| 摘要 |
<p>PROBLEM TO BE SOLVED: To enhance the positioning accuracy of a stage and to shorten a positioning time for the stage by a method, wherein a prescribed vibration component is removed from output of an acceleration sensor and an obtained acceleration signal is added to a power amplifier, which drives the stage, via a filter having a proper time constant and the optimum gain. SOLUTION: Output of a detecting circuit 22 becomes one in which pitching, rolling and yawing components contained in an acceleration sensor 10 are removed from a sensor 10 and is turned into an acceleration signal in the purely horizontal direction of a surface plate 8. A surface plate acceleration feedback loop for adding this signal to a power amplifier 16 via a low-pass filter 17 having a proper time constant and giving an optimum gain to the filter 17 is constituted. With this constitution, although a vibration component unwanted for a positioning of a Y-stage 4 is caused by the drive of the Y-stage 4, the vibration component is will not be applied to the amplifier 16 via the surface plate acceleration feedback loop. As a result, the stage 4 acts so as not to disorder the positioning convergence of the stage 4.</p> |
