Calcium Fluoride (CaF2)

Calcium Fluoride can be used in the ultraviolet, visible and infrared spectral regions. Calcium Fluoride has a transmission above 90% between 0.25 and 7µm.

Calcium Fluoride is twice as hard as Barium Fluoride and also less susceptible to thermal shock. However, it is commonly used in cryogenically cooled thermal imaging systems. It is less expensive than Barium Fluoride. CaF2 is diamond turnable.

 

Property Specification
Transmission Range 0.13µm to 7.0µm
Density 3.18 g/cm3
Thermal Expansion 18.85 x 10-6 /°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.
Surface Figure In the UV & Visible spectral regions, surface figure ranges from 1/10 wave to 1/4 wave @ 0.6328µm. In the infrared, typical required surface figure ranges from 1/4 wave to 2 waves @ 0.6328 µm & are specified depending on the system performance requirements.
AR Coating Options Available coatings for CaF2 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, Microlithography, Excimer Laser applications.
Products Manufactured Lenses, Aspheric lenses, windows, Optical Beamsplitters, Optical Filters, Wedges, Prisms.

 

Wavelength µm)
Index of Refraction (n)
1.0600
1.428
2.0582
1.424
4.0000
1.410
5.8932
1.387
8.2505
1.344
9.4291
1.316