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ZnSe Optics

ZnSe (Zinc Selenide) is a kind of good material for optical components such as lenses, windows, prisms, output couplers, and beam expanders because of its typical low absorptivity at the vision and infrared wavelengths. For high-power laser applications, it is critical that the material bulk absorption and internal defects should be carefully controlled, that super polishing technology is employed, and the highest quality optical thin-film coatings are used. The material absorption is verified by CO2 laser vacuum calorimetry.

ZnSe crystals are grown by Chemical Vapor Deposition (CVD) method to obtain high transmittance. CVD ZnSe mostly is polycrystalline material but single crystal ZnSe (zinc selenide) is also available just is not that common, it has lower bulk losses so more effective for CO2 optics. ZnSe is non-hygroscopic and chemically stable unless treated with strong acids. It is safe to use in most industrial field and laboratory environments. Honour Optics is the professional CVD ZnSe optics and custom Infrared and Broadband ZnSe optics manufacturer, welcome to consult wholesale laser grade ZnSe optics.

ZnSe (Zinc Selenide) - has great transmittance through the band 0.5-22μm. high-quality Chinese ZnSe optics 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.

ZnSe (Zinc Selenide) material is produced by synthesis from zinc vapor and H2Se gas, forming as sheets on graphite susceptors. Chemical purity of CVD-ZnSe could achieve nearly 99.999%. It has a polycrystalline structure; the grain size of Zinc Selenide CVD material is controlled to produce maximum strength and machinability.

ZnSe (Zinc Selenide) is a kind of relatively soft material that scratches and digs can easily remain on the surfaces during the polishing process, it is not recommended for use within harsh environments, Honour Optics’ advanced manufacturing experience for high-quality Chinese ZnSe optics ensure superior surface quality. For cosmetic sensitive systems, our best effort can reach 10/5 S/D even better. welcome to consult purchasing large size ZnSe optics.

ZnSe high resistance to thermal shock makes it the prime material for high power CO2 laser systems.
ZnSe is only 2/3 the hardness of ZnS multi-special grade, but the harder anti-reflectance coatings serve to protect ZnSe.
ZnSe’s cost is about the same as ZnS multispectral grade.
Generally more expensive than Ge.
ZnSe is diamond turnable.

Products manufactured: Lenses, Aspheric Lenses, Binary (diffractive) Lenses, Windows, Optical Beamsplitters and Optical Filters, Prism. welcome to consult purchasing large size ZnSe optics.

Surface finish: Typical specifications for surface quality in the infrared are 40-20 or 60-40 scratch-dig in the 0.8 to the 7μm spectral region and 60-40 scratch-dig for the 7 to 16μm area, depending upon system performance requirements. Diamond Turned surface finishes of 150 Angstroms RMS or better are typical.

Surface figure: In the infrared, typically required surface figures range from 1/2 wave to 2 waves @0.6328 μm depending on the system performance requirements.

AR coating options: Typically available coatings for ZnSe include BBAR for 0.8 to 2.5μm, 3 to 5μm, 1 to 5μm, 8 to 12μm, and the 3 to 12μm spectral regions and single wavelength coating AR at 10.6μm. Many other specialized wavelength bands are possible within the 0.6 to the 16μm range.

Tab. 1.Main Properties

Transmission Range 0.6 to 21.0μm
Refractive Index 2.4028 at 10μm
Reflection Loss 29.1% at 10.6μm (2 surfaces)
Absorption Coefficient 0.0005cm-1 at 10.6μm
Restrahlen Peak 45.7microns
dn/dT +61 x 10-6/°C at 10.6μm at 298K
dn/dμ = 0 5.5μm
Density 5.27g/cm3
Melting Point 1525°C (dissociates about 700°C)
Thermal Conductivity 18 W/(m K) at 298K
Thermal Expansion 7.1 x 10-6/ °C at 273K
Hardness Knoop 120 with the 50g indenter
Specific Heat Capacity 339 J · kg-1 · K-1
Bulk Modulus (K) 40 GPa
Young's Modulus (E) 67.2 GPa
Apparent Elastic Limit 55.1 MPa (8,000psi)
Poisson Ratio 0.28

Tab. 2.Refractive index of ZnSe crystal

µm No µm No µm No
0.54 2.6754 0.58 2.6312 0.62 2.5994
0.66 2.5755 0.7 2.5568 0.74 2.5418
0.78 2.5295 0.82 2.5193 0.86 2.5107
0.90 2.5034 0.94 2.4971 0.98 2.4916
1.0 2.4892 1.4 2.4609 1.8 2.4496
2.2 2.4437 2.6 2.4401 3.0 2.4376
3.4 2.4356 3.8 2.4339 4.2 2.4324
4.6 2.4309 5.0 2.4295 5.4 2.4281
5.8 2.4266 6.2 2.4251 6.6 2.4235
7.0 2.4218 7.4 2.4201 7.8 2.4183
8.2 2.4163 8.6 2.4143 9.0 2.4122
9.4 2.4100 9.8 2.4077 10.2 2.4053
10.6 2.4028 11.0 2.4001 11.4 2.3974
11.8 2.3945 12.2 2.3915 12.6 2.3883
13.0 2.3850 13.4 2.3816 13.8 2.3781
14.2 2.3744 14.6 2.3705 15.0 2.3665
15.4 2.3623 15.8 2.3579 16.2 2.3534
16.6 2.3487 17.0 2.3438 17.4 2.3387
17.8 2.3333 18.2 2.3278

Tab. 3.Common specification of ZnSe optics

Specification Typical Level High precision
Sizes 2mm-200mm 2mm-200mm
Diameter tolerance +/-0.1mm +/-0.05mm
Thickness tolerance +/-0.1mm +/-0.05mm
Surface quality, scr/dig 60/40 10/5
Surface flatness(lambda) L/2 L/10
Parallelism 3 arc min 30 arc sec
Clear Aperture 80% 90%
Chamfer 0.25mm at 45 deg 0.15mm at 45 deg
Coating As requested As requested

Transmission Spectrum-Standard 8-12um AR coating

CVD ZnSe optics transmission spectrum standard 8 12um AR coating

Transmission Spectrum-2

ZnSe optics transmission spectrum

CVD ZnSe is widely used for industrial, military and medical applications. CVD ZnSe is also the first choice of optical components for high power CO2 lasers due to its low bulk absorption at 10.6 microns. Honour Optics is the professional CVD ZnSe optics and custom Infrared and Broadband ZnSe optics manufacturer, welcome to consult wholesale laser grade ZnSe optics.

Honour Optics normally offers two kinds coatings for ZnSe optics, one is AR coatings for one wavelength such as 10.6 microns for CO2 lasers or another single wavelength; another is BBAR coatings for the spectral range about 3 - 12 microns. Transmission of AR coated CVD Zinc Selenide window could achieve 99% at 10.6 microns. Honour Optics also offers other coatings like HR and dichroic, please contact us for your need.

Honour Optics has many years experiences of manufacturing custom-made ZnSe optics for a wide variety of applications, including, but not limited to:
• Amplifier Slabs, discs, rods, wedged windows, ATR prisms, spherical, cylindrical, domes, fairings etc.
• Debris Shields
• Laser fusion optics
• Reference Surfaces
• Defense/Aerospace
• Medical/Life Sciences
• Industrial OEM

Honour Optics also offers prism grade ZnSe. Prism grade ZnSe with minimal refractive index variations within the material and commonly used in thermal imaging systems.

Honour Optics manufactures large-size ZnSe optics such as plates, lenses, prisms, and domes. At the moment we produce ZnSe domes with a diameter up to 200 mm, wall thickness up to 10 mm.

Honour Optics is the professional manufacturer of ZnSe (Zinc Selenide) with ROHS environmental protection requirements. Honour Optics could provide:
The round, rectangular, plane parallel and wedged windows;
Spherical, cylindrical and meniscus lenses;
AR/AR coated CO2 laser optics;
Right angle, Dove, ATR prisms