| 摘要 |
PURPOSE:To compensate a supporting force error due to the deformation of a support rod by enabling a counter weight to move in the axial direction of a mirror and adjusting its movement quantity. CONSTITUTION:A slide mechanism 12 is provided between the counter weight 11 and support rod 7 to move the counter weight 11 in parallel to the axis of the support rod 7, and the counter weight 11 and support rod 7 are coupled by a spring 13. Namely, the counter weight 11 is guided linearly by the slide mechanism 12 in the axial direction of the mirror 1, the counter weight 11 and support rod 7 are coupled by the spring 13, and the spring constant of the spring 13 is adjusted to adjust the movement quantity of the counter weight 11 by gravidity. Consequently, the supporting force error is prevented from being generated even if the support rod 7 deflects. |
