[EN] Vortex beams, characterized by a collimated wavefront with a phase dislocation at their principal axis, have found
practical applications to construct acoustic tweezers for particle
trapping and manipulation, or ...
[EN] Acoustic vortices with subwavelength dimensions and tunable topological charge are theoretically and experimentally synthesized at distances far beyond the Rayleigh diffraction length of the source, using self-demodulation. ...