Abstract: A photo-curable adhesive composition including an oligourethane acrylate in a range of about 10 to about 30% by weight, a reactive monomer-diluent in a range of about 32 to about 46% by weight, a polymeric filler in a range of about 20 to about 30% by weight, a photoinitiator in a range of about 2.5 to about 5.0% by weight, an antioxidant in a range of about 0.005 to about 0.02% by weight, a chlorinated polyvinyl chloride in a range of about 3.0 to about 10%, the chlorinated polyvinyl chloride having a chlorine content of about 62 to about 64% by weight, oxalic acid in a range of about 0.3 to about 2.0% by weight, a thixotropic agent in a range of about 0.5 to about 3.0% by weight, and a plasticizer in a range of about 1.0 to about 10.0% by weight, based on the total weight of the composition.

Abstract: An optical pickup of an optical recording and reproducing apparatus includes a plurality of object lenses used to record and or reproduce information from/to various types of optical recording media of different recording densities; an actuator driving the object lenses in a focusing direction and supporting the object lenses to have rolling during movement in the focusing direction; and a pickup base installed to movably go and return in a radial direction of an optical recording medium, and the actuator forming a predetermined angle with respect to the pickup base.

Abstract: An optical pickup actuator, including a lens holder movably installed on a base, and mounted with an objective lens to transmit an incident light to an optical information recording medium, and a magnetic circuit to independently drive the lens holder in a focusing direction, a tilting direction and a tracking direction, respectively.

Abstract: An optical pickup apparatus according to an embodiment of the present invention, comprises an optical unit for projecting a plurality of wavelengths of light, the light including a celadon light, toward a recording medium and receiving the light reflected from the recording medium to thereby detect an information signal and an error signal, and a compatible objective lens for focusing a light projected from the optical unit to thereby form an optical spot on a recording surface of the recording medium and applying at least three light having different wavelength ranges to be compatibly used for both the high-density and the low-density recording mediums. Accordingly, the optical pickup apparatus is capable of compatibly employing a high-density recording medium, which uses a celadon light and is slimmer than a digital versatile disc (DVD), and at least one low-density recording medium.

Abstract: An optical recording/reproducing apparatus including a plurality of light sources emitting lights with different wavelengths for use in recording/reproducing information onto/from various types of optical recording media of different recording densities, in which at least two lights emitted from the light sources have polarization components orthogonal to each other; an objective lens for focusing a light from each of the light sources to a corresponding optical recording medium; a collimating lens disposed between the light sources and the objective lens for collimating lights from the light sources; a hologram element installed between the collimating lens and the objective lens for refracting a light emitted from one of the light sources, in which the light to be refracted is selected by wavelength and polarization components; and a photodetector receiving a light that is reflected from the corresponding optical recording medium after being focused by the objective lens.

Abstract: A photo-curable adhesive composition includes oligourethane acrylate in a range of about 11 to about 23% by weight, reactive monomer-diluent in a range of about 11 to about 24% by weight, silicate filler in a range of about 50 to about 65% by weight, photoinitiator in a range of about 2.5 to about 5.0% by weight, organic peroxide in a range of about 0.1 to about 0.5% by weight, thixotropic agent in a range of about 0.5 to about 3.5% by weight, antioxidant in a range of about 0.005 to about 0.02% by weight, silane finishing agent in a range of about 0.1 to about 2.5% by weight, and oxalic acid in a range of about 0.5 to about 1.5% by weight, based on the total weight of the composition.

Abstract: A diffraction element for an optical pick-up apparatus is provided that enables more accurate focusing control. The diffraction element for an optical pick-up apparatus is divided into first and second regions, each being formed with a grid pattern in which grids are repeated with a predetermined pitch P. The grid pattern in at least one of the first and second regions is tilted by a predetermined angle with respect to a virtual line VL substantially perpendicular to a division line DL that divides the first and second regions.

Abstract: An optical pickup which is compatible with at least one high density recording medium that uses a blue-violet beam and at least one lower density recording medium, the optical pickup including: an optical unit to selectively emit one of a plurality of beams with different wavelengths onto one of the at least one high density recording medium and the at least one lower density recording medium, and to receive the respective beam reflected from the respective recording medium; and a holographic objective lens to focus the respective beams emitted by the optical unit on a recording surface of the respective recording medium, the holographic objective lens including a first holographic lens region and a second holographic lens region located inside the first holographic lens region, wherein holographic patterns of the first and second holographic lens regions respectively produce a first effective numerical aperture (NA) for the at least one high density recording medium and at least one additional effective NA s

Abstract: An actuator for an optical pick-up, including: a holder fixed to a base; a bobbin capable of accommodating a plurality of objective lenses for recording and/or reproducing information onto and/or from optical discs with different recording densities; a suspension for connecting the bobbin and the holder, and supporting the bobbin to be movable; and a magnetic circuit for driving the bobbin in focusing, tilting, and tracking directions, wherein the magnetic circuit includes a plurality of focusing/tilting coils installed in the bobbin to be in correspondence to the plurality of lenses, and driving the bobbin in at least one of focusing and tilting directions; a plurality of magnets having the focusing/tilting coils therebetween, in which same polarities of the magnets make one pair; and tracking coils supported by the bobbin, and generating a driving force to drive the bobbin in the tracking direction.

Abstract: An optical pickup device is provided with a plurality of object lens corresponding to various kinds of optical discs having different recording densities, in which the structure of the optical pickup device is simplified and the size of the optical pickup device is minimized. The optical pickup device comprises a bobbin including an upper surface, at which first and second object lenses are mounted, an opened lower surface, and a first and second side surfaces supported by a supporting unit, the first and second side surfaces being opposite to each other, a first focus coil and a first tracking coil mounted at a third side surface of the bobbin, a second focus coil and a second tracking coil mounted at a fourth side surface of the bobbin, which is opposite to the third side surface, and magnets disposed opposite to the first and second focus coils and the first and second tracking coils.

Abstract: An object lens arranged on a light proceeding path to focus light on a recording medium includes a first surface that is an incident surface on which light is incident, a second surface from which light exits to be focused on the recording medium, and a diffractive optical element disposed on at least one of the first and second surfaces and which has a refractivity of fD/f<5, fD being a focus distance of the diffractive optical element and f being a focal distance of the object lens. The object lens has a numerical aperture of 0.75 or greater.

Abstract: An optical pickup to improve countermeasure capability of a disc by allowing polarized light of a spot on the disc to become elliptically polarized light includes a light source to emit semiconductor laser light, an objective lens to condense the light emitted from the light source and form an optical spot on a disc, and a wave plate which is rotated such that the spot formed on the disc becomes elliptically polarized light.

Abstract: A compatible optical pickup includes a light source which emits a first light beam having a wavelength for a first recording medium; a twin light source which emits second and third light beams respectively having wavelengths for second and third recording media; a first objective lens which condenses the first light beam to form a light spot for recording and/or reproduction of the first recording medium; a second objective lens which condenses the second and third light beams to form light spots for recording and/or reproduction of the second and third recording media; an actuator which drives the first and second objective lenses; a first photo-detector which receives the first light beam reflected from a recording medium to detect an information signal and/or an error signal; and a second photo-detector which receives the second and third light beams reflected from a recording medium to detect information signals and/or error signals.

Abstract: An optical pickup apparatus for reading and writing information from and to optical data media in different formats and a method thereof are provided. The optical pickup apparatus comprises a twin laser diode (Twin LD), a diffraction element for dividing a laser beam incident on a data medium into five beams, and an optical detector for focusing a laser beam reflected from the data medium to detect an information signal and signals for carrying out servo controls. The divided beams are focused on a predetermined location in based on a data medium format, and the beam reflected from the data medium is received on and detected from the corresponding photodiodes of the optical detector so that a focus error signal and a tracking error signal are generated.

Abstract: An optical pickup which can remove birefringence due to the non-uniformity of an optical recording medium by using a polarization beam splitter. The optical pickup includes a light source emitting a laser beam, a beam splitter reflecting part of incident light and straight transmitting the remaining light to change a proceeding path of the incident light, an objective lens focusing the incident light passed through the beam splitter to form a light spot on an optical recording medium, a polarization beam splitter arranged on an optical path between the beam splitter and the objective lens for transmitting light having one polarization and reflecting light having a different polarization.

Abstract: An optical pickup apparatus includes a first objective lens having a low numerical aperture (NA) suitable for a low density recording medium, a second objective lens having a high NA suitable for a high density recording medium, a first light source that emits short wavelength light which is focused onto an optical recording medium by the first and second objective lenses, a first photodetector that receives a returning reflected light from the optical recording medium, and a first optical path converter for selectively guiding part of the light emitted from the first light source towards the first or the second objective lens, and guiding the reflected light towards the first photodetector.

Abstract: An optical pickup includes an optical module that detects an information signal and/or an error signal by radiating light to a recording medium and receives light reflected by the recording medium. The optical module includes a light source; an optical path changer that changes a path of light emitted from the light source; a main photodetector that receives light that is reflected off a recording medium back to the optical module to detect an information signal and/or an error signal; and a hologram element that generates an astigmatism of the light incident onto the optical module. Since most optical elements of the optical pickup except an objective lens are packaged in the optical module, the entire structure of the optical pickup can be simplified and the number of bonding points for fixing the optical elements of the optical pickup on a base can be reduced.

Abstract: A method of reproducing information from an optical disc, and an optical disc reproducing apparatus using the method, including reproducing information from an optical disc having a plurality of regions with differing physical specifications, the information is read using optical beams having differing spot sizes in regions of the optical disc having differing physical specifications. The method enables the optical disc having the regions with differing physical specifications to stably reproduce information from all regions of the optical disc by minimizing regional reproduction performance differences caused in the reproduction process.

Abstract: Disclosed is an optical pickup including a polarization holographic optical element (HOE) and a photodetector. The optical pickup includes a light source, an optical path changer, an objective lens, a polarization HOE, and a photodetector. The polarization HOE has a pattern designed to generate different astigmatisms in the left and right halves of the polarization HOE in a tangential direction and to divide plus and minus first-order beams in a radial direction. The photodetector includes a first light-receiving portion receiving a zero-order beam and second and third light-receiving portion that are disposed on either side of the first light-receiving portion in the tangential direction and respectively receive the plus and minus first-order beams.

Abstract: An object lens arranged on a light proceeding path to focus light on a recording medium includes a first surface that is an incident surface on which light is incident, a second surface from which light exits to be focused on the recording medium, and a diffractive optical element disposed on at least one of the first and second surfaces and which has a refractivity of fD/f<5, fD being a focus distance of the diffractive optical element and f being a focal distance of the object lens. The object lens has a numerical aperture of 0.75 or greater.