具有温度补偿功能的双匹配FBG振动传感系统研究

Research on a vibration sensor system with temperature compensation using double-matched FBGs

为了提高光纤Bragg光栅(FBG)振动传感系统的解调灵敏度和解调范围,消除环境温度对解调信号的影响,设计了一种具有温度补偿功能的双匹配FBG振动传感系统。系统采用两个中心波长对称地位于传感FBG两侧的透射式匹配FBG,建立了两个互补对称的传感通道,并利用差分原理实现振动传感。通过Matlab软件对系统性能进行了仿真分析,结果表明,与传统方法相比,本文方法有效地提高了系统解调灵敏度和解调范围。将匹配FBG与热电制冷器(TEC)集成封装,并建立温度补偿判断通道,当判断通道输出电压超过已设置好的阈值时,利用TEC改变封装环境温度,使匹配FBG与传感FBG中心波长重新匹配,实现系统温度补偿。经实验测试,系统的归一化解调灵敏度为5.168/nm,解调范围为1.2nm,判断通道的归一化阈值电压为0.890 5。在4种不同环境温度下,利用本系统对同一振动信号进行测量,实验结果验证了系统温度补偿的可行性。

In order to improve the demodulation sensitivity and range of fiber Bragg grating （FBG） vibra- tion demodulation system and eliminate the influence of ambient temperature on demodulation signal, a fiber Bragg grating vibration demodulation system with temperature compensation is developed. Using two transmission mode matching FBGs with center wavelengths symmetrically located at both sides of that of the sensing FBG, two symmetrical and complementary sensing channels are established in the system and then the vibration demodulation is realized based on difference principle . The system per- formance is simulated by Matlab software and the results show that compared with traditional method, the proposed method can effectively improve the demodulation sensitivity and range of the system. The matching FBGs are packaged together with a thermoelectric cooler （TEC） and a judging channel of tem- perature compensation is established. When the output of judging channel exceeds the threshold set pre- viously for temperature regulation judgment, the center wavelengths of matching FBGs are re-matched with the sensing FBG by changing the package temperature of matching FBGs with TEC controller, thereby realizing the temperature compensation of the system. The experimental results show that the normalized system demodulation sensitivity is 5. 168/nm, the demodulation range is 1.2 nm, and the nor- malized threshold voltage of judging channel is 0. 890 5. The feasibility of system temperature compensa-tion and judgment mechanism is demonstrated by measurement of the same vibration signal under four different environment temperatures using the developed demodulation system