The Effects of Surface Roughness on Subsurface Defect Detection using Acoustic Microscopy

A schematic diagram of the acoustic microscope’s operation is shown in Fig. 1. An efficient, focused transducer was excited with a tone burst in order to interrogate the sample of interest. It was also used as the receiving transducer in order to detect the echo from the surface. The transducer receives the reflected signal which is rectified and filtered to give a signal proportional to the amplitude of the returned signal. The transducer is mechanically scanned in a raster style in order to create a two-dimensional acoustic image. This image is then displayed on a high resolution color monitor using various pseudo-color and grey-level color schemes