| 摘要 |
<p>A controller tilts a mobile body at an angle of (alpha) from an XY flat surface in a periodic direction of gratings (39Y1, 39Y2), based on a measurement value obtained from an interferometer which measures a tilt angle of the mobile body (WST) from the XY surface. Then, based on the measurement values obtained from encoder systems (62A, 62C) before and after tilting and information of the angle (alpha), the controller calculates a quantity fluctuated from the Abbe's number of the grating surface to a reference surface (for instance, an image surface of a projection optical system) to be a positional control reference of the mobile body within the XY flat surface. Then, the controller drives the mobile body along the XY flat surface, based on the positional information, which is of the mobile body within the XY flat surface and measured by the encoder system, and on an encoder system measurement error corresponding to the mobile body tilt angle from the XY surface due to the quantity fluctuated from the Abbe's number on the grating surface.</p> |
