Design and Analysis of an Optical Target for FDTD Scattering Simulations by Shaping the CPML Absorbing Boundary Condition
Date Issued
2014
Date
2014
Author(s)
Clares, Sergio Cantero
Abstract
High scattering in most biological tissues limits the applicability of optical imaging techniques: Focusing depth and resolution depend not only on the absorption loss, but also on the successive scattering through the medium. Due to the complexity of the light propagation in tissue, accurate and robust simulations are necessary. In recent years, computations use the finite-difference time-domain (FDTD) method to exactly solve the electromagnetic field distribution in scattering through macroscopic media.
In this research, we propose implementing an optical target for FDTD light scattering simulations. To model light propagation through a macroscopic turbid medium to a target position, an absorber is required to eliminate impinging light. To construct a tool that absorbs incident light from all incident directions, we modify the convolutional perfectly matched layers (CPML) absorbing boundary condition into a localized, round-shaped optical target. The cylindrical target is then validated using two-dimensional FDTD simulations under omnidirectional light incidence.
Varying the different CPML parameters, we compute the absorption efficiency for its characterization in a wide range of applications, and we analyze the factors affecting its performance as a numerical optical target in macroscopic light scattering simulations. To demonstrate the applicability of the presented model, three examples are given in which we report: 1) Effective light elimination and isolation of electromagnetic fields within the problem region. 2) Detection of an ideal absorber within random media. And, 3) shaping the CPML absorbing boundary condition for reduction in computational time and memory resources of an FDTD simulation.
Subjects
光散射
時域有限差分法
光學模擬
光學靶
Type
thesis
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