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Proceedings Paper

Materials for high-energy laser windows: oxyfluoride glass vs. fusion-cast CaF2
Author(s): Claude A. Klein
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Paper Abstract

The process of selecting suitable materials for high-energy laser windows involves considerations realting to (a) the flexural strength, (b) the thermal stresses, and (c) the optical distortion. Optical distortion ocnsiderations strongly favor low-absorbtion materials ythat exhibit a negitive thermo-optic coefficient (dn/dT) in conjunction with minimal stress-birefringence (q&dverline; -q⊥ ≃0). For this reason, calcium floride has been the primary candidate for many years, but the efforts to strengthen this material have not been successful. Recently, a new glass compostion-oxyfloride glass (OFG)-has been promoted as an ideal solution in the sense that it will allow fabricating large "athermal" windows for operation at the chemical oxygen-iodine laser wavelength. It is, therefore, of interest to properly assess the merits of OFG in comparison to CaF2, which we do here on the basis of available (Dec '04) property data for fusion-cast CaF2 and OFG. Oxyfloride glass was found to be deficient in regard to thermal diffusivity, which may lead to excessive coating-induced compressive stresses, and stress- birefringence, which rules out creating a distortion-free window. It is suggested that future efforts should be directed at strengthening CaF2 in view of this material's exceptionally low absorbtion and almost no stress-birefringence

Paper Details

Date Published: 18 May 2005
PDF: 16 pages
Proc. SPIE 5786, Window and Dome Technologies and Materials IX, (18 May 2005); doi: 10.1117/12.603242
Show Author Affiliations
Claude A. Klein, c.a.k. analytics, international (United States)


Published in SPIE Proceedings Vol. 5786:
Window and Dome Technologies and Materials IX
Randal W. Tustison, Editor(s)

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