Abstract: A DVD-RAM disk reproduction apparatus for reducing an error during detection of ID data, which includes a first operational amplifier for obtaining a sum signal resulting from the addition of four picked-up signals picked up by divided-by-four photodiodes from a DVD-RAM disk having a header region and a recording region, second and third operational amplifiers for respectively obtaining two sum signals corresponding to the upper and lower regions of the header region resulting from the addition of the first and second picked-up signals and the third and fourth picked-up signals, respectively, a fourth operational amplifier for obtaining a difference signal between the two sum signals, a header region detector for detecting upper and lower header region signals corresponding to the upper header region and the lower header region based on the difference signal, and detecting a header region signal corresponding to a header region by logically summing the two detected signals, a first multiplexer for selecting o

Abstract: An optical pickup of an optical disk drive. The optical pickup includes a laser beam source for generating a laser beam; a pickup base having an objective lens for projecting the laser beam generated from the laser beam source to an information recording surface of an optical disk; a variation adjusting plate which is movably disposed on the pickup base to be moved in vertical and lateral directions, and has a rotational hole formed at a central portion thereof; and a rotation adjusting plate including a rotational section having a predetermined curvature which is inserted into the rotational hole of the variation adjusting plate, and with a laser beam source fixed therein, the rotation adjusting plate being rotated with respect to the variation adjusting plate. An optical system including a collimating lens and a reflective mirror is fixed to the pickup base.

Abstract: An optical pickup device including an objective lens which is compatible with a plurality of optical disks of respectively different specifications, such as a digital versatile disk (DVD), a compact disk-recordable (CD-R) medium, a compact disk (CD) and a laser disk (LD). The optical pickup device includes a laser source to emit light, an objective lens to focus the light emitted from the laser source on respective information recording surfaces of a plurality of optical recording media as an optimal optical spot, and an optical detector to detect light reflected from the information recording surface of the optical recording medium on which the optical spot has been focused and transmitted through the objective lens. The objective lens includes a first lens area, a second lens area, and a third lens area to focus the light emitted from the laser source.

Abstract: An optical pickup includes a variable iris having a numerical aperture is adjusted according to wavelength of light and can be compatibly used for discs having respectively different specifications.

Abstract: A method for forming a multilevel interconnection between a polycide layer and a polysilicon layer is disclosed. The multilevel interconnection comprises: forming a first impurity-containing conductive layer on a semiconductor substrate; forming a first silicide layer, having a first region thinner than a second region, on the first impurity-containing conductive layer; forming an interlayer dielectric layer in other than the first region; forming a contact hole for exposing the first silicide layer of the first region; and connecting a second impurity-containing conductive layer to the first silicide layer through the contact hole.

Abstract: An error signal detecting apparatus for an optical pickup employing a hologram grating, including a sensing lens for focusing light reflected from a recording medium, a hologram grating having first through fourth pattern regions arranged clockwise in a 2.times.

Abstract: A multilevel interconnection between a polycide layer and a polysilicon layer and a method of forming thereof are provided. The multilevel interconnection comprises: a first impurity-containing conductive layer formed on a semiconductor substrate; a first silicide layer, having a first region thinner than a second region, formed on the first impurity-containing conductive layer; an interlayer dielectric layer formed in other than the first region; a contact hole for exposing the first silicide layer of the first region; and a second impurity-containing conductive layer connected to the first silicide layer through the contact hole. Therefore, increases in contact resistance between conductive layers can be prevented.

Abstract: A magnetooptical recording/reproducing apparatus including a light source for emitting light, an object lens for condensing the light onto a magnetooptical disk, a polarization beam splitter in an optical path between the light source and the object lens, a first holographic device for diffracting an ordinary beam from the light passing through the polarization beam splitter after being reflected from the magnetooptical disk and allowing an extraordinary beam to pass therethrough unaltered, a second holographic device for splitting the ordinary and extraordinary beams passed through the first holographic device into a plurality of beams, and a photodetector for detecting the beams passing through the first and second holographic devices.

Abstract: An optical pickup apparatus compatible with disks having different thicknesses is provided. The optical pickup apparatus includes an optical source, a beam splitter for changing the direction of the incident beam, an objective lens which is located between the optical source and the disk for focusing the incident beam to form an optical spot on the disk, and a photodetector for detecting information and error signals by receiving the beam which is reflected from the disk and passed through the beam splitter. A hologram optical element (HOE) is provided between the beam splitter and the photodetector for diffracting the beam reflected from the disk into a zero-order beam and a positive first-order beam. The photodetector includes a first photodetector and a second photodetector which receive the zero-order beam and the positive first-order beam, respectively.

Abstract: A high density compact disc having tracks for recording large amounts of information reproducible for a long interval of time is disclosed. In order to increase the track density, a recording surface on a substrate is divided into grooves and lands to thereby form tracks, and pits representing information signals are arranged in both the grooves and the lands. Here, the groove is formed at an optimized predetermined depth, depending on the wavelength of light used to read the information recorded on the disc and the refractive index of a disc substrate, to thereby reduce crosstalk caused by pits of an adjacent groove or land during reproduction. Accordingly, the present invention is effective in enhancing the practicality of the compact disc as a medium for preserving large amounts of information.

Abstract: A high-density magneto-optical disk apparatus is provided for removing a cross talk between signals of an adjacent track with respect to a track to be reproduced during reproduction of a signal recorded on a magneto-optical disk. In the case that a track pitch is narrowed for high-density recording in a magneto-optical disk apparatus, a cross talk occurs between a track to be detected and an adjacent track thereto. The magneto-optical disk apparatus uses a phase modulation optical element to form an optical spot having a linear polarizing state in a reproduction track and a circular polarizing state in an adjacent track, on the recording surface of the magneto-optical disk. Accordingly, although a track pitch is considerably reduced compared with the optical spot, a signal interference effect, that is, a cross talk between tracks can be removed to thereby provide a high-density magneto-optical disk.

Abstract: An optical pickup for high-density recording/reproducing, which can read the information recorded at a close interval to exceed the limit of a given cut-off frequency, includes an objective lens having divided portions for respectively transmitting a zero-order optical component and .+-.1st-order diffracted components. To detect a signal for reproduction, a focusing lens is used for focusing the zero-order component and .+-.1st-order diffracted components passing back through the objective lens so as to mutually interfere. Stable high-density optical recording/reproduction can be realized regardless of the numerical aperture of the objective lens and the optical wavelength.