Breaking the acoustic diffraction limit with an arbitrary shape acoustic magnifying lens

Area of Science:

• Acoustics
• Metamaterials
• Wave Optics

Background:

• Conventional acoustic lenses face limitations in resolution and source positioning.
• Breaking the diffraction limit is a long-standing challenge in wave manipulation.

Purpose of the Study:

• To propose a design principle for an arbitrary shape magnifying lens (ASML) based on transformation acoustics.
• To achieve far-field high-resolution imaging independent of source position.

Main Methods:

• Theoretical investigation using transformation acoustics methodology.
• Design and implementation of an acoustic null medium (ANM).
• Fabrication of the ASML using acoustic unit cells and effective medium theory.

Main Results:

• The proposed ASML breaks the diffraction limit, enabling high-resolution far-field imaging.
• An acoustic null medium (ANM) was identified as a suitable homogeneous and topology-independent material.
• Experimental results validated the theoretical design principle for the implemented ASML.

Conclusions:

• The developed ASML offers a novel approach to sub-diffraction imaging.
• The acoustic null medium provides a practical and versatile platform for acoustic devices.
• Potential applications include advanced medical imaging, biomedical sensing, and focused ultrasound surgery.