THE THEORY OF 3-DIMENSIONAL IMAGING OF STRONG SCATTERERS IN SCANNING ACOUSTIC MICROSCOPY

The angular spectrum approach to three-dimensional image formation of strong scatterers in scanning acoustic microscopy is developed, It is shown that in the case of strong scatterers the image can be represent ed as a twofold two-dimensional Fourier transform of a far field scatt ering amplitude of the object. The proposed theory provides the opport unity to investigate the imaging process for objects having an arbitra ry shape. The common features of images are demonstrated by using a di sk and an elastic sphere as examples. It is shown that contrast in ref lection microscopy is mainly due to scattering from the boundary of th e object and can be described as a thin layer whose medium surface is in coincidence with the boundary of the objects. The thickness of the layer is equal to the lateral resolution of the microscope. For transm ission acoustic microscopes the contrast is connected with the contour of the object.