Abstract: A multi-track optical disk reader is provided having an optical pickup including multiple reading beams arranged in a pattern, such that each beam is directed towards a track to be read. The optical pickup is at least partly mounted on a swing-arm mechanism that orients the reading beam pattern with respect to the tracks being read. Methods and apparatus are provided for maintaining a desired position of the reading beams with respect to the tracks on an optical disk.

Abstract: Methods and apparatus are provided for detecting and correcting magnification errors while simultaneously reading or writing multiple data tracks with a multi-beam optical disk drive. An optical head for the optical disk drive includes a plurality of laser diodes that generate multiple light beams for reading from or writing to the optical disk, means for detecting a magnification error, and means for compensating for the magnification error to align the multiple light beams with multiple data tracks. A number of opto-mechanical systems are provided for correcting the magnification errors in the beams.

Abstract: The present invention provides digital read channel circuitry for an optical disk reader. An RF signal corresponding to a track on the optical disk is sampled to provide digital samples corresponding to the RF signal. The samples are taken at a rate that may differ from the channel bit rate of the RF signal. The digital samples are then processed to provide data at the channel bit rate. Multiple digital read channels may be used to read multiple tracks of an optical disk simultaneously. The multiple RF signals may be sampled based on a sample clock common to the multiple digital read channels.

Abstract: An optical pickup for simultaneously reading a plurality of data tracks of an optical storage medium is provided. The optical pickup uses a diffractive element to split an illumination beam into a plurality of reading beams which are projected onto a plurality of tracks of the optical storage medium. Apparatus and methods are shown for improving the optical characteristics of the optical pickup by reducing vignetting, optical aberrations, and field curvature. These improvements are achieved by relocating the diffractive element at a greater distance from the laser source, so that a diffractive element having a larger period, and a smaller angle between diffractive orders may be used. The apparatus and methods shown also reduce the number of components and the manufacturing cost of the optical pickup.

Abstract: Methods and apparatus are provided for synchronously reading data from multiple tracks of an optical disk using multiple illumination beams. Circuitry is provided for use with a photodetector array to read and buffer data in parallel from the multiple adjacent tracks, while asynchronously providing processed data to a host processor. Circuitry is further provided for concurrently processing the signals read from the multiple data tracks to recover the data stored in the tracks.

Abstract: In a CD-ROM reader system wherein five adjacent tracks of a CD-ROM are separately illuminated by five light beams of an optical pickup, a recorded data readout system simultaneously reads the recorded data of the separate tracks by detecting the received light outputs of the returned beams, and outputs the data in the sequence in which it was recorded. For example, if one light beam becomes unreadable by the recorded data readout system, the system will read the recorded data using the remaining four light beams. This readout is performed in recurring operations in which data is read for approximately one revolution of the CD-ROM; then, after there are no longer any gaps in the combined data, the pickup is track-jumped forward by approximately two tracks. At this point the recorded data is again read for one revolution, and the process repeats.

Abstract: The present invention provides an optical system having a read mode, during which multiple tracks of an optical disk are simultaneously read, and a write mode, during which data is written to at least one track of the optical disk. The multiple light beams employed during read mode may be generated by a single laser diode operated at low power used in combination with a diffractive element, multiple laser diodes, or combinations thereof.

Abstract: A focus detection system for use in a multi-beam optical pickup assembly is provided that uses an optical element, either a holographic element or diffractive element, to split beams reflected off of a data-bearing surface of an optical disk into a plurality of data beams and a plurality of focus beams. The optical element also introduces astigmatism into the focus beams. The focus beams are projected onto focus detectors configured to account for overlap between adjacent focus beams to produce an accurate focus error signal.