Abstract: A projection-type image display apparatus having a structure adapted so that the efficiency of the use of light and resolving power thereof can be enhanced is disclosed.

Abstract: A compatible optical pickup capable of recording or reproducing information on or from compact disc (CD) family media such as CD rewritable (CD-RW) and digital versatile disc (DVD) by adopting a stepped planar lens having a plurality of gratings.

Abstract: An optical recording/pickup head compatible with a CD-R and a DVD transfers a first light beam of 650 nm wavelength for a DVD and a second light beam having a wavelength of 780 nm for a CD-R, which are respectively emitted from a first light source and a second light source, to an objective lens using first and second beam splitters having polarized light beam splitting characteristics which are varied according to a wavelength. The objective lens focuses the transferred first and second light beams on the information recording surfaces of the DVD and a CD-R, respectively. The first and second light beams reflected from the information recording surfaces of the DVD and the CD-R, respectively, are transferred to first and second photodetectors by the first and second beam splitters, respectively. The first and second photodetectors detect information from the first and second light beams incident from the first and second beam splitters, respectively.

Abstract: An optical pickup apparatus compatible with at least two types of optical recording media, using light beams having respective different wavelengths for recording and reading information, the optical pickup apparatus including two laser light sources to emit light beams having the different wavelengths, respectively, a holographic lens, including a holographic ring, to transmittal of the light beams emitted from the laser light sources in an inner region of the holographic ring, and diffracting a specific light beam among the light beams emitted from the laser light sources in an outer region relative to the inner region, an objective lens to focus the light beams passed through the holographic ring lens on the respective information recording surfaces of the two types of the optical recording media, optical elements to alter optical paths of the light beams reflected from the information recording surfaces of the optical recording media; and two photodetectors to individually detect optical information from

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: A recording/reproducing apparatus includes an optical pickup device having an optical phase plate which is compatible with optical recording mediums having different thicknesses, and an optical signal processing device processes information read from the optical recording mediums and processes information to be recorded thereon using the optical pickup device.

Abstract: An optical pickup apparatus having compatibility with a recodable compact disk (CD-R) and a digital video disk (DVD), which uses a wavelength of one of a first light beam and a second light beam according to the recording medium to be used. In the optical pickup apparatus, laser light sources emit a first light beam having a relatively shorter wavelength for the DVD and a second light beam having a longer wavelength for the CD-R, respectively. An objective lens has a predetermined focal length in accordance with the position of an information recording surface in the DVD. An optical path control unit controls the path of light beams so that the light beam emitted from one of the laser light sources is directed to the objective lens and the light output from the objective lens is directed to the optical detection unit.

Abstract: An optical focusing system which uses a light beam emitted from a light source, includes a refractive surface on one side of the optical focusing system and having a first radius of curvature, a first reflection surface on the above one side, surrounding the refractive surface and having a second radius of curvature being different from the first radius of curvature, a transparent beam focusing surface on the other side of the optical focusing system, and a second reflection surface on the above other side and surrounding the beam focusing surface. The refractive surface refracts an incident light beam, the second reflection surface reflects a light beam refracted by the refractive surface toward the first reflection surface, and the first reflection surface focuses a laser light beam reflected from the second reflection surface on the beam focusing surface as a focused beam spot. The optical focusing system can be used in an optical pickup.

Abstract: A recording/reproducing apparatus having an optical pickup device which is efficient in light use having little spherical aberration.

Abstract: An optical pickup includes a light source emitting a laser beam and an optical path changing unit altering a traveling path of an incident beam. An objective lens, disposed on an optical path between the optical path changing unit and an optical disk, focuses the incident beam from the light source to form a light spot on the optical disk of the objective lens. The optical pickup further includes a photodetector and an detecting-correcting unit, arranged on the optical path between the optical path changing unit and the objective lens, performing at least one of detecting the thickness of the optical disk and correcting aberration caused by thickness variations of the optical disk. The objective lens includes a first transmitting portion divergently transmitting an incident beam, where the first transmitting portion is at a relatively near-axis region from an optical axis of the objective lens.

Abstract: A recording/reproducing apparatus having an optical pickup device which is efficient in light use having little spherical aberration.

Abstract: A fast responding optical modulating device for a high-density recording using in an optical pickup includes a light source, an optical modulator and a pair of lenses. The pair of lenses are so arranged that the distance between the lenses is shorter than the sum of each focal length of the lenses. The device can adjust an optical spot size at the center of the optical modulator by changing the position of the lenses without altering the whole length between the light source and optical modulator. Therefore, the device can increase the rise time as desired and the optical efficiency in optical modulation for high-density recording which uses a short wavelength light source, and moreover, has an effect of simplifying the high-density recording.

Abstract: An optical pickup for recording/reproduction. The optical pickup includes a light source unit including a light emitting diode (LED) to emit light and a waveguide to condense the light emitted from the LED; a collimating lens to collimate the light emitted from the waveguide; an objective lens to condense the light passed through the collimating lens to form a light spot on the recording surface of a recording medium; a light path changing unit arranged on an optical path between the collimating lens and the objective lens, to change a traveling path of the incident light; and a photodetector to receive the light incident via the objective lens and the light path changing unit after being reflected from the recording medium.

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: An optical pickup apparatus having compatibility with a recodable compact disk (CD-R) and a digital video disk (DVD), which uses a wavelength of one of a first light beam and a second light beam according to the recording medium to be used. In the optical pickup apparatus, laser light sources emit a first light beam having a relatively shorter wavelength for the DVD and a second light beam having a longer wavelength for the CD-R, respectively. An objective lens has a predetermined focal length in accordance with the position of an information recording surface in the DVD. An optical path control unit controls the path of light beams so that the light beam emitted from one of the laser light sources is directed to the objective lens and the light output from the objective lens is directed to the optical detection unit.

Abstract: An optical pickup apparatus having compatibility with a recodable compact disk (CD-R) and a digital video disk (DVD), which uses a wavelength of one of a first light beam and a second light beam according to the recording medium to be used. In the optical pickup apparatus, laser light sources emit a first light beam having a relatively shorter wavelength for the DVD and a second light beam having a longer wavelength for the CD-R, respectively. An objective lens has a predetermined focal length in accordance with the position of an information recording surface in the DVD. An optical path control unit controls the path of light beams so that the light beam emitted from one of the laser light sources is directed to the objective lens and the light output from the objective lens is directed to the optical detection unit.

Abstract: An optical pickup using a light-emitting diode (LED), which is capable of forming a light spot of an appropriate size for high-density recording/reproduction. The optical pickup includes a light-emitting diode (LED) to generate and emit light; a condensing unit to condense the light emitted from the LED; an optical filter to selectively transmit a predetermined wavelength of the light emitted from the LED; a spatial filter having a pin-hole, to limit a transmission range of the light condensed by the condensing unit; and a collimating lens to condense the divergent light passed through the spatial filter to form a parallel light. The parallel light is directed by a beam splitter toward an objective lens which focuses the parallel light on an optical disk. The light reflected from the optical disk is received by a photodetector.

Abstract: An optical pickup compatible with a plurality of optical recording media each using light of a different wavelength. The optical pickup includes at least one light source, an objective lens having a function of focusing light emitted from the light source into the optimal light spot on an information recording surface of one of the plurality of the optical recording media, and a light detector to detect light transmitted through the objective lens after being reflected from the information recording surface of the optical recording medium on which the light spot is formed. The objective lens has an inner area, an annular lens area and an outer area such that the annular lens area divides the inner area from the outer area and has a ring shape centered at a vertex.

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: An optical pickup device which is efficient in light use having little spherical aberration. The optical pickup device of an optical pickup includes an objective lens, disposed opposite a disk, having a light passing region divided into central, intermediate and periphery regions corresponding to a near axis area, an intermediate axis area and a far axis area of incident light, where the curvature of the central and peripheral regions is optimized for a thin disk and that of the intermediate region is optimized for a thick disk; a light source irradiating light toward a disk through the objective lens; a photo detector for detecting light reflected from the disk; and a beam splitter, disposed between the objective lens and the light source, for transmitting light from the light source toward the objective lens and for diffracting light reflected from the disks toward the photo detector.