APPARATUS FOR DETECTING ANGULAR DISPLACEMENT, TORSIONAL DISPLACEMENT, ROTARY SPEED AND THE LIKE OF SHAFT DYNAMICALLY

摘要

PURPOSE: To detect the twist of a shaft in dynamic loaded state easily and inexpensively by providing a polarization light source that is directed toward a rotary member, a 1/4 wavelength delay plate, and a detector. CONSTITUTION: Light is propagated into a shaft 28 by an optical circuit including such light source 12 as a laser diode and light from the light source 12 passes through a linear polarizer 16 and advances along a light path 14. Light propagated along a light path 24 advances through one window part 30 and reaches one of four reflection surfaces of a quadruplex mirror 34. Incidence light from the mirror 34 enters a 1/4 wavelength delay plate 38, passes through the delay plate 38, and is reflected by a mirror 40. As a result, light passes through the delay plate 38 again and advances toward the mirror 34. Delayed light is reflected by a light path 50 using the mirror 34, is given to a beam splitter 20 and a polarization splitter 54, and is divided into a polarization constituent with 0 deg. along a light path 56 and a polarization constituent with 90 deg. along a light path 60. Then, the delayed light is detected by detectors 58 and 62, respectively, and the detected signal is sent to a signal processor 64.