Abstract

Many metal fluorides are stable in adverse environments and some are used as coatings for optical components. In general, these materials have low refractive indices and are therefore of use as the low index component in multilayer AR or HR coatings or, in some cases, notably MgF₂, as the single component in simple 1/4 wave AR coatings. These coatings are normally prepared by evaporation or sputtering and as such are substantially dense and therefore of an index close to that of the bulk fluoride material. This is quite satisfactory for multi-layer application but is inefficient in 1/4 wave AR coatings on typical substrates of index about 1.5 because the index is too high.

© 1987 Optical Society of America