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Germanium Windows / Substrates

Germanium is an excellent broadband Infrared (IR) window and substrate material. It has transmittance from 2.0 microns to 25 microns and with AR coatings has transmittance of an average of 70% and a peak of 92%.
  • Transmittance from 2.0 μm to 25 μm
  • Thickness: from 1 to 10 mm
  • Dimensions up to 160 mm

Thermal properties:
Thermal  Expansion  5.9 x 10-6 °C -1 @ 300K
Melting Point 937°C
Thermal diffusivity  0.36 cm2s-1
Thermal conductivity 0.58 W cm-1 °C-1
Specific heat 0.31 J g-1 °C-1
Mechanical properties:
Young Modulus  10.3x1011 dyn cm-2 @ 300K
Shear Modulus 4.1x 1011 dyn cm-2
Knoop Hardness  780 kg mm-2
Poisson constant 0.26
Electrical properties:
Di-electric constant  16.2
Resisitivity 9.0 ohm cm
Optical properties:
Transmission  2 - 14μm fino a circa 45°
Refractive Index  4.025 @ 4μm
4.005 @ 10μm