Abstract: Improvements in the shape of three-dimensional features displayed in optical recording structures, particularly in such structures displaying features of differing dimensional characteristics. The shape improvements include reductions in berm height and width, dual level data marks and tracking guides, and land areas projecting above or into the surface of the recording structure.

Abstract: Improvements in the shape of three-dimensional features displayed in optical recording structures, particularly in such structures displaying features of differing dimensional characteristics. The shape improvements include reductions in berm height and width, dual level data marks and tracking guides, and land areas projecting above or into the surface of the recording structure.

Abstract: A hybrid disc whose recordable-band grooves are wider and shallower than the pre-recorded ROM data pits. The ROM pits may be pre-recorded in ROM grooves that are at least as wide, but shallower than, the ROM pits. The ROM lands intervene between consecutive ROM pits, whether or not a ROM groove is provided. In the preferred embodiment, one beam of a dual beam apparatus records the ROM pits, while the other beam records the pre-grooves, and also records the ROM groove, if present. In most embodiments a thermal mastering process provides smooth feature surfaces to facilitate replication of the hybrid disc masters. The berms normally forming at the radial extremities of the pits and grooves in the masters, by thermal expulsion processes, may be reduced or eliminated by methods taught.

Abstract: A method and apparatus for manufacturing hybrid disc whose recordable-band grooves are wider and shallower than the pre-recorded ROM data pits. The ROM pits may be pre-recorded in ROM grooves that are at least as wide, but shallower than, the ROM pits. The ROM lands intervene between consecutive ROM pits, whether or not a ROM groove is provided. In the preferred embodiment, one beam of a dual beam apparatus records the ROM pits, while the other beam records the pre-grooves, and also records the ROM groove, if present. In most embodiments a thermal mastering process provides smooth feature surfaces to facilitate replication of the hybrid disc masters. The berms normally forming at the radial extremities of the pits and grooves in the masters, by thermal expulsion processes, may be reduced or eliminated by methods taught.

Abstract: A hybrid disc whose ROM grooves are less than 170 nanometers deep, and whose pre-recorded ROM data pits are more than 350 nanometers or less than 250 nanometers deep, as measured from the effective land level. The ROM pits may be pre-recorded in ROM grooves that are shallower than the ROM pits, where the ROM pits are narrower, of equivalent width or up to approximately 10% wider than the ROM grooves, respectively measured at half-depth, although the transverse extent of the ROM pits will not typically exceed that of the ROM grooves. The ROM lands intervene between consecutive ROM pits, whether or not a ROM groove is provided. In the preferred embodiment, one beam of a dual beam apparatus records the ROM pits, while the other beam records the R-band pre-grooves, and also records the ROM groove, if present. In most embodiments a thermal mastering process provides smooth feature surfaces to facilitate replication of the hybrid disc masters.

Abstract: A method to produce improvements in the shape of three-dimensional features displayed in optical recording structures, particularly in such structures displaying features of differing dimensional characteristics. The shape improvements include reductions in berm height and width, dual level data marks and tracking guides, and land areas projecting above or into the surface of the recording structure. The method includes dual and/or dithered beam writing onto the structure and improved composition of the active layer of the structure.

Abstract: Disclosed are improvements in the transverse sectional shape of three-dimensional features displayed in optical recording structures—discs, cylinders, cards, multi-layered devices and structures replicated from them—to increase Figure of Merit. The cross-sectional shape improvements include reductions in berm height and width, dual level data marks and tracking guides, and land areas projecting above or into the surface of the recording structure. Disclosed methods include dual and/or dithered beam writing onto the structure and improved composition of the active layer of the structure. Also disclosed are apparatus for producing such improved features on optical recording structures, according to one or more of the disclosed methods.

Abstract: Method and apparatus for improving the characteristics of the surface effects on a replicated optical disc the master for which is recorded on an optical recording apparatus which includes a writing light beam source and an optical modulator for modulating the intensity of the writing beam of light above and below a threshold level of a relatively moving recording medium in response to a modulator drive signal for recording information on the medium, the light beam being capable of forming a track of surface effects or indicia in the relatively moving master recording medium when the writing beam is above threshold and incapable of forming surface effects in the relatively moving recording medium when the writing beam is below threshold. The method includes receiving a substantially rectangular waveform intended to control the optical modulator.

Abstract: Method and apparatus for improving the characteristics of the surface effects on a replicated optical disc the master for which is recorded on an optical recording apparatus which includes a writing light beam source and an optical modulator for modulating the intensity of the writing beam of light above and below a threshold level of a moving recording medium in response to a modulator drive signal for recording information on the medium, the light beam being capable of forming a track of surface effects or indicia in the moving master recording medium when the writing beam is above threshold and incapable of forming surface effects in the moving recording medium when the writing beam is below threshold. The method includes receiving a substantially rectangular waveform intended to control the optical modulator.

Abstract: A composite disc in which a pattern of spaced glue dots is sandwiched between two disc halves. One of the disc halves is a dummy disc, and the other is a recordable optical disc. The pair of disc halves are joined together by depositing a pattern of spaced glue dots on the upper surface of one of the discs, positioning the second disc over the first, and contacting the lower surface of the second disc with the pattern of spaced glue dots. Preferably, the material of the glue dots is an ultraviolet curable contact cement, and, subsequent to the application of the pattern of dots on the dummy disc, and prior to joining the two disc halves, the glue dots are cured by being exposed to a source of ultraviolet light.

Abstract: Method and apparatus for improving the characteristics of the surface effects recorded on an optical disc, for use with an optical recording apparatus which includes a writing light beam source and an optical modulator for modulating the intensity of the writing beam of light above and below a threshold level of a moving recording medium in response to a modulator drive signal for recording information on the medium, the light beam being capable of forming a track of surface effects or indicia in the moving recording medium when the writing beam is above threshold and incapable of forming surface effects in the moving recording medium when the writing beam is below threshold.

Abstract: An optical storage media and information storage system and method for optically recording information in optically readable form. The DRAW recording medium of the present invention consists of a three layer structure: a transparent substrate; a uniform layer of a dielectric light-responsive material having a threshold energy level at which a physical change in the material occurs; and a highly electrically conductive and highly reflective overcoating on the opposite side of the light-responsive layer from the substrate. The recording method and system allow the concentration of the writing energy to a well defined volume within the thickness of the energy responsive layer or the uniform distribution of the energy throughout the layer by setting up a standing wave within the energy responsive layer by use of the electrically conductive reflecting layer.

Abstract: An optical storage media. The DRAW recording medium of the present invention consists of a three layer structure: a transparent substrate; a uniform layer of a dielectric light-responsive material having a threshold energy level at which a physical change in the material occurs; and a highly electrically conductive and highly reflective overcoating on the opposite side of the light-responsive layer from the substrate. The invention provides a DRAW recording medium which is capable of recording information immediately readable in accordance with the International Electrotechnical Commission optical disc standard for videodiscs.

Abstract: A videodisc recorder signal processing system and a recording method providing programmed control of the amplitude of the secondary (audio channel) carrier signals relative to the primary (video channel) carrier signal during recording. In one embodiment, the amplitude of the two audio carrier signals are varied in accordance with a preprogrammed profile to counteract the MTF effects of the recording system. In another embodiments, the amplitudes of the two audio carriers are varied in accordance with a preprogrammed pattern related to the relative criticality of the audio and video information recorded on the disc. The signal characteristics of the audio channels are improved by increasing the amplitude of the audio carriers. When no audio information exists, the audio carrier signals are substantially eliminated to maximize the quality of the video channel. At other times, the audio carrier signals are decreased to improve the video quality by reducing IM products.

Abstract: A modulator including a voltage controlled oscillator (VCO) having its center frequency stabilized to a reference frequency using a phase locked loop in which the low frequency range is increased by using frequency translation techniques. The VCO output signal is translated relative to the phase locked loop feedback signal so that an increased frequency division ratio can be used in the feedback loop and the effective frequency deviation at the phase comparator can be reduced by an arbitrary factor. This has the effect of increasing the allowable deviation at a given information signal frequency by that arbitrary factor. Likewise, a given deviation can be maintained for input information frequencies which are an arbitrary fraction of the low end cutoff frequencies of conventional modulators.

Abstract: A focus control system with a novel gain control circuit for continually varying the gain of the focus error signal based on the optical characteristics of the medium. As those optical characteristics change to decrease the amount of light available to the focus error detector, the gain of the focus error signal is increased so that the overall gain of the servo loop and the overall response of the servo to a focus error remains constant. This is accomplished by monitoring the optical characteristics of the medium which affect the focus error detector. In a multiple detector system, the outputs of all of the detectors are summed together. The resultant signal is a reflectivity or a transparency signal and is used in a novel circuit for controlling the servo gain.

Abstract: A signal processor and method for frequency compensating the drive signal for an optical modulator in an optical recording apparatus to make the exposure level modulation amplitude on the medium independent of the spatial frequency of the information being recorded. The processor compensates for exposure level modulation roll off at high spatial frequencies due to the finite size of the recording spot by increasing the amplitude of the modulator drive signal at high frequencies. The compensation is preferably the inverse of the modulation transfer function of the recording objective lens.

Abstract: An optical disc structure including two resilient disc members which are bonded together adjacent their outer peripheries and which include an air channel allowing communication between the chamber formed between the discs and the atmosphere. An information layer is formed on the inner surface of at least one of the members. When the members are spun, a pressure differential is caused tending to push the two members apart, thereby assuring that one member will not contact the information layer formed on the other member and that the two members will not be close enough together to cause optical interference.