PURPOSE:To measure the twist angle of a shaft to be measured having a complicated shape with high accuracy by utilizing laser beam, by providing a beam collector connected to a laser beam generator through an optical fiber to one end part of the shaft to be measured while providing a beam receiver having optical fibers provided thereto in a line to the other end part thereof. CONSTITUTION:Laser beam of a laser beam generator 1 straightly advances toward a beam receiver 5 through an optical fiber 4 and a beam collector 3 and irradiates either one of optical fibers 7 provided in the beam receiver 5 in a line. The optical sensor 6 connected to said optical fiber 7 transmits this beam signal to a beam-electricity converter 8 through a conductor 9 and treated in said converter 8 as quantity of electricity. By this method, the position receiving the irradiation of laser beam of the beam receiver 5 is detected and displayed by a twist angle display device 10. Therefore, when relative displacement due to torque is generated in the circumferential direction of the terminal end 2a provided with the beam collector 3 and the terminal end 2b having the beam receiver 5 secured thereto, it can be determined as the shift quantity of laser beam.
展开▼
