US Patent 7259832 Lithographic apparatus and device manufacturing method

A method and a system for accurate positioning of an object are presented. An embodiment of the invention includes an electromagnetic actuator including a coil assembly. The coil assembly includes two coils that encloses a magnet assembly including a magnet that is magnetized in the direction of the generated force. The generated force is substantially constant over the operating range of the actuator. The actuator may further be equipped with a cooling body surrounding the coil assembly.