Patent ID: 8922753

Claim:
An optical system having an optical axis, the optical system comprising: a polarization-influencing optical arrangement, comprising: a first polarization-influencing element comprising a first optically uniaxial crystal material, the first optically uniaxial material having an optical crystal axis perpendicular to the optical axis of the optical system, the first polarization-influencing element having a thickness that varies in a direction of the optical axis of the optical system; and a second polarization-influencing element downstream of the first polarization-influencing element in a direction light propagates through the optical system during use of the optical system, the second polarization-influencing element comprising a second optically uniaxial crystal material, the second optically uniaxial material having an optical axis perpendicular to the optical axis of the optical system, the second polarization-influencing element having a plane-parallel geometry, wherein: an orientation of the optical crystal axis of the first optically uniaxial material is different from an orientation of the optical crystal axis of the second optically uniaxial material; during use of the optical system, the polarization-influencing optical arrangement converts a constantly linear input polarization distribution of light incident on the polarization-influencing arrangement into an output polarization distribution having a direction of polarization that varies continuously over a light beam cross section; and the optical system is a microlithographic optical system.