Calcium Fluoride and Barium Fluoride Crystals in Optics

Calcium fluoride has a long tradition as an optical material in microlithography for semiconductor production. Based on the limited choice of optical materials transmitting well in the deep UV wavelength range, calcium fluoride could establish as an industry standard material for excimer laser optics in projection and illumination optical designs for the microlithography process. But beyond the UV, calcium fluoride and barium fluoride crystals also exhibit an excellent broadband transmittance and feature unique optical properties. These open up a variety of advanced applications covering the full visible range up to the mid‐infrared wavelength range.