Refractive elements produced in photopolymer layers

Abstract

Many new high-tech consumer products that are now under development require micro-optical elements. The development of these micro-optical devices has been carried out by many different researchers working in a variety of areas. This has lead to a large number of different fabrication techniques. We examine a novel fabrication technique that may allow the development of large arrays of elements quickly and cheaply. It is known that the exposure of dye sensitised Acrylamide layers to light can lead to material refractive index and volume changes. It is therefore proposed that a patterned exposure can be used to form a mixture of volume and surface relief patterning, enabling the production of optical elements. The examination of this fabrication technique, in particular the study of the processes that result in this volume change, may also lead to improvements in the photopolymer material so as to control shrinkage of these materials. The development of low shrinkage holographic recording materials is an active area in holography as most current photopolymer materials exhibit some volume change during the recording process. This has implications for the fidelity of the replayed image. This is of crucial importance in areas such as data storage systems. The further study of this process also has implications for the wider holographic research community. It is important to understand the surface relief profile of the holographic element prior to extracting grating parameters as surface relief effects may influence the experimental data. In this paper we describe initial experimental attempts to produce micro-optical elements for use in the visible spectrum using patterned exposure of an Acrylamide based photopolymer material.