Direct measurement of the spatial distribution of light intensity in a scattering medium

A direct nonperturbative measurement of the spatial distribution of the lig ht intensity in a strongly scattering medium is performed using an optoacou stic method. It is shown that near a surface the intensity can be five time s greater than the incident intensity, and the absolute maximum of the inte nsity is observed at a depth l(1-R)(1-4.0R) determined by the photon transp ort mean free path l and the effective light reflection coefficient R of th e boundary separating the scattering and external media. (C) 1999 American Institute of Physics. [S0021-3640(99)00615-5].