Germanium Lens(Ge lens) for Infrared Applications

Germanium Lens(Ge lens) for Infrared Applications

Wavelength infrared provides germanium lens in popular sizes from 10m m to 200 mm in diameter. Lens size over 200mm could also be provided but considering the high density of germanium material, it would be too heavy for common infrared systems. Our standard AR and DLC coating are best suited for band in 3-5 or 8-12 micron. The focal length of our lenses would be controled to up to +/-1% tolerance, surface flatness λ/4 @ 632.8nm and surface irregularity less than 0.5 micron.

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Germanium lens is optical lens made of germanium. Germanium (Ge) is a crystalline material with the highest refractive index (4.002@11µm) of the commonly used infrared materials. It also has a comparatively low dispersion, high hardness and density. Due to its broad transmission range (over 45% in the 2-12 micron band) and opaque to the UV and visible light, Germanium is well suited for IR application such as thermal imaging systems, infrared field applications and precision analytic instruments.

Germanium is also subject to thermal runaway. With temperature growing, the absorption increases very rapidly. Because of this thermal runaway effect, germanium lens is not suitable to be used at temperatures above 100°C.

Wavelength Infrared can manufacture a variety shape of germanium lens with plane, concave, convex, aspheric and diffractive surfaces. Germanium is most popular for systems operating in the 3-5 or 8-12µm spectral region, with anti-reflective coatings (AR coating), the average transmission could be brought up to 97.5-98.5% depend on the bandwidth of the coating. We can also apply diamond-like carbon coating (DLC coating) or high durable coating (HD coating) on lens surface to provide extra protection against scratch and impact.

Wavelength infrared manufactures quality custom spherical and aspheric germanium lens. They can either focus or diverge incoming light beam to meet specific requirement of the infrared system. The application could be thermal imaging, thermograph, beam collimating, spectrum analysis and etc.


Material Germanium(Ge)
Diameter 10mm-300mm
Shape Spherical or Aspheric
Focal length <+/-1%
Decentration <1’
Surface figure <λ/4 @ 632.8nm (Spherical surface)
Surface irregularity < 0.5 micron (Aspheric surface)
Clear Aperture >90%
Coating AR,DLC or HD


1.DLC/AR or HD/AR coatings are available upon request.

2.Customization available for this product to suit your technical requirements. Let us know your required specifications.

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    Wavelength has been focused on providing high precision optical products for 20 years