Rapid fabrication of height-tunable high-aspect-ratio voxels by tailored Bessel beams

We present a fast method to produce height-controllable high-aspect-ratio (HAR) voxels in the two-photon polymerization process. By loading complex-amplitude encoded holograms onto a phase-only spatial light modulator (SLM), precise control over the axial intensity profile of a Bessel beam is achieved, enabling the fabrication of height-tunable HAR voxels in a single exposure without mechanical axial motion. The voxel height can be adjusted independently and continuously over a range of 15 μm while maintaining the constant lateral size of 1.3 μm simply by switching tailored Bessel beam holograms. As demonstrated, microneedle arrays and hollow circular and polygonal microtubes with graded heights were fabricated.