Translation-invariant object recognition system using an optical correlator and a super- parallel holographic random access memory

Alexander Heifetz John T. Shen Jong-Kwon Lee Renu Tripathi M. S. Shahriar Northwestern University Department of Electrical and Computer Engineering Evanston, Illinois 60208 Abstract. We demonstrate a translation-invariant VanderLugt correlator VLC for a set of images stored via holographic angle multiplexing of volume gratings in a polymeric substrate. The images read out from the volume gratings are optically correlated in a translation-invariant manner with a dc-suppressed holographic filter. The quality and efficiency of this correlator are observed to be nearly as good as that of another VLC with images directly from a spatial light modulator used as inputs. This experiment is the first step toward realizing a novel optical image recognition system capable of identifying a query image through an exhaustive search in a large database of filter images stored in an ultrahigh capacity superparallel holographic random access memory SPHRAM . In this system, the identification of the query image is to be performed with a translation invariant, real-time VLC or a joint transform correlator JTC . © 2006 Society of Photo-Optical Instrumentation Engineers. DOI: 10.1117/1.2172354