Specifications:
| Materials | BaF2 crystals | Diameter Range | ~200mm |
| Diameter Tolerance | +0.0/-0.2mm | Thickness Tolerance | +/-0.1mm |
| Surface Quality | 60/40 S/D | Frings (N) | 3 |
| Irregularity (delta N) | 1 | Centration | 3' |
| Chamfer | 0.1-0.3mmx45 degree | Coatings | AR/AR@3-5micro |
Physical and Optical Properties:
| Transmission Range | 0.15 to 12 μm | Refractive Index | 1.45 at 5 μm (1) |
| Reflection Loss | 6.5% at 5 μm (2 surfaces) | Absorption Coefficient | 3.2 x 10-4 cm-1 @ 6 μm |
| Reststrahlen Peak | 47 μm | dn/dT | -15.2 x 10-6 /°C (2) |
| dn/dμ = 0 | 1.95 μm | Density | 4.89 g/cc |
| Melting Point | 1386°C | Thermal Conductivity | 11.72 W m-1 K-1 @ 286 K |
| Thermal Expansion | 18.1 x 10-6 /°C @ 273 K | Hardness | Knoop 82 with 500g indenter (4) |
| Specific Heat Capacity | 410 J Kg-1 K-1 (3) | Dielectric Constant | 7.33 at 1 MHz |
| Youngs Modulus (E) | 53.07 GPa (3) | Shear Modulus (G) | 25.4 GPa (3) |
| Bulk Modulus (K) | 56.4 GPa | Elastic Coefficients | C11 = 89.2 C12 = 40.0 C44 = 25.4 (2) |
| Apparent Elastic Limit | 26.9 MPa (300psi) (4) | Poisson Ratio | 0.343 |
| Solubility | 0.17g/100g water at 23°C | Molecular Weight | 175.36 |
| Class/Structure | Cubic CaF2, Fm3m, (111) cleavage |
Barium Fluoride or BaF2 crystals could be used in the ultraviolet, visible and infrared spectral regions. BaF2 has a good 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, Hangzhou Shalom EO offer the BaF2 lenses used in MWIR (3-5 micro) thermal imaging applications.
Curves:
Transmission curve of the BaF2 substrates of different thickness
