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Angular Dependence of Thin-Film Dielectric Coating Damage Thresholds Revisited
Boyer, JD
Los Alamos National Laboratory, New Mexico

Foltyn, SR

Mauro, BR

Sanders, VE


Pages: 8    Published: Jan 1990


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Source: STP1117-EB


Abstract

Newnam et al. [1] reported experiments showing that the angular dependence of 351-nm laser damage thresholds in HfO2/SiO2 multilayer dielectric reflectors was much weaker than even the 1/cosθ expected from simple geometric fluence dilution. Several plausible explanations were suggested, but none were convincing. We propose a simple geometric model based on a cylindrical form for the coating defect responsible for damage initiation. We have measured 248-nm damage thresholds for bare fused silica, evaporated aluminium films, and HfO2/SiO2 and Al2O3/SiO2 dielectric reflectors at angles out to 85°. The measured data agree well with our simple model.


Keywords:
angular dependence, aluminium oxide, coating defects, evaporated aluminium, fused silica, hafnium oxide, laser damage thresholds, multilayer dielectric reflectors, silicon dioxide

Paper ID: STP26509S
Committee/Subcommittee: E13.15
DOI: 10.1520/STP26509S
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