Multi-element sources focusing energy

In underwater imaging the beam-forming technique plays one of the most important roles. Focusing acoustic energy is one of the methods used to improve lateral resolution. The paper contains the results of the experimental research in a piezoelectric four- and six-element annular arrays of a resonant frequency equal to 1.5 MHz. The third examined source is built using one PZT bowl element. The sources are constructed with a layer adjusting the PZT transducers to water. In that way we obtained the sources of broadened band radiating in the frequency range 1.2 MHz - 1.8 MHz. The space distribution of the pressure field has been determined for various frequencies and various intensity of the phenomenon of the non-linear distortion of the wave. The experimental data have been compared with the results of the numerical research carried out with the use of a model constructed on the basis of the KZK equation