Optical fiber transducer driving and measuring circuit and method for using same

• US 4,936,679 A
• Filed: 11/12/1985
• Issued: 06/26/1990
• Est. Priority Date: 11/12/1985
• Status: Expired due to Term

• Current Assignee: Deseret Medical, Inc. (Becton, Dickinson & Co)
• Original Assignee: Becton, Dickinson & Co
• Inventors: Mersch, Steven H.
• Primary Examiner(s): Rosenberger, Richard A.
• Application Number:
  US06/797,299
• Time in Patent Office: 1,687 Days
• Field of Search: 356/41, 356/432, 356/433, 356/434, 250/373, 364/416, 128/634, 128/637
• US Class Current: 356/41
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: G01N 2021/3181 using LEDs
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence
• CPC Class Codes: G01N 2201/0621 Supply
• CPC Class Codes: G01N 2201/08 Optical fibres; light guides

Abstract

Disclosed in an optical fiber transducer system with energy generating means for transmitting pulsing energy at various frequencies to bidirectional couplers for each frequency. The couplers record the intensity and further transmit the pulsing energy to a wavelength multiplexer/demultiplexer. The wavelength multiplexer/demultiplexer combines the plurality of energy supply means into a single output for an optic fiber which includes an optical delay sufficient to time separate the pulsing waves of energy. Reflected energy is transmitted back through the same wavelength multiplexer/demultiplexer, bidirectional coupler so that the recorded intensity of transmission and reflectance are comparable without system influence. A method is also shown for use of an optical fiber system including the components set forth and the system requires the generation and combination of the various frequencies of energy in a multiplexer/demultiplexer, the delay for time separation and the detection in a bidirectional coupler of transmitted and reflected energy.

Claims

1. An optical fiber transducer system utilizing a single fiber optic for transmitting energy for measurement of a parameter of a test medium and for receiving the reflected energy from said medium for comparison;

characterized by

(a) a power supply;

(b) a first energy source connected to said power supply for emitting bursts of energy at a first predetermined color frequency;

(c) a second energy source connected to said power supply for emitting bursts of energy at a second predetermined color frequency;

(d) a wavelength division multiplexer, demultiplexer connected to said first and second energy sources for receiving said bursts of energy;

(e) said multiplexer/demultiplexer for maintaining the discrete color frequencies of said received first and second bursts of energy while combining them;

(f) said multiplexer/demultiplexer further transmitting said first and second bursts of energy while separating the reflected energy thereof into individual channels of each color frequency upon the return thereof;

(g) a single fiber optic connected to said multiplexer/demultiplexer for transmitting said bursts of energy at said first and second color frequencies to and into said test medium from said multiplexer/demultiplexer and for carrying the reflected energy thereof directly and only from said test medium to said multiplexer/demultiplexer;

(h) optical delay means connected to said single fiber optic for extending the distance of said transmitted and reflected energy of said combined first and second color frequencies for permitting time separation of said transmitted and reflected energy for the discrete measurement thereof;

(i) a detector connected to each of said first and second energy sources;

(j) each said detector for measuring and storing the level of energy for its specific predetermined color frequency during the transmission thereof, and for subsequently measuring the reflected energy thereof for comparing the degree of transmitted and reflected energy; and

(k) computer means for establishing the timing of said bursts of energy, and for receiving said detected level of transmitted and reflected energy for each color frequency for establishing the percent of reflected energy over said transmitted energy.

2. The optical fiber transducer system of claim 1 wherein said first and second color frequencies are about 660 nm and 840 nm, respectively, the test medium is blood in vivo, and the measured parameter is oxygen saturation.

3. The optical fiber transducer system of claim 1 wherein said fiber optic is in series with said optical delay means and the combination of same is long enough to allow the time necessary for said computer means to determine the transmitted and reflected energy by time delay separation between the two resulting from the increased distance of travel necessary for the transmitted and reflected energy pulses.

4. The optical fiber transducer system of claim 1 wherein said computer means triggers said power supply to establish said bursts of energy for the transmitted wave and compares that energy with the energy received from the reflectance of that wave.

5. A method for measuring a parameter of a test medium utilizing an optical fiber transducer system by comparing transmitted energy to and into said medium with the energy reflected solely from said test medium;

the steps which comprise

(a) triggering the signal for a power supply in accordance with at least two color frequencies of timed pulses;

(b) generating a pulsing supply of energy at predetermined color frequencies in response to said triggering step;

(c) emitting bursts of light energy at said predetermined color frequencies in response to said pulsing power supply;

(d) detecting in a first detecting step said bursts of light energy from said emitting step as they are transmitted;

(e) storing information from said first detecting step;

(f) multiplexing said predetermined transmitted bursts of light energy at said predetermined color frequencies from said emitting step into a common output;

(g) imposing a delay on said common transmitted output of distinct color frequencies from said multiplexing step;

(h) sending said delayed common output along a single fiber optic to and into a test medium;

(i) receiving said common output of distinct color frequencies reflected directly and only from said test medium through said same fiber optic;

(j) detecting in a second detecting step, and storing, said reflected color frequencies with the same detector from said first detecting step; and

(k) forwarding the detected information from said first and second detecting step to a computer so that the difference can be calculated for each color frequency.

6. An optical fiber transducer system utilizing a single fiber optic for transmitting energy for measurement of a parameter of a test medium and for receiving the reflected energy directly and only from said medium for comparison;

characterized by

(a) a power supply;

(b) at least two energy sources connected to said power supply for emitting bursts of energy simultaneously at different predetermined color frequencies for each said energy source;

(c) a wavelength division multiplexer/demultiplexer connected to said at least two energy sources for receiving said bursts of energy;

(d) said multiplexer/demultiplexer for maintaining the discrete color frequencies of said received bursts of energy while combining them;

(e) said multiplexer/demultiplexer further transmitting said received bursts of energy while separating the reflected energy thereof into two or more individual channels upon the return thereof with one channel for each color frequency;

(f) optical delay means connected to said multiplexer/demulitplexer for extending the distance of said transmitted and reflected energy of said two or more bursts of energy for permitting time separation of adjacent bursts of transmitted and reflected energy at specific color frequencies for the discrete measurement thereof;

(g) a single fiber optic element connected to said optical delay means for receiving said delayed transmitted bursts of energy and transmitting them to and into said test medium, and for receiving the reflected energy of said bursts of energy directly and only from said test medium;

(h) a plurality of detectors with one each connected to each of said energy sources;

(i) each said detector for measuring and storing the level of energy for its specific predetermined color frequency during the transmission thereof, and for subsequently measuring the reflected energy thereof for comparing the degree of transmitted and reflected energy; and

(j) computer means for establishing the timing of said bursts of energy, and for receiving said detected level of transmitted and reflected energy for each color frequency for establishing the percent of reflected energy over said transmitted energy.

7. The optical fiber transducer system of claim 6 wherein said fiber optic is in series with said optical delay means and the combination of same is long enough to allow the time necessary for said computer means to determine the transmitted and reflected energy by time delay separation between the transmitted and reflected energy of a single burst as a result of the increased distance of travel imposed by said optical delay means.

8. The optical fiber transducer system of claim 6 wherein said computer means triggers said power supply to establish said bursts of energy for the transmitted wave and compares that energy with the energy received from the reflectance of that wave resulting from that same burst.

9. The optical fiber transducer system of claim 6, further characterized by

(a) said single fiber optic element is disposable.

10. The optical fiber transducer system of claim 6, further characterized by

(a) a bi-directional coupler connected to each said energy source for detecting the intensity of said emitted burst of energy therefrom, and further transmitting said burst of energy to said multiplexer/demultiplexer.

11. The optical fiber transducer system of claim 6, further characterized by

(a) each said bi-directional coupler detects reflected pulsating energy waves.