An updatable three-dimensional display via direct optical fringe writing of computer - generated holographic stereograms in photorefractive polymer

Abstract

This thesis aims to assess the feasibility of an updatable three-dimensional display based on the direct fringe writing of computer-generated holographic gratings into a novel photorefractive polymer. The photorefractive polymer in question has been developed by Nitto Denko Technical Corporation and has many attractive properties for the 3-D display application, including long image persistence, rapid erasure, high diffraction efficiency, and large area; however, current holographic display systems based around its use involve interference methods that complicate their optical and computational architectures. The direct fringe writing architecture under question is poised as a simplifying and enhancing alternative to previous demonstrations of updatable holographic displays in photorefractive polymeric materials based around such conventional interference-based holographic stereogram techniques. In addition to simplifying optical architectures, direct fringe writing can allow for complete control of recorded hologram characteristics; interference fringes can be computed to simulate any arbitrary reference beam geometry and wavefront curvature. The system concept - comprised of fringe pattern generation on computer, fringe pattern transfer from SLM to photorefractive polymer, and spatial multiplexing for large-image generation - reintroduces accommodation cues to the resulting holographic images and represents a reduction of system footprint, complexity, and cost relative to the current interference-based systems. The adaptation of the Diffraction Specific Coherent Panoramagram fringe computation method - originally developed to drive AOM-based holographic displays at video rates while preserving all depth cues, including accommodation - to the current display architecture is presented and methods for direct fringe transfer from SLM to photorefractive polymer are depicted. Such methods for direct fringe writing are explored in simulation and experiment. Theoretical arguments for system performance are formulated in the context of a wave optics-based system analysis. Preliminary results of horizontal parallax-only images on this display are presented and directions for performance improvements and system extensions are explored.