Research Highlights

We report a novel diffuse optical spectroscopy probe design for determining optical properties of superficial volumes of turbid samples. The fiber based probe employs a highly scattering layer placed in contact with the sample of interest. This layer diffuses photons from a collimated light source before they enter the sample, and provides a basis for describing light transport in superficial media using the diffusion approximation. In this letter, we demonstrate the performance of this modified two-layer diffusion model in comparison to Monte Carlo simulations. A set of experiments that demonstrate the feasibility of this method in turbid tissue phantoms is also presented. Optical properties deduced using this approach are in good agreement with those derived using a benchmark method for determining optical properties. The average interrogation depth of the probe design investigated here is estimated to be less than 1mm.

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Figure 1. (a) Typical DOS and (b) modified two-layer measurement geometries.

Figure 2. (a) Amplitude and (b) phase versus source modulation frequencies generated from MTL diffusion model (solid line) and Monte Carlo simulation (asterisks). See text for parameters used. Monte Carlo simulation results shown in squares were generated using a layered sample composed of a 2mm thick layer (µ_a2=0.04/mm, µ_s'2=0.7/mm) with underlying semi-infinite layer (µ_a3=0.08/mm, µ_s'3=1.4/mm ).

References

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