This paper discusses theoretical aspects of the V(z) response of the scanning acoustic microscope (s. a. m. ) when used to examine specimens with lateral discontinuities. The problem is introduced in terms of a simple ray model to establish a physical picture of the processes involved. At an interface between media with different elastic properties, the contrast is affected not only by the scattering properties of the boundary but also by the very fact that surface waves must propagate in media with different elastic properties. This effect can provide a powerful contrast mechanism which enables one to understand the light to dark contrast reversals often observed at grain boundaries in polycrystalline specimens at different values of defocus.
|Number of pages||23|
|Journal||Proceedings of The Royal Society of London, Series A: Mathematical and Physical Sciences|
|Publication status||Published - 9 Sep 1985|
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