Patent ID: 7372633

Claim:
A lithographic apparatus comprising: a projection system comprising a plurality of optical elements configured to project a patterned radiation beam onto a target portion of a substrate, and having an aberration correction device disposed therein, the aberration correction device comprising: a first correction optical element having a first surface, the first surface having a first shape that is not rotationally symmetric about an optical axis, a second correction optical element along the axis having a second surface, the second surface having a second shape, the second shape being substantially complementary to the first shape, and an actuator arranged to adjust a relative rotational position, about the axis, of the first or second correction optical element; and a control circuit arranged to control the actuator to position the first or second correction optical element at a relative rotational position to at least partially compensate for an aberration induced by the effect of a temperature change in one or more of the plurality of optical elements caused by absorption of energy from the radiation beam.