Broad Spectral Range
Useful transmission from approximately 0.6 to 20 µm, depending on grade, thickness, and coating.
Infrared Optical Material
Zinc Selenide (ZnSe)
Broadband Visible-to-Infrared Transmission for Laser and Imaging Systems.
A yellow transparent polycrystalline material widely used for CO₂ laser optics, thermal imaging, spectroscopy, and broadband infrared windows.
Why Zinc Selenide
A Versatile Broadband Material for Laser and Infrared Optics
Zinc selenide combines visible transparency, broad infrared transmission, low absorption at CO₂ laser wavelengths, and strong coating compatibility.
CO₂ Laser Performance
Low absorption near 10.6 µm makes ZnSe a standard material for high-power CO₂ laser windows and lenses.
Visible Alignment
Its yellow transparent appearance allows visible alignment in systems that also operate in the infrared.
Excellent Coating Platform
Supports broadband AR, laser-line, beamsplitter, filter, and protective coating designs.
Engineering Properties
Optical, Mechanical, and Thermal Characteristics
Representative values for optical-grade Zinc Selenide (ZnSe). Final values vary by material grade, wavelength, temperature, thickness, supplier specification, and test method.
Physical & Mechanical Properties
| Chemical Formula | ZnSe |
|---|---|
| Crystal Structure | Cubic zinc blende, typically polycrystalline |
| Density | Approximately 5.27 g/cm³ |
| Knoop Hardness | Approximately 120 |
| Young’s Modulus | Approximately 67 GPa |
| Poisson’s Ratio | Approximately 0.28 |
| Thermal Expansion | Approximately 7.1 × 10⁻⁶/K |
| Melting Point | Approximately 1525°C, material dependent |
Optical Properties
| Transmission Range | Approximately 0.6–20 µm, grade and thickness dependent |
|---|---|
| Refractive Index | Approximately 2.40 at 10.6 µm |
| Visible Appearance | Yellow to amber and transparent |
| Absorption at 10.6 µm | Low for laser-grade material |
| Dispersion | Moderate across visible and infrared bands |
| Coating Compatibility | VIS/NIR/MWIR/LWIR AR, laser-line, beamsplitter, and filter coatings |
| Available Grades | Optical, laser, low-absorption, and multispectral grades |
Optical Transmission
Broadband Transmission from Visible Light into the Infrared
ZnSe is valued for broadband systems and CO₂ laser optics because it transmits visible alignment light and important infrared wavelengths.
Representative only. Final transmission depends on grade, thickness, surface finish, absorption bands, and coating.
Material Comparison
When Zinc Selenide Is the Best Fit
| Property | Germanium | ZnSe | ZnS | Zinc Selenide (ZnSe) |
|---|---|---|---|---|
| Visible Transparency | No | No | Some grades | Excellent |
| CO₂ Laser Use | Specialized | Limited | Possible | Excellent |
| Spectral Range | Very Broad IR | NIR/MWIR | Broad IR | Broad VIS–IR |
| Mechanical Durability | Good | Very Good | Good | Moderate |
| Broadband Windows | Good | Limited | Very Good | Excellent |
Manufacturing Capabilities
From ZnSe Blank to Finished Laser or Infrared Optical Component
COE Sapphire supports prototype, low-volume, and repeat production of precision ZnSe windows, lenses, output couplers, beamsplitters, and custom infrared components.
Precision Machining
Controlled cutting, edging, beveling, coring, and custom geometry fabrication for zinc selenide.
Optical Polishing
Precision flat, spherical, aspheric, and custom polishing with process control for surface quality and edge integrity.
Optical Coating
MWIR and LWIR anti-reflection, protective, filter, and diamond-like carbon coatings.
Quality Assurance
Dimensional inspection, interferometry, surface inspection, transmission verification, and documentation.
Design Guide
Specify the Right Zinc Selenide Optical Component
Provide optical grade, operating wavelength, dimensions, tolerances, surface quality, flatness or power, wedge or parallelism, clear aperture, edge treatment, coating, quantity, and environmental requirements.
Discuss Your SpecificationMaterial GradeOptical, laser, low-absorption, or multispectral grade
Surface QualityCommercial through precision optical grades
Flatness / PowerApplication-specific interferometric control
Wedge / ParallelismPrecision parallel, wedged, or custom geometry
Edge TreatmentProtective bevel or chamfer recommended for fragile edges
CoatingsUV, VIS, NIR, MWIR, beamsplitter, and custom coatings
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Frequently Asked Questions
Zinc Selenide (ZnSe) Optical Material FAQs
What wavelength range does zinc selenide transmit?
ZnSe typically transmits from about 0.6 to 20 µm, depending on material grade, thickness, surface finish, and coating.
Why is ZnSe commonly used for CO₂ laser optics?
Laser-grade ZnSe offers low absorption near 10.6 µm and can be fabricated into windows, lenses, output couplers, and other high-power laser components.
Is ZnSe visible to the eye?
Yes. Zinc selenide is usually yellow to amber and visibly transparent, which can simplify optical alignment.
Is ZnSe mechanically strong?
ZnSe is softer than germanium, silicon, and many oxide materials, so edge protection, careful handling, and appropriate mounting are important.
What coatings are available for ZnSe?
Common options include broadband infrared AR, dual-band AR, laser-line AR, beamsplitter, filter, and protective coatings.
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