Abstract
Holographic methods from optics can be adapted to acoustics for enabling novel applications in particle manipulation or patterning by generating dynamic custom-tailored acoustic fields. Here, we present three contributions towards making the field of acoustic holography more widespread. Firstly, we introduce an iterative algorithm that accurately calculates the amplitudes and phases of an array of ultrasound emitters in order to create a target amplitude field in mid-air. Secondly, we use the algorithm to analyse the impact of spatial, amplitude and phase emission resolution on the resulting acoustic field, thus providing engineering insights towards array design. For example, we show an onset of diminishing returns for smaller than a quarter-wavelength sized emitters and a phase and amplitude resolution of eight and four divisions per period, respectively. Lastly, we present a hardware platform for the generation of acoustic holograms. The array is integrated in a single board composed of 256 emitters operating at 40 kHz. We hope that the results and procedures described within this paper enable researchers to build their own ultrasonic arrays and explore novel applications of ultrasonic holograms.
Highlights
Optical holographic methods have been adapted to acoustics [13,16,17,18], opening the possibility of generating arbitrary acoustic fields that can be controlled in real time
It is important to note that significant reductions of mean square error (MSE) are obtained, even when emitters get smaller than halfwavelength (4.3 mm), and that no further improvement is obtained below 2 mm (1/4 of the wavelength); this is different from the generation of regular focal points that do not increase its amplitude once the emitters are reduced below half-wavelength size [13]
Acoustic holography has found numerous applications and has advanced rapidly due to the adaptation of methods found in the optics community
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Phased arrays do not have this limitation, since the emission phase and amplitude of each transducer can be controlled by a computer, allowing to change the acoustic field in real time. This capability of phased arrays is encapsulated in commercially available platforms, e.g., Ultraleap, Bristol, UK; Pixie Dust Tech., Tokyo, Japan; SonicEnergy, California, USA, each of which provides technology development and commercialisation towards specific target market solutions. We present SonicSurface, a low-cost open hardware array for generating arbitrary acoustic fields in mid-air. We note the companies commercializing ultrasonic phased arrays offer proprietary solutions that are certified for their use in various commercial applications
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
