In a single-mode-fiber probe type of interferometer, the effect of fiber coupling on the sensing performance is theoretically comprehensively investigated in order to analyze and improve the achievable sensing accuracy for nanometric sensing. In both direct and via-lens coupling schemes for the interferometer, the scale factors to deduce optical path length change from the measured phase are analytically and numerically examined in terms of deviation from the plane wave assumption of conventional use. It is manifested that the scale factor deviation is of considerable magnitude in the case of direct coupling, but, by the incorporation of suitable collimating optics for coupling, the degree of deviation can be drastically reduced to as small as typically ${10}^{- 8}$, supporting achievement of ultrahigh accuracy such as picometer in displacement sensing. The effect of reflector tilting is also addressed.

中文翻译：

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精确相位理论，可在考虑纳米级光纤耦合的情况下提高用于纳米传感的光纤探针干涉仪的精度

在单模光纤探针型干涉仪中，从理论上全面研究了光纤耦合对传感性能的影响，以分析和提高纳米传感可达到的传感精度。在用于干涉仪的直接和通孔透镜耦合方案中，根据与常规使用的平面波假设的偏差，对用于推断光路长度从被测相位变化的比例因子进行分析和数值检查。显然，在直接耦合的情况下，比例因子偏差是相当大的，但是，通过结合合适的用于耦合的准直光学器件，可以将偏差程度大幅度地减小到通常为$ {10} ^ { -8} $，支持位移传感器中的皮秒计等超高精度的实现。还解决了反射镜倾斜的影响。