Sapphire (alpha-Al2O3 crystal) optical windows

Sapphire (alpha-Al2O3 crystal) is a synthetic material, with melting point 2040 C. It's single crystal. Sapphire crystals belong to the Rhombohedral class 3m system. Sapphire is a very hard material, chemically inert. Sapphire has a nice thermoconductivity. As well as a high dielectric constant and low loss tangent.

Sapphire crystals have transmission in a 0.18-5.5 microns range.

Applications: sapphire has a high dielectric constant and low loss tangent, making sapphire an ideal material for semiconductor, electrical and microwave applications, optical windows, including the scanners and sight windows, watch glasses and other

Sapphire windows specification

Standard precision Sapphire windows: Random & C- plane (0001)
Surface quality80/50 – 60/40
Flatness5 lambda@ 633nm per inch
Parallelism<3 arc min
Clear Aperture>85%

High precision Sapphire windows: C- plane (0001)
Surface quality40/20-20/10
Flatnesslambda/2 @633nm per inch
Parallelism20 arc sec
Clear Aperture>85%