Measurement of strain distribution at high temperature is of great importance both for academic research and industrial applications. This paper presents a fully-distributed fiber optic sensor for the measurement of strain distribution in high-temperature environment based on the pulse pre-pump Brillouin optical time domain analysis (PPP-BOTDA). A telecom grade single mode fiber (SMF-28e+) was used to sense and transmit strain information. The optical fiber was placed and heated in a furnace that is instrumented and precisely monitored with a thermocouple in the middle of the furnace. The strain sensitivity of the sensor was experimentally calibrated with a precision translation stage for controllable fiber elongation over a temperature range of 22 (room temperature) to 800 °C. The precision stage was controlled with an accuracy of ±0.5 μm and an operation range of 20 mm. A quantitative calibration relationship was obtained using curve fitting technique. The accuracy and repeatability of the sensor for strain measurement were ±25 με and ±32 με, respectively, over a temperature range of 22 to 700 °C. At approximately 800 °C, the sensor remained intact but greatly lost accuracy and repeatability. It demonstrated satisfactory thermal stability for three heating-cooling cycles from 22 to 800 °C and steady heating for 32 hours.
doi: 10.12783/SHM2015/358