Patent US3447778A successfully refreshed from Google Patents.
Patent US3620589A successfully refreshed from Google Patents.
US3620589A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Interferometry of transparent objects
Assignee: AT&T Inc
•
Filing: 1970-09-08
•
Granted: 1971-11-16
•
Expires: 1990-09-08
Abstract
Abstract A method and apparatus have been devised for separating information related to the sums of the principal stresses in an object from information related to the differences between the principal stresses. Illustrative apparatus comprises means for rotating by approximately 90* the electric vector of a beam of radiation from the object, means for imaging this radiation to point-for-point coincidence with the object and means for interfering this beam from the object with a second beam that is a reference. Preferably, this second beam is formed by holographic techniques.
Inventors
- 👤 Thomas Dixon Dudderar
- 👤 Richard O'regan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 19:39
CPC Classifications
G; G01; G01B; G01B9/00; G01B9/02; G01B9/021
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
116 words
A method for separating information related to the sums of principal stresses in an object from information related to the differences between principal stresses comprising the steps of: directing through the object when it is in a first condition a first beam of coherent radiation; rotating the electric vector of said beam by approximately 90* and directing the rotated beam back through the object to form an image of the object that is approximately coincident pointfor-point with the object; and interfering the rotated beam from the object with a second beam of phase related coherent radiation to form a first set of isopachic interference fringes representative of the sums of the principal stresses in the object.
Claim 2
Independent Claim
116 words
A method for separating information related to the sums of principal stresses in an object from information related to the differences between principal stresses comprising the steps of: directing through the object when it is in a first condition a first beam of coherent radiation; rotating the electric vector of said beam by approximately 90* and directing the rotated beam back through the object to form an image of the object that is approximately coincident pointfor-point with the object; and interfering the rotated beam from the object with a second beam of phase related coherent radiation to form a first set of isopachic interference fringes representative of the sums of the principal stresses in the object.
Claim 3
Dependent Claim
96 words
The method of claim 1 wherein the second beam of phase related coherent radiation is formed by reconstructing the beam from a hologram that is formed by the steps of: directing through the object when it is in a second condition a third beam of coherent radiation; directing said beam back through the object to form an image of the object that is approximately coincident point-for-point with the object; and interfering the beam after its second passage through the object with a fourth beam of phase related coherent radiation and recording an interference pattern thereby produced.
Claim 4
Dependent Claim
59 words
The method of claim 2 wherein the step of forming the hologram further comprises the step of rotating by approximately 90* the electric vector of the third beam of coherent radiation after said beam is directed through the object but before said beam is directed back through the object to form the image that is coincident with the object.
Claim 5
Dependent Claim
97 words
The method of claim 1 further comprising the steps of: making a record of the set of interference fringes formed by the interference of the rotated beam and the second beam of coherent radiation; directing through the object when it is in a second condition a third beam of coherent radiation; directing said beam back through the object to form an image of the object that is approximately coincident point-for-point with the object; and interfering the beam after its second passage through the object with a fourth beam of phase related coherent radiation reconstructed from said record.
Claim 6
Dependent Claim
59 words
The method of claim 4 further comprising the step of rotating by approximately 90* the electric vector of the third beam of coherent radiation after said beam is directed through the object when it is in its second condition but before said beam is directed back through the object to form the image that is coincident with the object.
Claim 7
Dependent Claim
110 words
The method of claim 1 further comprising the steps of: directing through the object when it is in a second condition a third beam of coherent radiation; rotating the electric vector of said beam by approximately 90* and directing the rotated beam back through the object to form an image of the object that is approximately coincident point-for-point with the object; interfering the rotated beam from the object with a fourth beam of phase related coherent radiation to form a second set of interference fringes representative of the sums of the principal stresses in the object in its second condition; and recording both sets of fringes on a recording medium.
Claim 8
Dependent Claim
9 words
A hologram formed by the method of claim 6.
Claim 9
Dependent Claim
94 words
The method of claim 1 further comprising the steps of: directing through the object when it is in a second condition a third beam of coherent radiation; directing said beam back through the object to form an image of the object that is approximately coincident point-for-point with the object; interfering the beam after its second passage through the object with a fourth beam of phase related coherent radiation to form a second set of intErference fringes representative of the object in its second condition; and recording both sets of fringes on a recording medium.
Claim 10
Dependent Claim
9 words
A hologram formed by the method of claim 8.
Claim 11
Dependent Claim
18 words
A hologram formed by recording the first set of interference fringes formed by the method of claim 1.
Claim 12
Dependent Claim
73 words
The method of claim 1 wherein the first beam of coherent radiation is circularly polarized further comprising the steps of: forming from the first beam of radiation a fifth beam of radiation after the first beam is directed through the object but before its electric vector is rotated; and directing said fifth beam through a polariscope to form a set of isochromatic fringes representative of the differences between principal stresses in the object.
Claim 13
Dependent Claim
113 words
Apparatus for separating information related to the sums of principal stresses in an object from information related to the differences between principal stresses comprising: means for directing through the object to be studied a first beam of coherent radiation; means for rotating the electric vector of said beam by approximately 90* and directing the rotated beam back through the object to form an image of the object that is approximately coincident point-for-point with the object; and means for interfering the rotated beam from the object with a second beam of phase related coherent radiation to form a set of isopachic interference fringes representative of the sums of the principal stress in the object.
Claim 14
Dependent Claim
113 words
Apparatus for separating information related to the sums of principal stresses in an object from information related to the differences between principal stresses comprising: means for directing through the object to be studied a first beam of coherent radiation; means for rotating the electric vector of said beam by approximately 90* and directing the rotated beam back through the object to form an image of the object that is approximately coincident point-for-point with the object; and means for interfering the rotated beam from the object with a second beam of phase related coherent radiation to form a set of isopachic interference fringes representative of the sums of the principal stress in the object.
Claim 15
Dependent Claim
89 words
The apparatus of claim 12 wherein the means for rotating the electric vector and directing the rotated beam back through the object to form an image comprises: first and second lenses and a reflecting surface in the path of the beam from the object, said lenses being spaced apart by approximately the sum of their focal lengths; and means for rotating the electric vector of the beam located between the first and second lenses at a distance from the first lens that is approximately equal to its focal length.
Claim 16
Dependent Claim
40 words
The apparatus of claim 13 wherein the focal lengths of the lenses and the distances of the object and the reflecting surface from the lenses are such that the lenses form an image of the object near the reflecting surface.
Claim 17
Dependent Claim
47 words
The apparatus of claim 14 wherein the lenses and reflecting surface are oriented so that a beam of radiation from the object that is reflected back to the object to form an image coincident with it passes through the means for rotating the electric vector only once.
Claim 18
Dependent Claim
19 words
The apparatus of claim 15 wherein the means for rotating the electric vector comprises a quartz 90* polarization rotator.
Claim 19
Dependent Claim
45 words
The apparatus of claim 14 wherein the means for rotating the electric vector is a Faraday rotator and the beam from the object that is reflected back to the object to form an image that is coincident with it passes through the Faraday rotator twice.
Claim 20
Dependent Claim
57 words
The apparatus of claim 12 further comprising a beam splitter located in the path of the first beam of radiation and a polariscope located in the path of the beam formed from the first beam by the beam splitter for forming a set of isochromatic fringes representative of the differences between the principal stresses in the object.
References Cited (Backward Citations)
US3561838A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-11-15 | 1975-05-17 | 1975-11-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-15 | 1979-05-17 | 1979-11-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-15 | 1983-05-17 | 1983-11-16 | $7700.00 | Window Closed / Lapsed |