摘要:
An optical pickup for all optical disk having multiple recording layers is provided to exactly control a focal position according to the thickness of optical disk, by separately controlling focal positions on each recording layer, wherein a Fresnel lens for diffracting an optical beam generated from an optical source and an objective lens for focusing the diffracted beam are separately located, and focus driving coils are included for separately driving the Fresnel lens and objective lens by using a signal detected by an optical detector. As the interval between the Fresnel lens and objective lens is varied, the interval between focal points formed on each recording layer is also varied. Thus, the focal positions formed on each recording layer can be exactly controlled according to the thickness of optical disk. Therefore, information can be clearly reproduced without interference by simultaneously scanning each recording layer while exactly controlling the focal positions.
摘要:
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.
摘要:
An optical pickup device which can obtain a stable reproduction signal by increasing the numerical aperture of an objective lens includes an objective lens facing a disc, a light source for radiating light to the disc via the objective lens, a beam splitter provided between the light source and objective lens for directing the light reflected from the disc in a path different from that of the light travelled from the light source, a photodetector for detecting the light reflected from the disc and travelled via the beam splitter, and a diaphragm provided between the beam splitter and light source and having a predetermined numerical aperture.
摘要:
A method and apparatus for high-density reproduction of information recorded on an optical disk by increasing the optical resolution during reproduction. The apparatus focuses an optical beam reflected from the optical disk using a lens, and receives the focused reflected optical beam using a photodetector having an optical area whose width is smaller than the diameter of an optical spot formed thereon. As a result, jitter caused by interfering light, that is, light reflected from the circumference such as a recording portion adjacent to the optical disk, can be solved. Also, high-density reproduction can be performed by increasing the optical resolution during reproduction. The apparatus can be applied to an optical pickup for high-density recording.
摘要:
A reproducing/recording optical pickup compatible with discs having different thicknesses includes a transparent plate having a central portion formed with a diffraction grating pattern for diffracting the light travelling from the light source to the objective lens, and a transparent portion through which the light passes, and a photodetector having first and second light receiving portions. The zero-order transmitted light and the passing light are focused using all regions of the aperture of the objective lens with respect to a thin disc. The positive first-order diffracted light diffracted by the diffraction grating pattern of the transparent plate is focused onto a thick disc by partial regions of the objective lens. Then, the reflected lights thereof are detected by the first and second light receiving portions, respectively. Because signals for reproduction and servo for each disc are detected as the detection signals of the first and second light receiving portions, stable servo and noiseless reproduction are possible, irrespective of the thickness of the disc used.
摘要:
In an optical pickup, a focus error detector for detecting a focus error of an objective lens for an optical disk includes a focusing lens for focusing the reflected light of the optical disk, a diffraction optical device for diffracting the reflected light focused by the focusing lens into two light rays, two bi-segmented photo-detectors for receiving the two split light rays, respectively, and a circuit for outputting a desired focus error signal from the signal detected from the photo-detectors. The circuit outputs a pure focus error signal without errors created by the deviation of the light amount in the photo-detectors due to the tilt or shift of the reflected light, thereby contributing to the stable operation and miniaturization of the optical pickup.
摘要:
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.
摘要:
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.
摘要:
In detecting a focus error for an optical pickup, an inverse image generator for generating inverse images onto a light beam reflected from an optical disk is used in a focus error detecting method and apparatus thereof. The inverse image generator is composed of a semi-transmissive plane for splitting a light beam into first and second light beams, first and second prisms for inverting the phase of the second light beam, and third and fourth prisms for synthesizing the phase-inverted second light beam with the first light beam. Also, the inverse image generator has two quadrant wave plates, a polarization plane and light synthesizing plane for preventing a light loss. Since the errors due to an optical axis variation is eliminated from the focus error signal detected from the synthetic light beam radiated by the inverse generator, the optical pickup can be driven with stability.
摘要:
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.