Journal ArticleDOI
Low sidelobe limited diffraction beams in the nonlinear regime.
Sverre Holm,Fabrice Prieur +1 more
TLDR
Simulations presented here show that for breast tissue, which only has about 10% of the absorption of previous criteria, one will still get sidelobes which are comparable to that of a rectangular aperture even when the sidelOBes would be high in a non-absorbing medium.Abstract:
In linear propagation, sidelobe levels of Bessel limited diffraction beams are only about 8 dB down relative to the mainlobe. In the nonlinear regime, these beams will have a region near the source where the side-lobe level of the second harmonic is 16 dB down, but this region has usually been considered to be so small that it is of little practical interest. In this paper it is shown that when there are only 1 to 3 sidelobes in a finite aperture Bessel beam, the second harmonic field will have low sidelobes for distances up to half of the depth of field. This result is backed up by simulations. In a medium with absorption, previous theory has shown that the sidelobes of the Bessel beam will also be reduced but only for absorption that was too high to be of practical use. Simulations presented here show that for breast tissue, which only has about 10% of the absorption of previous criteria, one will still get sidelobes which are comparable to that of a rectangular aperture even when the sidelobes would be high in a non-absorbing medium.read more
Citations
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Journal ArticleDOI
Feasibility of Second Harmonic Imaging in Active Sonar: Measurements and Simulations
TL;DR: In this paper, the authors investigated the feasibility of utilizing the part of the signal generated around the second harmonic frequency band by nonlinear propagation of sound in water and presented the potential enhancements the second-harmonic signal may provide for target imaging as well as multifrequency target recognition.
Second—Harmonic Generation of Bessel Beams in Lossy Media
TL;DR: In this article, the second-harmonic generation of Bessel beams in lossy media is analyzed and the effect of absorption on the radial pattern of the second harmonic beam is investigated.
References
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Journal ArticleDOI
Exact solutions for nondiffracting beams. I. The scalar theory
TL;DR: In this paper, exact nonsingular solutions of the scalar-wave equation for beams that are non-diffracting were presented, which means that the intensity pattern in a transverse plane is unaltered by propagating in free space.
Book
Diagnostic Ultrasound Imaging: Inside Out
TL;DR: Diagnostic Ultrasound Imaging provides a unified description of the physical principles of ultrasound imaging, signal processing, systems and measurements that enable practicing engineers, students and clinical professionals to understand the essential physics and signal processing techniques behind modern imaging systems.
Journal ArticleDOI
Distortion and harmonic generation in the nearfield of a finite amplitude sound beam
TL;DR: In this article, the distortion and harmonic generation in the near field of a finite amplitude sound beam are considered, assuming time-periodic but otherwise arbitrary on-source conditions, and the amplitude and phase of the fundamental and first few harmonics are calculated along the beam axis, and across the beam at various ranges from the source.
Journal ArticleDOI
Ultrasonic nondiffracting transducer for medical imaging
Jian-yu Lu,J.F. Greenleaf +1 more
TL;DR: The nondiffracting J/sub 0/ Bessel beam is evaluated, and its application to medical imaging is suggested and computer simulations and experimental results for a ten-ring annular Bessel shaded transducer are described.