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Proceedings Paper

Characterization of nodular and thermal defects in hafnia/silica multilayer coatings using optical, photothermal, and atomic force microscopy
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Paper Abstract

Multilayer coatings manufactured from metallic hafnium and silica sources by reactive electron beam deposition, are being developed for high fluence optics in a fusion lasers with a wavelength of 1053 nm and a 3 ns pulse length. Damage threshold studies have revealed a correlation between laser damage and nodular defects, but interestingly laser damage is also present in nodule-free regions. Photothermal studies of optical coatings reveal the existence of defects with strong optical absorption in nodule-free regions of the coating. A variety of microscopic techniques were employed to characterize the defects for a better understanding of the thermal properties of nodular defects and role of thermal defects in laser damage. Photothermal microscopy, utilizing the surface thermal lensing technique, was used to map the thermal characteristics of 3 mm X 3 mm areas of the coatings. High resolution subaperture scans, with a 1 micrometers step size and a 3 micrometers pump beam diameter, were conducted on the defects to characterize their photothermal properties. Optical and atomic force microscopy was used to visually identify defects and characterize their topography. The defects were then irradiated to determine the role of nodular and thermal defects in limiting the damage threshold of the multilayer.

Paper Details

Date Published: 20 April 1998
PDF: 9 pages
Proc. SPIE 3244, Laser-Induced Damage in Optical Materials: 1997, (20 April 1998); doi: 10.1117/12.307008
Show Author Affiliations
Christopher J. Stolz, Lawrence Livermore National Lab. (United States)
J. M. Yoshiyama, Lawrence Livermore National Lab. (United States)
Alberto Salleo, Lawrence Livermore National Lab. (United States)
Zhouling Wu, Eastern Michigan Univ. (United States)
John Green, Eastern Michigan Univ. (United States)
Rene Krupka, Eastern Michigan Univ. (Germany)

Published in SPIE Proceedings Vol. 3244:
Laser-Induced Damage in Optical Materials: 1997
Gregory J. Exarhos; Arthur H. Guenther; Mark R. Kozlowski; M. J. Soileau, Editor(s)

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