Contamination-tolerant antireflection coating designs

Transparent spacecraft components, such as solar cell cover glass or optical lenses, are generally coated with an antireflection (AR) coating to minimize transmission losses. Accumulation of molecular contamination on these ARcoated surfaces can lead to significant performance degradation. While the current approach to maintaining optical performance is prevention of contamination, this work presents a new design paradigm in which the AR coating is designed to maintain performance while contaminated. Specifically, the contamination-tolerant AR (CTAR) design approach simultaneously optimizes for evolving levels of contamination over the lifetime of the surface. Traditional and CTAR coatings were designed and tested side-by-side, by vacuum-depositing silicone contamination with thicknesses up to 100 nm. The CTAR coatings outperformed traditional coatings for all levels of contamination, with transmission improving by as much as 3% (absolute). This positive proof-of-concept result demonstrates that a small tweak in coating design can deliver a substantial increase in the lifetime performance of an optic. CTAR designs can relax contamination budgets for spacecraft, which can significantly save on cost and schedule in addition to extending mission life. Moreover, this simultaneous, multi-state design approach is applicable to any systems with multiple operating conditions.