Sapphire and Ruby half-ball (hemispherical) lenses feature a very short back focal length with the convenience of a flat surface for easy mounting. Sapphire features a high index of refraction and excellent broadband transmission characteristics. Ruby half-ball lenses are easier to see and therefore easier to handle for physical applications. The lenses are very chemically stable and are great for severe environments, high temperature applications, and applications requiring high melting points. Typical applications include fiber communication, endoscopy, microscopy, optical pick-up devices, and laser measurement systems.