Acoustic Holography in the Megahertz Frequency Range with Optimal Lens Topologies and Nonlinear Acoustic Feedback

TL;DR

This paper introduces a novel optimization framework for designing high-fidelity acoustic holograms in the megahertz range, enabling advanced applications like neuro-interventions and hydrocephalus monitoring.

Contribution

It develops a heterogeneous angular spectrum approach that incorporates variable speed-of-sound maps and wavefront aberrations for optimized lens topologies in acoustic holography.

Findings

Supports high-precision neuro-interventions

Enables skull-compensating lens alignment

Monitors CSF fluid in hydrocephalus

Abstract

Acoustic holography in the megahertz frequency range can impact numerous applications, including manufacturing, non-destructive testing, and transcranial ultrasound. However, designing lens topologies for complex acoustic holograms in the megahertz range poses a significant challenge, as weave propagation effects through the lens cannot be ignored. Here, we show that the inherent ability of heterogeneous angular spectrum approach to incorporate in plane varying speed-of-sound maps and support rapid differentiable optimization of lens thickness profiles can generate lens topologies for high fidelity acoustic holography. Crucially, we show that this framework can also account for wavefront aberrations in the propagation media, providing the opportunity to reconfigure this disruptive technology for high precision neuro-interventions. Our investigations also revealed that low frequency acoustic feedback generated by nonlinear mixing of high frequency waves allows attaining accurate skull-compensating lens alignment and creates the possibility to monitor CSF fluid build-up and removal in hydrocephalus. Together, our findings support the design of simple, economical, and high-performance ultrasound systems.