The detection of echoes from multilayer structures using the wavelet transform

A method fur measuring unknown thicknesses of multilayer structures, based on echo detection by means of the wavelet transform (WT), is presented. A b rief discussion of the theoretical considerations underlying the method is first given. This highlights the excellent performance shown by the WT as a powerful tool for the analysis of echoes in a noisy environment, A suitabl e operating procedure for validation of the method is then set up. To this end, tests on 1) simulated signals and 2) actual signals received from know n thicknesses are carried out; the obtained results are finally given and d iscussed.