An achromatic anamorphic prism pair for the conversion of the elliptical output beam of a tunable diode laser to a circular beam. The achromatic design prevents a directional shift in the output beam with respect to the optical axis of the system laser wavelength is varied....http://www.google.com/patents/US5596456?utm_source=gb-gplus-sharePatent US5596456 - Achromatic anamorphic prism pair
