Zinc sulfide (ZnS) optical window

K9 optical window
  • CVD Zinc sulfide (ZnS) is divided into two materials, one is a white multispectral material and the other is a yellow primary material. It is a chemically inert material with the characteristics of high purity, insoluble in water, moderate density and easy processing. Due to the wide transmission band (500-10000nm) of zinc sulfide (ZnS), it is widely used in the manufacture of infrared windows, fairings and infrared optical elements.

  • Like zinc selenide (ZnSe), zinc sulfide (ZnS) is also a material with good refractive index uniformity and consistency. It has good image transmission performance in the 8000nm-12000nm band. The material also has high transmittance in the mid-infrared band, but as the wavelength becomes shorter, the absorption and scattering increase.
  • Compared with zinc selenide (ZnSe), zinc sulfide has a low price, high hardness, and twice the fracture strength of zinc selenide, and has strong resistance to harsh environments.
Technical parameters
Items Parameters
Material Zinc sulfide (ZnS)
Processable shapes circular, rectangular, polygonal and other shapes
Size range 3mm-500mm ± 0.1mm
Thickness 0.05-50mm
Center deviation 3′(we can process to 30 ″with high precision)
Parallelism less than 20″
Surface accuracy Reflective PV better than 1/4λ, transmissive PV better than 1/10λ
Surface quality 10-5 20-10 40-20 60-40
Surface roughness less than 5nm
Effective caliber ≥90%
Coating According to the custom requirements
spectral curve (coating before)
Zns optical window
ZnS flat lens

Physical and chemical properties of zinc sulfide ZnS

CVD Zinc Sulfide ZnS Multi-spectrum CVD Zinc Sulfide ZnS
Density (g/cm3) 4.09 4.09
Melting point (℃) 1827 1827
Resistivity Ω.CM ~10^12 ~10^13
Chemical purity (%) 99.9996 99.9996
Thermal expansion coefficient (1/℃) 6.6*10^-6@273K 6.3*10^-6@273K
7.3*10^-6@373K 7.0*10^-6@373K
Thermal conductivity (J/k.m.s) 16.7@298K 27.2@298K
Heat capacity (J/g.k) 0.469@298K 0.515@298K
Knoop hardness (kg/mm2) 200-235 160
Bending strength (MPa) 103
Young's modulus(GPa) 74.5 74.5
Poisson's ratio 0.29 0.28

Optical properties of zinc sulfide ZnS

CVD Zinc Sulfide ZnS Multi-spectrum CVD Zinc Sulfide ZnS
Transmission wavelength range 1000nm-14000nm 370nm-14000nm
Refractive index inhomogeneity (ΔN/N) <7.3*10^-4@10600nm <0.2*10^-4@632.8nm
Absorption coefficient (1/cm) 0.2@10600nm 0.2@10600nm
Thermo-optic coefficient, dn/dT (1/K, 298-358K) 4.6*10^-5@1150nm 5.43*10^-5@632.8nm
4.3*10^-5@3390nm 4.21*10^-5@1150nm
4.1*10^-5@10600nm 3.87*10^-5@3390nm

Changes in refractive index of zinc sulfide material with wavelength (CVD zinc sulfide 20°C)

Wavelength (nm) Refractive index (n) Wavelength (nm) Refractive index (n)
620 2.355 9800 2.203
1000 2.292 10600 2.192
3800 2.253 11400 2.180
5000 2.246 12200 2.167
7000 2.232 13800 2.132
9000 2.212 14200 2.126

Variation of refractive index with wavelength (Multi-spectrum CVD zinc sulfide 20°C)

Wavelength (nm) Refractive index (n) Wavelength (nm) Refractive index (n)
400 2.545 8000 2.223
1010 2.292 9000 2.213
2060 2.264 10000 2.201
3500 2.255 11250 2.183
4500 2.250 12000 2.171
5000 2.247 13000 2.153

Window Materials Quick Guide

Wavelength range Window material
180 nm - 8.0 μm Calcium Fluoride CaF2
185 nm - 2.1 μm UV Fused Silica
200 nm - 5.0 μm Sapphire
200 nm - 6.0 μm Magnesium fluoride MgF2
600 nm - 16 µm Zinc Selenide ZnSe
1.9 - 16 μm Germanium single crystal Ge
2 - 5 μm Barium fluoride BaF2

In addition, We can customize the optical window according to customer requirements or drawings.

For details, please consult:

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