Abstract: A hybrid disc including a ROM prerecorded portion and a recordable information portion located closer to the axis of rotation of the disc than the ROM portion.

Abstract: In combination with a digital recording medium having recorded thereon individually addressable digital data files containing still images, motion sequences and sound sequences, an index print, having a plurality of index images representing the still images, motion sequences and sound sequences on the digital recording medium, the index images including a subject matter descriptor, an index code usable for addressing the individual digital data files, and a type indicator for indicating the type of subject matter contained in the data file.

Abstract: A method for writing and/or reading information on an optical recording element, such as an optical disk, utilizes a recording element comprising a recording layer having physical and optical properties which are optimized for phase-shift read-out. The optical properties of the recording layer give rise to a non-linear relative phase shift/layer thickness curve which, in combination with a predetermined nominal thickness of the recording layer, enhances the signal-to-noise ratio of the read-out signal.

Abstract: A recording element comprising a support having thereon a heat-deformable optical recording layer having a transparent ceramic overcoat characterized in that the overcoat has a thickness up to about 0.05 .mu.m is disclosed.

Abstract: An erasable, reusable recording element comprising a support having thereon a heat-deformable optical recording layer having a transparent overcoat is disclosed.

Abstract: An optical disc assembly for use with optical disc apparatus includes a flexible disc-shaped support. An annular retaining ring engages the support around its periphery. The support carries a record layer with an information storage region. Cooperating optical disc write/read apparatus has an annular, rotatable locating surface against which the support abuts. Annular spring means integral with the locating surface engage the retaining ring, applying a force to center the ring with respect to the axis of rotation of the locating surface, and to bring the support into a predetermined abutting force against the locating surface. This provides firm contact between the disc assembly support and the locating surface. The retaining ring holds the support in a first, predetermined circumferentially-symmetric storage tension. The abutting force of the support against the locating surface, induced by the spring means, may increase the tension in the support to a second, operating tension.

Abstract: A recording element is disclosed which is capable of providing high-quality, high information-density recording by thermal deformation. The element comprises a support having thereon a layer of amorphous material. The amorphous material is capable of being thermally deformed to form depressions surrounded by sharply defined ridges when impinged upon by a high energy-density recording beam. The amorphous material comprises either a binder and a dye or a certain solvent-coatable dye, Iosol Red. The amorphous material must have an absorption factor, as herein defined, greater than 20. The depressions which are formed in the described material are such that they are readable by a reading beam which is not absorbed by the material.

Abstract: Optical disc structure physically optimized for real-time recording and playback of high-density information and methods and apparatus pertaining to such disc structure. One disclosed disc embodiment is designed for heat-deformation recording and reflective read-out and, in regard to the chosen reading wave-length, is optimized in recording stratum thickness and optical constants for high sensitivity writing and high contrast, phase interference reading. Another disclosed disc embodiment is further optimized in thickness and optical constants with respect to a chosen writing wavelength to further enhance writing sensitivity and reduce requisite writing power.

Abstract: A recording element adapted for real-time writing and reading with light of a single given wave-length utilizes a recording stratum, including a heat-deformable dye-binder layer, overlying a reflective support and is characterized by the dye-binder layer having optical constants such that its reflectance versus thickness variation curve has a first reflectance minimum having a high depth of modulation and the recording stratum having a nominal thickness sufficiently greater than the thickness corresponding to the first reflectance minimum to effect reflection of a significant portion of light of such given wavelength.

Abstract: In accordance with the present invention, the optical characteristics of a thermal deformation record device are so altered that the device can be read back using the same beam as was used for recording. Moreover, the read beam can be used for playback at an arbitrarily high power level to enhance the signal-to-noise ratio of the recovered signal and yet not damage the deformation recording.

Abstract: Apparatus and method are disclosed for contact printing information from a master record carrier onto a replicate material of a type that emits gas during the contact print exposure (e.g., a diazo-film emulsion). It has been discovered that the emitted gas acts as an efficient lubricant of the master-replicate interface and contributes to relative movement between the master record carrier and the replicate material during the contact print exposure. In the case of videodisc replication, wherein video information is recorded in the form of billions of micron-sized apertures, such relative movement severely degrades the replicated imagery. To limit such relative movement, a preferred embodiment of the present invention provides contact printing apparatus, including a specially filtered exposing source, that substantially eliminates relative movement between the master record carrier and the replicate material.

Abstract: Light-control devices of the type having field-orientable, light-control elements supported in a solid elastomeric matrix are constructed in a manner providing improved uniformity in light-control and, in image display uses, improved resolution and contrast. Features of the improved construction include predetermined physical characteristics such as size, shape and/or location of the light-control elements within the matrix. Various methods for achieving such constructions include the steps of forming the desired array of elements and disposing the array in the matrix with relative positions of the elements maintained.