Zhong Yiming, Zhang Yi, Zhang Xiangdong, Sun Houjun, Zhao Guoqiang
Opt Express. 2021 Aug 2;29(16):26210-26219. doi: 10.1364/OE.432044.
The rotational Doppler effect caused by vortex beam carrying orbital angular momentum is recently used to estimate the rotational velocity of the object. However, the vortex beam only has the spiral phase distribution in one dimension, which means that only the rotational movement of the object would introduce the frequency shift. Also, the vortex beam has a spatial amplitude distribution of doughnut-shaped, which is not suitable for many application scenarios. To simultaneously measure the velocity of an arbitrary three-dimensional moving object, we propose theoretically and demonstrate experimentally an effective method by constructing a novel modulated field. Different from the plane wave and the vortex beam, the modulated field has linear phase distribution in azimuth and elevation directions. In addition, the modulated field has the maximal radiation intensity in the center, which avoids the beam divergence of the vortex beam. By decomposing the frequency shift caused by the radial, azimuth and elevation movements, we realize the velocity measurement in three dimensions. Experiments in a microwave system show that the estimated velocity errors are lower than 6.0%.
最近，携带轨道角动量的涡旋光束所引起的旋转多普勒效应被用于估计物体的旋转速度。然而，涡旋光束仅在一维上具有螺旋相位分布，这意味着只有物体的旋转运动会引入频移。此外，涡旋光束具有甜甜圈形状的空间幅度分布，这不适用于许多应用场景。为了同时测量任意三维运动物体的速度，我们从理论上提出并通过构建一种新型调制场进行了实验验证。与平面波和涡旋光束不同，调制场在方位角和仰角方向上具有线性相位分布。此外，调制场在中心具有最大辐射强度，这避免了涡旋光束的光束发散。通过分解由径向、方位角和仰角运动引起的频移，我们实现了三维速度测量。在微波系统中的实验表明，估计的速度误差低于6.0%。
