US3860346A
Expired / Lapsed
US
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Method of compensating for gross object motion in real time holographic interferometry
Assignee: GCO Inc
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Filing: 1970-02-18
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Granted: 1975-01-14
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Expires: 1990-02-18
Abstract
Abstract To analyze the bond between the skin and core of a metal honeycomb section a hologram is formed of the skin surface and then the skin is heated and a real time holographic interferometry comparison is made. The bowing of the section during the heating results in a high interference fringe frequency over much of the surface making analysis difficult. The angle of the illumination beam and the position of the spacial filter producing the illumination beam are adjusted, relative to the object, to reduce the spacial frequency due to bowing in particular areas of the surface of the object to reveal deformation anamolies identifying defects resulting from failures of bond between the core and skin.
Inventors
- 👤 Leonard A Kersch
- 👤 Edwin B Champagne
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 06:12
CPC Classifications
G; G01; G01B; G01B9/00; G01B9/02; G01B9/021; Y; Y10; Y10S; Y10S359/00; Y10S359/90; Y10S359/902
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
177 words
In the method of defecting structural anomalies in an object by holographic interferometry including the recordation of the wave-fronts reflected from the object while it is illuminated with coherent light at a first time on a hologram and the coherent interferometric comparison of such first wave-fronts as reconstructed from such hologram with second wave-fronts reflected from the object at a second time, after deformation of the object, while it is illuminated by light coherent with that used to reconstruct the first wave-fronts from said hologram, the improvement comprising the step of altering the position of the source of light illuminating the object at said second time relative to the position of the coherent source with respect to the object at said first time so as to modify the interference of said first and second wave-fronts to alter the spacial frequency of interferometric fringes visible on the images produced by the first and second wave-fronts at localized areas on such image, as a result of deformation of the object to allow inspection for deformation anomalies in such area.
Claim 2
Dependent Claim
177 words
In the method of defecting structural anomalies in an object by holographic interferometry including the recordation of the wave-fronts reflected from the object while it is illuminated with coherent light at a first time on a hologram and the coherent interferometric comparison of such first wave-fronts as reconstructed from such hologram with second wave-fronts reflected from the object at a second time, after deformation of the object, while it is illuminated by light coherent with that used to reconstruct the first wave-fronts from said hologram, the improvement comprising the step of altering the position of the source of light illuminating the object at said second time relative to the position of the coherent source with respect to the object at said first time so as to modify the interference of said first and second wave-fronts to alter the spacial frequency of interferometric fringes visible on the images produced by the first and second wave-fronts at localized areas on such image, as a result of deformation of the object to allow inspection for deformation anomalies in such area.
Claim 3
Dependent Claim
72 words
The method of claim 1 wherein the interference fringes occurring on the image produced by said first and second wave-fronts includes first components which are a function of the overall deformation of the section of the object as a result of loading between the first and second times and second components which are a function of deformation caused between said first and second times because of localized structural anomalies in the object.
Claim 4
Dependent Claim
60 words
The method of claim 1 wherein the source of light for illuminating the object is said coherent source and includes a mirror which directs light to the object and the position of the said light relative to the object is altered by modifying the position of the mirror from the position which it assumed during the formation of the hologram.
Claim 5
Dependent Claim
50 words
The method oF claim 1 wherein the light for illuminating the object is said coherent source and includes a pinhole and a lens and the position of the coherent source illuminating the object is altered relative to its position at the first time by moving the pinhole and the lens.
Claim 6
Independent Claim
177 words
The method of real time holographic interferometric analysis of the deformation of an object between two times which includes: positioning the object relative to a coherent illumination source at a first time and forming a record of the light wave-fronts reflected from the object on a hologram by recording on a photographic plate the interference pattern between said light wave-fronts and a reference beam of light from said coherent source; developing and fixing said photographic plate to produce a hologram in the identical position previously occupied by the photographic plate relative to the illumination source, at a second time, after said deformation; viewing the image formed by the wave-front reconstructed from said hologram and the wave-front reflected from said object as it is illuminated by light coherent with said source; and varying the position of the object with respect to said light coherent with said source without varying the relative position of the illuminating source and the hologram in order to modify the spacial frequency of the interference fringes occurring on the object in localized sections thereof.
Claim 7
Independent Claim
177 words
The method of real time holographic interferometric analysis of the deformation of an object between two times which includes: positioning the object relative to a coherent illumination source at a first time and forming a record of the light wave-fronts reflected from the object on a hologram by recording on a photographic plate the interference pattern between said light wave-fronts and a reference beam of light from said coherent source; developing and fixing said photographic plate to produce a hologram in the identical position previously occupied by the photographic plate relative to the illumination source, at a second time, after said deformation; viewing the image formed by the wave-front reconstructed from said hologram and the wave-front reflected from said object as it is illuminated by light coherent with said source; and varying the position of the object with respect to said light coherent with said source without varying the relative position of the illuminating source and the hologram in order to modify the spacial frequency of the interference fringes occurring on the object in localized sections thereof.
Claim 8
Dependent Claim
73 words
The method of claim 5 wherein the coherent source includes a laser and a lens upon which the beam of the laser is incident and which acts to diverge the beam, and the relative position of the object with respect to the illuminating light wave-fronts is varied by moving the lens relative to the object so as to change the radius of curvature of the light wave-fronts at their incidence with the object.
Claim 9
Dependent Claim
52 words
The method of claim 5 wherein said light coherent with said source is derived from apparatus including a mirror and the relative position of the object with respect to said light is varied by moving the mirror so as to change the angle of incidence of the illuminating wavefronts on the object.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-01-13 | 1978-07-15 | 1979-01-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-01-13 | 1982-07-15 | 1983-01-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-01-13 | 1986-07-15 | 1987-01-14 | $7700.00 | Window Closed / Lapsed |