Abstract
The two-dimensional thickness distribution of a thin liquid film formed between solid and bubble surfaces is measured using the laser interferometer. A time development of the film thickness distribution is analyzed from the fringe patterns. Furthermore, small amount of surfactant is added into the liquid phase to investigate the stability of the liquid film. The experimental apparatus is design so as to control the approaching speed of a bubble which is attached to the tip of a steel pipe toward the glass surface. He-Ne laser is used as a light source so that the vertical interval of fringes becomes 0.24μm for water, which enables the thickness measurement of sub-micro-meter order. Surfactant stabilizes the thin liquid film, and prevents the gas phase from attaching to the solid surface. This phenomenon is mainly caused by the surface tension reduction and Marangoni effect that reduce the film drainage. When the bubble approaches slowly, axisymmetric shapes of films are formed, and eventually the liquid film becomes dimple shape. On the other hand, the faster approaching speed leads to the asymmetric interfacial shape.
