Simulating ceramic-filled vat photopolymerization resins using Monte Carlo ray tracing

Photocurable ceramic suspensions used in vat photopolymerization (VP) to produce composite and ceramic parts suffer from reduced resolution due to light scattering by the particles. When irradiated, the scattered light causes a redistribution of the UV intensity, resulting in a reduction in cure depth and an increase in cure width. To predict the resulting exposure distribution and cure profile shape of ceramic-loaded resins, the authors develop a Monte Carlo ray-tracing (MCRT) simulation to predict light scattering and absorption of UV energy in particle-filled resins. The simulation incorporates volume-dependent light scattering physics of polydisperse particle sizes to accurately represent the scattering behavior of filled resins. Additionally, the simulation uses only experimentally acquired parameters, including refractive index, particle size distribution, the spatial intensity distribution of the light source, and critical exposure to cure to predict the photocured shape. With these parameters, the authors simulate cure profiles of a zinc oxide-filled polyester acrylate resin, which has a high refractive index of 2.2. Printed and simulated cure profiles are compared across varying ZnO loadings (1-5 vol%) to validate the simulation. The simulation demonstrates a high degree of accuracy in predicting the experimental cure profile shape with all cure depth predictions within 10% (20 µm) and cure widths within 30% (15 µm).