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报道了利用反射谱带宽调制和光强差分探测技术实现单一光纤光栅温变无补偿位移精确测量的新方法。设计了一种结构新颖的曲臂梁位移传感装置,结合光波导理论与材料力学原理分析了光纤光栅在高斯应变作用下光栅反射谱侧向梯度展宽的成因,理论推导了特殊结构梁在外力作用下光栅反射谱带宽/反射光强与压力之间的响应关系。光栅反射谱侧向梯度展宽的同时反射光强线性增加,利用光强差分检测方法消除光源出光抖动的影响,提高了位移测量精度。基于带宽调制的光纤光栅位移传感方法免受温度变化的影响,在-10℃~80℃的温度变化范围内,测量误差小于1.2%,实现了单光纤光栅温变无补偿位移测量。
This paper reports a new method of accurate measurement of uncompensated displacement of a single FBG by using reflection spectrum bandwidth modulation and light intensity differential detection. A new curved beam displacement sensing device with a novel structure was designed. Based on the optical waveguide theory and the material mechanics principle, the cause of the lateral gradient expansion of the grating reflection spectra under the Gaussian strain was analyzed. Grating reflection spectrum bandwidth / reflected light intensity and pressure response relationship. The lateral reflection gradient of the grating reflection spectrum increases linearly while the intensity of the reflected light increases linearly. The light intensity difference detection method is used to eliminate the influence of light source jitter and improve the displacement measurement accuracy. The bandwidth modulation-based fiber grating displacement sensing method is immune to temperature changes. The measurement error is less than 1.2% within the temperature range of -10 ℃ ~ 80 ℃, which achieves the uncoordinated displacement measurement of single fiber grating.