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Journal of the Optical Society of America A

Journal of the Optical Society of America A


  • Vol. 18, Iss. 2 — Feb. 1, 2001
  • pp: 385–391

Limits of the small-angle approximation to the radiative transport equation

Nancy L. Swanson, Victor M. Gehman, Barton D. Billard, and Theresa L. Gennaro  »View Author Affiliations

JOSA A, Vol. 18, Issue 2, pp. 385-391 (2001)

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The small-angle approximation to the radiative transport equation is used extensively in imaging models in which the transport medium is optically thick. The small-angle approximation is generally considered valid when the particles are very large compared with the wavelength, when the refractive-index ratio of the particle to the medium is close to 1, and when the optical thickness is not too large. We report results showing the limits of the validity of the small-angle approximation as a function of particle size and concentration for a particle-to-medium fixed refractive-index ratio of 1.196. This refractive-index ratio is comparable with that of minerals or diatoms suspended in water.

© 2001 Optical Society of America

OCIS Codes
(110.4850) Imaging systems : Optical transfer functions
(290.4020) Scattering : Mie theory
(290.4210) Scattering : Multiple scattering
(290.5820) Scattering : Scattering measurements
(290.5850) Scattering : Scattering, particles
(290.7050) Scattering : Turbid media

Original Manuscript: February 14, 2000
Revised Manuscript: August 21, 2000
Manuscript Accepted: August 21, 2000
Published: February 1, 2001

Nancy L. Swanson, Victor M. Gehman, Barton D. Billard, and Theresa L. Gennaro, "Limits of the small-angle approximation to the radiative transport equation," J. Opt. Soc. Am. A 18, 385-391 (2001)

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