Spatial resolution of time-reversal mirrors in two-dimensional and three-dimensional free space environments
Résumé
Time-reversal can be used to locate unknown acoustics sources in a medium at rest or in a flow. This method is based on the time-reversal invariance of the wave propagation equation. A series of time-reversal simulations has been performed with a "mirror" in two-dimensional and three-dimensional free space environments. The waves propagation is simulated by solving the linearized Euler's equations. The results permit to characterize the time-reversal method in terms of spatial resolution and localisation error by analyzing the focal spot width for each simulation. In this paper, mathematical expressions of the time-reversed pressure and approached formulas for the resolution are derived following the diffraction theory and the phase conjugation in two and three-dimensional cases. Numerical and theoretical results are then compared. The focal spot width is then fully determined by two ratios involving three parameters: the array-source distance, the array length and the wavelength.
Domaines
Acoustique [physics.class-ph]Origine | Fichiers éditeurs autorisés sur une archive ouverte |
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