为了测量金属板材在拉伸作用下的微应变，设计了以中心波长为1550 nm的多模光纤宏弯损耗传感器为传感元件的轴向微应变测量系统。该传感器将多模光纤传感环垂直固定在被测板材上，当板材被拉神时，光纤传感环的弯曲损耗效应明显增强，导致背向瑞利散射光强发生剧烈波动。搭建了轴向微应变测量系统，根据光时域反射原理获得了背向瑞利散射的光强变化，从而计算出金属材料应变值，可实现分布式实时测量。实验结果表明,该多模光纤宏弯损耗传感器的弯曲敏感区半径约为3~6 mm，微应变测量范围约为500~3000 με，微应变测量精度约为40 με。

For the purpose of measuring micro strain of a stretched metal panel, a measurement system including a fiber sensor is designed, which works at 1550nm central wavelength. The fiber sensor is actually a small circle of multimode fiber, fixed vertically on surface of the metal panel. When the metal panel is stretched, the sensing circle produces strenuous bending loss effect, leading to violent fluctuation of light intensity of back Rayleigh scattering. The measurement system of axial micro strain is set up according to the principle of optical time domain reflectometer and the light intensity of back Rayleigh scattering is acquired so that the strain of metal material is calculated. It can also realize distributed and real time measurement. The experimental results show that sensitive radius range of the bending loss multimode fiber sensor is within 3~6 mm, calibration measurement range of micro strain is about 500~3000 με, measurement precision of micro strain is about 40 με.