A Reversible Jump MCMC Algorithm for Particle Size Inversion in Multiangle Dynamic Light Scattering

Publication in the conference proceedings of EUSIPCO, Lisbon, Portugal, 201

Agrégation fractale de suspensions colloïdales déstabilisées : analyse par diffusion multi-angulaire de la lumière

International audienceCette communication expose les principales caractéristiques d’un banc de diffusion multi an-gulaire dont les aspects novateurs et la pertinence sont testés par le suivi de la dynamique de déstabilisation d’une suspension de silice. Outre la correction de divers biais optiques, ce banc intègre des algorithmes d’inversion couplant modèles d’agrégation fractale, modèles de diffusion de la lumière et méthodes d’inversion des données expérimentales. Les résultats obtenus sont jugés très physiques et dans tous les cas bien plus résolus et riches que ceux restitués par des analyses classiques du type microscopie électronique et diffusion dynamique

Thermoelastic investigation of a quartz tuning fork used in infrared spectroscopy

International audienceThe performances of quartz tuning forks (QTF) used in infrared spectroscopy for pollutant detection are investigated. The transduction between light and QTF vibration is elucidated thanks to QTF encapsulation under vacuum. From the sensitivity enhancement which is obtained we conclude that their interaction is photo-thermoelastic rather than photo-thermoacoustic. A mapping of the local sensitivity of the QTF is obtained by scanning its faces with the excitation probe beam. The comparison between the signal mapping and the theoretical strain mapping indicates that the most efficient areas of the QTF correspond to the areas where the strain or stress are the highest

Agrégation fractale de suspensions colloïdales déstabilisées : analyse par diffusion multi-angulaire de la lumière

International audienceCette communication expose les principales caractéristiques d’un banc de diffusion multi an-gulaire dont les aspects novateurs et la pertinence sont testés par le suivi de la dynamique de déstabilisation d’une suspension de silice. Outre la correction de divers biais optiques, ce banc intègre des algorithmes d’inversion couplant modèles d’agrégation fractale, modèles de diffusion de la lumière et méthodes d’inversion des données expérimentales. Les résultats obtenus sont jugés très physiques et dans tous les cas bien plus résolus et riches que ceux restitués par des analyses classiques du type microscopie électronique et diffusion dynamique

Study of sintering mechanisms of Ca-doped yttrium aluminum garnet ceramics: From nanostructure to macroscopic behaviour

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Fluorescence scanning near-field optical microscopy in reflection

A Fluorescence Scanning Near-Field Optical Microscope operated in reflection is presented. A pulled optical fiber is used both as an emitter for the exciting light and a collector for the generated fluorescence. The advantage of this set-up is the use of the fiber tip as an emitter and a collector. The sample is locally illuminated and no extra optical elements are needed for the detection. We will describe the shear force set-up which is used to control the tip to surface distance. Direct correlation between force map and optical signal is thus possible. Fluorescence images have been obtained on Langmuir-Blodgett films where we estimate the resolution at 200 nm. Moreover the anisotropic property of the monolayer allows polarization contrast measurements. Thus, we show true optical contrast due to fluorescence and polarization is applicable to this configuration. Artifacts in LB films shear force image are discussed. Shear force approach curves obtained on glass and polymer domains are presented to explain the chemical origin of the phenomenon

An improved Bayesian inversion method for the estimation of multimodal particle size distribution using multi-angle dynamic light scattering measurements

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Emission of 30ps Pulses by a Fibered Passively Q-Switched Microchip Laser

International audienceWe report the design of low-cost and compact short-pulse source based on a fiber-coupled Q-switched microchiplaser. The combination of stimulated Raman scattering and non linear polarization rotation effects in the fiber associated with appropriate filtering makes it possible to tune pulse duration down to 32ps with peak power above 3kW. Pulse to pulse peak power fluctuation is below 4%

Assessment of two MCMC algorithms convergence for Bayesian estimation of the particle size distribution from multiangle dynamic light scattering measurements

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