Panasonic Corporation

Panasonic Intellectual Property Management Co., Ltd.

Jun-ichi Asada

Kazuo Momoo

Yuichi Takahashi

Yohichi Saitoh

Seiji Nishiwaki

Hideki Hayashi

Hiroaki Matsumiya

Yusuke Kanda

Kenji Otani

An optical pickup includes a light source; a diffraction elementfor generating a write main beam and a read sub-beam via diffraction; an objective lens; a wavelength plate; a polarization hologram elementhaving 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 0order light beam and &#xb1;1order light beams; an actuator; and a photodetectorconfigured to detect a light beam reflected from the optical storage mediumand diffracted by the polarization hologram element. The photodetectorgenerates an RF signal from a detection result concerning a 0order light beam derived from the main beam, generates a focus error signal and a tracking error signal from a detection result concerning one of &#xb1;1order light beams derived from the main beam, and generates a signal indicating that data has been recorded normally from a detection result concerning a 0order light beam derived from the sub-beam.

Optical pickup and optical recording and reproducing device

An optical recording and playback apparatus includes: a light source configured to emit a light beam; a tracking mirror configured to change a direction of the light beam; a collimator configured to form the light beam into a parallel light beam; an objective lens configured to collect the parallel light beam to the optical tape; a lens actuator configured to adjust a position of the objective lens in a focus direction of the optical tape and a position of the objective lens in a tracking direction of the optical tape; a polarization hologram plate configured to separate a reflected light beam of the light beam; a photodetector receiving elements configured to receive the plurality of light fluxes; and a control circuit configured to control the lens actuator and the tracking mirror. The tracking mirror is disposed near the light source, and movable in the tracking direction.

Optical recording and playback apparatus

In one embodiment of the present invention, an optical pickup for writing and reading data on an optical storage medium comprises a diffractive element for diffracting a light beam to split it into multiple light beams. The diffracted light beams includes a zero-order diffracted light beam for writing data on a track of the land or the groove of the optical storage medium and non-zero-order diffracted light beams for reading the data from the track. The diffractive element has first and second diffraction gratings that have mutually different grating vector directions and pitches. The first diffraction grating forms light beam spots on the same track by the non-zero-order and zero-order diffracted light beams. The second diffraction grating forms a light beam spot to extend to both sides of said track, or forms a light beam spot on one side of said track, by the non-zero-order diffracted light beams.

Optical pickup and optical read/write drive

In one embodiment, an optical pickup includes an optical system which forms multiple light beams based on the light emitted from a light source and which converges a write beam and a read beam, thereby forming a main spot and a sub-spot, respectively, on an optical storage medium. This optical system converges the write and read beams onto the optical storage medium so that the main spot moves through the same region on the optical storage medium ahead of the sub-spot. The optical pickup further includes a detector for sensing the write and read beams reflected from the storage medium. The detector includes a first photodiodethat receives the reflected light from the main spotR on the storage medium and a second photodiodethat receives a portion of the reflected light from the sub-spotR.

Optical pickup and optical read/write apparatus

When performing recording/reproduction of information for a given recording layer of an optical disc having three recording layers, influences of reflected light from other recording layers are reduced or removed, thus making it possible to obtain a more stable RF signal or focus error signal. An optical pickup device includes a light source, a collimator lens, an objective lens, a photodetector, and a light shielding member. Among the recording layers of the optical disc, a first layer and a second layer adjoining each other are disposed in the order of the first layer and second layer from near the objective lens. The light shielding member is disposed at a position satisfying the condition d&#x3e;dto block a part of reflected light from the second layer when light is converged on the first layer, where d is an optical path length from the photodetector to the light shielding member; and dis a distance from the photodetector to a position at which reflected light from the second layer becomes focused between the collimator lens and the photodetector.

Optical pickup device and optical disc device

An optical pickup includes: a light source; a first diffractive element which diffracts light polarized in a particular direction; an objective lens; a lens actuator which shifts the objective lens so that the magnitude of shift from its initial position in a tracking direction has an upper limit of 0.3 mm to 0.6 mm; a wave plate; a second diffractive element which has two diffraction regions configured to diffract light polarized in a direction that intersects with the particular direction at right angles and which splits the write beam reflected from the optical storage medium through each diffraction region into a transmitted light beam and at least one diffracted light beam; and a photodetector which detects the transmitted light beam, the diffracted light beams that have left the two diffraction regions, and the read beam reflected from the optical storage medium.

An optical pickup includes a wave plate on an optical path to be followed by every light beam emitted from three light sources (with wavelengths &#x3bb;, &#x3bb;and &#x3bb;, respectively) both on their way toward an optical disc and back from the disc toward a photodetector. The wave plate has two layers with different retardations and different optic axis directions. The sum of the retardations of the first and second layers is defined to be approximately,andto the light beams with the wavelengths &#x3bb;, &#x3bb;and &#x3bb;.

Wave plate, optical pickup and optical disc apparatus

There is provided, in an optical disk apparatus which is capable of recording data to or reading data from a plurality of types of optical disks, a wavelength plate and an optical pickup which can reduce deterioration in signal quality even in the presence of a large birefringence of the substrate of an optical disk. A wavelength plateaccording to the present invention is a wavelength plate to be placed in an optical path through which rays of a plurality of wavelengths travel back and forth, the plurality of wavelengths including a ray having a wavelength &#x3bb;. The wavelength plate includes a two-dimensional array of a plurality of birefringent regions, the birefringent regions including first regions Dand second regions Dhaving different optic axis directions from each other. The relationship 240&#xb0;&#x2266;&#x394;&#x2266;300&#xb0; is true, where &#x394;is a retardation of the wavelength platefor the ray of the wavelength &#x3bb;.

Wavelength plate, optical element, and optical pickup

It is intended to provide an optical disk apparatus which detects a light amount greater than zero even when used in conjunction with an optical disk substrate having a large birefringence, so that it is possible to properly read a signal without errors and properly perform optical disk controls. The optical disk apparatus includes: a light source for emitting light; an objective lens for converging the light onto a signal surface of an optical disk; a polarized beam diffraction element for diffracting the light reflected from the optical disk; a photodetector for detecting the light diffracted from the polarized beam diffraction element; and a wavelength plate disposed between the optical disk and the polarized beam diffraction element. The wavelength plate has a two-dimensional array of a plurality of birefringent regions including first and second regions, the first and second regions differing in birefringent phase difference and/or optic axes from each other, and the plurality of birefringent regions including the first and second regions cause the light to have different polarization states.

Growing community of inventors

Hyogo, Japan

Jun-ichi Asada