A vibration sensor based on Sagnac interferometer and fiber ring laser for fault diagnosis of bearing

Abstract A vibration sensor based on Sagnac interferometer and fiber ring laser (FRL) is proposed for fault diagnosis of bearing, and a sensing system of vibration is demonstrated experimentally. In the sensing system, the Sagnac interferometer based on single mode fiber- polarization maintaining fiber-single mode fiber (SPS) as a sensor is connected to FRL which performs as a filter. Because the transmission characteristics of the SPS is modulated by strain, intensity-modulated sensing is induced for output power of the FRL. Experimental result shows that the accurate frequency of the vibration signal within relative error of 1.0% can be obtained by the sensor. The proposed sensor has the advantages of low-cost, compact size, easy to be fabricated and excellent anti-interference ability, which has potential applications on the bearing fault diagnosis of rotating machinery.