铝高反射镜表面球状微粒散射的单层薄膜调控特性  

Regulation Characteristics of Globular Particle Scattering on Aluminum High Reflector Surface by Monolayer Film

作　　者：杨伟荣 潘永强[1] 刘欢[1] 郑志奇 李栋 周泽林 Yang Weirong;Pan Yongqiang;Liu Huan;Zheng Zhiqi;Li Dong;Zhou Zelin(School of Opto-Elect romie Engineering,Xi'an Technological Uniersity,Xi'an 710021,Shaanxi,China)

机构地区：[1]西安工业大学光电工程学院,陕西西安710021

出　　处：《中国激光》2022年第18期41-46,共6页Chinese Journal of Lasers

基　　金：陕西省教育厅重点实验室科研计划项目(18JS054);陕西省自然科学基础研究计划项目(2018JM6031)。

摘　　要：为了降低金属高反射薄膜表面微粒污染物的光学散射,分析了金属铝膜表面不同厚度的SiO_(2)保护层薄膜上半径为100 nm的球状微粒污染物球心处的电场强度,取电场强度极小值点对应的SiO_(2)薄膜的物理厚度125 nm作为SiO_(2)薄膜的优化厚度,理论计算了当波长为632.8 nm的光束正入射时,镀有优化SiO_(2)保护层的铝膜表面的双向反射分布函数(BRDF)。研究结果显示,在-90°~90°散射角内,与不镀保护层相比,优化后膜层表面污染物的散射得到了显著降低,在反射光传输方向上,镀制保护层前后B_(R)×cosθ_(s)(B_(R)为双向反射分布函数,θ_(s)为散射角)分别为0.00855和0.00048。计算了原始膜系与优化膜系表面污染物的总散射损耗,分别为0.018609和6.09264×10^(-4),优化膜系使得表面微粒的总散射降低了96.73%。最后实验镀制了四种薄膜设计,测量了相同污染条件下四种膜系表面的污染物散射情况,证实了优化SiO_(2)薄膜保护层可降低微粒污染物散射。Objective For high-precision optical thin film devices,the scattering of optical surfaces has attracted widespread attention.When the beam enters the optical surface,the particles on the optical surface scatter the incident light and the scattered light deviates from the specular reflection direction,resulting in the loss of the effective optical signal of the system.Furthermore,when the scattered light reaches the detector surface through the optical system,it increases the stray light of the optical system,so that the influence of noise on the signal cannot be ignored and reduces the detection sensitivity of the optical system.In a high-energy laser system,even very weak light scattering influences the thermal absorption level and laser damage threshold of the film.In the reflective astronomical telescope system,the pollutants on the surface of optical elements reduce the optical performance of the devices and make the optical devices completely unusable.Presently,commonly used methods for reducing the scattering of particulate pollutants on the surface of optical elements mainly require keeping the optical surface clean and reducing pollutants on the optical surface.However,improper cleaning may fail to remove pollutants from the optical surface,damage the optical surface and increase additional light scattering.Furthermore,the material cost of pollution control for the environment where the optical elements are located is also huge.In the optical thin film evaporation process,the film particles are evaporated to the substrate surface together with the film molecules,and dot protrusions are formed on the substrate surface.This results in increasing scattering on the surface of the optical element.Here,the scattering of surface particles cannot be eliminated by cleaning and environmental maintenance.From the thin film vector scattering theory,this paper reduces the scattering amount of particulate pollutants on the optical surface by optimizing the film design,which does not require keeping the optical surface

关 键 词：薄膜 光学薄膜 光散射 薄膜散射 双向反射分布函数 

分 类 号：O484[理学—固体物理]