US3900265A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Laser scanner flaw detection system
Assignee: Intec Corp
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Filing: 1974-03-08
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Granted: 1975-08-19
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Expires: 1994-03-08
Abstract
Abstract A laser scanner flaw detection system is provided with improved optics in the scanner and receiver for imaging the laser beam on a detector from the material being examined. A center-to-side scanning pattern is illustrated to provide complete scanning of the material as well as simplifying the provision of accurate scan position information. The system includes circuitry for preventing errors in quantizing flaws because of scanning velocity changes and flaw amplitude fluctuations on subsequent scans of the same flaw.
Inventors
- 👤 Monty M Merlen
- 👤 Peter H Nichols
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 12:32
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/84; G01N21/88; G01N21/89
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
276 words
A laser scanner flaw detection system for detecting flaws on a surface of material, comprising a. a laser for emitting a laser beam of radiation, b. scanner means for successively scanning said laser beam across a surface of material being examined, c. receiver means having a field of view and a detector means for receiving radiation applied by said laser beam from said surface to said detector means producing, signals therefrom in response to the radiation applied to said detector means, d. flaw amplitude discriminator means coupled to said detector means for producing flaw signals therefrom when the signals from said detector means exceed a predetermined level, e. laser beam position indicating means for producing beam position signals, f. variable flaw gate control means having said beam position signals coupled thereto for providing variable flaw gate control signals which vary in accordance with the scan position of said laser beam, g. one-scan delay variable width flaw gate means having said flaw signals from said discriminator and said flaw gate control signals coupled thereto for providing a one-scan delay variable time width flaw gate signals which vary in accordance with the scan position of said laser beam, and h. flaw quantizer means coupled to said flaw amplitude discriminator and said one-scan delay variable width flaw gate means for passing an output indicative of a flaw on the surface of the material being examined only on the first occurrence of a flaw signal during an active scan interval, and inhibiting subsequent flaws signals occurring during adjacent successive scans which occur during the time intervals of the flaw gates established by said one-scan delay variable width flaw gate means.
Claim 2
Dependent Claim
276 words
A laser scanner flaw detection system for detecting flaws on a surface of material, comprising a. a laser for emitting a laser beam of radiation, b. scanner means for successively scanning said laser beam across a surface of material being examined, c. receiver means having a field of view and a detector means for receiving radiation applied by said laser beam from said surface to said detector means producing, signals therefrom in response to the radiation applied to said detector means, d. flaw amplitude discriminator means coupled to said detector means for producing flaw signals therefrom when the signals from said detector means exceed a predetermined level, e. laser beam position indicating means for producing beam position signals, f. variable flaw gate control means having said beam position signals coupled thereto for providing variable flaw gate control signals which vary in accordance with the scan position of said laser beam, g. one-scan delay variable width flaw gate means having said flaw signals from said discriminator and said flaw gate control signals coupled thereto for providing a one-scan delay variable time width flaw gate signals which vary in accordance with the scan position of said laser beam, and h. flaw quantizer means coupled to said flaw amplitude discriminator and said one-scan delay variable width flaw gate means for passing an output indicative of a flaw on the surface of the material being examined only on the first occurrence of a flaw signal during an active scan interval, and inhibiting subsequent flaws signals occurring during adjacent successive scans which occur during the time intervals of the flaw gates established by said one-scan delay variable width flaw gate means.
Claim 3
Dependent Claim
61 words
The laser scanner flaw detection system set forth in claim 1 wherein said flaw quantizer means includes a multiple line scan memory delay means for inhibiting any output from flaw signals produced by the flaws which occur during a given flaw gate until the flaw signal which produced such flaw gate disappears for a predetermined number of subsequent multiple line scans.
Claim 4
Dependent Claim
59 words
The laser scanner flaw detection system set forth in claim 2 wherein said multiple line scan memory delay means provides variable time width flaw gate signals with feedback means coupling said multiple line scan memory delay means to said flaw amplitude discriminator means for lowering said predetermined level during the occurrence of said variable time width flaw gate signals.
Claim 5
Dependent Claim
50 words
The structure set forth in claim 1 having feedback means coupled between said flaw quantizer and said discriminator means for feeding back said one-scan delay variable time width flaw gate signals to said discriminator which lowers the said predetermined level of said discriminator when said flaw gate signals are present.
Claim 6
Dependent Claim
64 words
The laser scanner flaw detection system set forth in claim 1 wherein said laser beam has a center position on the surface of material being scanned by said scanner means, said laser beam position means comprising a center pickup assembly for generating a center pickup signal when said laser beam crosses the center position of its scan across the surface of material being examined.
Claim 7
Dependent Claim
89 words
The structure set forth in claim 5 wherein said center pickup assembly comprises a partially reflective window in the path of said laser beam, a focusing lens, an opaque mask with an opening therein aligned with the center position of the laser beam during the scanning thereof, and detector means, said focusing lens imaging the center position of said laser beam reflected from said window onto said mask opening with light therefrom being applied to said detector means for producing a center pickup signal output from said detector means.
Claim 8
Dependent Claim
47 words
The structure set forth in claim 1 wherein said variable flaw gate control means includes active scan defining means for producing active scan position signals only when the laser beam is moving from center either side across the surface of material being examined on each scan interval.
Claim 9
Dependent Claim
130 words
The structure set forth in claim 1 wherein said scanner means includes a. a galvanometer mirror driven by a high speed galvanometer for scanning said laser beam across the surface of the material being examined, b. a pair of cylindrical focusing lenses with their optical axes being orthogonal to each other for adjusting the spot size on the material surface from said laser beam in width and length parallel to and perpendicular to the direction of scan of said laser beam, and c. a spherical lens positioned between said galvanometer mirror and said pair of cylindrical lenses at a distance from said galvanometer mirror equal to its focal length for imaging light passing through said cylindrical focusing lenses via said galvanometer mirror onto the surface of the material being examined.
Claim 10
Dependent Claim
85 words
The structure set forth in claim 1 wherein said detector means comprises a photomultiplier tube having a face thereon and said receiver means includes receiver optical means for collecting light from the scanning laser beam spot on said surface of material and spreading said light across the face of said photomultiplier tube for eliminating changes of flaw signal amplitude due to differences in sensitivity across the face of said photomultiplier tube and changes of angles between the scanning laser beam, material surface, and photomultiplier tube.
Claim 11
Dependent Claim
180 words
The structures set forth in claim 9 wherein said receiver optical means comprises a. a combination of lenses having a pair of back-to-back Fresnel lenses and a first cylindrical lens, said combination of lenses having different focal lengths with respect to axes perpendicular and parallel to a scan line scanned by said laser beam on said surface of material being examined, and b. a second cylindrical lens having a mask with an opening therein for determining the receiver field of view in a direction perpendicular to said scan line, c. said combination of lenses being positioned in a plane with respect to said scanning means, said photomultiplier tube, and said scan line, such that said scanning means is imaged on said photomultiplier tube, and d. said second cylindrical lens being positioned with respect to said combination of lenses and said photomultiplier tube for imaging said combination of lenses on said photomultiplier tube in a direction perpendicular to said scan line, said combination of lenses imaging said scan line onto said opening in said opaque mask of said seconD cylindrical lens.
Claim 12
Dependent Claim
42 words
The structure set forth in claim 10 wherein the distances from said scanning means to said scan line and from said scan line to said receiver remain the same, with said receiver means and said scanner means being located in different planes.
Claim 13
Dependent Claim
235 words
A laser scanner flaw detection system for detecting flaws on a surface of material comprising a. a laser for emitting a laser beam of radiation, b. scanner means for successively scanning said laser beam across the surface of material being examined, said laser beam having a predetermined scan path including a center position on said surface of material, c. center position means for generating a center position signal whenever said scanning laser beam is at said center position on the surface of material being examined, d. active scan position indicator means having said center position signal coupled thereto for producing an active scan output signal only during scanning intervals of the laser beam from center to side in either direction on the material being examined, e. receiver means having a detector means for receiving radiation applied by said laser beam from said surface to said detector means producing a flaw signal therefrom in response to the radiation applied to said detector means, f. flaw amplitude discriminator means coupled to said detector means for producing flaw signal outputs therefrom when the flaw signals from said detector means exceed a predetermined level, and g. gating means having inputs from said flaw amplitude discriminator means and said active scan position indicator means coupled thereto for passing flaw signals of predetermined amplitude only during active scan intervals from center to side on each scan of the material being examined.
Claim 14
Dependent Claim
235 words
A laser scanner flaw detection system for detecting flaws on a surface of material comprising a. a laser for emitting a laser beam of radiation, b. scanner means for successively scanning said laser beam across the surface of material being examined, said laser beam having a predetermined scan path including a center position on said surface of material, c. center position means for generating a center position signal whenever said scanning laser beam is at said center position on the surface of material being examined, d. active scan position indicator means having said center position signal coupled thereto for producing an active scan output signal only during scanning intervals of the laser beam from center to side in either direction on the material being examined, e. receiver means having a detector means for receiving radiation applied by said laser beam from said surface to said detector means producing a flaw signal therefrom in response to the radiation applied to said detector means, f. flaw amplitude discriminator means coupled to said detector means for producing flaw signal outputs therefrom when the flaw signals from said detector means exceed a predetermined level, and g. gating means having inputs from said flaw amplitude discriminator means and said active scan position indicator means coupled thereto for passing flaw signals of predetermined amplitude only during active scan intervals from center to side on each scan of the material being examined.
Claim 15
Dependent Claim
91 words
The structure set forth in claim 12 wherein said center position means comprises a partially reflective window positioned in the scan path of said laser beam, a focusing lens, an opaque mask with an opening therein aligned with said center position of the laser beam during the scanning thereof and detector means, said focusing lens imaging said center position of said laser beam reflected from said window onto said mask opening with light therefrom being applied to said detector means for producing a center pickup signal output from said detector means.
Claim 16
Dependent Claim
205 words
A laser scanner flaw detection system for detecting flaws on a surface of material, comprising a. a laser for emitting a laser beam of radiation having a spot size, b. scanner means for successively scanning said laser beam across a surface of material being examined, c. said scanner means including a pair of cylindrical focusing lenses with their cylindrical axes being orthogonal to each other for adjusting said spot size on the material surface from said laser beam in width and length parallel and perpendicular to the direction of scan of said laser beam, and a spherical lens positioned between said scanning means and said pair of cylindrical lenses at a distance from said scanning means equal to its focal length for imaging laser light passing through said cylindrical focusing lenses via said scanning means onto the surface of the material being examined, d. receiver means having a detector means for receiving radiation applied by said laser beam from said surface to said detector means producing signals therefrom in response to the radiation applied to said detector means, and e. flaw amplitude discriminator means coupled to said detector means for producing flaw output signals when said signals from said detector means exceed a predetermined level.
Claim 17
Dependent Claim
205 words
A laser scanner flaw detection system for detecting flaws on a surface of material, comprising a. a laser for emitting a laser beam of radiation having a spot size, b. scanner means for successively scanning said laser beam across a surface of material being examined, c. said scanner means including a pair of cylindrical focusing lenses with their cylindrical axes being orthogonal to each other for adjusting said spot size on the material surface from said laser beam in width and length parallel and perpendicular to the direction of scan of said laser beam, and a spherical lens positioned between said scanning means and said pair of cylindrical lenses at a distance from said scanning means equal to its focal length for imaging laser light passing through said cylindrical focusing lenses via said scanning means onto the surface of the material being examined, d. receiver means having a detector means for receiving radiation applied by said laser beam from said surface to said detector means producing signals therefrom in response to the radiation applied to said detector means, and e. flaw amplitude discriminator means coupled to said detector means for producing flaw output signals when said signals from said detector means exceed a predetermined level.
Claim 18
Dependent Claim
83 words
The structure set forth in claim 14 wherein said detector means comprises a photomultiplier tube having a face thereon and said receiver means includes receiver optical means for collecting light from said laser beam on said surface of material and spreading said light across said face of said photomultiplier tube for eliminating changes of flaw signAl amplitude due to differences in sensitivity across the face of said photomultiplier tube and changes of angles between the scanning laser beam, material surface, and photomultiplier tube.
Claim 19
Dependent Claim
275 words
A laser scanner flaw detection system for detecting flaws on a surface of material, comprising a. a laser for emitting a laser beam of radiation, b. scanner means for successively scanning said laser beam across a surface of material being examined, c. receiver means having a field of view, receiver optical means, and a detector means for receiving radiation applied from said surface to said detector means producing signals therefrom in response to the radiation applied thereto, d. said receiver optical means comprising a combination of lenses having a pair of back-to-back Fresnel lenses and a first cylindrical lens, said combination of lenses having different focal lengths with respect to axes perpendicular and parallel to a scan line scanned by said laser beam on said surface of material being examined, and a second cylindrical lens having a mask with an opening therein for determining the receiver field of view in a direction perpendicular to said scan line, e. said combination of lenses being positioned in a plane with respect to said scanning means, said detector means and said scan line such that said scanning means is imaged on said detector means, f. said second cylindrical lens being positioned with respect to said combination of lenses and said detector means for imaging said combination of lenses on said detector means in a direction perpendicular to said scan line, said combination of lenses imaging said scan line onto said opening in said opaque mask of said second cylindrical lens, and g. flaw amplitude discriminator means coupled to said detector means for producing flaw signal outputs therefrom when said signals from said detector means exceed a predetermined level.
Claim 20
Dependent Claim
275 words
A laser scanner flaw detection system for detecting flaws on a surface of material, comprising a. a laser for emitting a laser beam of radiation, b. scanner means for successively scanning said laser beam across a surface of material being examined, c. receiver means having a field of view, receiver optical means, and a detector means for receiving radiation applied from said surface to said detector means producing signals therefrom in response to the radiation applied thereto, d. said receiver optical means comprising a combination of lenses having a pair of back-to-back Fresnel lenses and a first cylindrical lens, said combination of lenses having different focal lengths with respect to axes perpendicular and parallel to a scan line scanned by said laser beam on said surface of material being examined, and a second cylindrical lens having a mask with an opening therein for determining the receiver field of view in a direction perpendicular to said scan line, e. said combination of lenses being positioned in a plane with respect to said scanning means, said detector means and said scan line such that said scanning means is imaged on said detector means, f. said second cylindrical lens being positioned with respect to said combination of lenses and said detector means for imaging said combination of lenses on said detector means in a direction perpendicular to said scan line, said combination of lenses imaging said scan line onto said opening in said opaque mask of said second cylindrical lens, and g. flaw amplitude discriminator means coupled to said detector means for producing flaw signal outputs therefrom when said signals from said detector means exceed a predetermined level.
Claim 21
Dependent Claim
42 words
The structure set forth in claim 16 wherein the distances from said scanning means to said scan line and from said scan line to said receiver remain the same, with said receiver means and said scanning means being located in different planes.
Claim 22
Dependent Claim
50 words
The structure set forth in claim 16 wherein said receiver optical means includes a lamp and a fold-down mirror when in fold-down position images said lamp through said receiver optical means for showing the surface of material being scanned from which light will produce output signals from said detector means.
Claim 23
Dependent Claim
205 words
A laser scanner flaw detection system for detecting flaws on a surface of material, comprising a. a laser for emitting a laser beam of radiation, b. scanner means for successively scanning said laser beam across a surface of material being examined, c. receiver means having a detector means for receiving radiation applied by said laser beam from said surface to said detector means producing signals therefrom in response to the radiation applied to said detector means, d. flaw amplitude discriminator means coupled to said detector means for producing a flaw output signal indicative of a flaw occurring on the surface of material being examined when said signals from said detector means exceed a predetermined level, e. one-scan delay flaw gate means for generating flaw gate signals which surround said flaw output signal on the next scan line, and f. multiple line scan memory flaw quantizer means having said flaw gate signals coupled thereto and having an input connected to the output of said flaw amplitude discriminator means for producing an output indicative of a flaw only on the first occurrence during a scan interval and preventing an output for a flaw located in the same position during a predetermined number of subsequent multiple line scans.
Claim 24
Dependent Claim
205 words
A laser scanner flaw detection system for detecting flaws on a surface of material, comprising a. a laser for emitting a laser beam of radiation, b. scanner means for successively scanning said laser beam across a surface of material being examined, c. receiver means having a detector means for receiving radiation applied by said laser beam from said surface to said detector means producing signals therefrom in response to the radiation applied to said detector means, d. flaw amplitude discriminator means coupled to said detector means for producing a flaw output signal indicative of a flaw occurring on the surface of material being examined when said signals from said detector means exceed a predetermined level, e. one-scan delay flaw gate means for generating flaw gate signals which surround said flaw output signal on the next scan line, and f. multiple line scan memory flaw quantizer means having said flaw gate signals coupled thereto and having an input connected to the output of said flaw amplitude discriminator means for producing an output indicative of a flaw only on the first occurrence during a scan interval and preventing an output for a flaw located in the same position during a predetermined number of subsequent multiple line scans.
Claim 25
Dependent Claim
91 words
The structure set forth in claim 19 including feedback means coupled between said multiple line scan memory flaw quantizer means and said flaw amplitude discriminator for dropping the predetermined level of saiD flaw amplitude discriminator for a predetermined number of subsequent multiple line scans after a flaw signal is passed, thereby to insure that the same flaw represented by said flaw signal disappears for a predetermined number of multiple line scans before a new flaw which occurs at the same position on said surface of material is passed by said quantizer.
Claim 26
Dependent Claim
262 words
A laser scanner flaw detection system for detecting flaws on a surface of material, comprising a. a laser for emitting a laser beam of radiation, b. scanner means for successively scanning said laser beam across a surface of material being examined, forming a plurality of successive scan lines thereon, c. receiver means having a detector means for receiving radiation applied by said laser beam from said surface to said detector means producing a flaw signal therefrom in response to the intensity of radiation applied to said detector means, d. flaw amplitude discriminator means coupled to said detector means for producing a flaw output signal indicative of a flaw occurring at a position along one of said scan lines when the flaw signals from said detector means exceed a predetermined level, e. one-scan delay flaw gate means for generating flaw gate signals which surround said flaw on the next scan line, f. flaw quantizer means having the output of said flaw amplitude discriminator means and said flaw gate signals coupled thereto for producing an output indicative of said flaw during said one of said scan lines and preventing an output for said flaw located in the same position during a subsequent scan line, and g. feedback means coupling said flaw gate signals from said flaw quantizer means to said amplitude discriminator means for dropping said predetermined level of said flaw amplitude discriminator for at least a subsequent scan line to insure said flaw disappears for at least one scan line before a new flaw is passed in the same position by said quantizer.
Claim 27
Dependent Claim
262 words
A laser scanner flaw detection system for detecting flaws on a surface of material, comprising a. a laser for emitting a laser beam of radiation, b. scanner means for successively scanning said laser beam across a surface of material being examined, forming a plurality of successive scan lines thereon, c. receiver means having a detector means for receiving radiation applied by said laser beam from said surface to said detector means producing a flaw signal therefrom in response to the intensity of radiation applied to said detector means, d. flaw amplitude discriminator means coupled to said detector means for producing a flaw output signal indicative of a flaw occurring at a position along one of said scan lines when the flaw signals from said detector means exceed a predetermined level, e. one-scan delay flaw gate means for generating flaw gate signals which surround said flaw on the next scan line, f. flaw quantizer means having the output of said flaw amplitude discriminator means and said flaw gate signals coupled thereto for producing an output indicative of said flaw during said one of said scan lines and preventing an output for said flaw located in the same position during a subsequent scan line, and g. feedback means coupling said flaw gate signals from said flaw quantizer means to said amplitude discriminator means for dropping said predetermined level of said flaw amplitude discriminator for at least a subsequent scan line to insure said flaw disappears for at least one scan line before a new flaw is passed in the same position by said quantizer.
References Cited (Backward Citations)
US3781531A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-18 | 1979-02-17 | 1979-08-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-18 | 1983-02-17 | 1983-08-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-18 | 1987-02-17 | 1987-08-19 | $7700.00 | Window Closed / Lapsed |