Steered nonlinear field computation and measurement

One order parabolic approximation KZK equation is considered to be reliable inside ±15 degree relative to the KZK centerline, so KZK equation is unsuitable for studying steered beams in its classical configuration of having beam axis aligned with transducer central axis. An equivalent parametric array model was proposed based on the collimation characteristic of primary field, so the problem of steered beams calculation using KZK equation is converted to source condition calculation of equivalent parametric array. In this paper, a time domain solution of KZK equation for rectangular source is used to calculate steered nonlinear beams, the natural directivity beam calculated under this model is compared with classical KZK approach, and the influence of the distance between the center of parametric array and equivalent parametric array in calculating steered nonlinear field is analyzed at the same time. Finally, comparison is made between the calculated and measured steered nonlinear field which shows that the equivalent parametric array model is an effective theory model in steered nonlinear beams computation, and this research gives a helpful direction to the future study.