Microwave interferometers have been attractive devices for high-precision measurements of displacement-related physical quantities in a variety of scientific and engineering applications. However, due to the long operating wavelength, the displacement measurement resolution of microwave interferometers is limited to the micrometer scale. In this article, we propose and demonstrate a novel technology based on microwave interferometry for displacement measurements with potential picometer resolution. An open-ended (OE) transmission line resonator based on a homemade hollow coaxial cable is explored in proof-of-concept numerical and experimental investigations. The technique involves two stages of displacement sensitivity amplification: one is the open end-based phase sensitivity amplification, and the other is the destructive interference-based phase sensitivity amplification. We experimentally demonstrate a wavelength sensitivity amplification factor of 1800 through spectral interrogation where only the open end-based amplification is involved, and a phase sensitivity amplification factor of 1.4 million through phase interrogation where both the open end-based amplification and the destructive interference-based phase shift amplification are involved, i.e., two-stage phase shift amplified microwave interferometry (TPAMI). The numerical investigations and the experimental results match well.

中文翻译：

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微波法布里干涉仪位移检测灵敏度的研究


微波干涉仪一直是各种科学和工程应用中与位移相关的物理量高精度测量的有吸引力的设备。但由于工作波长较长，微波干涉仪的位移测量分辨率仅限于微米级。在本文中，我们提出并演示了一种基于微波干涉测量的新技术，用于具有潜在皮米分辨率的位移测量。在概念验证数值和实验研究中探索了一种基于自制空心同轴电缆的开放式 (OE) 传输线谐振器。该技术涉及两级位移灵敏度放大：一是基于开放端的相位灵敏度放大，二是基于相消干涉的相位灵敏度放大。我们实验证明，通过光谱询问，仅涉及基于开放端的放大，波长灵敏度放大系数为 1800；通过相位询问，相位灵敏度放大系数为 140 万，其中开放端放大和相消干涉放大均参与其中。涉及相移放大，即两级相移放大微波干涉测量(TPAMI)。数值研究和实验结果吻合良好。