Analyse d'objets réfractants par interférométrie holographique de speckle

Cette communication présente une comparaison entre l'holographie numérique et l'holographie image pour la visualisation et la mesure d'indice de réfraction produits dans des milieux transparents mais fortement réfractant. L'évolution dans le temps de l'allumage d'une ampoule est utilisée comme cas test.International audienceThe authors present an optical method based on digital holographic interferometry to visualize and measure the refractive index variations occurring inside a transparent and refracting object. The aim is, in future, to reconstruct the evolution in time of the 3D convection currents or the thermal gradients inside a lighting bulb. Some convincing results have been already obtained for analyzing the variations of the refracting index occurring inside transparent object but not strongly refracting. For that, a tomographic optical bench having six different sights of view has been built and convincing results of 3D gas density reconstruction have been obtained in helium jets and small supersonic jets issuing from 3D shape nozzles. In this paper, the authors expose the advantages and disadvantages of speckle holographic bench, the aim being to reconstruct the 3D flow of a spherical field of 100mm in diameter. The authors also propose an optical solution to bring closer the sensor from the object. The limits of this optical technique and the effect on the resolution are discussed