We analyze the source of the position deviation and propose a demodulation recursive compensation algorithm to ensure a sub-millimeter resolution in improved optical frequency domain reflectometry. The position deviation between the geometric path and optical path changes with the temperature or strain, due to the elastic-optic and thermal-optic effects. It accumulates along the fiber and becomes large enough to affect the spectral correlation between the measured and reference spectra at the fiber end. The proposed algorithm compensates for the position deviation of each measuring point and aligns the measured spectra with its reference. The numerical and experimental results both reveal that the signal-to-noise ratio of the correlation is improved doubly and a sub-millimeter spatial resolution becomes available at a 30 m fiber end. The recursive compensation algorithm helps to restrain the correlation degeneration at the fiber end and promises an effective approach to a sub-millimeter resolution in optical frequency domain reflectometry.

中文翻译：

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亚毫米分辨率OFDR的位置偏差的数值分析和递归补偿

我们分析了位置偏差的来源，并提出了一种解调递归补偿算法，以确保在改进的光频域反射仪中达到亚毫米分辨率。由于弹性和光学效应，几何路径和光学路径之间的位置偏差随温度或应变而变化。它沿着光纤累积，变得足够大，以影响光纤端的测量光谱和参考光谱之间的光谱相关性。所提出的算法可以补偿每个测量点的位置偏差，并将测量的光谱与其参考对齐。数值和实验结果均表明，相关性的信噪比得到了双倍提高，并且在30 m的光纤末端可获得亚毫米的空间分辨率。