High-precision FBG Displacement Sensor Based onSpiral Amplification Structure
ＹＡＮＧ Ｊｉａｌｉａｎｇ １ ,ＣＨＥＮ Ｓｉｊｉｅ １ ,ＸＵ Ｂｉｎｇ １,２,∗
College of Science, China Three Gorgs University, Yichang 443002, China;2. Physics Experimental Teaching DemonstrationCenter of Hubei Province, China Three Gorges University, Yichang 443002, China
Abstract: Taking advantage of the sensitivity of ultra-weak fiber Bragg gratings (FBG) to displacementchanges,a composite displacement measurement method based on mechanical amplification and fiber Bragggrating technology is proposed. A helical structure design is adopted, where a micrometer screw is used to rotatea coaxial disk to achieve amplification of minute displacements. The minute axial displacement (AL) isefficiently converted into the tangential displacement of the disk through two amplifications, with a theoreticalamplification factor of 615.8 times(N=2TR/P,R=49 mm,P=0.5 mm).Combined with the high sensitivity ofultra-weak FBG to strain,a high-precision conversion from displacement to strain to wavelength is achieved. Thesystem is based on the Bragg reflection principle(A =2na) ,and a real-time detection of the wavelength shiftAA of the FBG is carried out through a demodulation module,establishing a linear fitting relationship of AA =1 649.752 0AX +0.0668 (R2 = 0.998 4). Experimental results show that the system can achieve sub-micronresolution (minimum 553. 9nm), has good measurement repeatability ( wavelength standard deviation about0.016 nm), and possesses advantages such as resistance to electromagnetic interference and strongenvironmental adaptability, providing an innovative solution that is structurally simple, highly sensitive, andhighly practical for micro-scale displacement measurement.
