Method of calibrating a reluctance actuator assembly, reluctance actuator and lithographic apparatus comprising such reluctance actuator

A lithographic apparatus arranged to transfer a pattern from a patterning device onto a substrate, the lithographic apparatus comprising:

• a movable object;
• and
• a reluctance actuator configured to move the movable object, the reluctance actuator comprising:
• a stator comprising:
• a stator yoke forming a closed magnetic path around a center space,
• a plurality of teeth in an X axis and Y axis of the reluctance actuator, each tooth of the plurality of teeth projecting from the stator yoke into the center space, and
• a plurality of coils, each coil of the plurality of coils being configured to generate a magnetic flux in respective ones of the teeth;
• and
• a mover arranged in the center space and displaceable relative to the stator yoke in the X axis and in the Y axis, the mover comprising a plurality of faces, each face of the plurality of faces facing a respective one of the teeth to form a gap between the mover and the respective one of the teeth, wherein actuation of at least one coil results in a force in at least one of the X axis and Y axis of the reluctance actuator, thereby displacing the mover relative to the stator yoke in the at least one of the X and Y axis.