ALKOR Technologies - your CRYSTAL optics supplier.   ALKOR Technologies - your CRYSTAL optics supplier.
ALKOR Technologies - your CRYSTAL optics supplier.
Materials>>Germanium windows and lenses

Germanium windows, Germanium lenses

Manufacturer of Germanium windows and Germanium lenses for Thermal Imaging Applications and Infrared Spectroscopy, custom Germanium optics.

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Contact Sales Team for pricing for custom size and coatings requirements. We offer very competitive prices on Germanium optics! Check now!

Germanium lenses

Alkor is one of the largest manufacturers of Germanium optics with 25 years experience. Our Germanium windows, wedges and lenses are widely used in IR sensors, LIDARs, thermal image and medical applications, in pyrometry and thermography, IR cameras all over the world.

Germanium transmission curve.

Uncoated Germanium transmission curve. Window thickness 10mm.

Germanium is used widely for lenses and windows in thermal imaging, FLIR applications, as germanium viewports. Its high index of refraction (about 4) makes it of particular interest

Useful transmission range of Germanium windows is from 2 to 13m. 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 100C.

The Knoop Hardness of Germanium (780) is approximately twice that of Magnesium Fluoride, making it ideal for IR applications requiring rugged optics. Germaniums 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 2-14m, 3-5m, 8-12m (BBAR coating or DLC/AR) depending on your custom application. Ask managers for transmission curves.

Germanium AR coating 8-14 microns.

AR/AR coating for 8-12microns.

Germanium AR coating 3-12 microns.

AR/AR coating for 3-12microns.

Germanium properties
Chemical Formula Ge
Crystal Form Monocrystal, orientation <111>, N-type
Crystal Class Cubic
Resistivity, Ohm*cm 5-40
Lattice Constant, 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

m No m No m 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

See Also: Silicon optics; ZnSe optics