Patent ID: 7202937

Claim:
A lithographic apparatus, comprising: a first object table configured to hold a patterning device; a second object table configured to hold a substrate; a projection system configured to transfer a pattern onto a target portion of the substrate; and a balanced positioning system capable of positioning one or both of the object tables in at least three degrees of freedom, the positioning system comprising: a balance mass, a bearing configured to movably supports the balance mass, a positioning actuator disposed within or upon the balance mass, the positioning actuator configured to position the one or both of the object tables in at least two degrees of freedom, the two degrees of freedom including translation in first and second directions, the first and second directions being substantially mutually orthogonal, and arranged so that a reaction force acting in opposition to a drive force exerted on the object table is transmitted to the balance mass, and a control system adapted to correct cumulative translation and yaw of the balance mass and comprising a plurality of motors, each motor configured to apply a force to the balance mass to at least in part correct cumulative translation and yaw of the balance mass.