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Shift-invariant real-time edge-enhanced VanderLugt correlator using video-rate compatible photorefractive polymer
A Heifetz1, G S Pati, J T Shen
1Department of Electrical and Computer Engineering, Northwestern University, Evanston, Illinois 60208, USA. heifetz@ece.northwestern.edu
Applied Optics
|August 8, 2006
Summary
We developed a real-time shift-invariant VanderLugt correlator (VLC) using a novel photorefractive polymer composite. This system enables rapid searching of large optical image databases with enhanced correlation selectivity and shift invariance.
Area of Science:
- Optics and Photonics
- Materials Science
- Information Processing
Background:
- Photorefractive (PR) materials offer unique properties for optical information processing.
- VanderLugt correlators (VLCs) are crucial for pattern recognition and image retrieval.
- Limitations in PR material response speed and correlator shift invariance have hindered applications.
Purpose of the Study:
- To demonstrate a real-time shift-invariant VanderLugt correlator (VLC).
- To enhance correlation selectivity and overcome PR material response speed limitations.
- To enable fast, shift-invariant searching of large optical image databases.
Main Methods:
- Implementation of a VLC using a 37 microm thick bis-triarylamine side-chain polymer matrix photorefractive (PR) polymer composite.
- Operation at a 532 nm wavelength.
- Real-time edge enhancement to improve correlation selectivity.
- Degenerate four-wave mixing setup to measure angular bandwidth.
Main Results:
- Successful demonstration of a real-time shift-invariant VLC.
- Enhanced correlation selectivity achieved through real-time edge enhancement.
- High degree of shift invariance attributed to the thick PR polymer material.
- Experimentally measured angular bandwidth agreed well with theoretical predictions.
Conclusions:
- The developed VLC architecture overcomes PR material response speed limitations.
- The thick PR polymer composite enables high shift invariance for rapid database searching.
- This technology advances optical image processing and pattern recognition capabilities.
