Patent ID: 8873022

Claim:
A method, comprising: exposing an exposure area of a radiation-sensitive substrate arranged in an image surface of a projection objective with at least one image of a pattern of a mask arranged in an object surface of the projection objective in a scanning operation, the scanning operation comprising moving the mask relative to an effective object field of the projection objective in a first scanning direction and simultaneously moving the radiation-sensitive substrate relative to an effective image field of the projection objective in a second scanning direction; and actively changing imaging properties of the projection objective during the scanning operation according to a time profile to dynamically change at least one aberration of the projection objective during the scanning operation, wherein: actively changing the imaging properties of the projection objective comprises dynamically varying a field curvature of the projection objective according to the time profile during the scanning operation; the projection objective comprises a first field element comprising a mirror having a reflective surface arranged in a projection beam path of the projection objective at a location that is optically close to a first field surface of the projection objective; and varying the field curvature of the projection objective comprises adjusting a surface profile of the reflective surface of the mirror from a single radius of curvature having a first value in an optically used area prior to adjusting to a single radius of curvature having a second value in the optically used area after the adjusting, to change an optical effect caused by the mirror in a spatially resolved manner, wherein the adjusting results in a single radius of curvature after the adjusting, the second value being different from the first value.