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Fiber-optic sensor with two different wavelengths of light traveling together through the sensor head

  • US 4,703,175 A
  • Filed: 08/19/1985
  • Issued: 10/27/1987
  • Est. Priority Date: 08/19/1985
  • Status: Expired due to Term
First Claim
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1. A fiber-optic sensing system comprising:

  • a light source emitting light of at least a first frequency and a second frequency;

    fiber-optic sensing head means, having channeling means comprising a single light path for both frequencies therethrough, for varying light of said first frequency channeled thereto as a function of an environmental parameter to which said fiber-optic sensing head means is subjected;

    detection means for detecting light of both said frequencies channeled thereto and for generating a detection signal indicative of sensed variations in the detected lightsensing fiber-optic channel means for directing light of both frequencies from said light source to said fiber-optic sensing head means and for directing light from said fiber-optic sensing head means to said detection means;

    coupling means in said fiber-optic channel means between said light source and said fiber-optic sensing head means to merge the light paths of said first and second frequencies of light into a single light path for both frequencies through said fiber-optic sensing head means;

    reference fiber-optic channel means for directing light of both frequencies from said light source to said detection means without passing though said fiber-optic sensing head means; and

    signal processing means coupled to said detection means for processing the signals generated from light channeled through said sensing fiber-optic sensing means and for processing the detection signal generated from light channeled through said reference fiber-optic channel means, said processing being carried out in order to generate an indicating signal that accurately indicates the value of said environmental parameter as a function of said variation in the first frequency of light received from said fiber-optic sensing head means as compared to said second frequency of light received from said fiber-optic sensing head means and to both frequency portions of light received through said reference fiber-optic channel means.

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