Fiber-optic detection of ultrashort laser pulses diffusely reflected from Intralipid skin phantom:Effect of numerical aperture and scattering anisotropy

In this paper, simulations by Monte Carlo method are applied to reveal the effect of numerical aperture (NA) of a detector (backward registration) and scattering anisotropy of a sample (g) on the probing depth of the sample. Correlation between temporal and depth-resolved detection is investigated as a function of the considered characteristics, NA and g. Decrease of the numerical aperture of the detector or increase of the scattering anisotropy of the sample lead to probing of deeper depths and larger region around. These depths correspond to the maximal numbers of the detected photons measured with time-resolved registration. The better correlation comes from the use of fibers with smaller apertures and media with strong forwards scattering (high value of anisotropy factor).