Patent ID: 7466397

Claim:
A mechanism for containing displacement of a patterning device connected to a movable support structure, comprising: at least one x-directed stopping structure and at least one y-directed stopping structure, said x-directed stopping structure and said y-directed stopping structure configured to contain said patterning device relative to the support structure along the xy plane of said patterning device; and at least one z-directed stopping structure configured to contain said patterning device relative to said support structure along a direction out of the xy plane of said patterning device, wherein the x-directed stopping structure, or the y-directed stopping structure, or the z-directed stopping structure, or any combination thereof, is moveable to allow movement of said patterning device during an exchange of said patterning device, and wherein the x-directed stopping structure, or y-directed stopping structure, or z-directed stopping structure, or any combination thereof, substantially does not contact the patterning device when the patterning device occupies its nominal position relative to the support structure.