窄间隙条件下基于光纤Bragg光栅的曲面位移测量

在充分利用光纤Bragg光栅既是敏感元件又是传光元件这一特点的基础上，提出一种在曲面空间间隙小于1 mm的窄间隙条件下，测量两曲面间相对位移的方法。设计一种矩形弹片式传感探头，利用其挠度与应变之间存在的对应关系，通过应变对光栅Bragg波长的调制，获得光栅Bragg波长偏移量与曲面位移之间的线性关系。通过双光纤光栅的应变差动成功消除了光纤Bragg光栅存在的温度干扰问题。结果表明，当曲面相对位移量在0.35～0.85 mm范围内时，测量系统的灵敏度达2.54 nm/mm，线性度优于1%。

DISPLACEMENT MEASUREMENT OF CURVE SURFACE IN THE NARROW CLEARANCE BASED ON FIBER BRAGG GRATING

Based on the characteristic of fiber Bragg grating used as sensing element as well as light-transmitting element,and on the linear relationship between the strain and deflection of the elastic element on simply supported condition,a novel measurement of relative displacement between the two curved surfaces in narrow curved space whose clearance is less than 1 mm is presented.Through the fiber Bragg wavelength modulated by strain of elastic element,the linear relationship between the Bragg wavelength shift and displacement of curved surface is obtained.The cross-sensitivity due to temperature is eliminated by using strain differential of elastic element.Results indicate that,when the range of relative displacement between the two curved surfaces is 0.35~0.85 mm,the displacement sensitivity of measuring system is 2.54 nm/mm,and its linearity is less than 1%.