Ref HAL: hal-00840516_v1
Ref Arxiv: 1307.1209
DOI: 10.1364/DH.2013.DTh3A.5
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Playing with amplitude, phase and frequency of both reference and signal arms, heterodyne holography is well adapted to vibration analysis. Vibration sidebands can be imaged and stroboscopic measurement sensitive to mechanical phase can be made

Ref HAL: hal-00840804_v1
DOI: 10.1103/PhysRevLett.111.058302
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41 Citations
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We report theoretical predictions and measurements of the capillary force acting on a spherical colloid smaller than the capillary length that is placed on a curved uid interface of arbitrary shape. By coupling direct imaging and interferometry, we are able to measure the in situ colloid contact angle and to correlate its position with respect to the interface curvature. Extremely tiny capillary forces down to femto-Newton can be measured with this method. Measurements agree well with a theory relating the capillary force to the gradient of Gaussian curvature and to the mean curvature of the interface prior to colloidal deposition. Numerical calculations corroborate these results.

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By using the dark field holographic microscopy technique described in Opt. Express, 19 pp 26044-26055 (2011) we have track gold particles in brownian motion in living cells. First results are presented. The particles remain confined to a region a few microns in size. We interpret this as a cage effect related to the cell structure.

Ref HAL: hal-00785372_v1
Ref Arxiv: 1302.1343
DOI: 10.1364/AO.52.000949
WoS: 000314842400005
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2 Citations
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Acousto-Optical Coherence Tomography (AOCT) is a variant of Acousto Optic Imaging (also called Ultrasound modulated Optical Tomography) that makes possible to get resolution along the ultrasound propagation axis $z$. We present here new AOCT experimental results, and we study how the $z$ resolution depends on time step between phase jumps $T_\phi$, or on the correlation length $\Delta z$. By working at low resolution, we perform a quantitative comparison of the $z$ measurements with the theoretical Point Spread Function (PSF). We present also images recorded with different $z$ resolution, and we qualitatively show how the image quality varies with $T_\phi$, or $\Delta z$.

Ref HAL: hal-00756128_v2
Ref Arxiv: 1211.5428
DOI: 10.1364/OL.38.000377
WoS: 000314629600047
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4 Citations
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We report a demonstration of phase-resolved vibrometry, in which out-of-plane sinusoidal motion is assessed by heterodyne holography. In heterodyne holography, the beam in the reference channel is an optical local oscillator (LO). It is frequency-shifted with respect to the illumination beam to enable frequency conversion within the sensor bandwidth. The proposed scheme introduces a strobe LO, where the reference beam is frequency-shifted and modulated in amplitude, to alleviate the issue of phase retrieval. The strobe LO is both tuned around the first optical modulation side band at the vibration frequency, and modulated in amplitude to freeze selected mechanical vibration states sequentially. The phase map of the vibration can then be derived from the demodulation of successive vibration states.

Ref HAL: hal-00741432_v1
Ref Arxiv: 1210.3944
DOI: 10.1364/AO.52.000A81
WoS: 000313745800009
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20 Citations
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We have performed off axis heterodyne holography with very weak illumination by recording holograms of the object with and without object illumination in the same acquisition run. We have experimentally studied , how the reconstructed image signal (with illumination) and noise background (without) scale with the holographic acquisition and reconstruction parameters that are the number of frames, and the number of pixels of the reconstruction spatial filter. The first parameter is related to the frequency bandwidth of detection in time, the second one to the bandwidth in space. The signal to background ratio varies roughly like the inverse of the bandwidth in time and space. We have also compared the noise background with the theoretical shot noise background calculated by Monte Carlo simulation. The experimental and Monte Carlo noise background agree very well together.

Ref HAL: hal-00741034_v1
Ref Arxiv: 1210.3328
DOI: 10.1364/OL.37.003216
WoS: 000307226700070
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10 Citations
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Acousto-optical coherence tomography (AOCT) consists in using random phase jumps on ultrasound and light to achieve a millimeter resolution when imaging thick scattering media. We combined this technique with heterodyne off-axis digital holography. Two-dimensional images of absorbing objects embedded in scattering phantoms are obtained with a good signal-to-noise ratio. We study the impact of the phase modulation characteristics on the amplitude of the acousto-optic signal and on the contrast and apparent size of the absorbing inclusion.