Far-UV reflectance and stress of narrowband AlF₃/LaF₃ multilayers

Upcoming space instrumentation, such as LUMOS (LUVOIR Ultraviolet Multi-Object Spectrograph) in LUVOIR (Large Optical Infrared Surveyor) mission, demands efficient narrowband coatings centered the far UV (FUV). Narrowband FUV can be prepared with all-dielectric multilayers (MLs) based on two fluorides. This research evaluates performance of AlF 3 /LaF MLs by thermal evaporation and compares this MgF 2 MLs, which were previously investigated. reflectance, stress, influence substrate materials have been investigated, along ML stability over time when stored a desiccator. Coatings deposited both fused silica CaF crystals, common optical substrates. exhibited reduced stress compared resulting larger thickness threshold before crack generation. enables preparing more layers hence higher performance. underwent lower reflectance decay MLs. Fresh at ∼160 nm displayed peak close to 100%, most kept 99% after several months storage. The bandwidth for given number was found somewhat than