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Fiber optic grating sensor systems for sensing environmental effects

  • US 5,380,995 A
  • Filed: 10/20/1992
  • Issued: 01/10/1995
  • Est. Priority Date: 10/20/1992
  • Status: Expired due to Term
First Claim
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1. A sensor system to sense an environmental effect, said system including:

  • a light source producing a first light beam with a relatively broad band of frequencies therein;

    a first fiber grating connected to receive said first light beam and positioned for exposure to the environmental effect, said first fiber grating having;

    first periodic variations in its optical properties therealong, the instantaneous location of said first periodic variations being affectable by the environmental effect to instantaneously determine a first relatively narrow band width of frequencies reflected by said first fiber grating, said first fiber grating creating a second light beam from said first light beam whose frequency spectrum depends on the environmental effect;

    a first local optical filter connected to receive at least portions of said second light beam and positioned for isolation from the environmental effect, said first local optical filter being capable of reflecting a spectrum having a relatively narrow band width overlapping at least some of the frequency spectrum of said second light beam, so that upon exposure to said second light beam, said first local optical filter creates a third light beam whose intensity is representative of the environmental effect; and

    first detector means positioned to receive said third light beam and to produce therefrom a first electrical output representative of the environmental effect.

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