| 摘要 |
PURPOSE:To prevent the occurrence of an optical axis dislocation even when the position is dislocated by the external vibration by arranging, symmetrically to the axis, a prism which has the inner angle of a cross section of 45 deg., is a parallelogram, and vertical to the surface for the central axis, and shifting this in the vertical direction. CONSTITUTION:A prism 11, which has the inner angle of a cross section of 45 deg., is a parallelogram and vertical to one pair of parallel sides for the central axis, is arranged symmetrically to the axis, and the interval of optical axis 21, 22 and 23 is made equal. When the optical axes 21 and 23 are connected, the prism 11 is shifted in the vertical direction to the central axis by the means 12, when the optical switch is changed over, the optical axes 21 and 23 are connected and even when the prism 11 receives the vibration from the external part and the position of the prism is dislocated, the optical axis does not dislocate. Consequently, the light attenuating ratio is smaller, the light leaking can be minimized.
|
