Germanium (Ge)

Germainium's transmission from 1.8um to 14um make it a popular material for IR applications such as thermal imaging. Ge's high density compared to other infrared materials make it useful in imaging systems where ruggedness and durability is important, and its fluorite counterparts would suffer damage.

Whilst Germanium's high index of refraction make it of particular interest for lens and prism designs, components are often AR coated to avoid losses.

Substance Form Diameter Range Thickness Range Transmission Range (µm) Typical Transmission
Germanium (Ge) Single or Poly Crystal 10mm - 400mm 3mm - 50mm 1.8 - 14.00 46% (2 - 14µm)

Material Properties

Transmission Range 1.8 - 24.0 microns
Density 5.32 g/cm3
Refractive Index 4.005 @ 8µm
Melting Point 938°C
Thermal Conductivity 59 W/Km @ 300K
Transmittance (2µm - 11µm) ˜ 46%
Crystal Structure Diamond Cubic
Electrical Resistivity 53 ohm-cm @ 25°C
Knopp Hardness 780
Thermal Shock Resistance 125°C