Experimental analysis of acoustical properties of irregular cavities using laser refracto-vibrometry

Mbailassem, Fulbert; Leclère, Quentin; Redon, Emmanuel; Gourdon, Emmanuel

doi:10.1016/j.apacoust.2017.09.017

Cited by 6 publications

(5 citation statements)

References 15 publications

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“…To conduct the refracto-vibrometry, a laser-Dopplerscanning vibrometer (LDV) PSV-500 from Polytec 1 is used to measure the changes of the refraction index of the fluid, which is proportional to the acoustic pressure variation within the cavity [44][45][46]. Overall, 225 measurement points were sequentially recorded with a sampling frequency of 50 kHz for a duration of 2 ms, while the measurements were triggered by the sinusoidal sound generator working at 2083.65 Hz.…”

Section: Resultsmentioning

confidence: 99%

Direct visualization of a Friedrich-Wintgen quasi-bound state in the continuum

Kronowetter

Maeder

Chiang

et al. 2023

Preprint

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Bound states in the continuum (BICs) are a well known phenomenon in physics, particularly in quantum physics and wave physics. Since BICs are local states, their existence typically manifests as Fano resonances in the transmission or reflection spectrum. However, to date no direct or visual proof of an acoustic BIC has been reported. We demonstrate the existence of a Friedrich-Wintgen BIC in an open acoustic cavity by theory and experiments. The appearance of the BIC is characterized by the vanished line width of the Fano resonance in the measured transmission spectrum. Our theoretical predictions accurately match the experimental observations. We map the pressure field of the transparent open cavity hosting a Friedrich-Wintgen BIC using laser Doppler vibrometry, which is the first reported visualization of an acoustic BIC. Mapping the pressure field of the BIC is a new technique to extract real sound pressure values of high-Q modes. We can draw conclusions from the pressure values on the confinement of the BIC. Our results facilitate the future development of applications of BICs in the field of acoustics, as acoustic sources, filters, and sensors.

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Section: Resultsmentioning

confidence: 99%

Direct visualization of a Friedrich-Wintgen quasi-bound state in the continuum

Kronowetter

Maeder

Chiang

et al. 2023

Preprint

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show abstract

“…To conduct the refracto-vibrometry, a laser Doppler scanning vibrometer PSV-500 from Polytec (Polytec Gmbh, Waldbronn, Germany) is used to measure the changes of the refractive index of the fluid, which is proportional to the acoustic pressure variation within the cavity 43 – 46 : where ω is the angular frequency, v is the LDV velocity, p is the sound pressure, n 0 is the refractive index of air at standard atmospheric pressure, p 0 is the static atmospheric pressure, and γ is the specific heat capacity ratio of air. The basic principle of the LDV is based on the well-known Doppler shift.…”

Section: Resultsmentioning

confidence: 99%

Section: Visualization Of Qbicmentioning

confidence: 99%

Realistic prediction and engineering of high-Q modes to implement stable Fano resonances in acoustic devices

Kronowetter,

Maeder,

Chiang

et al. 2023

Nat Commun

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Quasi-bound states in the continuum (QBICs) coupling into the propagating spectrum manifest themselves as high-quality factor (Q) modes susceptible to perturbations. This poses a challenge in predicting stable Fano resonances for realistic applications. Besides, where and when the maximum field enhancement occurs in real acoustic devices remains elusive. In this work, we theoretically predict and experimentally demonstrate the existence of a Friedrich-Wintgen BIC in an open acoustic cavity. We provide direct evidence for a QBIC by mapping the pressure field inside the cavity using a Laser Doppler Vibrometer (LDV), which provides the missing field enhancement data. Furthermore, we design a symmetry-reduced BIC and achieve field enhancement by a factor of about three compared to the original cavity. LDV measurements are a promising technique for obtaining high-Q modes’ missing field enhancement data. The presented results facilitate the future applications of BICs in acoustics as high-intensity sound sources, filters, and sensors.

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“…One-or two-dimensional sound propagation is often assumed to optically characterize pressure fields. [23][24][25][26][27][28][29][30][31][32] Alternatively, tomographic techniques (as in x-ray tomography) can reconstruct arbitrary pressure fields over space provided that enough projections are measured. However, the application of acousto-optic tomography has been limited by the reliance on reconstruction algorithms originally developed for medical tomography, such as filtered backprojection (FBP).…”

Section: Introductionmentioning

confidence: 99%

Acousto-optic holography

Verburg

Williams

Fernández-Grande

2022

The Journal of the Acoustical Society of America

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Acousto-optic sensing is based on the interaction between sound and light: pressure waves induce density variations, which, in turn, alter the way light propagates in air. Pressure fields are, thus, characterized by measuring changes in light propagation induced by pressure waves. Although acousto-optic sensing provides a way of acquiring acoustic information noninvasively, its widespread application has been hindered by the use of reconstruction methods ill-suited for representing acoustic fields. In this study, an acousto-optic holography method is proposed in which the sound pressure in the near field of a source is captured via acousto-optic sensing. The acousto-optic measurements are expanded into propagating and evanescent waves, as in near-field acoustic holography, making it possible to completely characterize the radiated field noninvasively. An algebraic formulation of the wave expansion enables the use of arbitrary sets of projections. The proposed method is demonstrated experimentally by capturing the acoustic field radiated by a vibrating plate. Accurate holographic reconstructions of the pressure, particle velocity, and intensity fields are obtained using purely optical data. These results are particularly significant for the study of sound fields at mid and high frequencies, where using conventional transducers could perturb the measured field and spatial sampling requirements are challenging.

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Experimental analysis of acoustical properties of irregular cavities using laser refracto-vibrometry

Cited by 6 publications

References 15 publications

Direct visualization of a Friedrich-Wintgen quasi-bound state in the continuum

Direct visualization of a Friedrich-Wintgen quasi-bound state in the continuum

Realistic prediction and engineering of high-Q modes to implement stable Fano resonances in acoustic devices

Acousto-optic holography

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