Patent ID: 7330093

Claim:
An alignment apparatus comprising: a structure to be aligned; a moving member which has a magnetic member and moves in a first direction; and an electromagnetic actuator unit, arranged on the structure, which applies a force in the first direction between said structure and said moving member, said electromagnetic actuator unit having: (i) a first electromagnet actuator having at least a pair of electromagnets arranged to sandwich said moving member, the first electromagnet actuator generating an attractive force between the first electromagnet actuator and the magnetic member by a magnetic flux generated by each of the electromagnets; and (ii) a second electromagnet actuator having at least a pair of electromagnets arranged to sandwich said moving member, the second electromagnet actuator generating an attractive force between the second electromagnet actuator and the magnetic member by a magnetic flux generated by each of the electromagnets, wherein a first electromagnet is feedback-controlled on the basis of a deviation between a target position and an actual position of said structure, and a second electromagnet actuator is feedforward-controlled on the basis of a target position of said structure.