Ref HAL: hal-00740782_v1
Ref Arxiv: 1210.3182
DOI: 10.1364/OE.20.022860
WoS: 000309522400103
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
10 Citations
Résumé:

We propose here to combine sideband holography with stroboscopic illumination synchronized with the vibration of an object. By sweeping the optical frequency of the reference beam such a way the holographic detection is tuned on the successive sideband harmonic ranks, we are able to image the instantaneous velocities of the object. Since the stroboscopic illumination is made with an electronic device, the method is compatible with fast (up to several MHz) vibration motions. The method is demonstrated with a vibrating clarinet reed excited sinusoidally at 2 kHz, and a stroboscopic illumination with cyclic ratio 0.15. Harmonic rank up to n = ±100 are detected, and a movie of the instantaneous velocities is reported.

Ref HAL: hal-00668277_v2
Ref Arxiv: 1202.2114
DOI: 10.3813/AAA.918735
WoS: 000334492900018
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
13 Citations
Résumé:

A set of 55 clarinet reeds is observed by holography, collecting 2 series of measurements made under 2 different moisture contents, from which the resonance frequencies of the 15 first modes are deduced. A statistical analysis of the results reveals good correlations, but also significant differences between both series. Within a given series, flexural modes are not strongly correlated. A Principal Component Analysis (PCA) shows that the measurements of each series can be described with 3 factors capturing more than $90\%$ of the variance: the first is linked with transverse modes, the second with flexural modes of high order and the third with the first flexural mode. A forth factor is necessary to take into account the individual sensitivity to moisture content. Numerical 3D simulations are conducted by Finite Element Method, based on a given reed shape and an orthotropic model. A sensitivity analysis revels that, besides the density, the theoretical frequencies depend mainly on 2 parameters: $E_L$ and $G_{LT}$. An approximate analytical formula is proposed to calculate the resonance frequencies as a function of these 2 parameters. The discrepancy between the observed frequencies and those calculated with the analytical formula suggests that the elastic moduli of the measured reeds are frequency dependent. A viscoelastic model is then developed, whose parameters are computed as a linear combination from 4 orthogonal components, using a standard least squares fitting procedure and leading to an objective characterization of the material properties of the cane \textit{Arundo donax}.

Ref HAL: hal-00741011_v1
Ref Arxiv: 1210.3326
DOI: 10.1117/12.896523
WoS: 000293625400032
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé:

In this paper we present a digital holographic microscope to track gold colloids in three dimensions. We report observations of 100nm gold particles in motion in water. The expected signal and the chosen method of reconstruction are described. We also discuss about how to implement the numerical calculation to reach real-time 3D tracking.

Ref HAL: hal-00740865_v1
Ref Arxiv: 1210.3188
DOI: 10.1117/12.889504
WoS: 000293625400004
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé:

The 3D structure of light scattering from dark-field illuminated live 3T3 cells marked with 40 nm gold nanomarkers is explored. For this purpose, we use a high resolution holographic microscope combining the off-axis heterodyne geometry and the phase-shifting acquisition of the digital holograms. Images are obtained using a novel 3D reconstruction method providing longitudinally undistorted 3D images. A comparative study of the 3D reconstructions of the scattered fields allows us to locate the gold markers which yield, contrarily to the cellular structures, well defined bright scattering patterns that are not angularly titled and clearly located along the optical axis. This characterization is an unambiguous signature of the presence of the gold biological nanomarkers, and validates the capability of digital holographic microscopy to discriminate them from background signals in live cells.

Ref HAL: hal-00653907_v1
PMID 22274193
Ref Arxiv: 1112.4737
DOI: 10.1364/OE.19.026044
WoS: 000301151500023
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
70 Citations
Résumé:

We present a new technique that combines off-axis Digital Holography and Dark Field Microscopy to track 100nm gold particles diffusing in water. We show that a single hologram is sufficient to localize several particles in a thick sample with a localization accuracy independent of the particle position. From our measurements we reconstruct the trajectories of the particles and derive their 3D diffusion coefficient. Our results pave the way for quantitative studies of the motion of single nanoparticle in complex media.

Ref HAL: hal-00602181_v2
Ref Arxiv: 1106.4890
DOI: 10.1364/JOSAA.28.001436
WoS: 000292456400014
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
10 Citations
Résumé:

Acousto-Optical Coherence Tomography (AOCT) is variant of Acousto Optic Imaging (called also ultrasonic modulation imaging) that makes possible to get z resolution with acoustic and optic Continuous Wave (CW) beams. We describe here theoretically the AOCT e ect, and we show that the Acousto Optic tagged photons remains coherent if they are generated within a speci c z region of the sample. We quantify the z selectivity for both the tagged photon eld, and for the M. Lesa re et al. photorefractive signal.

Ref HAL: hal-00578035_v1
Ref Arxiv: 1103.3592
DOI: 10.1364/OL.36.001449
WoS: 000290034500048
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
18 Citations
Résumé:

We report a demonstration video-rate heterodyne holography in off-axis configuration. Reconstruction and display of 1 Megapixel holograms is achieved at 24 frames per second, with a graphics processing unit. Our claims are validated with real-time screening of steady-state vibration amplitudes in a wide-field, non-contact vibrometry experiment.