ИСТИНА

Tomography of the acoustic nonlinear parameters is a method of obtaining information about biological tissue using nonlinear interaction of acoustic waves. In the schemes under consideration, three plane coded non-collinear signals probe an investigated object and intersect inside it. Each point of the intersection region generates coded signal at the third-order combination frequencies. Correlation processing of received total signal allows determining the combination of the second- and third-order acoustic nonlinear parameters in each resolution element of the object. Results of physical experiment on reconstructing the spatial distribution of the combined acoustic nonlinear parameter by the scheme with one monochromatic and two coded probing signals are presented. Principal disadvantage of this scheme is nonlocality of generation area of the unique coded combination signal carrying information about the object. This makes it impossible to distinguish the signal generated by the only fixed resolution element of the object. As a consequence, reconstructed quantitative values of the nonlinear parameters can be distorted. The next step is the scheme with three coded probing signals, that is more complex for implementation. Nevertheless, now each unique signal is generated by the single resolution element. Thereby, it becomes possible to adequately reconstruct the desired values of nonlinear parameters.