Discrete multi-step phase hologram for high frequency acoustic modulation

Abstract

Acoustic holograms can recover wavefront stored acoustic field information and produce high-fidelity complex acoustic fields. Benefiting from the advantages of the huge spatial information content unmatched by traditional acoustic components, acoustic holograms pursue the realization of high-resolution complex acoustic fields and gradually tend to high-frequency ultrasound applications. However, conventional continuous phase holograms are limited by 3D printing size and the presence of unavoidable small printing errors make it difficult to achieve acoustic field reconstruction at high frequency accuracy. Here, we present an optimized discrete multi-step phase hologram. It can guarantee the reconstruction quality of image with high robustness, and properly lower the requirement of the 3D printing accuracy. Meanwhile, the concept of reconstruction similarity is proposed to refine a measure of acoustic field quality. In addition, the realized complex acoustic field at 20 MHz promotes the application of acoustic holograms in high frequencies and provides a new way to generate high-fidelity acoustic fields.