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US3763693A
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Pulsed acousto-optical echo imaging method and apparatus
Assignee: Northrop Grumman Space and Mission Systems Corp
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Filing: 1972-05-30
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Granted: 1973-10-09
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Expires: 1992-05-30
Abstract
Abstract An object is acousto-optically imaged by reflecting acoustic pulses from the object imaged into an acoustic wave transmission medium to produce in the medium reflected acoustic wave pulses each containing information representing an image of the object, and projecting monochromatic light-beam pulses through the acoustic medium across the path of the reflected acoustic pulse waves following generation of the acoustic pulses by the acoustic pulse source in such a way that the light-beam pulses undergo Bragg diffraction by reflected acoustic pulse waves from the object to produce optical images of the object corresponding to the image information contained in the acoustic wave pulses. The described application of the invention involves inspection of a work part for subsurface internal flaws and measuring the subsurfaces depth of any flaws by varying the time delay between each acoustic pulse and the following light-beam pulse until a flaw is imaged and measuring the time delay of the beam pulses which image the flaw.
Inventors
- 👤 P Bhuta
- 👤 R Aprahamian
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 08:15
CPC Classifications
G; G01; G01N; G01N29/00; G01N29/04; G01N29/06
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
176 words
The acousto-optical method of imaging an object which comprises the steps of: selecting a monochromatic light-beam source, an acoustic medium transparent to the light from said beam source, and an acoustic source of given frequency; transmitting acoustic pulses from said acoustic source to said object in such a way that said acoustic pulses reflect from said object into said acoustic medium to produce in said medium reflected acoustic wave pulses each containing information representing an image of said object; and projecting a light-beam pulse from said beam source through said acoustic medium across the path of the reflected acoustic wave pulses following each acoustic pulse from said acoustic source in a manner such that a time delay exists between each acoustic pulse and the following light-beam pulse and light wave fronts of each beam pulse impinge at an acute angle wavefronts of the reflected acoustic wave pulse if any in the path of the beam pulse to produce by Bragg diffraction an optical image corresponding to the image information contained in the respective acoustic wave pulse.
Claim 2
Dependent Claim
176 words
The acousto-optical method of imaging an object which comprises the steps of: selecting a monochromatic light-beam source, an acoustic medium transparent to the light from said beam source, and an acoustic source of given frequency; transmitting acoustic pulses from said acoustic source to said object in such a way that said acoustic pulses reflect from said object into said acoustic medium to produce in said medium reflected acoustic wave pulses each containing information representing an image of said object; and projecting a light-beam pulse from said beam source through said acoustic medium across the path of the reflected acoustic wave pulses following each acoustic pulse from said acoustic source in a manner such that a time delay exists between each acoustic pulse and the following light-beam pulse and light wave fronts of each beam pulse impinge at an acute angle wavefronts of the reflected acoustic wave pulse if any in the path of the beam pulse to produce by Bragg diffraction an optical image corresponding to the image information contained in the respective acoustic wave pulse.
Claim 3
Dependent Claim
20 words
The imaging method according to claim 1 including the additional step of: varying said time delay of each light-beam pulse.
Claim 4
Dependent Claim
20 words
The imaging method according to claim 2 including the additional step of: measuring said time delay of each light-beam pulse.
Claim 5
Dependent Claim
107 words
The imaging method according to claim 1 wherein: said object is a work part to be checked for internal flaws; the surface of said part reflects each incident acoustic pulse to produce in said acoustic medium a leading reflected acoustic wave pulse containing information defining an image of said part surface; and each subsurface flaw in said part reflects each incident acoustic pulse to produce in said acoustic medium a reflected acoustic wave pulse following the respective leading reflected acoustic wave pulse and containing information defining an image of the corresponding flaw, whereby a subsurface flaw may be imaged by providing the proper light-beam pulse time delay.
Claim 6
Dependent Claim
30 words
The imaging method according to claim 4 including the additional step of: varying said delay time of each light-beam pulse to image flaws at different subsurface depths in said part.
Claim 7
Dependent Claim
31 words
The imaging method according to claim 5 including the additional step of: measuring said time delay of each light-beam pulse to permit determination of the subsurface depth of each imaged flaw.
Claim 8
Dependent Claim
50 words
The imaging method according to claim 6 wherein: said acoustic pulses are transmitted through said acoustic medium from said acoustic source across the path of said light-beam pulses, to said part and the acoustic pulses are reflected from said part back through said acoustic medium and across said light-beam path.
Claim 9
Dependent Claim
189 words
Acousto-optical apparatus for imaging an object comprising: a monochromatic light-beam source; an acoUstic medium transparent to the light from said beam source and adapted to be disposed in acoustically coupled relation to said object; means including an acoustic source of given frequency disposed in acoustically coupled relation to said acoustic medium for transmitting acoustic pulses to said object in such a way that said acoustic pulses reflect from said object into said acoustic medium to produce in said medium reflected acoustic wave pulses each containing information representing an image of said object; and means for projecting a light-beam pulse from said beam source through said medium across the path of said reflected acoustic wave pulses following each acoustic pulse from said acoustic source in a manner such that a time delay exists between each acoustic pulse and the following light-beam pulse and light wavefronts of each beam pulse impinge at an acute angle wavefronts of the reflected acoustic wave pulse if any in the path of the beam pulse to produce by Bragg diffraction an optical image corresponding to the image information contained in the respective acoustic wave pulse.
Claim 10
Dependent Claim
189 words
Acousto-optical apparatus for imaging an object comprising: a monochromatic light-beam source; an acoUstic medium transparent to the light from said beam source and adapted to be disposed in acoustically coupled relation to said object; means including an acoustic source of given frequency disposed in acoustically coupled relation to said acoustic medium for transmitting acoustic pulses to said object in such a way that said acoustic pulses reflect from said object into said acoustic medium to produce in said medium reflected acoustic wave pulses each containing information representing an image of said object; and means for projecting a light-beam pulse from said beam source through said medium across the path of said reflected acoustic wave pulses following each acoustic pulse from said acoustic source in a manner such that a time delay exists between each acoustic pulse and the following light-beam pulse and light wavefronts of each beam pulse impinge at an acute angle wavefronts of the reflected acoustic wave pulse if any in the path of the beam pulse to produce by Bragg diffraction an optical image corresponding to the image information contained in the respective acoustic wave pulse.
Claim 11
Dependent Claim
18 words
Acousto-optical imaging apparatus according to claim 8 including: means for varying said time delay of each light-beam pulse.
Claim 12
Dependent Claim
18 words
Acousto-optical imaging apparatus according to claim 9 including: means for measuring said time delay of each light-beam pulse.
Claim 13
Dependent Claim
107 words
Acousto-optical imaging apparatus according to claim 8 wherein: said object is a work part to be checked for internal flaws; the surface of said part reflects each incident acoustic pulse to produce in said acoustic medium a leading reflected acoustic wave pulse containing information defining an image of said part surface; and each subsurface flaw in said part reflects each incident acoustic pulse to produce in said acoustic medium a reflected acoustic wave pulse following the respective leading reflected acoustic wave pulse and containing information defining an image of the corresponding flaw, whereby a subsurface flaw may be imaged by providing the proper light-beam pulse time delay.
Claim 14
Dependent Claim
28 words
Acousto-optical imaging apparatus according to claim 11 including: means for varying said time delay of each light-beam pulse to image flaws at different subsurface depths in said part.
Claim 15
Dependent Claim
29 words
Acousto-optical imaging apparatus according to claim 12 including: means for measuring said time delay of each light-beam pulse to permit determination of the subsurface depth of each imaged flaw.
Claim 16
Dependent Claim
50 words
Acousto-optical imaging apparatus according to claim 13 wherein: said acoustic pulses are transmitted through said acoustic medium from said acoustic source across the path of said light-beam pulses, to said part and the acoustic pulses are reflected from said part back through said acoustic medium and across said light-beam path.
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) | 1976-10-08 | 1977-04-09 | 1977-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-08 | 1981-04-09 | 1981-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-08 | 1985-04-09 | 1985-10-09 | $7700.00 | Window Closed / Lapsed |