Andrew J. G. Strandjord

Flexible storage medium for write-once optical tape

A write-once data storage media has been developed which is suitable for optical tape applications. The media is manufactured using a continuous film process to deposit a ternary alloy of tin, bismuth, and copper. This laser sensitive layer is sputter deposited onto commercial plastic web as a single-layer thin film. A second layer is sequentially deposited on top of the alloy to enhance the media performance and act as an abrasion resistant hard overcoat. The media was observed to have laser write sensitivities of less than 2.0 njoules/bit, carrier-to-noise levels of greater than 50 dBs, modulation depths of approximately 100%, read-margins of greater than 35, uniform grain sizes of less than 200 angstroms, and a media lifetime that exceeds 10 years. Prototype tape media was produced for use in the CREO drive system. The active and overcoat materials are first sputter deposited onto three mil PET film in a single pass through the vacuum coating system, and then converted down into multiple reels of 35 mm X 880 m tape. One mil PET film was also coated in this manner and then slit and packaged into 3480 tape cartridges.

Thin-film coatings for flexible optical data storage

A write-once optical data storage media has been developed which is suitable for tape formats. The recording layer is a metal alloy system which is sputter deposited onto polymeric substrates as a single-layer thin film. The media are manufactured using a continuous sheet process, where the reflectivity of the film at 840nm can be selectively varied between 30 and 70%. These films have been characterized for laser write sensitivity, optical properties, surface chemistry, and environmental stability. An abrasion resistant hard overcoat is applied directly onto the active surface in a second vacuum deposition step. The media performance has been found to be compatible with direct hard-overcoats with no degradation in write sensitivity.