Alkor Technologies - manufacturer of Germanium windows and Germanium lenses for thermography and pyrometry.
Alkor manufactures:
Please visit our new Germanium windows catalog and Germanium lenses catalog. Please do not hesitate to contact us for pricing for any custom size and coatings requirements.
Special prices on large diameter Ge optics!
See Also: Silicon optics; ZnSe optics
| Standard Specifications |
High Precision |
| Material |
Germanium optical monocrystal |
| Dimensions |
± 0.00/-0.10mm |
+0.00/-0.05 |
| Thickness |
± 0.10mm |
±0.05 |
| Surfaces |
60/40 |
20/10 |
| Edges |
Fine Ground |
| Flatness |
≤5 Fringes |
0.5 Fringes |
| Parallelism |
≤ 3 Arc mins |
30 arc seconds |
Alkor is one of the largest Russian manufacturer of Germanium optics with 20 years experience. Germanium windows and lenses by Alkor are widely used in IR sensors, LIDARs, thermal image and medical applications, in pyrometry and thermography, FLIR cameras all over the world.
Germanium transmission. Window thickness 10mm.
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 13mkm. Germanium is opaque in the visible. 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 windows and germanium lenses are available in any size and configuration. Anti-reflection coatings can be applied for 2-14mkm or 8-12mkm (BBAR coating or DLC/BBAR) depending on your custom application.
Material characteristics measured at the producer |
| Parameters |
Mono |
Poly |
Method of measurement |
| Orientation |
[111]
+/-2o |
- |
GOST 16153, ASTM F 26
X-Ray Diffraction |
| Conductivity |
N |
N |
GOST 16153, ASTM F 42
Hot-Probe method |
| Dopant |
Sb |
Sb |
- |
| Resistivity *), Ohm*cm |
standard 5-40, other as agreed |
standard 5-40, other as agreed |
GOST 24392, ASTM F 43
Four-Probe,
Two-Probe |
| Transmission |
46% min in the range  =3-10  m through polished sample, 10 mm thick |
FTIR-Spectrometry ASTM F 120 |
| Germanium properties |
| Chemical Formula |
Ge |
| Crystal Form |
Poly or Single Crystal |
| Crystal Class |
Cubic |
| Lattice Constant, Å |
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 of Germanium |
| Wavelength, µm |
2.06 |
2.15 |
2.44 |
2.58 |
3.00 |
3.42 |
4.36 |
6.24 |
8.66 |
9.72 |
11.04 |
13.02 |
| Refractive Index |
4.10 |
4.09 |
4.07 |
4.06 |
4.05 |
4.03 |
4.02 |
4.01 |
4.00 |
4.00 |
4.00 |
4.00 |
|