Materials>>Germanium windows and lenses
Germanium windows, Germanium lenses
Alkor Technologies - Russian manufacturer of Germanium windows and Germanium lenses. We offer quality IR Germanium windows and lenses for thermography and pyrometry at low price. Please, do not hesitate to contact us for pricing for any custom size and coatings requirements.
Maximum diameter of Germanium optics is 160mm. Anti-reflection BBAR coating (2-12µm and 8-12µm) and DLC coating can be applied for Germanium windows and lenses upon request.
Alkor is one of the largest Russian manufacturer of Germanium optics with 25 years experience. Germanium windows and lenses by Alkor are widely used in IR sensors, thermal image and medical applications, in pyrometry and thermography, FLIR cameras all over the world.
Germanium is used widely for lenses and windows in thermal imaging and FLIR applications. Its high index of refraction (about 4) makes it of particular interest. Useful transmission range of Germanium windows is from 2 to 13µm. Germanium is opaque in the visible.
Germanium transmission. Window thickness 10mm.
Germanium has the property of thermal runaway, meaning that the transmission decreases as temperature increases. As such, Germanium window should be used at temperatures below 100°C. The Knoop Hardness of Germanium (780) is approximately twice that of Magnesium Fluoride, making it ideal for IR applications requiring rugged optics. Germanium’s high density (5.33 g/cm^3) should be considered when designing for weight-sensitive systems.
Custom germanium lenses are available in any size and configuration. Anti-reflection and DLC coatings can be applied for 2-14µm or 8-14µm (BBAR coating) depending on your custom application.
Main properties:
| Chemical Formula | Ge |
| Crystal Form | Poly or Single Crystal |
| Crystal Class | Cubic |
| Lattice Constant, Е | 5.66 |
| Molecular Weight | 72.60 |
| Density, g/cm3 at 300 K | 5.33 |
| Dielectric Constant for 9.37 x 109 Hz at 300 K | 16.6 |
| Melting Temperature, K | 1210 |
| Thermal Conductivity, W/(m K) at 293 K | 59 |
| Thermal Expansion, 1/K at 298 K | 6.1 x 10-6 |
| Specific Heat, cal/(g K) at 273-373 K | 0.074 |
| Debye Temperature, K | 370 |
| Bandgap, eV | 0.67 |
| Solubility in water | None |
| Knoop Hardness, kg/mm2 | 800 |
| Mohs Hardness | 6.3 |
| Young's Modulus, GPa | 102.66 |
| Shear Modulus, GPa | 67.04 |
| Bulk Modulus, GPa | 77.86 |
| Poisson's Ratio | 0.278 |
Refractive Index Germanium (germanium index of refraction)
No = Ordinary Ray
| >µm | >No | >µm | >No | >µm | >No |
|---|---|---|---|---|---|
| 2.058 | 4.102 | 2.153 | 4.0919 | 2.313 | 4.0786 |
| 2.437 | 4.0708 | 2.577 | 4.0609 | 2.714 | 4.0562 |
| 2.998 | 4.0452 | 3.303 | 4.0369 | 4.258 | 4.0216 |
| 4.866 | 4.017 | 6.238 | 4.0094 | 8.660 | 4.0043 |
| 9.720 | 4.0034 | 11.04 | 4.0026 | 12.00 | 4.0023 |
| 13.02 | 4.0021 |