采用弱反射光纤布拉格光栅的声波方向检测

Detection of Acoustic Wave Direction Using Weak-Reflection Fiber Bragg Gratings

提出一种用于声波方向检测的弱反射光纤布拉格光栅(WFBG)分布式传感器,并进行了实验验证。将两个相邻WFBG间的分布式传感光纤用于检测声波振动信号。两段传感光纤解调的信号相位差对应于声波到达的时间差,再由时间差计算得到声波方向。一段长50 m的传感光纤环放置于振动液柱内,测得其平均声压灵敏度为-155.10 dB(re rad/μPa);两段50 m的传感光纤分布放置在木地板上用于接收正弦声波,探测方向的均方根误差为1.35°。理论推导和实验结果表明,这种分布式传感器能够实现对声波方向的检测,与传统基底缠绕光纤结构相比尺寸超细,有望搭载在水下无人航行器上,实现对水下发声目标的探测。

In this study,we propose and demonstrate a distributed sensor based on weak-reflection fiber Bragg grating(WFBG)to detect the acoustic wave direction.Further,we utilize a distributed sensing fiber between two adjacent WFBGs to detect the sound vibration signals.The phase difference of the demodulation signals of two sensing fibers corresponds to the difference between the reaching times of the acoustic wave,and the sound direction can be calculated based on the time difference.A 50-m sensing fiber coil is placed in vibration liquid column,and the average sound pressure sensitivity is estimated to be-155.10dB(re rad/μPa).Two 50-m sensing fibers are distributed on the wooden floor.Sinusoidal sound signals are received,and the root mean square error of the detection direction is 1.35°.The principle deduction and experimental results prove that the acoustic wave direction can be detected using the proposed sensor.It is expected to be carried on an unmanned underwater vehicle to detect the underwater vocal target because of the smaller size of the proposed structure when compared with that of the traditional structure of the fiber twined on substrate.