Figure 4
From: Acoustic Holographic Rendering with Two-dimensional Metamaterial-based Passive Phased Array

Experimental results of the holographic lensing of three circular spots of different diameters.
(a) Illustration of the multiple focus lensing with the holographic lens. The isosurface of power and the projected power pattern on the focal plane (300 mm) is calculated with FEM-based full wave simulation. The three dashed circles with different radii are the designed focal spots. (b) The simulated and measured power distribution patterns at the depth of 300 mm.