Photon diffusion coefficient in scattering and absorbing media.
We present a unified derivation of the photon diffusion coefficient for both steady-state and time-dependent transport in disordered absorbing media. The derivation is based on a modal analysis of the time-dependent radiative transfer equation. This approach confirms that the dynamic diffusion coefficient is given by the random-walk result D = cl(*)/3, where l(*) is the transport mean free path and c is the energy velocity, independent of the level of absorption. It also shows that the diffusion coefficient for steady-state transport, often used in biomedical optics, depends on absorption, in agreement with recent theoretical and experimental works. These two results resolve a recurrent controversy in light propagation and imaging in scattering media.
Pierrat
Romain
R
Laboratoire d'Energétique Moléculaire et Marcoscopique, Combustion, Ecole Centrale Paris, Châtenay-Malabry, France.
Greffet
Jean-Jacques
JJ
Carminati
Rémi
R
D000042:Absorption; D000465:Algorithms; D003198:Computer Simulation; D004058:Diffusion; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D016247:Information Storage and Retrieval / Q000379:methods*; D008954:Models, Biological; D009391:Nephelometry and Turbidimetry / Q000379:methods*; D017785:Photons; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D012542:Scattering, Radiation; D041622:Tomography, Optical / Q000379:methods*