Apparatus for film-thickness measurements of postwithdrawal drainage

Abstract

A method based upon laser interferometry is developed to measure the transient film-thickness profiles in the postwithdrawal drainage of viscoelastic suspensions. The interference patterns, produced by a Mach–Zender interferometric arrangement, were recorded and subsequently analyzed using a microcomputer which was interfaced with a number of photodetectors. Experimental verification of the new technique was established by examining Newtonian mixtures of glycerine and water. The experimental arrangement demonstrated greater accuracy than previously employed techniques of film-thickness measurement.