Method and apparatus for compensating for reaction forces in a stage assembly
AssigneeNikon Corporation
InventorDouglas C. Watson
Life of this patent
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Abstract
A stage assembly which includes a stage which moves on a base, where the base is suspended on a foundation, minimizes disturbance to the base caused by linear acceleration of the stage during its movement. Reaction cancellation forces are applied through the stage center of gravity, hence there is no uncancelled reaction moment and no disturbance of the base stability. The net reaction cancellation force is applied in line with the stage center of gravity and parallel to the stage direction of travel. Alternatively, the base is isolated from the reaction forces by a rigid linkage between the stage linear actuator and a foundation.
Claims15
A method for compensating for reaction forces on a base which supports a stage which rides on the base on at least one bearing, where the stage is accelerated on the base in a first direction, thereby exerting a reaction force and moment on the base, comprising the step of:
- exerting a compensating force on the base in a direction having an axis passing through a center of gravity of the stage and lying parallel to the first direction.
A stage assembly comprising:
- a base;
- a stage movable on the base in a first direction on at least one bearing;
- a stage actuator for accelerating the stage on the base, thereby exerting a force on the base;
- and
- a mechanism applying a compensating force on the base in a direction having an axis passing through a center of gravity of the stage and lying parallel to the first direction.
Dependencies are inferred from the claim text.