Patent US4933541A successfully refreshed from Google Patents.
US4933541A
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Method and apparatus for active vision image enhancement with wavelength matching
Assignee: National Research Council Canada
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Filing: 1989-06-29
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Granted: 1990-06-12
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Expires: 2009-06-29
Abstract
Abstract A method and apparatus for optically inspecting the geometry of a surface in an environment which is subject to the presence of external light noise perturbations. A beam of monochromatic light having a predetermined wavelength and a structured light pattern is projected onto the surface to thereby scatter the structured light beam and produce a scattered light beam which is thereafter separated into first and second scattered beam portions. The first scattered beam portion is passed through a first optical filter having a narrow bandwidth and a central wavelength corresponding substantially to the wavelength of the projected light, thereby providing a first optical output signal representative of the surface geometry and of external light noise perturbation. The second scattered beam portion is passed through a second optical filter having a narrow wavelength bandwidth and a central wavelength which is closely spaced from the predetermined wavelength of the projected light by a wavelength offset such as to reject the projected light wavelength, thereby providing a second optical output signal representative of substantially the same external light noise perturbation as that passing through the first optical filter. The first and second optical output signals are detected and converted into first and second electrical signals, respectively. The second electrical signal is then subtracted from the first electrical signal to provide a substantially noise-free electrical output signal representative of the surface geometry. The invention is particularly useful for active vision robot welding and enables arc light noise-free images to be obtained in real time.
Inventors
- 👤 Marc Dufour
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 14:44
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/24; G01B11/25; G01B11/2509; B; B23; B23K; B23K9/00; B23K9/12; B23K9/127
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
225 words
A method of optically inspecting the geometry of a surface in an environment which is subject to the presence of external light noise perturbations, which comprises the steps of: (a) projecting a beam of monochromatic light having a predetermined wavelength and a structured light pattern onto said surface to thereby scatter the structured light beam and produce a scattered light beam; (b) separating said scattered light beam into first and second scattered beam portions; (c) passing said first scattered beam portion through a first optical filter having a narrow bandwidth and a central wavelength corresponding substantially to said predetermined wavelength, thereby providing a first optical output signal representative of the surface geometry and of external light noise perturbation; (d) passing said second scattered beam portion through a second optical filter having a narrow bandwidth and a central wavelength which is closely spaced from said predetermined wavelength by a wavelength offset such as to reject said predetermined wavelength, thereby providing a second optical output signal representative of substantially the same external light noise perturbation as that passing through said first optical filter; (e) detecting said first and second optical output signals and converting same into first and second electrical signals, respectively; and (f) subtracting said second electrical signal from said first electrical signal to provide a substantially noise-free electrical output signal representative of said surface geometry.
Claim 2
Independent Claim
225 words
A method of optically inspecting the geometry of a surface in an environment which is subject to the presence of external light noise perturbations, which comprises the steps of: (a) projecting a beam of monochromatic light having a predetermined wavelength and a structured light pattern onto said surface to thereby scatter the structured light beam and produce a scattered light beam; (b) separating said scattered light beam into first and second scattered beam portions; (c) passing said first scattered beam portion through a first optical filter having a narrow bandwidth and a central wavelength corresponding substantially to said predetermined wavelength, thereby providing a first optical output signal representative of the surface geometry and of external light noise perturbation; (d) passing said second scattered beam portion through a second optical filter having a narrow bandwidth and a central wavelength which is closely spaced from said predetermined wavelength by a wavelength offset such as to reject said predetermined wavelength, thereby providing a second optical output signal representative of substantially the same external light noise perturbation as that passing through said first optical filter; (e) detecting said first and second optical output signals and converting same into first and second electrical signals, respectively; and (f) subtracting said second electrical signal from said first electrical signal to provide a substantially noise-free electrical output signal representative of said surface geometry.
Claim 3
Dependent Claim
35 words
A method as claimed in claim 1, wherein step (a) is carried out by means of a laser diode optically coupled to an optical projection unit for projecting a structured laser beam onto said surface.
Claim 4
Dependent Claim
20 words
A method as claimed in claim 1, wherein step (b) is carried out by means of a 50%--50% beam splitter.
Claim 5
Dependent Claim
28 words
A method as claimed in claim 1, wherein said first and second optical filters comprise interference filters having a bandwidth ranging from about 2 to about 10 nanometers.
Claim 6
Dependent Claim
19 words
A method as claimed in claim 1, wherein said first and second optical filters have substantially the same bandwidth.
Claim 7
Dependent Claim
37 words
A method as claimed in claim 5, wherein said second optical filter has a central wavelength closely spaced from said predetermined wavelength by a wavelength offset which is substantially equal to the bandwidth of both said filters.
Claim 8
Dependent Claim
20 words
A method as claimed in claim 1, wherein step (e) is carried out by means of two separate CCD-type detectors.
Claim 9
Dependent Claim
28 words
A method as claimed in claim 7, wherein said first and second scattered beam portions are focussed through said first and second optical filters and onto said detectors.
Claim 10
Dependent Claim
39 words
A method as claimed in claim 7, wherein said first scattered beam portion is directed onto a mirror to produce a reflected beam portion which is thereafter directed through said first optical filter and onto one of said detectors.
Claim 11
Dependent Claim
24 words
A method as claimed in claim 7, wherein step (e) is carried out by means of an analog subtracting circuit connected to said detectors.
Claim 12
Independent Claim
270 words
An apparatus for optically inspecting the geometry of a surface in an environment which is subject to the presence of external light noise perturbations, which comprises: structured monochromatic light source means for generating a beam of monochromatic light having a predetermined wavelength with a structured light pattern and projecting same onto said surface to thereby scatter the structured light beam and produce a scattered light beam; beam splitting means for separating said scattered light beam into first and second scattered beam portions travelling along respective optical paths; a first optical filter having a narrow bandwidth and a central wavelength corresponding substantially to said predetermined wavelength, said first optical filter being arranged in the optical path of said first scattered beam portion to provide a first optical output signal representative of the surface geometry and of external light noise perturbation; a second optical filter having a narrow bandwidth and a central wavelength which is closely spaced from said predetermined wavelength by a wavelength offset such as to reject said predetermined wavelength, said second optical filter being arranged in the optical path of said second scattered beam portion to provide a second optical output signal representative of substantially the same external light noise perturbation as that passing through said first optical filter; first and second detector means for detecting said first and second optical output signals and converting same into first and second electrical signals, respectively; and a subtracting circuit connected to said first and second detector means for subtracting said second electrical signal from said first electrical signal to provide a substantially noise-free electrical output signal representative of said surface geometry.
Claim 13
Independent Claim
270 words
An apparatus for optically inspecting the geometry of a surface in an environment which is subject to the presence of external light noise perturbations, which comprises: structured monochromatic light source means for generating a beam of monochromatic light having a predetermined wavelength with a structured light pattern and projecting same onto said surface to thereby scatter the structured light beam and produce a scattered light beam; beam splitting means for separating said scattered light beam into first and second scattered beam portions travelling along respective optical paths; a first optical filter having a narrow bandwidth and a central wavelength corresponding substantially to said predetermined wavelength, said first optical filter being arranged in the optical path of said first scattered beam portion to provide a first optical output signal representative of the surface geometry and of external light noise perturbation; a second optical filter having a narrow bandwidth and a central wavelength which is closely spaced from said predetermined wavelength by a wavelength offset such as to reject said predetermined wavelength, said second optical filter being arranged in the optical path of said second scattered beam portion to provide a second optical output signal representative of substantially the same external light noise perturbation as that passing through said first optical filter; first and second detector means for detecting said first and second optical output signals and converting same into first and second electrical signals, respectively; and a subtracting circuit connected to said first and second detector means for subtracting said second electrical signal from said first electrical signal to provide a substantially noise-free electrical output signal representative of said surface geometry.
Claim 14
Dependent Claim
34 words
An apparatus as claimed in claim 11, wherein said structured monochromatic light source means comprises a laser diode optically coupled to an optical projection unit for projecting a structured laser beam onto said surface.
Claim 15
Dependent Claim
17 words
An apparatus as claimed in claim 11, wherein said beam splitting means comprises a 50%--50% beam splitter.
Claim 16
Dependent Claim
28 words
An apparatus as claimed in claim 11, wherein said first and second optical filters comprise interference filters having a bandwidth ranging from about 2 to about 10 nanometers.
Claim 17
Dependent Claim
19 words
An apparatus as claimed in claim 11, wherein said first and second optical filters have substantially the same bandwidth.
Claim 18
Dependent Claim
37 words
An apparatus as claimed in claim 15, wherein said second optical filter has a central wavelength closely spaced from said predetermined wavelength by a wavelength offset which is substantially equal to the bandwidth of both said filters.
Claim 19
Dependent Claim
36 words
An apparatus as claimed in claim 11, further including optical lens means for focussing said first and second scattered beam portions through said first and second optical filters and onto said first and second detector means.
Claim 20
Dependent Claim
50 words
An apparatus as claimed in claim 11, further including a mirror arranged in the optical path of said first scattered beam portion between said beam splitting means and said first optical filter for producing a reflected beam portion directed through said first optical filter and onto said first detector means.
Claim 21
Dependent Claim
19 words
An apparatus as claimed in claim 11, wherein said first and second detector means each comprise a CCD-type detector.
Claim 22
Dependent Claim
16 words
An apparatus as claimed in claim 11, wherein said subtracting circuit comprises an analog subtracting circuit.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-06-11 | 1993-12-11 | 1994-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-06-11 | 1997-12-11 | 1998-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-06-11 | 2001-12-11 | 2002-06-12 | $7700.00 | Window Closed / Lapsed |