Figure 5
From: Reflected wavefront manipulation based on ultrathin planar acoustic metasurfaces
Acoustic axicon for the non-diffracting Bessel beam.
(a) Schematic diagram of the design of acoustic axicon. The green cone-like line with base angle 
is the desired equiphase surface for the acoustic axicon so that the phase shift at 
should be proportional to the length of the red line 
. Here, the half-height of the axicon h is selected to be 100 cm. (b) The theoretical continuous phase shift (red dots) and the discrete phase shift provided by the metasurface (blue squares) along the y direction. (c) Spatial distribution of the intensity field 
for the designed axicon with 
. (d) Transverse cross-section of the intensity profile at x = 240 cm from the metasurfaces within the DOF.
