Single crystal sapphire lenses are ideal for demanding applications (such as laser systems) and harsh environments 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 diamond and, because of their structural strength, sapphire crystal lenses can be made much thinner than other common materials. Chemically, sapphire is single crystal aluminum oxide (Al2O3) and is useful in a transmission range from 0.15 to 5.5μm.
