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Method and apparatus for optically measuring a current

  • US 4,564,754 A
  • Filed: 03/07/1983
  • Issued: 01/14/1986
  • Est. Priority Date: 03/08/1982
  • Status: Expired due to Term
First Claim
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1. An optical current measuring apparatus comprising:

  • a conductor for conducting a current under measurement;

    a Faraday effect glass disposed to link perpendicularly to said conductor and having at least two total reflection areas at corners thereof;

    a light source for directing a light to a light input section of said Faraday effect glass;

    a polarizer for linearly polarizing the light from said light source and directing the linearly polarized light to said Faraday effect glass;

    said linearly polarized light being reflected at said total reflection areas of said Faraday effect glass such that said linearly polarized light circulates around said conductor as linearly polarized light and emits from a light output section of said Faraday glass as linearly polarized light, whereby said current is measured based on a Faraday rotation angle of the light by a magnetic field created by said current flowing in said conductor;

    said total reflection areas of said Faraday effect glass being configured for enabling said linearly polarized light reflected thereat to circulate and be emitted from said Faraday effect glass as linearly polarized light;

    said Faraday effect glass being planar and having an opening through which said conductor extends;

    an analyzer disposed to face said light output section of said Faraday effect glass for splitting the light from said light output section into two light beams;

    a pair of condenser lenses disposed to condense said two light beams from said analyzer;

    a pair of optical fibers disposed to face said condenser lenses;

    a pair of light detectors arranged to receive lights transmitted through said optical fibers; and

    an arithmetic unit for calculating said Faraday rotation angle based on outputs from said light detectors.

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