研究了长周期光纤光栅（LPFG）谐振透射光谱对外界环境折射率变化的敏感特性，在此基础上提出了将混凝土内部钢筋周围环境折射率与LPFG光谱特性相结合的理论，设计了一种基于折射率测量的LPFG钢筋锈蚀监测传感器。采用LPFG透射光谱检测技术，获取钢筋锈蚀过程中混凝土内部不同折射率环境所对应的LPFG透射光谱曲线族，进而得到LPFG谐振峰波长与混凝土内部钢筋锈蚀程度之间的对应关系，其谐振峰波长随钢筋锈蚀量的增加而先向短波后向长波方向偏移。该方法对混凝土内部钢筋锈蚀状态进行直接监测，测量及传导光路实现全光纤化，无需化学试剂标记，可实现对钢筋锈蚀过程的在线、精确及远距离遥测。

The principle of a long-period fiber grating (LPFG) rebar corrosion sensor is discussed in detail firstly based on a sensitive characteristic that the resonance spectrum of LPFG changes with refractive index in external environment. The theory combining the refractive index around rebar in concrete and the resonance spectrum is proposed. Then, LPFG spectrum measurement technology is selected to obtain LPFG spectrum curves corresponding with different kinds of refractive index in concrete, and the relationship between the resonance peak wavelength and the state of rebar corrosion in concrete is obtained. The experimental results numerically show that the resonance peak wavelengths increase and then decrease with the increasing corrosion rates. This method which can directly monitor the state of rebar corrosion in concrete is simple and easy to operate. The measurement and transmission sections of the system are completely composed of optical fiber, which can avoid the electronic interference. There is no necessity to use chemical reagent to sign the solutions which are going to be degraded. In conclusion, the late-model LPFG rebar corrosion monitoring system can achieve a real time, rapid, accurate and long distance measurement.