Safety mechanism for a lithographic patterning device

A method for containing displacement of a patterning device connected to a movable support structure, comprising:

• containing said patterning device relative to the support structure along an xy plane of said patterning device using a x-directed stopping structure and a y-directed stopping structure;
• containing said patterning device relative to said support structure along a direction out of the xy plane of said patterning device using a z-directed stopping structure;
• and
• moving the x-directed stopping structure, or the y-directed stopping structure, or the z-directed stopping structure, or any combination thereof, to allow movement of said patterning device during an exchange of said patterning device,
• 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.

A mechanism for containing displacement of a patterning device connected to a movable support structure, comprising:

• a x-directed stopping structure and a 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
• a 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;
• and
• a connector configured to secure said patterning device relative to the support structure,
• wherein the z-directed stopping structure is moveable to allow movement of said patterning device during an exchange of said patterning device and configured to contain displacement of said patterning device in case of failure of said connector,
• 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.