Polymer Barrier, Protection and Cleaning for UVOIR and X-Ray Mirrors

Maturing vacuum ultraviolet mirror coating technology for use in UV Astrophysics is on the critical path for NASA Flagship Missions such as the Habitable Worlds Observatory (HWO). In the Lyman Ultraviolet (LUV ~90-122nm), the reflection efficiency of current telescope mirror coatings drops precipitously. The best option, bare aluminum, forms a natural oxide coating in seconds and absorbs these wavelengths. One solution would be to fabricate the telescopes and mirrors in the vacuum of space to avoid oxygen. Recently, excellent progress has been made utilizing lithium and aluminum fluorides as protective and reflectivity-enhancing coatings on aluminum. However, these materials are easily scratched and must be protected from water vapor intrusion in assembly, testing, and while waiting for launch. This proposal suggests creating a family of removable polymer film coatings as water barriers and cleaners for water-sensitive and freeform optical surfaces. The Apply-Dry-Peel-No-Residue polymer coatings developed herein will also reduce or eliminate pinholes when used to clean and prepare the surface before depositing the aluminum mirror and fluoride overcoats-enhancing coating performance, longevity, and enhancing stray-light suppression. The nearly ubiquitous pinholes that occur in fabricating metal coatings lead to corrosion, light scattering, and coating failure. This technology will mitigate NASA's mission risk by enabling the cleaning of historically uncleanable surfaces and by pre-qualifying the safety of cleaning flight optics early in missions. Avoiding irreversible failures when contamination happens will save time and money. Without such pre-clearance, precision mission surfaces might have to, again, launch dirty or with a fingerprint, as with HST's primary mirror and the Wide Field Camera II. Indeed, Hubble's primary mirror had a 10% degradation in reflectivity due to pre-launch contamination.