Active oscillation isolation system by means of a hysteresis-free pneumatic bearing

摘要

Method and arrangement for oscillation isolation by means of an air bearing. The electropneumatic valves (4) for the compressed-air supply to the air bearing are subjected to a dither signal. This causes additional vibration of the mass 1 to be isolated. A compensation signal transmitter (12) ensures that additional vibration of the mass (1) is suppressed, by controlling actuators (10). Overall, hysteresis effects are avoided in the control of the compressed-air flow.

主权项

1. An arrangement for oscillation isolation of a mass comprising:
an air bearing for supporting the mass, wherein the mass comprises a lithographic system; a device for supplying pressure to the air bearing, the device having a compressed-air source and a control valve for a compressed-air flow to be supplied to the air bearing; a pneumatic control loop for controlling a moving valve element of the control valve; an actuator for oscillation-suppressing support of the mass; a sensor for detecting the oscillation state of the mass; an oscillation suppression control loop for controlling the actuator as a function of the sensor; and a dither signal transmitter for transmitting a dither signal to both:
i) the control valve, in order to influence the movement state of the valve element, resulting in dither vibration of the mass being produced, andii) a dither compensation circuit; wherein the dither compensation circuit is for controlling, based on the dither signal from the dither signal transmitter, the actuator, in order to suppress the dither vibration of the mass, wherein the dither compensation circuit and the oscillation suppression control loop are connected to the sensor for detecting the oscillation state of the mass, and wherein the dither compensation circuit and the oscillation suppression control loop are connected via an addition element to the actuator for oscillation-suppressing support of the mass.