Patent ID: 6992755

Claim:
A positioning apparatus which moves an object, said apparatus comprising: a first plate unit that retains the object; a second plate unit that retains said first plate unit, said second plate unit composed of a ceramic material and comprising a rib and a plurality of side plates on a periphery of said second plate unit, wherein said rib extends from an intermediate region of one of said plurality of side plates to an intermediate region of another of said plurality of side plates, the intermediate region of each side plate of said plurality of side plates being separated from an end of said each side plate, wherein said second plate unit includes a third plate unit that determines a relative position of the object and includes a plurality of optical mirrors, said third plate unit composed of a same material as said second plate unit; a first actuator unit that moves the object with six degrees of freedom to a predetermined position by an electromagnetic force and a mechanism for supporting said second plate unit against gravity; a second actuator unit that moves said first plate unit in X and Y directions in long strokes; and a fourth plate unit that is moved by said second actuator unit and supports said first actuator unit and said mechanism for supporting said second plate unit against gravity.