Turbid acousto-optics and its potential for biomedical applications

Continuous-wave ultrasonic modulation of scattered laser light has been used to image objects in tissue-simulating turbid media for the first time. The modulated laser light collected by a photomultiplier tube reflected the local mechanical and optical properties in the modulation zone. Buried objects in 5-cm thick tissue phantoms were imaged with millimeter resolution by scanning and detecting alterations of the ultrasound-modulated optical signal. The tissue phantoms had the following optical properties: absorption coefficient /spl mu//sub a/=0.1 cm/sup -1/, reduced scattering coefficient /spl mu//sub s/'=10 cm/sup -1/, which are comparable with those of biological tissues in the visible and near IR range. This technique is merely a representation of a much broader discipline coined turbid acousto-optics, which means acousto-optics in turbid media.