A distributed temperature-sensing system based on FBG

A 32 points distributed temperature-sensing system based on the technology of FBG is presented. This system is reliable and the electromagnetic interference is avoided. It suffices to the measurement in harsh environments. The scanning demodulation is used here, which is built on the ground of the central wavelength of the measuring FBG. But the wavelength drifts with the ambience and this drift will cause some errors. Meanwhile, the inherent characteristics of PZT may affect the temperature measurement precision. So we use a thermal etalon reference filter to calibrate the FBG. The system works in the temperature between 0°C and 70°C and the average wavelength drift is 6.4pm. There are nine periods in the work of our temperature measurement system. The first one is the calibration period, in which the FBG is adjusted by the thermal etalon reference filter. The other eight periods are measurement periods. The eight light switches open in turn and are measured. Then the current temperatures of 32 points are obtained.