K9基片的亚表面损伤探测及化学腐蚀处理技术研究

Studies on subsurface damage detection and wet-etching process of K9 optics

研究了几种类型的腐蚀液对K9基片化学腐蚀的影响。通过腐蚀液对基片纵向腐蚀速度的变化初步判断了K9基片重沉积层的深度。考察了腐蚀前后基片表面参数的变化以及腐蚀对激光损伤阈值的影响。研究表明,特定的腐蚀液能够对K9基片进行平稳可控的腐蚀,并且腐蚀能提高其激光损伤阈值,其主要原因是去除了重沉积层及表面、亚表面缺陷中的污染物,但过多的腐蚀会暴露本来为重沉积层所掩盖的划痕等亚表面缺陷,所以腐蚀并非越深越好。同时,表面各种杂质与缺陷的去除能够提高材料的机械强度,从而也有利于提高材料的激光损伤阈值。

Effects of wet-etching with four kinds of etching solution on the surface of K9 optical components were examined. By investigating the change pattern of wet-etching rate at different depth and surface parameters before and after corrosion, the depth of polishing redeposition layer was estimated. When etched to the depth of 600 nm, the loose polishing redeposition layer and the subsurface damage of the optics were mostly removed, hence the laser damage threshold was improved. However, with 1 500 nm in etching depth, the subsurface flaws and cracks appeared which lowered the laser damage threshold of the optics. The result shows that certain solution etches K9 optics with controllable rate and the laser damage threshold of the optics is improved.