Fiber dispersion in time domain measurements compromising the accuracy of determination of optical properties of strongly scattering media

Limitations in the accuracy of measurements of optical properties (absorption and scattering coefficients) of strongly scattering media that are due to temporal dispersion inside the detection fibers of a time-of-flight setup were investigated for a tissue-like phantom. It is shown that the absorption and reduced scattering coefficients may be overestimated by up to 90% (depending on length and numerical aperture of the fibers) if the instrumental response measurements for the setup are performed by direct illumination of the tip of the detection fibers with collimated short laser pulses. However, the accuracy can be improved significantly if a thin layer of scattering media is used in front of the detection fibers during the response measurements. The relevance of the investigated dispersion effects is discussed with respect to frequency-domain measurements as well.