Fig. 2.
2D Monte Carlo simulation of light propagation inside a scattering slab whose dimensions were x=160 L and z= 40 L . Initially, a broad (a–d) or a narrow (e–h) light beam was normally incident at the origin of the coordinates. In each panel, the top plot shows the trajectories while the bottom plot shows the photon density distribution(s) along the optical axis (total density shown in black). a & e, diffusive trajectories of S(fs) propagating through the slab: some (shown in green) reach the phase-conjugate mirror and the others (shown in blue) do not. b & f, trajectories of S* ( fs ) propagating back through the slab and converging to the incident point. c & g, trajectories of S( f ) (shown in blue) and the ultrasonically encoded component S(f+) (shown in green) inside the slab. d & h, trajectories of S*(f+) converging back to the ultrasonic focus (shown in green) then back to the incident point (shown in magenta). The black circles in the middle of the slab denote the ultrasonic focus. UE: Ultrasonically Encoded light.