Patent — available for licensing
High-Performance Aluminum Mirrors for Far-Ultraviolet Applications
A NASA invention available to explore as a licensing opportunity.
About this technology
Overview
Aluminum (Al) is known for its high reflectance in the 90 – 2500 nm wavelengths and is commonly used for mirrors in optical applications within this range e.g., for NASA’s proposed Large UV/Optical/IR (LUVOIR) surveyor observatory. However, in order to be used in the far-ultraviolet (FUV) spectral range between 90 – 130 nm, an optical thin film overcoat is needed to protect the Al and prevent the formation of an Al2O3 layer, which occurs upon exposure to oxygen. Lithium fluoride (LiF) has been a long-standing solution for this purpose, particularly for wavelengths below 120 nm. LiF coatings are opaque between 90 – 102 nm and even generate residual absorption above 102 nm, limiting reflectance at these short wavelengths. LiF coatings also suffer from hygroscopic degradation, leading to a reduction in reflectivity over time when exposed to humid environments. To address these challenges, innovators at NASA Goddard Space Flight Center have developed an advanced method to produce Al mirrors protected with a LiF overcoat using a novel room-temperature reactive Physical Vapor Deposition (rPVD) process. This method introduces a fluorine-containing xenon di-fluoride (XeF2) gas treatment that enhances the durability and stability of the LiF coating while achieving record-high reflectivity levels in the FUV spectrum.