US3907439A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Edge-sensing with a scanning laser beam
Assignee: Zygo Corp
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Filing: 1974-04-24
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Granted: 1975-09-23
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Expires: 1994-04-24
Abstract
Abstract An electrooptical sensor is described which provides an output for precisely locating the edge of an object. By passing a collimated laser beam across the edge of an opaque object, either by moving the laser beam, by moving the object, or both, and photoelectrically sensing the light passing by the object, the coincidence of the edge of the object and the center of the laser beam can be precisely determined from the first and second derivatives of the output of a photodetector.
Inventors
- 👤 Carl A Zanoni
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 06:16
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/26; G01D5/32; G01D5/34; G01D5/342; G01B; G01B11/00; G01B11/02
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
161 words
An electrooptical edge-sensing device comprising (A) a source of radiant energy which produces a narrow beam; (B) means for scanning said beam and passing at least a portion thereof past an edge of an object; (C) means for collecting and photosensing said portion of said beam passing said edge to produce a first set of signals; (D) means to differentiate said first signals to produce a second signal with maximum intensity at points corresponding to said edge of said object; (E) means to further differentiate said second signal to produce a third signal of zero intensity at points corresponding to said edge of said object; (F) means to feed a portion of said second signal to a switch to which said third signal is also fed, which switch passes said third signal only for a limited period adjacent the peak of said second signal; and (G) means to utilize the signal from said switch in measuring the position of said edge.
Claim 2
Dependent Claim
161 words
An electrooptical edge-sensing device comprising (A) a source of radiant energy which produces a narrow beam; (B) means for scanning said beam and passing at least a portion thereof past an edge of an object; (C) means for collecting and photosensing said portion of said beam passing said edge to produce a first set of signals; (D) means to differentiate said first signals to produce a second signal with maximum intensity at points corresponding to said edge of said object; (E) means to further differentiate said second signal to produce a third signal of zero intensity at points corresponding to said edge of said object; (F) means to feed a portion of said second signal to a switch to which said third signal is also fed, which switch passes said third signal only for a limited period adjacent the peak of said second signal; and (G) means to utilize the signal from said switch in measuring the position of said edge.
Claim 3
Dependent Claim
14 words
The device of claim 1, in which the energy source is a gas laser.
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) | 1978-09-22 | 1979-03-24 | 1979-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-22 | 1983-03-24 | 1983-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-22 | 1987-03-24 | 1987-09-23 | $7700.00 | Window Closed / Lapsed |