Journal ArticleDOI
Sidelobe reduction for limited diffraction pulse-echo systems
Jian-yu Lu,James F. Greenleaf +1 more
TLDR
A summation-subtraction method developed for decreasing the sidelobes is presented and the authors apply this technique to limited diffraction beams and obtain an analytic description.Abstract:
Conventional focused transducers have a sharp focal spot with low sidelobes, but they also have a short depth of field. Commercial medical scanners obtain increased depth of field by combining several images in a montage, each obtained at a different focal depth. Therefore, to get low sidelobes over a large depth of field several transmits must be used, which decrease the frame rate. Limited diffraction beams such as Bessel beams and X waves obtain good resolution over very large depth of field, but they have high sidelobes. A summation-subtraction method developed for decreasing the sidelobes is presented. The method requires three transmits, decreasing the frame rate to one third. The authors apply this technique to limited diffraction beams and obtain an analytic description. >read more
Citations
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Journal ArticleDOI
2D and 3D high frame rate imaging with limited diffraction beams
TL;DR: In this paper, the Fourier method is used to obtain spatial Fourier transform of object functions and images are constructed with an inverse Fourier Transform Transform (TFT) transform.
Journal ArticleDOI
Biomedical ultrasound beam forming
TL;DR: This paper focuses on trade-offs among the above four aspects of beam forming and relate them to system parameters such as aperture size, f-number (the ratio between focal length and aperture diameter), central frequency (wavelength), system bandwidth and sidelobes.
Journal ArticleDOI
Extended high-frame rate imaging method with limited-diffraction beams
Jiqi Cheng,Jian-yu Lu +1 more
TL;DR: The extended theory of high-frame rate imaging theory is extended to include explicitly various transmission schemes such as multiple limited-diffraction array beams and steered plane waves, and shows that image resolution and contrast are increased over a large field of view.
Journal ArticleDOI
Experimental study of high frame rate imaging with limited diffraction beams
TL;DR: The quality (resolution and contrast) of constructed images is virtually identical for both methods, except that the Fourier method is simpler to implement.
Journal ArticleDOI
Two Fundamental Representations of Localized Pulse Solutions to the Scalar Wave Equation
TL;DR: In this paper, two fundamental representations suitable for the derivation of localized pulse (LW) solutions to the scalar wave equation have been studied, one based on superpositions over products of plane waves moving in opposite directions along the characteristic variables z - ct and Z + ct.
References
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Journal ArticleDOI
Diffraction-free beams.
TL;DR: The first experimental investigation of nondiffracting beams, with beam spots as small as a few wavelengths, can exist and propagate in free space, is reported.
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.
Journal ArticleDOI
Realization of general nondiffracting beams with computer-generated holograms
TL;DR: This work shows by the method of stationary phase that any of these wave fields can be realized approximately with a laser and a single computer-generated hologram, and demonstrates experimentally the formation of arbitrary-order Bessel beams and rotationally nonsymmetric beams.
Journal ArticleDOI
Nondiffracting X waves-exact solutions to free-space scalar wave equation and their finite aperture realizations
Jian-yu Lu,James F. Greenleaf +1 more
TL;DR: The authors report families of generalized nondiffracting solutions of the free-space scalar wave equation, and specifically, a subset of these nondiffracted solutions, which are called X waves, which can be almost exactly realized over a finite depth of field with finite apertures and by either broadband or bandlimited radiators.
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Nondiffracting X waves-exact solutions to free-space scalar wave equation and their finite aperture realizations
Jian-yu Lu,James F. Greenleaf +1 more