Theoretical and experimental study of the contribution of radial modes to the pulsed ultrasonic field radiated by a thick piezoelectric disk

1984 ◽  
Vol 75 (6) ◽  
pp. 1722-1731 ◽  
Author(s):  
J. C. Baboux ◽  
F. Lakestani ◽  
M. Perdrix
Keyword(s):  
Experimental Study ◽  
Ultrasonic Field ◽  
Piezoelectric Disk ◽  
Pulsed Ultrasonic

Near-Field Uniform Beams for Pulsed Doppler Ultrasound

1980 ◽  
Vol 2 (4) ◽  
pp. 324-337 ◽  
Author(s):  
Chong-Cheng Fu ◽  
Sharbel E. Noujaim ◽  
Robert S. Jaffe ◽  
Levy Gerzberg ◽  
Roger D. Melen
Keyword(s):  
Flow Measurement ◽  
Pattern Analysis ◽  
Ultrasonic Transducer ◽  
Near Field ◽  
Ultrasonic Field ◽  
Beam Pattern ◽  
Field Approach ◽  
Pulsed Doppler Ultrasound ◽  
Pulsed Ultrasonic

A mathematical model for the beam pattern of a pulsed ultrasonic transducer is introduced. Beam-pattern analysis and simulation of a circular transducer based on this model agree well with the experimental results. It is demonstrated that, in its near field, the pulsed transducer is capable of generating a good approximation to a uniform ultrasonic field which cannot be achieved with a cw transducer. Preliminary error analysis indicates that the near-field beam pattern of the pulsed transducer is suitable for quantitative blood-flow measurement, and design criteria are developed for this application. A prototype has been fabricated and tested in in-vitro experiments, and the results verify the feasibility of the quantitative blood flowmeter principle and the pulsed-transducer near-field approach to the formation of uniform beams.

Time Reversal Focusing Applied to Lithotripsy

1996 ◽  
Vol 18 (2) ◽  
pp. 106-121 ◽  
Author(s):  
Jean-Louis Thomas ◽  
François Wu ◽  
Mathias Fink
Keyword(s):  
Time Reversal ◽  
Surrounding Medium ◽  
Ultrasonic Field ◽  
Ultrasonic Waves ◽  
Least Mean Square ◽  
Transducer Arrays ◽  
Sharp Focusing ◽  
Spatial Coordinates ◽  
Pulsed Ultrasonic ◽  
Focal Zone

Time reversal of ultrasonic field allows a very efficient approach to focusing pulsed ultrasonic waves through lossless inhomogeneous media. Time reversal mirrors (TRM) are made of large transducer arrays, allowing the incident acoustic field to be sampled, time reversed and re-emitted. Time reversal processing permits a choice of any temporal window to be time reversed, allowing operation in an iterative mode. In multitarget media, this process converges on the most reflective target, i.e., the dominant scatterer. In this paper, the time reversal process is applied to track, in real time, a moving gall bladder or kidney stone embedded in its surrounding medium. We investigate the feasibility of a piezoelectric shock wave generator in which the focal zone is moved electronically to track the stone during a lithotripsy treatment. We show that TRM allows us to obtain sharp focusing on one bright point of the stone. The time of flight profile is then determined and used in a least-mean-square method to calculate the spatial coordinates of the stone.

scholarly journals Theoretical and experimental study of the nonlinear ultrasonic field radiated from a conical focused PVDF transducer

2007 ◽  
Vol 56 (10) ◽  
pp. 5909
Author(s):  
Yu Jie ◽  
Zhang Dong ◽  
Liu Xiao-Zhou ◽  
Gong Xiu-Fen ◽  
Song Fu-Xian
Keyword(s):  
Experimental Study ◽  
Ultrasonic Field ◽  
Nonlinear Ultrasonic

Pulsed ultrasonic mixing: An experimental study

2008 ◽  
Vol 86 (5) ◽  
pp. 454-460 ◽  
Author(s):  
R. Vetri Murugan ◽  
R. Nagarajan
Keyword(s):  
Experimental Study ◽  
Pulsed Ultrasonic

Experimental study on the restoration from a tilt-azimuth series for improvement in resolution

1995 ◽  
Vol 53 ◽  
pp. 636-637
Author(s):  
Norio Baba ◽  
Norihiko Ichise ◽  
Syunya Watanabe
Keyword(s):  
Experimental Study ◽  
Spherical Aberration ◽  
Incident Beam ◽  
Optical Parameters ◽  
Beam Tilting ◽  
Illumination Method ◽  
Restoration Method ◽  
Illumination Mode

The tilted beam illumination method is used to improve the resolution comparing with the axial illumination mode. Using this advantage, a restoration method of several tilted beam images covering the full azimuthal range was proposed by Saxton, and experimentally examined. To make this technique more reliable it seems that some practical problems still remain. In this report the restoration was attempted and the problems were considered. In our study, four problems were pointed out for the experiment of the restoration. (1) Accurate beam tilt adjustment to fit the incident beam to the coma-free axis for the symmetrical beam tilting over the full azimuthal range. (2) Accurate measurements of the optical parameters which are necessary to design the restoration filter. Even if the spherical aberration coefficient Cs is known with accuracy and the axial astigmatism is sufficiently compensated, at least the defocus value must be measured. (3) Accurate alignment of the tilt-azimuth series images.

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