US3919562A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Slit detector for optical detector system
Assignee: Zenith Electronics LLC
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Filing: 1974-05-20
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Granted: 1975-11-11
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Expires: 1994-05-20
Abstract
Abstract An optical system for detecting a time-varying signal spatially recorded upon a disc as a light diffraction grating in the form of a spiral track. The disc is driven, relative to a reading spot to develop a time-varying diffraction pattern comprising at least a zero order, +1 order and a -1 order. An aperture, having a dimension in the direction of the track which is less than onehalf the distance across which the zero order is distributed, is positioned in the far field of the diffraction pattern near the boundary of the zero order. A photodetector positioned adjacent the aperture derives an electrical signal representative of the signal spatially recorded on the disc.
Inventors
- 👤 Robert L Whitman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 06:40
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/135; G11B7/1381; G11B7/004; G11B7/005
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
253 words
An optical system for detecting a time-varying signal spatially recorded upon a storage medium to form a light diffraction grating in the shape of an elongated track, said optical detection system comprising: means for supporting said storage medium; means for producing a beam of light; means for focusing said beam to produce a reading spot for illuminating said track, said reading spot having a dimension in the longitudinal direction of said track which is less than the wavelength of the highest spatial frequency recorded upon said stoRage medium; drive means for displacing said medium, relative to said spot, at a predetermined velocity to effect a scan of said track by said reading spot to develop a time-varying diffraction pattern of said spot, said pattern comprising at least a zero order, a +1 order and a -1 order with each of said orders having a distribution parallel to the longitudinal direction of said track, an aperture positioned in the far field of said diffraction pattern near the boundary of said zero order for transmitting at least a portion of said zero order diffraction pattern, said aperture comprising an opening having a dimension parallelling the longitudinal direction of said track which is less than one-half the distance across which said zero order is distributed; and light responsive means positioned adjacent said aperture for deriving, in response to illumination thereof by that portion of said time varying pattern transmitted by said aperture, an electrical signal representative of said time varying signal spatially recorded upon said medium.
Claim 2
Dependent Claim
253 words
An optical system for detecting a time-varying signal spatially recorded upon a storage medium to form a light diffraction grating in the shape of an elongated track, said optical detection system comprising: means for supporting said storage medium; means for producing a beam of light; means for focusing said beam to produce a reading spot for illuminating said track, said reading spot having a dimension in the longitudinal direction of said track which is less than the wavelength of the highest spatial frequency recorded upon said stoRage medium; drive means for displacing said medium, relative to said spot, at a predetermined velocity to effect a scan of said track by said reading spot to develop a time-varying diffraction pattern of said spot, said pattern comprising at least a zero order, a +1 order and a -1 order with each of said orders having a distribution parallel to the longitudinal direction of said track, an aperture positioned in the far field of said diffraction pattern near the boundary of said zero order for transmitting at least a portion of said zero order diffraction pattern, said aperture comprising an opening having a dimension parallelling the longitudinal direction of said track which is less than one-half the distance across which said zero order is distributed; and light responsive means positioned adjacent said aperture for deriving, in response to illumination thereof by that portion of said time varying pattern transmitted by said aperture, an electrical signal representative of said time varying signal spatially recorded upon said medium.
Claim 3
Dependent Claim
34 words
An optical system as set forth in claim 1 in which said aperture is disposed in that region of the far field in which said zero order and one of said first orders overlap.
Claim 4
Dependent Claim
23 words
An optical system as set forth in claim 1 in which said aperture comprises an elongated slit disposed substantially perpendicular to said track.
Claim 5
Dependent Claim
40 words
An optical system as set forth in claim 1 in which said aperture comprises an opaque member having a rectangular opening and in which said opening is oriented so that its shorter dimension is disposed substantially parallel to said track.
Claim 6
Dependent Claim
57 words
An optical system as set forth in claim 1 in which said aperture comprises a trapezoidal opening in which the distance between the parallel sides of said opening is greater than the distance between the non-parallel sides and, in which said trapezoidal opening is oriented so that its parallel sides are disposed substantially parallel to said track.
Claim 7
Dependent Claim
49 words
An optical system as set forth in claim 1 in which said aperture comprises a triangular opening in which the altitude of the triangle is greater than its base and in which said triangular opening is oriented so that its altitude dimension is disposed substantially perpendicular to said track.
References Cited (Backward Citations)
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US3716286A
Cited
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Cited
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-11-10 | 1979-05-12 | 1979-11-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-10 | 1983-05-12 | 1983-11-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-10 | 1987-05-12 | 1987-11-11 | $7700.00 | Window Closed / Lapsed |