Optical and mechanical characteristics of mixed composition zinc telluride-magnesium fluoride optical thin films for use in the near infrared region

Mixed composition optical thin films pf zinc telluride-magnesium fluoride, which have not been studied so far, have been investigated. These films hav e been evaporated by thermal evaporation from mixtures of the constituents in different proportions by weight, from a single source. The films have be en characterised for their optical properties (refractive index, extinction coefficient and IR transmittance), mechanical properties (intrinsic stress and surface morphology) and crystalline/amorphous structure. It has been f ound that these mixed composition films have tailorable refractive indices and low intrinsic stress for a certain range of compositions. Good IR trans mittance and smooth surface morphology are the general features of these fi lms. This makes them useful for incorporation in multilayer thin film optic al coatings in the near infrared region.