OPTICAL TOMOGRAPHY OF REAL 3-DIMENSIONAL FOAMS

Optical tomography has been implemented as a nondestructive method for investigating the structure of real three-dimensional polyhedral soap foams. Images of successive slices of the transparent foam are obtain ed by means of a CCD camera equipped with a very thin depth-of-field o bjective, and the coordinates of the foam vertices are determined. The 3D foam is then numerically reconstructed using surface energy minimi zation software to calculate the volume, the area, and the isoperimetr ic quotient of each bubble. This optical tomography has been used on a four bubbles thick layer of foam at two different capillary pressures in order to get a dry foam and a wet foam with similar topology. The evolution of the foam morphology upon drainage has been investigated. The network of the Plateau borders of the wet foam was also reconstruc ted, assuming that the Plateau borders are like prism and the vertices are like octahedra. If the liquid volume is neglected in the films, t he liquid fraction of the wet foam can be directly evaluated. (C) 1998 Academic Press.