US5003528A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photorefractive, erasable, compact laser disk
Assignee: United States Department of the Air Force
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Filing: 1988-09-09
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Granted: 1991-03-26
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Expires: 2008-09-09
Abstract
Abstract The invention comprises a data storage device in which ferroelectric photorefractive cells 12 susceptible to polarization for the storage of digital information are positioned on a carrier medium, preferably a disk 10, which supports the cells and allows access to them by optical beams 14, 16 and electric fields 21. A non-contacting data writing means comprising dual electrodes 20, 22 is used to change the polarity of the cells. A non-contacting data reading means comprising lasers 14, 16 and detectors 30, 34 is used to observe photorefractive effects so that the polarity of such cells 12 can be determined. The polarity of the ferroelectric photorefractive cells is coded for the storage of digital information.
Inventors
- 👤 Raymond A. Motes
- 👤 Ronald W. Gallegos
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 20:15
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/002; G11B7/0037
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
74 words
A data storage media comprising: a layer of ferroelectric photorefractive cells, said cells being selectively polarizable by means of electric fields; and a carrier medium for supporting said layer of ferroelectric photorefractive cells, said carrier medium and said layer being optically transparent, and said carrier medium being non-conductive to electric currents so that said electric fields penetrate said carrier medium to interact with said layer of ferroelectric photorefractive cells to selectively polarize said cells.
Claim 2
Dependent Claim
74 words
A data storage media comprising: a layer of ferroelectric photorefractive cells, said cells being selectively polarizable by means of electric fields; and a carrier medium for supporting said layer of ferroelectric photorefractive cells, said carrier medium and said layer being optically transparent, and said carrier medium being non-conductive to electric currents so that said electric fields penetrate said carrier medium to interact with said layer of ferroelectric photorefractive cells to selectively polarize said cells.
Claim 3
Dependent Claim
15 words
The data storage media of claim 1 wherein said ferroelectric photorefractive cells comprise Barium Titanate.
Claim 4
Dependent Claim
19 words
The data storage media of claim 1 wherein said substantially transparent carrier media comprises a compact data storage disk.
Claim 5
Dependent Claim
21 words
The data storage media of claim 1 wherein said substantially transparent carrier media comprises a plastic tape arranged for data recording.
Claim 6
Dependent Claim
46 words
The data storage media of claim 1 wherein said ferroelectric photorefractive cells comprise a material selected from the group consisting of: (a) Barium Titanate; (b) Lithium Niobate; (c) Potassium Niobate; (d) Lithium Tantalate; (e) Lead Zirconate; (f) Potassium Tantalate; (g) Lead Zirconate Titanate; and (h) PLZT.
Claim 7
Dependent Claim
114 words
A data storage device comprising: a data storage media comprising: ferroelectric photorefractive cells susceptible to polarization for the storage of digital information; and a substantially transparent carrier medium, non-conductive to electric currents, for supporting said ferroelectric photorefractive cells and allowing access to said cells by optical beams therethrough and electric fields therethrough; a data writing means utilizing electric fields for changing the polarity of said cells, said data writing means being located externally from said data storage media; and a data reading means utilizing laser light for observing photorefractive effects in said cells determined by the polarity of said ferroelectric photorefractive cells, said data reading means being located externally from said data storage media.
Claim 8
Dependent Claim
114 words
A data storage device comprising: a data storage media comprising: ferroelectric photorefractive cells susceptible to polarization for the storage of digital information; and a substantially transparent carrier medium, non-conductive to electric currents, for supporting said ferroelectric photorefractive cells and allowing access to said cells by optical beams therethrough and electric fields therethrough; a data writing means utilizing electric fields for changing the polarity of said cells, said data writing means being located externally from said data storage media; and a data reading means utilizing laser light for observing photorefractive effects in said cells determined by the polarity of said ferroelectric photorefractive cells, said data reading means being located externally from said data storage media.
Claim 9
Dependent Claim
83 words
The data storage device of claim 6 wherein said data reading means comprises: means for generating two laser beams, the laser beams criss-crossing each other in the ferroelectric photorefractive cell to interact with the polarization therein; means for detecting the optical coupling of the two beams which is determined by the direction of the polarization; and means for producing a high signal or a low signal depending on the direction of polarization affect on the criss-crossing beams entering into said means for detecting.
Claim 10
Dependent Claim
24 words
The data storage device as defined in claim 7 further including means to equalize the outputs of two detectors of said means for detecting.
Claim 11
Dependent Claim
20 words
The data storage device of claim 6 wherein said ferroelectric photorefractive cells are vertically polarized relative to the carrier medium.
Claim 12
Dependent Claim
19 words
The data storage device of claim 6 wherein said substantially transparent carrier medium comprises a compact data storage disk.
Claim 13
Dependent Claim
21 words
The data storage device of claim 6 wherein said substantially transparent carrier medium comprises a plastic tape arranged for data recording.
Claim 14
Dependent Claim
45 words
The data storage device of claim 6 wherein said ferroelectric photorefractive crystals comprise a material selected the group consisting of: (a) Barium Titanate; (b) Lithium Niobate; (c) Potassium Niobate; (d) Lithium Tantalate; (e) Lead Zirconate; (f) Potassium Tantalate; (g) Lead Zirconate Titanate; and (h) PLZT.
Claim 15
Dependent Claim
38 words
The data storage device of claim 6 wherein said data writing means comprises a non-contacting electronic write head for producing an electric field at a ferroelectric photorefractive cell in order to select the polarization state of said cell.
Claim 16
Independent Claim
143 words
A method of storing and retrieving information from a compact optical data storage medium, said data storage medium being a layer of ferroelectric photorefractive crystalline material deposited on a substrate, said material forming cells for the storage of information, said method comprising the steps of: setting the polarity of said ferroelectric photorefractive crystalline cells according to a digital code by means of a data writing means which produces a local electric field that sets cell polarity, said data writing means being external to said data storage medium; and reading the polarity of said ferroelectric photorefractive crystalline cells in order to discern a digital code by means of a data reading means wherein a laser light is used to observe photorefractive effects as determined by the polarity of said ferroelectric photorefractive crystalline cells, said data reading means being external to said data storage medium.
Claim 17
Independent Claim
143 words
A method of storing and retrieving information from a compact optical data storage medium, said data storage medium being a layer of ferroelectric photorefractive crystalline material deposited on a substrate, said material forming cells for the storage of information, said method comprising the steps of: setting the polarity of said ferroelectric photorefractive crystalline cells according to a digital code by means of a data writing means which produces a local electric field that sets cell polarity, said data writing means being external to said data storage medium; and reading the polarity of said ferroelectric photorefractive crystalline cells in order to discern a digital code by means of a data reading means wherein a laser light is used to observe photorefractive effects as determined by the polarity of said ferroelectric photorefractive crystalline cells, said data reading means being external to said data storage medium.
Claim 18
Dependent Claim
52 words
The method of storing and retrieving information from a compact optical storage medium according to claim 14 further comprising the step of using two optical detectors, a voltage comparator and two coherent optical beams of equal intensity as the data reading means for determining the optical polarity of said ferroelectric photorefractive cells.
Claim 19
Dependent Claim
25 words
The method of storing and retrieving information from a compact optical storage medium according to claim 14 wherein said ferroelectric photorefractive material comprises Barium Titanate.
Claim 20
Dependent Claim
24 words
The method of storing and retrieving information, from a compact optical storage medium according to claim 14 wherein said storage medium is substantially transparent.
Claim 21
Dependent Claim
31 words
The method of storing and retrieving information from a compact optical storage medium according to claim 17 wherein said substantially transparent carrier medium comprises a plastic tape arranged for data recording.
Claim 22
Dependent Claim
29 words
The method of storing and retrieving information from a compact optical storage medium according to claim 17 wherein said substantially transparent carrier medium comprises a compact data storage disk.
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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) | 1994-03-25 | 1994-09-24 | 1995-03-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-03-25 | 1998-09-24 | 1999-03-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-03-25 | 2002-09-24 | 2003-03-26 | $7700.00 | Window Closed / Lapsed |