光强检测型光纤光栅温变不敏感动态压力传感研究

报道了基于光纤光栅反射谱带宽调制和光强差分检测技术实现单一光纤光栅温变不敏感动态压力传感的新方法。设计了一种结构新颖的双孔梁压力传感装置,依据双孔梁有限元受力分析将光纤光栅准确定位于线性梯度应变区,压力作用下光纤光栅反射谱对称展宽,反射光强线性正比于压力变化。基于光波导理论和材料力学原理推导了线性梯度应变场作用下光栅反射谱带宽、反射光强与压力之间的响应关系。利用光强差分检测技术取代传统波长解调方法,简化解调过程的同时传感系统免受温变影响。实验表明,在-10~80℃的温度变化范围内,系统测量误差小于总量程(120kPa)的1.8%,动态响应速度约80Hz,重复测量系统输出稳定,具有较好的应用价值。

Light Intensity-Referred and Temperature-Insensitive Fiber Bragg Grating Dynamic Pressure Sensor

The temperature-insensitive fiber Bragg grating (FBG) dynamic pressure sensing based on reflection spectrum bandwidth modulation and differential optical power detection is proposed and experimentally demonstrated. A specially designed double-hole cantilever beam is presented to locate the FBG into the linear strain-gradient region, resulting in FBG reflection spectrum symmetrical broadening and optical power linear increasing with pressure enhancing. Based on the theory of optical waveguide and material mechanics, the causation of FBG spectrum broadening under the linear strain-gradient is analyzed, and the corresponding force-to-bandwidth broadening relation and force-to-optical power relation are formulized. By replacing the traditional wavelength demodulation with optical power detection technique, the demodulating process is simplified and immune to temperature variation. For a temperature range of -10～80 ℃, the measured pressure fluctuates less than 1.8% without any temperature compensation. The system acquisition time is up to 80 Hz for dynamic pressure measurement. The experiment demonstrates the system is stable and applicable.