| 摘要 |
PURPOSE:To correct an optical path shift due to disturbance in both an elevation and a swivel direction, by arranging the movable point, fixed point, and movable point of the beam of one of two mirror gimbals at 90 or 180 deg. to those of the other mirror gimbal. CONSTITUTION:A beam passed through an optical path AB is reflected by a return mirror 17 and further reflected by a return mirror 18, thus changing the optical path to a direction CD by 360 deg.. In this case, the optical paths AB and CD are adjusted in prescribed elevating and swiveling directions at movable points 3-6 with fine adjusting mechanism of mirror gimbals 1 and 2. At this time, the arrangement of the movable point 3, fixed point 11, and movable point 4 of the mirror gimbal 1 is set at 90 deg. to the optical axis in the mirror gimbal 2 to cancel deviation in the optical path of the mirror gimbal 1 due to disturbance by that of the mirror gimbal 2. |
