Acousto-optic effect in random media

We consider the acousto-optic effect in a random medium. We derive the radiative transport equations that describe the propagation of multiply scattered light in a medium whose dielectric permittivity is modulated by an acoustic wave. Using this result, we present an analysis of the sensitivity of an acousto-optic measurement to the presence of a small absorbing inhomogeneity.

Figure 1

Illustration of the acousto-optic effect in a random medium.

Figure 2

Contour plot of $U_{11}$ in the $y=0$ plane.

Figure 3

Illustration of the geometry of the experiment. The source and detector are located on the $z=0$ plane and the absorber is located at a depth $z=z_1$.

Figure 4

Shown on top is $\mathrm{\Delta }$ as a function of the depth $z_1$ of the absorber for a contrast $\delta {\mu }_a/{\overline{\mu }}_a=3$. On the bottom is $\mathrm{\Delta }$ as a function of $\delta {\mu }_a/{\overline{\mu }}_a$ for $z_1=1\mathrm{cm}$. Parallel and perpendicular orientations of the acoustic wave vector $\mathbf{Q}$ are shown.