Abstract: An erasable optical data storage medium including a substrate and a dual layer of a first material and a second material on the substrate. The dual layer is susceptible to expansion and contraction, to writing data thermally, to erasing data thermally and mechanically, and to reading data optically, the first material and the second material, respectively, being bonded together and remaining in the same physical state upon the expansion and relaxation of the dual layer. Methods and apparatus are also disclosed for recording data bits on the medium.

Abstract: An erasable optical data storage medium has an integral recording layer including an expansion zone and a retention zone having different optical and thermal-mechanical properties. A uniform integral layer of dyed polymer material has the dye leached out of the surface region and a second dye diffused into the surface region to create a retention zone. The retention zone has a higher elastic modulus and glass transition temperature than the underlying expansion zone and is adapted to absorb and transmit light which is centered about a different wavelength than the expansion zone. The medium is adapted to be used with a non-ablative and non-vesicular method to create and erase optically detectable deformations in the retention zone.

Abstract: An optical data storage medium includes a triple layer recording structure having an expansion layer, a retention layer and a very thin reflective layer interposed between the retention and expansion layers. The three layers are strongly bonded together so that the thermally and mechanically active expansion and retention layers can mechanically act upon each other through the intermediate reflective layer. The expansion and retention layers are dyed to selectively pass or absorb light of preselected wavelengths. The thin reflective layer is adapted to partially pass and partially reflect light of preselected wavelengths.

Abstract: An erasable optical data storage medium including a substrate and a dual layer of a first material and a second material on the substrate. The dual layer is susceptible to expansion and contraction, to writing data thermally, to erasing data thermally and mechanically, and to reading data optically, the first material and the second material, respectively, being bonded together and remaining in the same physical state upon the expansion and relaxation of the dual layer. Methods and apparatus are also disclosed for recording data bits on the medium.

Abstract: An erasable optical data storage medium has an embedded servo track and a subsurface recording interface. An erasable recording structure having two dyed polymer layers is separated from the servo track by a compression layer. The servo track is formed in a hard substrate which provides mechanical support for the medium. The medium is adapted to form non-vesicular data bumps projecting into the compression layer when exposed to a write laser beam of predetermined wavelength projected through the substrate and compression layer. The embedded servo track and recording interface are sufficiently close to each to be read simultaneously in the same focal plane.

Abstract: An erasable optical data storage medium has a polymer dual recording layer including an expansion layer bonded to a retention layer, each of the layers dyed to selectively absorb light in respective narrow wavelength bands. The retention layer has a glass transition temperature substantially above the glass transition temperature of the expansion layer, and is capable of undergoing substantial viscoelastic shear deformation while below its glass transition temperature. A first laser beam heats the expansion layer causing it to expand and cause viscoelastic deformation in the retention layer while the retention layer is below its glass transition temperature. A second laser beam is used to heat the retention layer above its glass transition temperature and relax the deformation, erasing the medium.

Abstract: An erasable optical data storage medium including a substrate and a dual layer of a first material and a second material on the substrate. The dual layer is susceptible to expansion and contraction, to writing data thermally, to erasing data thermally and mechanically, and to reading data optically, the first material and the second material, respectively, being bonded together and remaining in the same physical state upon the expansion and relaxation of the dual layer. Methods and apparatus are also disclosed for recording data bits on the medium.