APPARATUS FOR OPTICALLY MEASURING A CURRENT

摘要

A current is measured by making use of a rotation of polarization plane in a magnetic field, that is, a Faraday effect. A conductor under measurement is transversely inserted into a center opening of a Faraday effect glass which has at least two total reflection areas on a periphery thereof so that a light directed into the Faraday effect glass is circulated around the conductor and emitted externally. The light emitted from the Faraday effect glass is split into at least two light beams, which are converted to electric signals by photoelectric elements, and A.C. components contained in the electric signals are extracted and compared. The electric signals are corrected based on the comparison result. The present measuring apparatus and method attain high precision current measurement in a stable manner over an extended period.