Rayleigh-OFDR Strain Distribution Measurement of a Self-Standing Fiber-Gyroscope Coil

We used Rayleigh-Optical Frequency Domain Reflectometry (Rayleigh-OFDR or R-OFDR) technique to improve our understanding of the longitudinal strain distribution along the optical fiber of a quadrupolar sensing coil of a fiber-optic gyroscope (FOG). To characterize this strain distribution remains crucial to better control the thermal impact on bias performance of the gyroscope. We analyzed this effect for a 400 m-long fiber coil, exposed to a ramp of temperature between 0°C and 80°C. R-OFDR method appears as a very promising candidate to reveal the complex thermo-mechanical behavior of the fiber sensing coil, offering a distributed view of classically integrated quantities, such as proper frequency or scale factor, and an access to the longitudinal elastic strain of the fiber, that is a source of bias defects in FOG measurement.