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Proceedings Paper

Laser damage studies of silicon oxy-nitride narrowband reflectors
Author(s): Jonathan R. Milward; Keith L. Lewis; K. Sheach; Rudolf August Heinecke
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Paper Abstract

A series of sinusoidally modulated, plasma deposited, silicon oxy-nitride, narrow band reflectors have been examined with a view to understanding the relative roles of electric field effects, defect type, surface roughness, thickness, and coating absorption on the laser damage threshold. The damage threshold measurements were made at 0.532 micrometers with a range of spot sizes, a pulse length of 15 ns (full width at half maximum intensity), and each site was tested with 100 shots at a 10 Hz repetition rate. The damage threshold was essentially constant at around 2 J/cm2 for all the samples, and was defect dominated. Three types of topological defects were discovered using a WYKO three dimensional surface profiler, and one of the defect types was responsible for a large fraction of the damage events. It is postulated that this 5 micrometers hemispherical defect may behave either as a microlens which enhances the peak fluence that the underlying coating is subjected to, or as a center for enhanced electric field effects.

Paper Details

Date Published: 24 June 1993
PDF: 10 pages
Proc. SPIE 1848, 24th Annual Boulder Damage Symposium Proceedings -- Laser-Induced Damage in Optical Materials: 1992, (24 June 1993); doi: 10.1117/12.147431
Show Author Affiliations
Jonathan R. Milward, Defence Research Agency (United Kingdom)
Keith L. Lewis, Defence Research Agency (United Kingdom)
K. Sheach, BNR Europe (United Kingdom)
Rudolf August Heinecke, BNR Europe (United Kingdom)

Published in SPIE Proceedings Vol. 1848:
24th Annual Boulder Damage Symposium Proceedings -- Laser-Induced Damage in Optical Materials: 1992
Harold E. Bennett; Lloyd L. Chase; Arthur H. Guenther; Brian Emerson Newnam; M. J. Soileau, Editor(s)

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