| 摘要 |
PURPOSE:To enable to make a piece of mirror block having a ring form groove sufficient by a method wherein only one mirror of a plurality of mirrors which compose a photo closed loop is formed in a structure wherein the alternations of advance-retreat direction and angles can be performed. CONSTITUTION:When the mirror block 3b is decided as a just plane mirror, and the ring form groove 14 is formed in the mirror block 3c, the detector is so constructed that the length of an optical path is controlled by moving a mirror surface 3c' of the mirror block 3c wherein the ring form groove 14 is formed in advance-retreat direction by a means 11 of controlling the length of the optical path, and that the angle of the mirror surface 3c' is controlled by a lock-in control means adhered at a thin part formed in the mirror block 3c. For example, the case of construction by sticking ring form piezoelectric elements 16a and 16b on the back surface of a member 17 mounted on the back surface side of the mirror block 3c is shown. When the outside piezoelectric element 16b is so deformed as to expand by shrinking the inside piezoelectric element 16a, the member 17 deforms and thus makes the mirror surfaces 3c' project toward the inside the block. |
