Wavelength-dependent scattering in spectroscopic optical coherence tomography.

The particle sizing capabilities of light scattering spectroscopy (LSS) and the spatial localization of optical coherence tomography (OCT) are brought together in a new modality known as scattering-mode spectroscopic OCT. An analysis is presented of the spectral dependence of the light collected in spectro-scopic OCT for samples comprised of spherical particles. Many factors are considered including the effects of scatterer size, interference between the fields scattered from closely adjacent scatterers, and the numerical aperture of the OCT system. The modulation of the spectrum of the incident light by scattering of a plane wave from a single sphere is a good indicator of particle size and composition. However, it is shown in this work that the sharp focusing of fields causes the spectral signature to shift and the presence of multiple scatterers has dramatic modulation effects on the spectra. Approaches for accurately matching physical structure with the observed signals under various conditions are discussed.