Promise of Optical Memories

A concept based on optical techniques may provide a long-sought ideal: a mass memory with archival permanence yet electronic accessibility. It is based on hologram storage on an erasable medium and compound addressing by pages and within pages. An array of light valves composes the page to be stored. The direction of illumination of the page composer, resulting from the deflection of a laser beam, determines the location on the storing medium at which a hologram of the page will be recorded (and the previous record erased). Addressing a record by a reference beam projects the stored pattern on a sensor array. The page composer and sensor array are physically combined with an electrically addressable transistor memory. In operation, the transistor memory acts as the internal memory of a computer that can be filled and emptied by a single pulse of illumination. A memory of 1010 bits with 105 pages accessible in microseconds and 105 bits per page accessible in fraction of a microsecond appears possible in the following demonstrated respects: holograms in films of MnBi, acoustic deflection, integrated sensor and memory arrays, and optic arrangements. There are resonable expectations for light shutter arrays and sufficient pulse power from lasers.