Abstract: A method for adjusting the timing for sampling a reflected write signal is disclosed. The method comprises determining a reference timing event, and sampling the reflected write signal at first and second sampling times to produce first and second sampled signals, the first sampling time occurring after a first variable time delay following the reference timing event and the second sampling time occurring after a first fixed time delay following the first sampling time. The method further comprises comparing the magnitudes of the first and second sampled signals, and adjusting the first variable time delay in response to the comparison of the magnitudes of the first and second sampled signals so that the magnitudes of the first and second sampled signals are substantially equal.

Abstract: A recording apparatus and method are disclosed for forming marks on a recording medium. The recording apparatus includes an arrangement having an adjustable light source for producing a beam of light having first and second portions, with the second portion for recording marks on the medium, and an arrangement responsive to the first portion of the light beam and including a front facet detector positioned to receive the first portion of the light beam directly from the light source for producing a front facet signal. The recording apparatus also includes an arrangement for detecting light from the second portion of the light beam which is reflected from the medium and for producing a mark formation signal, and circuitry responsive to the front facet signal and the mark formation signal for producing a mark formation effectiveness signal.

Abstract: An apparatus and method for providing dynamic tracking error detection and control in an optical recording system in which an incident beam records data on a medium in the form of marks. A diffraction-based mark formation effectiveness (MFE) signal is generated by monitoring a reflected write signal in part of the return beam aperture or in multiple zones of the return beam aperture and is indicative of a characteristic of the marks formed on the medium. A position signal is generated to provide an indication of cross-track movement of the incident beam relative to a tracking structure on the medium. The tracking structure may be a wobbled groove on an optical disk recording medium. Variations in the diffraction-based MFE and position signals are correlated to provide a dynamic tracking error signal (TES).

Abstract: A magneto-optic head for reading and writing information on a magneto-optic recording medium so that diffraction effects can be monitored during writing is disclosed.

Abstract: An optical recording system for recording data on an optical medium comprising: an optical source capable of providing at least one write pulse incident upon the optical medium; a direct read during write (DRDW) verification and control system within the optical source having a capability of measuring light reflected from the optical medium into a return beam aperture, the DRDW system including a plurality of detectors configured to receive light from different areas of the return aperture; and a comparison circuit for comparing light received in different portions of the return aperture.

Abstract: An apparatus and method for use in an optical recording system in which an incident beam records data on an optical recording medium as marks and in which a return beam reflected from the medium is detected in an optical detector to provide a reflected write signal. A number of reflected write pulses of the reflected write signal are monitored in an interference detector. The peak voltage or other suitable characteristic of a reflected pulse corresponding to a mark following a relatively short land is compared to the same characteristic of another reflected pulse corresponding to a mark following a longer land. An error signal is generated based on the comparison and provides an indication of the amount of intersymbol interference (ISI) present during recording of the marks corresponding to the first and second reflected pulses.

Abstract: An apparatus and method for controlling laser power in an optical recording system in the presence of mark length variations produced by a groove wobble when an incident recording beam is off-track. An optical source supplies an incident write signal to an optical medium, such that data may be recorded on the medium during an incident write pulse as an optically-detectable mark. A reflection of the incident write signal from the medium is detected to provide a reflected write signal. A mark formation effectiveness (MFE) signal is generated from the reflected write signal to provide an indication of mark formation. A feedback circuit connected between the signal generator and the optical source controls a power level of the source in accordance with MFE signal variations produced by the wobbled groove.

Abstract: An apparatus and method for providing dynamic tracking error detection and control in an optical recording system in which an incident beam records data on a medium in the form of marks. A mark formation effectiveness (MFE) signal is generated by monitoring a reflected write signal and is indicative of a characteristic of the marks formed on the medium. A position signal is generated to provide an indication of cross-track movement of the incident beam relative to a tracking structure on the medium. The tracking structure may be a wobbled groove on an optical disk recording medium. Variations in the MFE and position signals are correlated to provide a dynamic tracking error signal (TES). The MFE and position signal variations may be correlated by, for example, multiplying the two signals together in a multiplier circuit, or using the position signal to control application of the MFE signal to particular inputs of a signal difference circuit.

Abstract: A level detector for detecting a voltage level of a signal, is disclosed. The level detector includes a signal comparator having a first input for receiving the signal; a first switch responsive to an output of the signal comparator to connect a first current source to an output of the detector. The first current source connected between a first voltage reference and the first switch, the detector output feeding back to a second input of the signal comparator, such that the first current source supplies current to the detector output until a voltage at the detector output is greater than the voltage level of the signal.

Abstract: A method and apparatus for, in an optical data recorder, focusing a recording light beam on a recording medium. In the apparatus, an optical head has focusing means movable in a direction perpendicular to the recording medium for changing the focus position of the recording light beam on the recording medium.

Abstract: An optical recording system and method which provide verification of recorded data, while the data is being written onto an optical recording medium, by detecting the rate of change of a reflected write pulse. The system includes an optical source for supplying a intensity-modulated incident write signal, having at least one write pulse, to an optical recording medium. The write signal records a logic level of the data on the medium as a mark having a distinct reflectivity. An optical detector detects a reflection of the incident write signal from the medium to provide a reflected write signal which includes a reflected write pulse corresponding to the incident write pulse. The reflected write pulse has a rate of change resulting from a change in reflectivity of the optical medium as the mark is formed thereon.

Abstract: The present invention provides an apparatus and method for controlling laser power in an optical recording system in the presence of multiple system degradations.

Abstract: A method and apparatus for, in an optical data recorder, maintaining a recording light beam in an on-track position on a recording medium. In the apparatus an optical head has a tracking arrangement movable in a direction parallel to the recording medium for changing the tracking position of the recording light beam on the recording medium.

Abstract: The present invention provides an apparatus and method for controlling laser power in an optical recording system. A recording system in accordance with the present invention includes an optical source for supplying an incident write signal to an optical medium, such that data may be recorded on the medium during an incident write pulse as a mark having a distinct reflectivity; a detector for detecting a reflection the incident write signal from the medium to provide a reflected write signal; a generator for generating a mark formation effectiveness signal from a reflected write pulse in the reflected write signal, to provide an indication of the quality of the mark; an error signal generator for generating an error signal from the mark formation effectiveness signal and a target value of the mark formation effectiveness signal; and a controller for controlling a write power level of the optical source by providing a partial correction of variation in the error signal.

Abstract: A fiber-optic array includes a plurality of optical fibers, each encased by a cladding material that significantly absorbs light. The refractive indices of the fiber core and its cladding are selected such that the acceptance angle of each fiber includes all rays incident upon the face of the fiber. Thus no unguided light enters one fiber and exits another fiber, and flare is controlled. By further having the cladding preferentially absorb totally internally reflected off-axis rays, the "effective" acceptance angle is limited to a value that provides increased depth of field in applications, e.g., involving film scanning.

Abstract: Film contact scanners are provided which irradiate a first surface of a film with a light source, and receive an image of the film from a second side of the film at an array of photosensors. In a first embodiment, the array of photosensors is disposed adjacent the film so that each photosensor receives light from a separate point on the film. In a second embodiment, a bundle of optical fibers is disposed between the film and the array of photosensors. A gap is provided between the film and a first end of the bundle of optical fibers. Each photosensor receives the light from one or more of optical fibers for producing a predetermined MTF. In the second embodiment, a portion of the film between the light source and the bundle of optical fibers is formed in a cylindrical shape. A linear direction of the cylindrical shape is oriented to permit the photosensors to scan the film in a first direction.