CaF2
Properties:
| Crystal structure | cubic |
| Lattice | a=5.462 |
| Density | 3.18 g/cm3 |
| Transmission Range | 170 nm~7800 nm |
| Melting Point | 1360°C |
| Thermal Conductivity | 9.71W/m/K |
| Thermal Expansion Coefficient | 18.85X10 -6 /K |
| Mohs Hardness | 6 |
| Refractive Index | 1.6921mm - 1.3161mm |
| Diameter | +/-0.0, -0.1mm |
| Flatness | better than λ per 25 @633nm |
| Scratch-Dig | 80-50 per MIL-O-13830A |
| Wavefront Distortion | less than l /2 per inch @1064nm |