Abstract

Edge filter double-halfwave narrowband transmission filters and broadband antireflection coatings have been deposited employing a reactive ion plating process. Reactive ion plating is distinctly different from other ion-assisted deposition techniques in that a high-current low-voltage plasma arc burns into the vapor source rather than a low-current medium-to-high energy ion beam irradiating the substrate and growing film surface. The vapor sources are melts of metals or suboxides produced by a modified standard electron-beam gun. The optical substrates when coated by reactive ion plating are in contact with the plasma and attain a self-bias potential of –5 to –60 V, which accelerates the vapor atoms/molecules ionized by the plasma arc toward the substrate surface. The resulting coatings have a very dense microstructure as apparent from high-resolution transmission electron micrographs, obtained by direct sectioning of the coatings perpendicular to their surface with a microtome, and by replicating fractured edges with a platinum/carbon preshadowed carbon film.

© 1987 Optical Society of America