US3879133A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for comparing two objects having similar shapes and dimensions
Assignee: Compagnie Electro Mecanique SA
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Filing: 1973-12-20
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Granted: 1975-04-22
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Expires: 1993-12-20
Abstract
Abstract A method and apparatus for comparing two objects having similar shapes and dimensions wherein one of the objects is illuminated by a collimated light beam whose intensity is modulated in a direction transverse thereto at a spatial frequency 1/p. The modulated light beam generates a lattice of alternately dark and light parallel bands similar to interference fringes having a pitch p on the illuminated surface of the object having a configuration in the manner of contour lines determined by the relief of the illuminated side of the object. The other object is thereafter substituted for the first one and in the same position, and is similarly illuminated by the same beam but wherein the intensity modulation has been phase-shifted by 180*. The respective images of the two objects are optically superimposed and from which is then obtained only the differential component of the image which is modulated with a spatial frequency 1/p. Apparatus for carrying out the method can be either (1) photographic in which case the superimposed images of the two objects are established by development on a photo-sensitive negative which is light-transmissive in conjunction with a lens which transmits only the differential component in the negative to a photographic plate, or (2) electronically by means of a TV camera and related components by which the respective video images are added and passed to a visual display device such as a cathode ray tube via a filter having a pass band transmitting only the differential signal component which is modulated by the time frequency v/p wherein v constitutes the linear sweep speed of the TV camera.
Inventors
- 👤 Ernst Mathieu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 23:06
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/60
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
133 words
A method for comparing two three-dimensional objects having similar shapes and dimensions which comprises: illuminating a side of one of the objects by a collimated light beam whose intensity is modulated in a direction transverse thereto at a spatial frequency of 1/p, said modulated light beam generating on the illuminated side of the object a lattice of alternately dark and light parallel bands similar to interference fringes having a configuration in the manner of contour lines determined by the relief of the illuminated side of the object and pitch p, similarly illuminating the other object but wherein the intensity modulation is phase-shifted by 180*, optically superimposing images of the illuminated sides of the two objects, and obtaining from the superimposed images the differential component thereof which is modulated at the spatial frequency 1/p.
Claim 2
Independent Claim
133 words
A method for comparing two three-dimensional objects having similar shapes and dimensions which comprises: illuminating a side of one of the objects by a collimated light beam whose intensity is modulated in a direction transverse thereto at a spatial frequency of 1/p, said modulated light beam generating on the illuminated side of the object a lattice of alternately dark and light parallel bands similar to interference fringes having a configuration in the manner of contour lines determined by the relief of the illuminated side of the object and pitch p, similarly illuminating the other object but wherein the intensity modulation is phase-shifted by 180*, optically superimposing images of the illuminated sides of the two objects, and obtaining from the superimposed images the differential component thereof which is modulated at the spatial frequency 1/p.
Claim 3
Independent Claim
133 words
A method for comparing two three-dimensional objects having similar shapes and dimensions which comprises: illuminating a side of one of the objects by a collimated light beam whose intensity is modulated in a direction transverse thereto at a spatial frequency of 1/p, said modulated light beam generating on the illuminated side of the object a lattice of alternately dark and light parallel bands similar to interference fringes having a configuration in the manner of contour lines determined by the relief of the illuminated side of the object and pitch p, similarly illuminating the other object but wherein the intensity modulation is phase-shifted by 180*, optically superimposing images of the illuminated sides of the two objects, and obtaining from the superimposed images the differential component thereof which is modulated at the spatial frequency 1/p.
Claim 4
Independent Claim
133 words
A method for comparing two three-dimensional objects having similar shapes and dimensions which comprises: illuminating a side of one of the objects by a collimated light beam whose intensity is modulated in a direction transverse thereto at a spatial frequency of 1/p, said modulated light beam generating on the illuminated side of the object a lattice of alternately dark and light parallel bands similar to interference fringes having a configuration in the manner of contour lines determined by the relief of the illuminated side of the object and pitch p, similarly illuminating the other object but wherein the intensity modulation is phase-shifted by 180*, optically superimposing images of the illuminated sides of the two objects, and obtaining from the superimposed images the differential component thereof which is modulated at the spatial frequency 1/p.
Claim 5
Dependent Claim
60 words
The method as defined in claim 1 for comparing two three-dimensional objects having similar shapes and dimensions wherein a single light beam is utilized which illuminates the two objects in succession and wherein the image of the first one of the objects to be illuminated is stored until the image of the second object to be illuminated has been obtained.
Claim 6
Dependent Claim
157 words
APparatus for comparing two three-dimensional objects having similar shapes and dimensions which comprises: means for illuminating a side of one of the objects by a collimated light beam whose intensity is modulated in a direction transverse thereto at a spatial frequency of 1/p, said modulated light beam generating on the illuminated side of the object a lattice of alternately dark and light parallel bands similar to interference fringes having a pitch p and a configuration in the manner of contour lines determined by the relief of the illuminated side of the object, means for similarly illuminating the same side of the other object and wherein the intensity modulation of the light beam in phase-shifted by 180*, means for superimposing images of the illuminated side of the two objects, means including a filter for obtaining from the superimposed images the differential component thereof which is modulated at the spatial frequency 1/p, and means for displaying said differential component.
Claim 7
Dependent Claim
157 words
APparatus for comparing two three-dimensional objects having similar shapes and dimensions which comprises: means for illuminating a side of one of the objects by a collimated light beam whose intensity is modulated in a direction transverse thereto at a spatial frequency of 1/p, said modulated light beam generating on the illuminated side of the object a lattice of alternately dark and light parallel bands similar to interference fringes having a pitch p and a configuration in the manner of contour lines determined by the relief of the illuminated side of the object, means for similarly illuminating the same side of the other object and wherein the intensity modulation of the light beam in phase-shifted by 180*, means for superimposing images of the illuminated side of the two objects, means including a filter for obtaining from the superimposed images the differential component thereof which is modulated at the spatial frequency 1/p, and means for displaying said differential component.
Claim 8
Dependent Claim
57 words
Apparatus as defined in claim 3 for comparing two three-dimensional objects having similar shapes and dimensions wherein said means for illuminating a side of the object comprises at least one source of a collimated light beam whose intensity is modulated along at least one direction transverse thereto and the phase of which can be shifted by 180*.
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) | 1978-04-21 | 1978-10-21 | 1979-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-21 | 1982-10-21 | 1983-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-21 | 1986-10-21 | 1987-04-22 | $7700.00 | Window Closed / Lapsed |