Numerical analysis of a path-length-resolved spectrum of time-varying scattered light field

The path-length-resolved power spectrum of a time-varying scattered light field measured by a time-of-flight method or low-coherence interferometry is evaluated by a new numerical simulation algorithm. The path-length-resolved power spectrum is theoretically derived by combining diffusing-wave-spectroscopy theory and radiative-transfer theory. The proposed algorithm, using the Monte Carlo method, is used to determine the scattering configurations and numerically calculate the power spectrum. The path-length distribution, path-length-dependent scattering order distribution, and path-length-resolved power spectrum are demonstrated numerically over all scattering orders. The resultant power spectra agree with experimental results measured by the low-coherence-dynamic-light-scattering method.