Optical storage media with discontinuous thin metallic films

DETAILED DESCRIPTION In accordance with this invention an optical storage medium for storing binary data by printing coding spots in the storage medium is provided.
The medium is adapted to be written upon by a focussed high intensity energy beam.
The medium comprises a substrate including a matrix material having a low melting point.
The improvement comprises the medium including particles of small size composed of islands of an energy absorbing material dispersed in an interior or exterior thin film layer (of a planar or non-planar configuration) of such particles juxtaposed with each other with small spacings whereby focussed energy can be directed to heat individual ones of the particles to cause a change of the reflectivity of the medium to record information at the sites where heating has occurred.
Preferably the film is a noble metal selected from the group consisting of gold, silver, copper, platinum, palladium, and rhodium.
The Drexler reference describes a recording medium commercially available which includes metal particles carried in a polymer matrix on a flexible disk with the particles dispersed in a film similar to an exposed photographic emulsion.
Drexler uses dispersed particles of metal rather than a single discontinuous thin film of metal.
Further, the particles are dispersed randomly, whereas in accordance with the instant invention, there are islands of metal in a single discontinuous layer.
Furthermore, the amount of metal included in the medium is far greater in quantity of the Drexler media since it is dispersed throughout the thickness of the medium.
Such a configuration tends to promote eruption of the particles from the medium causing ablation or vaporization of the medium.
In contrast, the thin films of nucleated metal used in accordance with this invention are deposited by vacuum deposition techniques such as evaporation, sputtering, or electron beam thermal deposition techniques.
These thin films coalesce rather than erupting.
In this invention the thermoplastic melts when the energy absorbing (metal) material is heated by the laser beam