Lithographic apparatus and device manufacturing method

A lithographic apparatus having at least one optical column, the optical column comprising:

• a programmable patterning device configured to provide a plurality of radiation beams;
• a projection system configured to project the plurality of beams onto a substrate, the projection system comprising a plurality of lenses;
• a first actuator system, configured to move at least one of the lenses in a direction perpendicular to the optical axis of the projection system to scan the plurality of beams over a target portion of the substrate;
• a radiation beam expander, configured to project an image of the programmable patterning device onto the at least one lens;
• a second actuator system, configured to move the radiation beam expander in a direction parallel to the optical axis of the projection system;
• and
• a control system configured to control the second actuator system in order to control a focus between the substrate and the at least one lens to a certain position.