Highly durable first surface silver based optical coatings and method of making the same

Abstract

A highly durable, environmentally and thermally stable Silver coating for mirrors, Infrared thin-film filters, or other optical coatings having very high reflection values over a large spectral and angular range where the enhanced durability and thermal stability are achieved through the selection and layer sequence of materials, which provide good chemical and environmental protection to Silver. Of particular importance are the layers directly below the Silver, and directly above the Silver (nucleation layer and barrier layer). It is important that the materials of those two layers provide diffusion barriers for Oxygen, water vapour and other corrosive gases, and are compatible in such a way that the layer below the Silver provides a good nucleation bed for Silver assuring that Silver will grow dense and highly reflective, and in some cases, when deposited in very thin layers, highly transparent in the visible spectrum, and the material of the layer directly above the Silver layer has to be compatible with Silver in a sense that it grows dense on the top of Silver, does not reduce the reflectivity of Silver, and also provides a good nucleation layer for the next layer being deposited.