真空紫外波段Al膜保护层MgF_2的光学常数  

Optical constant of MgF_2 coatings for Al/MgF_2 mirror in vacuum ultraviolet region

作　　者：王风丽[1,2] 张壮壮 王占山[1,2] 周洪军[3] 霍同林[3] WANG Feng-li;ZHANG Zhuang-zhuang;WANG Zhan-shan;ZHOU Hong-jun;HUO Tong-lin(Key Laboratory of Advanced Structured Micro Materials, Ministry of Education, Institute of Precision Optical Engineering, Tongji University, Shanghai 200092, China;School of Physics Science and Engineering, Tongji University, Shanghai 200092, China;National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China)

机构地区：[1]同济大学教育部先进微结构材料重点实验室,上海200092 [2]同济大学物理科学与工程学院,上海200092 [3]中国科学技术大学国家同步辐射实验室,安徽合肥230029

出　　处：《光学精密工程》2017年第11期2823-2828,共6页Optics and Precision Engineering

基　　金：国家自然科学基金面上项目(No.11573020);国家重大仪器开发专项(No.2012YQ04016403;No.2012YQ13012505)

摘　　要：由于Al膜的保护层MgF_2薄膜的光学常数对Al/MgF_2高反射镜的性能有极大的影响,本文研究了获取MgF_2薄膜光学常数的方法。用热舟蒸发的方法在室温B270基底上镀制了3块不同MgF_2厚度的Al/MgF_2反射镜样品,通过掠入射X射线小角反射方法表征样品,获得了膜层厚度和粗糙度。在国家同步辐射实验中心计量站测试了入射角为5°时,样品在105~130nm波段的反射率。在Al、MgF_2膜层的厚度和Al的光学常数已知条件下,依据菲涅尔公式,得出了满足某波长处样品反射率的等值曲线,然后从三条曲线的交点得出了MgF_2薄膜在108~128nm波段的光学常数。对比和分析显示:利用此方法得到的108~128nm波段MgF_2薄膜光学常数计算的反射率曲线和实际测试得到的反射率曲线吻合较好。As the optical constant of MgF2over coated Al mirror effects its optical performance greatly,this paper explores the method to obtain the optical constant.Three Al/MgF2mirror samples covered by MgF2coatings with different thicknesses were deposited on B270substrates at room temperature by thermal evaporation method.The layer structures of the samples such as the thickness and the roughness were characterized by the grazing incidence X ray reflectometry.The reflectivities of the samples at a incidence angle of5°were measured in105-130nm region at the National Synchrotron Radiation Laboratory(NSRL).Finally,the optical constant of MgF2for Al/MgF2mirror was obtained by Fresnel formulas at given wavelength and corresponding reflectivity when the coating thicknesses of MgF2,Al,and the optical constant of Al have been known.The common intersection point of the curves of three MgF2coatings with different thickness for Al/MgF2mirror determines the optical constant of MgF2coating at given wavelength.The analysis and comparison show that calculated reflectivity from optical constants of this work agrees well with measured reflectivity curves in108-128nm region.

关 键 词：真空紫外 反射镜 保护层 光学常数 菲涅尔公式 热蒸发 

分 类 号：O484.4[理学—固体物理]