A high-sensitive system of linear temperature sensing based on Raman Scattering with an error correction method

The traditional temperature measurement system used the ratio of stokes light and anti-stokes light to demodulate the temperature, and there was an error when the ratio used directly. The propagation speed of stokes light and anti-stokes light in the same fiber was different because of dispersion effect. The two kinds of reflected light were obtained by photoelectric converter at different time when the scattering occurred at the same place. Therefore, there was a time warping between the two signals after data acquisition. This phenomenon would lead to measurement error in the process of demodulating temperature. A new method of error correction for the distributed temperature measurement system was used to eliminate the signal dislocation by correcting the stokes signal. In the absence of correction, the antistokes signal peak and the stokes signal peak occurred in different place, which leaded to errors in the process of demodulating temperature. This correcting method was used. The demodulation error was reduced from 2.3 degrees C to 1.2 degrees C. The shortest time was 4.96s when detected temperature rise rate was not less than 5 degrees C./min in the case of 10km fiber carried by this system. It was showed that this technique could improve the performance of the traditional distributed fiber Raman temperature measurement system, and it would have a good aspect.