ABSTRACT
In the case of distributed vibration sensing (DVS), the raw data can amount to several GB/s, and even after pre-processing to extract the usable information, the data rate can still exceed 10 MB/s per fibre. Monitoring problems where the entire measurand distribution must be acquired at every point naturally lend themselves to the distributed approach. The boundaries of the applications of multiplexed sensors and distributed sensors are further shifted by recent advances in very-high-spatial-resolution, but long-range, Brillouin sensors. The faint long gratings (FLOG) technology therefore combines the inscription process of an FBG with a fully distributed interrogation and an efficient use of the probe energy. In spite of a history of more than 30 years, the pace of development of distributed sensors shows no sign of abating. Another recent development is the recognition that the output of a distributed sensor is fundamentally a function of two variables, namely the measurement time and distance along the fibre.
