Schmidt–Cassegrain telescope

The Schmidt–Cassegrain is a catadioptric telescope that combines a Cassegrain reflector's optical path with a Schmidt corrector plate to make a compact astronomical instrument that uses simple spherical surfaces. == Invention and design == The American astronomer and lens designer James Gilbert Baker first proposed a Cassegrain design for Bernhard Schmidt's Schmidt camera in 1940.

Source: Wikipedia — Schmidt–Cassegrain telescope (CC BY-SA 4.0)