Light Scattering in the Ocean and in Biological Tissues
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In the first part of this dissertation, we simulate the underwater polarized light field. A three-dimensional backward Monte Carlo code is developed to simulate light scattering for an atmosphere-ocean system. In this model, we send photons from the detector and propagate them toward the source, which allows us to calculate the effective Mueller Matrix of the medium. The 3D vector radiation field can be calculated with dynamic interface, complex boundary conditions, as well as the complex ocean objects included in the system. The polarizer imaging is first modeled when polarizers are stuck on the surface of a piece of mirror and put in the open ocean to study the light polarizations in the ocean water. The effects of observation distance and viewing angle on the radiance, the degree of polarization, as well as the angle of polarization are studied systematically. Then we use a simple tank model, where several spheres of different sizes and different scattering properties were placed, to simulate what a marine organism can see under the water. Images based on four different Stokes components are obtained for a variety of underwater circumstances. In the second part, we study the effect of both coherent and incoherent beams on both forward and multiple scattering of particulate media in biological tissues. The phase shift of a single particle in the forward direction is calculated using the anomalous diffraction method; the influence of particle size distributions, particle shapes, and particle orientations on the forward coherent peaks is studied for an ensemble of particles. In particular, we demonstrate the forward coherent scattering, as well as multiple scattering properties in detail for the chromatophore cell in cephalopods and the human blood system. Additionally, Mueller matrix components with partially coherent or even non-coherent incident beams are investigated in order to study the effect of coherence length on the forward coherent scattering and multiple scattering.
Chen, Dayou (2016). Light Scattering in the Ocean and in Biological Tissues. Doctoral dissertation, Texas A & M University. Available electronically from