US3612693A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for measurement of surface profile change using a vernier scale in hologram interferometry
Assignee: Gc Optronics Inc
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Filing: 1970-05-15
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Granted: 1971-10-12
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Expires: 1990-05-15
Abstract
Abstract To measure the amount of surface profile change of an object, a hologram is formed by recording on a photographic media the interference pattern between coherent light divided between a uniform, reproducible wave front and mutually coherent light reflected from the object. The virtual image of the object as seen through the hologram formed by the developed photographic media, properly illuminated, is superimposed on the same object with the object being inclined with respect to the virtual image by a predetermined amount. The positions of the object and the virtual image are adjusted to result in the formation of fringes which are spaced apart from one another by a first predetermined scale length. Changes in the profile of a section of the object will result in a shifting of those fringes associated with the unchanged portion. The fringe shift may be measured by employing a second scale having divisions which differ from those of the first scale, in the manner of a vernier scale, such fringe shift being a function of the surface profile change.
Inventors
- 👤 Karl A Stetson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 04:31
CPC Classifications
G; G01; G01B; G01B9/00; G01B9/02; G01B9/021
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
191 words
The method of measuring profile change of a surface of an object comprising: simultaneously exposing a photographic media to a reference beam of coherent light and to an object beam consisting of mutually coherent light reflected from said surface; developing the photographic media so as to form a hologram of said surface; superimposing the virtual image of said surface as seen through the resultant hologram, when the hologram is properly illuminated, with a second image of said surface; shifting said virtual image and said second image of said surface relative to one another forming fringes spaced from each other by a predetermined scale said fringes being a function of the amount of relative shift of said images; subjecting a section of said object to a change of surface profile; observing the shift of the fringes associated with said section; placing a second predetermined scale between a point in said section and a corresponding point in the unchanged portion of said super imposed images, and reading the amount of fringe shift from said second scale at said corresponding point, said fringe shift being a function of the amount of surface profile change.
Claim 2
Independent Claim
191 words
The method of measuring profile change of a surface of an object comprising: simultaneously exposing a photographic media to a reference beam of coherent light and to an object beam consisting of mutually coherent light reflected from said surface; developing the photographic media so as to form a hologram of said surface; superimposing the virtual image of said surface as seen through the resultant hologram, when the hologram is properly illuminated, with a second image of said surface; shifting said virtual image and said second image of said surface relative to one another forming fringes spaced from each other by a predetermined scale said fringes being a function of the amount of relative shift of said images; subjecting a section of said object to a change of surface profile; observing the shift of the fringes associated with said section; placing a second predetermined scale between a point in said section and a corresponding point in the unchanged portion of said super imposed images, and reading the amount of fringe shift from said second scale at said corresponding point, said fringe shift being a function of the amount of surface profile change.
Claim 3
Dependent Claim
20 words
The method of claim 1 wherein the second image of said surface is created in real time by said surface.
Claim 4
Dependent Claim
30 words
The method of claim 1 wherein 1 wherein the second image is formed by shifting said surface to a position which is inclined with respect to said surface''s original position.
Claim 5
Dependent Claim
88 words
The method of claim 1 wherein said second image of said surface occurs as a result of a second exposure of the photographic media simultaneously to a reference beam of coherent light and to an object beam consisting of mutually coherent light reflected from said surface at a time later than the initial exposure of the photographic media after the surface is subjected to said change in profile and before the developing of the photographic media so that the two holograms are recorded in the same photographic media.
Claim 6
Dependent Claim
46 words
The method of claim 1 wherein said superimposed images as viewed through said hologram is recorded on a second photographic media after said fringes associated with the said section have shifted; developing said second photographic media; and measuring said fringe displacement from said second photographic media.
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) | 1974-10-11 | 1975-04-12 | 1975-10-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-10-11 | 1979-04-12 | 1979-10-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-10-11 | 1983-04-12 | 1983-10-12 | $7700.00 | Window Closed / Lapsed |