Contrast Formation for Simple Shaped Objects in Acoustic Microscopy

Abstract

Reconstruction of 3-dimensional objects in Scanning Acoustic Microscopy (SAM) is now of great interest. From the mathematical point of view, the simplest kind of 3- dimensional objects are spherical particles, Investigations of the image formation of spheres have revealed different phenomena, which are of current scientific concern. First theoretical treatments1 showed that the image formation of spheres in transmission configuration of SAM is easily to understand, and is close to the imaging in optical microscopy. In transmission acoustic microscopy, the dimension of the image is only slightly dependent on the scanning plane position. The strongest image contrast arises when the focal plane coincides with the center of the sphere. The diameter of the image in this position is nearly equal to the particle size. In contrary, in reflection acoustic microscopy, image formation of spherical particles has revealed extraordinary properties2,3. The purpose of this report is to present an interpretation of the images of spheres at different focal plane positions, using Fourier spectrum approach in reflection SAM.