Optical crystal is used as the crystal material of optical medium material. It is mainly used for making windows, lenses and prisms in ultraviolet and infrared regions. According to the crystal structure, it can be divided into single crystal and polycrystalline.

Barium fluoride can be used to make motor brush, optical glass, optical fiber, laser generator, flux, coating enamel, as well as wood preservative and insecticide. Used for making flux and enamel; used as body preservative and solid lubricant. BaF2 crystal is used as ultraviolet or infrared window and laser material.

Calcium fluoride is widely used. With the progress of science and technology, its application prospect is more and more broad. It is mainly used in metallurgy, chemical industry and building materials industry, followed by light industry, optics, sculpture and national defense industry.

[purpose] it is used for manufacturing ceramics and glass; flux of metallurgical magnesium metal; coating of lens and filter in optical instrument; fluorescent material of cathode ray screen; flux, etc.