Determination of small-region temperature variation with RDTS system

A novel measurement scheme is proposed, which is capable of detecting temperature variations in sensing fibers based on Raman scattering with centimeter-level spatial resolution. The problem of inaccuracy in temperature determination when the length of temperature variation region (TVR) is less than the minimum required length of the test fiber is overcome by a procedure including determining the TVR length firstly, calculating the area value from the measured temperature rise curve secondly, and obtaining practical temperature change at small-region TVR from the pre-calibrated relation between the temperature and the area value at different TVR lengths finally. Theoretical analysis and experimental measurement are presented, and the influence of the uncertainty of TVR length on the detectable minimum temperature variation is also discussed. As an example, the experimental result shows that temperature variation of 60 °C can be measured with an accuracy of ± 3 °C when the TVR length is as low as 16 cm. The proposed scheme can greatly increase the spatial resolution of the Raman distributed temperature sensing system and enhance its applications in various fields.