US5036504A
Expired / Lapsed
US
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Optical head using a reflection grating
Assignee: NEC Corp
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Filing: 1988-11-30
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Granted: 1991-07-30
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Expires: 2008-11-30
Abstract
Abstract An optical head includes a reflection type grating lens for dividing specified polarized lights into a reflected light and a diffracted light, a device for detecting a RF signal from the reflected light of the grating lens, and a device for detecting focusing and tracking error signals from the diffracted light of the grating lens. The grating lens consists of a plurality of domains having different optical properties respectively, so that the reflected and diffracted lights are obtained. The optical head further includes a total reflection prism to compensate a phase difference between polarized lights orthogonal to a grating groove of the grating lens and parallel thereto, and a polarizing prism for dividing the reflected light into two polarized lights orthogonal to each other in polarization thereof. Thus, a simple, miniaturized, and inexpensive optical head is obtained.
Inventors
- 👤 Yuzo Ono
- 👤 Akitomo Ohba
- 👤 Yasuo Kimura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 05:38
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/135; G11B7/1381; G11B7/08; G11B7/09; G11B7/0901; G11B7/0903; G11B7/0908; G11B7/0912; G11B7/0916; G11B7/1353; G11B7/1372; G11B7/1378
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
122 words
An optical head comprising; means for radiating a light beam; a beam splitter for transmitting said light beam therethrough and reflecting light beam reflected from a disk; a focusing lens for focusing said light beam on said disk and transmitting light beam reflected from said disk therethrough; a reflection type grating lens including a plurality of regions having different optical properties for diffracting mainly specified polarized light included in said light beam from said beam splitter; means for detecting a signal stored in said disk in accordance with said reflected light of said reflection type grating lens; and means for detecting a focusing error signal and a tracking error signal in accordance with said diffracted light of said reflection type grating lens.
Claim 2
Dependent Claim
122 words
An optical head comprising; means for radiating a light beam; a beam splitter for transmitting said light beam therethrough and reflecting light beam reflected from a disk; a focusing lens for focusing said light beam on said disk and transmitting light beam reflected from said disk therethrough; a reflection type grating lens including a plurality of regions having different optical properties for diffracting mainly specified polarized light included in said light beam from said beam splitter; means for detecting a signal stored in said disk in accordance with said reflected light of said reflection type grating lens; and means for detecting a focusing error signal and a tracking error signal in accordance with said diffracted light of said reflection type grating lens.
Claim 3
Dependent Claim
36 words
An optical head according to claim 1 further comprising, a polarizing prism for dividing the zero-order diffraction light supplied from said reflection type grating lens into two polarized lights orthogonal to each other in polarizations thereof.
Claim 4
Dependent Claim
57 words
An optical head according to claim 2 further comprising, a total reflection prism for compensating a phase difference between polarized lights orthogonal to a grating groove of said reflection type grating lens and parallel thereto, said total reflection prism being provided at a specific position on a light path between said focusing lens and said polarizing prism.
Claim 5
Dependent Claim
18 words
An optical head according to claim 1, wherein said means for detecting a signal comprises a two-divided photodetector.
Claim 6
Dependent Claim
25 words
An optical head according to claim 1, wherein said means for detecting a focusing error signal and a tracking error signal comprises a six-divided photodetector.
Claim 7
Dependent Claim
151 words
An optical head comprising: means for radiating a light beam; a beam splitter for transmitting said light beam therethrough and reflecting light beam reflected from a disk; a focusing lens for focusing said light beam on said disk and transmitting light beam reflected from said disk therethrough; a reflection type grating lens including a plurality of different optical properties for dividing specified polarized lights included in said light beam from said beam splitter into reflected and diffracted lights; a polarizing prism for dividing the zero-order diffraction light supplied from said reflection type grating lens into two polarized lights orthogonal to each other in polarizations thereof; means for detecting a signal stored in said disk in accordance with said reflected light of said reflection type grating lens; and means for detecting a focusing error signal and a tracking error signal in accordance with said diffracted light of said reflection type grating lens.
Claim 8
Dependent Claim
151 words
An optical head comprising: means for radiating a light beam; a beam splitter for transmitting said light beam therethrough and reflecting light beam reflected from a disk; a focusing lens for focusing said light beam on said disk and transmitting light beam reflected from said disk therethrough; a reflection type grating lens including a plurality of different optical properties for dividing specified polarized lights included in said light beam from said beam splitter into reflected and diffracted lights; a polarizing prism for dividing the zero-order diffraction light supplied from said reflection type grating lens into two polarized lights orthogonal to each other in polarizations thereof; means for detecting a signal stored in said disk in accordance with said reflected light of said reflection type grating lens; and means for detecting a focusing error signal and a tracking error signal in accordance with said diffracted light of said reflection type grating lens.
Claim 9
Dependent Claim
199 words
An optical head comprising: means for radiating a light beam; a beam splitter for transmitting said light beam therethrough and reflecting light beam reflected from a disk; a focusing lens for focusing said light beam on said disk and transmitting light beam reflected from said disk therethrough; a reflection type grating lens including a plurality of different optical properties for dividing specified polarized lights included in said light beam from said beam splitter into reflected and diffracted lights; a polarizing prism for dividing the zero-order diffraction light supplied from said reflection type grating lens into two polarized lights orthogonal to each other in polarizations thereof; a total reflection prism for compensating a phase difference between polarized lights orthogonal to a grating groove of said reflection type grating lens and parallel thereto, said total reflection prism being provided at a specific position on a light path between said focusing lens and said polarizing prism; means for detecting a signal stored in said disk in accordance with said reflected light of said reflection type grating lens; and means for detecting a focusing error signal and a tracking error signal in accordance with said diffracted light of said reflection type grating lens.
Claim 10
Dependent Claim
199 words
An optical head comprising: means for radiating a light beam; a beam splitter for transmitting said light beam therethrough and reflecting light beam reflected from a disk; a focusing lens for focusing said light beam on said disk and transmitting light beam reflected from said disk therethrough; a reflection type grating lens including a plurality of different optical properties for dividing specified polarized lights included in said light beam from said beam splitter into reflected and diffracted lights; a polarizing prism for dividing the zero-order diffraction light supplied from said reflection type grating lens into two polarized lights orthogonal to each other in polarizations thereof; a total reflection prism for compensating a phase difference between polarized lights orthogonal to a grating groove of said reflection type grating lens and parallel thereto, said total reflection prism being provided at a specific position on a light path between said focusing lens and said polarizing prism; means for detecting a signal stored in said disk in accordance with said reflected light of said reflection type grating lens; and means for detecting a focusing error signal and a tracking error signal in accordance with said diffracted light of said reflection type grating lens.
References Cited (Backward Citations)
US4733065A
Cited
US4665310A
Cited
US4945529A
Cited
US4753513A
Cited
US4731772A
Cited
US4885734A
Cited
US4768183A
Cited
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