Characterization on the distributed fibre optic sensors using a newly developed calibration system

This paper presents the characterization of four tight-buffered strain cables and one loose-buffered temperature cable for the distributed fibre optic sensing using a multi-function calibration platform developed in the laboratory. The calibration platform comprises of two units: 1) an aluminum rig, which can automatically change the tested cable strain condition with the resolution of 1 and the accuracy of 10; and 2) a water bath, which can uniformly change the submersed cable's temperature from 0–100 °C with the resolution of 0.1°C and the accuracy of 0.05 °C. Parameters that were tested to quantify the cable qualities are: the measurement accuracy, the measurement hysteresis during loading and unloading process, and the measurement's linearity of the measured Brillouin scattered frequency shift with regard to the input strain/temperature change. The quality of the five tested cables varied significantly and the sensing hysteresis was observed for several cables (e.g. temperature cable), which has to be considered in the future data analysis process when utilizing those sensing cables in the real site monitoring.