MOTION DAMPER WITH ELECTRICAL AMPLIFIER, AND LITHOGRAPHIC DEVICE WITH SUCH A MOTION DAMPER

摘要

A motion damper (1) with a first part (3) and a second part (5) which are mutually displaceable parallel to a damping direction (X). The first part (3) including a permanent magnet system (35), and the second part (5) including an electric actuator coil (25) which is positioned in the magnetic field of the magnet system (35). According to the invention, the motion damper (1) including an electrical amplifier (53) for amplifying an electric current generated in the actuator coil (25) under the influence of a movement of the actuator coil (25) in the magnetic field of the magnet system (35). Since the electric current is amplified, the interaction between the electric current and the magnetic field of the magnet system (35) provides a sufficient electromagnetic damping force with a substantially ideal linear damping characteristic. In a special embodiment, the motion damper including two substantially identical measuring coils (27, 29) which are arranged on either side of the actuator coil (25), and two mutually oppositely magnetized magnet systems (37, 39) for cooperating with the measuring coils (27, 29), while the amplifier (53) supplies the actuator coil (25) with a current which is proportional to a difference between the currents generated in the measuring coils (27, 29). The motion damper (1) is used in a lithographic device (57) for the manufacture of semiconductor substrates (75). The motion damper (1) serves to prevent vibrations of a plate (91) relative to a focusing unit (65) of the lithographic device (57), which plate (91) supports a position measuring system (87) of the lithographic device (57).