Importance

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Abstract

A catadioptric projection objective with telecentric image space has a first objective part configured to image the pattern from the object surface into a first intermediate image, and having a first pupil surface, a second objective part configured to image the first intermediate image into a second intermediate image, and having a second pupil surface optically conjugate to the first pupil surface, the second objective part including a concave mirror having a reflective mirror surface positioned at or close to the second pupil surface, and a third objective part configured to image the second intermediate image into the image surface, and having a third pupil surface optically conjugate to the first and second pupil surface. The concave mirror is arranged coaxial with the first objective part to receive radiation from the object surface, a first deflecting mirror is arranged to deflect radiation reflected from the concave mirror towards a second deflecting mirror, and the second deflecting mirror is arranged to deflect radiation from the first deflecting mirror towards the image surface such that the image surface is parallel to the object surface. The projection objective has an immersion lens group having a convex object-side entry surface bounding at a gas or vacuum and an image-side exit surface in contact with an immersion liquid in operation, wherein the immersion lens group is at least partly made of a high-index material with refractive index n≧1.6 at the operating wavelength.

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First Claim