Patent US3625583A successfully refreshed from Google Patents.
US3625583A
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Erasable hologram
Assignee: International Business Machines Corp
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Filing: 1968-07-15
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Granted: 1971-12-07
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Expires: 1988-07-15
Abstract
Abstract A hologram is produced that is erasable. The erasable storage medium is a thin layer of a europium chalcogenide, i.e., europium oxide, on which the hologram is recorded. The medium chosen on which to record a hologram is erasable and shows no degradation for repetitive storage and erasures. A powerful laser beam is employed for recording purposes in that short powerful light pulses are needed to record on materials having short thermorelaxation times.
Inventors
- 👤 George J Fan
- 👤 James H Greiner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:05
CPC Classifications
G; G03; G03H; G03H1/00; G03H1/04; G03H1/16; G03H1/02; G11; G11C; G11C13/00; G11C13/04; G11C13/042; G11C13/043; G03H2001/026; G03H2222/00; G03H2222/33; G03H2224/00; G03H2224/06; G03H2240/00; G03H2240/20; G03H2240/25; G03H2260/00; G03H2260/30; G03H2260/35
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
150 words
A means for attaining an erasable hologram comprising a storage medium composed of a thermomagnetic film of EuO on a nonmagnetic substrate, means for applying a magnetic field to magnetize said film in a first direction, a magnetic bias means applied to said film tending, but insufficient, to reverse such magnetization, and means for applying a coherent beam of radiant energy through a data-bearing transparency to said EuO film simultaneously with applying said coherent beam as a reference beam onto said film, whereby said radiant energy is effective to switch the magnetization of said film in directions that are related to the intensity of said radiant energy and, in combination with said reference beam, record a phase hologram of said databearing transparency onto said film, said beam of radiant energy activating said thermomagnetic film for a time that is much less than the thermal relaxation time of said thermomagnetic film.
Claim 2
Dependent Claim
150 words
A means for attaining an erasable hologram comprising a storage medium composed of a thermomagnetic film of EuO on a nonmagnetic substrate, means for applying a magnetic field to magnetize said film in a first direction, a magnetic bias means applied to said film tending, but insufficient, to reverse such magnetization, and means for applying a coherent beam of radiant energy through a data-bearing transparency to said EuO film simultaneously with applying said coherent beam as a reference beam onto said film, whereby said radiant energy is effective to switch the magnetization of said film in directions that are related to the intensity of said radiant energy and, in combination with said reference beam, record a phase hologram of said databearing transparency onto said film, said beam of radiant energy activating said thermomagnetic film for a time that is much less than the thermal relaxation time of said thermomagnetic film.
Claim 3
Dependent Claim
18 words
The device of claim 1 wherein said coherent beam of radiant energy is in excess of 105 watts.
Claim 4
Dependent Claim
12 words
The erasable hologram of claim 1 wherein the nonmagnetic substrate is quartz.
References Cited (Backward Citations)
US3368209A
Cited
US3491343A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-12-06 | 1975-06-07 | 1975-12-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-06 | 1979-06-07 | 1979-12-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-06 | 1983-06-07 | 1983-12-07 | $7700.00 | Window Closed / Lapsed |