Super-resolution pulse-echo imaging via 3D-printed phase-type acoustic meta-lens

With the rapid development of acoustic imaging and detection technologies, overcoming the intrinsic wave diffraction limit to achieve super-resolution imaging has long been a central goal in acoustics. In this work, we propose a genetic-algorithm-designed meta-lens fabricated via 3D printing that enables subwavelength ultrasound focusing in the far field (>20λ), surpassing the classical 0.5λ resolution limit with the lateral full width at half maximum of 0.42λ while maintaining deep penetration. Quantitative point spread function measurements validate the super-resolution performance and its superiority over the Fresnel lenses is demonstrated. By integrating the phase-modulated metamaterial design with high-precision 3D printing technique, our approach provides a practical and scalable strategy for super-resolution functional devices for biomedical diagnostics and non-destructive testing applications.