Automated Grayscale Modulation to Enhance Digital Light Processing Fabrication Accuracy by Correcting Nonuniform Illumination

Abstract

In this study, we addressed the challenge of nonuniform illumination in custom digital light processing (DLP) systems, often caused by imperfections in the digital micromirror device (DMD) or misalignments in the optical assembly. These issues lead to dimensional inconsistencies across the fabrication area. To overcome this, we developed an automated system for generating a “grayscale” mask that compensates for nonuniform illumination. This system serves as a preprinting calibration procedure, enhancing the precision of three-dimensional (3D) printed features. Our approach involves dividing the fabrication area into a mesh grid where in situ light intensities are measured. The system then calculates and acquires grayscale values that correspond to the minimum light intensity, thereby creating a grayscale mask that levels light distribution across the printing area. Additionally, we outline a method to generate grayscale masks for various light-emitting diode (LED) excitation powers (LEPs) based on initial data from three predefined powers. We evaluated the effectiveness of this method by comparing features printed with standard “full white” images to those adjusted with our grayscale-modulated images. The results show significant enhancements in both uniformity and dimensional accuracy, confirming the efficacy of our approach. This study demonstrates the potential of grayscale modulation to resolve illumination issue in DLP manufacturing to ensure higher precision in printed features.