Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2016 · 14 citations · 11 references
Natural SciencesMaterials EngineeringMaterials ScienceSurface EngineeringSurface ScienceThin FilmsAtomic Layer DepositionCoating ProcessesCoating TechnologyCoatingsPhysical Vapor DepositionSurface CoatingsCoating DurabilityCoating Durability TestingCoating TestingDeposition ProcessesEnvironmental Durability Of CoatingsNitrides Thin FilmsOptical CoatingsPhysical Vapor Deposition Coatings
We present progress in efforts underway at the University of California Observatories to develop high performance durable silver-based mirror coatings for telescope and instruments. Silver-based coatings are extremely prone to tarnish and/or corrosion, and successful coatings depend not only on the materials used but also the deposition processes employed. Our physical vapor deposition (PVD) chamber allows both sputtering and ion-assisted e-beam depositions for head-to-head comparison of deposition processes, and we present results of these comparisons. In this paper, we review the problem and discuss our recent activities and findings. We discuss a systematic study to determine which oxides, nitrides and fluorides provide the best protection in environmental tests. We present initial results into the effects of stress in our specific thin films, and thee effects of stress on mirror coating durability. We also discuss studies using Atomic Layer Deposition (ALD) over-coating of Ag, and we describe a large ALD research chamber currently under construction that will demonstrate ALD processes on larger substrates (70 cm diameter).
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