title: Validity conditions for the radiative transfer equation.
abstract: We compare the radiative transfer equation for media with constant refractive index with the radiative transfer equation for media with spatially varying refractive indices [J. Opt. A Pure App. Opt. 1, L1 (1999)] and obtain approximate conditions under which the former equation is accurate for modeling light propagation in scattering media with spatially varying refractive indices. These conditions impose restrictions on the variations of the refractive index, the gradient of the refractive index, the divergence of the rays, the frequency of modulation, and the widths of light pulses, which are related to the mean refractive index, the absorption coefficient, and the reduced scattering coefficient of the medium. Each condition is geometrically interpreted. Some implications of the results are discussed.
authors: Centro de Neurociencias de Cuba, Apartado Postal 6412, C. P. 10600, La Habana, Cuba. marti@cneuro.edu.cu
authors: Luis
authors: L
authors: Martí-López
authors: Jorge
authors: J
authors: Bouza-Domínguez
authors: Jeremy C
authors: JC
authors: Hebden
authors: Simon R
authors: SR
authors: Arridge
authors: René A
authors: RA
authors: Martínez-Celorio
mesh_terms: D008027:Light; D008962:Models, Theoretical; D012031:Refractometry; D012542:Scattering, Radiation; D041622:Tomography, Optical