Compact meta-differentiator for achieving isotropically high-contrast ultrasonic imaging.

Area of Science:

• Biomedical Engineering
• Acoustics
• Metamaterials

Background:

• Ultrasonic imaging offers deep penetration and non-ionizing properties vital for biomedical applications.
• Traditional ultrasonic imaging struggles with low contrast for acoustically transparent targets due to reliance on impedance differences.
• Acoustically transparent targets pose challenges for conventional ultrasonic imaging, limiting diagnostic capabilities.

Purpose of the Study:

• To develop a compact spatial differentiator for isotropic edge-enhanced ultrasonic imaging.
• To improve contrast in imaging acoustically transparent targets without contrast agents or external fields.
• To enable accurate detection of both amplitude and phase objects, including artificial biological models.

Main Methods:

• Design and implementation of a compact spatial differentiator using amplitude and phase meta-gratings.
• Utilizing an amplitude meta-grating for radial linear transmission.
• Employing a phase meta-grating with focus and spiral phases and a first-order topological charge.
• Theoretical analysis, numerical simulations, and experimental validation.

Main Results:

• Demonstrated effective isotropic edge enhancement for amplitude objects.
• Achieved significant contrast improvement without contrast agents or external fields.
• Successfully detected phase objects and artificial biological models with high accuracy.
• Validated the technique through theoretical, numerical, and experimental approaches.

Conclusions:

• The proposed spatial differentiator significantly enhances ultrasonic imaging contrast for challenging targets.
• This technique offers a new approach for medical diagnosis and nondestructive testing.
• The method provides a versatile tool for imaging various object types, including biological models.