| 摘要 |
PURPOSE:To hold a mirror position with high accurate at the time of stage movement without deforming the surface of a laser interferometer mirror by increasing the holding force for the laser interferometer mirror to an extent where a position shift corresponding to acceleration applied to the mirror is not caused. CONSTITUTION:The mirror 1 is held with a variable force integrally with an X stage 7 on a Y stage 8 which is moved and positioned and used for the reference of the positioning of the X and Y stages 7 and 8. Then an interferometer 18 detects the position of the mirror 1 to measure the positions of the stages 7 and 8. At this time, the mirror 1 is normally held by a leaf spring 2 with the weak force set so that its surface does not deform. Then when the stages 7 and 8 are accelerated or decelerated, large acceleration is applied to the mirror 1, so a necessary friction force is not obtained with the weak holding force. Here, a piezoelectric element 4 is driven to increase the quantity of displacement of the leaf spring 2, thereby increasing the holding force of the mirror 1. Thus, the position shift between the mirror 1 and a body 11 to be moved is eliminated. |
