MODELING AND CORRECTING ILLUMINATION INHOMOGENEITY OVER MULTIPLE DLP ILLUMINATION INTENSITIES FOR BETTER FABRICATION ACCURACY

Within custom Digital Light Processing (DLP) systems, various small issues either in the optical assembly or with the DMD can lead to non-uniform illumination at the curing interface. This inhomogeneity leads to inaccurate dimensions of fabricated features over the full print area. To remedy this in our system, we have explored the relationship between LED output illumination, divided the illuminated area into a regional mesh, measured the light intensity and grayscale values over the mesh to obtain region-specific grayscale mask adjustments for illumination-leveling. This process involves producing grayscale mask by quantifiably balancing the light intensity values over build area and thus obtaining more uniform printed features. We compared the dimensional accuracy of features printed using full white pixel value images for 250µm features and those obtained using illumination-leveling grayscale processed images. Our results demonstrate the effectiveness of our method to obtain dimensionally accurate features, thanks to the achieved uniform illumination.