Adaptive Electronically Controlled Liquid Crystal Microlens And Lens Array

Electrically controlled liquid crystal (LC) lens and lens array, as a kind of smart adaptive optical device, have several particular characteristics, for instance, small size, light weight, high performance, and fast response, and so on. Their focal length and other optical parameters can be modulated conveniently by applying voltage with variable RMS value. Because of the best electrically controllable optical performance, it can be widely used in many application fields such as adaptive optics, high-performance imaging detection, optical communications, optical interconnects, beam shaping, etc.The chapter 1 introduced the background of the project. The chapter 2 presented the LC material properties, and gave a careful analysis of the physical properties of nematic LC including LC director, dielectric anisotropy, elastic free energy density, and electro-optical effects. In chapter 3, the structures of a single LC lens and lens array were proposed according to the physical properties of the nematic LC and needed device structure, and thus the parameters of the device were determined. Based on the electromagnetic field theory, the electric field distribution required was calculated by the method of LaPlace difference iterative, and the results were shown in graphics. The simulation was in common with the expectation so as to provide a basis for device designing and fabrication.In chapter 4, the fabrication processes of the device were introduced. Firstly, the photomask for fabricating the controlling electrode over one side of the device was designed by software L-edit, and then the electrode was fabricated through photolithography, and wet chemical etching. The structure of LC aligned layer was made by coating a polyimide film, PI curing, and rubbing. Finally, the single LC lens and lens array were obtained through the processes of adding the isolation medium to construct LC cavity structure, filling LC materials into the cavity, and finally performing device packaging. We have acquired a complete set of technological flow for device fabrication and several key technological parameters.In chapter 5, common optical system for testing electrical/optical properties of the device was designed and constructed. The device's optical performances such as the optical focal spot size, the change of the focal length varied with voltage applied, and the interference pattern of monochromatic light, were tested. The results showed that all the configurations such as response time, the focal spot size, and the depth of focus, etc, have reached the expectation.Finally, a summary of the thesis and a suggestion for future work were given.