【摘要】 对光纤Bragg光栅(FBG)液氮(77K)下的应变传感技术及应变特性进行了研究。实验和分析表明:常温下FBG反射谱中的单个中心峰在低温下会劈裂为多峰,它产生于光纤、粘贴胶和金属基底热膨胀系数间的差异引起的强烈非均匀热弹性应变,使常温下均匀的光栅变啁啾化。建立了多种技术手段,成功消除了低温多峰现象,并测得了FBG低温和常温下的应变传感特性。实验结果表明:FBG的应变灵敏系数与温度无关。更多还原

【Abstract】 The strain sensing properties based on fiber Bragg gratings(FBGs)at the liquid nitrogen temperature(77 K)were investigated.It was found that the single central peak in the reflection spectrum of FBGs at the ambient temperature is split into multiple peaks at the cryogenic temperature.This abnormality is attributed to the severely inhomogeneous thermo-elastic strain over the greeting of FBGs due to the mismatch of the coefficients of thermal expansion between the glass fiber core,epoxy adhesive and metal substrate,which transforms the original uniform grating into a chirped one.Some technologies were developed to eliminate the multi-peak phenomenon and,eventually,the strain responses of FBGs at the ambient and liquid nitrogen temperatures were measured.The experimental results show that the strain sensibility of FBGs is independent of temperature,which demonstrates that FBGs are excellent cryogenic strain sensors.更多还原