Sapphire Windows are manufactured from single crystal sapphire, making them ideal for demanding applications (such as laser systems) 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. Chemically, sapphire is single crystal aluminum oxide (Al2O3) and is useful in a transmission range from 0.2 - 5.5μm.

Common Specifications

Abbe Number (vd): 72.24

Birefringence (no-ne): 0.008 for Visible Light Orthogonal to Optical Axis

Clear Aperture (%): ≥90

Coating: Uncoated

Coefficient of Thermal Expansion CTE (10-6/°C): 8.8

Density (g/cm3): 3.97

Index of Refraction nd: 1.77

Orientation of Axis: Random

Parallelism (arcmin): ≤3.5

Poisson's Ratio: 0.27

Substrate: Sapphire (Al2O3)

Surface Flatness: 2λ(typical)

Surface Quality: 80-50

Surface Roughness (μm): 0.1 per Inch

Wavelength Range (μm): 0.2 - 5.5

Wavelength Range (nm): 200 - 5500

Young's Modulus (GPa): 435

Knoop Hardness (GPa): 1900

Features:

Transmission in 0.3-5.0μm, no absorption in 2-3μm 
Extremely hard and durable 
High thermal conductivity 
High bulk damage threshold

Note for Sapphire Window:

(1). Custom-made Sapphire windows at any size are available.
Besides round, Sapphire windows at shape of quadrate, triangular, or other polygonal are available
(2). Other thickness from 0.5mm to 50.0 mm is available upon request.
(3). Better bevel is available upon request.
(4). Windows with Anti-Reflective(AR)