US3720921A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Recording in reversible, photochromic medium
Assignee: International Business Machines Corp
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Filing: 1970-07-14
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Granted: 1973-03-13
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Expires: 1990-07-14
Abstract
Abstract Interfering radiations of substantially coherent electromagnetic radiation of a wave length within a range to which a layer of photochromic material is sensitive are transmitted in different directions through a layer of the material in selected regions. The interfering radiations in each region produce antinodes which form peak energy levels to sensitize the photochromic material in spaced, parallel surfaces of a periodic structure having altered transmission and reflective properties. The sensitized regions constituting the recorded information may be read by radiation of a lower energy level or of a wave length outside the range of sensitivity directed to the regions, the reflected radiation being detected to represent the recorded information. A plurality of interfering beams may be transmitted in different directions in the same region to produce different recordings and may be detected by the same radiations. The photochromic material may be restored to its original state by radiation of a wave length in a third range, so that such radiation may be used to erase recording in any region.
Inventors
- 👤 R Schools
- 👤 G Sincerbox
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 00:43
CPC Classifications
G; G11; G11C; G11C13/00; G11C13/04; G11C13/042; G11C13/045
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
167 words
A system of recording information in selected regions of a recording medium comprising a layer of reversible, photochromic material which is sensitive to alteration of its radiation transmission and reflection properties by electromagnetic radiation of a wave length within a first range and above a certain energy level, and is insensitive to radiation of a wave length within a second range, means to transmit a pair of beams of substantially coherent monochromatic electromagnetic radiation within said first range below said certain energy level in different directions through the opposite sides of said layer in a single region of said medium so as to form standing waves of interfering radiation through said layer in said region, the peak energy level of the antinodes of said interfering standing waves being above said certain energy level to alter said transmission and reflection properties of said medium in parallel, spaced surfaces through said layer, so that said pair of interfering radiations forms a periodic structure in said region of said layer.
Claim 2
Independent Claim
167 words
A system of recording information in selected regions of a recording medium comprising a layer of reversible, photochromic material which is sensitive to alteration of its radiation transmission and reflection properties by electromagnetic radiation of a wave length within a first range and above a certain energy level, and is insensitive to radiation of a wave length within a second range, means to transmit a pair of beams of substantially coherent monochromatic electromagnetic radiation within said first range below said certain energy level in different directions through the opposite sides of said layer in a single region of said medium so as to form standing waves of interfering radiation through said layer in said region, the peak energy level of the antinodes of said interfering standing waves being above said certain energy level to alter said transmission and reflection properties of said medium in parallel, spaced surfaces through said layer, so that said pair of interfering radiations forms a periodic structure in said region of said layer.
Claim 3
Independent Claim
167 words
A system of recording information in selected regions of a recording medium comprising a layer of reversible, photochromic material which is sensitive to alteration of its radiation transmission and reflection properties by electromagnetic radiation of a wave length within a first range and above a certain energy level, and is insensitive to radiation of a wave length within a second range, means to transmit a pair of beams of substantially coherent monochromatic electromagnetic radiation within said first range below said certain energy level in different directions through the opposite sides of said layer in a single region of said medium so as to form standing waves of interfering radiation through said layer in said region, the peak energy level of the antinodes of said interfering standing waves being above said certain energy level to alter said transmission and reflection properties of said medium in parallel, spaced surfaces through said layer, so that said pair of interfering radiations forms a periodic structure in said region of said layer.
Claim 4
Independent Claim
167 words
A system of recording information in selected regions of a recording medium comprising a layer of reversible, photochromic material which is sensitive to alteration of its radiation transmission and reflection properties by electromagnetic radiation of a wave length within a first range and above a certain energy level, and is insensitive to radiation of a wave length within a second range, means to transmit a pair of beams of substantially coherent monochromatic electromagnetic radiation within said first range below said certain energy level in different directions through the opposite sides of said layer in a single region of said medium so as to form standing waves of interfering radiation through said layer in said region, the peak energy level of the antinodes of said interfering standing waves being above said certain energy level to alter said transmission and reflection properties of said medium in parallel, spaced surfaces through said layer, so that said pair of interfering radiations forms a periodic structure in said region of said layer.
Claim 5
Dependent Claim
24 words
A system as claimed in claim 1, and means for reflecting radiation within said second range from said medium to read the recorded information.
Claim 6
Independent Claim
148 words
A system of recording information selectively in selected regions of a recording medium comprising a layer of reversible, photochromic material which is sensitive to alteration of its radiation transmission and reflection properties by electromagnetic radiation of a wave length in a first range and above a certain energy level and is insensitive to radiation of a wave length in a second range, means to transmit substantially coherent electromagnetic radiations within said first range and below said certain energy level in diffeRent directions through said layer to alter said properties of said material in selected regions to represent recorded information by producing interfering radiations through said layer in said regions, the antinodes of said radiations forming peak energy levels above said certain energy level within said first range, and means to read the information recorded in said selected regions by radiation of a wave length in said second range.
Claim 7
Independent Claim
148 words
A system of recording information selectively in selected regions of a recording medium comprising a layer of reversible, photochromic material which is sensitive to alteration of its radiation transmission and reflection properties by electromagnetic radiation of a wave length in a first range and above a certain energy level and is insensitive to radiation of a wave length in a second range, means to transmit substantially coherent electromagnetic radiations within said first range and below said certain energy level in diffeRent directions through said layer to alter said properties of said material in selected regions to represent recorded information by producing interfering radiations through said layer in said regions, the antinodes of said radiations forming peak energy levels above said certain energy level within said first range, and means to read the information recorded in said selected regions by radiation of a wave length in said second range.
Claim 8
Dependent Claim
31 words
A system as claimed in claim 3, and means to restore said medium to its original state by exposing said medium to radiation of a wave length in a third range.
Claim 9
Independent Claim
170 words
A system of recording information in selected regions of a recording medium comprising a layer of reversible, photochromic material which is sensitive to alteration of its radiation transmission and reflection properties by electromagnetic radiation of a wave length within a first range and above a certain energy level, and is insensitive to radiation of a wave length within a second range, means to transmit a plurality of pairs of beams of substantially coherent monochromatic electromagnetic radiation within said first range and below said certain energy level in different directions through the opposite sides of said layer in a single region of said medium so that each pair forms standing waves of interfering radiation through said layer in said region, the peak energy level of the antinodes of said standing waves being above said certain energy level to alter said transmission and reflection properties of said medium in parallel, spaced surfaces through said layer, so that each pair of interfering radiations forms a periodic structure in said region of said layer.
Claim 10
Independent Claim
170 words
A system of recording information in selected regions of a recording medium comprising a layer of reversible, photochromic material which is sensitive to alteration of its radiation transmission and reflection properties by electromagnetic radiation of a wave length within a first range and above a certain energy level, and is insensitive to radiation of a wave length within a second range, means to transmit a plurality of pairs of beams of substantially coherent monochromatic electromagnetic radiation within said first range and below said certain energy level in different directions through the opposite sides of said layer in a single region of said medium so that each pair forms standing waves of interfering radiation through said layer in said region, the peak energy level of the antinodes of said standing waves being above said certain energy level to alter said transmission and reflection properties of said medium in parallel, spaced surfaces through said layer, so that each pair of interfering radiations forms a periodic structure in said region of said layer.
Claim 11
Dependent Claim
40 words
A system as claimed in claim 5, and means to reflect radiation within said second range from the several structures to sense the recorded information, and means to sense the reflected radiation according to the direction of the recording radiation.
Claim 12
Dependent Claim
68 words
A system as claimed in claim 5, in which means are provided to transmit a plurality of pairs of interfering beams through said layer within a region to form a plurality of periodic structures of spaced surfaces through said layer, and said means to direct a beam of a wave length within said second range to any of said regions produces reflections from each of said periodic structures.
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) | 1976-03-12 | 1976-09-11 | 1977-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-12 | 1980-09-11 | 1981-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-12 | 1984-09-11 | 1985-03-13 | $7700.00 | Window Closed / Lapsed |