Patent ID: 6260282
Filing Date: 2001-07-17
Classification: G03F

Abstract:
A positioning apparatus comprising:a first stage;a position measurement system positioned near the first stage, said position measurement system providing a first stage position signal corresponding to the position of said first stage;a fine stage positioned above the first stage and coupled to at least one actuator, wherein said at least one actuator moves said fine stage in approximate synchronization with said first stage;a second position measurement system positioned near the fine stare, said second position measurement system providing a fine stage position signal corresponding to the position of said fine stage; anda fine stage controller connected with at least one actuator and receiving a fine stage trajectory command signal proportional to said first stage position signal, said fine stage controller generating a positional error signal corresponding to a position of the center of said fine stage and controlling said at least one actuator in response to said positional error signal for said center of said fine stage.