Applying Grayscale Digital Masks and Defocusing Method to Digital Light Processing Stereolithography for Rapid Manufacture of Microlens Arrays

Grayscale digital masks and defocusing method were applied to digital light processing (DLP) stereolithography (SLA) 3D printing for the fabrication of various types of microlens arrays (MLAs) within 1 second. MLAs with high numerical aperture (NA) up to 0.98, MLAs with multiple focal lengths (21 ~ 199 μm) on a single substrate, MLAs with high fill factor of 77.98%, and aspherical MLAs were successfully demonstrated. Experiment results also clearly demonstrated that defocusing method efficiently reduced the surface roughness (S
a
) of the MLAs to 52 nm and led to an image resolution up to 45.3 lp/mm.