×

Bragg grating temperature/strain fiber sensor having combination interferometer/spectrometer output arrangement

  • US 6,137,565 A
  • Filed: 05/06/1999
  • Issued: 10/24/2000
  • Est. Priority Date: 05/15/1998
  • Status: Expired due to Fees
First Claim
Patent Images

1. An arrangement for optically determining an absolute physical state variable in an optical fiber with the aid of an optical spectral analyzer for determining different Bragg wavelengths of fiber gratings which have different mean wavelengths and at which the light traversing the optical fiber is reflected, as well as means for calculating the absolute physical quantity from the determined Bragg wavelengths, comprising:

  • an optical spectral analyzer in the form of a spectrometer having an imaging, spectrally dispersive element;

    a first linear receiver arrangement;

    a first input light bundle being arranged with reference to said dispersive element such that the light spectrally dispersed at said dispersive element is projected onto said first linear receiver arrangement;

    a second linear receiver arrangement;

    an additional second input light bundle being directed onto said dispersive element in said spectrometer, whose spectrally dispersed light falls onto said second linear receiver arrangement, parallel to the first one;

    a broadband light source;

    said two input light bundles being fed light from said broadband light source which has been reflected by at least two optical fiber gratings with different mean wavelengths;

    an interferometer arrangement with phase modulation and different arm lengths being present at least in the light path of the second input light bundle upstream of the spectral dispersion by said dispersive element;

    said interferometer arrangement having an evaluation section which is arranged downstream of said second receiver arrangement assigned to said input light bundle;

    a signal processing module for determining the absolute Bragg wavelengths of the optical fiber gratings and for calculating a physical variable dependent thereon being connected downstream of said first receiver arrangement; and

    phase demodulation modules arranged downstream of said second receiver arrangement being provided for evaluating interferometer signals for determining relative changes in the Bragg wavelengths of the optical fiber gratings, and for calculating the relative changes in a physical quantity.

View all claims
  • 2 Assignments
Timeline View
Assignment View
    ×
    ×