Effect of 1 064 nm laser conditioning on damage morphology change process on HfO₂/SiO₂ reflective film

The effects of varied laser conditioning parameters on the damage morphology change process of HfO2/SiO2 reflective film under nanosecond pulse were experimentally studied in this paper. By comparing of damage expansion and the influence on spectra for two types of damage, the role of laser conditioning is illuminated to restrain the process of damage morphology change process. The two contrary impacts of laser conditioning on thin film, nodule clean up and absorbing precursor formation, were revealed by damage morphology analysis. The experiment result shows that the contours of damage morphology change thresholds will shift to higher laser fluence and more shots after laser conditioning. In addition, considering efficiency and profit of laser conditioning, the combination of higher laser fluence and two scanning steps could have the best choice in morphology changing elimination, and the morphology change threshold could increase to 140% in the best case.