Sapphire is a material with extremely high thermal conductivity, high hardness, scratch resistance, high-temperature resistance, and corrosion resistance. Since sapphire is one of the hardest materials used in optical components, it is commonly used to replace other optical materials to make optical lenses, optical window, UV and IR optical window, as well as to improve optical transmission properties.

Sapphire windows are used in a wide range of UV, visible, and NIR bandwidths, e.g. in instruments such as night vision infrared and far infrared scopes, night vision cameras, and instrumentation for satellites and space technology, as well as windows for high power lasers.