Zinc selenide (ZnSe) is a crystalline material that has a wide transmission band from 0.6µm to 21µm, covering a portion of the visible spectrum up into the far infrared. Coupling this with its minimal absorption makes it an ideal substrate for optical components used in infrared applications such as thermal imaging and high-powered laser systems.

A primary application of zinc selenide components is within CO₂ laser systems due to its excellent transmission at the 10.6µm operating wavelength and the low bulk loss it exhibits. Another advantage of using ZnSe is its transmission within the visible region, specifically 632.8nm. This allows for the HeNe laser pairing for alignment purposes.

The different zinc selenide optical components used in CO₂ lasers are typically:

• Focussing lens, generally a plano-convex lens.
• Lenses for beam expanders
• Protective windows
• Brewster windows, where the coating and angle the window is used at optimise the transmitted linearly polarised light.
• Beam combiners for when the CO2 laser is used in conjunction with a HeNe laser.

Zinc selenide is also commonly used is thermal imaging and FLIR applications due to its broad transmission range which encompasses the MWIR and LWIR thermal bands, for this reason it is also a popular material choice for ATR prisms used in FTIR spectroscopy.

Knight Optical has a stock catalogue of zinc selenide optical components including:

Zinc selenide windows which come in 7mm up to 70mm diameters, with options for an AR coating optimised at 10.6µm or 2-14µm, these have the following tolerances:

Zinc selenide lenses range from 5mm to 1-inch diameters, with coated and uncoated options. Below are their worked tolerances:

Here at Knight Optical we specialise in supplying our customers with bespoke zinc selenide optical components that are manufactured to your own specification. We can offer larger, or smaller, dimensions compared to our stock products, AR coatings to optimise the transmission over a certain waveband, DLC coatings to increase the durability of a surface, as well as manufacturing to other specifications you may require. Below are our typical manufacturing capabilities:

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 form error and radii, an Agilent Cary 660 FTIR for infrared transmission measurements and a Trioptics OptiSpheric for testing focal length.

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

UK, Europe, Asia & RoW: E-Mail info@knightoptical.co.uk  Tel +44 (0)1622 859444

USA & Canada: E-Mail usasales@knightoptical.com Tel +001 401-583-7846

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