An adaptive direct slicing method based on tilted voxel of two-photon polymerization

Three-dimensional (3D) microstructures are fabricated with accumulated voxels layer-by-layer in two-photon polymerization (TPP). The overlap ratio and layer spacing between two neighboring layers both affects the surface accuracy and the processing efficiency. Presented in this paper is an adaptive direct slicing method that applies tilted voxels of TPP to satisfy contour change of 3D microstructure model with given overlap ratio. It extracted the contour line from a projected image of the original 3D microstructure model. The relative position of every two adjacent points on the contour line was used to reflect the interlayer spacing and calculate the tilted angle and overlap ratio of two neighboring voxels. The optimal interlayer spacing could be determined when the overlap ratio of tilted voxels of two neighboring layers exceeded a specified overlap ratio. Both axis-symmetry revolve and complex non-symmetrical microstructures were successfully sliced with higher efficiency and accuracy. The layer number reduces more than 30% compared with the adaptive direct slicing method based on vertical voxels by appropriate selection of overlap ratio and size of voxel. Quantitative analysis shows that the staircase errors decreased significantly with this adaptive direct slicing method. Unlike traditional slicing method, smaller overlap ratio and larger voxel benefits reducing layer number but has little effect on precision.