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. Since the light path with respect to the field angle and the beam shift is adjusted by moving and/or rotating the light emitting point of the laser beam source with respect to the light axis of the collimating lens, the size of the optical pickup becomes smaller. Further, since the collimating lens and the light source are fixed to the respective structures, the light path is controlled regardless of the focal distance of the collimating lens. Accordingly, if the focal distance of the collimating lens has to be lengthened, the beam shift and the field angle can be precisely adjusted without enlarging the optical pickup.
Abstract:
An optical pickup device employing a signal detection unit including a hologram element having a plurality of pattern regions for diffracting and/or focusing light reflected and incident from a recording medium, a photodetector having a plurality of light receiving regions for receiving and photoelectrically converting the light diffracted by the hologram element and a signal operation unit for generating a focus error signal and/or a track error signal from a signal detected from the photodetector. The optical pickup device can implement a stable servo operation even at deviations of the photodetector, a change in the wavelength of light emitted from the light source, and/or shift of focusing means such as an objective lens, and can record and/or reproduce high-density information on/from the recording medium.
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:
A lens device which can be used as an objective lens in an optical pickup apparatus includes an objective lens provided along a light path facing a disc and having a predetermined effective diameter, and light controlling means provided along the light path for controlling the light in an intermediate region between near and far axes of an incident light beam, thus providing a simplified and inexpensive device for using discs of differing thickness in a single disc drive, by reducing the spherical aberration effect.
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.2 matrix arrangement, for diffracting light incident from the sensing lens in different directions, wherein the first through fourth pattern regions a, b, c and d are formed such that a first focus of the +1st-order diffracted beams diffracted by the first and third pattern regions is relatively farther from the sensing lens than a second focus of the +1st-order diffracted beams diffracted by the second and fourth pattern regions, a photodetector disposed between the first and second focuses and having first through fourth light receiving units, for receiving the beams diffracted by the first through fourth pattern regions and independently photoelectrically converting the same, and a signal operation unit for detecting a focus error signal and/or a track error signal from detection signals of the light receiving parts. The error signal detecting apparatus can suppress generation of an offset of a focus error signal due to a change in the wavelength of a light source and an offsets of the focus error signal and track offset signal due to deviations of the photodetector.
Abstract:
A lens device which can be used as an objective lens in an optical pickup apparatus includes an objective lens provided along a light path facing a disc and having a predetermined effective diameter, and light controlling means provided along the light path for controlling the light in an intermediate region between near and far axes of an incident light beam, thus providing a simplified and inexpensive device for using discs of differing thickness in a single disc drive, by reducing the spherical aberration effect.
Abstract:
A semiconductor laser for generating a laser beam and an optical pickup for recording/reproducing information using the semiconductor laser as an optical source are provided. The semiconductor laser includes an aperture member on an emitting end thereof to perform high-density memory recording/reproducing through the reduction of an optical spot. The aperture has a hole whose diameter is smaller than the width of the active region of the semiconductor laser, to thereby restrictively emit the laser beam via the hole so that the optical spot formed on an optical disk is reduced. Thus, high-density memory recording/reproducing, which is useful for miniaturized information processors, can be realized.
Abstract:
A lens device which can be used as an objective lens in an optical pickup apparatus includes an objective lens provided along a light path facing a disc and having a predetermined effective diameter, and light controlling means provided along the light path for controlling the light in an intermediate region between near and far axes of an incident light beam, thus providing a simplified and inexpensive device for using discs of differing thickness in a single disc drive, by reducing the spherical aberration effect.
Abstract:
A lens device which can be used as an objective lens in an optical pickup apparatus includes an objective lens provided along a light path facing a disc and having a predetermined effective diameter, and light controlling means provided along the light path for controlling the light in an intermediate region between near and far axes of an incident light beam, thus providing a simplified and inexpensive device for using discs of differing thickness in a single disc drive, by reducing the spherical aberration effect.
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. The projection-type image display apparatus includes a light source; a color separation unit separating incident rays according to predetermined wavelengths, and directing the separated rays at different angles; a lens array dividing the rays separated by the color separation unit into predetermined pixels; a driving portion driving the lens array to change the proceeding paths of the color rays; a polarizing beam splitter changing a proceeding path of incident rays depending on a direction of polarization; a reflection-type display device producing a color image using the rays entering via the polarizing beam splitter, and reflecting the color image toward the polarizing beam splitter; and a projection lens unit magnifying and projecting an incident image onto a screen. In addition, the projection-type image display apparatus may comprise. Alternative designs include a transmission-type display device in place of the reflection-type display device and a deflector changing the proceeding paths of the individual color rays separated by the color separation unit instead of the driving portion.