Abstract: A apparatus processes an object (19), such as a semi-conductor wafer at accurately controlled positions. The object (19) is supported by a working platform (12) that is moveable along a path. A suspension actuator part (14) attached to the working platform (12), contains a soft magnetic core (24) with poles facing the surface of a soft magnetic element (34) on the support structure along the path and a winding (20) for application of a current to generate a magnetic field that runs through the core (24) via the poles and returns via the soft magnetic element (34). A sensor (17) senses a measured position of the suspension actuator part (14) relative to the position reference element (16). A control circuit comprises an outer control circuit (40) and an inner control circuit (42). The outer control circuit (40) receives a sensing result and determines force set point information to regulate the measured position of the actuator part (14) to a required value.

Abstract: An actuator driver circuit comprises a drive signal source (60) and an electrical damping element (100) having a negative resistance connected in series with the drive signal source (60). A controllable switch is provided for selectively switching said electrical damping element (100) into or out of a signal path from a drive signal source output to a driver circuit output, in order to selectively amend the electrical damping of an actuator, especially to increase the electrical damping of a radial actuator or a focus actuator of an optical disc drive in case of loss of track or loss of focus, respectively.

Abstract: A displacement apparatus comprising a first part and a second part, which can be displaced relative to each other in first and second different directions. The apparatus being suitable for use in a lithographic apparatus for positioning the mask holder with respect to the projection beam and for positioning the wafer substrate table with respect to the patterned beam. The first part comprises a first and second coil system in which an alternating current is provided by a power supply. The second part comprises a conductive platen which is disposed in a zone in which a magnetic field is induced when power is supplied to the coil systems. The coil system and platen are arranged with respect to each other so that when currents are passed through the coils, a magnetic field induced in the platen causes displacement between the platen and the coils in the first and second different directions.