Patent ID: 7571793

Claim:
Active vibration isolation system arranged to isolate a payload ( 39 ) from earth movements, said payload ( 39 ) being supported by means of at least one spring ( 43 ) and used as an inertial reference mass, said system comprising: a mass ( 41 ) supporting said payload ( 39 ) by means of said at least one spring ( 43 ) and being supported by a base body ( 16 ; 51 ) via a further spring ( 45 ); a sensor ( 59 ) for sensing a displacement of said payload ( 39 ) relative to said mass ( 41 ) and generating a displacement signal, wherein the displacement signal is an indication of the change of distance (d 2 ) between the payload ( 39 ) and said mass ( 41 ); a controller ( 49 ) for receiving said displacement signal and generating a control signal based on said displacement signal; and an actuator ( 47 ) arranged in parallel with the further spring ( 45 ) between said mass ( 41 ) and said body ( 16 ; 51 ), said actuator ( 47 ) for generating an actuation force based on said control signal and applying said actuating force to said mass ( 41 ).