Compared performances of Rayleigh Raman and Brillouin distributed temperature measurements during concrete container fire test

We present a distributed fiber optic sensing scheme to study 3D temperature fields inside concrete containers submitted to fire. High spatial resolution (3cm to 13cm), temperature uncertainty better than 3°C and rapid measurements (in the minute range) were required. We thus compared advantages and drawbacks of three sensing chains, based on Rayleigh, Brillouin and Raman scatterings; such distributed measurements were also compared with thermocouples (up to 250 measuring points). Practical field implementation limits are also underlined. Fire tests are a promising application for distributed optical fiber sensors.