| |
 |
|
|
| Basic Properties |
| Crystal structure | Hexagonal System | Cubic | cubic |
| Lattice | a=4.785, C=12.991 | | a=5.462 |
| Density | 3.98g/cm3 | 4.5g/cm3 | 3.18 g/cm3 |
| Transmission Range | 150~5500nm | 250~5000nm | 170 nm~7800 nm |
| Melting Point | 2040 °C | 1970 °C | 1360 °C |
| Specific Heat | 0.418 W.s/g/K | 0.59 W.s/g/K | |
| Thermal Conductivity | 25.12 W/m/K | 14 W/m/K | 9.71W/m/K |
| Thermal Shock Resistance | 790 W/m | 790 W/m | |
| Thermal Expansion Coefficient | 5.8x10-6 /K | 6.9x10-6 /K | 18.85X10-6 /K |
| dn/dt, @633nm | 13x10-6 /K | 7.3x10-6 /K -1 | |
| Mohs Hardness | 9 | 8.5 | 6 |
| Refractive Index | 1.83 @0.26 mm, 1.76 @0.63 mm,1.58 @5.57 mm | 1.8245 @0.8 mm 1.8197 @1.0 mm 1.8121 @1.4 mm | 1.6921mm - 1.3161mm |
| Specifications of Windows and Mirrors |
| Diameter | +/-0.0, -0.1mm | +/-0.1mm | +/-0.0, -0.1mm |
| Thickness | +/-0.2mm | +/-0.2mm | +/-0.2mm |
| Flatness | better than λ per 25 @633nm | better than λ/8@633nm | better than λ per 25 @633nm |
| Parallelism | better than 3' | better than 30'' | better than 3' |
| Perpendicularity | better than 5' | better than 5' | better than 5' |
| Scratch-Dig | 80-50 per MIL-O-13830A | 10-5 per MIL-O-1383A | 80-50 per MIL-O-13830A |
| Wavefront Distortion | less than l /2 per inch @1064nm | better than l /2 per inch@1064nm | less than l /2 per inch @1064nm |
