Wide-Range Fiber Bragg Grating Displacement Sensor with Temperature Compensation

Abstract

A novel Fibre Bragg grating displacement sensor based on the cantilever beam structure is designed in this paper. Two fiber gratings with different central wavelengths are symmetrically pasted on the both sides of the cantilever beam. When the free end of the cantilever beam is changed, the two fiber gratings are respectively subjected to tension and pressure, which lead to the drift of the gratings' center wavelength to the opposite direction. At the same time, the problem of cross sensitivity between temperature and displacement is solved. In addition, a smart device using to change the measuring range of the sensor is designed and it is also easy to assemble and disassemble, so the whole sensor can be widely used. The experimental results show that when the range is 30mm, the average sensitivity of the displacement sensor is 92.4pm/mm and the correlation coefficient is 0.999. While the range is 60mm, the average sensitivity of the displacement sensor is 47.7pm/mm and the correlation coefficient is 0.998.