US4687720A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Side lobe suppression in holograms using pre-exposure
Assignee: Dai Nippon Printing Co Ltd
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Filing: 1984-12-21
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Granted: 1987-08-18
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Expires: 2004-12-21
Abstract
Abstract A holographic recording medium is treated to eliminate side lobes. The method involves exposing opposed surfaces of the medium with filtered incoherent light either before or after a holographic exposure with coherent light. The incoherent exposure produces controlled desensitization of the medium, resulting in a sensitivity profile which increases continuously to a maximum near the center of the layer. A hologram recorded in the layer has a refractive index modulation which is high in the center of the layer and which decreases toward the surfaces of the layer.
Inventors
- 👤 John E. Wreede
- 👤 James A. Arns
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 20:35
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/004; G11B7/0065; G03; G03C; G03C1/00; G03C1/66; G03H; G03H1/00; G03H1/04; G03H1/18
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
87 words
Method of making a hologram having an efficiency curve with substantially reduced side lobes comprising: preparing a thin layer of holographic recording medium having opposed surfaces; exposing said surfaces of the layer to filtered incoherent light in a manner to produce a sensitivity profile therein which is substantially zero at said surfaces and increases substantially continuously to a maximum in the vicinity of the center of the layer; and exposing said layer having said sensitivity profile to coherent light beams to record a hologram fringe pattern therein.
Claim 2
Dependent Claim
87 words
Method of making a hologram having an efficiency curve with substantially reduced side lobes comprising: preparing a thin layer of holographic recording medium having opposed surfaces; exposing said surfaces of the layer to filtered incoherent light in a manner to produce a sensitivity profile therein which is substantially zero at said surfaces and increases substantially continuously to a maximum in the vicinity of the center of the layer; and exposing said layer having said sensitivity profile to coherent light beams to record a hologram fringe pattern therein.
Claim 3
Dependent Claim
11 words
The method of claim 1 wherein the layer is dichromated gelatin.
Claim 4
Dependent Claim
15 words
The method of claim 2 wherein the incoherent light is emitted from a tungsten lamp.
Claim 5
Dependent Claim
26 words
The method of claim 3 wherein the incoherent light is filtered through a National Bureau of Standards standard 5-56 filter which peaks at about 440 nanometers.
Claim 6
Dependent Claim
28 words
The method of claim 4 wherein the exposure to incoherent light has a duration of about 40 seconds and an intensity of about 4.0 milliwatts per square centimeter.
Claim 7
Dependent Claim
23 words
The method of claim 2 wherein the incoherent light is emitted from a mercury arc lamp and is filtered at about 366 nanometers.
Claim 8
Dependent Claim
21 words
The method of claim 1 wherein said incoherent light is incident upon both of said opposed surfaces at external faces thereof.
Claim 9
Dependent Claim
36 words
A hologram comprising a thin layer of holographic recording medium having opposed surfaces, said medium having a light sensitivity profile which increases substantially continuously to a maximum in the vicinity of the center of the layer.
Claim 10
Dependent Claim
36 words
A hologram comprising a thin layer of holographic recording medium having opposed surfaces, said medium having a light sensitivity profile which increases substantially continuously to a maximum in the vicinity of the center of the layer.
Claim 11
Dependent Claim
35 words
The hologram of claim 8 further having a hologram fringe pattern recorded in said medium exhibiting a fringe modulation which increases substantially continuously to a maximum in the vicinity of the center of the layer.
Claim 12
Dependent Claim
16 words
The hologram of claim 8 wherein the light sensitivity profile is substantially zero at said surfaces.
Claim 13
Dependent Claim
15 words
The hologram of claim 9 wherein the fringe modulation is substantially zero at said surfaces.
Claim 14
Dependent Claim
52 words
Method for making a holographic recording structure comprising: preparing a thin layer of holographic recording medium having opposed surfaces; and exposing said surfaces to filtered incoherent light in a manner to produce a sensitivity profile therein which increases substantially continuously to a maximum in the vicinity of the center of the layer.
Claim 15
Dependent Claim
52 words
Method for making a holographic recording structure comprising: preparing a thin layer of holographic recording medium having opposed surfaces; and exposing said surfaces to filtered incoherent light in a manner to produce a sensitivity profile therein which increases substantially continuously to a maximum in the vicinity of the center of the layer.
Claim 16
Dependent Claim
15 words
The method of claim 12 wherein the sensitivity profile is substantially zero at said surfaces.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-08-17 | 1991-02-16 | 1991-08-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-08-17 | 1995-02-16 | 1995-08-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-08-17 | 1999-02-16 | 1999-08-18 | $7700.00 | Window Closed / Lapsed |