Wadsworth constant deviation system
OPTICS, A WAY TO MOUNT PRISMS OR GRATINGS ON A TURNTABLE
Constant Deviation Prism; Constant deviation prism
In optics, Wadsworth's constant-deviation prism-mirror system (or Wadsworth constant deviation mounting) is a method to arrange a prism or diffraction grating and a mirror on a turntable to ensure that rays of light emerge in a fixed direction. Typically, light entering via a slit is directed into the prism by a lens.