Shift-invariant optoelectronic associative memory by using a cascade of correlators

We present a shift-invariant optoelectronic associative memory (OAM) which is realized in a cascade of correlators. The starting point is the OAM arch itecture proposed in 1995. Its crucial modification, which we propose, cons ists in the codification of each class of objects on the recognition filter by different carrier frequencies. This ensures the proper work of the syst em regardless of the location of the pattern in the input scene. As a resul t of such a filter design an additional intermediate layer has to be introd uced into the OAM between the thresholder and reconstruction layer. We pres ent a description and analysis of all elements of the modified OAM, with sp ecial regards to these subsystems (layers) which are particularly valid for the shift-invariant recognition and reconstruction. The final results of d igital analysis of the behavior of the shift-invariant OAM are included. (C ) 2000 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(00)0 11 04-1].