Barium Fluoride is used in spectroscopic components. Barium Fluoride is often suitable for applications in the passive IR band (8 to 14 μm) and is often used as a viewport window for thermography. For an equivalent thickness the transmission extends approximately 1 micron further into the IR than Calcium Fluoride. Windows intended primarily for IR use and noted as having IR polish may have restricted transmission in the VUV being made from lower purity BaF2 crystal.
The highest quality Barium Fluoride also has application as the fastest known scintillator material and is used in High Energy Physics Experiments.