Goldstar, Co., Ltd.

Lg Electronics Inc.

Keun Y Yang

Sung Woo Noh

Jong Uk Bu

Eun Jin Kim

Holographic memory including a plurality of HOEs stacked in a vertical direction for two dimensional addressing of a recording medium for increasing a recording capacity and improving productivity and cost.

Holographic memory

A light source module with two wavelengths that is adapted to generate laser beams different in wavelength. In the light source module, a hologram optical element (HOE) is used to allow a first laser beam generated at a first light source and a second laser beam generated at a second light source to progress along same path. The HOE diffracts the second laser beam to change a progressive path of the second laser beam into that of the first laser beam. The first light source generates the first laser beam having a different wavelength from the second laser beam generated at the second light source.

Optical source module with two wavelengths and optical pickup apparatus

A different wavelength type of optical source module which generates light beams different in wavelength. In the optical source module, laser diodes are provided to be opposed to each of reflective films which is arranged to make a shape of a mountain. These respective laser diodes generates laser light beams different in wavelength. The light beams generated at the laser diodes are reflected by the reflective films at a right angle to progress along the same path.

Optical source module for generating beams with different wavelengths

An annular shutter mirror which can selectively shut off a part of light beams progressing toward a target in the progressing direction thereof. The annular shutter mirror utilizes a fixed reflection face to reflect an incident light beam at a constant angle in accordance with an incident angle of the incident light beam. Around the periphery of the fixed reflection face, at least one flexible reflection face is formed in a shape of annular band. This at least one flexible reflection face selectively reflects an incident light beam at an angle different from a reflective angle of the fixed reflection area in accordance with an application condition of an electrical field.

Annular shutter mirror

Disclosed are a hologram unit of an optical pickup which has a main hologram and auxiliary alignment holograms around the main hologram thereof and a method of attaching a hologram plate of the optical pickup comprising the steps of: illuminating an object with an LD; forming an LD radiant point on a monitor through a microscopic lens, and a plurality of radiant points around the LD radiant point by auxiliary alignment holograms; and aligning the LD with the hologram plate by moving the hologram plate so as to form the LD radiant point in the center of the plurality of radiant points.

Hologram unit of optical pickup and method of attaching hologram plate

An objective lens having a first surface and a second surface, includes a first face formed on the first surface, a second face formed on the second surface, and a third face formed on one of the first and second surfaces. The first, second, and third faces are adapted in such a way that the objective lens has at least two focal lengths.

Objective lens

An optical pickup system capable of recording/reading out information on/from a mini disc or magneto-optical disc includes a polarized beam splitter (PBS) for fully reflecting beams of S-wave component from a laser diode or reflected from the disc while partially reflecting and partially transmitting beams of P-wave component, a reflection mirror placed between the PBS and disc for reflecting the beams transmitted through the PBS toward the disc while reflecting the beams reflected from the disc toward the PBS, a first photodetector having plural split areas for detecting a focus error and a tracking error according to the beams focusing on respective split areas, a hologram element for allowing three beams from a grating to be incident to the PBS or diffracting the beams of P-wave component transmitted through the PBS to focus the diffracted beams on the first photodetector, a second photodetector having six split areas for detecting the information recorded on the disc according to the beams focusing on respective split areas thereof, and a Wollaston prism placed between the PBS and second photodetector for separating mixed beams of P-wave and S-wave components from the PBS to allow the separated beams to be incident to the second photodetector, thereby decreasing the number of optical elements to improve readout speed of the information on the disc and simplifying the structure of the optical pickup system to reduce manufacturing cost.

Optical pickup system

An optical pickup device using hologram optical elements, the pickup device including a laser diode and, a hologram glass plate diffracting a laser beam emitted from the laser diode and dividing and condensing the laser beam reflected by an optical disc. The hologram glass plate is arranged at the front of the laser source while being spaced apart from the laser diode by a predetermined distance and is provided with four holograms. A collimator is arranged at the front of the hologram glass plate and changes the laser beam emitted from the laser source as well as the laser beam reflected by the optical disc into a parallel beam. An objective lens focuses the parallel laser beam from the collimator on the optical disc. A pair of focusing photo detectors and a pair of tracking photo detectors are also provided at the front of the laser diode and detect the laser beams diffracted and condensed by the holograms of the hologram glass plate in the form of data reading signals. In order to compensate a focusing error and a tracking error, an error compensating actuator is arranged at a side of the objective lens and moves the objective lens in accordance with error signals detected by the focusing and tracking photo detectors.

Optical pickup device

An optical pickup system capable of improving productivity by facilitating the arrangement and assembly of components thereof and preventing an error caused by wavelength variation of a laser beam includes a laser diode used as a light source, a grating for classifying a beam from the laser diode into three diffracted lights of zero, +first and -first orders, an objective lens placed the grating and an optical disc for focusing the three diffracted lights passed through the grating on the optical disc while receiving the lights reflected from the optical disc, a photodetector divided-by-five formed of five split areas partitioned in the longitudinal direction to be arranged side by side in the sequence of fourth, first, second, third and fifth split areas to receive the lights reflected from the optical disc focusing on the respective split areas for detecting a focus error and a tracking error and reading out information recorded on the optical disc, and a hologram element divided-by-two formed of a first hologram of which reference light position is a light-emitting point of the laser diode and an object light position is set before passing the photodetector divided-by-five and a second hologram of which reference light position is the light-emitting point of the laser diode and an object light position is set after passing the photodetector divided-by-five, for diffracting the reflected lights from the optical disc prior to passing the photodetector divided-by-five, thereby being applicable to optical apparatuses such as CDPs, VDPs, ODPs and MDPs.

Optical pickup system with five longitudinal splitted detection areas to

An optical pickup system simply formed to improve readout speed and reduce manufacturing cost having a semiconductor laser light source, a polarizing beam splitter (PBS), a collimator lens for changing the laser beam into parallel beams, a reflection mirror, an objective lens, a photodetector divided-by-six for detecting tracking and focus errors, a hologram device, a bisectional photodetector, a Wollaston prism for separating a beam into P-wave and S-wave components from a mixed beam of P-wave and S-wave components from the PBS, and a focusing lens for focusing the P-wave and S-wave component beams separated by the Wollaston prism onto two sections of the bisectional photodetector.

Optical pickup system for reading or writing information on disk using

This invention relates to an optical pickup system which can detect focus errors and tracking errors without using diffraction grating. The optical pickup system comprises a laser diode for emitting laser beams, an objective lens for focusing the laser beam from the laser diode onto an optical disc, a two division hologram positioned between the laser diode and the objective lens for diffracting beams after separating a reflected beam reflected at the optical disc and passed through the objective lens into a first laser beam and a second laser beam along an tangential line to a track of the optical disc, and a four division photodetector for focusing the two laser beams diffracted by the two division hologram.

Optical pick-up system and method for accurately reading information recorded on an optical disc. The invention makes it possible to determine the kind of an error occurring upon reading information recorded on an optical disc by light beams from a light source, by using error detectors, and to correct accurately the error by driving a focusing lens, thereby capable of rapidly correcting errors such as tracking/focusing errors, providing a light and compact construction and improving a reliance, so as to solve problems of a high sensitivity to variations, a poor assembling ability, a bulky construction and a degraded reliance, encountered in optical devices which have been generally used for reading information recorded on optical discs.

Optical pick-up system with servo using reflection plate having aperture

An optical pickup system using a holographic optical element for achieving miniaturization and lightness. This optical pickup system comprises a semiconductor laser for generating a laser beam, an objective lens for focusing the laser beam emitted from the semiconductor laser on an optical disk, a quadrant hologram for diffracting and condensing the laser beam, reflected by the optical disc and transmitted through the objective lens, to a quadrant photo detector, and the quadrant photo detector detecting the laser beam, diffracted and condensed by the quadrant hologram, and reading data recorded on the optical disc. The quadrant hologram and the quadrant photo detector are arranged in such a manner that the optical paths of the first to fourth hologram members of the quadrant hologram pass through the centers of the first, third, second and fourth photo detecting members of the quadrant photo detector, respectively. The laser beam is condensed by the first hologram member after passing through the first photo detecting member, condensed by the second hologram member before passing through the third photo detecting member, condensed by the third hologram member before passing through the second photo detecting member, and condensed by the fourth hologram member after passing through the fourth photo detecting member.

Optical pickup apparatus having a quadrant hologram and a quadrant photo

An optical pick-up device capable of accurately detecting focus errors, tracking errors, magneto-optic signals and pit signals recorded on an optical disc by use of a dichotomous hologram and decreasing the number of optical elements used, thereby achieving a lightness and an improvement in reading rate. The optical pick-up device includes a laser transmission and receipt error detecting unit for detecting an error present at the optical disc, based on size of reproduced beams corresponding to a part of P-wave components of beams reflected depending on optical information recorded on the optical disc, a polarized-beam splitting unit for reflecting all of beams emerging from the collimator lens while being S-polarized and a part of beams emerging from the collimator lens while being P-polarized, and transmitting the remaining part of the P-polarized beams to focus them onto the optical disc via information record/reproduction processing unit, the polarized-beam splitting unit also serving to transmit and reflect beams reflected by the optical disc, and an optical information reading unit for reading the information recorded on the optical disc, based on signals respectively indicative of the sum of and the difference between all the S-wave components and the part of P-wave components of the beams received from the polarized-beam splitting unit.

Optical pick-up device with error detection using P-wave

An optical pickup system for generating information signals recorded on a recording medium includes a semiconductor laser generating source for generating and emitting a laser beam, an object lens for condensing the generated laser beam for an optical disc and receiving the laser beam reflected by an optical disc, a beam separator for changing a forwarding direction of the laser beam reflected by an object lens reflected by the optical disc, a prism for directing a portion of the beam to a pair of photo detector units provided on the prism and for forwarding the remainder of said laser beam in the same direction it was travelling when first incident on the prism, a condensing lens for condensing the laser beam reflected by the prism, and a focusing error compensating means for compensating two signals to be zero by an actuator.

Growing community of inventors

Seoul, South Korea

Keun Y Yang