We present a new model of optical coherence tomography (OCT) taking into account multiple scattering. A theoretical analysis and experimental investigation reveals that in OCT, despite multiple scattering, the field backscattered from the sample is generally spatially coherent and that the resulting interference signal with the reference field is stationary relative to measurement time. On the basis of this result, we model an OCT signal as a sum of spatially coherent fields with random-phase arguments - constant during measurement time - caused by multiple scattering. We calculate the mean of such a random signal from classical results of statistical optics and a Monte Carlo simulation. OCT signals predicted by our model are in very good agreement with a depth scan measurement of a sample consisting of a mirror covered with an aqueous suspension of microspheres. We discuss other comprehensive OCT models based on the extended Huygens-Fresnel principle, which rest on the assumption of partially coherent interfering fields.
© 2005 Optical Society of America
(170.1650) Medical optics and biotechnology : Coherence imaging
(170.3880) Medical optics and biotechnology : Medical and biological imaging
(170.4500) Medical optics and biotechnology : Optical coherence tomography
(170.6900) Medical optics and biotechnology : Three-dimensional microscopy
(290.4210) Scattering : Multiple scattering
Boris Karamata, Markus Laubscher, Marcel Leutenegger, Stéphane Bourquin, Theo Lasser, and Patrick Lambelet, "Multiple scattering in optical coherence tomography. I. Investigation and modeling," J. Opt. Soc. Am. A 22, 1369-1379 (2005)