High-order acoustic Bessel beam generation by spiral gratings

Abstract

We report zero-th and higher order acoustic Bessel beam formation by means of novel passive devices. Using an axisymmetric diffraction grating composed of toroidal rings a zero-th order Bessel beam is generated in transmission. Moreover, focusing of this beam can be achieved by changing the distance between the scatters according to geometrical laws (analogous to the well- known Fresnel zone plates), where acoustic gains up to 34 dB have been observed. On the other hand, scattering by an Archimedean spiral grating is exploited for inverting the phase of the field at each half turn, leading to the creation of a node on-axis. The generated field is a first order Bessel beam which present vorticity. Moreover high-order Bessel beam formation is achieved by incrementing the number of spiral branches, where the number of spiral arms directly correspond to the order of the generated Bessel beam. Focusing of these chiral beam is also possible by using non-uniform Archimedean spirals as the Fermat's spirals. The results obtained allows the control of the vorticity of Bessel-like beams by passive devices, which have potential applications on low-cost acoustic tweezers and acoustic radiation force applications.

@inproceedings{Jimenez2015b,
 author = {Noé Jiménez and Víctor Sánchez-Morcillo and Rubén Picó and Vicent Romero-García and Kestutis Staliunas},
 booktitle = {ICU 2015: International Congress on Ultrasonics. Metz, France. May 11-14},
 doi = {https://doi.org/10.1016/j.phpro.2015.08.146},
 editor = {Physics Procedia},
 month = {5},
 organization = {Georgia Tech Lorraine},
 pages = {245-248},
 publisher = {Elsevier},
 series = {Oral},
 title = {High-order acoustic Bessel beam generation by spiral gratings},
 url = {https://www.sciencedirect.com/science/article/pii/S1875389215008871},
 volume = {70},
 year = {2015}
}