Fluidic Assisted Fabrication of Elastomer Optical Lenses Using Capillarity
Traditional methods of optical glass-based lens fabrication require subtractive manufacturing, which leads to high loss of material and long cycle time. With polymeric lenses, however, additive manufacturing methods work very well and have advantages of shorter processing times, negligible material loss and reduced costs. Unfortunately, up to now, only small-sized polymeric lenses with plano-convex shape can be fabricated. The work described in this thesis proposes a fast, repeatable, and cost effective method of producing bi-convex and plano-convex polymeric lenses utilizing the capillarity effect at liquid-liquid interface. It was demonstrated that, by controlling the material properties, such as density, viscosity and interfacial tension, polymeric lenses with the desired magnifying power can be fabricated over a large size range. To explore the underlying dynamics of the multiphase interactions, numerical models were developed using the phase-field model. The dynamics of the lens forming process and the equilibrium shape of the polymeric lens can be captured by the numerical models. An analytical relationship between the lens volume, radius and thickness was also obtained by utilizing the Young-Laplace and force balance equations. The numerical and analytical predictions were validated by experimental results obtained using Polydimethylsiloxane (PDMS) as the lens material at the oil-water interface. It is expected that the quantitative understanding developed in this work will pave the way for future cost-effective manufacturing of polymeric optical lenses on a commercial scale.