Patent ID: 8023104

Claim:
A projection exposure apparatus, comprising: a birefringent retardation arrangement comprising a retardation element, the retardation element comprising: a first subelement comprising an optically positively uniaxial crystal material which has a first optical crystal axis; and a second subelement comprising an optically negatively uniaxial crystal material which has a second optical crystal axis and which is arranged along an element axis of the retardation element before or after the first subelement, wherein: the first crystal axis and the second crystal axis are disposed in a plane perpendicular to an optical axis of the projection exposure apparatus; the first crystal axis and the second crystal axis are either arranged at an angle of 0° ±5° relative to each other or at an angle of 90° ±5° relative to each other; and the projection exposure apparatus is a microlithographic projection exposure apparatus.