| 摘要 |
<P>PROBLEM TO BE SOLVED: To accurately drive a mobile. <P>SOLUTION: In an encoder system, a wafer stage WST holding a wafer W and moving within a predetermined plane and moving scales 44A-44D disposed practically in parallel with the inside of the predetermined plane are irradiated with beams from a direction crossing the predetermined plane, respectively, via a plurality of heads 48a-48k, thereby measuring positional information of the wafer stage WST. In a control system, the wafer stage WST is controlled on the basis of the measured information of the encoder system. The number of a plurality of heads 48a-48k confronted with the moving scales 44A-44D, among the plurality of heads 48a-48k, is changed by the encoder system and the control system, and among the plurality of heads 48a-48k, a head to be used for measuring positional information is switched to another head by moving the wafer stage WST. <P>COPYRIGHT: (C)2012,JPO&INPIT |
