A NOVEL TECHNIQUE FOR THE MEASUREMENT OF STRESS IN THIN METALLIC-FILMS

A novel interferometric method for determining mechanical stress in va cuum-deposited thin metallic layers on glass substrates is described. Stress in the glass-metal structure affects the curvature and hence th e resonant frequencies of the substrate. Thus, by measuring variations of the resonant frequencies, the curvature and hence the stress can b e determined. The technique of photo-thermoelastic bending has been ad apted to this measurement. Measuring the variation in resonant frequen cy is a very sensitive method of determining the substrate curvature. Tests of the new technique using thin Cr films on glass demonstrate it s effectiveness.