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Proceedings Paper

Capture, encryption, compression, and display of digital holograms of three-dimensional objects
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Paper Abstract

Digital holography can be used to capture the whole Fresnel field from a reflective or transmissive object. Applications include imaging and display of three-dimensional (3D) objects, and encryption and pattern recognition of two-dimensional (2D) and 3D objects. Often, these optical systems employ discrete spatial light modulators (SLMs) such as liquid-crystal displays. In the 2D case, SLMs can encode the inputs and keys during encryption and decryption. For 3D processing, the SLM can be used as part of an optical reconstruction technique for 3D objects, and can also represent the key during encryption and decryption. However, discrete SLMs can represent only discrete levels of data necessitating a quantisation of continuous valued analog information. To date, many such optical systems have been proposed in the literature, yet there has been relatively little experimental evaluation of the practical performance of discrete SLMs in these systems. In this paper, we characterise conventional phase-modulating liquid-crystal devices and examine their limitations (in terms of phase quantisation, alignment tolerances, and nonlinear response) for the encryption of 2D and 3D data. Finally, we highlight the practical importance of a highly controlled discretisation (optimal quantisation) for compression of digital holograms.

Paper Details

Date Published: 9 June 2006
PDF: 11 pages
Proc. SPIE 6252, Holography 2005: International Conference on Holography, Optical Recording, and Processing of Information, 62521F (9 June 2006); doi: 10.1117/12.677154
Show Author Affiliations
Unnikrishnan Gopinathan, Univ. College Dublin (Ireland)
David S. Monaghan, Univ. College Dublin (Ireland)
Alison E. Shortt, National Univ. of Ireland/Maynooth (Ireland)
Thomas J. Naughton, National Univ. of Ireland/Maynooth (Ireland)
John T. Sheridan, Univ. College Dublin (Ireland)
Bahram Javidi, Univ. of Connecticut (United States)

Published in SPIE Proceedings Vol. 6252:
Holography 2005: International Conference on Holography, Optical Recording, and Processing of Information
Yury Denisyuk; Ventseslav Sainov; Elena Stoykova, Editor(s)

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