| 摘要 |
PURPOSE:To change an inter-reflecting face distance of both mirrors and to control optical path length by simple constitution, by independently changing at least one supporting point position, of each supporting point of a link mechanism for moving the first mirror and the second mirror. CONSTITUTION:The first and the second links 19, 20 are axially supported so as to be turnable by the first, the second and the third supporting points 16, 17 and 18, among the first supporting member 11 for supporting the first mirror 4, the second supporting member 12 for supporting the second mirror 5 and a bracket 10 on a structure member 15, an intersupporting point distance of both the links is made equal to each other, and when the supporting point 16 moves by a distance l, the supporting point 17 moves by l/2 in the same direction. When controlling the optical path length, it is executed by controlling a nut 34 of the bracket 10, for instance, when extending the optical path length, the supporting point 18 is moved in the direction for keeping it away from the supporting point 16. In this way, it is possible to change the inter-face distance of both the mirrors and to control the optical path length by simple constitution. |
