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US3782827A
Expired / Lapsed
US
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Optical device for characterizing the surface or other properties of a sample
Assignee: Northrop Grumman Guidance and Electronics Co Inc
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Filing: 1971-08-04
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Granted: 1974-01-01
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Expires: 1991-08-04
Abstract
Abstract An optical device is disclosed which is useful for characterizing the surface topography of an opaque sample and for characterizing other properties of transparent samples. In the reflecting mode, a laser is used to illuminate the surface of a rotating sample. Reflected laser light is focused at a pinhole aperture where its intensity is detected. Useful plots of the power spectrum of the reflected coherent light as a function of frequency are obtained which characterize the surface topography of the sample. A transmitting embodiment of the device is also described wherein the transparent sample is mounted on the back side of a right-angle prism which has its hypotenuse side silvered. A laser beam enters the front side of the prism while the prism is rotated about the center of its hypotenuse. As in the reflecting mode, useful plots of the power spectrum of the transmitted, diffracted coherent light as a function of frequency are obtained which characterize properties of the sample. Processes for characterizing surface properties of opaque samples or other properties of transparent samples are also described.
Inventors
- 👤 P Nisenson
- 👤 E Blackman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 12:22
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/30; G01B11/303; G01N; G01N21/00; G01N21/84; G01N21/88; G01N21/89; G01N21/8901; G02; G02B; G02B27/00; G02B27/42; G02B27/46
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
64 words
An optical device for characterizing Properties of a sample through the use of the sample''s coherent power spectrum, comprising in combination: a. means to provide a beam of light which is at least partially coherent; b. means to direct said beam of light onto a portion of the sample; and, c. means to detect the coherent power spectrum of light modulated by said sample.
Claim 2
Dependent Claim
64 words
An optical device for characterizing Properties of a sample through the use of the sample''s coherent power spectrum, comprising in combination: a. means to provide a beam of light which is at least partially coherent; b. means to direct said beam of light onto a portion of the sample; and, c. means to detect the coherent power spectrum of light modulated by said sample.
Claim 3
Dependent Claim
25 words
An optical device of claim 1 wherein said means to provide comprises a source of light which is at least moderately temporally and spatially coherent.
Claim 4
Dependent Claim
14 words
An optical device of claim 2 wherein said means to provide comprises a laser.
Claim 5
Dependent Claim
27 words
An optical device of claim 3 wherein said means to detect includes means to rotate the sample around an axis through the plane of the sample''s surface.
Claim 6
Dependent Claim
43 words
An optical device of claim 4 wherein said means to detect further includes optical means to focus reflected light, a sampling aperture and a light intensity detector positioned to intercept the modulated focused light emitted from said sample in its back focal plane.
Claim 7
Dependent Claim
15 words
An optical device of claim 5 wherein said sample to be characterized is substantially opaque.
Claim 8
Dependent Claim
33 words
An optical device of Claim 6 wherein said means to direct includes a beam splitter positioned in the path of said coherent light beam and in the path of said reflected, modulated light.
Claim 9
Dependent Claim
15 words
An optical device of claim 7 wherein said light intensity detector contains a photomultiplier tube.
Claim 10
Dependent Claim
20 words
An optical device of claim 5 wherein the sample to be characterized is substantially transparent to said coherent light beam.
Claim 11
Dependent Claim
37 words
An optical device of claim 9 wherein said sample is mounted on one side of a right angle prism which has its hypotenuse silvered and said prism is mounted to rotate about the center of its hypotenuse.
Claim 12
Dependent Claim
18 words
An optical device of claim 10 wherein said coherent light beam enters the prism on its front face.
Claim 13
Dependent Claim
42 words
An optical device of claim 11 wherein said means to detect includes optical means to focus coherent light refracted through said sample and modulated by said sample and a light intensity detector positioned in the back focal plane of said modulated light.
Claim 14
Dependent Claim
31 words
An optical device of claim 12 wherein said light intensity detector comprises a photometer positioned on a horizontally translating member positioned at the back focal plane of said refracted, modulated light.
Claim 15
Independent Claim
40 words
A method for characterizing a rough surface on a sample, comprising: a. rotating said sample; b. illuminating the rough surface of said rotating sample with coherent light; c. sensing the coherent power spectrum of light reflected from said rough surface.
Claim 16
Independent Claim
40 words
A method for characterizing a rough surface on a sample, comprising: a. rotating said sample; b. illuminating the rough surface of said rotating sample with coherent light; c. sensing the coherent power spectrum of light reflected from said rough surface.
Claim 17
Dependent Claim
35 words
A method of claim 14 wherein step (c) is accomplished by: a. focusing said reflected light at a pinhole aperture; b. sensing the intensity of reflected light at a point immediately behind said pinhole aperture.
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) | 1976-12-31 | 1977-07-02 | 1978-01-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-31 | 1981-07-02 | 1982-01-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-31 | 1985-07-02 | 1986-01-01 | $7700.00 | Window Closed / Lapsed |