| 摘要 |
PURPOSE:To omit a stroboscope and to make it possible to perform digital measurement, by generating Moire fringes on the half part of a grating body in correspondence with the change in relative rotation displacement between two rotary bodies. CONSTITUTION:Gratings 5 of a first optical grating body 41 are linearly continued in the longitudinal direction. Gratings 6 of a second optical grating body 42 ar divided in one half part 6a and another half part 6b in the longitudinal direction. The phases of both half parts 6a and 6b are made different by e.g., 1/4 the pitch P of the gratings. When relative rotation is yielded between both rotary bodies 31 and 32 by the torsion of a transmission shaft member 1, Moire fringes, which are continued in a ring shape, are yielded in the rotating direction of the shaft member 1 by the gratings 5 of the grating body 41 and both half parts 6a and 6b of the gratings 6 of the grating body 42. A light beam is inputted from a light source 8 through a light projecting optical fiber 9. The reflected light beams from the outer surface of the shaft member 1 are guided to a pair of light detectors 111 and 112 through light receiving optical fiber 101 and 102. Based on the output signals of the light detectors 111 and 112, the generated times of the Moire fringes are digitally counted by a detecting circuit. Thus the torsional torque of the shaft member 1 is detected. |
