Comparison of defects responsible for nanosecond laser-induced damage and ablation in common high index optical coatings

Spatiotemporally resolved optical laser-induced damage is an experimental technique used to study nanosecond laser damage and initiation of ablation in dielectric metal-oxide films used for optical coatings. It measures the fluence (intensity) at the initiation of damage during a single laser pulse. The technique was applied to coatings of HfO 2 , Sc 2 O 3 , and Ta 2 O 5 , which were prepared by ion-beam sputtering, and HfO 2 which was prepared by electron-beam evaporation. Using the data obtained, we were able to retrieve the defect density distributions of these films without a priori assumptions about their functional form.