OMEGA laser damage threshold requirement and have been successfully applied to 300mm diameter KDP crystals.

Paper Details

Date Published: 12 April 2001
PDF: 1 pages
Proc. SPIE 4347, Laser-Induced Damage in Optical Materials: 2000, (12 April 2001); doi: 10.1117/12.425070
Show Author Affiliations
Amy L. Rigatti, Univ. of Rochester (United States)
Douglas J. Smith, Univ. of Rochester (United States)
Gary L. Mitchell, Univ. of Rochester (United States)
Jane Dirmyer, Univ. of Rochester (United States)
Ansgar W. Schmid, Univ. of Rochester (United States)
Semyon Papernov, Univ. of Rochester (United States)

Published in SPIE Proceedings Vol. 4347:
Laser-Induced Damage in Optical Materials: 2000
Gregory J. Exarhos; Arthur H. Guenther; Mark R. Kozlowski; Keith L. Lewis; M. J. Soileau, Editor(s)

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