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Three-dimensional collimated self-accelerating beam through acoustic metascreen.

Li Y, Assouar MB - Sci Rep (2015)

Bottom Line: Acoustic metascreen with deep subwavelength spatial resolution, composed of hybrid structures combining four Helmholtz resonators and a straight pipe, transmitting sound efficiently and shifting fully the local phase is evidenced.With an extra phase profile provided by the metascreen, the transmitted sound can be tuned to propagate along arbitrary caustic curvatures to form a focused spot.Due to the caustic nature, the formed beam possesses the capacities of bypassing obstacles and holding the self-healing feature, paving then a new way for wave manipulations and indicating various potential applications, especially in the fields of ultrasonic imaging, diagnosis and treatment.

View Article: PubMed Central - PubMed

Affiliation: CNRS, Institut Jean Lamour, Vandoeuvre-lès-Nancy F-54500, France.

ABSTRACT
We report the generation of three-dimensional acoustic collimated self-accelerating beam in non-paraxial region with sourceless metascreen. Acoustic metascreen with deep subwavelength spatial resolution, composed of hybrid structures combining four Helmholtz resonators and a straight pipe, transmitting sound efficiently and shifting fully the local phase is evidenced. With an extra phase profile provided by the metascreen, the transmitted sound can be tuned to propagate along arbitrary caustic curvatures to form a focused spot. Due to the caustic nature, the formed beam possesses the capacities of bypassing obstacles and holding the self-healing feature, paving then a new way for wave manipulations and indicating various potential applications, especially in the fields of ultrasonic imaging, diagnosis and treatment.

No MeSH data available.


Related in: MedlinePlus

Collimated self-bending beam from a normally incident plan wave.(a) The formed collimated self-bending beam with the desired phase shift profile with λ = 0.2 m. (b) The sound field of the metascreen constructed by 100 elements, where the field at z > 0 is sound pressure level (SPL, normalized by the maximum value) and at x < 0 is a snapshot of normalized sound pressure. The metascreen yields a phase profile ϕ(r) on the normally incident plane waves propagating along +x direction. (c) Sound field same to (b) while with a spherical obstacle centered (r, z) = (0, rb/2) (yellow region, diameter ds = 3λ) in front of the metascreen. (d) Sound field same to (c) while with an additional ring-like obstacle centered (r, z) = (rb/2, rb/2) (yellow region, cross-sectional diameter dr = λ) located along the trajectory. (e) Comparison of the SPL along the axis in (a–d). The SPL is normalized to the maximum value along the z axis. A focused spot could be observed near z = 6.3λ. The large deviation of the SPL around z = 0.5 m convincingly stems from the existing spherical obstacle.
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f3: Collimated self-bending beam from a normally incident plan wave.(a) The formed collimated self-bending beam with the desired phase shift profile with λ = 0.2 m. (b) The sound field of the metascreen constructed by 100 elements, where the field at z > 0 is sound pressure level (SPL, normalized by the maximum value) and at x < 0 is a snapshot of normalized sound pressure. The metascreen yields a phase profile ϕ(r) on the normally incident plane waves propagating along +x direction. (c) Sound field same to (b) while with a spherical obstacle centered (r, z) = (0, rb/2) (yellow region, diameter ds = 3λ) in front of the metascreen. (d) Sound field same to (c) while with an additional ring-like obstacle centered (r, z) = (rb/2, rb/2) (yellow region, cross-sectional diameter dr = λ) located along the trajectory. (e) Comparison of the SPL along the axis in (a–d). The SPL is normalized to the maximum value along the z axis. A focused spot could be observed near z = 6.3λ. The large deviation of the SPL around z = 0.5 m convincingly stems from the existing spherical obstacle.

Mentions: The realization of our screen allows effective control of sound propagation along desired trajectory. The desired collimated self-bending beam is shown in Fig. 3(a). A boundary with a unity amplitude and a continuous phase profile is employed to form the self-bending beam. We construct the metascreen with 100 elements along r direction with desired geometrical parameters, w1/w and sn/w, shown in Fig. 2(b,c). The transmitted wave fields through the metascreen is shown in Fig. 3(b) with a normally plane incident wave propagating along +z direction. The screen yields a discrete desired phase shift profile on the incident wave with spatial resolution w = λ/10. The self-bending beam is well established [cf. Fig. 3(b)] and in a good shape of the desired propagating trajectory and then focused at the spot. Excellent agreement could be obtained by comparing the wave fields in Fig. 3(a,b). The excellent performance of the proposed metascreen owes to the fine spatial resolution, the high transmission and the fully controlled phase shift.


Three-dimensional collimated self-accelerating beam through acoustic metascreen.

Li Y, Assouar MB - Sci Rep (2015)

Collimated self-bending beam from a normally incident plan wave.(a) The formed collimated self-bending beam with the desired phase shift profile with λ = 0.2 m. (b) The sound field of the metascreen constructed by 100 elements, where the field at z > 0 is sound pressure level (SPL, normalized by the maximum value) and at x < 0 is a snapshot of normalized sound pressure. The metascreen yields a phase profile ϕ(r) on the normally incident plane waves propagating along +x direction. (c) Sound field same to (b) while with a spherical obstacle centered (r, z) = (0, rb/2) (yellow region, diameter ds = 3λ) in front of the metascreen. (d) Sound field same to (c) while with an additional ring-like obstacle centered (r, z) = (rb/2, rb/2) (yellow region, cross-sectional diameter dr = λ) located along the trajectory. (e) Comparison of the SPL along the axis in (a–d). The SPL is normalized to the maximum value along the z axis. A focused spot could be observed near z = 6.3λ. The large deviation of the SPL around z = 0.5 m convincingly stems from the existing spherical obstacle.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4664955&req=5

f3: Collimated self-bending beam from a normally incident plan wave.(a) The formed collimated self-bending beam with the desired phase shift profile with λ = 0.2 m. (b) The sound field of the metascreen constructed by 100 elements, where the field at z > 0 is sound pressure level (SPL, normalized by the maximum value) and at x < 0 is a snapshot of normalized sound pressure. The metascreen yields a phase profile ϕ(r) on the normally incident plane waves propagating along +x direction. (c) Sound field same to (b) while with a spherical obstacle centered (r, z) = (0, rb/2) (yellow region, diameter ds = 3λ) in front of the metascreen. (d) Sound field same to (c) while with an additional ring-like obstacle centered (r, z) = (rb/2, rb/2) (yellow region, cross-sectional diameter dr = λ) located along the trajectory. (e) Comparison of the SPL along the axis in (a–d). The SPL is normalized to the maximum value along the z axis. A focused spot could be observed near z = 6.3λ. The large deviation of the SPL around z = 0.5 m convincingly stems from the existing spherical obstacle.
Mentions: The realization of our screen allows effective control of sound propagation along desired trajectory. The desired collimated self-bending beam is shown in Fig. 3(a). A boundary with a unity amplitude and a continuous phase profile is employed to form the self-bending beam. We construct the metascreen with 100 elements along r direction with desired geometrical parameters, w1/w and sn/w, shown in Fig. 2(b,c). The transmitted wave fields through the metascreen is shown in Fig. 3(b) with a normally plane incident wave propagating along +z direction. The screen yields a discrete desired phase shift profile on the incident wave with spatial resolution w = λ/10. The self-bending beam is well established [cf. Fig. 3(b)] and in a good shape of the desired propagating trajectory and then focused at the spot. Excellent agreement could be obtained by comparing the wave fields in Fig. 3(a,b). The excellent performance of the proposed metascreen owes to the fine spatial resolution, the high transmission and the fully controlled phase shift.

Bottom Line: Acoustic metascreen with deep subwavelength spatial resolution, composed of hybrid structures combining four Helmholtz resonators and a straight pipe, transmitting sound efficiently and shifting fully the local phase is evidenced.With an extra phase profile provided by the metascreen, the transmitted sound can be tuned to propagate along arbitrary caustic curvatures to form a focused spot.Due to the caustic nature, the formed beam possesses the capacities of bypassing obstacles and holding the self-healing feature, paving then a new way for wave manipulations and indicating various potential applications, especially in the fields of ultrasonic imaging, diagnosis and treatment.

View Article: PubMed Central - PubMed

Affiliation: CNRS, Institut Jean Lamour, Vandoeuvre-lès-Nancy F-54500, France.

ABSTRACT
We report the generation of three-dimensional acoustic collimated self-accelerating beam in non-paraxial region with sourceless metascreen. Acoustic metascreen with deep subwavelength spatial resolution, composed of hybrid structures combining four Helmholtz resonators and a straight pipe, transmitting sound efficiently and shifting fully the local phase is evidenced. With an extra phase profile provided by the metascreen, the transmitted sound can be tuned to propagate along arbitrary caustic curvatures to form a focused spot. Due to the caustic nature, the formed beam possesses the capacities of bypassing obstacles and holding the self-healing feature, paving then a new way for wave manipulations and indicating various potential applications, especially in the fields of ultrasonic imaging, diagnosis and treatment.

No MeSH data available.


Related in: MedlinePlus