From the time-reversal mirror to the instantaneous time mirror

Fink, Mathias; Fort, Emmanuel

doi:10.1140/epjst/e2016-60258-8

Cited by 12 publications

(4 citation statements)

References 21 publications

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“…Temporal changes of material parameters have an effect on wave propagation and scattering, comparable with, but not identical to, the effect of spatial changes. Since the initial work on wave propagation and scattering in time-dependent materials (Morgenthaler 1958;Jiang 1975), the research in this field has recently got significant momentum (Bacot et al 2016;Fink & Fort 2017;Koutserimpas & Fleury 2018;Bal et al 2019;Peng et al 2020;Caloz & Deck-Léger 2020a;Mounaix et al 2020;Ramaccia et al 2020;Garnier 2021;Apffel & Fort 2022;Moussa et al 2023;Hidalgo-Caballero et al 2023;Ptitcyn et al 2023). Various authors discuss the analogy between the wave equations for time-dependent and space-dependent materials (Mendonça & Shukla 2002;Xiao et al 2014;de Hoop & Lager 2014;Salem & Caloz 2015;Torrent et al 2018;Caloz & Deck-Léger 2020b;Van Manen et al 2024).…”

Section: Introductionmentioning

confidence: 99%

Wave-field representations with Green's functions, propagator matrices, and Marchenko-type focusing functions

Wapenaar

2022

The Journal of the Acoustical Society of America

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Classical acoustic wave-field representations consist of volume and boundary integrals, of which the integrands contain specific combinations of Green's functions, source distributions, and wave fields. Using a unified matrix-vector wave equation for different wave phenomena, these representations can be reformulated in terms of Green's matrices, source vectors, and wave-field vectors. The matrix-vector formalism also allows the formulation of representations in which propagator matrices replace the Green's matrices. These propagator matrices, in turn, can be expressed in terms of Marchenko-type focusing functions. An advantage of the representations with propagator matrices and focusing functions is that the boundary integrals in these representations are limited to a single open boundary. This makes these representations a suitable basis for developing advanced inverse scattering, imaging and monitoring methods for wave fields acquired on a single boundary.

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Section: Introductionmentioning

confidence: 99%

Wave-field representations with Green's functions, propagator matrices, and Marchenko-type focusing functions

Wapenaar

2022

The Journal of the Acoustical Society of America

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“…While radiation from a point source is characterized by a diverging forward propagation, the wave equation also admits a backward counterpart that can converge to the source location. This behavior has been found to be reproducible through the time reversal mirror (TRM) and the instantaneous time mirror (ITM) which have recently been the subject of extensive numerical and practical experimentation [1]- [8].…”

Section: Introductionmentioning

confidence: 87%

Tailoring Instantaneous Time Mirrors for Time Reversal Focusing in Absorbing Media

T.¹,

Nobre²,

Fort³

et al. 2021

Preprint

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The time reversal symmetry of the wave equation allows wave refocusing back at the source. However, this symmetry does not hold in lossy media. We present a new strategy to compensate wave amplitude losses due to attenuation. The strategy leverages the instantaneous time mirror (ITM) which generates reversed waves by a sudden disruption of the medium properties. We create a heterogeneous ITM whose disruption is unequal throughout the space to create waves of different amplitude. The time-reversed waves can then cope with different attenuation paths as typically seen in heterogeneous and lossy environments. We consider an environment with biological tissues and apply the strategy to a two-dimensional digital human phantom from the abdomen. A stronger disruption is introduced where forward waves suffer a history of higher attenuation, with a weaker disruption elsewhere. Computer simulations show heterogeneous ITM is a promising technique to improve time reversal refocusing in heterogeneous, lossy, and dispersive spaces.

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“…In theory, ITM and TRM work under the same principle but exploit different possibilities of the Cauchy initial or boundary conditions, respectively [4,10]. Our interest here lies in the quality of the reversed foci generated by their use.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Reversed Propagations Generated Using Time Reversal Mirrors and Instantaneous Time Mirrors in Electromagnetics

2021

RSL

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The possibility of Instantaneous Time Mirror is explored in electromagnetic waves through the manipulation of a medium's complex relative permittivity, causing a sudden disruption to the waves' speed. The quality of the reversed foci obtained through Instantaneous Time Mirror and its classical alternative, Time Reversal Mirror, is reported in both air and water. We show how careful setup of both techniques can produce similar results. We adopt a visually-guided qualitative metric, but also quantitative metrics to describe accuracy and resolution, including a newly-proposed method to assess the multi-dimensional resolution of a focus.

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From the time-reversal mirror to the instantaneous time mirror

Cited by 12 publications

References 21 publications

Wave-field representations with Green's functions, propagator matrices, and Marchenko-type focusing functions

Wave-field representations with Green's functions, propagator matrices, and Marchenko-type focusing functions

Tailoring Instantaneous Time Mirrors for Time Reversal Focusing in Absorbing Media

Characteristics of Reversed Propagations Generated Using Time Reversal Mirrors and Instantaneous Time Mirrors in Electromagnetics

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