Acoustic microscopes have been constructed using transducers in the shape of spherical caps. The focal plane fields and V(z) response for these spherical transducers have been studied previously with the help of Fourier optics. The authors report on a complementary study of the V(z) response based on ray optics. The ray approach accounts for the contributions to the output voltage due to the acoustic fields geometrically reflected from the object surface, and for the contribution due to the leaky Rayleigh wave excited on the surface. The effects of diffraction are included for transducers with a step pupil function, while apodization is taken into account for transducers with a continuous pupil function.
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