The effect of Dirac phase on acoustic vortex in media with screw dislocation

Torabi, Reza; Rezaei, Zahra

doi:10.1016/j.physleta.2013.05.014

Cited by 4 publications

(4 citation statements)

References 43 publications

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“…They have been demonstrated across a broad range of the electromagnetic spectrum [22][23][24][25]. Acoustic vortex beams have been studied by a number of groups [26,27], while optical vortex beams are finding further application beyond typical optics studies in astrophysics [28], and in telecommunications [20,29,30].…”

Section: Introductionmentioning

confidence: 99%

Shaping electron beams for the generation of innovative measurements in the (S)TEM

Verbeeck

Guzzinati

Clark

et al. 2014

Comptes Rendus. Physique

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In TEM, a typical goal consists of making a small electron probe in the sample plane in order to obtain high spatial resolution in scanning transmission electron microscopy. In order to do so, the phase of the electron wave is corrected to resemble a spherical wave compensating for aberrations in the magnetic lenses. In this contribution we discuss the advantage of changing the phase of an electron wave in a specific way in order to obtain fundamentally different electron probes opening up new application in the (S)TEM. We focus on electron vortex states as a specific family of waves with an azimuthal phase signature and discuss their properties, production and applications. The concepts presented here are rather general and also different classes of probes can be obtained in a similar fashion showing that electron probes can be tuned to optimise a specific measurement or interaction.

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Section: Introductionmentioning

confidence: 99%

Shaping electron beams for the generation of innovative measurements in the (S)TEM

Verbeeck

Guzzinati

Clark

et al. 2014

Comptes Rendus. Physique

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“…As a kind of acoustic wave with continuous helical wave fronts around the beam axis, the acoustic vortex (AV) [6][7][8] shows an obvious pressure zero at the vortex center with an intrinsic phase singularity. The possibility of the OAM transfer to objects is produced by the continuous phase spiral.…”

Section: Introductionmentioning

confidence: 99%

Random phase screen influence of the inhomogeneous tissue layer on the generation of acoustic vortices

Dong

et al. 2018

Chinese Phys. B

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The influence of the inhomogeneous tissue layer on the generation of acoustic vortices (AV) is studied theoretically and experimentally based on the phase screen model. By considering the time-shift of a random phase screen, the formula of acoustic pressure for the AV beam generated by a circular array of eight planar piston sources is derived. With the actual correlation length of the abdominal wall, numerical simulations before and after the insertion of the inhomogeneous tissue layer are conducted, and also demonstrated by experimental measurements. It is proved that, when the thickness variation of the phase screen is less than one wavelength, no significant influence on the generation of AVs can be produced. The variations of vortex nodes and antinodes in terms of the location, shape, and size of AVs are not obvious. Although the circular pressure distribution might be deformed by the phase interference with a larger thickness variation, AVs can still be generated around the center axis with perfect phase spirals in a reduced effective radius. The favorable results provide the feasibility of AV generation inside the human body and suggest the application potential of AVs in object manipulation for biomedical engineering.

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“…Being eigenstates of the OAM operator they posses a well defined OAM of m per particle. Preceded by the early theoretical work of Nye and Berry [1] and Allen et al [2], numerous ways of creating OAM eigenstates have been designed in optics [3,4] and electron microscopy [5][6][7][8][9], acoustics [10,11], and neutronics [12] In optics, these so-called vortex beams have found their way into a vast number of applications ranging from optical tweezers and nanomanipulation [13][14][15][16] and astrophysics [17][18][19] to telecommunication [20,21]. Also, in electron microscopy, theoretical research and early experiments look very promising for vortex beams as a tool to manipulate nanocrystals [22] and investigate chiral crystals [23].…”

Section: Introductionmentioning

confidence: 99%

Local orbital angular momentum revealed by spiral-phase-plate imaging in transmission-electron microscopy

Juchtmans

Verbeeck

2016

Phys. Rev. A

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The orbital angular momentum (OAM) of light and matter waves is a parameter that has been getting increasingly more attention over the past couple of years. Beams with a well-defined OAM, the so-called vortex beams, are applied already in, e.g., telecommunication, astrophysics, nanomanipulation and chiral measurements in optics and electron microscopy. Also, the OAM of a wave induced by the interaction with a sample, has attracted a lot of interest. In all these experiments it is crucial to measure the exact (local) OAM content of the wave, whether it is an incoming vortex beam or an exit wave after interacting with a sample. In this work we investigate the use of spiral phase plates (SPPs) as an alternative to the programmable phase plates used in optics to measure OAM. We derive analytically how these can be used to study the local OAM components of any wave function. By means of numerical simulations we illustrate how the OAM of a pure vortex beam can be measured. We also look at a sum of misaligned vortex beams and show, by using SPPs, the position and the OAM of each individual beam can be detected. Finally, we look at the OAM induced by a magnetic dipole on a free-electron wave and show how the SPP can be used to localize the magnetic poles and measure their "magnetic charge." Although our findings can be applied to study the OAM of any wave function, they are of particular interest for electron microscopy where versatile programmable phase plates do not yet exist.

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The effect of Dirac phase on acoustic vortex in media with screw dislocation

Cited by 4 publications

References 43 publications

Shaping electron beams for the generation of innovative measurements in the (S)TEM

Shaping electron beams for the generation of innovative measurements in the (S)TEM

Random phase screen influence of the inhomogeneous tissue layer on the generation of acoustic vortices

Local orbital angular momentum revealed by spiral-phase-plate imaging in transmission-electron microscopy

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