Discrete Time Model for Bond Detection in Thin Layer Materials

Recursive equations were developed and introduced that enable to calculate the transmitted waves through a multiplicity of layers. The calculations are carried out using z-transform technique. The layers are considered lossless and have parallel interface, which are at normal incidence to the field. The multilayered structures are constructed of three aluminum plates connected together with epoxy as the adhesive layers. The method has been successfully used to detect small changes in the thickness of adhesive layers.