Specifications:
| Materials | CaF2 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 | 0.13 to 10 μm | Refractive Index | 1.39908 at 5 μm (1) (2) |
| Reflection Loss | 5.4% at 5 μm | Absorption Coefficient | 7.8 x 10-4 cm-1 @ 2.7 μm |
| Reststrahlen Peak | 35 μm | dn/dT | -10.6 x 10-6/°C (3) |
| dn/dμ = 0 | 1.7 μm | Density | 3.18 g/cc |
| Melting Point | 1360°C | Thermal Conductivity | 18.85 x 10-6/°C (5)(6) |
| Hardness | Knoop 158.3 (100) with 500g indenter | Specific Heat Capacity | 854 J Kg-1 K-1 |
| Dielectric Constant | 6.76 at 1MHz (7) | Youngs Modulus (E) | 75.8 GPa (7) |
| Shear Modulus (G) | 33.77 GPa (7) | Bulk Modulus (K) | 82.71 GPa (7) |
| Elastic Coefficients | C11 = 164 C12 = 53 C44 = 33.7 (7) | Apparent Elastic Limit | 36.54 MPa |
| Poisson Ratio | 0.26 | Solubility | 0.0017g/100g water at 20°C |
| Molecular Weight | 78.08 | Class/Structure | Cubic (111) cleavage |
Due to its high average transmission and low chromatic aberration relative to other IR materials, calcium fluoride (or CaF2 ) is an excellent choice for windows and lenses for spectroscopy applications in the deep UV to near IR wavelength range (180 nm-8 µm). For its good transmission properties at MWIR range, the CaF2 are often selected as the lenses for MWIR (3-5 micro)thermal imaging applications.
Curves:
Transmission curve of the CaF2 substrates of different thickness
