University of California Observatories has undertaken an effort to develop improved coatings for optical astronomy, both reflective and anti-reflective. We report of the latest developments in this program. This effort includes new interface materials between silver and protective over-layers, one of which (nickel oxide) shows great promise for enhanced durability and works well to λ~340nm, as shown by aggressive environmental stressing. In addition, we have been exploring atomic layer deposition (ALD) for building protective metal-oxide layers for silver-based coatings, using a new facility capable of coating optics up to 0.9-m in size. This new facility has just been delivered, but we have already obtained excellent uniformity with Al2O3 coatings across the full diameter. We are exploring different deposition parameters with the goal of achieving excellent thin films at lower temperature than typically used in ALD by employing both remote plasma enhancement and/or alternate oxidizing agents. We plan to explore nitride and fluorides also. Finally, we report on continued development and deposition of broad-band anti-reflection coatings based on silica sol-gel. These developments are particularly important with regards to the next generation telescopes and instruments, but of course could be applied to existing telescopes and instruments.
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