Specifications:
| Materials | BaF2 crystals | Diameter Range | ~200mm |
| Diameter Tolerance | +0.0/-0.2mm | Thickness Tolerance | +/-0.1mm |
| Surface Quality | 60/40 S/D | Fringes (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 Lenses or BaF2 Lenses are excellent for light direction and manipulation in the ultraviolet, visible, and infrared spectral regions with a high transmission rate above 90% between 0.25 and 9.5µm. Barium Fluoride Shares similar properties with CaF2, with the advantage that BaF2 is more resistant to high-energy radiation. Nonetheless, BaF2 is half as hard as CaF2, and its transmission is more susceptible to temperature change (this is in particular true in humid environments because BaF2 is not stable under exposure to water). Barium Fluoride lenses are often used in thermal cameras integrated with a cryogenic cooler, Hangzhou Shalom EO offers the BaF2 lenses used in MWIR (3-5 micro) thermal imaging applications.
Curves:
Transmission Curves of BaF2 Substrates of Different Thicknesses
