| 摘要 |
PURPOSE:To enable a traveling mechanism to be simplified and an entire body to be compact by providing a prism so that a zero-order light and a first-order light which are emitted from an acoustic optical light modulator advance in the same direction mutually and a traveling mechanism for allowing an incidence portion to perform translation. CONSTITUTION:A prism 20 is placed on a light path of zero-order light or first-order light so that zero-order light and first-order light of a second laser beam which is emitted from an acoustic optical light modulator 6 advance in a same direction mutually. A traveling mechanism performs translation between a first position where the zero-order light enters optical fibers 10 and 16 and a second position where the first-order light enters a second optical fiber, thus enabling a block 21 which is provided with a shutter 9 and the prism 20 to be moved outside the light path of a zero-order laser beam 7 and a laser beam 8 when visually recognizing interference fringes generated at a spot O and the incidence portion 11 to performed translation so that the laser beam 7 enters the optical fiber 10 for simplifying the translation and miniaturizing an entire speed meter. |
