Fig. 7, illustrates the waveforms obtained during measurements
for both direct and surface transmissions. Fig. 7a, shows the direct
transmission wave on the prism specimen using the 2 MHz transducers,
the P wave is very strong in the axial direction and its arrival
can be seen clearly. While, the R wave is confined on the surface
of the specimen and is not expected in direct transmission. In contrast,
Fig. 7b and c shows the surface transmission of the edge P