Abstract: An embodiment of the invention, to provide a recording method and a storage medium for BCA data with high reliability for a storage medium and a method for reproducing BCA data from the storage medium, and an information recording apparatus and an information reproducing apparatus. In a conventional optical disk, low reliability data is recorded in a data area of BCA. Thus, the thickness of a film material for use in a recording layer oriented to BCA data or close to the inner periphery of the storage medium in the vicinity thereof is formed in uniform thickness by using a substrate of the storage medium, the substrate being formed by being suctioned by means of adsorbing mechanisms formed in an arc shape so as to integrated two of the adsorbing mechanisms to be adjacent to each other.

Abstract: There is disclosed an optical information recording device using a multilayer optical disc as a recording medium, in which the number of components of the device is reduced. The optical disc has, e.g., one recording layer with prepits and a plurality of recording layer without prepits. An optical pickup included in the information recording device includes a switchable lens element to focus laser beams to be applied to the multilayer optical disc onto two adjoining recording layers. A tracking error signal offset obtained for a recording layer with prepits is stored. Recording an information signal into a recording layer from which a tracking error signal cannot be detected is performed, while maintaining the accuracy of positioning on track with respect to the prepits based on the stored offset. When reading out an information signal, tracking control based on the prepits of recorded information signals is exerted.

Abstract: An optical data recording/reproducing device, wherein the number of reflection in an optical path of coherent light formed between a coherent light source and an optical disk is twice or a larger even number of times, and the array direction of the coherent light source and photodetectors is substantially parallel to the face of the optical disk, resulting in a smaller size in the direction corresponding to the thickness of the optical disk.

Abstract: A pickup head for use in optical disk systems such as compact disk players or CD-ROM computer memory includes a holographic optical element that has two decision regions that greatly simplify the design of the pickup head. The two decision regions diffract light that encounters the holographic optical element in two different directions, respectively. The amount of light power incident upon each decision region is utilized to determine a focus error signal and to interpret information stored on the compact or optical disk.

Abstract: An optical disk recording system including a record medium is disclosed for providing an accurate track crossing count and an accurate track following signal. A first embodiment utilizes off-centered wobbled areas located in the headers of the record medium. The high frequency content of a first signal is combined with the low frequency content of a second signal, which is generated using the wobbled areas. In another embodiment, light-reflective discontinuities are provided in the header areas of the record medium. A qualifier and an AGC are utilized in providing a corrected track following signal. In still another embodiment, reflective discontinuities are located in the servo areas of the record medium. In such an embodiment, it is preferred that there be a fixed gain adjustment to a radial push-pull signal.

Abstract: An optical disk recording system including a record medium is disclosed for providing an accurate track crossing count and an accurate track following signal. A first embodiment utilizes off-centered wobbled areas located in the headers of the record medium. The high frequency content of a first signal is combined with the low frequency content of a second signal, which is generated using the wobbled areas. In another embodiment, light-reflective discontinuities are provided in the header areas of the record medium. A qualifier and an AGC are utilized in providing a corrected track following signal. In still another embodiment, reflective discontinuities are located in the servo areas of the record medium. In such an embodiment, it is preferred that there is a fixed gain adjustment to a radial push-pull signal.

Abstract: An optical disk recording system including a record medium is disclosed for providing an accurate track crossing count and an accurate track following signal. A first embodiment utilizes off-centered wobbled areas located in the headers of the record medium. The high frequency content of a first signal is combined with the low frequency content of a second signal, which is generated using the wobbled areas. In another embodiment, light-reflective discontinuities are provided in the header areas of the record medium. A qualifier and an AGC are utilized in providing a corrected track following signal. In still another embodiment, reflective discontinuities are located in the servo areas of the record medium. In such an embodiment, it is preferred that there be a fixed gain adjustment to a radial push-pull signal.

Abstract: An optical disk recording system including a record medium is disclosed for providing an accurate track crossing count and an accurate track following signal. A first embodiment utilizes off-centered wobbled areas located in the headers of the record medium. The high frequency content of a first signal is combined with the low frequency content of a second signal, which is generated using the wobbled areas. In another embodiment, light-reflective discontinuities are provided in the header areas of the record medium. A qualifier and an AGC are utilized in providing a corrected track following signal. In still another embodiment, reflective discontinuities are located in the servo areas of the record medium. In such an embodiment, it is preferred that there is a fixed gain adjustment to a radial push-pull signal.

Abstract: The present invention relates to an optical head of an optical disk apparatus and a method of making the same, and more particularly, to an optical head which projects a light spot onto a track recess, receives the reflected light of the light spot by at least two photoelectric converters and focuses the light spot based on a differential output from the photoelectric converters. The optical head can accurately focus the light spot even if the reflected light beams that are nonuniform in intensity due to the influence of the comatic aberration of a lens composing the optical head are projected on to the photoelectric converters. This is because the influence of the comatic aberration of the lens is corrected for by marking the direction of central parallel ones of S-like interference fringes on the lens and optically forming a predetermined angle between the marked direction and the direction of the track recess.

Abstract: A composite wobbled tracking servo system uses a rotary optical disc which has a header field and a data field alternately arranged along the direction of rotation to provide a sector, and which includes pregrooves formed in at least the data field and at least one pair of wobbled track marks disposed in the header field in a relation wobbled relative to the center of a track. A light spot is directed toward and onto the optical disc to detect a push-pull tracking error signal from the reflection of the light spot diffracted by the pregroove, and a wobbled tracking error signal is detected from the reflection of the light spot traversing the wobbled track marks. The push-pull tracking error signal is corrected on the basis of the wobbled tracking error signal to attain the tracking control with higher accuracy, thereby eliminating an undesirable track offset attributable to tilting or eccentricity of the optical disc.

Abstract: A composite wobbled tracking servo system uses a rotary optical disc which has a header field and a data field alternately arranged along the direction of rotation, and which includes pregrooves formed in at least the data field and at least one pair of wobbled track marks disposed in each of the header fields in a relation wobbled relative to the center of a track. A light spot is directed toward and onto the optical disc to detect a push-pull tracking error signal from the reflection of the light spot diffracted from the pregroove, and a wobbled tracking error signal is detected from the reflection of the light spot passing the wobbled track marks. After attenuating the gain of the wobbled tracking error signal by a low-pass filter so that the gain of the wobbled tracking error signal becomes equal to that of the push-pull tracking error signal at a frequency fe satisfying the relation1/50.multidot.N.multidot.fd<fe<1/5.multidot.N.multidot.