压电陶瓷发热对光纤光栅传感信号干涉解调的影响

Influence of Thermal Effect Caused by Piezoelectric Transducer on Interferometric Demodulation for Fiber Bragg Grating Sensor

对于光纤光栅传感的非平衡干涉解调技术,理论和实验均证实充当其驱动元件的压电陶瓷通电发热会引入热噪声,导致解调输出的相移信息中出现附加相移。为排除热噪声对解调结果的干扰,提出了将驱动元件从干涉装置中分离出来的新方案。对于无温度控制、有温度控制以及分离驱动元件的三种Michelson非平衡干涉解调装置,实验证实第三种方案不仅可根除热噪声的影响,且无需克服热惯性而达到新的热平衡。系统传感灵敏度的实验值为0.9609°/με,分辨率可达5.5nε。

A scanning unbalanced Michelson interferometer is used to act as a demodulator in fiber Bragg grating sensor system. Additional phase-shift, caused by thermal noise, is demonstrated to occur in the output of the interferometer theoretically and experimentally, when a piezoelectric ceramic （PZT） is acted as the driving element of the interferometer. To eliminate the thermal noise, a new method by separating the driving element from the interference device is introduced. Comparing with the conventional with/without temperature controlling interferomtric demodulation scheme, thermal noise is demonstrated to be disappeared experimentally in the new scheme, and there is also no thermal inertia needed to be overcome. The predicted resolution of the system is 5.5 nε, and the experimental sensitivity is 0. 9609°/με.