US5298976A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for measuring surface distances from a reference plane
Assignee: Individual
•
Filing: 1992-11-16
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Granted: 1994-03-29
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Expires: 2012-11-16
Abstract
Abstract A method of measuring the distance of an examined surface from a reference plane, by: (a) directing a parallel beam of radiation along a first optical path in which the parallel beam is focussed as a spot on the examined surface and reflected therefrom; (b) converting the reflected beam to a parallel beam; (c) directing a part of the reflected parallel beam through a second optical path in which the spot is focussed on a surface of a first detector located such that the position of the spot on the first detector includes both drawback errors caused by variations in reflectivity, scattering, and/or interference in the examined surface; and a plane displacement error, representing the distance between the plane of the examined surface and the reference plane; (d) directing another part of the reflected parallel beam through a third optical path in which the spot is focussed on a surface of a second detector located such that the position of the spot on the second detector includes only the drawback errors; (e) and utilizing the outputs of the first and second detectors for providing a measurement of the distance of the examined surface from the reference plane.
Inventors
- 👤 Arie Shahar
- 👤 Nira Schwartz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 18:12
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70483; G03F7/70605; G03F7/70616; G01; G01B; G01B11/00; G01B11/02; G01B11/026; G03F9/00; G03F9/70
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
216 words
A method of measuring the distance of an examined surface from a reference plane, comprising the steps: (a) directing a parallel beam of radiation along a first optical path which includes first focussing means for focussing the parallel beam as a spot on the examined surface and reflecting it therefrom as a reflected beam; (b) converting the reflected beam to a parallel beam; (c) directing a part of the reflected parallel beam through a second optical path which includes second focussing means for focussing the spot on a surface of a first detector located such that the position of the spot on the first detector includes both: (i) drawback errors caused by variations in reflectivity, scattering, and/or interference in the examined surface; and (ii) a plane displacement error, representing the distance between the plane of the examined surface and the reference plane; (d) directing another part of the reflected parallel beam through a third optical path which includes third focussing means for focussing the spot on a surface of a second detector located such that the position of the spot on the second detector includes only said drawback errors (i); (e) and utilizing the outputs of said first and second detectors for providing a measurement of the distance of the examined surface from the reference plane.
Claim 2
Independent Claim
216 words
A method of measuring the distance of an examined surface from a reference plane, comprising the steps: (a) directing a parallel beam of radiation along a first optical path which includes first focussing means for focussing the parallel beam as a spot on the examined surface and reflecting it therefrom as a reflected beam; (b) converting the reflected beam to a parallel beam; (c) directing a part of the reflected parallel beam through a second optical path which includes second focussing means for focussing the spot on a surface of a first detector located such that the position of the spot on the first detector includes both: (i) drawback errors caused by variations in reflectivity, scattering, and/or interference in the examined surface; and (ii) a plane displacement error, representing the distance between the plane of the examined surface and the reference plane; (d) directing another part of the reflected parallel beam through a third optical path which includes third focussing means for focussing the spot on a surface of a second detector located such that the position of the spot on the second detector includes only said drawback errors (i); (e) and utilizing the outputs of said first and second detectors for providing a measurement of the distance of the examined surface from the reference plane.
Claim 3
Dependent Claim
68 words
The method according to claim 1, wherein the magnification in said second optical path is different from that in said third optical path; said step (e) including adjusting the drawback errors (i) detected by the second detector in step (e) by the ratio between the two magnifications in utilizing the outputs of the first and second detectors for providing a measurement of said plane displacement error (ii) alone.
Claim 4
Dependent Claim
24 words
The method according to claim 1, wherein said surface of the first detector is coplanar with a virtual axis of said first focussing means.
Claim 5
Dependent Claim
24 words
The method according to claim 1, wherein said surface of the second detector is perpendicular to a virtual axis of said first focussing means.
Claim 6
Dependent Claim
55 words
The method according to claim 4, wherein said third optical path includes a first focussing lens focussing the spot on the optical axis of a second focussing lens which in turn focusses the spot on the optical axis of a third focussing lens whose optical axis is perpendicular to said surface of the second detector.
Claim 7
Dependent Claim
23 words
The method according to claim 1, wherein said third optical path is a straight path separate and distinct from said second optical path.
Claim 8
Dependent Claim
42 words
The method according to claim 1, wherein the part of the parallel beam in said third optical path is reflected back towards said first optical path and is focussed on said spot of the examined surface and then on said second detector.
Claim 9
Dependent Claim
45 words
The method according to claim 7, wherein one of said detectors is a CCD camera and includes image processing means which processes the output of the camera to determine from the image focussed thereon the drawback errors corresponding to those detected by the first detector.
Claim 10
Dependent Claim
20 words
The method according to claim 8, wherein said second detector is the CCD camera and includes said image processing means.
Claim 11
Dependent Claim
35 words
The method according to claim 1, wherein said first optical path includes a variable intensity filter which is controlled by the output of at least one of said detectors to maintain a constant beam intensity.
Claim 12
Dependent Claim
230 words
Apparatus for measuring the distance of an examined surface from a reference plane, comprising: (a) a first detector; (b) a second detector; (c) means for directing a parallel beam of radiation along a first optical path which includes first focussing means for focussing the parallel beam as a spot on the examined surface and reflecting it therefrom as a reflected beam; (d) means for converting the reflected beam to a parallel beam; (e) means for directing a part of the reflected parallel beam through a second optical path which includes second focussing means for focussing the spot on a surface of said first detector located such that the position of the spot on the first detector includes both: (i) drawback errors caused by variations in reflectivity, scattering, and/or interference in the examined surface; and (ii) a plane displacement error, representing the distance between the plane of the examined surface and the reference plane; (f) means for directing another part of the reflected parallel beam through a third optical path including third focussing means for focussing the spot on a surface of said second detector located such that the position of the spot on the second detector includes only said drawback errors (i); (g) and means for utilizing the outputs of said first and second detectors for providing a measurement of the distance of the examined surface from the reference plane.
Claim 13
Dependent Claim
230 words
Apparatus for measuring the distance of an examined surface from a reference plane, comprising: (a) a first detector; (b) a second detector; (c) means for directing a parallel beam of radiation along a first optical path which includes first focussing means for focussing the parallel beam as a spot on the examined surface and reflecting it therefrom as a reflected beam; (d) means for converting the reflected beam to a parallel beam; (e) means for directing a part of the reflected parallel beam through a second optical path which includes second focussing means for focussing the spot on a surface of said first detector located such that the position of the spot on the first detector includes both: (i) drawback errors caused by variations in reflectivity, scattering, and/or interference in the examined surface; and (ii) a plane displacement error, representing the distance between the plane of the examined surface and the reference plane; (f) means for directing another part of the reflected parallel beam through a third optical path including third focussing means for focussing the spot on a surface of said second detector located such that the position of the spot on the second detector includes only said drawback errors (i); (g) and means for utilizing the outputs of said first and second detectors for providing a measurement of the distance of the examined surface from the reference plane.
Claim 14
Dependent Claim
67 words
The apparatus according to claim 11, wherein the magnification in said second optical path is different from that in said third optical path; said means (g) including means for adjusting the drawback errors (i) detected by the second detector by the ratio between the two magnifications in utilizing the outputs of the first and second detectors for providing a measurement of said plane displacement error (ii) alone.
Claim 15
Dependent Claim
24 words
The apparatus according to claim 11, wherein said surface of the first detector is coplanar with a virtual axis of said first focussing means.
Claim 16
Dependent Claim
24 words
The apparatus according to claim 11, wherein said surface of the second detector is perpendicular to a virtual axis of said first focussing means.
Claim 17
Dependent Claim
55 words
The apparatus according to claim 14, wherein said third optical path includes a first focussing lens focussing the spot on the optical axis of a second focussing lens which in turn focusses the spot on the optical axis of a third focussing lens whose optical axis is perpendicular to said surface of the second detector.
Claim 18
Dependent Claim
23 words
The apparatus according to claim 11, wherein said third optical path is a straight path separate and distinct from said second optical path.
Claim 19
Dependent Claim
50 words
The apparatus according to claim 11, wherein said third optical path includes a retro-reflector which reflects said parallel beam in said path back towards said first optical path, and focussing means which focusses said reflected back beam on said spot of the examined surface and then on said second detector.
Claim 20
Dependent Claim
45 words
The apparatus according to claim 17, wherein one of said detectors is a CCD camera and includes image processing means which processes the output of the camera to determine from the image focussed thereon the drawback errors corresponding to those detected by the first detector.
Claim 21
Dependent Claim
20 words
The apparatus according to claim 18, wherein said second detector is the CCD camera and includes said image processing means.
Claim 22
Dependent Claim
44 words
The apparatus according to claim 11, wherein said first optical path includes a variable intensity filter, said apparatus further including control means for controlling said filter in accordance with the output of at least one of said detectors to maintain a constant beam intensity.
References Cited (Backward Citations)
US4356392A
Cited
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1997-03-28 | 1997-09-27 | 1998-03-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-03-28 | 2001-09-27 | 2002-03-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-03-28 | 2005-09-27 | 2006-03-29 | $7700.00 | Window Closed / Lapsed |