| 摘要 |
A reflection mirror (22B) that causes an illumination light (LB1) to be incident on a movable scale (24) is oscillated in an X-axis direction based on a modulation signal (V(t)). Accordingly, the optical path of the illumination light (LB1), of the illumination light (LB1) and another illumination light (LB2) generated at an index scale (20), periodically changes, and as a consequence, the illumination light (LB1) is periodically modulated. Accordingly, an extra scanner that scans the illumination light (LB1) or another illumination light (LB2) with respect to the movable scale (24) does not have to be arranged, which allows an apparatus to be reduced in size and cost. |
