| 摘要 |
Provided is a current measuring device such that it is possible to reliably keep the fluctuation range for the ratio error in output to within a range of ±0.5% and such that assembly thereof can be simplified. The current measuring device is configured to include at least a light entrance and exit, an optical fiber for a sensor, a Faraday rotator, a first 1/4 wavelength plate, a second 1/4 wavelength plate, a polarization separator, a light source, and a signal processing circuit comprising a photoelectric conversion element. The optical fiber for a sensor has birefringence and comprises one end into which two circularly polarized light beams having different directions of rotation enter and another end that reflects the circularly polarized light beams that have entered. In addition, the phase difference of two linearly polarized light beams in the round-trip light path between the two 1/4 wavelength plates is compensated, and the Faraday rotational angle when the Faraday rotator is magnetically saturated is set to 22.5°+±° so that the fluctuation range for the ratio error in the measured value of the current to be measured is set to be in the range of ±0.5%. In addition, the crystal axes on the optical faces of the two 1/4 wavelength plates are set to be perpendicular or are set to be in the same direction. |
