Modeling propagation of laser-ultrasonic probing pulse in stratified medium by the method of ABCD matrices

Abstract

The modern methods of modeling acoustic wave travel in stratified media are reviewed, and the necessity of a new and faster technique is justified. The method of modeling elastic wave propagation based on signal conditioning using ABCD matrices and a Python soft ware is described. The theoretical framework and the mathematical algorithm of the presented method are discussed. The main calculations of the main physical and mathematical relations of the method implementation in the program are given. The model signal is correlated with the test signal obtained from a medium with pre-set parameters. The temporal shapes and spectra of the signal inside an optical-acoustic converter are presented for two cases. In the first case, the optical-acoustic converter has a free surface (boundary with air); in the second case, the optical-acoustic converter is pressed to a steel plate. Based on the obtained data, the applicability of the method to modeling acoustic signal propagation in flat and stratified medium is proved. The critical advantage of the proposed modeling approach is high calculating speed of the signal shape and spectrum at any point of the medium and at any assigned time.