Patent ID: 8879159

Claim:
A system, comprising: a projection objective configured to image radiation from an object plane to an image plane along a radiation path, the projection objective having an optical axis, the projection objective comprising: a plurality of optical elements along the optical axis of the projection objective, the plurality of optical elements comprising a last optical element and a penultimate optical element, the last optical element being the optical element of the plurality of optical elements which is closest to the image plane along the radiation path, and the penultimate optical element being the optical element of the plurality of optical elements which is second closest to the image plane along the radiation path, wherein: during use of the system, an immersion liquid is present between the last optical element and the image plane; the system is configured so that, during use of the system, a distance between at least two of the optical elements of the plurality of optical elements of the projection objective is varied to reduce at least one aberration induced by a change in a property of the immersion liquid; and the projection objective is a microlithography projection objective.