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Home > Products > Windows > Sapphire Windows

Sapphire (Al2O3) Crystals Windows

● Extreme surface hardness and chemical resistance

● Transmission wavelength range from 0.2 to 5.5μm

Chemically, sapphire is single crystal aluminum oxide (Al2O3) and is useful in a transmission range from 0.2 - 5.5μm, it is suitable for MWIR 3-5μm thermal imaging applications. Sapphire Windows are made from single crystal sapphire, they are ideal for demanding applications because of their extreme surface hardness, high thermal conductivity, high dielectric constant and resistance to common chemical acids and alkalis. Sapphire is the second hardest crystal next to diamonds and, because of their structural strength, sapphire windows can be made much thinner than other common dielectric windows with improved transmittance.

Features：

  • Features Extreme Surface Hardness Chemical Resistance
  • Transmits Wavelengths Ranging From UV to Mid-Infrared
  • Thinner and Stronger than Standard Glass Windows


Specifications of sapphire windows:

Transmission curve of sapphire window:

(no coating, @3-5um)

Material:

CZ, KY, HEM monocrystal sapphire

Dimension Range:

Dia. 0.3mm to 300mm, 1x1mm to 300x300mm

Dimension Tolerance:

+/-0.05mm, +0/-0.1mm

Thickness Range:

>0.2mm

Thickness Tolerance:

+/-0.05mm

Surface Quality:

10-5, 20-10, 60-40, 80-50 (MIL13830)

Surface Accuracy:

up to 1/4 lambda per 25@633nm

Parallelism:

1 arc min

Chamfer:

protective, 0.2 to 0.5x45 Degree

Coating:

no coating or AR coating

Proterties of sapphire crystal:
Physical and optical proterties

Transimission Range0.17 to 5.5um
Refractive IndexNo 1.75449; Ne 1.74663 @ 1.06um
Reflection Loss14% @ 1.06um
Absorption Coefficient0.3 x 10-3cm-1 @2.4um
Reststrahlen Peak13.5um
dn/dT13.1x10-6 @ 0.546um
dn/du = 01.5 um
Density3.97 g/cc
Melting Point2040 
Thermal Conductivity27.21 W m-1 K-1 @ 300K
Thermal Expansion5.6 (para) & 5.0 (perp) x 10-6/K
HardnessKnoop 2000 with 2000g indenter
Specific Heat Capacity763 J Kg-1 K-1 @ 293K
Dielectric Constant11.5 (para) 9.4 (perp) @ 1MHz
Youngs Modulus (E)335 GPa
Shear Modulus (G)148.1 GPa
Bulk Modulus (K)240 GPa
Elastic CoefficientsC11=496 C12=164 C13=115 C33=498 C44=148
Apparent Elastic Limit300MPa （45,000 psi)
Poisson Ratio0.25
Solubility98x10-6g/100g water
Molecular Weight101.96
Class/StructureTrigonal (hex), R3c

Typical applications:

  • Industrial and Medical OEM’s
  • Air and Gas Analyzers/Monitors
  • High Intensity Xenon Lamps
  • Cryogenic View Ports
  • UV and IR Windows and Lenses
  • Detector and Pressure Cells
  • Photodiodes
  • Bar Code Readers