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Applied Optics

Applied Optics


  • Vol. 40, Iss. 21 — Jul. 20, 2001
  • pp: 3608–3613

Application of the small-angle approximation to ocean water types

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

Applied Optics, Vol. 40, Issue 21, pp. 3608-3613 (2001)

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The small-angle approximation to the radiative transport equation is applied to particle suspensions that emulate ocean water. A particle size distribution is constructed from polystyrene and glass spheres with the best available data for particle size distributions in the ocean. A volume scattering function is calculated from the Mie theory for the particles in water and in oil. The refractive-index ratios of particles in water and particles in oil are 1.19 and 1.01, respectively. The ratio 1.19 is comparable to minerals and nonliving diatoms in ocean water, and the ratio 1.01 is comparable to the lower limit for microbes in water. The point-spread functions are measured as a function of optical thickness for both water and oil mixtures and compared with the point-spread functions generated from the small-angle approximation. Our results show that, under conditions that emulate ocean water, the small-angle approximation is valid only for small optical thicknesses. Specifically, the approximation is valid only for optical thicknesses less than 3.

© 2001 Optical Society of America

OCIS Codes
(010.4450) Atmospheric and oceanic optics : Oceanic optics
(110.4100) Imaging systems : Modulation transfer function
(290.4020) Scattering : Mie theory
(290.4210) Scattering : Multiple scattering
(290.5820) Scattering : Scattering measurements
(290.7050) Scattering : Turbid media

Original Manuscript: October 26, 2000
Revised Manuscript: March 30, 2001
Published: July 20, 2001

Nancy L. Swanson, Barton D. Billard, Victor M. Gehman, and Theresa L. Gennaro, "Application of the small-angle approximation to ocean water types," Appl. Opt. 40, 3608-3613 (2001)

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