Patent ID: 7738232

Claim:
An alignment apparatus which aligns a movable body, said apparatus comprising: a plurality of actuators which drive the movable body, wherein said plurality of actuators include a first actuator which drives the movable body in a first direction and a second actuator which drives the movable body in a second direction perpendicular to the first direction, said first actuator including an electromagnet, which comprises a magnetic block having an E-shaped cross section and a coil wound around a central tooth of the E-shaped magnetic block, and a magnetic body, and which drives the movable body in the first direction by an attraction force acting between the electromagnet and the magnetic body; a control system which controls said plurality of actuators; and a plurality of magnetic flux detection units, wherein said plurality of magnetic flux detection units are positioned at teeth on both sides of the E-shaped magnetic block so as to allow said control system to obtain non-uniformity of the attraction force acting between the electromagnet and the magnetic body due to non-uniform intervals between the electromagnet and the magnetic body, wherein said control system compares outputs of said plurality of magnetic flux detection units to obtain the non-uniformity, and controls the second actuator based on a result of the comparison, so as to reduce a force in the second direction acting on the movable body when the first actuator drives the movable body in the first direction.