Surface roughness and laser damage threshold

The essential results of a carefully controlled experimental investigation of the effect of roughness on laser-induced surface damage thresholds in fused silica are reported. Sets of fused silica samples were subjected to several surface preparations such that rms surface roughness values within each set varied over two orders of magnitude. A plot of surface damage threshold versus surface roughness shows that there is a strong dependence of threshold on roughness, that this dependence exhibits a simple functional form, and that this relationship appears to hold even for the smoothest of optical surfaces. The utility of the observed threshold-roughness relationship is discussed.