Research On Torsion Angle Measurement System Based On Fiber Grating

Torsion angle is an important parameter of engineering test. As a small volume, light weight, high sensitivity optical fiber passive component, fiber Bragg grating is a new research hotspot in the torsion angle sensor research field. This article has carried on a further research on torsion sensing characteristics of the high birefringence fiber gtating and the fiber Bragg grating around the torsion angle measurement method.This paper starts with the coupled-mode theory, build the torsion angle sensor model of FBG and Hi-Bi fiber gtating. It designed the structure of double FBG torsion angle sensor, which can overcome the influence of temperature and has a simple structure. For the Hi-Bi fiber grating, the relationship model between the center wavelength variation of the polarization axis X of the grating and torsion angle is established, which can eliminate the instability light source and optical fiber microbend loss and aging effects on measurement results.Second, carried the Matlab simulation experiment on the fiber Bragg grating torsion angle sensor and the Hi-Bi fiber Bragg grating torsion angle sensor models, verified the correctness of the theoretical model. For the double fiber Bragg grating torsion angle sensor, get the relationship curve between the torsion beam and the resonant wavelength of two gratings through the simulation experiment. For high birefringence fiber grating, got the relationship between the center wavelength of X axis polarization and the torsion angle with the use of Matlab simulation.Finally, built the experimental system of the FBG torsion angle sensor, and tested the sensing performance, analyzed the error of experiment. The test results show that the fiber Bragg grating torsion angle sensor can realize torsion angle measurement.