In-Situ Detection of Microplastics in Water Bodies through Ray Optics Simulation and Intensity Mapping

The growing prevalence of microplastics in aquatic environments has raised global concern, especially as these particles enter marine food webs and human biological systems. While various laboratory based techniques exist for microplastic detection, they often require complex instrumentation, intensive sample preparation, and are unsuitable for real-time field deployment. In response to this gap, we present a simulation based optical framework for the in-situ detection of microplastic pellets. The method relies on analyzing spatial intensity variations caused by the passage of collimated light through water containing suspended microplastics. Using ray tracing simulations, we demonstrate that refractive interactions between light and microplastic particles of size $\mathbf{1 0 0 - 5 0 0 0}$ microns produce characteristic intensity patterns on a detection surface, which can be used to infer particle presence and position. The system is designed to distinguish both increases and decreases in intensity caused by ray convergence and divergence. Our approach, developed and validated through ray-tracing simulations, and supported by Mie theory offers a cost effective, scalable, and realtime alternative to traditional detection techniques, and paves the way for the development of a fully deployable buoy system for continuous microplastic monitoring in natural water bodies.