Lateral resolution enhancement in low-cost DLP 3D printing via integrated optical focusing and collimation

Digital light processing (DLP)-based additive manufacturing systems offer high printing speeds; however, their resolution is inherently limited in low-cost configurations due to projector pixel size, optical divergence, and angular light incidence on the photopolymer surface. In this study, a compact optical module consisting of focusing and collimation lenses was integrated between a commercial DLP projector and the photopolymer vat to address these limitations. The proposed system concentrates the projected light onto a reduced exposure area and enforces near-normal light incidence, improving voxel definition and suppressing angular curing artifacts. Benchmark geometries were fabricated with and without the optical module using a single daylight-sensitive photopolymer resin. The results show that the effective pixel size was reduced from approximately 165–170 μm to 43–46 μm. In addition, the increased irradiance enabled a reduction in layer exposure time from 2,500 to 100 ms, resulting in an overall printing time reduction of about 30%. Although the optical configuration limits the build area, it provides a purely physical and effective alternative to software-based super-resolution approaches for low-cost DLP systems.