EP0258890A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Optical pickup apparatus
Assignee: Fujifilm Holdings Corp
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Filing: 1987-09-02
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Granted: —
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Expires: 2007-09-02
Abstract
Abstract An optical pickup apparatus comprises an optical waveguide (22) disposed to receive a light beam reflected by an optical recording medium (13), first and second focusing grating couplers (31,32) disposed side by side on the optical waveguide for coupling the reflected light beam into the optical waveguide and converging the optical wave guided through the optical waveguide to positions spaced from each other, and first and second photodetectors (24,25) secured to the optical waveguide for respectively detecting the optical waves converged by the first and second focusing grating couplers (31,32) so that reading out of recorded information, detection of tracking error and detection of focusing error can be effected. Or, the optical pickup apparatus comprises a grating lens disposed to receive and split the reflected light beam from an optical path of the light beam advancing toward the optical recording medium and to converge the reflected light beam, and a photodetector for detecting the reflected light beam passing through the grating lens so that reading out of recorded information, detection of a tracking error and detection of a focusing error can be effected.
Inventors
- 👤 Hiroshi Sunagawa
- 👤 Hiroshi Nishihara
- 👤 Toshiaki Suhara
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 12:24
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/135; G11B7/1381; G11B7/08; G11B7/09; G11B7/0901; G11B7/0908; G11B7/0916; G11B7/123; G11B7/124; G11B7/1353
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
248 words
An optical pickup apparatus comprising: i) a light source for emitting a light beam onto a surface of an optical recording medium, ii) an objective lens for converging said light beam onto the reflection surface of said optical recording medium, iii) an optical waveguide disposed in such a direction that one surface thereof receives the light beam reflected by said optical recording medium, iv) a first focusing grating coupler and a second focusing grating coupler disposed side by side at an incidence position of said reflected light beam adjacent the surface of said optical waveguide so that an axis passing through approximately the center of said reflected light beam extending on said surface of said optical waveguide approximately normal to a tracking direction intervenes between said first focusing grating coupler and said second focusing grating coupler, said first focusing grating coupler and said second focusing grating coupler respectively making said reflected light beam enter said optical waveguide and respectively converging the optical wave, which is thus guided through said optical waveguide, to positions spaced from each other with said axis intervening therebetween, and v) a first-set photodetector and a second-set photodetector secured to the surface or an edge face of said optical waveguide for respectively detecting the optical wave converged by said first focusing grating coupler and the optical wave converged by said second focusing grating coupler so that reading out of recorded information, detection of a tracking error and detection of a focusing error can be effected.
Claim 2
Dependent Claim
248 words
An optical pickup apparatus comprising: i) a light source for emitting a light beam onto a surface of an optical recording medium, ii) an objective lens for converging said light beam onto the reflection surface of said optical recording medium, iii) an optical waveguide disposed in such a direction that one surface thereof receives the light beam reflected by said optical recording medium, iv) a first focusing grating coupler and a second focusing grating coupler disposed side by side at an incidence position of said reflected light beam adjacent the surface of said optical waveguide so that an axis passing through approximately the center of said reflected light beam extending on said surface of said optical waveguide approximately normal to a tracking direction intervenes between said first focusing grating coupler and said second focusing grating coupler, said first focusing grating coupler and said second focusing grating coupler respectively making said reflected light beam enter said optical waveguide and respectively converging the optical wave, which is thus guided through said optical waveguide, to positions spaced from each other with said axis intervening therebetween, and v) a first-set photodetector and a second-set photodetector secured to the surface or an edge face of said optical waveguide for respectively detecting the optical wave converged by said first focusing grating coupler and the optical wave converged by said second focusing grating coupler so that reading out of recorded information, detection of a tracking error and detection of a focusing error can be effected.
Claim 3
Dependent Claim
62 words
An apparatus as defined in Claim 1 wherein said first-set photodetector and said second-set photodetector are respectively composed of two photodetectors divided from each other by a gap extending approximately in parallel with said axis so that detection of a tracking error can be effected by a push-pull technique and detection of a focusing error can be effected by a Foucault technique.
Claim 4
Dependent Claim
34 words
An apparatus as defined in Claim 1 wherein a support of said optical waveguide is formed of a transparent member, and said optical waveguide is disposed between said light source and said objective lens.
Claim 5
Dependent Claim
34 words
An apparatus as defined in Claim 2 wherein a support of said optical waveguide is formed of a transparent member, and said optical waveguide is disposed between said light source and said objective lens.
Claim 6
Dependent Claim
57 words
An apparatus as defined in Claim 1 wherein a buffer layer is disposed between said optical waveguide and a support of said optical waveguide, and said optical waveguide id disposed so that said light beam emitted by said light source is reflected by a boundary between said buffer layer and said support toward said optical recording medium.
Claim 7
Dependent Claim
57 words
An apparatus as defined in Claim 2 wherein a buffer layer is disposed between said optical waveguide and a support of said optical waveguide, and said optical waveguide is disposed so that said light beam emitted by said light source is reflected by a boundary between said buffer layer and said support toward said optical recording medium.
Claim 8
Dependent Claim
37 words
An apparatus as defined in Claim 1 wherein said optical waveguide and said objective lens are disposed independently of each other, and said objective lens alone is moved for the purposes of tracking control and focusing control.
Claim 9
Dependent Claim
37 words
An apparatus as defined in Claim 2 wherein said optical waveguide and said objective lens are disposed independently of each other, and said objective lens alone is moved for the purpose of tracking control and focusing control.
Claim 10
Dependent Claim
37 words
An apparatus as defined in Claim 3 wherein said optical waveguide and said objective lens are disposed independently of each other, and said objective lens alone is moved for the purposes of tracking control and focusing control.
Claim 11
Independent Claim
37 words
An apparatus as defined in Clam 4 wherein said optical waveguide and said objective lens are disposed independently of each other, and said objective lens alone is moved for the purpose of tracking control and focusing control.
Claim 12
Independent Claim
37 words
An apparatus as defined in Clam 4 wherein said optical waveguide and said objective lens are disposed independently of each other, and said objective lens alone is moved for the purpose of tracking control and focusing control.
Claim 13
Dependent Claim
37 words
An apparatus as defined in Claim 5 wherein said optical waveguide and said objective lens are disposed independently of each other, and said objective lens alone is moved for the purpose of tracking control and focusing control.
Claim 14
Dependent Claim
37 words
An apparatus as defined in Claim 6 wherein said optical waveguide and said objective lens are disposed independently of each other, and said objective lens alone is moved for the purposes of tracking control and focusing control.
Claim 15
Dependent Claim
35 words
An apparatus as defined in Claim 1 wherein said optical waveguide is disposed integrally with said objective lens and is moved together with said objective lens for the purposes of tracking control and focusing control.
Claim 16
Dependent Claim
35 words
An apparatus as defined in Claim 2 wherein said optical waveguide is disposed integrally with said objective lens and is moved together with said objective lens for the purposes of tracking control and focusing control.
Claim 17
Dependent Claim
35 words
An apparatus as defined in Claim 3 wherein said optical waveguide is disposed integrally with said objective lens and is moved together with said objective lens for the purposes of tracking control and focusing control.
Claim 18
Dependent Claim
35 words
An apparatus as defined in Claim 4 wherein said optical waveguide is disposed integrally with said objective lens and is moved together with said objective lens for the purposes of tracking control and focusing control.
Claim 19
Dependent Claim
35 words
An apparatus as defined in Claim 5 wherein said optical waveguide is disposed integrally with said objective lens and is moved together with said objective lens for the purposes of tracking control and focusing control.
Claim 20
Dependent Claim
35 words
An apparatus as defined in Claim 6 wherein said optical waveguide is disposed integrally with said objective lens and is moved together with said objective lens for the purposes of tracking control and focusing control.
Claim 21
Independent Claim
77 words
An apparatus as defined in any of Claims 1 to 18 wherein said light beam is a laser beam for emitting a linearly polarized laser beam, a quarter-wave plate is disposed in an optical path of the reflected laser beam between said objective lens and said focusing grating couplers, and said focusing grating couplers are formed so that only the reflected laser beam polarized linearly by passage through said quarter-wave plate is coupled into said optical waveguide.
Claim 22
Dependent Claim
127 words
An optical pickup apparatus comprising: i) a light source for emitting a light beam onto a surface of an optical recording medium, ii) an objective lens for converging said light beam onto the reflection surface of said optical recording medium, iii) a grating lens disposed in such a direction that one surface thereof receives the light beam reflected by said optical recording medium, thereby to split said reflected light beam from an optical path of said light beam advancing toward said optical recording medium and to converge said reflected light beam, and iv) a photodetector for detecting said reflected light beam passing through said grating lens so that reading out of recorded information, detection of a tracking error and detection of a focusing error can be effected.
Claim 23
Dependent Claim
127 words
An optical pickup apparatus comprising: i) a light source for emitting a light beam onto a surface of an optical recording medium, ii) an objective lens for converging said light beam onto the reflection surface of said optical recording medium, iii) a grating lens disposed in such a direction that one surface thereof receives the light beam reflected by said optical recording medium, thereby to split said reflected light beam from an optical path of said light beam advancing toward said optical recording medium and to converge said reflected light beam, and iv) a photodetector for detecting said reflected light beam passing through said grating lens so that reading out of recorded information, detection of a tracking error and detection of a focusing error can be effected.
Claim 24
Dependent Claim
162 words
An apparatus as defined in Claim 20 wherein said grating lens comprises a first grating lens and a second grating lens disposed side by side so that an axis passing through nearly the center of said reflected light beam and extending approximately normal to a tracking direction intervenes between said first grating lens and said second grating lens, said first grating lens and said second grating lens converging said reflected light beam to positions spaced from each other, and said photodetector comprises a first-set photodetector composed of two photodetectors divided from each other and a second-set photodetector composed of two photodetectors divided from each other, said first-set photodetector and said second-set photodetector respectively detecting the reflected light beam converged by said first grating lens and the reflected light beam converged by said second grating lens so that detection of a tracking error can be effected by a push-pull technique and detection of a focusing error can be effected by a Foucault technique.
Claim 25
Dependent Claim
56 words
An apparatus as defined in Claim 20 wherein said grating lens is constituted by an astigmatism lens, and said photodetector comprises four photodetectors divided from each other and disposed so that detection of a tracking error can be effected by a heterodyning technique and detection of a focusing error can be effected by an astigmatism technique.
Claim 26
Dependent Claim
21 words
An apparatus as defined in Claim 20 wherein said grating lens is disposed between said light source and said objective lens.
Claim 27
Dependent Claim
21 words
An apparatus as defined in Claim 21 wherein said grating lens is disposed between said light source and said objective lens.
Claim 28
Dependent Claim
21 words
An apparatus as defined in Claim 22 wherein said grating lens is disposed between said light source and said objective lens.
Claim 29
Dependent Claim
28 words
An apparatus as defined in Claim 20 wherein said grating lens is disposed to reflect said light beam emitted by said light source toward said optical recording medium.
Claim 30
Dependent Claim
28 words
An apparatus as defined in Claim 21 wherein said grating lens is disposed to reflect said light beam emitted by said light source toward said optical recording medium.
Claim 31
Dependent Claim
28 words
An apparatus as defined in Claim 22 wherein said grating lens is disposed to reflect said light beam emitted by said light source toward said optical recording medium.
Claim 32
Independent Claim
41 words
An apparatus as defined in any of Claims 20 to 28 wherein said grating lens and said objective lens are disposed independently of each other, and said objective lens alone is moved for the purposes of tracking control and focusing control.
Claim 33
Independent Claim
39 words
An apparatus as defined in any of Claims 20 to 28 wherein said grating lens is disposed integrally with said objective lens and is moved together with said objective lens for the purposes of tracking control and focusing control.
References Cited (Backward Citations)
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