Plane wave source with minimal harmonic distortion for investigating nonlinear acoustic properties.
The objective of this investigation is to introduce and validate a practical ultrasound source to be used in the investigation of the nonlinear material properties of liquids and soft tissues studied in vitro. Methods based on the progressive distortion of finite amplitude ultrasonic waves in the low megahertz frequency range are most easily implemented under the assumption of plane wave propagation. However, achieving an approximately planar ultrasonic field over substantial propagation distances can be challenging. Furthermore, undesired harmonic distortion of the ultrasonic field prior to insonification of the specified region of interest represents another serious limitation. This paper introduces an approach based on the use of the ultrasonic field emanating from a stainless-steel delay line. Both simulation and direct experimental measurement demonstrate that such a field exhibits relatively planar wave fronts to a good approximation (such that a 3-mm-diam receiver would be exposed to no more than 3 dB of loss across its face) and is free from the significant harmonic distortion that would occur in a conventional water path.
Lloyd
Christopher W
CW
Department of Physics, Washington University in Saint Louis, Saint Louis, Missouri 63130, USA.
Wallace
Kirk D
KD
Holland
Mark R
MR
Miller
James G
JG
D000162:Acoustics / Q000295:instrumentation*; D003198:Computer Simulation; D004867:Equipment Design; D009038:Motion; D017711:Nonlinear Dynamics; D015203:Reproducibility of Results; D013193:Stainless Steel; D013997:Time Factors; D014159:Transducers; D014465:Ultrasonics; D014867:Water
D014867:Water; D013193:Stainless Steel