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

An optical fiber coupler comprising:

• fiber-optic sensing head means for affecting one frequency portion of light channeled thereto as a function of an environmental parameter to which said fiber-optic sensing head means is subjected;
• input fiber-optic channeling means for directing light of a plurality of frequencies including said one frequency along a single light path from a light source remaining together through said fiber-optic sensing head means;
• and
• output fiber-optic channeling means for directing said light of a plurality of frequencies including said one frequency away from said fiber-optic sensing head means.

In an environmental parameter measurement system that includes:

• (1) first and second light sources for generating light at first and second frequencies, respectively;
• (2) an optical sensing head for varying light of the first frequency channeled therethrough as a function of an environmental parameter to which said optical sensing head is subjected, and wherein light of the second frequency channeled through said optical sensing head is not so affected:
• and (3) optical detection means for detecting a desired parameter, such as intensity, of light directed thereto;
• a method for accurately measuring said environmental parameter comprising the steps of:
• (a) placing said optical sensing head in an environment where the optical sensing head is subjected to the environmental parameter that is to be measured;
• (b) channeling light of both said first and second frequencies through a single path said optical sensing head to said optical detection means;
• (c) measuring at said optical detection means, the desired parameter of the light of said first frequency channeled through said optical sensing head;
• (d) measuring, at said optical detection means, the desired parameter of the light of said second frequency channeled through said optical sensing head;
• (e) channeling light of both said first and second frequencies through a reference channel, without passing said light through said optical sensing head, to said optical detection means;
• (f) measuring, at said optical detection means, the desired parameter of the light of said first frequency channeled through said reference channel;
• (g) measuring, at said optical detection means, the desired parameter of the light of said second frequency channeled through said reference channel;
• and
• (h) generating an environmental parameter measurement signal that comprises the product of the measurements of steps (d) and (f) divided by the product of the measurements of steps (c) and (g).

An optical sensing system comprising:

• a light source emitting light of at least a first frequency and a second frequency;
• 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 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 light;
• first light direction means for directing light of both frequencies from said light source to said sensing head means and for directing light from said sensing head means to said detection means;
• coupling means between said light source and said 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 sensing head means;
• second light direction means for directing light of both frequencies from said light source to said detection means without passing through said sensing head means;
• and
• processing means for processing the signals generated from by said detection means and for generating an indicating signal therefrom that accurately indicates the value of said environmental parameter to which said sensing head means is subjected.

An optical sensing system comprising:

• a broad band light source for generating light having a spectrum of frequencies therein including at least a prescribed first frequency and a second frequency;
• sensing head means, having channeling means comprising a single light path for both frequencies therethrough, for varying light of said first frequency directed thereto as a function of an environmental parameter to which said sensing head means is subjected;
• detection means for detecting light of both said frequencies directed thereto and for generating a detection signal indicative of sensed variations in the detected light;
• light direction means for directing light of said plurality of frequencies from said light source to said sensing head means and for directing light from said sensing head means to said detection means;
• coupling means between said light source and said sensing head means to merge the light paths of said plurality of frequencies of light into a single light path through said sensing head means;
• and
• processing means for processing signals generated from by said detection means and for generating an indicating signal therefrom that accurately indicates the value of said environmental parameter to which said sensing head means is subjected.