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提出一种偏振光干涉的光纤光栅应变测量方法,该方法能解决光纤光栅应变和温度测量时的交叉敏感问题。对于钒酸钇晶体偏振光干涉仪,如果选择两个能使干涉仪产生180°相位差的不同中心波长的光纤光栅,一个用于应变测量,一个用于补偿温度,就能很好地解决光纤光栅应变测量时的温度交叉敏感问题。分析了构成偏振光干涉仪的晶体的厚度对应变偏差的影响。理论计算和试验结果显示,当晶体厚度为0.5 mm时温度对应变测量的交叉敏感现象被压缩到了1.6%,相当于0.13με/℃。进一步的仿真分析发现当晶体厚度为0.1 mm时交叉敏感现象将被压缩到0.08%,相当于0.0067με/℃。小的晶体厚度有利于减小交叉敏感现象,但小厚度的晶体加工困难,为此分析了双晶体结构的方案。
A polarization grating interferometry fiber grating strain measurement method is proposed, which can solve the problem of cross-sensitivity in fiber grating strain and temperature measurement. For yttrium vanadate crystal polarization interferometer, if the choice of two interferometer can produce 180 ° phase difference between the different center wavelength of the fiber grating, one for the strain measurement, one for the compensation of temperature, we can solve the optical fiber Temperature Cross Sensitivity in Grating Strain Measurement. The influence of the thickness of the crystals constituting the polarization interferometer on the strain variation was analyzed. Theoretical calculations and experimental results show that the cross-sensitivity of temperature to strain measurement is reduced to 1.6% at a crystal thickness of 0.5 mm, which corresponds to 0.13με / ° C. Further simulation shows that the cross-sensitivity phenomenon will be reduced to 0.08% when the crystal thickness is 0.1 mm, which is equivalent to 0.0067με / ℃. Small crystal thickness helps to reduce the cross-sensitivity phenomenon, but the small thickness of the crystal processing difficulties, for the analysis of the dual-crystal structure of the program.