Claims
- 1. A reversible sensor for optical absorption and reflection of an interrogating optical pulse communicated through an optical fiber having an opaque tube and a transparent core, said reversible sensor comprises:
- an optical fiber end at a core end of said core of said optical fiber,
- an electron charge transfer reagent that forms intermolecular complex with a gas, said intermolecular complex associates during exposure to said gas and complex rapidly dissociates in the absence of said gas, said intermolecular complex association and disassociation is characterized by changing said optical absorption and reflection of said optical pulse causing amplitudinal changes of said optical pulse when reflected back through said optical fiber, and
- a medium integrally formed with said core end and for containing said reagent.
- 2. The reversible sensor of claim 1 wherein said electron charge transfer reagent is an electron acceptor compound,
- said gas is a hydrazine fuel, and
- said sensor is for detecting contemporaneous exposure concentration of said hydrazine fuel.
- 3. The reversible sensor of claim 1 wherein said electron charge transfer reagent is an electron donor compound,
- said gas is nitrogen dioxide, and
- said sensor is for detecting contemporaneous exposure concentration of nitrogen dioxide.
- 4. The reversible sensor of claim 1 wherein said optical fiber is cladded and said medium is porous glass longitudinally and integrally formed at an uncladded end region of said optical fiber end.
- 5. The reversible sensor of claim 1 wherein said medium is porous glass disposed at a distal end of said optical fiber end.
- 6. The reversible sensor of claim 1 wherein said optical pulse is a laser pulse having a wavelength between 650 and 1600 nanometers.
- 7. A system for detecting contemporaneous exposure of a gas over a wide area, said system comprising:
- a diode laser means for generating a laser pulse,
- a fiber optic network of optical fibers comprising opaque tubes and transparent cores connected to said diode laser means for communicating said laser pulse distributed within said wide area,
- a plurality of reversible sensor means distributed within said wide area for receiving said laser pulse and for absorbing and reflecting said laser pulse to provide a respective plurality of reflected returns amplitudinally changed by said plurality of reversible sensor means when reacting to said contemporaneous exposure of said gas through changes in optical absorption and reflection of said laser pulse by an electron charge transfer reagent disposed in said plurality of reversible sensors means, and
- a monitor means connected to said fiber optic network for receiving said plurality of reflected returns correlated to said respective plurality of reversible sensor means and for determining which ones of said plurality of reversible sensor means are contemporaneously exposed to said gas within said wide area.
- 8. The system of claim 7 wherein said laser pulse has a wavelength between 650 and 1600 nanometers.
- 9. The system of claim 7 wherein said gas is a hydrazine fuel, and said electron charge transfer reagent is an electron acceptor compound.
- 10. The system of claim 7 wherein said gas is a hydrazine fuel and said electron charge transfer reagent is a 2,4,7-trinitrofluorenone electron acceptor compound.
- 11. The system of claim 7 wherein said electron charge transfer reagent is an electron donor compound.
- 12. The system of claim 7 wherein said gas is nitrogen dioxide and said electron charge transfer reagent is a N, N, N' N' tetramethylpara-diphenylenediamine electron donor compound.
- 13. The system of claim 7 wherein said gas is nitrogen tetroxide and said electron charge transfer reagent is a N, N, N' N' tetramethylpara-diphenylenediamine electron donor compound.
- 14. The system of claim 7 further comprising
- fiber optic trunk means connected to said diode laser means for communicating said laser pulse to said fiber optic network,
- a pulser means for providing a reference pulse communicated to said diode laser means for activating said diode laser means to generate said laser pulse, said reference pulse further communicated to said monitor means for providing a time reference of said laser pulse, and
- a fiber optic coupler means connected between said fiber optic network and said fiber optic trunk means for communicating said laser pulse from said fiber optic trunk means to said fiber optic network and for communicating said plurality of reflected returns to said monitor means.
- 15. The system of claim 7 wherein said fiber optic network comprises an optical fiber having a plurality of fiber optical branches extending from said optical fiber at a plurality of points along said optical fiber, said plurality of optical fiber branches have said respective plurality of reversible sensor means located at respective distal ends of said optical fiber branches.
- 16. A method for detecting contemporaneous concentration exposure of a gas over a wide area, said method comprising steps of:
- generating a laser pulse,
- distributing a laser pulse through a distributive fiber optic network of optical fibers comprising opaque tubes and transparent cores to a plurality of distal end reversible sensors having an electron charge transfer reagent for absorbing said laser pulse and reflecting returns dependent upon contemporaneous concentration to said gas,
- receiving said returns,
- determining respective time displacements from said generation step until said receiving step for said returns,
- correlating said returns to said reversible sensors dependent on said time displacements,
- correlating said returns to respective ones of said reversible sensors by time displacement from said generating step to said receiving step,
- measuring amplitudinal changes of said returns caused by said contemporaneous concentration exposure to said gas, and
- determining the extent of said contemporaneous concentration exposure of said sensors disposed at respective points within said wide area.
- 17. The method of claim 16 wherein
- said laser pulse has a wavelength between 650 and 1600 nanometers,
- said gas is a hydrazine fuel, and
- said electron charge transfer reagent is an electron acceptor compound.
- 18. The method of claim 16 wherein
- said gas is nitrogen dioxide,
- said electron charge transfer reagent is an electron donor compound.
- 19. The method of claim 16 wherein
- said gas is nitrogen tetroxide, and
- said electron charge transfer reagent is an electron donor compound.
- 20. The method of claim 16 further comprising steps of,
- measuring amplitudes of said returns for said reversible sensors absent contemporaneous exposure to said gas,
- exposing said reversible sensors to a calibration concentration of said gas,
- measuring said calibration concentration,
- measuring amplitudinal changes of said returns correlated to said calibration concentration, and
- calibrating said reversible sensors to said calibration concentration correlated to said amplitudinal changes.
STATEMENT OF GOVERNMENT
This invention was made with Government support under contract number F04701-88-C-0089 awarded by the Department of the Air Force. The Government has certain rights in the invention.
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Number |
Name |
Date |
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4834496 |
Blyler, Jr. et al. |
May 1989 |
|
5315672 |
Padovani |
May 1994 |
|
5315673 |
Stetter et al. |
May 1994 |
|