Bidirectional Lambertian Scatterers Using Acoustic Holograms for the Simultaneous Control of Reflected and Transmitted Wavefronts

Abstract Acoustic holography enables the creation of tailored spatiotemporal wavefield distributions. In this study, the design of acoustic holograms that simultaneously control both the reflected and the transmitted fields are presented. This is accomplished through the use of a bidirectional metasurface, which encodes the phase of a desired wavefront in a discrete spatial distribution of monolithic sub‐elements. This approach is employed in particular to design an optimized hologram that behaves as an ideal Lambertian scatter for both reflection and transmission. The design follows a quadratic‐residue sequence, with theoretical results validated both numerically and experimentally. It is observed that this kind of structure produces a uniform scattering response, with a high diffusion coefficient of approximately 0.7 and a correlation scattering coefficient of 0.98 in both transmission and reflection. The hologram demonstrates the potential to significantly reduce imaging artefacts in ultrafast ultrasound techniques in strongly reverberating environments, as evidenced by examples.