US3885875A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Noncontact surface profilometer
Assignee: Zygo Corp
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Filing: 1974-07-29
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Granted: 1975-05-27
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Expires: 1994-07-29
Abstract
Abstract An electrooptical sensor is described for providing an output proportional to the surface profile and the first derivative of the surface profile in a noncontacting manner. A narrow, collimated laser beam is scanned across the surface of the article to be measured. The scanning laser beam is produced with a uniformly rotating mirror and a lens, and the scanning beam is nominally perpendicular to the surface of the article being measured. The laser beam reflected by the surface is collected by a lens and focused onto a photoelectric position sensor. The output of the position sensor is proportional to the first derivative of the article surface profile. Since this first derivative will in general include a component originating from the tilt of the article surface relative to the scanning laser beam, means are provided for separating this effect from the intrinsic surface slope. By electronically integrating the first derivative output, an output representing the surface profile is obtained.
Inventors
- 👤 Alvin H Rosenfeld
- 👤 Carl A Zanoni
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 04:02
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/30; G01B11/303
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
214 words
A device for measuring the surface profile and the first derivative of the surface profile of a basically flat reflecting object (comprising) (1) a source of radiant energy, and means to produce a narrow collimated beam therefrom; (2) means for focusing said beam onto a uniformly rotating reflective surface tO produce a reflected beam on axis with; (3) means for recollimating said reflected beam to produce a linearly scanned beam which is scanned across the surface of said test object and reflected therefrom; (4) means for collecting said beam reflected from said test object and focusing it onto (5) a photoelectric position sensor; (6) means for processing the output of said position sensor to yield an output indicative of the first derivative of the surface profile of the test article along the line of intersection of said linearly scanned beam and the surface of the test object; (7) means for processing said first derivative output to produce an output indicative of the surface profile of the test article along said line of intersection and (8) means for processing the output of said position sensor in order to assure that said first derivative and surface profile outputs are independent of the tilt or alignment of the surface of the test article relative to the apparatus.
Claim 2
Independent Claim
214 words
A device for measuring the surface profile and the first derivative of the surface profile of a basically flat reflecting object (comprising) (1) a source of radiant energy, and means to produce a narrow collimated beam therefrom; (2) means for focusing said beam onto a uniformly rotating reflective surface tO produce a reflected beam on axis with; (3) means for recollimating said reflected beam to produce a linearly scanned beam which is scanned across the surface of said test object and reflected therefrom; (4) means for collecting said beam reflected from said test object and focusing it onto (5) a photoelectric position sensor; (6) means for processing the output of said position sensor to yield an output indicative of the first derivative of the surface profile of the test article along the line of intersection of said linearly scanned beam and the surface of the test object; (7) means for processing said first derivative output to produce an output indicative of the surface profile of the test article along said line of intersection and (8) means for processing the output of said position sensor in order to assure that said first derivative and surface profile outputs are independent of the tilt or alignment of the surface of the test article relative to the apparatus.
Claim 3
Dependent Claim
24 words
The device of claim 1, in which the source of energy is a gas laser which produces a narrow collimated beam of polarized light.
Claim 4
Dependent Claim
67 words
The device of claim 2, in which the means for collecting and focusing said beam reflected from said test object includes a lens, a retardation plate which passes said beam onto a polarization beam splitter in a single plane of polarization which is substantially totally reflected by said beam splitter, and a lens which focuses said beam reflected from said beam splitter onto said photoelectric position sensor.
Claim 5
Dependent Claim
137 words
The device of claim 1, in which the means for processing the output of said position sensor to assure independence of the alignment of said surface of said test object comprises a switch which (1) on a first scan feeds the output indicative of the first derivative of the surface profile of the test object to an integrator whose output provides the average slope over the said scan, the said integrator output being fed to a sample-and-hold device and thence to differencing circuitry, and (2) on the next scan feeds said output indicative of the first derivative of the surface profile of the test object directly into said differencing circuitry, which thereby provides an output which is proportional to the first derivative of the surface profile of said test object independent of the alignment of its surface.
References Cited (Backward Citations)
US3679307A
Cited
US3761179A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-26 | 1978-11-25 | 1979-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-26 | 1982-11-25 | 1983-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-26 | 1986-11-25 | 1987-05-27 | $7700.00 | Window Closed / Lapsed |