Tarrazó-Serrano, D.; Castiñeira-Ibáñez, S.; Minin, O.V.; Candelas, P.; Rubio, C.; Minin, I.V. Design of Acoustical Bessel-Like Beam Formation by a Pupil Masked Soret Zone Plate Lens. Sensors 2019, 19, 378. https://doi.org/10.3390/s19020378
Tarrazó-Serrano, D.; Castiñeira-Ibáñez, S.; Minin, O.V.; Candelas, P.; Rubio, C.; Minin, I.V. Design of Acoustical Bessel-Like Beam Formation by a Pupil Masked Soret Zone Plate Lens. Sensors 2019, 19, 378. https://doi.org/10.3390/s19020378
Tarrazó-Serrano, D.; Castiñeira-Ibáñez, S.; Minin, O.V.; Candelas, P.; Rubio, C.; Minin, I.V. Design of Acoustical Bessel-Like Beam Formation by a Pupil Masked Soret Zone Plate Lens. Sensors 2019, 19, 378. https://doi.org/10.3390/s19020378
Tarrazó-Serrano, D.; Castiñeira-Ibáñez, S.; Minin, O.V.; Candelas, P.; Rubio, C.; Minin, I.V. Design of Acoustical Bessel-Like Beam Formation by a Pupil Masked Soret Zone Plate Lens. Sensors 2019, 19, 378. https://doi.org/10.3390/s19020378
Abstract
The image performance of acoustic and ultrasound sensors depends on several fundamental parameters such as depth of focus or spatial resolution. There are currently two different type of acoustic diffractive lenses: those which form a diffraction-limited spot with a shallow depth of focus (zone plates) and lenses which form an extended focus (quasi-Bessel beams). In this paper, we investigate a pupil-masked Soret zone plate which allows the tunability of a normalized angular spectrum. It is shown that the depth of focus and the spatial resolution can be modified, without changing the lens structure, by choosing the size of the amplitude pupil mask. This effect is based on the transformation of spherically converging waves into quasi-conical waves, due to the apodization of the central part of the zone plate. The theoretical analysis is verified with both numerical simulations and experimental measurements. A Soret zone plate immersed in water with D/2F=2.5 and F=4.5$\lambda$, changes its depth of focus from 2.84$\lambda$ to 5.9$\lambda$ and the spatial resolution increases from 0.81$\lambda$ to 0.64$\lambda$ at a frequency of 250 kHz, by modifying the pupil mask dimensions of the Soret zone plate.
Keywords
ultrasonic lens; apodization; Soret zone plate
Subject
Physical Sciences, Acoustics
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.