Rotationally invariant pattern recognition in a photorefractive joint transform correlator using circular harmonic filters and the wavelet transform

Hui Zhang, Colin M. Cartwright, Mei-Song Ding, Zhao-Qi Wang, Bao-Lai Liang, W. Allan Gillespie

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

A photorefractive joint transform correlator using circular harmonic filters and the wavelet transform for high discriminant and rotationally invariant pattern recognition is reported. In the experimental implementation, a photorefractive crystal, BSO, is used as the dynamic holographic medium and a bank of wavelet functions, derived from a mother Mexican-hat wavelet have been selected to achieve a band-pass operation in the Fourier domain. The zero-order and second-order circular harmonic components are used in the investigation. It is shown that, with the proper dilation factors, there is a trade-off between peak correlation intensity and signal-to-noise ratio (SNR) with the wavelet transform filters. With the second-order circular harmonic, an improvement of 63% in the SNR is achieved with only a 4% loss in the peak correlation intensity.
Original languageEnglish
Pages (from-to)383-391
Number of pages9
JournalOptics Communications
Volume195
Issue number5-6
DOIs
Publication statusPublished - 15 Aug 2001

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