Fuess, Davidenas & Meadows
Optoelectronic associative memory using parallel-readout optical disk storage
A high capacity (1 Gbyte), high throughput (1.1 Gbyte/s) motionless-head parallel-readout optical disk, and a detector array integrated on substrate with an Si/PLZT Exclusive-NOR gate array, implement a fast retrieval (25 ms) associative memory/content addressable memory capable of 10.sup.10 bit-operations per second. The disk stores arrayed 1-D holograms, preferably computer-generated from 128.times.128 pixel images by Fourier transform. Reverse transform upon disk readout is by lenses, preferably by a single hybrid refractive/diffractive lens. The reconstituted 2-D image, or optical word, is detected and compared to an electrical data word in an fast integrated optoelectronic circuit. The circuit permits (i) a variably preset "match" detection threshold, and (ii) dynamically variable, sub-image, field size of the search. In a first mode of operation all images (or sub-images) that are sufficiently close to a preset query threshold are retrieved in one disk rotation. In a second mode, Hamming distances for all images (sub-images) are calculated during a first disk rotation, and the identified best match(es) is (are) retrieved on a subsequent rotation. In a third mode a query image can be classified relative to all images upon a disk during one rotation of the disk. In still other modes the associative memory can search for images and sub-images (optical words) of variable size in parallel.
The Regents of the University of California
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Gokce Sadik C. Ashok V. Philippe J.
Yayla Esener Krishnamoorthy Marchand