变温斜率与散射功率补偿的分布式光纤测温传感系统

Distributed Optical Fiber Temperature Sensor System with Variable Temperature Slope and Scattering Power Compensation

针对分布式光纤拉曼测温传感系统中存在的空间分辨率与传感距离相互制约的问题以及在单模光纤上应用信噪比低的问题,提出一种加大探测脉冲宽度、提高信噪比而保持空间分辨率不变的方法,同时实现长距离传感。通过分析脉冲光在光纤中的传输过程以及光纤变温段的温度变化规律,利用温度变化曲线斜率与后向散射光功率建立温度补偿方案。实验证明,使用脉宽为50 ns的脉冲光与10 ns脉冲光相比,信噪比由33.38 dB提升到39.58 dB,10 km光纤末端测温最大稳态误差由±2.0℃减小到±1.0℃,20 km光纤末端测温最大稳态误差由±4.0℃减小到±2.0℃,同时空间分辨率保持1 m不变。

Aiming at the problem of mutual restriction between spatial resolution and sensing distance in distributed optical fiber Raman temperature measurement sensing system and the low signal-to-noise ratio(SNR)in single-mode fiber,a method to increase the detection pulse width,improve the SNR while maintaining the spatial resolution unchanged was proposed,and longdistance sensing was realized.By analyzing the transmission process of the detection pulse light in the fiber and temperature variation regularity of the fiber temperature change section,a temperature compensation scheme was established by using the slope of the temperature change curve and the backscattered optical power.Experiments show that,compared with the original 10 ns pulse light,using the 50 ns pulse light can improve the SNR from 33.38 dB to 39.58 dB.The maximum steady-state error of temperature measurement at the end of the 10 km fiber is reduced from±2.0℃to±1.0℃,and the maximum steady-state error of temperature measurement at the end of the 20 km fiber is reduced from±4.0℃to±2.0℃,while maintaining the 1 m spatial resolution unchanged.