Patent ID: 7872731

Claim:
A lithographic apparatus comprising: a support constructed to support a patterning device, the patterning device configured to provide a radiation beam with a pattern in its cross-section to form a patterned radiation beam; a substrate table constructed to hold a substrate; a projection system configured to project the patterned radiation beam onto a target portion of the substrate; and a polarization changing element comprising at least two wedge-shaped optically active members configured to rotate a polarization direction of at least a portion of the radiation beam by a predetermined angle and an optical propagation length adaptor associated with the wedge-shaped optically active members to adjust the predetermined angle by moving at least one of the wedge-shaped optically active members with respect to another of the wedge-shaped optically active members, wherein the optical propagation length adaptor comprises at least two wedge-shaped non-optically active members configured to correct for a beam displacement, wherein the at least two wedge-shaped non-optically active members are arranged after the at least two wedge-shaped optically active members with respect to the propagation direction of the radiation beam.