UC Irvine

We have investigated the accuracy of the frequency-domain, diffusion equation Green's function in modeling optical signals in turbid media. Our optical measurements were conducted in strongly scattering media having absorption coefficients in the range 0.035-0.14 cm-1 and reduced scattering coefficients in the range 5-22 cm-1. The optical signal was both delivered to and collected from the sample by means of optical fibers. We have verified that the r-independent factor in the Green's function does not agree with the experimental data. This discrepancy shows that the photons launched in the medium by an optical fiber cannot be modeled by a point source located at a fixed position. These results have no influence on multi-distance measurement protocols (which only employ the r-dependent part of the solution), while they must be considered when calibration measurements on a known sample are performed.