US3833893A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Holographic memory including corner reflectors
Assignee: RCA Corp
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Filing: 1972-10-24
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Granted: 1974-09-03
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Expires: 1992-10-24
Abstract
Abstract An electrically and optically accessible memory is disclosed in which binary information is stored in a holographic storage medium with a relatively high packing density by an organization in which lenses are eliminated and corner reflectors are used. A laser beam is directed to an illumination hologram to illuminate an array of controllable corner reflectors each of which reflects to represent a ''''1'''' and does not reflect to represent a ''''O''''. The reflected light returns as an object beam through the illumination hologram to the storage medium, where it interferes with laser light transmitted through the illumination hologram as a reference beam to form a hologram in the storage medium. The stored information is read out by directing the laser beam through the illumination hologram to the storage medium as a reference beam to cause the stored hologram to be read out through the illumination hologram to photosensors associated with the corner reflectors.
Inventors
- 👤 J Rajchman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 18:52
CPC Classifications
G; G03; G03H; G03H1/00; G03H1/26; G11; G11C; G11C13/00; G11C13/04; G11C13/042
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
130 words
A holographic memory system, comprising a page array of controllable corner reflectors each individually controlled to be retroflective or nonretroflective, an array of illumination holograms each being a hologram of said page array of corner reflectors, means to deflect a laser beam to any one of said illumination holograms to cause a reflection of light which illuminates said page array of corner reflectors, and a holographic storage medium for recording many page holograms, said storage medium being positioned to receive a reference beam consisting of said deflected laser beam transmitted through said illumination hologram, and to receive an object beam consisting of a reflection passing through said illumination hologram from said page array of corner reflectors, whereby to record a page array of binary information on said holographic storage medium.
Claim 2
Dependent Claim
130 words
A holographic memory system, comprising a page array of controllable corner reflectors each individually controlled to be retroflective or nonretroflective, an array of illumination holograms each being a hologram of said page array of corner reflectors, means to deflect a laser beam to any one of said illumination holograms to cause a reflection of light which illuminates said page array of corner reflectors, and a holographic storage medium for recording many page holograms, said storage medium being positioned to receive a reference beam consisting of said deflected laser beam transmitted through said illumination hologram, and to receive an object beam consisting of a reflection passing through said illumination hologram from said page array of corner reflectors, whereby to record a page array of binary information on said holographic storage medium.
Claim 3
Dependent Claim
38 words
The combination of claim 1 wherein each of said controllable corner reflectors is constructed with facets in the form of thin reflective membranes which may be distorted from plane reflecting surfaces to light-spreading surfaces by an electrical signal.
Claim 4
Dependent Claim
34 words
The combination of claim 1 wherein said controllable corner reflector is constructed with facets which reflect or not depending on whether electrically-controlled backing members are in the spaced or contacting relation with the facets.
Claim 5
Dependent Claim
16 words
The combination of claim 1 wherein a lens is positioned in front of each corner reflector.
Claim 6
Dependent Claim
30 words
The combination of claim 1 wherein each controllable corner reflector is part of a binary memory unit including a semiconductor bistable circuit having an output controlling the respective corner reflector.
Claim 7
Dependent Claim
22 words
The combination of claim 5 wherein each binary memory unit includes a photosensor connected to the input of the respective bistable circuit.
Claim 8
Dependent Claim
24 words
The combination of claim 6 wherein each said photosensor is positioned to receive a portion of the light directed into a respective corner reflector.
Claim 9
Dependent Claim
88 words
The combination of claim 6 wherein each of said memory units includes two corner reflectors, two photosensors and one bistable semiconductor circuit connected in a balanced arrangement in which one corner reflector is made reflective to write a ''''1'''' and the other corner reflector is made reflective to write a ''''0, '''' whereby, when reading, light is returned to one or the other of the two photosensors depending on the information stored, and the light undesirably returned from the illumination hologram reaches both photosensors in unbalanced cancelling amounts.
Claim 10
Dependent Claim
22 words
The combination of claim 6 wherein said array of illumination holograms and said holographic storage medium are arranged in closely-spaced parallel planes.
Claim 11
Dependent Claim
62 words
The combination of claim 9, and in addition, a polarizing sheet positioned between said array of illumination holograms and said storage medium, means to rotate the polarization of light at a given high frequency is located in the path of said light beam, and said bistable semicoNductor circuits are made responsive to electrical signals, from respective photosensors, having twice said given frequency.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-02 | 1978-03-04 | 1978-09-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-02 | 1982-03-04 | 1982-09-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-02 | 1986-03-04 | 1986-09-03 | $7700.00 | Window Closed / Lapsed |