A new angular spectrum approach for modelling the acoustic microscope response with high attenuation coupling fluids

The angular spectrum of an acoustic lens of large aperture angle is calculated by integration of the field directly on the surface of the lens cavity. In contrast to the customary method, where the distribution of the acoustic field on the flat aperture of the lens is assumed to be known, the new method makes no such assumptions. The calculated V(z) based on this angular spectrum shows good agreement with published experimental data. Also, the distribution of the reflected field on the surface of a spherical lens throughout a typical z scan is calculated. This gives new insight into ray models of an acoustic lens. Implications for the case of high attenuation, low speed coupling fluids for use in micro-mechanical characterization of polymers are explored.