  There is currently a renewed interest in the development of experimental
methods to achieve the elastic characterization of thin films, multilayers and
acoustic resonators operating in the GHz range of frequencies. The
potentialities of surface Brillouin light scattering (surf-BLS) for this aim
are reviewed in this paper, addressing the various situations that may occur
for the different types of structures. In particular, the experimental
methodology and the amount of information that can be obtained depending on the
transparency or opacity of the film material, as well as on the ratio between
the film thickness and the light wavelength, are discussed. A generalization to
the case of multilayered samples is also provided, together with an outlook on
the capability of the recently developed micro-focused scanning version of the
surf-BLS technique, which opens new opportunities for the imaging of the
spatial profile of the acoustic field in acoustic resonators and in
artificially patterned metamaterials, such as phononic crystals.
