Christophe Baravian
Centre national de la recherche scientifique
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Featured researches published by Christophe Baravian.
Applied Optics | 2006
Jérôme Dillet; Christophe Baravian; François Caton; Alan L. Parker
Here we are concerned with the systematic study of polarized light transport in thick, isotropic, homogeneous random media and of the associated inverse problem. An original spatial and intensity rescaling of the polarization transport allows one to account implicitly for the volume fraction. This parameter elimination permits a complete exploration, by means of Monte Carlo simulations of the dependence of polarized light transport on microscopic parameters. Analysis of the Mueller matrices obtained from the simulations show that additional correlations (with respect to scalar transport) are obtained between the microscopic parameters and the spatial distribution of specific elements of the Mueller matrix. As a consequence, using carefully chosen polarization states, one can determine an average particle size independently of the volume fraction of particles, with only the knowledge of the refractive-index ratio being required. This analysis is validated with experimental Mueller matrices obtained for emulsions of various size, concentration, and polydispersity.
Optics Express | 2007
François Caton; Christophe Baravian; Julien Mougel
In this paper the influence of the microscopic characteristics of a random medium on non polarized, incoherent steady light transport (ISLT) is investigated. After close examination of current diffusion models, the source term in those models is modified, allowing a complete modeling of experimental and simulated radial dependance of backscattered and transmitted intensities for media thicknesses larger than the transport length. The new model only presents an additional source with respect to the elementary point source model. Thanks to more than 200 Monte-Carlo simulations, this parameter is correlated to the backscattering part of the Mie phase function. Incoherent Steady Light Transport measurements on two industrial emulsions at various volume fractions validate experimentally this correlation. This establishes a complete link between the microscopic characteristic of the random medium (size, optical indexes and volume fraction) and its macroscopic description in terms of diffusion and source parameters, opening new potential applications of the ISLT technique to, for example, the evaluation of the particles interaction potential in concentrated suspensions.
Journal of Colloid and Interface Science | 2010
Emilio Paruta-Tuarez; Hala Fersadou; Véronique Sadtler; Philippe Marchal; Lionel Choplin; Christophe Baravian; Christophe Castel
The analysis of incoherent polarized steady light transport is reported as a convenient technique for the drop size determination in highly concentrated oil-in-water emulsions. The studied system consists in heptane-in-water emulsions stabilized with a copolymeric surfactant (Synperonic PE®/L64). Hundred grams of parent emulsions, at two volume fractions of dispersed phase (φ=0.958 and 0.937) were prepared using a semi-batch process. Then, they were diluted with the aqueous phase to obtain volume fractions ranging from 0.886 to 0.958. The use of a copolymeric surfactant allows the dilution of the highly concentrated emulsions without any change in the particle size distribution as confirmed by laser diffraction measurements. We found that the polarization technique allows the determination of the film thickness between water drops rather than their sizes. Consequently, we propose a geometrical relationship to determine an average drop size from the film thickness. The sensitivity of this alternative technique to detect changes in average drop size was studied by changing some process and formulation parameters. Drop size determination in highly concentrated emulsions via this method is useful since the measurement protocol neither involves dilution nor induces structural changes in the emulsion.
Rheologica Acta | 2008
François Caton; Christophe Baravian
Rheologica Acta | 1998
Christophe Baravian; D. Quemada
Rheologica Acta | 2010
G. Benmouffok-Benbelkacem; F. Caton; Christophe Baravian; S. Skali-Lami
Rheologica Acta | 2007
Christophe Baravian; Ghania Benbelkacem; François Caton
Physical Review E | 2005
Christophe Baravian; François Caton; Jérôme Dillet; Julien Mougel
Rheologica Acta | 2006
Julien Mougel; Óscar Álvarez; Christophe Baravian; François Caton; Philippe Marchal; Marie-José Stébé; Lionel Choplin
Rheologica Acta | 2004
Christophe Baravian; François Caton; Jérôme Dillet