Detection of echoes from the multilayer structures by using the wavelet transform

A method, based on echo detection by means of the wavelet transform, for measuring unknown thicknesses of multilayer structures is presented. Brief theoretical considerations underlying the method are first reported. They highlight the high performance shown by the wavelet transform as a powerful analysis tool of echoes in noisy environment. Then, a suitable operative procedure for the method validation when a standard multilayer structure is not available, is set up and discussed. To this aim tests on (i) simulated signals and (ii) actual signals back from known thicknesses are carried out. Finally, experimental results obtained by the measurement method application to unknown thicknesses referred to the echo-ophthalmic field, are also reported.