Numerical Study of Light Scattering in Plant Leaves via Finite-Difference Time-Domain Simulations

Scattering and absorption of light within plant leaves are significantly influenced not only by photosynthetic activity but also by internal leaf structures. Although hyperspectral imaging is widely used to monitor plant health, it essentially functions as a black-box approach that lacks a physics-based assessment of internal leaf structures, highlighting the need for more accurate light scattering models. Traditional studies on light scattering in plant leaves have largely relied on ray-tracing and vector radiative transfer methods, which are more suitable for high-frequency regimes and weak diffraction or scattering phenomena. In this study, we present a novel approach that departs from conventional methodologies by employing the Finite-Difference Time-Domain (FDTD) algorithm and simulations, enabling full-wave, first-principles modeling of light scattering and absorption. Based on X-ray imaging data, we model and mesh the internal anatomical structures of plant leaves—including the cuticle, epidermis, palisade and spongy mesophyll, vascular bundle, and stomata—and assign appropriate (complex) refractive indices to each tissue layer. This framework allows for the numerical calculation of reflectance and transmittance across a broad range of visible wavelengths under normal light incidence. The proposed methodology offers a physically grounded modeling strategy for assessing plant health through light scattering analysis and is expected to be particularly effective in capturing structural degeneration within leaves caused by both pathogenic and non-pathogenic factors.