在高能激光系统中, 反射膜的损伤生长特性和初始损伤一样重要。对薄膜损伤生长特性的研究将有助于探究反射膜损伤机制, 从而进一步有效地提高其抗激光损伤能力。使用电子束蒸发(EB)和离子束辅助(IAD)两种工艺制备了1 064 nm波长下的HfO2/SiO2反射膜, 利用四种尺寸的单分散的SiO2小球形成人工节瘤, 来研究薄膜镀制工艺和节瘤尺寸对节瘤损伤生长特性的影响。激光损伤测试结果表明: 节瘤损伤生长阈值基本随节瘤尺寸的增加而减小。EB工艺制备的反射膜中, 四种尺寸节瘤的损伤生长阈值都高于其初始损伤阈值, 而IAD工艺制备的反射膜中结果则相反。另外, IAD工艺要比EB工艺制备的反射膜中的节瘤在发生初始损伤后更易于损伤生长, 说明薄膜镀制工艺对节瘤的损伤生长速度有一定的影响。

Damage growth behaviors play an equal important role in limiting the laser resistance of high reflectors (HR) on high power laser systems as initial damage. In order to build damage mechanism and improve the laser resistance of coatings, it is necessary to obtain more information about damage growth behaviors. Thus a comparative experiment was designed to study the damage growth characteristics of different size of nodular defects in HfO2/SiO2 high reflectors working at 1 064 nm. Two kinds of HfO2/SiO2 high reflectors were prepared by EB and IAD process, respectively, and four sizes of SiO2 microspheres were used to create artificial nodules in these films. Then the relationship between damage growth characteristics with nodule size and film deposition processes was studied. Laser damage test results showed that the damage growth threshold decreased with the increase of nodule size for all sizes of nodules in both EB and IAD coatings. The damage growth threshold were higher than the initial damage threshold for all four sizes of nodules in coatings prepared by EB process, however, the results were opposite for all four sizes of nodules in coatings prepared by IAD process. Besides, IAD nodules were more easily to grow than EB nodules, which indicated that the film deposition processes has some influence on the damage growth speed of nodules.