IR polished Al2O3 circular sapphire window panel 0.17-5.5um (Al2O3 window panel)
Sapphire Al2O3 can be well applied as an optical window material for UV, VIS, and NIR spectral bands due to its extreme toughness and strength. Sapphire has multiple growth modes. The Verneuil and Czochralski methods are commonly used for standard grade sapphire materials. Higher quality sapphire, grown and manufactured by Kyropoulos for electronic substrates, can achieve very high purity and excellent UV transmission properties. The usage range in IR is limited to about 5 μ m and encounters few difficulties at any optical level. It is in the ultraviolet range and must be observed carefully because the transmission from 140nm to 240nm is very sensitive to impurities and interstitial vacancies. Large pieces of sapphire can be made by ribbon growth. Sapphire has a slight birefringence, and the typical IR window is usually cut from the crystal in a random manner. There are also specific applications for birefringence where orientation is chosen. Usually, this is a "zero degree" material where the optical axis is at a 90 degree angle to the surface plane. Synthetic optical sapphire is not colored. *Please note that all manufacturers seem to have inconsistent actual numbers for thermal expansion!