  We measure spectral properties of surface thermal fluctuations of liquids,
solids, complex fluids and biological matter using light scattering methods.
The random thermal fluctuations are delineated from random noise at sub-shot
noise levels. The principle behind this extraction, which is quite general and
is not limited to surface measurements, is explained. An optical lever is used
to measure the spectrum of fluctuations in the inclinations of surfaces down to
$\sim 10^{-17}\rm rad^2/Hz$ at $1\sim10 \mu$W optical intensity, corresponding
to $\sim 10^{-29} \rm m^2/\rm Hz$ in the vertical displacement, in the
frequency range $1{\rm}\rm kHz\sim10 MHz$. The dynamical evolution of the
surface properties is also investigated. The measurement requires only a short
amount of time and is essentially passive, so that it can be applied to a wide
variety of surfaces.
