光纤Sagnac温度传感器信号检测技术

利用光纤Sagnac干涉仪的偏振非互易性PNR(Polarization Non-Reciprocity)可以实现对单温度点的高精度测量.传感头周围温度场的变化引起干涉仪光路中两相干光的相位差变化.通过分析温度传感器的测温原理,得到其输出的线性化模型.采用方波调制解调技术实现了对温度传感器光路系统输出的全数字信号检测.设计了以C8051F060混合信号微控制器为核心的全数字信号检测系统,实现其采样信号和调制信号的相位关系保持.16位高精度模/数转换器的电压采样值通过数字滤波及分段函数解算处理,得到测量温度值的数字输出.这种技术具有实现方便,便于数字化处理及时序控制等优点.通过-15~55℃的全温扫描实验得到的实验数据和理论曲线近乎重合,系统输入/输出成很好的线性关系,线性度达到了10^-3量级.实验研究表明这种温度传感器可以实现高精度的温度测量.

Signal detecting technique for Sagnac fiber-optic temperature sensor

A temperature sensor based on polarization non-reciprocity(PNR) in fiber-optic Sagnac interferometer(FSI) can measure the temperature of one point in high precision.The phasic subtraction of two light beams was shifted while temperature field around the probe changed.Analyzing the temperature measuring theory of Sagnac fiber optic temperature sensor,a linear output model was established.The all digital signal detection was based on square-wave modulation and demodulation.An all digital signal detecting system using C8051F060 as its core was completed.It can maintain the phase relation of sampling signal and modulating signal.Sampling signal achieved by 16-bit A/D converter was computed in digital method to get the output of measuring temperature.This technique has the advantages of convenient realization and digital operation.The experimental data achieved by temperature experiments agree with theory well.The input and output of system achieve a linearity of 10~(-3).Discussion shows that this kind of temperature sensor can reach high precision.