Research on fabrication of fluidic lens array with variable focal length

Abstract

The research was mostly focused on the fabrication of lens array whose individual lens is able to adjust its focal length, thus most parts of this manuscript are spent for the description of auto-focus (AF) mechanism and relative comparison of the proposed AF scheme with the conventional device and troubleshooting to implement the liquid lens array with required specification. The fluidic lens has a variety of applications due to its inherent property by which it can change the focal length by controlling electrical power without any mechanical moving part, which guarantees the strong durability and reliability. Fluidic lens consisting of PDMS (polydimethylsiloxane) membrane is a promising optical device due to the excellent optical properties. The other fluidic lens category is lens using a liquid wettability to activate the passive fluid. In this thesis, I am addressing various physical properties of fluidic lens using PDMS membrane and the fluidic device that is actuated by electrowetting principle which covers the electrical and mechanical specifications and operational properties that are determined by both hydrophobic layer and the lens design. Finally we fabricated the fluidic device of floating water in between passive oil phases to realize optical component for a device with high optical power that should consume extremely small electrical power. For a single lens based on PDMS membrane, the actuating force of the lens is generated by a voice-coil that exerts magnetic force to the ring-shape magnet, which moves upward and downward along the optical axis. The focal length was measured to be 25 $D$ and, it demonstrated clearness by showing images captured by a digital camera of 12 megapixels, which was set behind the lens at 10 $cm$ away. In the next step, I needed to solve the optical problem such as spherical aberration that was not controllable with the single curvature lens. In order for that purpose, a fluidic lens with bi-sided PDMS membranes of d...