Patent ID: 8760625

Claim:
A lithographic apparatus, comprising: a support configured to support a patterning device; a substrate table configured to support a substrate; a projection system configured to project an image of a patterning device supported by the support onto a substrate supported on the substrate table; and an aberration detector configured to measure an aberration of the projection system, wherein the aberration detector comprises: a target supported by the support comprising a pinhole feature; an imaging device supported by the substrate table, configured to capture an image of the pinhole feature projected by the projection system; an actuator, configured to move the imaging device in a direction parallel to the optical axis of the projection system between a first position and a second position; and a controller configured to obtain respective images of the pinhole feature projected by the projection system from the imaging device in the first position and the second position and to obtain a representation of the aberration of the projection system from the respective images.