Investigation for the focussing of acoustic beam generated by a Fresnel array on solid surface

The B-scanning of focused acouStic beam in solid by a Fresnel array is realized. The analyses of the elastic wave fields generated by such an array on solid surface lay the physical foundation for the B-scanning foraging of focused acoustic beams in solid. In the paper, complete analyses for such focusing acoustic fields have been given. Our analyses include that the frequency-scanning characteristics for convergence acoustic beams; the amplitude distributions of longitudinal wave fields along focal tris and on focal plane; the frequency response at the principal focus; all-space distributions of longitudinal wave field and the effects of array parameters on the convergence acoustic fields. Finally, the transversal wave distributions are discussed also.