Fig. 1.

PSTD simulation of the TRUE technique. In the TRUE technique, a virtual light source (yellow arrow) is formed inside the scattering medium where the incident light (yellow dashed lines) and incident ultrasound (purple dashed lines) overlaps and light is frequency-shifted by the ultrasound pulse. Light reaching the OPC region (blue shaded-area) is phase-conjugated and back-propagates towards the virtual source. The PSTD simulation region is surrounded by an APML absorbing boundary condition (pink shaded area) to model an isolated system.