An annular array design proposal with multiple geometric pre-foci.

Area of Science:

• Ultrasound transducer technology
• Acoustic imaging systems

Background:

• Standard annular array designs often compromise between aperture size, frequency, and depth of field.
• Optimizing element geometry and pre-focusing is crucial for enhancing ultrasound imaging performance.

Purpose of the Study:

• To introduce and validate a novel annular array design methodology.
• To enable the combination of large aperture, high frequency, and extended receive depth of field in ultrasound arrays.

Main Methods:

• A design method was developed, varying geometric pre-focus across annuli based on maximum allowed phase shift.
• Element dimensions and pre-focus depths were determined to balance performance metrics.
• Receive beam patterns and sidelobe-to-mainlobe energy ratios were simulated for a 7.5-15 MHz array.

Main Results:

• The proposed design method resulted in fewer elements or larger apertures compared to standard equal area designs.
• The designed array (22 mm diameter, 0.23 mm thinnest element) achieved a large aperture and high frequency with an extended depth of field.
• Simulated beams showed sidelobe-to-mainlobe energy ratios within 5 dB of an ideal reference across most of the depth of field.

Conclusions:

• The developed design rules effectively create annular arrays with superior performance characteristics.
• This method allows for significant improvements in ultrasound imaging, particularly in achieving both high resolution and deep penetration.
• The design offers a practical approach to overcoming limitations in conventional ultrasound transducer design.