Microlithographic projection exposure apparatus

An 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 respectively disposed in a plane perpendicular to an optical axis of the arrangement;
• 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;
• the first subelement and/or the second subelement have a thickness profile varying transversely with respect to the optical system axis;
• and
• the arrangement is a birefringent retardation arrangement.

An 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 respectively disposed in a plane perpendicular to an optical axis of the arrangement;
• 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;
• the optically negatively uniaxial crystal material is selected from the group consisting of sapphire (Al2O3) and lanthanum fluoride (LaF3);
• and
• the arrangement is a birefringent retardation arrangement.

An 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 respectively disposed in a plane perpendicular to an optical axis of the arrangement;
• 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;
• wherein the optically positively uniaxial crystal material comprises magnesium fluoride (MgF2);
• and
• the arrangement is a birefringent retardation arrangement.