Lithographic apparatus and device manufacturing method

A measurement or inspection apparatus comprising:

• a system configured to measure or inspect an object;
• a base structure;
• an object support constructed to hold the object, the object support movably supported on the base structure;
• a balance mass configured to absorb a reaction force arising from movement of the object support;
• an actuator connected to the balance mass and the base structure, the actuator configured to apply a force to the balance mass and the base structure;
• a sensor configured to produce a first signal for a measured physical characteristic of the base structure;
• a sensor configured to produce a second signal for a measured physical characteristic of the balance mass;
• and
• a control system configured to determine, based on the first and second signals, a signal for the actuator to apply a force to the base structure and/or the balance mass.

A non-transitory computer readable medium comprising instructions that, upon execution by a computer system, are configured to cause the computer system to at least:

• obtain a signal for a measured characteristic of a base structure of a measurement or inspection apparatus, the measured characteristic corresponding to a disturbance, or its effect, acting on the base structure, wherein the base structure movably supports an object support constructed to hold an object and the measurement or inspection apparatus comprises:
• a system configured to measure or inspect the object, a balance mass configured to absorb a reaction force arising from movement of the object support, and an actuator connected to the balance mass and the base structure and configured to apply a force to the balance mass and the base structure;
• and
• determine, based on at least the signal for the measured characteristic of the base structure, a signal for the actuator to apply a force to the base structure and/or the balance mass.

A measurement or inspection apparatus comprising:

• a base frame;
• a system configured to measure or inspect an object and comprising an illumination system configured to illuminate the object with a radiation beam;
• a base structure;
• an object support constructed to hold the object;
• a positioning device configured to position the object support, the positioning device being supported by the base frame and comprising a balance mass configuration, the balance mass configuration comprising a balance mass movable relative to the object support and configured to receive a reaction force arising from movement of the object support by the positioning device;
• a sensor configured to sense a vibration caused by a torque exerted on the base frame;
• and
• an actuator configured to exert a force on the illumination system or the base frame, in response to the sensed vibration, in order to at least partly dampen the vibration.