Patent ID: 6856379
Filing Date: 2005-02-15
Classification: G02B,G03F

Abstract:
1. A polarizer for transforming a light beam incident along an optical axis into an exiting light beam that has a prescribed distribution of locally varying polarization states over its cross-section, the polarizer comprising: at least one birefringent element having a crystal axis and a finite axial thickness for generating a phase shift between mutually orthogonally polarized field components of transmitted light; the illuminated cross-section of said polarizer is subdivided into numerous zones; at least one of said zones is configured such that its transmission direction for light is inclined with respect to said crystal axis of said zone within said zone at an inclination angle greater than 0° and less than 90° and lies in a transmission plane defined by said transmission direction and said crystal axis; wherein the axial thickness of said zone and the inclination angle are adapted such that a difference in the optical path lengths of said field components within said zone corresponds to a prescribed relative retardation upon exiting said polarizer and the orientation of the transmission plane of every such zone is prealigned such that the desired, local, preferred polarization directions exist within that zone, whereby the prescribed distribution of locally varying polarization states is obtained exclusively by rotating the polarization state of the incident light beam, rather than by filtering.