Germanium Windows

12 Jan 2023

Germanium is a crystalline material which transmits within the infrared region, from 1.8 to 23µm, and has the highest refractive index of the commonly used infrared materials.

It’s transmission range makes germanium ideal for thermography applications, such as thermal imaging and gas detection, especially in the mid-wave (MWIR) and long-wave (LWIR) wavebands between 3 to 5µm and 8 to 12µm respectively.

Knight Optical can offer a range of germanium windows from our stock catalogue. Currently we can provide 10mm to 100mm diameters, with coated and uncoated options.

Our standard specifications for these germanium windows are:

Diameter: +0/-0.2mm
Thickness: ± 0.2mm
Flatness: < 1/10λ @ 10.6µm
Parallelism < 5’
Surface Quality: <60-40 scratch/dig

Our coated germanium windows have the following options:

• an AR/AR coating with a broadband wavelength range from 3-12µm, ideal for both MWIR and LWIR wavebands. This provides a transmission average of greater than 85%.
• An AR/DLC coating working between 7 to 14µm, ideal for LWIR applications. The diamond-like carbon (DLC) coating gives the coated surface additional durability which can be especially important if this surface is exposed to a harsh environment.

At Knight Optical, we excel at providing custom optics to our customers as we work with a multitude of companies working on bespoke projects requiring unique components. We can offer custom germanium windows, and other component types or materials, in dimensions up to 300mm plus. We can provide optimised AR and DLC coatings to suit your application.

With a metrology laboratory and dedicated QA department, Knight Optical test all optical components against their specification to ensure they meet all requirements, this includes a Zygo Verifire for checking surface error and an Agilent Cary 660 FTIR for infrared transmission measurements.

Contact our UK and US sales team for further information and help with your enquiries.

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