| 摘要 |
<p>A controller uses two Z heads (ZsR, ZsL), which are positioned above a reflection surface (39Y, 39Y) installed on the +X end and the-X end of the upper surface of a table (WTB), to measure the height and tilt of the table (WTB). According to the XY position of the table (WTB), the Z heads to be used are switched from ZsR and ZsL to ZsR' and ZsL (or ZsR and ZsL'). On the switching of the heads, the controller applies a coordinate linkage method to set an initial value of the Z heads (ZsR' (or ZsL')) which are to be newly used. Accordingly, although the Z heads to be used are sequentially switched according the XY position of the table, measurement results of the height and the tilt of the table are stored before and after the switching, and it becomes possible to drive the table with high precision.</p> |
