Decoupling of actuators for positioning an object

摘要

The invention provides an apparatus and a method for positioning an object coupled to a first support structure and a second support structure. A first actuator drives the first support structure along a first axis and a second actuator drives the first support structure along a second axis orthogonal to the first axis. A third actuator comprising a forcer and a stator is provided for driving the second support structure that is guided for movement relative to the first support structure along a third axis orthogonal to the first and second axes. The forcer is coupled to the second support structure and is movable with respect to the stator, and the stator is relatively stationary and decoupled from the second support structure.