Editing Abbe prism

{{Short description|Dispersive prism}}
In [[optics]], an '''Abbe prism''', named for its inventor, the German physicist [[Ernst Abbe]], is a type of constant deviation [[dispersion (optics)|dispersive]] [[prism (optics)|prism]] similar to a [[Pellin–Broca prism]]. 

==Structure==
[[Image:Abbe-prism.svg|right|thumb|290px|Abbe prism]]
The prism consists of a block of glass forming a right [[prism (geometry)|prism]] with 30°–60°–90° triangular faces. When in use, a beam of light enters face '''AB''', is [[refracted]] and undergoes [[total internal reflection]] from face '''BC''', and is refracted again on exiting face '''AC'''. The prism is designed such that one particular [[wavelength]] of the light exits the prism at a deviation angle (relative to the light's original path) of exactly 60°. This is the minimum possible deviation of the prism, all other wavelengths being deviated by greater angles. By rotating the prism (in the plane of the diagram) around any point '''O''' on the face '''AB''', the wavelength which is deviated by 60° can be selected.

The dispersive Abbe prism should not be confused with the non-dispersive [[Porro–Abbe prism|Porro–Abbe]] or [[Abbe–Koenig prism]]s.

== References ==
* {{cite book | author=Hecht, Eugene | title=Optics (4th ed.) | publisher=Pearson Education | year=2001 | isbn=0-8053-8566-5}}

[[Category:Prisms (optics)]]
[[Category:German inventions]]