A high speed, wide-range, high-accuracy positioning stage device for eliminating
errors due to deterministic elements such as variation of surface machining accuracy
of a bar mirror and for preventing error accumulation due to indeterminate elements
such as air fluctuations when switching between laser interferometers. When an
X1 laser interferometer as a first position measurement device and an X2 laser
interferometer as a second position measurement device are switched, at a place
at which at least two position measurement devices are activated, when a value
is handed over from the X1 laser interferometer, which was activated, to the X2
laser interferometer, which is to be activated, errors due to the effect of X-bar
mirror flatness and air fluctuations are found by a correction function for the
X-bar mirror and/or a table and the average of the measured values, and the value
of the X2 laser interferometer is corrected by a correction device such as a calculation device.