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Knight Optical(UK) Ltd - [email protected] - +44 (0)1622 859444


What are you looking for in Custom?

Germanium (Ge) is a relatively hard, high-density, IR transmitting material that blocks UV and VIS wavelengths but allows IR from 2µm. Germanium has the highest refractive index of commonly available IR-transmitters and has low optical dispersion. This makes it desirable in aspects of lens design where its refractive index allows otherwise impossible specifications to be built. AR coating is recommended.

Germanium transmits over 45% between 2-14μm up to 45⁰C but transmission degrades slowly at 100⁰C then more rapidly above 200⁰C. Exposure to higher temperatures can lead to catastrophic failure in the material so Germanium is unsuitable for use in these conditions. Additionally, its relatively high density should be considered where weight is an issue. Germanium has a hardness of HK780, slightly higher than GaAs with which it shares similar mechanical properties.

Typical applications for Germanium include thermal imaging where the material can be used as a front optic while its index of refraction makes Germanium useful for wide-angle lenses and microscopes. Additionally, Germanium components can be used for FLIR (Forward Looking Infra-Red) and FTIR (Fourier Transform Infra-Red) systems, alongside other analytical instruments.

Knight Optical supply custom windows, Custom Germanium lenses, Custom Germanium Prisms, and Germanium blanks to your specification for a range of applications. Every component is individually tested by our highly skilled technicians in our state of the art metrology lab to ensure all components meet our high quality standards.

Contact our multilingual technical sales team and discover how Knight Optical’s high quality Germanium optical components and service can improve your instrumentation and supply chain experience.


Thermal imaging cameras germanium optics

View germanium stock - click here

List of the Ge Windows always available 

Diameter (mm) Size (mm) Thickness (mm) Coated/Uncoated
5.00 n/a 0.50 Uncoated
5.90 n/a 0.50 Uncoated
11.50 n/a 1.00 Uncoated
12.50 n/a 1.00 Uncoated
12.70 n/a 1.00 Uncoated
12.70 n/a 2.00 Uncoated
12.70 n/a 3.00 Uncoated
13.00 n/a 1.00 Uncoated
25.40 n/a 0.50 Uncoated
25.40 n/a 1.00 Uncoated
25.40 n/a 1.50 Uncoated
25.40 n/a 3.00 Uncoated
25.40 n/a 3.00 Uncoated
40.00 n/a 2.00 Uncoated
45.00 n/a 3.00 Uncoated
50.00 n/a 1.00 Uncoated
50.00 n/a 2.00 Uncoated
50.00 n/a 3.00 Uncoated
50.00 n/a 4.00 Uncoated
50.00 n/a 5.00 Uncoated
50.00 n/a 10.00 Uncoated
54.00 n/a 3.00 Uncoated
57.00 n/a 2.50 Uncoated
65.00 n/a 3.00 Uncoated
75.00 n/a 1.00 Uncoated
75.00 n/a 2.00 Uncoated
75.00 n/a 3.00 Uncoated
80.00 n/a 3.00 Uncoated
102.00 n/a 3.00 Uncoated
180.00 n/a 3.80 Uncoated
- 18 x 18 1.00 Uncoated
- 8 x 14.6 1.00 Uncoated
- 15 x 12.5 1.50 Uncoated
- 25 x 18 1.00 -
- 50 x 32 3.00 -


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Our Multi-Lingual Sales Team are here to help with your requirments:

UK +44 (0)1622 859444
UK +44 (0)1622 850614
UK +44 (0)1622 851078
+1 401 583 7846

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We are able to ship to most countries at good rates, please click here for more info.

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