Patent ID: 8363315

Claim:
A catadioptric projection objective for imaging an off-axis object field arranged in an object surface of the projection objective onto an off-axis image field arranged in an image surface of the projection objective while creating at least one intermediate image comprising in that order along a straight optical axis: a first imaging subsystem for imaging the object field provided in the object surface into a first intermediate image; a second imaging subsystem for imaging the first intermediate image into a second intermediate image; a third imaging subsystem for imaging the second intermediate image into a third intermediate image; a fourth imaging subsystem for imaging the third intermediate image onto the image plane; wherein the second subsystem includes a first mirror having a first continuous mirror surface and a second mirror having a second continuous mirror surface facing the first mirror surface; the third subsystem includes a third mirror having a third continuous mirror surface and a fourth concave mirror having a fourth continuous mirror surface facing the third mirror surface; at least two of the mirrors being concave mirrors having a concave mirror surface having a surface of curvature defining a mirror axis on the optical axis.