Germanium – Ge

lenses, windows, mirrors, filters and prisms


A Germanium lens has a high refractive index making it essential to add anti-reflection coating to improve its transmission. The transmission of Germanium lenses and windows is highly sensitive to temperatures that are above 70°C becoming opaque. Germanium has a rugged appearance and is especially durable making it suitable for external Infrared applications.

A Germanium window is highly efficient, in fact, it’s so efficient you could take a photo using the lens – our Germanium lenses are most commonly used to focus infrared light and can be used for camera lenses.

If you’re looking for a Germanium glass, you can rest assured that our products will provide you with the best value for money because they have a high precision rate and can be customised to suit your needs specifically.


Transmission Range 1.8 – 23.0 µ
Crystal Structure Diamond
Cleavage Plane 111
Colour Metalic lustre
Density 5.327 (25°)
Melting Point (°) 942
Reflection Loss 52.9% (10µ) for 2 surfaces
Solubility index Insoluble
Hardness (Knoop) 692
Thermal Conductivity (cal/cm sec°C) 0.14 (20°C)
Thermal Expansion coefficient (/°C) 5.5x10-6(25°C)

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