Anti-Reflection Coated Germanium Windows

We supply a wide range of anti-reflection coated germanium windows in a variety of shapes and sizes, both off the shelf and custom-made for your exact requirements.

Germanium (Ge) is a hard, high-density, IR transmitting material that blocks UV (ultraviolet) and VIS (visible) wavelengths but allows IR from 2µm. Germanium has the highest  RI (refractive index) of commonly available IR-transmitters and has low optical dispersion.

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 not suited for use in these conditions.  Where weight is an issue, its relatively high density (5.327gm/cc) should be considered .

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 Infrared) and FTIR (Fourier Transformed Infrared) spectroscopy systems, alongside other analytical instruments.

Our stock  Germanium windows are available for worldwide shipping today .Please contact our sales team for advice and to help you select the best windows for your application. 

Our windows include 50mm x 3mm AR DLC coated Germanium Windows, 75mm x 3mm AR DLC coated Germanium Windows and 100mm x 6mm AR DLC coated Germanium Windows.  See below for full specifications and details on how to order.

NOTE: Items ending with SO are special order and might not be available immediately from stock. Please contact us to check

Specific coatings applied to stock items are listed below 

Custom coatings for Germanium windows available on request

New STOCK sizes now added