M-Bonacci Zone Plates for Ultrasound Focusing

Abstract

In this work, we present a thorough analysis on M-bonacci zone plates for ultrasound focusing applications. These planar lenses are capable of providing bifocal focusing profiles with equal intensity in both foci and become very appealing for a wide range of scenarios including medical and industrial applications. We show that in high-wavelength domains, such as acoustics or microwaves, the separation between both foci can be finely adjusted at the expense of slightly increasing the distortion of the focusing profile, and we introduce a design parameter to deal with this issue and simplify the design process of these lenses. Experimental measurements are in good agreement with numerical simulations and demonstrate the potential of M-bonacci lenses in ultrasound focusing applications.

Analysis of Predistortion Techniques on Fresnel Zone Plates in Ultrasound Applications

“…In addition, in recent years, a novel kind of lense based on applying a binary sequence to the different Fresnel regions of a conventional FZP [ 20 ] has been presented, increasing the versatility of this kind of devices. If Fibonacci or M-bonacci binary sequences are employed, the resulting lens achieves a bifocal focusing profile [ 21 , 22 , 23 ], while if fractal Cantor binary sequences are used, multifocal focusing profiles with interesting self-similarity properties are achieved [ 24 , 25 , 26 , 27 ]. Analogously, binary Thue–Morse sequences provide focusing profiles with bifocal fractal properties [ 28 , 29 ].…”

Spatio-temporal ultrasound beam modulation to sequentially achieve multiple foci with a single planar monofocal lens

“…Due to their easy design, manufacturing process, and focusing capabilities, this kind of devices are employed in a wide range of fields ranging from optics 15 – 17 to X-ray 18 , 19 , microwaves 20 , 21 , and acoustics 22 – 26 . Moreover, in the past years novel designs based on the FZP structure have been presented, which allow the formation of acoustic vortex 27 , and bifocal 28 , 29 and fractal 30 , 31 intensity distributions, increasing the versatility and interest of this type of lenses.…”

On the Design of Soret Zone Plates Based on Binary Sequences Using Directional Transducers

“…Depending on the nature of this binary mask, different focusing properties are obtained. For instance, using a Fibonacci binary mask results in a bifocal profile with two equal-intensity foci [ 19 , 20 , 21 ], while using fractal Cantor sequences provides a focusing profile with interesting self-similarity multifocal properties [ 22 , 23 , 24 , 25 ]. Thue–Morse binary sequences combine both effects and provide focusing profiles with bifocal fractal properties [ 26 , 27 ].…”