The study and applications of light scattering have been enormously simplified and extended with the availability of reliable laser sources over a wide range of wavelengths. The central component in light scattered from solid materials has been the subject of investigation. With their transparency and ease of sample preparation, optical materials were obvious and subjects for light scattering studies. The subject of light scattering is of considerable antiquity with discussion of the scattering from discrete particles by Tyndall and Lord Rayleigh. An enormous literature, both theoretical and experimental, exists that describes the range of scattering, relaxation and dispersion mechanisms manifest in light scattering from liquids. Light scattering from liquid helium in several domains has been a fruitful subject of investigation. Fabry–Perot interferometers have been extensively applied to light scattering from solids in many and various domains. Brillouin light scattering from the surface of metals—Hg and liquid Ga—was reported by J. G.Dil and J. K. Brody.