The integrated second harmonic component in an acoustic microscope

A fast algorithm is presented to compute the integrated fundamental and second harmonic pressure fields of a focused source. Typically, the calculated results are given for three kinds of spherically focused sources, and the main properties of the integrated field are described for the fundamental and second harmonic components. An experimental measurement is made of the integrated second harmonic amplitude with the variation of axial distance in an acoustic microscope, in good agreement with the theoretical prediction. Moreover, a procedure of the B/A measurement or imaging by acoustic microscopy is suggested.