Characterization of far-infrared optical thin film materials and blends: AgBr AgCl KBr Csl and CsBr

摘要

The selection of thin film materials for use in far infrared filters is limited. While silicon can be used as a high index material in the far infrared, the suitability of low index materials is less understood. In this study, thin film materials with spectral transmission extending from 1 to beyond 30 micrometer are characterized and evaluated for use in Rugate and discrete interference filters. A materials selection matrix was developed, and five materials were selected for characterization. Transmission, reflection and absorption data are presented for AgBr, AgCl, KBr, CsI and CsBr as single material films, and as blends. These materials are characterized for stress, exposure to humidity, and color center formation when exposed to visible light.