Fluidic Shaping and in-situ Measurement of Liquid Lenses in Microgravity

Abstract: In the absence of gravity, surface tension dominates over the behavior of liquids. While this often poses a challenge in adapting Earth-based technologies to space, it can also provide an opportunity for novel technologies that utilize its advantages. In particular, surface tension drives a liquid body to a constant-mean-curvature shape with extremely smooth surfaces, properties which are highly beneficial for optical components. We here present the design, implementation and analysis of parabolic flight experiments demonstrating the creation and in-situ measurement of optical lenses made entirely by shaping liquids in microgravity. We provide details of the two experimental systems designed to inject the precise amount of liquid within the short microgravity timeframe provided in a parabolic flight, while also measuring the resulting lens characteristics in real-time using both resolution target-imaging and a Shack-Hartmann wavefront sensing. We successfully created more than 20 liquid lenses during the flights. We also present video recordings of the process, from the lenses creation during microgravity and up until their collapse upon return to gravity. To the best of our knowledge, this is the first time that a purely liquid lens has been created in microgravity, which demonstrates the feasibility of creating and utilizing liquid-based optics in space.