| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical angle measurement device that increases an allowance difference in positioning of constituent elements.SOLUTION: An optical angle measurement device includes: a cylindrical scale carrier 10 that is coupled to a first object; and a scan unit 20 that is coupled to a second object. A transmission type measurement reference instrument 11 is arranged in a cylindrical periphery along a part of the scale carrier. The first and second objects are arranged to be rotatable relatively to each other centering around a rotation axial line R. A light beam flux emitted from a light source 21 of the scan unit is spectroscopically split into two partial light beam fluxes 30 by a spectroscopic element 23, and the partial light beam fluxes pass through a first measurement reference instrument area of the measurement reference instrument 11 to be deflected in a rotation axial line direction, respectively, and become partial light beam fluxes 31 propagating in the cylindrical scale carrier. After crossing in the rotation axial line, the partial light beam fluxes are incident upon a second measurement reference instrument area to become partial light beam fluxes 32 propagating in a direction of a coupling element 24 as converging, and are deflected by the coupling element 24. A pair of the interfering partial light beam fluxes 32 to be overlapped by the coupling element become a single signal light beam flux 33 to propagate in a direction of a detection unit 25 installed backward.SELECTED DRAWING: Figure 1 |
