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Proceedings Paper

Coding And Quantization Of Computer-Generated Phase Holograms With Error Diffusion
Author(s): Severin Weissbach; Frank Wyrowski; Olof Bryngdahl
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Paper Abstract

Digital phase holograms offer the possibility to generate special light distributions with high diffraction efficiency. We call this distribution signal. Because phase holograms only influence the phase of the illuminating wave a coding of the spectrum of the signal is required. In practice that means: the discrete spectrum WiJ has to be modified by a nonlinearity operator to fulfil the phase hologram constraint |Wij|=1. In addition often a quantization of the phase values of Wij is desired. Due to the coding and quantization constraints noise may diminish the quality of the signal reconstruction. Several iterative coding techniques have been developed to overcome this shortcoming. We want to present a one step procedure for coding and quantization of digital phase holograms. It is related to the error correction and diffusion method suggested in electronic half toning (binarization of greytone images), and pulse density coding of amplitude holograms. Its basic idea is to diffuse the local error due to the coding or quantization at one pixel to the next to be processed. Flexibility exists in the choice of the diffusion weights which control the distribution of the errors and influence the shape of the noise in the Fourier plane of the manipulated distribution. We want to utilize this flexibility to spatially separate the noise from the signal.

Paper Details

Date Published: 26 October 1989
PDF: 10 pages
Proc. SPIE 1136, Holographic Optics II: Principles and Applications, (26 October 1989); doi: 10.1117/12.961691
Show Author Affiliations
Severin Weissbach, University of Essen (Germany)
Frank Wyrowski, University of Essen (Germany)
Olof Bryngdahl, University of Essen (Germany)

Published in SPIE Proceedings Vol. 1136:
Holographic Optics II: Principles and Applications

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