Real-time interface monitoring and active focusing for high-fidelity multi-material DLP 3D printing

Top-down digital light processing (DLP) 3D printing is a promising approach for high-resolution and multi-material fabrication. However, the unconstrained resin surface often leads to curing outside the focal plane during the printing process, resulting in significant losses in manufacturing accuracy. To address this defocusing issue, we propose an improved top-down DLP 3D printing method that enables real-time calibration of the resin level, ensuring each layer is printed precisely on the focal plane. This approach reduces the deviation between the curing plane and the focal plane from hundreds of microns to just a few microns, significantly enhancing printing resolution and surface finish. Additionally, the method allows for the fabrication of multi-material objects with gradual interfaces in a single vat, improving bonding strength between different materials. Moreover, by controlling the resin level, the proposed technique facilitates material switching between multiple vats while maintaining a constant curing plane, enabling the creation of high-fidelity multi-material structures. This innovative strategy advances the field of DLP 3D printing by offering a rapid, precise, and versatile solution for high-resolution and multi-material fabrication.