Nonplanar surface characterization by acoustic microscopy

Abstract
We report the measurement of the acoustic material signature (AMS), amplitude and phase, on planar and nonplanar surfaces. The one-dimensional AMS is then used simultaneously with the scanning mode of the acoustic microscope to obtain the acoustic images of nonplanar surfaces. This technique is shown to be useful to test the quality of small spherical cavities used in the acoustic lenses fabrication, and also to characterize subsurface defects. This technique is based on the interpretation of fringe patterns appearing in the acoustic images.