3-D photopolymer disks for correlation and data storage, and cross-talk in volume holographic memories

Citation

Curtis, Kevin R. (1994) 3-D photopolymer disks for correlation and data storage, and cross-talk in volume holographic memories. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/6FK7-Z369. https://resolver.caltech.edu/CaltechETD:etd-10172005-155528

Abstract

This thesis considers the optical storage and processing of data using volume holography. First, cross-talk noise due to geometrical considerations is calculated for volume holographic memories. Cross-talk is due to energy diffracted from non-Bragg matched gratings. The SNR (signal-to-noise-ratio) of holographic memories due to cross-talk noise is calculated for Fourier transform holograms stored by angle, wavelength, phase-coded, and rotational multiplexing methods. Considerations include page size, geometry, angular bandwidth of the optical system, wavelength of the light used, material size, spatial light modulator (SLM) contrast, and the phase of the image plane. The SNR for angle multiplexed image plane holograms is also calculated and compared to the results for Fourier transformed angle multiplexed holograms. A comparison of the various multiplexing methods based on cross-talk is presented, and then the effect of geometry and material dynamic range is included to determine when cross-talk will be the dominant noise source. The use of photopolymers as a holographic element is then presented. The recording characteristics of the DuPont photopolymer are described and a method of multiplexing multiple holograms in the photopolymer is given. A new method for multiplexing holograms (called peristrophic multiplexing) is described. This method significantly increases the storage capacity of thin films. After this, a 3-D disk-based correlator and storage device using the photopolymer is described and demonstrated. In this device, holograms are multiplexed at a given spot and then disk rotation/head motion are used to access multiple spots on the disk. Theoretical correlation speed, read-out rates, and the storage capacity of the 3-D disk as limited by geometry and laser power are given.

Thesis Files