摘要:
An optical pickup has a semiconductor laser, a diffractive optical element that has first diffraction regions and second diffraction regions and diffracts a beam emitted by the semiconductor laser, an objective lens that focuses the diffracted beam on an optical disc, and a detection unit that detects a tracking error signal using the diffracted beam reflected by the optical disc. When a zero order diffraction beam is focused on the optical disc, a first order diffraction beam is diffracted by the first diffraction regions to be focused at a position between the objective lens and the optical disc, and diffracted by the second diffraction regions to be focused at a position beyond the optical disc. The first order diffraction beam has a beam width that, on the optical disc in a radial direction thereof, is two times or greater a track pitch of the optical disc.
摘要:
An optical pickup wherein a main beam and at least two sub-beams are collected on a disc and a tracking error signal is detected from push pull signals generated from each beam. A phase of the push pull signal generated from the first sub-beam is shifted from a phase of the push pull signal generated from the second sub-beam by substantially 180°. A phase difference is given to a part of the first sub-beam (10) and a part of the second sub-beam (11) by a diffraction optical element (2) which generates the first sub-beam (10) and the second sub-beam (11).
摘要:
An optical semiconductor device both capable of recording and reproducing information with respect to plural optical disks having different track pitches and capable of shortening an assembly time and achieving a cost reduction without the need to make a highly-precise assembly adjustment is provided. An optical semiconductor device is constituted by a semiconductor laser element, an emitted light beam branching element for branching a light beam emitted from the semiconductor laser element into a main beam and a plurality of sub beams, an objective lens for focusing the main beam and the sub beams onto an optical disk, and a light-receiving element for signal detection for detecting each of the main beam and the sub beams reflected by the optical disk. Further, a light distribution of the sub beams branched by the emitted light beam branching element has a shape equal to or narrower in an optical disk radial direction than a shape obtained by bisecting a light distribution of the main beam when the sub beams enter the objective lens.
摘要:
An optical pickup has a semiconductor laser, a diffractive optical element that has first diffraction regions and second diffraction regions and diffracts a beam emitted by the semiconductor laser, an objective lens that focuses the diffracted beam on an optical disc, and a detection unit that detects a tracking error signal using the diffracted beam reflected by the optical disc. When a zero order diffraction beam is focused on the optical disc, a first order diffraction beam is diffracted by the first diffraction regions to be focused at a position between the objective lens and the optical disc, and diffracted by the second diffraction regions to be focused at a position beyond the optical disc. The first order diffraction beam has a beam width that, on the optical disc in a radial direction thereof, is two times or greater a track pitch of the optical disc.
摘要:
An optical pickup device includes a diffraction grating for separating a light beam from a semiconductor laser into at least three light beams. The diffraction grating is partitioned into five areas each having a given periodic structure: a first area; a second area adjacent to the first area in a first direction; a third area adjacent to the first and second areas in a second direction; a fourth area sandwiching the third area with the first area; and a fifth area adjacent to the fourth area in the first direction and sandwiching the third area with the second area. The phase of the periodic structure of each of the first and fifth areas is ahead of that of the third area by substantially 90°. The phase of the periodic structure of each of the second and fourth areas is behind that of the third area by substantially 90°.
摘要:
An optical pickup device includes a diffraction grating for separating a light beam from a semiconductor laser into at least three light beams. The diffraction grating is partitioned into five areas each having a given periodic structure: a first area; a second area adjacent to the first area in a first direction; a third area adjacent to the first and second areas in a second direction; a fourth area sandwiching the third area with the first area; and a fifth area adjacent to the fourth area in the first direction and sandwiching the third area with the second area. The phase of the periodic structure of each of the first and fifth areas is ahead of that of the third area by substantially 90°. The phase of the periodic structure of each of the second and fourth areas is behind that of the third area by substantially 90°.
摘要:
An optical pickup device includes a first semiconductor laser device, a second semiconductor laser device, a third semiconductor laser device, a first diffraction grating, a beam splitter, a quarter-wave plate, a collimator lens, a first polarization hologram device, a second polarization hologram device and a third polarization hologram device. The second semiconductor laser device and the third semiconductor laser device are provided in a light source/detection unit together with a second diffraction grating and photo-receiver groups, so as to make the optical pickup device compact.
摘要:
An optical pickup apparatus for use with a semiconductor laser which outputs a light beam, the optical pickup apparatus has; a diffraction grating for diffracting the light beam into diffracted light; a collimator lens for rendering the diffracted light diffracted by the diffraction grating as a parallel beam; an objective lens for focusing the parallel beam towards an optical information recording medium; a hologram element for diffracting return light reflected from the optical information recording medium; a plurality of light receiving elements for receiving the diffracted light diffracted by the hologram element; and an incidence preventing area placed between the hologram element and the light receiving elements for, in the case where the light beam is focused on the recording surface on a side close to the objective lens out of recording surfaces of multilayer of the optical information recording medium, substantially preventing reflected light from the recording surface on a side remote from the objective lens from entering the light receiving elements.
摘要:
The optical pickup device according to the present invention includes: a light source which emits light at first, second and third wavelengths; an optical path combining unit which combines vectors of the light at the first, second and third wavelengths which is emitted by the light source, and matches optical axes of the light at the first wavelength and the light at the third wavelength; a light condensing unit which condenses the light from the optical path combining unit onto the optical information storage medium; a diffraction element which diffracts light at the first, second and third wavelength which is reflected from the optical information storage medium, in a first direction and a second direction respectively; a first photo detector which receives light at the first, second and third wavelength that is diffracted in the first direction by the diffraction element; a second photo detector which receives light at the first and third wavelength that is diffracted in the second direction by the diffraction element; and a third photo detector which receives light at the second wavelength that is diffracted in the second direction by the diffraction element.
摘要:
An optical path coupling member aligns an optical axis directed to a light condensing member of the first wavelength light having a shortest wavelength with that of the third wavelength light having a longest wavelength. A diffraction element condenses +2nd order diffracted light of the first wavelength light and +1st order diffracted light of the second wavelength light and third wavelength light into a first photodetector, the −2nd order diffracted light of the first wavelength light and −1st order diffracted light of the third wavelength light into a second photodetector, and −1st order diffracted light of the remaining second wavelength light into a photodetector, using ±2nd order diffracted light of the first wavelength light and ±1st order diffracted light of the second wavelength light and third wavelength light as signal light from an optical information recording medium. Consequently, the overall size of the optical pickup apparatus is reduced.