The accuracy of pupil function measurement in reflection acoustic microscope by imaging spherical particles

The determination of the modulus of the pupil function in reflection acoustic microscopy with the help of rigid spherical particles is demonstrated. The theoretical examination, based on ray theory, shows that this method can give good results for a lens if the pupil function drops smoothly towards the edge. For a pupil with a sharp edge this technique can give the accurate pupil function only by imaging large spheres. The accuracy of the method increases with increasing aperture angle. The dependence of the accuracy on the size of the spherical particle is also analyzed. Measurements are presented