Systematic comparison of the discrete dipole approximation and the finite difference time domain method for large dielectric scatterers

Jun Q. Lu,Maxim A. Yurkin,R. S. Brock,Alfons G. Hoekstra

doi:10.1364/oe.15.017902

Abstract

We compare the discrete dipole approximation (DDA) and the finite difference time domain (FDTD) method for simulating light scattering of spheres in a range of size parameters x up to 80 and refractive indices m up to 2. Using parallel implementations of both methods, we require them to reach a certain accuracy goal for scattering quantities and then compare their performance. We show that relative performance sharply depends on m. The DDA is faster for smaller m, while the FDTD for larger values of m. The break-even point lies at m = 1.4. We also compare the performance of both methods for a few particular biological cells, resulting in the same conclusions as for optically soft spheres.

Highlights

The discrete dipole approximation (DDA) [1,2] and the finite difference time domain method (FDTD) [3,4] are two of the most popular methods to simulate light scattering of arbitrarily shaped inhomogeneous particles
As an intermediate case between homogeneous spheres and real biological cells, we consider a coated sphere model consisting of two concentric spheres, which is an approximation for the B-cell precursor (BCP) shape described above
Values of dpl cannot be directly compared between both methods because the typical values for the DDA [1] are twice as small as for the FDTD [4]

Summary

Introduction

The discrete dipole approximation (DDA) [1,2] and the finite difference time domain method (FDTD) [3,4] are two of the most popular methods to simulate light scattering of arbitrarily shaped inhomogeneous particles. These methods have a very similar region of applicability; they are rarely used together. We focus on particles with negligible absorption, e.g. biological particles This covers a broad range of slightly absorbing materials, e.g. water and ice, because performance of both methods do not depend significantly on small imaginary part of the refractive index.

DDA and FDTD implementations

Test objects

Results for spheres

Sample applications to biological cells

Conclusion