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Material - Zinc Selenide ZnSe CVD
ZnSe is used for optical windows, lenses, mirrors, prisms and optical blanks, plates, disks, sheets, slabs particularly for infrared applications
Zinc Selenide (ZnSe) - transparent in wide spectral range from yellow (visible) to far IR. ZnSe material is a chemically inert, non-hygroscopic and highly pure product that is very effective in many optical applications due to its extremely low bulk losses, high resistance to thermal shock and stability in virtually all environments, easily machined. To obtain superior transmittance, ZnSe crystals are grown by Chemical Vapor Deposition process (CVD). Zinc Selenide CVD is polycrystalline material, demonstrates superior CO2 laser transmittance and is employed in the transmission optical components used in CO2 laser processing.
ZnSe (Zinc Selenide) Chemical Vapor Deposition (CVD) material is produced by synthesis from zinc vapour and H2Se gas, forming as sheets on graphite susceptors (ZnSe-CVD processes). Chemical purity of CVD-ZnSe 99.999%. It has à polycrystalline structure; the grain size of Zinc Selenide CVD material is controlled to produce maximum strength.
The transmission range of Zinc Selenide ZnSe-CVD is (0.5 – 20) microns. ZnSe CVD used for high power CO2 laser optics at 10.6 microns, for protective optics windows or optical elements in FLIR (forward looking infrared) thermal imaging equipment, optics for medical and industrial applications (optical plane parallel windows (plates, disks, sheets, slabs, blanks), wedged windows, Brewster windows, optical meniscus, spherical and cylindrical lenses, prisms, resonator mirrors of CO2 laser).
Single crystal ZnSe Zinc Selenide is available, but is not common, it has lower bulk losses and thus more effective for CO2 optics.
Crystaltechno Ltd.
- grows Zinc Selenide (ZnSe) CVD ingots with size up to 270 mm x 500 mm, thickness up to 20mm, transparent during the spectral range (0.5 -20) microns.
- manufactures from Zinc Selenide ZnSe CVD the following optics
blanks, windows, protective windows, wedges, cylindrical and spherical lenses, meniscus, right angle prisms, ATR prisms, CO2 optics, resonator mirrors for CO2 laser at 10.6 microns, Brewster windows, domes, spherical microlenses, balls and hemisphere, ZnSe witness samples. These products are particularly for infrared applications including CO2 laser optics.
- offers Evaporation Grade Zinc Selenide ZnSe-CVD (size less than or equal to 6 mm, purity: 99.999%)
ZNSE (ZINC SELENIDE) BASE PROPERTIES
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PARAMETER |
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VALUE |
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| PHYSICAL PROPERTIES of Zinc Selenide (ZnSe) |
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Density |
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5.27 g/cm3 |
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Melting Point |
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1525°C (dissociates about 700°C) |
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Thermal Conductivity |
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18 W/(m K) at 298K |
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Thermal Expansion |
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7.1 x 10-6/°C at 273K |
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Hardness |
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Knoop 120 with 50g indenter |
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Specific Heat Capacity |
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339 J/(kg K) |
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Young's Modulus (E) |
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67.2 GPa |
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Bulk Modulus (K) |
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40 GPa |
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Apparent Elastic Limit |
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55.1 MPa (8,000psi) |
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Poisson Ratio |
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0.28 |
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Resistivity |
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~1012 (Ohm x cm) |
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| CHEMICAL PROPERTIES of Zinc Selenide ZnSe CVD |
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Solubility |
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0.001 g/100g water |
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Molecular Weight |
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144.33 |
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Crystal Structure |
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polycrystalline
ZnSe (CVD) Laser grade, grain size (50-70) microns
ZnSe (CVD) IR optical grade, grain size (20-100) microns
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| OPTICAL PROPERTIES of ZnSe Zinc Selenide CVD |
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Transmission Range |
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0.6 - 21.0 microns |
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Refractive Index |
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2.4028 at 10 microns |
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Reflection Loss |
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31.11% at 10.6 µm (2 surfaces) |
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dn/dT |
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+61 x 10-6/°C at 10.6µm at 298K |
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dN/dµ = 0 |
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5.5µm |
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Index of Absorption |
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ZnSe-CVD Laser grade 0.0005 (1/cm) at 10.6 microns
ZnSe-CVD IR optical grade 0.003 (1/cm) at 10.6 microns
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ZNSE (ZINC SELENIDE) REFRACTIVE INDEX
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Wavelength, µm |
2.75 |
5.00 |
7.50 |
9.50 |
11.0 |
12.5 |
13.5 |
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Refractive Index |
2.44 |
2.43 |
2.42 |
2.41 |
2.40 |
2.39 |
2.38 |
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Wavelength, µm |
15.0 |
16.0 |
16.9 |
17.8 |
18.6 |
19.3 |
20.0 |
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Refractive Index |
2.37 |
2.36 |
2.35 |
2.34 |
2.33 |
2.32 |
2.31 |
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Because of high refractive index (n=2.4 at 10.6 microns), Fresnel losses of Zinc Selenide polished surface are equal 17% (at one side), thus the transmission of ZnSe polished window equals 68.9% at 10.6 micron. We offer two sides antireflection (AR/AR) coating both for one wavelength (10.6 microns or another) and for the spectral range (3 – 12) microns. Transmission of AR/AR coated ZnSe Zinc Selenide CVD window - up to 99%.
We produce two kinds of CVD grown ZnSe (Zinc Selenide) material, which differ in spectral transmittance and grain size, namely
- CVD-ZnSe laser grade, grain size (50-70) microns, index of absorption 0.0005 (1/cm) at 10.6 microns, optical component dimensions (3 – 100) mm, thickness 20mm, used in high power CO2 laser optics, in medical applications.
- CVD-ZnSe IR optical grade, grain size (20-100) microns, index of absorption 0.003 (1/cm) at 10.6 microns, optical component dimensions (3 - 300) mm, thickness 20mm, used in protective windows and thermal imaging equipment, in industrial applications.
ZnSe laser grade material price is higher than IR optical grade price.
You can see both spectral transmittance of laser grade and IR optical grade uncoated polished ZnSe windows (thickness 2 mm) below.
Spectral transmittance (T) of ZnSe laser grade uncoated polished window (thick. 2mm), range (2.5–20) microns. For visible range T greater than or equal to 62% at 633 nm.
Spectral transmittance (T) of Zinc Selenide IR optical grade uncoated polished window (thick. 2mm), range (2.5–20) microns.
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