Abstract The focusing properties of the lenses used in the scanning acoustic microscope (SAM) have been widely studied for the particular case of surface imaging. When focusing into the bulk of a sample the aberration of the lens become negligible with respect to that induced by the sample surface traversal. A more detailed study allows evaluation of the acoustic field distribution, using an angular spectrum expansion. This formalism, previously developed by several independent authors, is used for optimizing the geometrical parameters of the acoustic lens for non-destructive testing of ceramic materials. The deduced theoretical performances are compared with experimental findings at a working frequency of 100 MHz. Characteristic images for some ceramic materials are presented, which give valuable information about the geometry of the defects and the structure of the matrix material.A comparison with alternative non-destructive testing methods is also given.
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