Barium Fluoride (BaF2)

Barium Fluoride can be used in the ultraviolet, visible and infrared spectral regions. Barium Fluoride has transmission above 90% between 0.25 and 9.5µm.

Barium Fluoride is half as hard as Calcium Fluoride and also more susceptible to thermal shock. However, it is commonly used in cryogenically cooled thermal imaging systems. It is somewhat more expensive than Calcium Fluoride and not as readily available in large sizes.

 

Property Specification
Transmission Range 0.15µm to 12.5µm
Density 4.89 g/cm3
Thermal Expansion 18.1×10-6 /°C @ 20°C+/-100°C
Surface Finish Polishes of 20-10 scratch-dig are mostly specified for use in UV & visible applications. Typical specifications for surface quality in the infrared are a 40-20 scratch dig in the 0.75 to 3µm spectral region & 60-40 scratch-dig for the 3-7µm area. BaF2 is diamond tunable.
Surface Figure Surface figure of a 1/10 wave to 1/2 wave @ 0.6328µm are specified mostly on lenses for ultraviolet & visible use. In the infrared, typical required surface figure ranges from 1/2 wave to 2 waves 0.6328µm depending on the system performance requirements.
AR Coating Options Typical available coatings for BaF2 include BBAR for 0.8 to 2.5µm, 3 to 5µm or the 1 to 5µm spectral regions.
Typical
Applications
Cryogenically cooled thermal imaging, Astronomical, Laser applications.
Products Manufactured Lenses, Aspheric lenses, Windows, Optical Beamsplitters, Optical Filters, Wedges, Prisms.

 

Wavelength (µm)
Index of Refraction (n)
1.700
1.466
2.152
1.464
3.422
1.459
4.000
1.455
6.238
1.442
7.268
1.433
10.346
1.396