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Fiber-optic current sensor with polarimetric detection scheme

  • US 7,692,420 B2
  • Filed: 10/22/2008
  • Issued: 04/06/2010
  • Est. Priority Date: 04/25/2006
  • Status: Expired due to Fees
First Claim
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1. A method for measuring a current comprising the steps ofsending left and right circularly polarized light waves at least once along a sensing fiber extending around said current,passing said right and left circularly polarized light waves through an optical retarder for generating two orthogonally linearly polarized returning light waves,sending a first part of said returning light waves to a first detector, a second part of said returning light waves to a second detector, characterized by the step ofsending a third part of said returning light waves to a third detector, wherein said first part of said returning light is passed through a first circular analyzer before impinging on said first detector, wherein said second part of said returning light waves is passed through a second circular analyzer before impinging on said second detector and having a polarization opposite to said first circular analyzer, and wherein said third part of said returning light waves is passed through a linear analyzer before impinging on said third detector,wherein said first detector generates a signal I+ and said second detector generates a signal I

  • and said third detector generates a signal IL, and knowledge of the three signals I+, I

    , IL allows to obtain the current even if the values for fringe visibility V and arriving optical power I0 are not known in advance.

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