基于拉曼散射光动态校准的分布式光纤温度传感系统

Distributed fiber optic temperature sensor based on dynamic calibration of Raman Stokes backscattering light intensity

分布式光纤温度传感(distributed temperature sensor,DTS)系统进行温度测量时,参考光斯托克斯光强度随着温度的升高而增大,使信号光反斯托克斯光与参考光斯托克斯光强度的比值减小,测量温度小于真实温度,降低系统的测温准确度.本文提出并实验验证了一种新的动态校准法修正斯托克斯光信号,可有效减小斯托克斯光导致的测温误差,提高系统的测温准确度.该方法根据参考光纤中的实时斯托克斯光强分布,模拟出对应的整条光纤在参考温度环境中的斯托克斯光强度曲线,实现斯托克斯光的温度响应修正.实验结果表明,与传统温度解调方法相比,分布式光纤温度传感系统进行斯托克斯光动态校准后测温准确度最高提升4.3℃.与瑞利噪声抑制法联用后,测温准确度提高8.9℃.本研究为DTS系统进行高温环境温度监测提供了一种新的解决方案.

In a distributed fiber optic temperature sensing system,the intensity of Raman Stokes backscattering light serving as reference light increases with the increase of temperature,leading to measurement errors in the system.A novel method of dynamically calibrating Raman Stokes backscattering light intensity is proposed to improve temperature accuracy for distributed fiber optic temperature sensors.According to the real-time Stokes intensity distribution in the reference fiber,Stokes intensity curve of the whole fiber at a reference temperature is simulated,and the temperature response of Stokes light is corrected.The ratio of Raman anti-Stokes light intensity to the calculated Stokes light intensity is used to demodulate temperature along the fiber.The experimental results indicate that the temperature accuracy of the distributed optical fiber temperature sensor system after making the Stokes optical dynamic calibration is increased up to 4.3℃compared with that from the conventional method.And the accuracy of temperature measurement is improved by 8.9℃when combined with Rayleigh noise suppression method.This study provides a new solution for a distributed fiber optic temperature sensor system to monitor high temperature environment temperature.