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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 Expansion5.9 x 10-6 °C -1 @ 300K
Melting Point937°C
Thermal diffusivity0.36 cm2s-1
Thermal conductivity0.58 W cm-1 °C-1
Specific heat0.31 J g-1 °C-1
Mechanical Properties:
Young Modulus10.3x1011 dyn cm-2 @ 300K
Shear Modulus4.1x 1011 dyn cm-2
Knoop Hardness780 kg mm-2
Poisson constant0.26
Electrical Properties:
Di-electric constant16.2
Resisitivity9.0 ohm cm
Optical Properties:
Transmission2 - 14μm fino a circa 45°
Refractive Index
4.025 @ 4μm
4.005 @ 10μm

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