Imaging optical system and projection exposure system for microlithography

摘要

An imaging optical system includes a plurality of mirrors that image an object field in an object plane into an image field in an image plane. At least one of the mirrors is obscured, and thus has an opening for imaging light to pass through. The fourth-last mirror in the light path before the image field is not obscured and provides, with an outer edge of the optically effective reflection surface thereof, a central shadowing in a pupil plane of the imaging optical system. The distance between the fourth-last mirror and the last mirror along the optical axis is at least 10% of the distance between the object field and the image field. An intermediate image, which is closest to the image plane, is arranged between the last mirror and the image plane. The imaging optical system can have a numerical aperture of 0.9. These measures, not all of which must be effected simultaneously, lead to an imaging optical system with improved imaging properties and/or reduced production costs.

主权项

1. An imaging optical system which during operation directs light along a path to image an object field in an object plane to an image field in an image plane, the imaging optical system comprising:
a plurality of mirrors positioned along an optical axis of the imaging optical system, where the plurality of mirrors direct the light along the path, wherein at least three of the mirrors have an opening through which the light passes, each opening is completely surrounded by a solid surface, and the imaging optical system forms at least one intermediate image between the object plane and the image plane, where the intermediate image that is closest to the image plane in the light path is located between the image plane and the mirror that is closest to the image plane along the light path.