Fabrication and Testing of Computer Generated Holograms Using the MLA 150

Abstract

Grayscale lithography is a powerful technique that makes it possible to fabricate three-dimensional microstructures in photoresist. This thesis presents a newly developed process for achieving high quality grayscale lithography using the MLA 150 as well as initial results for various applications. Multiple photoresists including S1813, S1827 and AZ P4620 are characterized to provide a foundation for the developed fabrication process. A linearization regime is also presented that calibrates the MLA 150’s nominal grayscale output such that a result displaying equally spaced gray layers is achieved. The final grayscale lithography process is applied to fabricate a computer generated hologram (CGH) for use in adaptive optics for phase retrieval. A replication process is detailed that enables the exposed patterns to be replicated in NOA61 to form a usable and semi-permanent optical element. Comparisons made between the fabricated optical elements and the original designs demonstrate the success of the fabrication process.