Lighting Simulation for Visual Inspection System Using Patterned Area Illumination

We have developed methodologies for the detection of microdefects on painted surfaces and the evaluation of machined surface quality through the use of the patterned area illumination. The objective of this study is to optimize illumination for surface inspection of products by reproducing the illumination situation using the patterned area illumination. In this study, a ray tracing method, which is a computer graphics technique, was employed to reproduce a scenario in which a product surface is illuminated by the aforementioned patterned area illumination. In the conventional ray tracing method, the patterned area illumination is not taken into account. Accordingly, the surface to be inspected was postulated to be a mirror surface, and the illumination pattern was projected onto it in order to reproduce the reflection of the illumination pattern on the inspection surface. The developed simulation method enables several key optimizations. Firstly, it allows for the optimization of the illumination device by reproducing the inspection surface with a curved surface. Secondly, it enables the data augmentation of teacher data for machine learning for a versatile defect detector. Thirdly, it allows for the optimization of the circular pattern used to estimate the shape of micro defects. Finally, it enables the reproduction of pattern projection onto a machined surface for the evaluation of machining quality of the machined surface.