Chemically sensitive fiber optic cable

U.S. Patent Number: 5337376

Abstract: A chemically sensitive sensor capable of detecting changes in concentrations of ions, atoms, or molecules in a fluid environment in which the sensor is immersed or embedded comprises a thin clad optical fiber, which is coated with a polymer which is permeable to liquids and which contains a chemically sensitive material, and a light carrying fiber. The polymeric material has the ability to change color and/or absorbance when the concentration of the ion, atom, or molecule in the surrounding environment changes. The polymer will return to its original color and/or absorbance state once the concentration goes back to the original value. The color change or absorbance is detected through the core of the optical fiber which is connected to a photodetector. The coupling of the light into the sensing structure is obtained by using a core-only optical fiber, surrounded by a clad material, in addition to an external light source. Coupling of the external light beam with the polymeric coated fiber is obtained through microbending losses in reverse by spooling the coated fiber around the clad material. Changes such as pH, metal or other ion concentration, organic molecule concentration, and gas molecule concentration may be detected.

Inventors: Ravetti; Robert G. (Rancho Palos Verdes, CA), Dougherty; Thomas K. (Playa Del Rey, CA)

Assignee: Hughes Aircraft Company (Los Angeles, CA)

Application Number: 08/049,461

Issued: 1994-08-09

Expired: 2006-08-09

Classes: 385/12 ; 250/227.14; 340/619; 385/145

Field of search: 385/12,13,123,128,141,145 250/227.21,227.23,227.14,905,906,907,908 340/603,619,870.28 128/634

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