Threshold distribution determination of laser-induced damage precursors in optical coatings and substrates

摘要

A statistical model for the interpretation of laser damage probability curves is investigated. In a previous study, shapes and slopes of the curves were related to the spot size and to the densities of nanodefects that are responsible for damage. Each kind of precursors was characterized by its damage threshold. We improved this study when considering a Gaussian distribution of precursor thresholds. Accurate probability curves of laser induced damage (1-on-1, 5-ns single shot at 1.064-μm) are then plotted in bulk and at the surfaces of optical components and fitted with the model including Gaussian distribution of precursor thresholds. Threshold mean value, threshold standard deviation and precursor defect densities are extracted for the different kinds of observed precursors. To illustrate our investigation, we present results achieved on different substrates, which establish a better agreement between theory and experiment.