提出并设计了一种基片式多纵模拍频光纤激光位移传感器, 利用谐振腔中不同模式之间的拍频信号实现传感, 可以监测物体微小位移。该传感器采用应变传感基片结构, 有效对光纤进行保护, 并能缓冲拉伸和压缩带来的形变, 增加传感器灵敏度。同时在原有多纵模拍频光纤激光器的基础上进行了改进, 使系统获得更高的信噪比。阐述了多纵模拍频传感器的测量原理, 设计制作应变片并搭建实验平台。实验选取4个不同拍频信号作为传感信号, 实验数据表明: 在0～30 mm范围内, 频率漂移基本呈线性变化, 线性拟合度最高可以达到0.999 4, 这与理论推导结果一致。由于拉伸平台的拉伸精度限制, 该传感器的测量精度为1×10-3 mm。经过反复实验表明, 该传感器具有良好的稳定性。

A kind of optical fiber laser displacement sensor with multi longitudinal mode beat frequency was proposed and designed. The sensor could be realized by using the beat frequency signal between different modes in the resonator to monitor the small displacement of the object. The sensor used a strain sensing substrate structure to effectively protect the optical fiber and buffer the deformation caused by stretching and compression, and increase the sensitivity of the sensor. At the same time, the original multi longitudinal mode beat fiber laser was improved, which made the system get higher signal-to-noise ratio. The measuring principle of multi longitudinal mode beat sensor was described, and strain gage was designed and built. In the experiment, four different beat frequency signals were selected as sensing signals. The experimental data show that the frequency shift is basically linear in the range of 0 to 30 mm, and the highest linear fitting degree can reach 0.999 4, which is in agreement with the theoretical results. Because the precision of the stretching platform is limited, the measuring accuracy of the sensor is 1×10-3 mm. Repeated experiments show that the sensor has good stability.