OPTICS CRYSTALS LASERS
   
 

Material — polycrystalline Zinc Selenide - CVD ZnSe

ZnSe is used for optical windows, domes, 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 high transmittance ZnSe crystals are grown by Chemical Vapor Deposition process (CVD). CVD Zinc Selenide is polycrystalline material which is used in the optical components of CO2 laser systems and IR optical devices.

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 a polycrystalline structure; the grain size of Zinc Selenide CVD material is controlled to produce maximum strength and machinability.

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), domes, 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 (CVD ZnSe) ingots with size up to (270 x 500) mm, thickness up to 35 mm, transparent in the spectral range (0.5 - 20) microns.
  • manufactures from Zinc Selenide (CVD-ZnSe) the following optics: blanks, windows, protective windows, domes, wedges, cylindrical and spherical lenses, meniscus, right angle prisms, ATR prisms, CO2 optics, resonator mirrors for CO2 laser at 10.6 microns, Brewster windows, spherical microlenses (balls and hemisphere) and ZnSe witness samples. These products are used for infrared applications including CO2 laser optics.
  • offers Evaporation Grade Zinc Selenide (CVD-ZnSe), size less than or equal to 6 mm, purity: 99.999%.
Our company has a full cycle of CVD ZnSe optics manufacturing from simple chemicals to finished optics with coating and offers all the Zinc Selenide products within this line including semi-finished items. Along with Zinc Selenide growth material (sheets, SMTY) we offer ZnSe blanks cut according to customers size and inspection polished sheets. Our facility allows to produce the standard CO2 optics such as ZnSe windows, ZnSe plano-convex lenses and ZnSe meniscus.

At the same time we offer wide range of custom designs ZnSe optics with complex shape such as FLIR windows with profiled mounting grooves. We manufacture CVD-ZnSe hemisphere domes and CVD-ZnSe hyperhemisphere domes where ZnSe transmission is perfect for multichannel optical devices.

Our optical products have aroused great interest at the optical, laser exhibitions and trade fairs, especially, ZnSe optics due to good properties of our CVD Zinc Selenide material in visible and IR range of spectrum.

Many optical companies are interested in CVD-ZnSe SMTY (Sufficient Material To Yield) material, blanks, sheets and CVD ZnSe optical components too: Zinc Selenide domes, ZnSe protective windows, ZnSe prisms, ZnSe lenses and the antireflection coated Zinc Selenide optics, including large-sized optics - ZnSe plates and ZnSe domes. A new CVD ZnSe technology of dome-generated growth was developed on our CVD-Zinc Selenide growth facility. For the moment we produce ZnSe domes with diameter up to 300 mm, wall thickness up to 15 mm and domes height up to 1.3 R ( where R - domes curvature radius). The main application of ZnSe domes is common-aperture imaging systems working in the spectral range (0.63 - 14) microns.

Complex shape and profile of ZnSe optics are made using advantages of CVD technology which provides best ZnSe prices and quality.

Zinc Selenide blanks and sheets made by Crystaltechno Ltd have now the best price-quality ratio. Our ZnSe material is approved by European military organization for use in IR imaging systems.

Perhaps you will find required ZnSe optics at our stock, please see item Optical Crystals.

ZNSE (ZINC SELENIDE) BASE PROPERTIES

PARAMETER VALUE
PHYSICAL PROPERTIES of Zinc Selenide (ZnSe)  
  Density   5.27 g/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, with 50 g indenter, kg/mm2   120  
  Specific Heat Capacity   339 J/(kg K)  
  Young's Modulus (E)   67.2 GPa  
  Bulk Modulus (K)   40 GPa  
  Apparent Elastic Limit   55.1 MPa (8,000psi)  
  Poisson Ratio   0.28  
  Resistivity   ~1012 (Ohm x cm)  
CHEMICAL PROPERTIES of Zinc Selenide ZnSe CVD  
  Solubility   0.001 g/100g water  
  Molecular Weight   144.33  
  Crystal Structure   Cubic, “zincblende” structure, polycrystalline CVD ZnSe grain size (50-70) microns  
OPTICAL PROPERTIES of ZnSe Zinc Selenide CVD  
  Transmission Range   (0.5 - 20) microns  
  Refractive Index   2.4028 at 10 microns  
  Reflection Loss   29.1% at 10.6 µm (2 surfaces, with subsequent multiple internal beam reflections)  
  dn/dT   + 61 x 10 -6 / °C at 10.6 microns at 298K  
  dn/dµ = 0   5.5 µm  
  Index of Absorption   0.0005 (1/cm) at 10.6 microns, ZnSe-CVD Laser grade  

ZNSE (ZINC SELENIDE) REFRACTIVE INDEX

  Wavelength, µm 2.75 5.00 7.50 9.50 11.0 12.5 13.5  
  Refractive Index 2.44 2.43 2.42 2.41 2.40 2.39 2.38  
  Wavelength, µm 15.0 16.0 16.9 17.8 18.6 19.3 20.0  
  Refractive Index 2.37 2.36 2.35 2.34 2.33 2.32 2.31  


TRANSMISSION of UNCOATED and AR/AR COATED ZNSE OPTICS

Because of high refractive index (n = 2.4 at 10.6 microns), calculated Fresnel losses of Zinc Selenide polished surface are equal 17% (at one side), thus the transmission (T) of ZnSe polished window equals T = 68.9 % at 10.6 micron (without absorption). Note all calculations are done for wavelength of CO2 laser 10.6 microns leaving out of account the possible multiple internal beam reflections.

. If ZnSe window is a plane parallel plate and laser beam with good (plane wave) incidences perpendicularly to a ZnSe window surface (normal incidence), in this case we must take into account subsequent multiple internal beam reflections inside of ZnSe plate. So transmission (Tw) of a uncoated ZnSe window subject to multiple reflections (5 times) will be 1.03 times more, namely Tw = 70.9% (without absorption). Hence Reflection Loss in this case equals 29.1%. Even if one of mentioned above conditions is absent, transmission of Zinc Selenide window will equal T = 68.9 % at 10.6 micron (without absorption). As to another wavelength 13.5 microns refractive index n = 2.38, so T = 69.4% (without absorption) and Tw = 71.4% (without absorption). You can see spectrum transmission chart of ZnSe window below.

Spectral Transmittance (T) of CVD-ZnSe Uncoated Polished Windows: first - thickness 5mm for range (400 - 1100) nm and second - thickness 10mm for range (2.5 - 25) microns.


Usually consideration of internal multiple reflections inside of ZnSe detail is not necessary for a ZnSe lens and a ZnSe wedge, because the lens strongly changes a beam divergence, and wedge directs reflected beam out of main optical axis. Hence as a rule transmission of uncoated ZnSe wedge and ZnSe lens equals T = 68.9 % at 10.6 micron (without absorption). So we have considered a ZnSe optics transmission without taking into account radiation absorption and scattering inside Zinc Selenide material.

As to bulk absorption of ZnSe optics, it is necessary to consider and calculate value of absorbed power for high power CO2 lasers and CO2 laser machines, because ZnSe optics may be heated and distorted as result of high power radiation absorption.

Crystaltechno Ltd produces CVD grown ZnSe (Zinc Selenide) material with low absorption, namely index of absorption of Zinc Selenide material equals 0.0005 (1/cm) at 10.6 microns. For example we calculate the bulk transmission (Tb) of 1 cm thickness (ZnSe material) as Tb = exp (- 0.0005 x 1), Tb = 0.9995 or 99.95% at 10.6 microns. This value must be considered in calculation of real transmission for ZnSe optical components.

Crystaltechno Ltd offers 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 CVD Zinc Selenide window - up to 99% at 10.6 microns.

We produce optics from CVD grown ZnSe laser grade material with the following characteristics: grain size (50 - 70) microns, index of absorption 0.0005 (1/cm) at 10.6 microns. Zinc Selenide optical components dimensions - (3 - 100) mm, thickness 20mm. ZnSe optics is used in high power CO2 laser systems, in medical applications and thermal imaging equipment.

You can order the different ZnSe optics from CVD ZnSe material. Crystaltechno Ltd. offers the manufacturing of ZnSe optics (in detail please see Catalog):
  • ZnSe windows (round and rectangular windows, plane parallel plates, protective windows and plates)
  • ZnSe wedges (wedged windows)
  • ZnSe spherical lenses, ZnSe cylindrical lenses, ZnSe meniscus lenses
  • CO2 laser optics: AR/AR coated ZnSe plane parallel windows, AR/AR coated ZnSe wedges, ZnSe Brewster windows, AR/AR coated ZnSe meniscus lenses, ZnSe output couplers (partial reflector or output mirror)
  • ZnSe prisms: ZnSe right angle prisms, ZnSe Dove prisms, ZnSe ATR prisms, ZnSe ATR hemispheres (ATR - Attenuated Total Reflection)
  • Different Zinc Selenide optical blanks, custom cut-to-size blanks, sheets with inspection polishing, SMTY (Sufficient Material To Yield) material and leftovers from CVD grown ZnSe material, namely: ZnSe unpolished blanks, plates, planks, bits, pieces, ingots, disks, ZnSe sheets, bars, slabs, ZnSe raw material, ZnSe growth crystal, ZnSe SMTY material or SMTY optical blanks, ZnSe waste.
Perhaps you will find required ZnSe optics at our stock, please see item Optical Crystals.

 
 
 
Blanks
Windows
Wedges
ATR Prisms
ATR Hemispheres
Plano-Convex Lenses
Bi-Convex Lenses
Bi-concave lenses
Meniscus
Cylinder Lenses
Right Angle Prisms
Dove Prisms
Output CO2 Laser Mirrors
Polished Domes


ZnSe optical lenses by Crystaltechno

CVD ZnSe polished domes and ZnSe optics by Crystaltechno

ZnSe large windows by Crystaltechno

CVD ZnSe growth polycrystalline material by Crystaltechno.JPG

ZnSe CO2 resonator by Crystaltechno

 
  (c) Crystaltechno Ltd. Vernadskogo 113-106, Moscow 119571, Russia
+7 (495) 234-5951, 234-5952, 956-7610
fax +7 (495) 433-1551
sales@crystaltechno.com
Site suggestions: webmaster@crystaltechno.com