Patent ID: 8780441

Claim:
A projection objective having an optical axis, the projection objective comprising: a plurality of optical elements arranged to image an object field arranged in an object surface of the projection objective onto an image field arranged in an image surface of the projection objective, the object field being entirely outside the optical axis of the projection objective, the image field being entirely outside the optical axis of the projection objective, and the optical elements forming: a first, refractive objective part configured to generate a first intermediate image from radiation coming from the object surface, the first, refractive objective part including a first pupil surface; a second objective part comprising at least one concave mirror configured to image the first intermediate image into a second intermediate image, the second objective part including a second pupil surface optically conjugated to the first pupil surface; and a third objective part configured to image the second intermediate image onto the image surface, the third object part including a third pupil surface optically conjugated to the first and second pupil surfaces, wherein: optical elements arranged between the object surface and the first pupil surface form a Fourier lens group that comprises a negative lens group arranged optically close to the first pupil surface; the Fourier lens group is configured such that a Petzval radius R P at the first pupil surface satisfies the condition: |R P |>150 mm; the negative lens group comprises a biconcave negative lens immediately upstream of the first pupil surface along a direction that the radiation propagates through the projection objective; and the projection objective is a catadioptric projection objective.