A novel, to the best of our knowledge, tiny velocity measurement system is proposed and demonstrated. This proposed system employs an interference structure in which the reference and measurement paths are filled by two light beams carrying opposite-sign orbital angular momentum (OAM), respectively. The tiny velocity to be measured in the measurement path causes the change of the light path and results in a time-varying phase shift between the reference and measurement paths. This time-varying phase shift leads to the rotation of the petal-like light spot obtained by the interference between two paths. The rotating angular velocity of the petal-like light spot is proportional to the time-varying phase shift caused by the tiny velocity, and it is measured by a chopper and a single-point detector instead of array detectors. This proposed system has a simple structure and achieves a high-accuracy tiny velocity measurement with a measurement error rate that is less than 10 nm/s.

中文翻译：

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使用旋转花瓣状轨道角动量模式进行微小速度测量

据我们所知，提出并演示了一种新颖的微型速度测量系统。该提议的系统采用干涉结构，其中参考和测量路径分别由带有相反符号轨道角动量 (OAM) 的两束光束填充。测量路径中待测的微小速度会引起光路的变化，并导致参考路径和测量路径之间的时变相移。这种随时间变化的相移导致通过两条路径之间的干涉获得的花瓣状光斑的旋转。花瓣状光斑的旋转角速度与微小速度引起的时变相移成正比，用斩波器和单点探测器代替阵列探测器测量。