基于级联长周期光纤光栅的光纤布拉格光栅振动传感器的动态解调

Dynamic Demodulation of Fiber Bragg Grating Vibration Sensor Based on Cascaded Long-Period Fiber Grating

提出一种基于级联长周期光纤光栅(CLPG)的光纤布拉格光栅(FBG)振动传感器动态解调方法。宽带光源发出的光经FBG反射后,进入到CLPG,经过CLPG调制后FBG反射光强会发生变化。通过温度测量实验对监测系统进行静态标定,再将FBG传感器粘贴于铝板表面,采用该系统监测简支铝板结构在低频和高频下的振动信号。系统采集到的动态信号时域波形及频谱与涡电流位移计的测量结果相吻合,表明该监测系统可实现2kHz以下的动态信号测量。

A dynamic demodulation method of fiber Bragg grating （FBG） vibration sensor based on cascaded long- period fiber grating （CLPG） is proposed. The light of broad optical source is reflected by FBG, then the reflected light entrances the CLPG. The intensity of reflected light of FBG changes after being modulated by CLPG. Monitoring system is calibrated by temperature-measuring experiment firstly. Then FBG is stuck on the surface of aluminum specimen, and wavelength change of FBG caused by vibration of the aluminum specimen in low and high frequence is monitored by the system. The acquired vibration signal and fast Fourier transform （FFT） of the experiment data agree with the signal of eddy current displacement meter. It is shown that the FBG dynamic demodulation based on CLPG can be used to monitor no more than 2 kHz dynamic signal.