反应等离子体修饰熔石英光学元件表面研究

Study of Surface Modification of Fused Silica Optical Component by Reactive Plasma

反应等离子体去除表面2.5μm后,元件表面面形保持平整光滑,大尺度均方根粗糙度小于1.45 nm(测量范围为0.9 mm×1.2 mm),表面Fe,Ce等杂质元素含量逐渐减少,划痕等物理缺陷的密度与尺寸变小。修饰之后的非晶熔石英元件表面出现具有周期性的多晶结构,该多晶结构可增强元件透射率,有效抑制损伤增长,提高元件损伤阈值。随修饰深度增加,元件的损伤概率进一步下降。研究表明通过提高等离子体密度、加大激励源功率等方法改进工艺路线,反应等离子体修饰有望实现熔石英元件的快速、无损、大面积和批量化处理。

After top layer of 2.5 μm being removed,surface of optical component becomes smooth and flat,and rms roughness is less than 1.45 nm in the range of 0.9 mm×1.2 mm.Content of impurity element（Fe,Ce ect.） is reduced and the size of sub-surface defect is decreased.Periodic polycrystal structure appears at surface of fused silica after being modificated resulting in the increment of transmittance from 400 to 1100 nm,damage is restrained and damage threshold raises.With increasing of modification depth,damage probability of optical component reduces further.Results indicate that reactive plasma modification will be a hopeful method for rapid and nondestructive processing of large surface fused silica optical component.