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A polymeric optical pattern-recognition system for security verification

Naturevolume 383pages5860 (1996) | Download Citation



POLYMERS that exhibit the photorefractive effect—a light-induced modulation of refractive index—are emerging as attractive materials for optical devices and processing systems1,2. Here we demonstrate one such application using our recently developed high-efficiency photorefractive polymer2. The polymer provides a nonlinear medium in which real-time all-optical image correlation, and hence pattern recognition, can be accomplished. This forms the basis of an optical security system, whereby documents are encoded with practically invisible phase masks (such masks are difficult to forge), which may then be rapidly screened to verify the authenticity of the documents. The wavelengths at which our optical system operates are compatible with commercial low-power semiconductor laser diodes, and the system can be integrated into a compact device at low cost.

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    • K. Meerholz

    Present address: Department of Physical Chemistry, Ludwig-Maximilian University, Munich, 80333, Germany


  1. Optical Sciences Center, University of Arizona, Tucson, Arizona, 85721–0094, USA

    • B. L. Volodin
    • , B. Kippelen
    • , K. Meerholz
    •  & N. Peyghambarian
  2. Electrical and Systems Engineering, University of Connecticut, 260 Glenbrook Road, Storrs, Connecticut, 06269, USA

    • B. Javidi


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