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Communication Dans Un Congrès Année : 2020

Wide-field vibration measurements from time-sequences of digital Fresnel holograms

Résumé

Digital holography is a contactless optical method which may yield observation and measurement of complex physical phenomena over a large field of view. Thus, high-speed digital holography is potentially a key technology to investigate vibrations of structures at their time scale when providing a large collection of data points at the surface of the studied sample. In this paper, we discuss on a robust and efficient holographic set-up working at 100kHz that makes possible to visualize transient waves generated by shocks whose bandwidth is around 30 kHz. The experimental set-up includes a compact holographic interferometer in the Fresnel configuration equipped with a negative zoom for large surfaces and a diffractive optical element (DOE) to improve the overall photometric efficiency. We propose a robust processing approach that permits to measure vibrations having very weak amplitude, in the range of 20nm, over a large field of view. We demonstrate the possibility of measuring the vibration of a plate with at 100 kHz frame rate when providing quantitative data on 450cm2 at the object surface sampled by about 55000 data points. This is the best performance ever achieved for such field-of-view and frame rate, to the best of our knowledge. The proposed approach is also applied to the investigation of traveling acoustic waves propagating in alloy plate equipped with a two-dimensional acoustic black hole (ABH). The observation of the modification of the wave propagation can be observed at very short time scale. The modification of the wave front due to the gradient in elastic properties related to the ABH area is also highlighted.
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Dates et versions

hal-03235502 , version 1 (25-05-2021)

Identifiants

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Erwan Meteyer, Pascal Picart, Silvio Montresor, Félix Foucard, Charles Pezerat. Wide-field vibration measurements from time-sequences of digital Fresnel holograms. Forum Acusticum, Dec 2020, Lyon, France. pp.583-583, ⟨10.48465/fa.2020.1113⟩. ⟨hal-03235502⟩
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