Dispensing of microlenses under adjustable gravity

Lenses are essential components in photonic systems to enable compact and high-performance optical applications. Although various lens fabrication methods exist, the influence of gravity on these processes has remained understudied due to limited access to variable gravity environments. We leverage the Einstein-Elevator, the first third-generation drop tower in operation, to investigate the effects of gravity on the fabrication of polymer-based microlenses, which are produced by jet dispensing of sessile photopolymer droplets onto a glass substrate and subsequent ultraviolet curing. Systematic experiments were conducted under six different gravitational conditions (0, 0.17, 0.38, 0.6, 0.8, and 1 g) [g: Earth's gravity (1 g=9.81 m/s2). It is written in italics to avoid confusion with the unit gram ("g,"not italicized)]. The manufactured lenses were analyzed for morphological parameters including curvature, height, diameter, and contact angle. The findings reveal that gravity has minimal effect on the morphology of small lenses, but there is evidence that larger lenses undergo observable changes under reduced gravity. It is possible to achieve tailored droplet morphologies by varying gravity. These results show that gravity influences manufacturing processes and that gravity is an essential parameter, which is not only relevant for future manufacturing processes in space.