3D Printing of Optical Lenses Assisted by Precision Spin Coating

Abstract

Though 3D printing shows potential in fabricating complex optical components rapidly, its poor surface quality and dimensional accuracy render it unqualified for industrial optics applications. The layer steps in the building direction and the pixelated steps on each layer's contour result in inevitable microscale defects on the 3D-printed surface, far away from the nanoscale roughness required for optics. This paper reports a customized vat photopolymerization-based lens printing process, integrating unfocused image projection and precision spin coating to solve lateral and vertical stair-stepping defects. A precision aspherical lens with less than 1 nm surface roughness and 1 µm profile accuracy is demonstrated. The 3D-printed convex lens achieves a maximum MTF resolution of 347.7 lp mm−1. A mathematical model is established to predict and control the spin coating process on 3D-printed surfaces precisely. Leveraging this low-cost yet highly robust and repeatable 3D printing process, the precision fabrication of multi-scale spherical, aspherical, and axicon lenses are showcased with sizes ranging from 3 to 70 mm using high clear photocuring resins. Additionally, molds are also printed to form multi-scale PDMS-based lenses.