US 9,361,927 B2Granted

Optical pickup and optical recording and reproducing device

AssigneePanasonic Intellectual Property Management Co., Ltd.

InventorsJun-ichi Asada, Yuichi Takahashi, Hiroaki Matsumiya, Kazuo Momoo

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Abstract

An optical pickup includes a light source 1; a diffraction element 2 for generating a write main beam and a read sub-beam via diffraction; an objective lens 5; a wavelength plate 9; a polarization hologram element 7 having a plurality of diffraction regions with different diffraction characteristics, designed so that each diffraction region separates a light beam reflected from the optical storage medium and transmitted through the wavelength plate into a 0th order light beam and ±1st order light beams; an actuator 11; and a photodetector 10 configured to detect a light beam reflected from the optical storage medium 6 and diffracted by the polarization hologram element 7. The photodetector 10 generates an RF signal from a detection result concerning a 0th order light beam derived from the main beam, generates a focus error signal and a tracking error signal from a detection result concerning one of ±1st order light beams derived from the main beam, and generates a signal indicating that data has been recorded normally from a detection result concerning a 0th order light beam derived from the sub-beam.

Claims10

Dependent claims

An optical pickup for, while recording data onto a track of an optical storage medium, reading data that has been recorded on the track, comprising:

a light source for emitting a light beam;
a diffraction element for separating the light beam emitted from the light source into a plurality of light beams including a write main beam and a read sub-beam;
an objective lens configured to converge the main beam and the sub-beam onto a same track on the optical storage medium;
a wavelength plate disposed on an optical path from the diffraction element to the optical storage medium, the wavelength plate being designed so that a polarization direction of light which is incident from the diffraction element onto the wavelength plate is orthogonal to a polarization direction of light reflected from the optical storage medium and transmitted through the wavelength plate;
a polarization hologram element having a plurality of diffraction regions with different diffraction characteristics, designed so that each diffraction region separates a light beam reflected from the optical storage medium and transmitted through the wavelength plate into a 0th order light beam and ±1st order light beams;
an actuator for integrally driving the objective lens and the polarization hologram element for focus control and tracking control;
and
a photodetector configured to detect a light beam reflected from the optical storage medium and diffracted by the polarization hologram element, the photodetector generating an RF signal from a detection result concerning a 0th order light beam derived from the main beam, generating a focus error signal and a tracking error signal from a detection result concerning one of ±1st order light beams derived from the main beam, and generating a signal indicating that data has been recorded normally from a detection result concerning a 0th order light beam derived from the sub-beam,
wherein the plurality of diffraction regions of the polarization hologram element are four regions divided around a center which is a point traveled by a central portion of the main beam, the division being made by a straight line in a same direction as a track of the optical storage medium and a straight line in a perpendicular direction to the track.

6 more elements

An optical pickup for, while recording data onto a track of an optical storage medium, reading data that has been recorded on the track, comprising:

a light source for emitting a light beam;
a diffraction element for separating the light beam emitted from the light source into a plurality of light beams including a write main beam and a read sub-beam;
an objective lens configured to converge the main beam and the sub-beam onto a same track on the optical storage medium;
a wavelength plate disposed on an optical path from the diffraction element to the optical storage medium, the wavelength plate being designed so that a polarization direction of light which is incident from the diffraction element onto the wavelength plate is orthogonal to a polarization direction of light reflected from the optical storage medium and transmitted through the wavelength plate;
a polarization hologram element having a plurality of diffraction regions with different diffraction characteristics, designed so that each diffraction region separates a light beam reflected from the optical storage medium and transmitted through the wavelength plate into a 0th order light beam and ±1st order light beams;
an actuator for integrally driving the objective lens and the polarization hologram element for focus control and tracking control;
and
a photodetector configured to detect a light beam reflected from the optical storage medium and diffracted by the polarization hologram element, the photodetector generating an RF signal from a detection result concerning a 0th order light beam derived from the main beam, generating a focus error signal and a tracking error signal from a detection result concerning one of ±1st order light beams derived from the main beam, and generating a signal indicating that data has been recorded normally from a detection result concerning a 0th order light beam derived from the sub-beam,
wherein the photodetector generates the tracking error signal by a correct far field method and generates the focus error signal by a spot size detection method.

6 more elements

An optical pickup for, while recording data onto a track of an optical storage medium, reading data that has been recorded on the track, comprising:

a light source for emitting a light beam;
a diffraction element for separating the light beam emitted from the light source into a plurality of light beams including a write main beam and a read sub-beam;
an objective lens configured to converge the main beam and the sub-beam onto a same track on the optical storage medium;
a wavelength plate disposed on an optical path from the diffraction element to the optical storage medium, the wavelength plate being designed so that a polarization direction of light which is incident from the diffraction element onto the wavelength plate is orthogonal to a polarization direction of light reflected from the optical storage medium and transmitted through the wavelength plate;
a polarization hologram element having a plurality of diffraction regions with different diffraction characteristics, designed so that each diffraction region separates a light beam reflected from the optical storage medium and transmitted through the wavelength plate into a 0th order light beam and ±1st order light beams;
an actuator for integrally driving the objective lens and the polarization hologram element for focus control and tracking control;
and
a photodetector configured to detect a light beam reflected from the optical storage medium and diffracted by the polarization hologram element, the photodetector generating an RF signal from a detection result concerning a 0th order light beam derived from the main beam, generating a focus error signal and a tracking error signal from a detection result concerning one of ±1st order light beams derived from the main beam, and generating a signal indicating that data has been recorded normally from a detection result concerning a 0th order light beam derived from the sub-beam,
wherein,
the photodetector includes
a first photosensitive element for detecting a 0th order light beam derived from the main beam,
a second photosensitive element for detecting one of the +1st order light beam and the −1st order light beam derived from the main beam, the second photosensitive element having a same number of photosensitive portions as the number of diffraction regions of the polarization hologram element, and
a third photosensitive element for detecting a 0th order light beam derived from the sub-beam;
and
the first photosensitive element and the photosensitive portions of the second photosensitive element are arranged along a same direction as a direction in which a light spot on the photodetector moves when the objective lens shifts in a direction perpendicular to a track direction of the optical storage medium.

12 more elements

An optical pickup for, while recording data onto a track of an optical storage medium, reading data that has been recorded on the track, comprising:

a light source for emitting a light beam;
a diffraction element for separating the light beam emitted from the light source into a plurality of light beams including a write main beam and a read sub-beam;
an objective lens configured to converge the main beam and the sub-beam onto a same track on the optical storage medium;
a wavelength plate disposed on an optical path from the diffraction element to the optical storage medium, the wavelength plate being designed so that a polarization direction of light which is incident from the diffraction element onto the wavelength plate is orthogonal to a polarization direction of light reflected from the optical storage medium and transmitted through the wavelength plate;
a polarization hologram element having a plurality of diffraction regions with different diffraction characteristics, designed so that each diffraction region separates a light beam reflected from the optical storage medium and transmitted through the wavelength plate into a 0th order light beam and ±1st order light beams;
an actuator for integrally driving the objective lens and the polarization hologram element for focus control and tracking control;
and
a photodetector configured to detect a light beam reflected from the optical storage medium and diffracted by the polarization hologram element, the photodetector generating an RF signal from a detection result concerning a 0th order light beam derived from the main beam, generating a focus error signal and a tracking error signal from a detection result concerning one of ±1st order light beams derived from the main beam, and generating a signal indicating that data has been recorded normally from a detection result concerning a 0th order light beam derived from the sub-beam,
further comprising a collimating lens and a detection lens between the polarization hologram element and the photodetector, wherein
100 μm<f2/f1×d<500 μm
is satisfied, where f1 is a focal length of the objective lens;
f2 is a combined focal length of the collimating lens and the detection lens;
and d is an interval between a light spot by the main beam formed on the track of the optical storage medium and a light spot by the sub-beam.

10 more elements

Dependencies are inferred from the claim text.

Facts

Application: 14/650,139Filed 27 Jun 2013
Priority: JP 2012-27104512 Dec 2012
Published: US 2015/0318010 A15 Nov 2015
Granted: 7 Jun 2016
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

G11B 7/00458
Recording: verification, i.e. checking data during or after recording
G11B 7/0903
For track following only: multi-beam tracking systems
G11B 7/0912
For focusing only: by push-pull method
G11B 7/1353
Means for guiding the beam from the source to the record carrier or from the record carrier to the detector: diffractive elements, e.g. holograms…