Patent ID: 7541699

Claim:
A lithographic apparatus comprising: a patterning device support constructed to support a patterning device, the patterning device being capable of imparting a radiation beam with a pattern in its cross-section to form a patterned radiation beam; a substrate support constructed to hold a substrate; a projection system configured to project the patterned radiation beam onto a target portion of the substrate, and an actuator configured to position one of the supports, the actuator including a magnet assembly comprising: a ferromagnetic member extending in a first direction; an array of magnetized poles of alternating polarity arranged adjacent to each other in the first direction and mounted on the ferromagnetic member, and a magnetized pole of said array of magnetized poles comprising a plurality of permanent magnets arranged to generate a diverging magnetic field towards the ferromagnetic member, each permanent magnet of said magnetized pole has a magnetic polarization having a non-zero component in the first direction and a non-zero component in a second direction substantially perpendicular to the first direction, and a coil assembly constructed and arranged to co-operate with the magnet assembly.