Bridging the numerical-physical gap in acoustic holography via end-to-end differentiable structural optimization

TL;DR

This paper introduces a physics-aware differentiable optimization framework for acoustic holography, enabling high-fidelity wavefront shaping by directly incorporating 3D lens geometries into the design process, surpassing traditional phase-only methods.

Contribution

It presents a novel differentiable relaxation called DHLA that integrates physical lens structures into the optimization, improving the accuracy and applicability of acoustic holograms.

Findings

TOAHs outperform POAHs in field reconstruction fidelity.

The framework enables precise neuromodulation in a mouse model.

Reconciles numerical design with physical realization for complex environments.

Abstract

Acoustic holography provides a practical means of flexibly controlling acoustic wavefronts. However, high-fidelity shaping of acoustic fields remains constrained by the numerical-physical gap inherent in conventional phase-only designs. These approaches realize a two-dimensional phase-delay profile as a three-dimensional thickness-varying lens, while neglecting wave-matter interactions arising from the lens structure. Here, we introduce an end-to-end, physics-aware differentiable structural optimization framework that directly incorporates three-dimensional lens geometries into the acoustic simulation and optimization loop. Using a novel differentiable relaxation, termed Differentiable Hologram Lens Approximation (DHLA), the lens geometry is treated as a differentiable design variable, ensuring intrinsic consistency between numerical design and physical realization. The resulting Thickness-Only Acoustic Holograms (TOAHs) significantly outperform state-of-the-art phase-only acoustic holograms (POAHs) in field reconstruction fidelity and precision under complex conditions. We further demonstrate the application of the framework to spatially selective neuromodulation in a neuropathic pain mouse model, highlighting its potential for non-invasive transcranial neuromodulation. In summary, by reconciling numerical design with physical realization, this work establishes a robust strategy for high-fidelity acoustic wavefront shaping in complex environments.