Patent ID: 7176671

Claim:
A current measuring apparatus comprising: an optical fiber sensor extended or looped around a conductor through which a current to be measured flows, linearly polarized light emitted from a light source and propagated through said optical fiber sensor having a plane of polarization rotated under a magnetic field generated by the current to be measured; a photoelectric converter for converting into an electrical value an angle of rotation of the plane of polarization of the linearly polarized light after it exits said optical fiber sensor; and a photocircuit disposed between said optical fiber sensor and said photoelectric converter, said photocircuit including a birefringent member for separating the linearly polarized light into an ordinary ray and an extraordinary ray by birefringence and outputting the ordinary and extraordinary rays in parallel relation to each other, said current measuring apparatus ftirther comprising: a plurality of optical fibers for transmitting the ordinary ray from the birefringent member of the photocircuit to said photoelectric converter, while transmitting the extraordinary ray from the birefringent member of the photocircuit to said photoelectric converter; and a maintaining means adapted to maintain said plurality of optical fibers with a gap of a predetermined size being formed therebetween, said plurality of optical fibers having ends and opposite ends said ends of the plurality of optical fibers being disposed in the vicinity of said birefringent member, and said opposite ends being connected to said photoelectric converter, said maintaining means comprises a gap maintaining member for maintaining said optical fibers parallel to each other with the gap of a predetermined size being formed there between, the ends of the plurality of optical fibers maintained in parallel by said gap maintaining member respectively receive the ordinary and extraordinary rays which are outputted in parallel from the birefringent member.