Abstract: The present invention relates to a method of manufacturing a multilayered disk capable of refraining from an interference at the adjacent layer when a specific layer of the multilayered layers is recorded or regenerated in an optical disk. According to the present invention, a method for manufacturing a multilayered disk having at least two recording layers is characterized by that a space between the two recoding layers is set to less than 10 ?m to refrain from an interference at the adjacent layer when one of the recording layers is recorded or regenerated. According to a method for manufacturing a multilayered disk and a method for removing an interlayer interference using the disk in the present invention, it is possible to design and manufacture a multilayered disk within a reflective signal range.

Abstract: The present invention relates to an optical pickup apparatus enabling to reproduce/record data of different kinds of disks in different thicknesses, using one single optical pickup. The optical pickup apparatus includes two objective lens, in which one objective lens has an incident plane and an outgoing plant formed of a flat plane at a designated radius domain from an optical axis, thereby preventing spherical aberration caused by the difference of the thickness between different kinds of disks.

Abstract: An optical pick-up device uses a holographic optical element that includes a holographic optical element, formed by combining a birefringence medium and an isotropy medium, for adjusting an optical route of a transmitted beam according to a polarizing direction and wavelength of an incident beam. The optical pick-up device has an objective lens for focusing the beam pass through the holographic optical element on an optical disk according to the wavelength of such beam.

Abstract: A tilt detecting apparatus of an information-recording medium having a photo diode for detecting a light reflected from an information-recording medium and outputting a light amount signal according to the detected light amount; and a calculating unit for calculating a radial tilt amount by using the light amount signal, wherein the photodiode is divided into a plurality of cells which are identified as regions according to a light amount of the reflected light, based on which a tilt signal is detected. A portion of the reflected light diffracted at the information-recording medium is detected by using the 8-divided photo diode, the region having a large difference in a light amount by the tilt and the region having a small difference in a light amount by the tilt in view of the characteristic of the reflected light are detected.

Abstract: An optical pickup apparatus that can adaptive for a plurality types of optical discs different in the layout condition such as a recording density, etc. and an optical recording/reproducing apparatus employing the optical pickup apparatus. In the optical pickup apparatus, first and second light sources generate a different wavelength of light beams. An optical system allows a light beam generated from any one of the first and second light sources to be selectively irradiated onto the optical disc and have an aperture number controller allowing the number of aperture of a light beam to have a different value. A photo detector detects the light beam reflected from the optical disc to be accessed to convert the same into an electrical signal. The apparatus is capable of accessing three types of optical discs different in the layout condition by utilizing an appropriate combination of a wavelength of the light beam with the number of aperture.

Abstract: A method of measuring thickness of an optical disc by using an interference effect of the optical disc layer is disclosed. The method includes detecting an intensity of a reflective light according to a wavelength of a light as spectrum data for each wavelength, converting the detected spectrum data for each wavelength into a spectrum value as a function of a wavelength that a refractive index is reflected, and detecting a position where the intensity of the reflective light has a peak as a thickness of a spacer layer and a cover layer respectively by converting the converted value into a length of an interference area for representing a layer thickness of the optical disc by the Fast Fourier Transform. The disclosed method has advantages for high precisely measuring thickness of an optical disc.

Abstract: A high-density multi-layer recording medium is provided with a first recording layer arranged within a layer of transparent material a first distance from a light incident surface of a recording medium and a second recording layer arranged a greater second distance from the light incident layer. The material forming the layer of transparent material on the recording medium typically has an index of refraction between about 1.45 and 1.70 with the first and second recording layers being arranged in an annular section of the substrate between about 63.5 &mgr;m and about 115.5 &mgr;m from the light incident surface with the separation between the two recording layer being between about 14 &mgr;m and 30 &mgr;m. Also disclosed is an apparatus for reading such recording mediums including a light source and a lens assembly arranged and configured to produce a light beam that enters the recording medium through the light incident surface and is focused on the two recording layers.

Abstract: An optical pick-up device uses a holographic optical element that includes a holographic optical element, formed by combining a birefringence medium and an isotropy medium, for adjusting an optical route of a transmitted beam according to a polarizing direction and wavelength of an incident beam. The optical pick-up device has an objective lens for focusing the beam pass through the holographic optical element on an optical disk according to the wavelength of such beam.

Abstract: An optical pickup apparatus that can adaptive for a plurality types of optical discs different in the layout condition such as a recording density, etc. and an optical recording/reproducing apparatus employing the optical pickup apparatus. In the optical pickup apparatus, first and second light sources generate a different wavelength of light beams. An optical system allows a light beam generated from any one of the first and second light sources to be selectively irradiated onto the optical disc and have an aperture number controller allowing the number of aperture of a light beam to have a different value. A photo detector detects the light beam reflected from the optical disc to be accessed to convert the same into an electrical signal. The apparatus is capable of accessing three types of optical discs different in the layout condition by utilizing an appropriate combination of a wavelength of the light beam with the number of aperture.

Abstract: The present invention relates to an optical pickup apparatus enabling to reproduce/record data of different kinds of disks in different thicknesses, using one single optical pickup. The optical pickup apparatus includes two objective lens, in which one objective lens has an incident plane and an outgoing plant formed of a flat plane at a designated radius domain from an optical axis, thereby preventing spherical aberration caused by the difference of the thickness between different kinds of disks.

Abstract: An optical pickup apparatus that can adaptive for a plurality types of optical discs different in the layout condition such as a recording density, etc. and an optical recording/reproducing apparatus employing the optical pickup apparatus. In the optical pickup apparatus, first and second light sources generate a different wavelength of light beams. An optical system allows a light beam generated from any one of the first and second light sources to be selectively irradiated onto the optical disc and have an aperture number controller allowing the number of aperture of a light beam to have a different value. A photo detector detects the light beam reflected from the optical disc to be accessed to convert the same into an electrical signal. The apparatus is capable of accessing three types of optical discs different in the layout condition by utilizing an appropriate combination of a wavelength of the light beam with the number of aperture.

Abstract: A tilt detecting apparatus of an information-recording medium having a photo diode for detecting a light reflected from an information-recording medium and outputting a light amount signal according to the detected light amount; and a calculating unit for calculating a radial tilt amount by using the light amount signal, wherein the photodiode is divided into a plurality of cells which are identified as regions according to a light amount of the reflected light, based on which a tilt signal is detected. A portion of the reflected light diffracted at the information-recording medium is detected by using the 8-divided photo diode, the region having a large difference in a light amount by the tilt and the region having a small difference in a light amount by the tilt in view of the characteristic of the reflected light are detected.

Abstract: An optical pickup apparatus that is capable of eliminating a crosstalk component of a high-density optical disc effectively. In the apparatus, a first polarizing phase plate is arranged on a light path of a light-focusing system for irradiating a light beam onto the optical disc. A second polarizing phase plate is arranged on a light path of a light-receiving system for detecting a reflective light from the optical disc. The apparatus is capable of eliminating a crosstalk component optimally by detecting sub-beams separately using the first and second polarizing phase plates consisting of a plurality of phase zones.

Abstract: An optical pickup apparatus that is capable of eliminating a crosstalk component effectively. In the apparatus, a sub-beam for eliminating a crosstalk component is produced by utilizing a polarizing phase plate. The polarizing phase plate is provided with at least two phase zones with a different phase at each side on a basis of the center thereof. According to the apparatus, a position of the sub-beam is easily controlled in accordance with a track pitch of the optical disc by utilizing the polarizing phase plate consisting of a plurality of phase zones, thereby eliminating a crosstalk component optimally.

Abstract: An improved optical pickup apparatus for different discs which is capable of writing and reading a data onto discs having different writing densities and thicknesses by using one optical pickup apparatus and a liquid crystal deflector (LCD) or a Grating Polarizing Beam Splitter (GPBS). The apparatus includes an objective lens for focusing a beam onto optical discs each having different thicknesses, and a numerical aperture control means for selectively passing through a beam in accordance with the thickness of the optical discs, diffracting a portion of the beam, and controlling the numerical aperture of the objective lens.