Development of the correlation transfer equation of ultrasound-modulated multiply scattered light: a diagrammatic approach

In this paper, we develop a temporal correlation transfer equation (CTE) for ultrasound-modulated multiply scattered light. The equation can be used to obtain the temporal frequency spectrum of the optical intensity produced by a nonuniform ultrasound field in optically scattering media. Derivation of the CTE is based on the ladder diagram approximation of the Bethe-Salpeter equation. We expect the CTE to be applicable to a wide spectrum of conditions in the ultrasound-modulated optical tomography of soft biological tissues.