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Manipulating acoustic wavefront by inhomogeneous impedance and steerable extraordinary reflection.

Zhao J, Li B, Chen Z, Qiu CW - Sci Rep (2013)

Bottom Line: We unveil the connection between the acoustic impedance along a flat surface and the reflected acoustic wavefront, in order to empower a wide wariety of novel applications in acoustic community.Our designed flat surface can generate double reflections: the ordinary reflection and the extraordinary one whose wavefront is manipulated by the proposed impedance-governed generalized Snell's law of reflection (IGSL).The realization of the complex discontinuity of the impedance surface has been proposed using Helmholtz resonators.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Republic of Singapore [2] Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, Singapore 117546, Republic of Singapore and.

ABSTRACT
We unveil the connection between the acoustic impedance along a flat surface and the reflected acoustic wavefront, in order to empower a wide wariety of novel applications in acoustic community. Our designed flat surface can generate double reflections: the ordinary reflection and the extraordinary one whose wavefront is manipulated by the proposed impedance-governed generalized Snell's law of reflection (IGSL). IGSL is based on Green's function and integral equation, instead of Fermat's principle for optical wavefront manipulation. Remarkably, via the adjustment of the designed specific acoustic impedance, extraordinary reflection can be steered for unprecedented acoustic wavefront while that ordinary reflection can be surprisingly switched on or off. The realization of the complex discontinuity of the impedance surface has been proposed using Helmholtz resonators.

No MeSH data available.


sinθro, re versus sin θi when k0 = 10 rad/m and ψ(y) = −5 y.pro and pre emerge simultaneously in (a). In (b), only pre occurs for the same parameters of (a) except A. The purple dot denotes sin θe in Eq. (6).
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f2: sinθro, re versus sin θi when k0 = 10 rad/m and ψ(y) = −5 y.pro and pre emerge simultaneously in (a). In (b), only pre occurs for the same parameters of (a) except A. The purple dot denotes sin θe in Eq. (6).

Mentions: Fig. 1(d) suggests the possibility of negative reflection for pre, which is further verified for oblique incidence in Fig. 2. In Fig. 2(a), because of the inhomogeneous SAI and the arbitrary A in Eq. (1), both pro and pre occur. Fig. 2(b) depicts the same situation except for pro being switched off as a result of the specifically chosen A according to Eq. (7), while the red line pre stays the same as that in Fig. 2(a). The blue braces represent the region of negative pre. It is noteworthy that pre does not exist if θi is beyond the extreme angle θe = −30° in Eq. (6), corresponding to the purple dots. One field simulation is provided in Supplementary Information.


Manipulating acoustic wavefront by inhomogeneous impedance and steerable extraordinary reflection.

Zhao J, Li B, Chen Z, Qiu CW - Sci Rep (2013)

sinθro, re versus sin θi when k0 = 10 rad/m and ψ(y) = −5 y.pro and pre emerge simultaneously in (a). In (b), only pre occurs for the same parameters of (a) except A. The purple dot denotes sin θe in Eq. (6).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3756330&req=5

f2: sinθro, re versus sin θi when k0 = 10 rad/m and ψ(y) = −5 y.pro and pre emerge simultaneously in (a). In (b), only pre occurs for the same parameters of (a) except A. The purple dot denotes sin θe in Eq. (6).
Mentions: Fig. 1(d) suggests the possibility of negative reflection for pre, which is further verified for oblique incidence in Fig. 2. In Fig. 2(a), because of the inhomogeneous SAI and the arbitrary A in Eq. (1), both pro and pre occur. Fig. 2(b) depicts the same situation except for pro being switched off as a result of the specifically chosen A according to Eq. (7), while the red line pre stays the same as that in Fig. 2(a). The blue braces represent the region of negative pre. It is noteworthy that pre does not exist if θi is beyond the extreme angle θe = −30° in Eq. (6), corresponding to the purple dots. One field simulation is provided in Supplementary Information.

Bottom Line: We unveil the connection between the acoustic impedance along a flat surface and the reflected acoustic wavefront, in order to empower a wide wariety of novel applications in acoustic community.Our designed flat surface can generate double reflections: the ordinary reflection and the extraordinary one whose wavefront is manipulated by the proposed impedance-governed generalized Snell's law of reflection (IGSL).The realization of the complex discontinuity of the impedance surface has been proposed using Helmholtz resonators.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Republic of Singapore [2] Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, Singapore 117546, Republic of Singapore and.

ABSTRACT
We unveil the connection between the acoustic impedance along a flat surface and the reflected acoustic wavefront, in order to empower a wide wariety of novel applications in acoustic community. Our designed flat surface can generate double reflections: the ordinary reflection and the extraordinary one whose wavefront is manipulated by the proposed impedance-governed generalized Snell's law of reflection (IGSL). IGSL is based on Green's function and integral equation, instead of Fermat's principle for optical wavefront manipulation. Remarkably, via the adjustment of the designed specific acoustic impedance, extraordinary reflection can be steered for unprecedented acoustic wavefront while that ordinary reflection can be surprisingly switched on or off. The realization of the complex discontinuity of the impedance surface has been proposed using Helmholtz resonators.

No MeSH data available.