Potassium Bromide (KBr) is commonly used for optical components in expanded spectrum band from the near ultraviolet to long wave infrared regions, since it is transparent over an extremely wide range of wavelengths (about 0.25 µm to 26 µm).
Potassium Bromide has refractive index about 1.55 at 1.0 µm and no significant optical absorption lines in its high transmission region.
Potassium Bromide can be used at temperatures up to 300 °C. The material cleaves readily, its irradiation produces color centers.
Potassium Bromide is hygroscopic and highly soluble in water. That's why it must be kept in a dry environment or protected against moisture degradation of polished surfaces. The material can be polished to a high standard under humidity controlled conditions.
Potassium Bromide is used for optical windows, lenses, prisms and other optical items in the range from the ultraviolet to the infrared. It is one of the most useful materials for IR spectroscopic components and beamsplitter for CO2 -lasers.