Zinc Selenide (ZnSe) is a polycrystalline infrared material with excellent transmission from the visible through the far infrared. It is the standard material for CO₂ laser optics and is widely used in thermal imaging and IR spectroscopy systems.
CO₂ laser windows and lenses
Thermal imaging systems
FTIR spectroscopy
Medical laser systems
IR optical sensors
| Property | Value |
|---|---|
| Coefficient of Thermal Expansion (CTE) | 7.1 × 10⁻⁶ /K |
| Thermal Conductivity | 18 W/m·K |
| dn/dT (Thermo-optic Coefficient) | 61 × 10⁻⁶ /K at 10.6 μm |
| Maximum Operating Temperature | ~150°C |
ZnSe has moderate thermal properties. The relatively high dn/dT requires thermal consideration in high-power CO₂ laser applications.
Standard coating types available for this material. Custom coating designs available on request.
Soft material, easy to machine and diamond turn. One of the easiest IR materials to fabricate.
Good polishability with standard methods. Achieves excellent surface finish for CO₂ laser optics.
Slight moisture absorption over time. Handle with clean gloves to avoid surface contamination.
High cost due to expensive raw material. Premium pricing for large-aperture and high-purity grades.
No single optical material is perfect for every application. Here are situations where Zinc Selenide (ZnSe) may not be the best fit, and what to consider instead.
→ Consider: Zinc Sulfide (ZnS)
ZnSe begins to absorb more strongly at elevated temperatures. For sustained high-temperature IR operation, ZnS is more thermally stable.
→ Consider: Zinc Sulfide or hard-coated alternatives
ZnSe is soft (Mohs ~2.5) and prone to scratching. For field-deployed optics exposed to dust, sand, or cleaning, ZnS or hard-coated ZnSe offer better survival.
→ Consider: Silicon or Sapphire
ZnSe's advantage is broadband IR transmission, but if you only need SWIR, silicon is significantly cheaper with better mechanical properties.
→ Consider: Silicon
ZnSe has a density of 5.27 g/cm³. For weight-critical applications, silicon at 2.33 g/cm³ is less than half the weight.
Browse our catalog of precision optical components available in Zinc Selenide (ZnSe)
Consider ZnS if mechanical durability is a higher priority. ZnSe offers excellent broadband IR transmission but is softer and more susceptible to damage. Avoid in high-power laser applications without proper coating.
Send us your specifications. Our engineering team will review and respond with material and coating recommendations within 24 hours.
Request a Quote