Anamorphic Prism

An anamorphic prism pair is a pair of prisms which is usually used for reshaping the profile of a laser beam. For example, the elliptical beam from a laser diode can be transformed into a beam with circular cross-section, as is needed for many applications, by using a prism pair as a beam expander for only one direction (e.g., the horizontal one). Of course, one can also just modify the ellipticity, or convert a circular beam into an elliptical one.

Diode lasers usually have elliptical beam profiles. In most cases, though, the shape of the circular beam is required, such as pattern matching with the external resonator to make the beam size adapt to the small aperture through the isolator. A deformed pair of prisms is used to transform an elliptical laser diode beam into an approximately circular beam to amplify an elliptical beam in one dimension.