1. Wide spectral transmission range
Calcium fluoride (CaF₂): The transmission band is 0.15-6 µm, covering the ultraviolet to infrared spectrum.
Barium fluoride (BaF₂): The transmission band is 0.15-12 µm, especially suitable for infrared applications, and has a wider infrared transmission than calcium fluoride at the same thickness.
Lithium fluoride (LiF): The transmission band is 0.11-7.5 µm, especially in the deep ultraviolet (VUV) region.
2. Optical performance
High transmittance: Fluoride crystals have high transmittance in the infrared band, for example, the transmittance of calcium fluoride in the infrared region can reach more than 85%.
Low refractive index: The refractive index of calcium fluoride is about 1.43, which helps reduce reflection losses.
Low absorption rate: Barium fluoride has a low absorption coefficient in the infrared band (e. g., 3.2 × 10 in 6 µm), ensuring high energy transmission.
3. Physical and chemical properties
Chemical stability: Fluoride crystals have good chemical stability and can maintain optical properties in a variety of environments.
Thermal stability: Materials such as calcium fluoride and barium fluoride have a high melting point (for example, the melting point of calcium fluoride is 1418°C) and are suitable for high temperature environments.
4、Mechanical properties: fluoride crystal hardness is moderate, but it should be noted that barium fluoride is more sensitive to thermal shock.