Abstract: The polarization state of light in the ocean can beused to enhance visibility. The consequences ofscattering from nonspherically-symmetric particles onlight propagation and visibility in the ocean wasinvestigated. To calculate scattering from nonsphericalmarine microorganisms, it is usually necessary toresort to approximate methods. One promisingapproximation is the coupled-dipole approach in whichan arbitrarily-shaped object is divided into a numberof identical elements arranged on a cubic lattice. Eachelement is treated as a spherical, dipolar oscillatorwith its polarizability specified by the real andimaginary parts of the index of refraction.Interactions between dipoles are included bydetermining the field at a particular dipole due to theincident field and the fields induced by the otherdipole oscillators. The scattered field is then the sumof the fields due to each oscillator. Thecoupled-dipole method is promising because, inprinciple, an organism of any shape can be modeled, andall 16 elements of the scattering matrix calculated.This approach has been applied to calculate scatteringfrom spherical particles to verify the limits of theapproximation, and from other shapes to investigate theeffects of nonsphericity and chirality on scattering.In particular, all 16 Mueller matrix elements for thescattering were calculated from a finite cylinder, asingle- strand helix, 14-strand helix, and ensembles ofthese particles. The effects of pitch, size,wavelength, and complex index of refraction wereinvestigated. The results provide insights into themagnitude and type of depolarization effects associatedwith various marine microorganisms containing thesestructures. !8
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