Editing Reflecting telescope (section)

====Ritchey–Chrétien====

{{Main|Ritchey–Chrétien telescope}}

The '''Ritchey–Chrétien''' telescope, invented by [[George Willis Ritchey]] and [[Henri Chrétien]] in the early 1910s, is a specialized Cassegrain reflector which has two hyperbolic mirrors (instead of a parabolic primary). It is free of [[coma (optics)|coma]] and spherical aberration at a nearly flat focal plane if the primary and secondary curvature are properly [[Figuring|figured]], making it well suited for wide field and photographic observations.<ref name="Sacek1">{{Cite web|work=Notes on AMATEUR TELESCOPE OPTICS|last=Sacek|first=Vladimir|title=8.2.2 Classical and aplanatic two-mirror systems|date=July 14, 2006|url=http://www.telescope-optics.net/classical_and_aplanatic.htm|access-date=2009-06-22}}</ref> Almost every professional reflector telescope in the world is of the Ritchey–Chrétien design.