Zinc Selenide (ZnSe) is a versatile optical material known for its unique transmissive properties and applications, particularly in infrared (IR) optics and CO2 lasers. At Crystran we process Zinc Selenide material to create optical components that perform well in the visible to IR range. Optics produced from Zinc Selenide can also benefit greatly in some applications from surface coatings to increase transmission by limiting reflections.
This blog explores the unique characteristics of ZnSe and its vital role in various modern applications.
Properties of Zinc Selenide
ZnSe is favoured for its broad transmission range (0.6 to 21 microns) and low absorption at 10.6 microns, making it ideal for IR optics and CO2 laser systems. Key properties include:
- Refractive Index: 2.4028 at 10.6 microns
- Thermal Conductivity: 18 W m-1K-1 at 298 K
- Melting Point: 1525°C*
- Hardness: Knoop 120 with a 500g indenter
- Density: 5.27 g/cc
*(For ZnSe oxidation occurs significantly at 300°C within normal atmosphere and exhibits plastic deformation at around 700°C)
ZnSe is typically produced through the synthesis from zinc vapor and H2Se gas, resulting in a microcrystalline structure that offers high strength and durability.
At Crystran we utilise proprietary techniques to optimise the surface quality and surface figure specification of our Zinc Selenide optics leading to greatly improved performance compared to polishing with other traditional techniques.
General Applications in Infrared Optics
ZnSe is widely used in IR optical systems due to its excellent transmission and low absorption characteristics. These properties make it ideal for applications such as thermal imaging, FLIR (Forward-Looking Infrared) systems, and ATR (Attenuated Total Reflectance) prisms.
In thermal imaging, ZnSe lenses are used to capture and focus infrared radiation, converting it into visible images. These lenses are crucial for applications in night vision, security surveillance, and medical diagnostics, where high sensitivity and resolution are required.
Application of ZnSe in ATR Prisms
Attenuated Total Reflectance (ATR) spectroscopy is a powerful technique used in IR spectroscopy for analysing samples quickly and without specialist preparation. Zinc Selenide is a preferred material for ATR prisms due to its high refractive index and wide transmission range in the IR spectrum. In ATR spectroscopy, an IR beam is directed into the ZnSe prism and reflects internally, interacting with the sample placed on the prism surface. This interaction provides detailed molecular information about the composition of the sample.
A common use case for ZnSe ATR prisms is in the pharmaceutical industry, where they enable rapid and non-destructive analysis of drug formulations, ensuring quality and consistency in production.
Applications in CO2 Lasers
ZnSe is the preferred material for CO2 laser optics, designed to operate at a wavelength of 10.6 microns. Its low absorption and high thermal conductivity contribute to efficient performance and extended durability in high-power laser systems. A key advantage of ZnSe is its partial transparency in the visible spectrum, allowing the use of a red HeNe laser for convenient system alignment.
In the manufacturing industry, CO2 lasers equipped with ZnSe optics are employed for precise cutting and welding of materials. The high power and efficiency of these lasers make them ideal for processing metals, plastics, and composites with exceptional accuracy and speed.
Role of Optical Coatings
Optical coatings enhance the performance of ZnSe components by reducing reflection losses and improving transmission. The coatings vary based on the application:
- CO2 Lasers: Anti-reflective (AR) coatings tailored for 10.6 microns are used to maximize energy transmission and minimize losses, ensuring optimal laser performance and longevity.
- IR Optics: Broadband AR coatings are applied to ZnSe optics used in thermal imaging and spectroscopy to enhance transmission across a wide range of wavelengths, improving image quality and measurement accuracy.
Zinc Selenide's unique properties make it indispensable in specialist applications, particularly in IR optics and CO2 laser systems. Its ability to transmit a broad spectrum of IR radiation and its low absorption at critical wavelengths underscore its utility in high-performance optical systems. With the right optical coatings, ZnSe components achieve even greater efficiency and effectiveness, solidifying their role in advanced technological applications.
By understanding and utilising the properties and applications of ZnSe, industries can achieve remarkable advancements in technology and performance. For more detailed information on ZnSe, visit Crystran's Zinc Selenide page. For all inquiries please email our dedicated sales team at sales@crystran.co.uk.
Why Choose Crystran
Choosing Crystran as your optical components supplier ensures access to world-class expertise and state-of-the-art manufacturing facilities. Crystran specializes in fabricating high-quality IR and UV materials, including exotic crystals and innovative glasses, all processed under stringent quality controls. With ISO9001:2015 and ISO14001:2015 certifications, Crystran guarantees exceptional quality and environmental responsibility. Their technical sales team offers unparalleled support, ensuring quick, reliable service, whether you need a single optic or a high-volume production run. Crystran’s global reach and competitive pricing make them an ideal choice for optical solutions.
To learn more about our custom silicon optics, visit our website at crystran.com or contact our dedicated sales team at sales@crystran.co.uk for a quotation.