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Proceedings Paper

Microlens array processor with programmable weight mask and direct optical input
Author(s): Volker R. Schmid; Ernst H. Lueder; Gerhard Bader; Gert Maier; Jochen Siegordner
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Paper Abstract

We present an optical feature extraction system with a microlens array processor. The system is suitable for online implementation of a variety of transforms such as the Walsh transform and DCT. Operating with incoherent light, our processor accepts direct optical input. Employing a sandwich- like architecture, we obtain a very compact design of the optical system. The key elements of the microlens array processor are a square array of 15 X 15 spherical microlenses on acrylic substrate and a spatial light modulator as transmissive mask. The light distribution behind the mask is imaged onto the pixels of a customized a-Si image sensor with adjustable gain. We obtain one output sample for each microlens image and its corresponding weight mask area as summation of the transmitted intensity within one sensor pixel. The resulting architecture is very compact and robust like a conventional camera lens while incorporating a high degree of parallelism. We successfully demonstrate a Walsh transform into the spatial frequency domain as well as the implementation of a discrete cosine transform with digitized gray values. We provide results showing the transformation performance for both synthetic image patterns and images of natural texture samples. The extracted frequency features are suitable for neural classification of the input image. Other transforms and correlations can be implemented in real-time allowing adaptive optical signal processing.

Paper Details

Date Published: 9 March 1999
PDF: 10 pages
Proc. SPIE 3715, Optical Pattern Recognition X, (9 March 1999); doi: 10.1117/12.341299
Show Author Affiliations
Volker R. Schmid, Univ. Stuttgart (Germany)
Ernst H. Lueder, Univ. Stuttgart (United States)
Gerhard Bader, Univ. Stuttgart (Germany)
Gert Maier, Univ. Stuttgart (Germany)
Jochen Siegordner, Univ. Stuttgart (Germany)

Published in SPIE Proceedings Vol. 3715:
Optical Pattern Recognition X
David P. Casasent; Tien-Hsin Chao, Editor(s)

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