Stage devices are disclosed for holding an object such as a reticle for
use in microlithography. An exemplary stage device includes a movable
object-holder that holds the object. At least one actuator moves the
object-holder. A position-detector determines a position of the
object-holder, wherein the position-detector produces a first position
signal whenever the object-holder is not holding the object and produces
a second position signal whenever the object-holder is holding the
object. A controller, connected to the position-detector and to the at
least one actuator, produces a first control signal upon receiving the
first position signal and a second control signal upon receiving the
second position signal. These control signals cause the at least one
actuator to place or hold the object-holder at a pre-determined position
whether the object-holder is not holding or is holding the object. The
controller also determines whether the object is not being held or is
being held by the object-holder based on whether the controller is
receiving the first position signal or the second position signal,
respectively.