Steerable High‐Resolution Ultrasound Focusing via Phase‐Array‐Activated Acoustic Meta‐Lenses

Abstract High‐precision dynamic manipulation of 3D acoustic fields is a challenge in acoustics, crucial for applications from high‐resolution imaging to targeted therapy. Conventional phased arrays (PAs), while inherently dynamic, are constrained by the size and number of piezo‐elements, which imposes a trade‐off among imaging resolution, aperture size, and system complexity due to the Nyquist sampling theorem. Acoustic lenses, by contrast, can provide subwavelength resolution but are intrinsically static. To reconcile these problems, here, a proposal is made to employ a steerable‐plane‐wave‐excited meta‐lens (SPWL) to combine plane‐wave steering and wavefront reshaping. In SPWL, an acoustic meta‐lens performs the intricate wavefront engineering, while a sparse PA is employed for flexible plane‐wave steering. The strategy circumvents the Nyquist sampling criterion, thereby mitigating severe spatial aliasing which is typically associated with sparse arrays and enabling a low‐cost system to achieve subwavelength focus scanning across both near and far fields. Its versatility is further demonstrated for spatial scanning of structured acoustic beams, including dual‐spot focusing and vortex. Uniting the high performance, tunability and reduced complexity, the proposed SPWL system paves a transformative route toward advanced ultrasonic devices for biomedical applications.