The first direct experimental observation of bulk-acoustic wave radiation f
rom a leaky surface-acoustic wave transducer, measured arriving at the back
side of the piezoceramic substrate, is reported. A scanning laser-interfero
metric probe is used to map the spatial distribution of the bulk-wave radia
tion patterns on the substrate bottom. The different energy-flow angles int
o the substrate are obtained as functions of frequency and used to identify
the corresponding bulk-wave modes arriving at the substrate bottom.