US3633407A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Acoustic holography with a frequency-shifted reference beam
Assignee: Zenith Electronics LLC
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Filing: 1970-02-16
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Granted: 1972-01-11
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Expires: 1990-02-16
Abstract
Abstract An acoustic interference pattern as manifested upon a compliant surface and caused by an impingent acoustic field carrying image information is visualized into an observable optical interference pattern which is photographed constitutes a hologram of the image information. A source beam of laser light is diffracted from the surface into a subject beam which is thereby modulated with the image information and frequency-shifted from the source light. The subject beam is separated from other diffracted light components and from background scattered noise light and directed to interfere with a reference beam at an angle such that spurious images are minimized. The reference beam is also derived from the source beam and also frequency-shifted for coherence with the subject beam, thereby forming stationary fringes representative of the acoustic interference pattern.
Inventors
- 👤 Robert L Whitman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:12
CPC Classifications
G; G03; G03H; G03H3/00; G02; G02F; G02F1/00; G02F1/01; G02F1/11; Y; Y10; Y10S; Y10S359/00; Y10S359/901
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
183 words
Apparatus for producing a hologram representative of image information borne by an acoustic field, comprising: a source of a coherent monochromatic light beam; means interposed in the path of said source beam for diffracting said beam into at least a pair of output beams differing in frequency, one of which constitutes a reference beam; means interposed in the path of the other of said output beams for diffracting said other output beam into component beams of which one is coherent with said reference beam, and for modulating said one component beam with acoustic field information to constitute a subject beam; means for spatially filtering said subject beam to minimize spurious light in the hologram, comprising means for separating the subject beam from the remainder of said component beams and means for screening out angularly scattered background light about said subject beam; and, means for directing said subject and reference beams to a common area on a display plane to cause the beams to interfere and to form stationary fringes which at any moment constitute an optical hologram bearing said acoustic field image information.
Claim 2
Dependent Claim
183 words
Apparatus for producing a hologram representative of image information borne by an acoustic field, comprising: a source of a coherent monochromatic light beam; means interposed in the path of said source beam for diffracting said beam into at least a pair of output beams differing in frequency, one of which constitutes a reference beam; means interposed in the path of the other of said output beams for diffracting said other output beam into component beams of which one is coherent with said reference beam, and for modulating said one component beam with acoustic field information to constitute a subject beam; means for spatially filtering said subject beam to minimize spurious light in the hologram, comprising means for separating the subject beam from the remainder of said component beams and means for screening out angularly scattered background light about said subject beam; and, means for directing said subject and reference beams to a common area on a display plane to cause the beams to interfere and to form stationary fringes which at any moment constitute an optical hologram bearing said acoustic field image information.
Claim 3
Dependent Claim
31 words
Apparatus as in claim 1, which further includes means for establishing the subject beam at an angular displacement with respect to the reference beam to minimize spurious images in the hologram.
Claim 4
Dependent Claim
84 words
Apparatus as in claim 1, in which said means for separating the subject beam from the remainder of said component beams comprises a reflective surface positioned in the path of the subject beam but out of the paths of the remainder of the component beams; and said means for screening out angularly scattered background light comprises an apertured opaque screen positioned to pass the subject beam while blocking light traveling toward the display plane at angular orientations differing from that of the subject beam.
Claim 5
Dependent Claim
105 words
Apparatus as in claim 1, in which: said means for diffracting said source beam comprises a first light-sound interaction cell operating at a constant acoustic frequency so that said reference beam differs in frequency from said other output beam by the valUe of said acoustic frequency; and, said means for diffracting and modulating the other of said output beams comprises a second light-sound interaction cell operating at the same constant acoustic frequency as said first cell so that said one component beam also differs in frequency from said other component beam by the value of said acoustic frequency to achieve coherence with said reference beam.
Claim 6
Dependent Claim
36 words
Apparatus as in claim 4, in which said second light-sound interaction cell is constructed to receive specimens for acoustic irradiation, so that the subject beam modulation is representative of a characteristic of the specimen under irradiation.
Claim 7
Dependent Claim
66 words
Apparatus as in claim 4, in which said second light-sound interaction cell comprises a compliant surface disposed at an acute angle to the sound wave fronts in the cell for developing surface waves representative of said information-bearing acoustic field, and in which said compliant surface is disposed in the path of said other output beam so that said surface waves operate as a variable diffraction grating.
Claim 8
Dependent Claim
24 words
Apparatus as in claim 6, in which said compliant surface is reflective to said other output beam and is disposed transversely across its path.
Claim 9
Dependent Claim
48 words
Apparatus as in claim 4, in which said one output beam constituting said frequency-shifted reference beam is light of the first order of diffraction produced by said first light-sound interaction cell and said other output beam is light of the zero diffraction order produced by said first cell.
References Cited (Backward Citations)
US2434339A
Cited
US3564904A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-10 | 1975-07-12 | 1976-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-10 | 1979-07-12 | 1980-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-10 | 1983-07-12 | 1984-01-11 | $7700.00 | Window Closed / Lapsed |