HfO2／SiO2高反射膜的缺陷及其激光损伤

用原子力、Normaski和扫描电子显微镜等分析仪器，对高损伤阈值薄膜常采用HfO2/SiO2薄膜进行了表面显微图象研究，分析了薄膜常见的表面缺陷，如节瘤，孔洞和划痕等。薄膜表面缺陷的激光损伤实验表明，不同缺陷的抗激光损伤能力不大相同。节瘤缺陷最低，约为15J/cm^2，薄膜的损伤阈值主要由其决定，孔洞的激光损伤能力与节瘤相比较高，约为节瘤的2－3倍。节瘤缺陷在低能量密度的激光损伤所形成的孔洞，与镀制过程中形成的孔洞形貌相似，激光再损伤能力也相似。低能量密度的激光把瘤缺陷变为孔洞缺陷是激光预处理提高薄膜损伤阈值的原因之一。

Relation between laser damage and defects of HfO2

In the application of high power lasers,damage of coating multilayers of laser systems mainly limits the laser performance,so there is great interest in reducing the susceptibility of optical coating damage.In this paper,defects of HfO 2/SiO 2 high reflected coatings and their laser damage are studied in details.The coating samples were deposited by e beam evaporation onto K 9 glass substrates using hafnia silica materials.The defects and damage morphologies of coating were observed and analyzed by AFM,Normaski and SEM microscopes.In damage experiment,it was found that the coating onset damage is mainly caused by nodular defect.The laser energy density for damaging the pits (flat bottom pits for example) is 2-3 times as that (about 15J/cm 2) for damaging nodular.The size and anti damage ability of the pits formed from nodular damage is similar to that of the pits formed from the coatings deposition.The low energy density laser's turning nodulars into pits is one of the reasons that laser pretreatment improves the damage threshold of the hafina/silica coatings