Optical crystals are used as view ports to protect other components within an optical assembly, instrument, or laser. In certain applications, optical crystals are required to withstand harsh environmental conditions and provide high levels of performance and reliability. Sapphire crystal has several unique properties that make it the ideal material for these applications.

1. Synthetic Sapphire, the single crystal form of Al2O3, is one of the hardest materials ( 9 Mohs hardness). Because of its structural strength, the sapphire crystal can be made much thinner than other common optical crystals, with better transmittance performance.

2. High thermal stability and excellent thermal conductivity make the sapphire crystal suitable for the applications in high power. The loss in a sapphire crystal is less than in another common optical crystal.