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CVD - ZnSe
ZnSe is used as a material for production of optical elements (windows,
lenses, prisms) for IR range including the passive laser optics elements.
CVD - ZnSe is extremely uniform in structure; it has superior optical
transmission with extremely low bulk losses from scatter and absorption.
CVD - ZnSe is the first choice for high power laser windows and multispectral
application with useful transmitting range of
0.5 - 19 mm. It offers excellent imaging characteristics, high resistance to thermal shock, and is stable in virtually all operating environments. This material is soft and non-hygroscopic.
Physical properties of ZnSe
|
Density @ 300 K, g/cm3 |
5.27 |
| Melting point, K |
1798 |
| Thermal conductivity @ 298 K, J/(K x m x c) |
18.0 |
| Thermal expansion,
1/K |
@ 273 K |
7.1 x 10-6 |
| @ 373 K |
7.8 x 10-6 |
|
@ 473 K |
8.3 x 10-6 |
|
Heat capacity @ 298 K, J/(g x K) |
0.339 |
| Hardness |
Knoop, with 50 g indenter, kg/mm2 |
120 |
| Vickers, with 1 kg indenter, kg/mm2 |
112 |
|
Youngs modulus (E), Gpa |
67.2 |
|
Bulk modulus (K), Gpa |
40 |
|
Apparent elastic limit, Mpa |
55.1 |
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Fracture toughness MN m-1.5, Vickers, 100 g |
0.5 |
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Poisson's ratio |
0.28 |
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Solubility |
Insoluble in water |
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Resistivity, Ohm x cm |
1012 |
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Optical properties
Thermo-optic coefficient, (dn/dT)
@ 10.6 mm @ 298-358 K, 1/K |
6.1 x 10 -5 |
| Restrahlen peak, mm |
45.7 |
| Reflection loss @ 10.6 mm (2 surfaces), % |
29.1 |
Reflection inhomogeneity (dn/n)
@ 0.633 mm, less than |
3 x 10 -5 |
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ZnSe refractive index vs wavelength
| λ, μm |
n |
λ, μm |
n |
λ, μm |
n |
| 0.54 |
2.6754 |
3.00 |
2.4376 |
10.60 |
2.4028 |
| 0.58 |
2.6312 |
3.40 |
2.4356 |
11.40 |
2.3974 |
| 0.62 |
2.5994 |
3.80 |
2.4339 |
11.80 |
2.3945 |
| 0.66 |
2.5755 |
4.20 |
2.4324 |
12.20 |
2.3915 |
| 0.70 |
2.5568 |
4.60 |
2.4309 |
12.60 |
2.3883 |
| 0.74 |
2.5418 |
5.00 |
2.4295 |
13.00 |
2.3850 |
| 0.78 |
2.5295 |
5.40 |
2.4281 |
13.40 |
2.3816 |
| 0.82 |
2.5193 |
5.80 |
2.4266 |
13.80 |
2.3781 |
| 0.86 |
2.5107 |
6.20 |
2.4251 |
14.20 |
2.3744 |
| 0.90 |
2.5034 |
6.60 |
2.4235 |
14.60 |
2.3705 |
| 0.94 |
2.4971 |
7.00 |
2.4218 |
15.00 |
2.3665 |
| 0.98 |
2.4916 |
7.40 |
2.4201 |
15.40 |
2.3623 |
1.00 |
2.4892 |
7.80 |
2.4183 |
15.80 |
2.3579 |
1.40 |
2.4609 |
8.20 |
2.4163 |
16.20 |
2.3534 |
1.50 |
2.4560 |
8.60 |
2.4143 |
16.60 |
2.3487 |
1.80 |
2.4496 |
9.00 |
2.4122 |
17.00 |
2.3438 |
2.00 |
2.4460 |
9.40 |
2.4100 |
17.40 |
2.3387 |
2.20 |
2.4437 |
9.80 |
2.4077 |
17.80 |
2.3333 |
2.60 |
2.4401 |
10.20 |
2.4053 |
18.20 |
2.3278 |
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Depending on application we use two grades of CVD - ZnSe with different optical properties. There is no difference in transmission at 8 mm and above (see Fig.1).
Fig. 1 Transmission spectrum of CVD - ZnSe window thickness of 10 mm.
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G 1
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G 2
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Absorption index
@ 10.6 mm, less than, 1/cm |
(5 - 8) x 10 - 4 |
1 x 10 -3 |
| Damage threshold, not less than, kW/cm2 |
2 - 3 |
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CVD - ZnSe blanks are available in diameters 2 - 200 mm with thickness to 15 - 20 mm.
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