“…Figure 3(a) shows the phase distribution in the focal plane, indicating that the topological charge of the resulting vortex beam is 2 1 l . Figure 3(b) shows the intensity distributions of the two symmetrically distributed foci in the X-Z plane.It can be seen from the figure that the [12] actual focal length is 83 . 1 Z μm, which is close to the preset focal length of 2 μm, indicating that the vortex beam is approximately focused at the preset focal point.…”