Wavefield finite time focusing with reduced spatial exposure

Wavefield finite time focusing with reduced spatial exposure

Meles, G.A. (TU Delft Applied Geophysics and Petrophysics)
van der Neut, J.R. (TU Delft ImPhys/Acoustical Wavefield Imaging)
van Dongen, K.W.A. (TU Delft ImPhys/Acoustical Wavefield Imaging)
Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics; TU Delft ImPhys/Acoustical Wavefield Imaging)

2019

Wavefield focusing is often achieved by time-reversal mirrors, where wavefields emitted by a source located at the focal point are evaluated at a closed boundary and sent back, after time-reversal, into the medium from that boundary. Mathematically, time-reversal mirrors are derived from closed-boundary integral representations of reciprocity theorems. In heterogeneous media, time-reversal focusing theoretically involves in- and output signals that are infinite in time and the resulting waves propagate through the entire medium. Recently, integral representations have been derived for single-sided wavefield focusing. Although the required input signals for this approach are finite in time, the output signals are not and, similar to time-reversal mirroring, the resulting waves propagate through the entire medium. Here, an alternative solution for double-sided wavefield focusing is derived. This solution is based on an integral representation where in- and output signals are finite in time, and where the energy of the waves propagating in the layer embedding the focal point is smaller than with time-reversal focusing. The potential of the proposed method is explored with numerical experiments involving a head model consisting of a skull enclosing a brain.

http://resolver.tudelft.nl/uuid:a06e8d0f-20d8-45ed-8dda-a3aa8512fadf

https://doi.org/10.1121/1.5110716

2019-12-18

0001-4966

The Journal of the Acoustical Society of America, 145 (6), 3521-3530

Accepted Author Manuscript

Institutional Repository

journal article

© 2019 G.A. Meles, J.R. van der Neut, K.W.A. van Dongen, C.P.A. Wapenaar