High-accuracy OFDR-type dynamic distributed strain measurement using phase integration coherence compensation method and interferometer base point shift

We developed a novel OFDR system with a new coherence compensation method. This method termed “Phase Integration Coherence Compensation,” uses a conventional interferometer to compensate for coherence degradation at any location on the fiber under test by calculating a reference interferometer signal of any delay fiber length. In addition, by dividing the measurement range in the distance direction and performing optimal coherence compensation for each divided region, high Rayleigh scattering spectral correlations are maintained over a wide range of the fiber under test. We achieved dynamic distributed strain measurements over 400 m with a spatial resolution of 50 mm and a strain resolution of 1.3 με. The strain distribution was measured in real time at a rate of 10 Hz, with a measurement error of 0.8 %. Moreover, we simultaneously demonstrated telemetry measurements by shifting the interference base point 130 m.