Circular synthetic aperture acoustic imaging of spherical targets in cylindrical rod clutter

• Published in: The Journal of the Acoustical Society of America Vol. 149; no. 4; p. A141
• Main Authors: LaFrance, Juliana J., Korman, Murray S.
• Format: Journal Article
• Language: English
• Published: 01-04-2021
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/10.0005346

A model apparatus has been built to demonstrate acoustic imaging of several spherical targets in cylindrical clutter. Reflective ultrasonic tomography imaging was chosen because the medical community, using photo-acoustic tomography imaging, utilizes a similar back-projection imaging algorithm. The experiment involves suspending an ultrasonic transducer unit (resonant frequency 1.0 MHz) in an aquarium filled with water. The transducer (sender-receiver) generates a 5-cycle tone burst. The circular plane array transducer diameter is D = 1.27 cm. Its wavelength is 1.48 mm (using c = 1482 m/s). The target, located 15 cm from the source, consists of two 0.64 cm diameter metal spheres separated by 5 cm. A mechanical structure of thin perforated disks (10 cm diam) comprise a step-motor controlled rotational platform that supports the targets and slender stainless steel cylindrical vertical rods (2 mm diameter, 10 cm long) that serve as the clutter. Received echoes versus time (data sets) were measured at 10° rotation increments of the structure (from 0° to 360°) for back-projecting the 2-D image reflectance of the targets among the clutter (using Mathematica®). The original apparatus and supporting electronics were built by Madeline Bell for her USNA Capstone research (Fall 2020) involving scattering from cylindrical targets.