采用不同的光斑移动距离, 对电子束蒸发制备的HfO2/SiO2多层高反膜进行了单步及多步预处理。结果表明: 为了使薄膜不产生损伤, 预处理最高能量密度最好不超过薄膜零几率损伤阈值的90%; 相同预处理效率下进行的单步预处理对提高光学薄膜抗激光损伤阈值的效果比多步预处理好; 对HfO2/SiO2高反膜进行98.4%能量覆盖的两步预处理后薄膜损伤阈值提高81%; 控制薄膜的缺陷源, 初始物质应采用金属Hf。

Single-step and multi-step laser conditioning methods for HfO2/SiO2 multilayer high-reflective (HR) coatings prepared by electron-beam evaporation were introduced, with the use of different beam increment between pulses. In order not to damage the coating, the maximum conditioning fluence can not exceed 90% of its unconditioned laser induced damage threshold (LIDT). The LIDT enhancement of the coating after single-step conditioning is more than that after multi-step conditioning under the same conditioning efficiency. After two-step laser conditioning with a beam increment between pulses equal to the beam diameter at 98.4% of the peak intensity, the LIDT of the coating attains 181% of that of the unconditioned coating. The starting material composition for the hafnia layers has a direct impact on the concentration of defects imbedded in the coating, it is believed that coatings deposited from hafnium have defect-seeds at a significantly lower density.