Interferometric thickness measurements on transparent thin films

Abstract

The interpretation of interferometric thickness measurements made on uncoated transparent thin films is complicated by the occurrence of multiple reflections between the upper and lower surfaces of the film. Some of the effects that can occur are described and illustrated, and a simple method for calculating their magnitude is presented. Particular attention is drawn to the behaviour of fringes at the edge of an absorbing film; in this instance, interpretation of the fringe displacement in terms of film thickness may be impossible.