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Zinc Sulfide (ZnS) Windows

  • Maximum diameter 250mm
  • CVD Grown Zinc Fluoride and Multispectral Zinc Sulfide (Cleartran)
  • Transmission range 0.4-14.0μm (Multispectral Zinc Sulfide)
  • Excellent mechanical strength and chemical inertness for harsh environments (harder than ZnSe Windows)
  • Coating Options: AR/AR coating
Curves of ZnS Windows.pdf All.pdf Inquire Us  


Materials CVD ZnS Crystals, FLIR Grade or CleartranDiameter Range ~ 250mm
Aperture >90% Dimension Tolerance +0.0/-0.2mm
Thickness Tolerance +/-0.1mm Surface Quality 60/40 S/D
Parallelism 1 arc minute Chamfer 0.3-0.5mmx45degree
Coating AR/AR coating@7-14μm


Physical and Optical Properties:

Transmission Range 0.37 to 13.5 μm Refractive Index 2.20084 at 10 μm
Reflection Loss 24.7% at 10 μm (2 surfaces) Absorption Coefficient 0.0006 cm-1 at 3.8 μm
Reststrahlen Peak 30.5 μm dn/dT +38.7 x 10-6  /°C at 3.39 μm
dn/dμ = 0 n/a Density 4.09 g/cc
Melting Point 1827°C (See notes below) Thermal Conductivity 27.2 W m-1 K-1 at 298K
Thermal Expansion 6.5 x 10-6 /°C at 273K Hardness Knoop 160 with 50g indenter
Specific Heat Capacity 515 J Kg-1 K-1 Dielectric Constant 88
Youngs Modulus (E) 74.5 GPa Shear Modulus (G) n/a
Bulk Modulus (K) n/a Elastic Coefficients Not Avalailable
Apparent Elastic Limit 68.9 MPa (10,000 psi) Poisson Ratio 0.28
Solubility 65 x 10-6 g/100g water Molecular Weight 97.43
Class/Structure HIP poly-crystalline cubic, ZnS, F42m

Optical grade Zinc Sulfide is a synthetic component made from Chemical Vapour Deposition (CVD). However, normal CVD ZnS is opaque in the visible spectrum, this material is often used in the LWIR (7 to 14 micro) region of thermal imaging and sold under the name Forward Looking Infrared (FLIR) grade ZnS. There is also Multispectral ZnS (or Cleartran), which goes under a further post-deposition hot isostatic press process after the CVD fabrication, increasing the transmission rate to a single-crystal like altitude across the Visible to IR range (0.4-14.0μm). The hot press process eliminates the water composition of ZnS, therefore this material is also known as water-clear ZnS.

Hangzhou Shalom EO offers windows made from FLIR grade ZnS, and Multispectral (Cleartran) Zinc Sulfide. Various custom shapes and anti-flection coatings on two surfaces are available. The multispectral ZnS windows are exceptional for applications through out UV, VIS, and IR region (e.g. visible camera, mid-and long-wave detectors, and laser rangefinders). In comparison FLIR grade ZnS is harder, although both FLIR grade and Multispectral (Cleartran) Zinc Sulfide has higher mechanical strength than ZnSe and could adapt to applications under extreme conditions (e.g. exterior IR windows on aircraft frames).

1. Transmission of 3mm Thickness ZnS Cleartran Windows at 550-850nm 

Transmission of ZnS Cleartran windows

2. Transmission of 3mm Thickness ZnS Cleartran Windows at 1000-1100nm

Transmission of ZnS Cleartran windows

3. Transmission of 3mm Thickness ZnS Windows at 8-12 micro

Transmission of ZnS Cleartran windows