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The optical disc has become a viable candidate for mass digital data storage. Its unique characteristics make it suitable for archival, wideband, high density record and playback applications, as well as those requiring fast access to a large data base. RCA has been pursuing the development of such systems for government mass data storage and retrieval requirements. This work is centered around a unique "tri-layer" optical disc structure, which offers high sensitivity and signal-to-noise (SNR) at very high packing densities. The two major areas of pursuit are record and playback at data rates of 200 Mb/s or more and multiple-disc record and playback units for very large on-line capacities. Record and playback at high data rates are achieved through simultaneous multiple, parallel-channel operation. Single-channel rates of 50 Mb/s and multiple-channel rates of 150 Mb/s have been demonstrated on laboratory breadboard equipment. Concept designs for multiple disc record and playback systems are centered around two "jukebox" configurations, which can provide fast automatic access to large on-line data stores. A feasibility design for a reader unit with an access time of three seconds to 1013 bits (100 discs) has been performed. A second concept provides a capability of both record and playback of 50 Mb/s with an access time of seven seconds to 1013 bits.
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