US 2003/0076592 A1Published application

Optical device

AssigneeVictor Company of Japan, Ltd.

InventorMinoru Ohyama

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Abstract

There is disclosed an optical device in which a first light source for outputting a first wavelength light is apart from a second light source for outputting a second wavelength light by a predetermined distance. An information recording medium is irradiated with the first and second wavelength lights transmitted through a holographic optical element having first and second diffraction areas. The first and second diffraction areas are provided with grating arrangements in which grating axis directions are parallel to each other and grating pitches are different from each other. The first and second wavelength lights reflected by the information recording medium are transmitted through the holographic optical element and diffracted by the first and second diffraction areas. The first and second wavelength diffracted lights by the first diffraction area are converged to much the same first position on a light receiving element substrate, and the first and second wavelength diffracted lights by the second diffraction area are converged to substantially the same second position on the light receiving element substrate. First and second light receiving elements are disposed in the first and second positions, respectively.

Claims14

Dependent claims

An optical device for reading information from an information recording medium, comprising:

a first light source for outputting a light of a first wavelength;
a second light source for outputting a light of a second wavelength;
a holographic optical element having a first diffraction area and a second diffraction area for diffracting the lights of said first and second wavelengths;
and
a light receiving element substrate provided with a first light receiving element and a second light receiving element for receiving a diffracted light from said holographic optical element, wherein
said first diffraction area and the second diffraction area have grating arrangements whose grating axis directions are parallel to each other and whose grating pitches are different from each other, and light emitting points of said first and second light sources are apart from each other by a predetermined distance in a direction crossing at right angles to said grating axis,
the grating pitches of said first diffraction area and the second diffraction area are determined in such a manner that:
when a distance (L11;
L12) between an incident position of the diffracted light of said first wavelength to the surface of said light receiving element substrate by the first diffraction area or the second diffraction area, and an optical axis determined by a 0th order transmitted light of the first wavelength is a first distance, and a distance (L21;
L22) between an incident position of the diffracted light of said second wavelength to said light receiving element substrate surface by the same diffraction area, and the optical axis determined by the 0th order transmitted light of the second wavelength is a second distance, a difference (|L11−L21|;
|L12−L22|) between said first distance and the second distance becomes equal to an interval between the light emitting points of said first and second light sources;
and
an interval (|L11−L12|;
|L21−L22|) between the incident position of the diffracted light of said first or second wavelength to said light receiving element substrate surface by said first diffraction area, and the incident position of the diffracted light of the same wavelength to said light receiving element substrate surface by the second diffraction area becomes equal to the interval between said light emitting points,
the diffracted lights of the first wavelength and the second wavelength by said first diffraction area are converged to much the same first position on said light receiving element substrate, and the diffracted lights of the first wavelength and the second wavelength by said second diffraction area are converged to about the same second position on said light receiving element substrate, and
the first and second light receiving elements are disposed in said first and second positions, respectively.

13 more elements

An optical device for reading information from an information recording medium, comprising:

a first light source for outputting a light of a first wavelength;
a second light source for outputting a light of a second wavelength;
a holographic optical element having a first diffraction area and a second diffraction area for diffracting the lights of said first and second wavelengths;
and
a light receiving element substrate provided with a first light receiving element and a second light receiving element for receiving a diffracted light from said holographic optical element, wherein
in said first diffraction area and the second diffraction area, grating pitches are identical with each other, grating axis directions are different from each other by a predetermined angle of 30° or less, and light emitting points of said first and second light sources are apart from each other by a predetermined distance in a direction crossing at right angles to said grating axis direction,
the grating pitches of said first diffraction area and the second diffraction area are determined in such a manner that:
when a distance between an incident position of the diffracted light of said first wavelength to the surface of said light receiving element substrate by the first diffraction area or the second diffraction area, and an optical axis determined by a 0th order transmitted light of the first wavelength is a first distance, and a distance between an incident position of the diffracted light of said second wavelength to the surface of said light receiving element substrate by the same diffraction area, and the optical axis determined by the 0th order transmitted light of the second wavelength is a second distance, a difference between said first distance and the second distance becomes equal to an interval between the light emitting points of said first and second light sources,
directions of said first diffraction area and the second diffraction area are determined in such a manner that:
the diffracted lights of the first wavelength and the second wavelength by said first diffraction area are converged to much the same first position on said light receiving element substrate;
and
the diffracted lights of the first wavelength and the second wavelength by said second diffraction area are converged to about the same second position apart from said first position by a predetermined distance in a direction crossing at right angles to the apart direction of said light emitting points on said light receiving element substrate, and
the first and second light receiving elements are disposed in said first and second positions, respectively.

10 more elements

An optical device for using a laser light having a predetermined wavelength to read information from an information recording medium, comprising:

a laser light source for generating said laser light;
a light receiving element substrate provided with a plurality of light receiving areas in the same plane;
a 3-beam generating diffraction grating for branching the laser light from said laser light source to three emitted lights;
and
a holographic optical element, divided into at least a first area and a second area in the same plane, for branching a reflected light from said information recording medium and turning the light to said light receiving element substrate,
wherein diffraction axes of said first area and the second area are formed in such a manner that a diffraction axis direction of ±1st order diffracted lights by the first area and the diffraction axis direction of the ±1st order diffracted lights by the second area form predetermined angles in opposite directions with respect to a radial axis crossing at right angles to a track of said information recording medium, and
said holographic optical element first area and second area, and the 3-beam generating diffraction grating are constituted in such a manner that
when one of the ±1st order diffracted lights branched by said 3-beam generating diffraction grating is a first side beam, and the other is a second side beam,
the diffracted light of said first side beam by said first area is overlapped with the diffracted light of said second side beam by said second area on said light receiving element substrate.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/315,067Filed 10 Dec 2002
Priority: JP P11-35806916 Dec 1999
Published: 24 Apr 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

G11B 7/131
Optical detectors therefor: arrangement of detectors in a multiple array
G11B 7/0903
For track following only: multi-beam tracking systems
G11B 7/0912
For focusing only: by push-pull method
G11B 7/123
Heads, e.g. forming of the optical beam spot or modulation of the optical beam: integrated head arrangements, e.g. with source and detectors…

Family

Application09/736,176Division · filed 15 Dec 2000
Application10/315,067Division · filed 10 Dec 2002
US 2002/0008888 A1Published application
US 6,512,608 B2Related patent
US 6,891,675 B2Related patent
US 2003/0076592 A1This patent

From the US filing history. Foreign family members aren’t listed.