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Proceedings Paper

Optical pattern-recognition with the real-time phase only filters and wavelet matched filters
Author(s): Yunlong Sheng; Danny Roberge; Luiz Goncalves Neto; Lixin Shen; Gilles Paul-Hus
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Paper Abstract

The spatial light modulator (SLM) is a key element of an optical processor. The limitations of the currently available SLM's are their limited phase and amplitude modulation capacity, limited space bandwidth product (SBWP) and limited speed. We use the commercial liquid crystal television (LCTV) as a SLM and build a real-time on-axis phase-only opticai correlator. This approach permits efficient use of the SBWP of the SLM (200 x 200 and 440 x 480 for new type of LCTV) and provides high light efficiency"2. Various continuous phase-only holograms, matched filters, circular harmonic filters and composite filters have been implemented with this coupled mode modulation SLM. The wavelet transform (WT) is a new mathematic tool for multiresolution local analysis of non-stationary and fast transient signals. It is efficient for local processing on edges, textures and deterministic objects in 2-D images3. We propose the wavelet matched filter (WMF) that performs the WT for edge enhancement and the matched filtering for correlation in a single step for automatic pattern recognition. Optics has advantage for shift invariant WT with the wavelet in the preselected frequency band and orientation4. The composite wavelet matched filter (CWMF) is a non-linear combination of the WMF's that produces desired outputs for a given set of objects. Both the WMF and CWMF are optically implemented with the couplemode modulation LCTV.

Paper Details

Date Published: 5 August 1994
PDF: 5 pages
Proc. SPIE 2321, Second International Conference on Optoelectronic Science and Engineering '94, (5 August 1994); doi: 10.1117/12.182104
Show Author Affiliations
Yunlong Sheng, Univ. Laval (Canada)
Danny Roberge, Univ. Laval (Canada)
Luiz Goncalves Neto, Univ. Laval (Canada)
Lixin Shen, Univ. Laval (Canada)
Gilles Paul-Hus, Univ. Laval (Canada)

Published in SPIE Proceedings Vol. 2321:
Second International Conference on Optoelectronic Science and Engineering '94
Wang Da-Heng; Anna Consortini; James B. Breckinridge, Editor(s)

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