A birefringent network can be formed from a pair of beam directing elements that sandwich a birefringent filter. One of the beam director elements can be a polarizing beam splitter and the other of the beam director elements can be a reflector or polarizing beam splitter. The polarizing beam splitters can be formed by an anisotropic material sandwiched between two isotropic pieces and can include optical films to couple both polarizations of light into and out of the beam splitters. The polarizing beam splitters also can be formed by anisotropic material on either side of an isotropic bow-tie piece, all of which is sandwiched a pair of isotropic pieces. A birefringent network also can be formed by a pair of bulk birefringent beam splitters sandwiching a birefringent filter. Little or no polarization mode dispersion occurs in these birefringent networks since all of the beams travel the same distances through the same elements.

 
Web www.patentalert.com

> Method and system for correction of intrinsic birefringence in UV microlithography

~ 00312