Patent US3779625A successfully refreshed from Google Patents.
US3779625A
Expired / Lapsed
US
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Holographic recording with two groups of differently oriented plane polarized object illumination beams
Assignee: Siemens AG
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Filing: 1972-03-06
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Granted: 1973-12-18
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Expires: 1992-03-06
Abstract
Abstract The present invention is directed to a method and apparatus for recording information on a holographic storage medium which information is presented in an information mask characterized by projecting a coherent light beam, which has been polarized in one direction, through a mask which changes the direction of polarization of discrete portions of the light beam which is subsequently divided into a plurality of light beams by a mosaic of lens. The plurality of light beams are projected through the information mask, which modulates the beam with information contained in the mask, and onto the holographic storage medium where a reference beam is superimposed therewith to record the information. The polarization mask is provided with statistically distributed raster of apertures so that a portion of the light beam passing through the material of the mask has its direction of polarization rotated relative to the direction of polarization of the other portion which passes through the apertures. The angle between the directions of polarization of the two portion of the light beam is in either a range of 80* to 100* and preferably 90* or a range of 170* to 190* and preferably 180*.
Inventors
- 👤 M Lang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 18:02
CPC Classifications
G; G11; G11C; G11C13/00; G11C13/04; G11C13/042; G03; G03H; G03H1/00; G03H1/04; G03H1/0402; G03H1/041; G03H1/26; G03H1/30; G03H1/0465; G03H2210/00; G03H2210/10; G03H2222/00; G03H2222/31; G03H2223/00; G03H2223/17; G03H2223/19
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
193 words
In a method for recording information in a holographic storage medium wherein the information which is to be recorded is provided on an information mask in a raster-like pattern, the information being recorded by providing a beam of coherent light, dividing the beam of coherent light into a plurality of individual beams and projecting the plurality of individual beams through the information mask onto the storage medium, with the mask modulating the individual beams in accordance with the information stored in the raster-like pattern and superimposing a reference beam with the modulated beams on the medium to record the information as a hologram, the improvement comprising polarizing all of the coherent light in one direction and prior to projecting the individual beams through the information mask changing the direction of polarization of a portion of the individual beams so that the individual beams projected through the mask are in two substantially equal groups of beams with one group having a polarization direction forming a substantial angle with the polarization direction of the other group, said reference beam being plane polarized in a direction capable of interfering with both groups of said coherent beams.
Claim 2
Dependent Claim
193 words
In a method for recording information in a holographic storage medium wherein the information which is to be recorded is provided on an information mask in a raster-like pattern, the information being recorded by providing a beam of coherent light, dividing the beam of coherent light into a plurality of individual beams and projecting the plurality of individual beams through the information mask onto the storage medium, with the mask modulating the individual beams in accordance with the information stored in the raster-like pattern and superimposing a reference beam with the modulated beams on the medium to record the information as a hologram, the improvement comprising polarizing all of the coherent light in one direction and prior to projecting the individual beams through the information mask changing the direction of polarization of a portion of the individual beams so that the individual beams projected through the mask are in two substantially equal groups of beams with one group having a polarization direction forming a substantial angle with the polarization direction of the other group, said reference beam being plane polarized in a direction capable of interfering with both groups of said coherent beams.
Claim 3
Dependent Claim
61 words
In a method according to claim 1, wherein the Angle included by the two polarization directions lies in a range of between 80* and 100*, and wherein the step of superimposing a reference beam includes providing a reference beam having a direction of polarization which is at an angle of approximately 45* to the direction of polarization of the two groups.
Claim 4
Dependent Claim
25 words
In a method according to claim 1, wherein the angle included by the two polarization directions lies in a range of between 170* and 190*.
Claim 5
Independent Claim
168 words
An apparatus for recording information on a holographic storage medium wherein the information to be recorded is stored in a raster-like pattern on an information mask, the apparatus comprising means for providing a plane polarized coherent beam of light, means rotating the direction of polarization of discrete portions of said coherent beam, means for dividing the coherent beam into a plurality of coherent beams, said plurality of beams forming two substantially equal groups with one group of coherent beams having a direction of polarization at the angle to the direction of polarization of the other group, said dividing means projecting the plurality of coherent beams through the information mask onto the storage medium with the mask modulating the beams in accordance with the information stored thereon, and means for directing a reference beam plane polarized in a direction capable of interfering with both groups of said coherent beams to superimpose with the modulated beams on the storage medium to record the information in the form of holograms thereon.
Claim 6
Independent Claim
168 words
An apparatus for recording information on a holographic storage medium wherein the information to be recorded is stored in a raster-like pattern on an information mask, the apparatus comprising means for providing a plane polarized coherent beam of light, means rotating the direction of polarization of discrete portions of said coherent beam, means for dividing the coherent beam into a plurality of coherent beams, said plurality of beams forming two substantially equal groups with one group of coherent beams having a direction of polarization at the angle to the direction of polarization of the other group, said dividing means projecting the plurality of coherent beams through the information mask onto the storage medium with the mask modulating the beams in accordance with the information stored thereon, and means for directing a reference beam plane polarized in a direction capable of interfering with both groups of said coherent beams to superimpose with the modulated beams on the storage medium to record the information in the form of holograms thereon.
Claim 7
Dependent Claim
31 words
An apparatus according to claim 4, wherein the means for rotating the direction of polarization is a polarizing mask having discrete portions of one thickness and discrete portions of another thickness.
Claim 8
Dependent Claim
16 words
An apparatus according to claim 5 wherein the polarizing mask consists of an optically active material.
Claim 9
Dependent Claim
29 words
An apparatus according to claim 4 wherein the means for rotating the direction of polarization comprises a mask of material having apertures therethrough arranged in statistically distributed raster positions.
Claim 10
Dependent Claim
15 words
An apparatus according to claim 7, wherein the polarizing mask consists of optically active material.
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) | 1976-12-17 | 1977-06-18 | 1977-12-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-17 | 1981-06-18 | 1981-12-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-17 | 1985-06-18 | 1985-12-18 | $7700.00 | Window Closed / Lapsed |