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Proceedings Paper

Storage of multivolume holograms using the phase-encoding technique
Author(s): Theo T. Tschudi; Cornelia Denz; Jan Lembcke; Markus Sedlatschek
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Paper Abstract

Reconfigural volume holograms are important for a wide range of multiple data storage applications, including optical interconnection systems, image processing and neural network models. Several techniques for multiplexing to obtain a large number of stored images which can be recalled independently have been developed. But even the most promising of these multiplexing techniques, angular multiplexing using the selectivity of the Bragg-condition, revealed to be limited primarily because of cross-correlation noise. Other problems are not less severe. In this paper we present an alternative approach implementing a phase coding method of the reference beam. Phase encoding has been discussed for interconnecting vector arrays in thin holograms and to perform array interconnections by correlation of a reference beam with a supplementary phase-coded input beam. In contrast to these investigations, we use a reference beam phase coding method in thick volume holographic media, taking thus full advantage of the selectivity of the Bragg-condition in volume storage media. In our experiments, we stored with pure and deterministic orthogonal phase references 64 images into a photorefractive BaTiO3-crystal. For this we developed a special phase modulator on the basis of a liquid crystal display. Good reconstruction with low crosstalk could be observed. Compared to other multiplexing techniques as angular multiplexing, our method allows high storage capacity without alignment problems. Moreover, easy, light efficient as well as immediate image retrieval without any time delay is possible. Experimental setup and results will be presented. We will especially discuss in detail advantages and disadvantages of this coding method compared to others.

Paper Details

Date Published: 8 March 1995
PDF: 1 pages
Proc. SPIE 2461, ROMOPTO '94: Fourth Conference in Optics, (8 March 1995); doi: 10.1117/12.203545
Show Author Affiliations
Theo T. Tschudi, Institute of Applied Physics, TH Darmstadt (Germany)
Cornelia Denz, Institute of Applied Physics, TH Darmstadt (Germany)
Jan Lembcke, Institute of Applied Physics, TH Darmstadt (Germany)
Markus Sedlatschek, Institute of Applied Physics, TH Darmstadt (Germany)

Published in SPIE Proceedings Vol. 2461:
ROMOPTO '94: Fourth Conference in Optics
Valentin I. Vlad, Editor(s)

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