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 $mu@m with a range of spot sizes, a pulse length of 15 ns (full width at half maximum intensity), and each site was tested with 100 shots at a 10 Hz repetition rate. The damage threshold was essentially constant at around 2 J/cm$+2$/ 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 $mu@m 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.
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机译:已经检查了一系列正弦调制的等离子体沉积的硅氧烷氧化物,窄带反射器,以了解电场效应,缺陷型,表面粗糙度,厚度和激光损伤阈值上的涂覆吸收的相对作用。损坏阈值测量在0.532 $ MU @ M,尺寸范围为0.532 $ MU @ M,脉冲长度为15 ns(半最大强度全宽),每个站点以10 Hz重复率为100次射击测试。损坏阈值基本上恒定在2 j / cm $ + 2 $ /适用于所有样本,并且缺陷占主导地位。使用Wyko三维表面分析仪发现三种类型的拓扑缺陷,其中一个缺陷类型负责大部分损坏事件。假设该5 000万美元的半球形缺陷可以作为微透镜表现,这增强了底层涂层的峰值,或作为增强电场效应的中心。
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