Scattered Light as a Laser Damage Diagnostic
SourceLaser light scattering from thin film coatings was evaluated as a diagnostic indicator for an automated 1-on-l laser damage test facility. While variations in scattered light has been effectively used in bulk damage testing for many years, a dependable diagnostic of similar ilk for threshold phenomena of surfaces and thin film coatings has not been universally accepted. The data collected in this study indicates that measurement of scattered light is effective when surface damage morphologies mimic the larger scale phenomena observed in bulk damage. When individual micron diameter pits form on the surface, as can frequently be the case, this diagnostic is less reliable. In addition, when the overall scatter level from the surface is high, as in poor quality optics, the change in scattered light becomes undetectable with the onset of damage.