US3781531A
Expired / Lapsed
US
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Flaw detector system utilizing a laser scanner
Assignee: Union Trust Co
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Filing: 1972-06-23
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Granted: 1973-12-25
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Expires: 1992-06-23
Abstract
Abstract A laser beam is scanned successively across a surface of material being analyzed, and the intensity of the beam, either reflected or transmitted from the material, is detected by a photomultiplier tube. In addition to output amplitude, variations due to scanning across material flaws, other photomultiplier output variations also occur. Such baseline variations are due to relative angle changes that occur between the laser beam and the material surface and other system-associated errors. The same optical and/or electrical variations that produce these baseline signals also cause corresponding amplitude variations of detected flaw signals. A flaw amplitude normalizer circuit is coupled to the detector for automatically normalizing the flaw signal to remove these errors by providing high and low-pass filters to separate the flaw signal from the baseline scanning signal, and these signals are ratioed to develop a normalized flaw signal. A threshold circuit is coupled to the flaw amplitude normalizer circuit for producing flaw output signals when the normalized flaw signals from the detector exceed a predetermined level. Outputs from the threshold circuit are applied to a flaw quantizer circuit which, using ''''0-1'''' logic to indicate a flaw area and discriminate against the same indication on successive scans which occur at the same position in the scan as the initial flaw indication, thus provides a single flaw indication for the same flaw, although it may occur on successive scans.
Inventors
- 👤 C Baker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:25
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/84; G01N21/88; G01N21/89
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
175 words
A flaw detection system utilizing a laser scanner for detecting flaws on a surface of material, comprising a. a laser for emitting a beam of radiation, b. means for successively scanning said laser beam across a surface of material being analyzed, c. detector means for receiving radiation applied by said laser beam from said surface producing a signal in response to the intensity of the radiation applied to said detector means, d. flaw amplitude normalizer means coupled to said detector for automatically normalizing flaw signal amplitudes which vary due to scanning and changes in the electrical characteristics of the system comprsing a high-pass filter for passing flaw signals from said detector means, a low-pass filter for passing scan baseline signals from said detector means, and means for ratioing said flaw signals with said baseline signals to normalize said flaw signals along the length of the scan line, and e. threshold circuit coupled to said flaw amplitude normalizer means for producing a flaw output signal when the signals from said detector means exceed a predetermined level.
Claim 2
Dependent Claim
175 words
A flaw detection system utilizing a laser scanner for detecting flaws on a surface of material, comprising a. a laser for emitting a beam of radiation, b. means for successively scanning said laser beam across a surface of material being analyzed, c. detector means for receiving radiation applied by said laser beam from said surface producing a signal in response to the intensity of the radiation applied to said detector means, d. flaw amplitude normalizer means coupled to said detector for automatically normalizing flaw signal amplitudes which vary due to scanning and changes in the electrical characteristics of the system comprsing a high-pass filter for passing flaw signals from said detector means, a low-pass filter for passing scan baseline signals from said detector means, and means for ratioing said flaw signals with said baseline signals to normalize said flaw signals along the length of the scan line, and e. threshold circuit coupled to said flaw amplitude normalizer means for producing a flaw output signal when the signals from said detector means exceed a predetermined level.
Claim 3
Dependent Claim
62 words
The flaw detection system set forth in claim 1 wherein said means for ratioing said flaw signals with said baseline signals comprises an analog multiplier circuit coupled to said low-pass filter, an operational amplifier coupled to said high-pass filter and said analog multiplier circuit, and means for coupling the output of said operational amplifier to the input of said analog multiplier circuit.
Claim 4
Dependent Claim
68 words
The flaw detection system set forth in claim 1 wherein said means for ratioing said flaw signals with said baseline signals comprise an analog multiplex circuit coupled to said high-pass filter, means coupled between said low-pass filter and said analog multiplier circuit for applying the reciprocal of said scan baseline signals to said analog multiplier circuit whereby the output of said analog multiplier circuit provides normalized flaw signals.
Claim 5
Dependent Claim
55 words
The flaw detection system of claim 1 including a flaw quantizer circuit coupled to said threshold circuit for passing an output indicative of a flaw only on the first occurrence of a flaw signal during a scan interval, and rejecting subsequent flaw signals during adjacent successive scan intervals which occur at the same scan position.
Claim 6
Dependent Claim
118 words
The flaw detection system of claim 4 wherein said flaw quantizer circuit comprises a. an adjustable delay means coupled to said threshold circuit for expanding said flaw signals from said threshold circuit, b. scan interval delay means coupled to said adjustable delay means for producing a delayed flaw signal approximately one scan interval after such flaw signal is received from said threshold circuit, and c. flaw gate means coupled to said scan interval delay means and said adjustable delay means for passing an output indicative of a flaw only on the first occurrence of a flaw signal during a scan interval, and rejecting subsequent flaw signals during adjacent successive scan intervals which occur at the same scan position.
Claim 7
Dependent Claim
146 words
A flaw detection system utilizing a laser scanner for detecting flaws on a surface of material, comprising a. a laser for emitting a beam of radiation, b. means for successively scanning said laser beam across a surface of material being analyzed, c. detector means for receiving radiation apPlied by said laser beam from said surface producing a signal in response to the intensity of the radiation applied to said detector means, d. threshold circuit means coupled to said detector means for producing a flaw output signal when the signals from said detector means exceed a predetermined level, and e. a flaw quantizer circuit coupled to said threshold circuit for passing an output indicative of a flaw only on the first occurrence of a flaw signal during a scan interval, and rejecting subsequent flaw signals during adjacent successive scan intervals which occur at the same scan position.
Claim 8
Dependent Claim
146 words
A flaw detection system utilizing a laser scanner for detecting flaws on a surface of material, comprising a. a laser for emitting a beam of radiation, b. means for successively scanning said laser beam across a surface of material being analyzed, c. detector means for receiving radiation apPlied by said laser beam from said surface producing a signal in response to the intensity of the radiation applied to said detector means, d. threshold circuit means coupled to said detector means for producing a flaw output signal when the signals from said detector means exceed a predetermined level, and e. a flaw quantizer circuit coupled to said threshold circuit for passing an output indicative of a flaw only on the first occurrence of a flaw signal during a scan interval, and rejecting subsequent flaw signals during adjacent successive scan intervals which occur at the same scan position.
Claim 9
Dependent Claim
120 words
The flaw detection system set forth in claim 6 wherein said flaw quantizer circuit comprises a. an adjustable delay means coupled to said threshold circuit for expanding said flaw signals from said threshold circuit, b. scan interval delay means coupled to said adjustable delay means for producing a delayed flaw signal approximately one scan interval after such flaw signal is received from said threshold circuit, and c. flaw gate means coupled to said scan interval delay means and said adjustable delay means for passing an output indicative of a flaw only on the first occurrence of a flaw signal during a scan interval, and rejecting subsequent flaw signals during adjacent successive scan intervals which occur at the same scan position.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-24 | 1977-06-25 | 1977-12-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-24 | 1981-06-25 | 1981-12-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-24 | 1985-06-25 | 1985-12-25 | $7700.00 | Window Closed / Lapsed |