US3924924A
Expired / Lapsed
US
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Holographic memory utilizing a changeable phase object and coherent subtraction
Assignee: Hitachi Ltd
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Filing: 1973-09-18
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Granted: 1975-12-09
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Expires: 1993-09-18
Abstract
Abstract A pattern generating device includes a plurality of biaxial birefringent irregular ferroelectric crystal elements, each crystal being cut such that mutually opposing planes are normal to any one of the a-, b- and c-axis that a thickness between the planes is that of a half-wave plate, said crystal elements being arranged in the form of a matrix on an identical plane normal to incident light, a required information pattern being recorded on a photosensitive medium in a manner that elements corresponding to the information pattern are manipulated by a threshold voltage applied to the Z-planes of the respective elements, so that a large-capacity information recording method can be carried out.
Inventors
- 👤 Akira Fukuhara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:56
CPC Classifications
G; G11; G11C; G11C13/00; G11C13/04; G11C13/042; G11C13/044; G02; G02F; G02F1/00; G02F1/01; G02F1/03; G02F1/05
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
58 words
applying a voltage sufficient to invert spontaneous polarization by 180*, separately to reversible modulator elements of a bit group, generating a predetermined information pattern and to reversible modulator elements of a bit group, generating no pattern among said respective reversible phase-modulating elements which constitute said pattern generating device, said spontaneous polarization having random polarities among the respective bits;
Claim 2
Dependent Claim
58 words
applying a voltage sufficient to invert spontaneous polarization by 180*, separately to reversible modulator elements of a bit group, generating a predetermined information pattern and to reversible modulator elements of a bit group, generating no pattern among said respective reversible phase-modulating elements which constitute said pattern generating device, said spontaneous polarization having random polarities among the respective bits;
Claim 3
Dependent Claim
142 words
A hologram preparing apparatus comprising: an interferable-light source; polarization means which is arranged in an optical path of light beams emitted by said interferable-light source, and which converts said interferable light beam into a linearly polarized beam; a beam splitter which is arranged in an optical path of said linearly polarized beam converted by said polarizing means; a pattern generating device including a plurality of reversible phase-modulating elements each comprising an irregular ferroelectric crystal plate in which each set of mutually opposing end planes are normal to one of a-, b- and c-axis, and a thickness between said end planes is prescribed with respect to a difference Delta n in the refractive index between light beams having a wavelength lambda and having their polarization planes respectively parallel to said a- and b-axis within the crystal and to a positive integer P by
Claim 4
Dependent Claim
142 words
A hologram preparing apparatus comprising: an interferable-light source; polarization means which is arranged in an optical path of light beams emitted by said interferable-light source, and which converts said interferable light beam into a linearly polarized beam; a beam splitter which is arranged in an optical path of said linearly polarized beam converted by said polarizing means; a pattern generating device including a plurality of reversible phase-modulating elements each comprising an irregular ferroelectric crystal plate in which each set of mutually opposing end planes are normal to one of a-, b- and c-axis, and a thickness between said end planes is prescribed with respect to a difference Delta n in the refractive index between light beams having a wavelength lambda and having their polarization planes respectively parallel to said a- and b-axis within the crystal and to a positive integer P by
Claim 5
Dependent Claim
58 words
imparting a voltage sufficient to invert spontaneous polarization by 180*, separately to reversible phase modulating elements of a bit group generating a predetermined information pattern and to reversible phase-modulating elements of a bit group generating no pattern among said respective reversible phase-modulating elements of said pattern generating device, said spontaneous polarization having random polarities among the respective bits;
Claim 6
Dependent Claim
58 words
imparting a voltage sufficient to invert spontaneous polarization by 180*, separately to reversible phase modulating elements of a bit group generating a predetermined information pattern and to reversible phase-modulating elements of a bit group generating no pattern among said respective reversible phase-modulating elements of said pattern generating device, said spontaneous polarization having random polarities among the respective bits;
Claim 7
Dependent Claim
31 words
causing said hologram recording medium of said hologram preparing apparatus to sense a hologram pattern image of the pattern image of said pattern generating device having undergone the above step (1);
Claim 8
Dependent Claim
31 words
causing said hologram recording medium of said hologram preparing apparatus to sense a hologram pattern image of the pattern image of said pattern generating device having undergone the above step (1);
Claim 9
Dependent Claim
19 words
focussing the pattern image of said pattern generating device, having undergone the above step (1), to said hologram medium;
Claim 10
Dependent Claim
19 words
focussing the pattern image of said pattern generating device, having undergone the above step (1), to said hologram medium;
Claim 11
Dependent Claim
19 words
A hologram preparing apparatus according to claim 1, wherein said irregular ferroelectric crystal plate is made of Gd2 (MoO4)3.
Claim 12
Dependent Claim
112 words
A hologram preparing apparatus comprising: an interferable-light source; a beam splitter which is arranged in an optical path of an interferable light beam emitted from said interferable-light source; a pattern generating device including a plurality of reversible phase-modulating elements each comprising an irregular ferroelectric crystal plate in which each set of mutually opposing end planes are normal to one of a-, b- and caxis, and a thickness between said end planes is prescribed with respect to a difference Delta n in the refractive index between light beams having wavelength lambda and having their poLarization planes respectively parallel to said a- and b-axis within the crystal and to a positive integer P by
Claim 13
Dependent Claim
112 words
A hologram preparing apparatus comprising: an interferable-light source; a beam splitter which is arranged in an optical path of an interferable light beam emitted from said interferable-light source; a pattern generating device including a plurality of reversible phase-modulating elements each comprising an irregular ferroelectric crystal plate in which each set of mutually opposing end planes are normal to one of a-, b- and caxis, and a thickness between said end planes is prescribed with respect to a difference Delta n in the refractive index between light beams having wavelength lambda and having their poLarization planes respectively parallel to said a- and b-axis within the crystal and to a positive integer P by
Claim 14
Dependent Claim
24 words
focussing the pattern image of said pattern generating device, having undergone the step (3), to said hologram recording medium having undergone the step (2).
Claim 15
Dependent Claim
24 words
focussing the pattern image of said pattern generating device, having undergone the step (3), to said hologram recording medium having undergone the step (2).
Claim 16
Dependent Claim
19 words
A hologram preparing apparatus according to claim 3, wherein said irregular ferroelectric crystal plate is made of Gd2 (MoO4)3.
Claim 17
Dependent Claim
21 words
causing said hologram recording medium, having undergone the step (2), to doubly sense the hologram image of said pattern generating device.
Claim 18
Dependent Claim
21 words
causing said hologram recording medium, having undergone the step (2), to doubly sense the hologram image of said pattern generating device.
Claim 19
Dependent Claim
21 words
A method of preparing a hologram according to claim 5, wherein said irregular ferroelectric crystal plate is made of Gd2 (MoO4)3.
Claim 20
Independent Claim
120 words
A method of preparing a hologram with a hologram preparing apparatus including: an interferable-light source; a beam splitter which is arranged in an optical path of an interferable light beam emitted from said interferable-light source; a pattern generating device including a plurality of reversible phase-modulating elements each comprising an irregular ferroelectric crystal plate in which each set of mutually opposing end planes are normal to one of A, b- and c-axis, and a thickness between said end planes is prescribed with respect to a difference Delta n in the refractive index between light beams having a wavelength lambda and having their polarization planes respectively parallel to said a- and b-axis within the crystal and to a positive integer P by
Claim 21
Independent Claim
120 words
A method of preparing a hologram with a hologram preparing apparatus including: an interferable-light source; a beam splitter which is arranged in an optical path of an interferable light beam emitted from said interferable-light source; a pattern generating device including a plurality of reversible phase-modulating elements each comprising an irregular ferroelectric crystal plate in which each set of mutually opposing end planes are normal to one of A, b- and c-axis, and a thickness between said end planes is prescribed with respect to a difference Delta n in the refractive index between light beams having a wavelength lambda and having their polarization planes respectively parallel to said a- and b-axis within the crystal and to a positive integer P by
Claim 22
Dependent Claim
21 words
A method of preparing a hologram according to claim 7, wherein said irregular ferroelectric crystal plate is made of Gd2 (MoO4)3.
References Cited (Backward Citations)
US3586415A
Cited
US3559185A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-08 | 1979-06-09 | 1979-12-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-08 | 1983-06-09 | 1983-12-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-08 | 1987-06-09 | 1987-12-09 | $7700.00 | Window Closed / Lapsed |