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  • Sapphire Windows
  • Sapphire Windows

Sapphire Windows

  • Exceptional mechanical strength and chemical resistance
  • High thermal durabilities excellent for harsh environments
  • Maximum diameter 300mm
  • Broad wavelength range from 150-5500nm
  • Blank substrates, AR-coated pieces, and precision windows are available
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Materials Sapphire crystals Diameter Range Max. 300mm
Aperture >90% Dimension Tolerance +0.0/-0.2mm
Thickness Tolerance +/-0.1mm Surface Quality Optional: 60/40, 40/20 or 20/10 S/D
Parallelism 30 arc sec Chamfer 0.3-0.5mmx45°
Coating No coating, or single layer MgF2 and other custom coating options

Basic Properties:

Transmission Range 0.17 to 5.5 μm Refractive Index No 1.75449; Ne 1.74663 at 1.06 μm
Reflection Loss 14% at 1.06 μm Absorption Coefficient 0.3 x 10-3 cm-1 at 2.4 μm
Reststrahlen Peak 13.5 μm dn/dT 13.1 x 10-6 at 0.546 μm
dn/dμ = 0 1.5 μm Density 3.97 g/cc
Melting Point 2040°C Thermal Conductivity 27.21 W m-1 K-1 at 300K
Hardness Knoop 2000 with 2000g indenter Specific Heat Capacity 763 J Kg-1 K-1 at 293K (4)
Dielectric Constant 11.5 (para) 9.4 (perp)at 1MHz Youngs Modulus (E) 335 GPa
Shear Modulus (G) 148.1 GPa Bulk Modulus (K) 240 GPa
Elastic Coefficients C11=496 C12=164 C13=115 C33=498 C44=148 Apparent Elastic Limit 300 MPa (45,000 psi)
Poisson Ratio 0.25 Solubility 98 x 10-6 g/100g water
Molecular Weight 101.96 Class/Structure Trigonal (hex), R3c

Single Crystals Sapphire (Al2O3) Windows, featuring broad optical transmission from 150-5500nm spanning from UV to MWIR spectrum, and robust mechanical/thermal properties, are excellent for applications involving harsh and variant environments or requiring a broad transparent wavelength range (e.g. windows of sensors and detectors, IR applications, etc.). 

The material's most distinguishing attribute is its unequaled mechanical strength, being the second hardest material after diamond, single sapphire crystals have a Knoop Hardness of 1800-2200, making the windows made from single crystals sapphire resistant in extreme to chemical corrosion and abrasions. Sapphire windows might be produced into thin optics without fracturing because of the tight internal covalent bonding of single crystal sapphire while demonstrating good thermal stabilities due to its high thermal conduction.

Shalom EO offers various forms of Optical Sapphire Windows including flat windows with parallel faces, rectangular windows, wedge windows, and other custom specifications. Large aperture sapphire windows with diameters up to 300mm are available, and surface qualities of 60/40, 40/20, and 20/10 Scratch/Dig are optional according to the precision requirements of your interest. In convention, our sapphire windows are z-cut in order to prevent birefringence.

Shalom EO’s blank sapphire substrates are highly transparent in the wavelength range between 2.5-4.5µm with an average transmission rate above 85%. Single-film MgF2 coatings and other AR coatings could be furnished to increase transmission. Precision sapphire windows requisite for laser systems are also procurable upon request. 

Transmission curve of the Sapphire windows (no coating)