后向拉曼散射材料色散的位置匹配法误差校正

Position matching method for correcting errors caused by chromatic dispersion of backward Raman scattering

分布式光纤拉曼温度传感器中存在的色散效应造成升温峰中心位置的测温结果偏高，特别在温度突变的情况下影响尤为严重。针对此问题，详细分析了分布式光纤拉曼温度传感器的色散效应引起的光纤中各点反斯托克斯光和斯托克斯光传输速度差异，提出了基于两路背向散射光功率数据位置误差的分段配对方法，将反斯托克斯光功率与比它早散射回的斯托克斯光功率适当配对，再代入温度解调公式进行解调，从而减小了温度测量误差。最后，利用3km分布式光纤拉曼测温系统进行了验证，实验结果表明，经过配对修正后，升温峰中心位置的温度测量误差减小了0．3-0．8℃。

The dispersion effect in the Raman temperature sensor of distributed optical fiber makes temperature measurement results rising in central position of the temperature peak, especially in the case of temperature mutation. To solve this problem, the difference of transmission speeds of hackscattered lights in optical fiber is analyzed in detail, which is induced by dispersion effect. A new method, called segmental matching, is proposed to decrease the influence of transmission speed difference in the temperature measurement, which matches two sets of power data of backscattered lights according to position errors. It matches power data of Anti-Stokes light with that of Stokes light which returns to the sampling end earlier. Then these matched data are used in demodulation equation to calculate the temperature so that error of temperature measurement is reduced obviously. At last, a distributed Raman temperature sensing system of 3 km optical fiber is set up to verify the method. Experimental result shows that the error of temperature measurement at the center of temperature rising peak is reduced by 0.3 - 0.8℃.