Study on Laser Conditioning Parameters of HfO2/SiO2 Mul tilayer Mirrors

Laser conditioning is an effective method to improve the laser damage threshold of HfO2/SiO2 multilayer films prepared by electron beam evaporation. In this paper, some parameters that can affect the efficiency of laser conditioning were discussed. The result is that the maximum conditioning fluence should be less than 90% of its unconditioned laser induced damage threshold (LIDT) to avoid damage to the film. The laser beam increment between pulses and laser conditioning steps has a great influence on the improvement of damage threshold of HfO2/SiO2 multilayer high reflective coatings. The coverage of the light intensity on the defect should be as wide as possible, and the irradiation of light intensity should be as high as possible. The main mechanisms of laser conditioning of HfO2/SiO2 multilayer high reflective coatings may be the removal of Hf, Si and O ions and the removal of the defects in the films.