Effect of Numerical Dispersion in FDTD Simulations of Light Scattering from Photoreceptors

Recently, the FDTD method was used to investigate the optical functional response of retinal photoreceptors. Light scattering patterns of the cells were simulated under various hypothetical states to determine the physiological processes that are most likely responsible for the experimentally observed signals. An FDTD model of a photoreceptor cell spans several wavelengths, therefore, the numerical dispersion, inherent in FDTD algorithms, will introduce significant phase errors in the simulation results. These phase errors can lead to erroneous predictions, especially for narrow band light stimulus. Currently, the qualitative and quantitive effects of numerical dispersion on light scattering computations are still unknown. In this paper, an analysis of the numerical dispersion errors in the near and far scattered fields is performed. The analysis provides decision guidelines for selecting enough computational resources to obtain the light scattering patterns with acceptable margin of errors.