Optical Bidirectional Associative Memories

Bart Kosko; Clark Guest

doi:10.1117/12.940062

6 June 1987 Optical Bidirectional Associative Memories

Bart Kosko, Clark Guest

Author Affiliations +

Proceedings Volume 0758, Image Understanding and the Man-Machine Interface; (1987) https://doi.org/10.1117/12.940062
Event: OE LASE'87 and EO Imaging Symposium, 1987, Los Angeles, CA, United States

Abstract

Four optical implementations of bidirectional associative memories (BAMs) are presented. BAMs are heteroassociative content addressable memories (CAMs). A BAM stores the m binary associations (A1, B1), ..., (Am, Bm) , where A is a point in the Boolean n-cube and B is a point in the Boolean p-cube. A is a neural network of n bivalent or continuous neurons ai; B is a network of p bivalent or continuous neurons bi. The fixed synaptic connections between the A and B networks are represented by some n-by-p real matrix M. Bidirectionality, forward and backward information flow, in neural nets produces two-way associative search for the nearest stored pair (Ai, Bi) to an input key. Every matrix is a bidirectionally stable hetero-associative CAM for boh bivalent and continuous networks. This generalizes the well-known unidirectional stability for autoassociative networks with square symmetric M. When the BAM neurons are activated, the network quickly evolves to a stable state of two-pattern reverberation, or pseudo-adaptive resonance. The stable reverberation corresponds to a system energy local minimum. Heteroassociative pairs (Ai, Bi) are encoded in a BAM M by summing bipolar correlation matrices, M = X1T Y1 + ... + XmT Ym , where Xi (Yi) is the bipolar version of Ai (Bi), with -1s replacing Os. the BAM storage capacity for reliable recall is roughly m < min(n, p)--pattern number is bounded by pattern dimensionality. BAM optical implementations are divided into two approaches: matrix vector multipliers and holographic correlators. The four optical BAMs described respectively emphasize a spatial light modulator, laser diodes and high-speed detectors, a reflection hologram, and a transmission hologram.

Citation Download Citation

Bart Kosko and Clark Guest "Optical Bidirectional Associative Memories", Proc. SPIE 0758, Image Understanding and the Man-Machine Interface, (6 June 1987); https://doi.org/10.1117/12.940062

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

;

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE