The microlens array has attracted significant attention with the increasing demand for optoelectronic miniaturization. It has become an important micro-optic device widely used in compact imaging, sensing, optical communication, and other applications. Microlens arrays are typically made up of multiple micron-sized lenses with optical surface smoothness and superior uniformity, which increases the need for machining precision.
Researchers have proposed combining oscillation-assisted digital light processing (DLP) 3D printing with grayscale UV exposure. The combination produces ultrafast and flexible microlens array fabrication with optical surface smoothness.
It is difficult to 3D print small geometries (miniaturization) with optical surface smoothness. The researchers used computationally designed grayscale patterns to create microlens profiles in a single UV exposure, eliminating the staircase effect found in traditional layer-by-layer 3D printing. The projection lens oscillation removes the jagged surface caused by the gaps between discrete pixels.
Scanning electron and atomic force microscopy, morphology characterizations show that the integration of projection lens oscillation significantly smoothens the lens surface and reduces surface roughness from 200 nm to about 1 nm. In addition to surface roughness, lens profile significantly impacts optical performance. The researchers created a theoretical model to describe the photopolymerization process and predict the lens profile to help with grayscale design for microlens array fabrication.