US5638353A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical head device
Assignee: NEC Corp
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Filing: 1996-05-23
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Granted: 1997-06-10
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Expires: 2016-05-23
Abstract
Abstract An optical head device which has: a light source for projecting laser light; a beam splitter for reflecting the laser light onto an optical disk; an objective for focusing the reflected light on an information recording surface of the optical disk to form a micro spot thereon; an optical detector for receiving a light component transmitted through the beam splitter of light reflected on the information recording surface and converting the light component into an electrical signal; a variable aperture device for varying a diameter of the micro spot according to an external input, the variable aperture device being provided between the beam splitter and the objective; and a variable rotation angle diffraction grating for varying a rotation angle of a sub-beam for tracking of the laser light according to an external input, the variable rotation angle diffraction grating being provided between the light source and the beam splitter.
Inventors
- 👤 Jun-ichi Takahashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 11:26
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/135; G11B7/1395; G11B7/08; G11B7/09; G11B7/0901; G11B7/0903; G11B7/1353; G11B7/1381; G11B7/139; G11B2007/0003; G11B2007/0006
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
148 words
An optical head device, comprising: a light source for projecting laser light; a beam splitter for reflecting the laser light onto an optical disk; an objective for focusing said reflected light on an information recording surface of said optical disk to form a micro spot thereon; an optical detector for receiving a light component transmitted through said beam splitter of light reflected on said information recording surface and converting said light component into an electrical signal; a variable aperture device for varying a diameter of said micro spot according to an external input, said variable aperture device being provided between said beam splitter and said objective; and a variable rotation angle diffraction grating for varying a rotation angle of a sub-beam for tracking of said laser light according to an external input, said variable rotation angle diffraction grating being provided between said light source and said beam splitter.
Claim 2
Dependent Claim
148 words
An optical head device, comprising: a light source for projecting laser light; a beam splitter for reflecting the laser light onto an optical disk; an objective for focusing said reflected light on an information recording surface of said optical disk to form a micro spot thereon; an optical detector for receiving a light component transmitted through said beam splitter of light reflected on said information recording surface and converting said light component into an electrical signal; a variable aperture device for varying a diameter of said micro spot according to an external input, said variable aperture device being provided between said beam splitter and said objective; and a variable rotation angle diffraction grating for varying a rotation angle of a sub-beam for tracking of said laser light according to an external input, said variable rotation angle diffraction grating being provided between said light source and said beam splitter.
Claim 3
Dependent Claim
24 words
An optical head device, according to claim 1, wherein: said variable aperture device is composed of an electrical acoustooptic member or a magnetooptical member.
Claim 4
Dependent Claim
41 words
An optical head device, according to claim 2, wherein: said variable aperture device is composed of a glass plate or crystal optical member on which said electrical acoustooptic member or magnetooptical member for controlling transmission and interception of light is provided.
Claim 5
Dependent Claim
18 words
An optical head device, according to claim 1, wherein: said variable aperture device is integrated with said objective.
Claim 6
Dependent Claim
26 words
An optical head device, according to claim 1, wherein: said variable rotation angle diffraction grating is composed of an electrical acoustooptic member or a magnetooptical member.
Claim 7
Dependent Claim
41 words
An optical head device, according to claim 5, wherein: said variable rotation angle diffraction grating is composed of a glass plate or crystal optical member on which said electrical acoustooptic member or magnetooptical member for varying said rotation angle is provided.
Claim 8
Dependent Claim
33 words
An optical head device, according to claim 5, wherein: said variable rotation angle diffraction grating comprises two or more diffraction gratings which are previously set to match with a location of said sub-beam.
References Cited (Backward Citations)
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