title: Synchronized diffusive-wave spectroscopy: Principle and application to sound propagation in aqueous foams.
abstract: We present an experimental method to measure oscillatory strains in turbid material. The material is illuminated with a laser, and the speckle patterns are recorded. The analysis of the deformations of the optical path length shows that the speckle patterns are modulated at the strain frequency. By recording those patterns synchronously with the strain source, we are able to measure the amplitude and the phase of the strain. This method is tested in the specific case of an aqueous foam where an acoustic wave propagates. The effects of material internal dynamics and heterogeneous deformations are also discussed.
authors.affiliation: Institut de Physique de Rennes, UMR CNRS 6251, Université de Rennes 1, Campus de Beaulieu, F-35042 Rennes Cedex, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Crassous
authors.affiliation: Institut de Physique de Rennes, UMR CNRS 6251, Université de Rennes 1, Campus de Beaulieu, F-35042 Rennes Cedex, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Chasle
authors.affiliation: Institut de Physique de Rennes, UMR CNRS 6251, Université de Rennes 1, Campus de Beaulieu, F-35042 Rennes Cedex, France.
authors.forename: Juliette
authors.initials: J
authors.lastname: Pierre
authors.affiliation: Institut de Physique de Rennes, UMR CNRS 6251, Université de Rennes 1, Campus de Beaulieu, F-35042 Rennes Cedex, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Saint-Jalmes
authors.affiliation: Institut de Physique de Rennes, UMR CNRS 6251, Université de Rennes 1, Campus de Beaulieu, F-35042 Rennes Cedex, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Dollet