Demonstration of self-referenced fiber optic moisture and pH sensors using optical time domain reflectometry (OTDR)

Edgar A. Mendoza; James A. Sorenson; Allen Iossi; Zongjian Sun; Daniel P. Robinson; Robert A. Lieberman

doi:10.1117/12.260598

10 December 1996 Demonstration of self-referenced fiber optic moisture and pH sensors using optical time domain reflectometry (OTDR)

Edgar A. Mendoza, James A. Sorenson, Allen Iossi, Zongjian Sun, Daniel P. Robinson, Robert A. Lieberman

Author Affiliations +

Proceedings Volume 2836, Chemical, Biochemical, and Environmental Fiber Sensors VIII; (1996) https://doi.org/10.1117/12.260598
Event: SPIE's 1996 International Symposium on Optical Science, Engineering, and Instrumentation, 1996, Denver, CO, United States

Abstract

The authors are developing a family of distributed fiber optic sensors (DIFOS) for use in prevention and monitoring of corrosion in advanced structural components of aging aircraft. These sensors, based on optical fibers that are intrinsically sensitive to either water or changes in pH, will alert maintenance personnel to the presence of water in aircraft lap joint structures and other inaccessible critical areas. We have demonstrated that the distributed fiber optic moisture and pH sensors can detect and localize water and/or changes in the pH environment surrounding the fiber sensor with 10-cm spatial resolution. A dual- wavelength (850 nm and 1300 nm) optical time domain reflectometer (OTDR) was used to characterize the spatial sensitivity and resolution of 20-meter lengths of both the moisture-sensitive and pH-sensitive optical fibers. The results of the characterization efforts demonstrated conclusively the ability of these distributed sensors to detect and localize their respective target measurands within 10 cm, with built-in 'self-referencing' to distinguish between moisture (or pH changes) and spurious effect (e.g., fiber bending).

Citation Download Citation

Edgar A. Mendoza, James A. Sorenson, Allen Iossi, Zongjian Sun, Daniel P. Robinson, and Robert A. Lieberman "Demonstration of self-referenced fiber optic moisture and pH sensors using optical time domain reflectometry (OTDR)", Proc. SPIE 2836, Chemical, Biochemical, and Environmental Fiber Sensors VIII, (10 December 1996); https://doi.org/10.1117/12.260598

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