真空紫外Al/MgF 2 反射镜

Al/MgF2 mirrors in vacuum ultraviolet region were developed by three step thermal boat evaporation method,and a method to improve the reflectivity of mirrors by fabrication technology was explored.There are three steps to fabricate the two layers Al/MgF2 mirrors.In the first step,an aluminum coating with a thickness about 70 nm was evaporated on a quartz substrate at the room temperature.And then,the MgF2 coating with a thickness about 10 nm was quickly evaporated on an aluminum coating.In the third step,the substrate was heated to certain temperature,and the MgF2 coating with a thickness of 15-20 nm was evaporated on the surface of the Al and MgF2 coatings.According to changes of the substrate temperatures at the room temperature,100,200 and 300℃,the effects of the substrate temperatures on the mirror reflectivity were researched.The results measured by a vacuum ultraviolet reflector show that improving the substrate temperature after evaporating MgF2 is in favour of increasing the reflectivity of Al/MgF2 mirror and the thickness of the Al/MgF2 is related to the reflectivity of the mirror.When the thickness of MgF2 is 26.7nm,the reflectivity at 122 nm is about 85%.The reflectivity of the mirrors stored in the laboratory is barely changed after one monthand five months.The results provide technological function for higher performance optical elements in vacuum ultraviolet optical systems.