Abstract

Laser conditioning is one of the important methods to improve laser induced damage threshold (LIDT) of laser films. In this work, large aperture laser was used to irradiate to the HfO₂/SiO₂ reflectors, which were evaporated by e-beam. Laser calorimeter was used to test the film absorption before and after laser irradiation. Especially, Focused ion beam (FIB) was few reported using on laser films, in our work, it was used to study the damage morphology and exploring the cause of damage. For the first time shoot the partial ejection on nodule, which provide the basis for studying nodule damage-mechanism. The results show that film absorption was decreased obviously after the laser irradiation. For the HfO₂/SiO₂ reflectors, studying from the FIB result, laser conditioning was effective to eject the nodules on substrate, which was result from the nodule was ejected completely and the residue not to affect the subsequent laser. In addition, laser conditioning was not effective to the nodule in the film, which may be from the material spatter in coating process. It was result from the nodule was ejected partially and the residue seed was intensity absorption source. In that case, other method can be used to get rid of the nodules. All the results show the laser conditioning is an effective method for improving the laser film damage threshold.

© 2013 Optical Society of America