LIMITATIONS OF DIFFUSION-APPROXIMATION IN DESCRIBING FEMTOSECOND LASER TRANSILLUMINATION OF HIGHLY SCATTERING MEDIA OF BIOLOGICAL SIGNIFICANCE

Ultrafast laser pulses transmitted through highly scattering media hav e been detected by a streak camera. Experimental data, showing the tem poral spread of the ultrafast pulse during the transmission through hi ghly scattering media with various optical discontinuities, have been approximated using the diffusion theory. This analysis explicitly show s how the overall optical parameters of the sample (mu(a),mu(s)') are influenced by the presence of the discontinuities and proposes the ful l width at half-maximum as an experimental index of the transition bet ween ballistic and diffusive photon transport. (C) 1995 American Insti tute of Physics.