Optical cross-sectional imaging with pulse ultrasound wave assistance

We have developed an optical cross-sectional imaging method for turbid media with the aid of a pulse ultrasound wave. Observation of deep regions in turbid media, such as tissue samples, is difficult owing to the rapid dispersion of an incoming laser beam by scattering. A pulse ultrasound wave, which is less scattered in tissues, can indicate the measuring point on the basis of the change of the optical scattering properties in a localized region. A depth-resolving capability can be achieved from the time-dependent measurement of the scattered-light intensity as the pulse ultrasound wave propagates in the sample. We verified the method by observing absorptive objects embedded in silicone rubber and by obtaining the cross-sectional image of an absorbing object surrounded by a strong scattering medium.