涡旋光任意入射条件下的旋转物体转速探测(特邀)

Rotational frequency detection of spinning objects at general incidence using vortex beam(Invited)

涡旋光是一种携带轨道角动量的空间结构光束,照射到旋转的平板物体表面时频率会发生移动,这一现象被称为光学旋转多普勒效应,通过测量光束频移可获得平板物体的旋转速率。频移受光束入射条件的影响,通过揭示入射条件影响规律,可实现任意入射条件下的旋转物体转速测量。首先,建立了速度投影模型,分析了光学旋转多普勒效应的产生机理。其次,通过理论推导得出了涡旋光任意入射条件下的旋转多普勒频移分布规律,并提出了提取物体旋转频率的理论方法。最后,搭建了旋转多普勒效应的实验装置,采用拓扑荷数为±18的叠加态拉盖尔-高斯光束在四种不同入射条件下测量旋转多普勒频移谱,将实验频谱与理论频移曲线结合,测得物体的旋转频率,相对误差低于1%。

The vortex beam is a kind of spatially structured optical beam carrying orbital angular momentum,whose frequency shifts when it illuminates the surface of a rotating object.This phenomenon,known as the optical rotational Doppler effect(RDE),can be used to obtain the rotation frequency of a flat object by measuring the frequency shift.While the frequency shift is influenced by the incident condition,by revealing the influencing law of incident condition,the rotational frequency of the object can be measured directly.Firstly,a method of velocity projection was used to analyze the mechanism of optical RDE.Then,the rotational Doppler frequency shift distribution law at general incidence of vortex beam was obtained,and the theoretical method of extracting the rotational frequency was proposed.In the end,an experiment of RDE using a superimposed LaguerreGaussian beam with topological charge l=±18 incident conditions was obtained.The experimental spectrum and the theoretical result were combined,then rotational frequency of the object could be extracted with an error less than 1%.