Producing acoustic ‘Frozen Waves’: Simulated experiments with diffraction/attenuation resistant beams in lossy media
| Autor: | Erasmo Recami, Eduardo Tavares Costa, Jose' L. Prego-Borges, Michel Zamboni-Rached |
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| Rok vydání: | 2014 |
| Předmět: |
Diffraction
Acoustics and Ultrasonics Ultrasonic Therapy Transducers FOS: Physical sciences Physics - Classical Physics Absorption symbols.namesake Optics Humans Computer Simulation Envelope (waves) Physics business.industry Attenuation Classical Physics (physics.class-ph) Acoustics Models Theoretical Sound Transducer Attenuation coefficient symbols Ultrasonic sensor Monochromatic color business Algorithms Bessel function |
| Zdroj: | Ultrasonics. 54:1620-1630 |
| ISSN: | 0041-624X |
| DOI: | 10.1016/j.ultras.2014.03.008 |
| Popis: | The so-called Localized Waves (LW), and the "Frozen Waves" (FW), have arisen significant attention in the areas of Optics and Ultrasound, because of their surprising energy localization properties. The LWs resist the effects of diffraction for large distances, and possess an interesting self-reconstruction (self-healing) property, after obstacles with size smaller than the antenna's; while the FWs, a sub-class of theirs, offer the possibility of arbitrarily modeling the field longitudinal intensity pattern inside a prefixed interval, for instance 0 < z < L, of the wave propagation axis. More specifically, the FWs are localized fields "at rest", that is, with a static envelope (within which only the carrier wave propagates), and can be endowed moreover with a high transverse localization. In this paper we investigate by simulated experiments, various cases of generation of ultrasonic FW fields, with frequency f_o = 1 MHz in a water-like medium, taking account of the effects of attenuation. We present results of FWs for distances up to L=80 mm, in attenuating media with absorption coefficients alpha in the range 70 < alpha < 170 dB/m. Such simulated FW fields are constructed by using a procedure developed by us, via appropriate finite superpositions of monochromatic ultrasonic Bessel beams. We pay due attention to the selection of the FW parameters, constrained by the tight restrictions imposed by experimental Acoustics, and to some practical implications of the transducer design. The energy localization properties of the Frozen Waves can find application even in many medical apparatus, such as bistouries or acoustic tweezers, and for treatment of diseased tissues (in particular, for the destruction of tumor cells, without affecting the surrounding tissues; besides for a safe kidney stone shuttering, etcetera). 13 two-column pages, with 16 Figures, and 4 Tables. [Keywords: "Frozen Waves", Ultrasound, Diffraction, Attenuation, Bessel beam superpositions, Annular transducers.] |
| Databáze: | OpenAIRE |
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