Fiber optic systems for sensing temperature and other physical variables

  • US 5,090,818 A
  • Filed: 04/30/1990
  • Issued: 02/25/1992
  • Est. Priority Date: 08/06/1982
  • Status: Expired due to Fees
First Claim
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1. A temperature measuring arrangement comprising:

  • (a) probe means including a photoluminescent material containing luminescent centers so characterized that, when excited with transient interrogating light of a wavelength or wavelengths within a pre-determined spectral range, they emit luminescence light from two excited electronic energy levels, one of them being higher than the other and having a higher rate of luminescence decay than that of said other level, the relative intensities of the luminescence light emitted from each of said two levels varying as a function of the probe means temperature, the intensity of the luminescence light emitted from said higher level increasing with increasing temperature within a pre-determined temperature range within which the quantum efficiency of the total luminescence emitted from said two levels is approximately invariant, the combined luminescence light emitted from said two levels continuing in time beyond the termination of the transient excitation light with a decay time of its intensity which decreases in a known manner with an increase in temperature within said temperature range;

    (b) a source of said interrogating light;

    (c) fiber optic means for directing said interrogating light to said probe means;

    (d) fiber optic means for directing a fraction of the intensity of the luminescence light emitted from said probe means to photodetector means; and

    (e) photodetector means for measuring the decay time of the luminescence emitted from said probe means, said luminescence decay time being an indicator of the probe means temperature.

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