ZnS window

ZnS materials have two grades and can be use in imaging systems. Regular grade material is grown by the chemical vapor deposition process. This material is often used in the 3um to 5 um and 8um to 12 um region. It has reasonable hardness and is moderately priced.

Multi Spectral grade ZnS
(CLEARTRAN ZnS) is treated after growth to eliminate microscopic voids and defects which occur in the regular grade, thus extending the usefulness of this material to include the visible region.

Compared with zinc selenium (ZnSe), zinc sulfide is lower priced and harder, more resistant to inclement weather, with fracture strength two times that of zinc selenium, thus making it an ideal material for production of missile radome and infrared winder for military aircrafts.


Physical and chemical properties

 

CVD zinc sulfide

Multi Spectral CVD zinc sulfide

Density (g.cm-3@298k)

4.09

4.09

Specific resistance (Ω.cm)

~1012

~1013

Melting point ()

1827

 

Chemical purity (%)

99.9996

99.9996

Thermal expansion coefficient (1/k)

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

Thermal 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

Poissons ratio

0.29

0.28

Optical properties

 

CVD zinc sulfide

Multi Spectral CV zinc sulfide

Transmission wavelength range

1.0μm-14μm

0.37μm-14μm

Refractivity unevenness, n/n

<3×[email protected]μm

<0.2×[email protected]μm

Absorption coefficient (1/cm)

[email protected]μm

[email protected]μm

Thermal optical coefficient, dn/dt (1/k,

4.6×[email protected]μm

5.43×[email protected]μm

298-358k)

   
 

4.3×[email protected]μm

4.21×[email protected]μm

 

4.1×[email protected]μm

3.87×[email protected]μm

 

Change of refractivity n as a function of wavelength

CVD ZnS (20):

Wavelength (μm)

Refractivity (n)

Wavelength (μm)

Refractivity (n)

0.62

2.355

9.80

2.203

1.00

2.292

10.60

2.192

3.80

2.253

11.40

2.180

5.00

2.246

12.20

2.167

7.00

2.232

13.80

2.132

9.00

2.212

14.20

2.126

Multi Spectral CVD zinc sulfide (CLEARTRAN ZnS)(20)

Wavelength (μm)

Refractivity (n)

Wavelength (μm)

Refractivity (n)

0.40

2.545

8.00

2.223

1.01

2.292

9.00

2.213

2.06

2.264

10.00

2.201

3.50

2.255

11.25

2.183

4.50

2.250

12.00

2.171

5.00

2.247

13.00

2.153

 

Specifications

Material

CVD ZnS

Dimension Tolerance

+0.0/-0.1mm

Thickness Tolerance

±0.2mm

Clear Aperture

>90%

Parallelism

<1arc minutes

Surface Quality

60/40 or better

Flatness

<λ /2@633nm or better

Chamfer

Protected <0.5mmx45deg

Coating

None, per your request


 



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