VOLUMETRIC ADDITIVE MANUFACTURING WITH 3D POINT CLOUD PROJECTION AND SINGLE-PHOTON NONLINEAR POLYMERIZATION

Volumetric additive manufacturing allows simultaneously patterning an entire 3D object by irradiating a photosensitive resin with UV to near-infrared light. An obvious advantage of volumetric additive manufacturing is its capability to construct 3D objects without support structures. Also, volumetric additive manufacturing allows fast 3D fabrication compared with layer-by-layer stacking type 3D fabrication. However, demonstrated volumetric additive manufacturing, such as computed axial lithography, has a resolution limited to similar to 50 mu m. This study shows that enhanced 3D point cloud projection and single-photon nonlinear polymerization can be used as a new volumetric additive manufacturing method to achieve deep micron-level resolution. The enhanced 3D point cloud projection is achieved with a phase-modulated spatial light modulator (SLM) that can precisely control the diffraction of mini-rays used to generate voxels in the 3D point cloud projection. Consistent deep micron level voxel sizes with minimum side lobes were achieved by randomizing the azimuth and polar angles of the mini-rays from the SLM to diminish unwanted constructive interferences of the mini-rays except at the designed voxel locations. High spatial resolution volumetric additive manufacturing can be achieved by delivering the compressed 3D point clouds from the enhanced 3D point cloud projection with shapes mimicking the desired 3D structures in photopolymers supporting single-photon nonlinear polymerization (e.g., SU-8 with dissolved oxygen as inhibitors). Numerical algorithms for generating 3D point clouds with the enhanced 3D point cloud projection having deep micron resolution and preliminary results of generating simple 3D geometries through the new 3D point cloud projection and single-photon nonlinear polymerization are presented in this study.