Laser damage resistant multiband high reflective optics

摘要

Laser durable multiband high reflective optics can be realized by depositing densified HfO_2/SiO_2 multilayers on aluminum alloy substrates. To further understand the impact of surface finishing and cleaning on laser-induced damage of multiband high reflective optics, 1" diameter witness samples were characterized by means of spectrophotometry, atomic force microscopy, confocal laser scanning microscopy, white light interferometry, scanning electron microscopy, and laser-induced damage threshold tests performed at 1064 nm, 20 ns, 20 Hz, and near normal angle of incidence. Laser-induced damage thresholds of 12.5 J/cm~2 and 47 J/cm~2 were obtained on a stained witness and unstained witness, respectively. A two-step laser damage process was proposed based on the post-damage analysis. The results suggest that nodule defects are the limiting factor for laser-induced damage thresholds. There exists the potential in aluminum-based dielectric coated multiband reflective optics for extremely high power laser applications.