Zinc selenide (ZnSe) Optical Components

02 Nov 2021

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 (FIR). Coupling this with its minimal absorption makes it an ideal substrate for optical components used in infrared (IR) applications, such as thermal imaging and high-powered laser systems.

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

Different ZnSe optics used in CO2 lasers are typically:

• Focusing Lenses, generally the Planoconvex variety
• Lenses for Beam Expanders
• Protective Windows
• Brewster Windows, where the coating and angle of the optic is used to optimise the transmitted linearly polarised light
• Beam Combiners for when a CO2 laser is used in conjunction with a HeNe laser.

The material is also commonly used in thermal imaging and forward-looking infrared (FLIR) applications due to its broad transmission range, encompassing the mid-wave infrared (MWIR) and long-wave infrared (LWIR) thermal bands. For this reason, it is also a popular material choice for Attenuated Total Reflection (ATR) Prisms used in fourier-transform infrared spectroscopy (FTIR).

Here at Knight Optical, we have a wide-ranging stock catalogue of ZnSe optical components, including:

ZnSe Windows

Windows from 7mm to 70mm diameters, with options for an Antireflective (AR) coating optimised at 10.6µm or 2-14µm.

These have the following tolerances:

• Diameter: +0/-0.2mm
• Thickness: ± 0.2mm
• Surface quality: <60-40 scratch/dig

ZnSe Lenses

Our Lenses range from 5mm to 1-inch diameters, with coated and uncoated options.

Below are their worked tolerances:

• Diameter: ±0.2mm
• Thickness: ± 0.2mm
• ROC: Nominal
• Edge thickness: ± 0.2mm
• Centre thickness: ± 0.2mm
• Surface quality: <60-40 scratch/dig

Bespoke ZnSe Optical Components

We also specialise in supplying bespoke ZnSe optics that are manufactured to your own specification. We can offer large and small dimensions, AR coatings to optimise the transmission over a specific waveband, Diamond-Like Carbon (DLC) coatings to increase the durability of a surface, as well as manufacturing to other specifications you may require.

Our typical manufacturing capabilities comprise:

• Diameter: < 5mm to 100mm +
• Form error: (@633nm): < 1 wave
• Centration/parallelism: < 3 arcminutes
• Scratch/dig: < 60/40
• Typical coatings: Single-sided BBAR @2-14µm

Metrology Tested & Quality Assured

With a state-of-the-art Metrology Laboratory and dedicated QA Department, Knight Optical tests all optical components against their specifications to ensure they meet all requirements. This includes a Zygo Verifire for checking surface form error and radii, an Agilent Cary 660 FTIR for IR transmission measurements and a Trioptics OptiSpheric for testing focal length.

Contact our UK and USA sales teams for further information and assistance with your enquiries.

www.knightoptical.com

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

USA & Canada: usasales@knightoptical.com +1 401-583-7846