Enhanced MgFsub2/sub and LiF over-coated Al mirrors for FUV space astronomy

摘要

Astronomical observations in the far--ultraviolet (FUV) spectral region are some of the more challenging due tothe very distant and faint objects that are typically searched for in cosmic origin studies such as origin of largescale structure, the formation, evolution, and age of galaxies and the origin of stellar and planetary systems.The problem is compounded by the very limited option of reflecting coatings to use at FUV wavelengths andthe modest reflectivity offered by those coatings such as Al+MgFsub2/sub [typically 82 % at Lyman-alpha, 1216 Α)that are used on reflecting surfaces of FUV instrumentation. Improved reflective coatings for optics, particularlyin the ultraviolet part of the spectrum, could yield dramatically more sensitive instruments and permit moreinstrument design freedom.This paper will present recent advances in reflectance performance for Al+MgFsub2/sub mirrors optimized for Lymanalphawavelength by comparing an ambient or ”cold” deposition with another where the deposition temperaturefor the MgFsub2/sub layer is done at elevated temperatures. We will also consider this improved procedure for thedeposition of LiF over-coated Al mirrors in order to realize similar reflectivity gains at even shorter wavelengths.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.