Patent ID: 8289619
Filing Date: 2012-10-16
Classification: G02B,G03F

Abstract:
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: a first objective part for imaging the pattern provided in the object plane into a first intermediate image; a second objective part entirely composed of reflecting elements for imaging the first intermediate image into a second intermediate image; a third objective part for imaging the second intermediate image 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 images and between the second intermediate image and the image plane; and wherein the projection objective is an unobscured system having no pupil obscuration and wherein the projection objective includes only two mirrors.