Reassessment of spatial resolution in Brillouin optical correlation-domain sensors

We analyze the spatial resolution of Brillouin-based correlation-domain sensing techniques, specifically Brillouin optical correlation-domain analysis/reflectometry (BOCDA/R), and present a refined equation that explicitly incorporates strain magnitude and fiber length. Using rectangular approximations for both the Lorentzian gain and beat spectra, we derive four equations indicating how actual resolution deviates from the nominal value. Results show that when the Brillouin frequency shift is below ∼165MHz or the fiber length is under ∼2.5% of the measurement range, the refined resolution remains close to the nominal value. However, for larger strains and longer fibers, resolution degrades significantly, requiring additional signal processing.