Ref HAL: hal-01202128_v1
DOI: 10.1038/NMAT4348
WoS: 000360192000024
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74 Citations
Résumé:

The dynamics of colloidal particles at interfaces between two fluids plays a central role in microrheology, encapsulation, emulsification, biofilm formation, water remediation and the interface-driven assembly of materials. Common intuition corroborated by hydrodynamic theories, suggests that such dynamics is governed by a viscous force lower than that observed in the more viscous fluid. Here, we show experimentally that a particle straddling an air/water interface feels a large viscous drag that is unexpectedly larger than that measured in the bulk. We suggest that such a result arises from thermally activated fluctuations of the interface at the solid/air/liquid triple line and their coupling to the particle drag through the fluctuation–dissipation theorem. Our findings should inform approaches for improved control of the kinetically driven assembly of anisotropic particles with a large triple-line-length/particle-size ratio, and help to understand the formation and structure of such arrested materials.

Ref HAL: hal-01181347_v2
Ref Arxiv: 1507.08399
DOI: 10.1103/PhysRevB.93.161114
WoS: WOS:000374952800001
Ref. & Cit.: NASA ADS
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5 Citations
Résumé:

Due to the existence of open channels, light could theoretically be transmitted through disorderedmedia with 100% efficiency. However, because of the large number of channels to be controlledor measured, this has been never observed experimentally. To avoid this difficulty we considerobservables easier to handle experimentally. By measuring the correlations of the field transmittedthrough a disordered medium, we were able to count the number of channels involved in transmissionand to compare this number with theory. For a sample of transmission 1=25, we get a number ofmodes about 15 times smaller than for free space propagation. This figure is in good agreementwith theoretical prediction.

Ref HAL: hal-01111198_v1
Ref Arxiv: 1501.07555
DOI: 10.1364/OL.40.000411
WoS: 000349162000030
Ref. & Cit.: NASA ADS
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6 Citations
Résumé:

Sideband holography can be used to get fields images (E0 and E1) of a vibrating object for both the carrier (E0) and the sideband (E1) frequency with respect to vibration. We propose here to record E0 and E1 sequentially, and to image the correlation E1E * 0 . We show that this correlation is insensitive the phase related to the object roughness and directly reflect the phase of the mechanical motion. The signal to noise can be improved by averaging the correlation over neighbor pixel. Experimental validation is made with vibrating cube of wood and with a clarinet reed. At 2 kHz, vibrations of amplitude down to 0.01 nm are detected.

Ref HAL: hal-01144722_v1
Ref Arxiv: 1506.05961
DOI: 10.1002/9781119091745
Ref. & Cit.: NASA ADS
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Résumé:

Heterodyne holography is an extremely versatile and powerful holographic technique that is able to fully control the amplitude, phase and frequency of both the illumination and holographic reference beams. Applied to vibration analysis, this technique is able to detect the signal of the carrier or the one of any vibration sideband. A complete analysis of the vibration signal can thus be made, and 2D map of the vibration amplitude and phase in all points of the surface of the vibrating object can be obtained. Since the sensitivity is limited by shot noise, extremely low vibration amplitude (< 0.01 nm) can be studied.

Ref HAL: hal-01112589_v1
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Résumé:

En jouant avec l'amplitude, la phase et la fréquence des deux bras référence et signal, l'holographie hétérodyne est bien adaptée à l'analyse des vibrations. Les bandes latérales de vibrations peuvent être visualiées et des mesures stroboscopiques, sensibles à la phase mécanique peuvent être faites.

Ref HAL: hal-01112617_v1
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Résumé:

Le couplage d'une méthode d'imagerie laser Doppler par holographie hétérodyne à un microscope commercial est proposé. Cette méthode permet d'obtenir, sans étape de calibration préalable, des images Doppler résolues à la fois en norme des vecteurs vitesses qu'en direction, ainsi que des contrastes d'amplitude de la chair ou de la vascularisation du zebrafish.

Ref HAL: hal-01083826_v1
Ref Arxiv: 1501.01609
DOI: 10.1364/AIO.2014.JTu4A.7
Ref. & Cit.: NASA ADS
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Résumé:

A laser Doppler imaging scheme combined to an upright microscope is proposed. Quantitative Doppler imaging in both velocity norm and direction, as well as amplitude contrast of either zebrafish flesh or vasculature is demonstrated.