The occasion where the linearly polarized light which

摘要

PROBLEM TO BE SOLVED: To provide a simple-structured current measuring device which increases incident light quantity of a light receiving element. ;SOLUTION: The measuring device has an optical fiber sensor 12 which is placed around the outer periphery of a conductor 10 through which measured current I0 flows, and essentially measures Faraday rotation angle of linear polarized light which is rotated with magnetic field of the measured current I0 when linear polarized light which is entered from one end of the sensor 12 is reflected on another end. A first ferromagnetic Faraday element 14 and first calcite 16 are provided on one end of a fiber 12a. The element 14 rotates polarized plane of linear polarized light by 22.5°, is light transmittant type, and has a YIG block 14a and a permanent magnet 14b. A prism 18 and one end opening of a polarized plane holding fiber 20 are placed on the incident end side of the first calcite 16. The other end opening of the fiber 20 is placed on an optical axis of a second ferromagnetic Faraday element 26. The Faraday element 26 rotates the polarized plane of linear polarized light by 45°. A second calcite 28 is placed on the incident end side of the element 26.;COPYRIGHT: (C)1998,JPO