Germanium (Ge) is used widely for lenses and windows in thermal imaging and FLIR applications. Its high index of refraction makes it of particular interest. The useful transmission range of Germanium windows is from 2 to 12 μ m. Germanium is opaque in the visible.
Germanium has the property of thermal runaway, meaning that the transmission decreases as temperature increases. As such, Ge window should be used at temperatures below 100°. The higher Knoop Hardness of Germanium (780) makes it ideal for IR applications requiring rugged optics. Germaniumundefineds high density (5.33g/cm3) should be considered when designing for weight-sensitive systems.
Material Properties:
| Material Type | N or P |
| Resistivity (Ohm/cm) | 4-50 |
| Thermal Conductivity (J/k.m.s) | 58.61 @ 293K |
| Thermal Expansion Coefficients (1/oC) | 6.1x10-6 @298K |
| Density (g/cm3) | 5.33 |
| Knoop Hardness (kg/nm2) | 780 |
| Absorption Coefficient | 3x10-2 @ 10600nm |
Casix can provide different dimension window, mirror, wedge at present.
Capability:
| Attribute | Commercial | High Precision |
| End-Faces Configuration | Flat | |
| Dimension Tolerance | ± 0.1mm | ± 0.01mm |
| Surface Quality | 40-20 scratch and dig | 10-5 scratch and dig |
| Flatness | λ/4 | λ/10 |
| Parallelism | 20" | 2" |
| Perpendicularity | 15' | 5' |
Detail Specifications:
| Type | Polishing Area | Roughness |
Thick Plate | ≤5x5mm | 1nm |
| 5x5 - 8x8mm | 1nm | |
| 8x8 - Φ 38mm | 1nm | |
Thin Plate | ≤5x5mm | 1nm |
| 5x5 - 8x8mm | 1nm | |
| 8x8 - ≤ Φ 38mm | 1nm |
