Producing Bessel Beams With an RF Transformer.

Area of Science:

• Acoustics and Wave Phenomena
• Medical Imaging Technology
• Materials Science

Background:

• Bessel beams offer diffraction-free propagation and large depth of field, ideal for various applications.
• Traditional ultrasound Bessel beam generation requires bulky, power-intensive multi-amplifier systems, limiting wearable applications.

Purpose of the Study:

• To develop a compact and power-efficient method for generating broadband Bessel beams for ultrasound applications.
• To enable Bessel beam applications in wearable medical imaging and super-resolution imaging.

Main Methods:

• Utilized a single high-voltage radio-frequency (RF) power amplifier and a custom RF transformer.
• Employed a custom 10-ring, 2.5-MHz broadband annular array transducer made of PZT ceramic/polymer composite.
• Generated pulse Bessel beams in water at approximately +/-90 V.

Main Results:

• Achieved pulse Bessel beams comparable to those from multiple amplifiers, simulations, and theory.
• Demonstrated a -6 dB beamwidth of approximately 2.53 mm (4.22 wavelengths).
• Obtained a significant depth of field of approximately 216 mm (360 wavelengths).

Conclusions:

• The new method significantly reduces the size, weight, and power consumption of Bessel beam generation systems.
• This advancement facilitates the integration of Bessel beams into wearable ultrasound devices.
• Demonstrated potential for 3D and multi-plane imaging using Bessel beams with a scanned reflector.