In the past decade, considerable progress has been made in the development of Brillouin scattering (BS) as a technique for the nondestructive characterization of materials. With the advent of high resolution and high contrast multipass tandem Fabry-Perot interferometry [1], BS has been applied to the measurement of the near-surface elastic properties of opaque materials [2], thin supported films [3] and interfaces [4], making use of various guided and localized acoustic modes including Rayleigh waves, pseudo-surface acoustic waves (p-SAW), Sezawa waves and Stoneley waves. By identifying the presence of particular acoustic modes in BS spectra, and comparing these with calculation, one can extract information pertaining to the physical properties of the system.