Differential fiber optical sensor with interference energy analyzer

• Main Authors: SPIRIN VASILII V, SHLYAGIN MIKHAIL G, UDD ERIC
• Format: Patent
• Language: English
• Published: 28.11.2002
• Edition: 7
• Subjects: ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVEREDIN A SINGLE OTHER SUBCLASS; MEASURING; MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER,MECHANICAL EFFICIENCY, OR FLUID PRESSURE; MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHYSICS; TARIFF METERING APPARATUS; TESTING

A fiber optic sensor, which includes an interference energy analyzer, is used to measure strain and temperature distribution along a test fiber. The sensor includes the following: a plurality of double-Bragg grating elements positioned along a test fiber, a broadband light source which produces a broadband spectral profile that propagates along the test fiber, an optical filter that is able to change the parameters of the broadband spectral profile, an optical reflection detector, a fiber optic beamsplitter, and an interference energy analyzer. Each double-Bragg grating element consists of two weak Bragg gratings, separated by a distance unique to each element. The interference energy analyzer calculates the energies of the interference patterns, which are created by beams reflected from double-Bragg grating elements. The energy of the interference signal changes when the gratings in one element non-uniformly change its parameters due to non-equal temperature or strain influence on two gratings.