Catadioptric projection objective
View Patent ↗A catadioptric projection objective for imaging a pattern provided in an object plane of the projection objective onto an image plane of the projection objective comprises: a first objective part for imaging the pattern provided in the object plane into a first intermediate image; a second objective part for imaging the first intermediate imaging into a second intermediate image; a third objective part for imaging the second intermediate imaging directly onto the image plane; wherein a first concave mirror having a first continuous mirror surface and at least one second concave mirror having a second continuous mirror surface are arranged upstream of the second intermediate image; pupil surfaces are formed between the object plane and the first intermediate image, between the first and the second intermediate image and between the second intermediate image and the image plane; and all concave mirrors are arranged optically remote from a pupil surface. The system has potential for very high numerical apertures at moderate lens material mass consumption.
1. A catadioptric projection objective for imaging a pattern provided in an object plane of the projection objective onto an image plane of the projection objective comprising:
an optical axis;
a plurality of lenses and at least one concave mirror having a continuous mirror surface;
a first refractive objective part for imaging the pattern provided in the object plane into a first intermediate image;
a second catoptric or catadioptric objective part for imaging the first intermediate image into a second intermediate image; and
a third objective part for imaging the second intermediate image onto the image plane,
wherein the projection objective is an unobscured system having no pupil obscuration and
wherein the projection objective is configured so that an object field disposed on one side of the optical axis at the object plane is imaged into an image field at the image plane disposed on the opposite side of the optical axis with no change of chirality occuring between the object field at the object plane and the image field at the image plane.
2. Projection objective according to claim 1 ,
wherein a first concave mirror having a first continuous mirror surface and at least one second concave mirror having a second continuous mirror surface are arranged upstream of the second intermediate image;
pupil surfaces are formed between the object plane and the first intermediate image, between the first and the second intermediate image and between the second intermediate image and the image plane; and
all concave mirrors are arranged optically remote from a pupil surface.