A non-contact fiber Bragg grating vibration sensor

Abstract

A non-contact vibration sensor based on fiber Bragg grating (FBG) sensing has been proposed and studied in this paper. The principle of the sensor as well as simulation and experimental analyses are introduced. When the distance between the movable head and the measured shaft changed, the diaphragm deformed under magnetic coupling of the permanent magnet on the measured magnetic shaft. As a result, the center wavelength of the FBG connected to the diaphragm changed, based on which the vibration displacement of the rotating shaft could be obtained. Experimental results show that the resonant frequency of the sensor is about 1500 Hz and the working band ranges within 0–1300 Hz, which is consistent with the simulation analysis result; the sensitivity is −1.694 pm/μm and the linearity is 2.92% within a range of 2–2.4 mm. It can be used to conduct non-contact measurement on the vibration of the rotating shaft system.