US5004724A
Expired / Lapsed
US
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Superconductive quantum interference device for the non-destructive evaluation of metals
Assignee: International Superconductor Corp
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Filing: 1989-03-09
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Granted: 1991-04-02
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Expires: 2009-03-09
Abstract
Abstract High-T c superconductor quantum interference devices (SQUIDs) for noise-free, accurate measurements of defects and flaws in metal shapes and forms by measuring changes in the secondary magnetic field intensity around any point which is excited by a primary excitation current or by measuring changes in the impedance of the exciting coils. These measured changes are correlated to defects and flaws present in the metal.
Inventors
- 👤 Dilip K. De
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 10:10
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/12; G01R33/1238; G01N; G01N27/00; G01N27/72; G01N27/82; G01N27/90; G01N27/9006; G01R33/02; G01R33/035; G01R33/0354; G01R33/0358; Y; Y10; Y10S; Y10S505/00; Y10S505/70; Y10S505/701; Y10S505/702
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
170 words
A method of nondestructive evaluation of locations of flaws in a metal body, comprising the steps of: (a) positioning a high-critical-temperature superconductive quantum interference device having a pair of insulated junctions in a superconductor loop in a flux-sensing relationship to a location adjoining said body; (b) relatively displacing said body and said location; (c) while said body and said location are relatively displaced, exciting said body with a modulated alternating current and detecting with said device flux irregularities representing flaws in said body; (d) establishing locations of said flaws by the relative positions of said location and said body upon the detection of said flux irregularities, a plurality of said devices being connected in series are juxtaposed with said body; (e) demodulating a signal generated by the series-connected devices to form an output; and (f) connecting respective modulating coils inductively coupled to the respective high-critical-temperature superconductive quantum interference devices and connected to said output in a feedback path to form a flux-locked loop with said high-critical-temperature superconductive quantum interference devices.
Claim 2
Independent Claim
170 words
A method of nondestructive evaluation of locations of flaws in a metal body, comprising the steps of: (a) positioning a high-critical-temperature superconductive quantum interference device having a pair of insulated junctions in a superconductor loop in a flux-sensing relationship to a location adjoining said body; (b) relatively displacing said body and said location; (c) while said body and said location are relatively displaced, exciting said body with a modulated alternating current and detecting with said device flux irregularities representing flaws in said body; (d) establishing locations of said flaws by the relative positions of said location and said body upon the detection of said flux irregularities, a plurality of said devices being connected in series are juxtaposed with said body; (e) demodulating a signal generated by the series-connected devices to form an output; and (f) connecting respective modulating coils inductively coupled to the respective high-critical-temperature superconductive quantum interference devices and connected to said output in a feedback path to form a flux-locked loop with said high-critical-temperature superconductive quantum interference devices.
Claim 3
Dependent Claim
55 words
The method defined in claim 1 wherein said body is excited in step (c) by passing an alternating current through two series-connected coil wound in opposite senses around said body, said alternating current having a frequency between substantially 1 kHz and 1 MHz and being modulated with a modulating frequency which is a fraction thereof.
Claim 4
Dependent Claim
43 words
The method defined in claim 2, further comprising the step of energizing said modulation coils with a square-wave signal of a frequency of 10 kHz to 500 kHz modulated with a frequency of 1/2 to 1/20 of the frequency of the square-wave signal.
Claim 5
Dependent Claim
25 words
The method defined in claim 3 wherein said square-wave signal is modulated with a frequency which is 1/2 of the frequency of the square-wave signal.
Claim 6
Dependent Claim
40 words
The method defined in claim 2 wherein said body is composed of a ferromagnetic material, further comprising the step of applying a constant unidirectional magnetic field to said body as a bias magnetic field during nondestructive evaluation of the body.
Claim 7
Dependent Claim
32 words
The method defined in claim 2 wherein four of said high-critical-temperature superconductive quantum interference devices are juxtaposed with said body and constitute two parallel-connected pairs of series-connected high-critical-temperature superconductive quantum interference devices.
Claim 8
Independent Claim
146 words
A method of nondestructive evaluation of locations of flaws in a metal body, comprising the steps of: (a) positioning a high-critical-temperature superconductive quantum interference device having a pair of insulated junctions in a superconductor loop in a flux-sensing relationship to a location adjoining said body; (b) relatively displacing said body and said location; (c) while said body and said location are relatively displaced, exciting said body with a modulated alternating current and detecting with said device flux irregularities representing flaws in said body; and (d) establishing locations of said flaws by the relative positions of said location and said body upon the detection of said flux irregularities, said location being defined by a coil juxtaposed with said body and connected in series with a coil located remote from said body, said high-critical-temperature superconductive quantum interference device being juxtaposed with said coil located remote from said body.
Claim 9
Independent Claim
146 words
A method of nondestructive evaluation of locations of flaws in a metal body, comprising the steps of: (a) positioning a high-critical-temperature superconductive quantum interference device having a pair of insulated junctions in a superconductor loop in a flux-sensing relationship to a location adjoining said body; (b) relatively displacing said body and said location; (c) while said body and said location are relatively displaced, exciting said body with a modulated alternating current and detecting with said device flux irregularities representing flaws in said body; and (d) establishing locations of said flaws by the relative positions of said location and said body upon the detection of said flux irregularities, said location being defined by a coil juxtaposed with said body and connected in series with a coil located remote from said body, said high-critical-temperature superconductive quantum interference device being juxtaposed with said coil located remote from said body.
Claim 10
Independent Claim
147 words
A method of nondestructive evaluation of locations of flaws in a metal body, comprising the steps of: (a) positioning a high-critical-temperature superconductive quantum interference device having a pair of insulated junctions in a superconductor loop in a flux-sensing relationship to a location adjoining said body; (b) relatively displacing said body and said location; (c) while said body and said location are relatively displaced, exciting said body with a modulated alternating current and detecting with said device flux irregularities representing flaws in said body; (d) establishing locations of said flaws by the relative positions of said location and said body upon the detection of said flux irregularities, said location being defined by a coil juxtaposed with said body and connected in series with a coil located remote from said body; and (e) inductively coupling said coil located remote from said body with said high-critical-temperature superconductive quantum interference device.
Claim 11
Independent Claim
147 words
A method of nondestructive evaluation of locations of flaws in a metal body, comprising the steps of: (a) positioning a high-critical-temperature superconductive quantum interference device having a pair of insulated junctions in a superconductor loop in a flux-sensing relationship to a location adjoining said body; (b) relatively displacing said body and said location; (c) while said body and said location are relatively displaced, exciting said body with a modulated alternating current and detecting with said device flux irregularities representing flaws in said body; (d) establishing locations of said flaws by the relative positions of said location and said body upon the detection of said flux irregularities, said location being defined by a coil juxtaposed with said body and connected in series with a coil located remote from said body; and (e) inductively coupling said coil located remote from said body with said high-critical-temperature superconductive quantum interference device.
Claim 12
Independent Claim
163 words
An apparatus for nondestructive location of flaws in a metal body, comprising: a high-critical-temperature superconductive quantum interference device having a pair of insulated junctions in a superconductor loop disposed in flux-sensing relationship to a location adjoining said body; means for relatively displacing said body and said location; means for exciting said body with a modulated alternating current while said body and said location are relatively displaced, whereby said device detects flux irregularities representing flaws in said body; means for establishing locations of said flaws by the relative positions of said location and said body upon the detection of said flux irregularities, a plurality of said devices connected in series being juxtaposed with said body, means for demodulating a signal generated by the series-connected devices to form an output; and respective modulating coils inductively coupled to the respective high-critical-temperature superconductive quantum interference devices and connected to said output in a feedback path to form a flux-locked loop with said high-critical-temperature superconductive quantum interference devices.
Claim 13
Independent Claim
163 words
An apparatus for nondestructive location of flaws in a metal body, comprising: a high-critical-temperature superconductive quantum interference device having a pair of insulated junctions in a superconductor loop disposed in flux-sensing relationship to a location adjoining said body; means for relatively displacing said body and said location; means for exciting said body with a modulated alternating current while said body and said location are relatively displaced, whereby said device detects flux irregularities representing flaws in said body; means for establishing locations of said flaws by the relative positions of said location and said body upon the detection of said flux irregularities, a plurality of said devices connected in series being juxtaposed with said body, means for demodulating a signal generated by the series-connected devices to form an output; and respective modulating coils inductively coupled to the respective high-critical-temperature superconductive quantum interference devices and connected to said output in a feedback path to form a flux-locked loop with said high-critical-temperature superconductive quantum interference devices.
Claim 14
Dependent Claim
55 words
The apparatus defined in claim 9 wherein said body is excited in step (c) by passing an alternating current through two series-connected coils wound in opposite senses around said body, said alternating current having a frequency between substantially 1 kHz and 1 MHz and being modulated with a modulating frequency which is a fraction thereof.
Claim 15
Dependent Claim
42 words
The apparatus defined in claim 10, further comprising means for energizing said modulation coils with a square-wave signal of a frequency of 10 kHz to 500 kHz modulated with a frequency of 1/2 to 1/20 of the frequency of the square-wave signal.
Claim 16
Dependent Claim
39 words
The apparatus defined in claim 9 wherein said body is composed of a ferromagnetic material, further comprising means for applying a constant unidirectional magnetic field to said body as a bias magnetic field during nondestructive evaluation of the body.
Claim 17
Dependent Claim
32 words
The apparatus defined in claim 9 wherein four of said high-critical-temperature superconductive quantum interference devices are juxtaposed with said body and constitute two parallel-connected pairs of series-connected high-critical-temperature superconductive quantum interference devices.
Claim 18
Independent Claim
141 words
An apparatus for nondestructive location of flaws in a metal body, comprising: a high-critical-temperature superconductive quantum interference device having a pair of insulated junctions in a superconductor loop disposed in flux-sensing relationship to a location adjoining said body; means for relatively displacing said body and said location; means for exciting said body with a modulated alternating current while said body and said location are relatively displaced, whereby said device detects flux irregularities representing flaws in said body; and means for establishing locations of said flaws by the relative positions of said location and said body upon the detection of said flux irregularities, said location being defined by a coil juxtaposed with said body and connected in series with a coil located remote from said body, said high-critical-temperature superconductive quantum interference device being juxtaposed with said coil located remote from said body.
Claim 19
Independent Claim
141 words
An apparatus for nondestructive location of flaws in a metal body, comprising: a high-critical-temperature superconductive quantum interference device having a pair of insulated junctions in a superconductor loop disposed in flux-sensing relationship to a location adjoining said body; means for relatively displacing said body and said location; means for exciting said body with a modulated alternating current while said body and said location are relatively displaced, whereby said device detects flux irregularities representing flaws in said body; and means for establishing locations of said flaws by the relative positions of said location and said body upon the detection of said flux irregularities, said location being defined by a coil juxtaposed with said body and connected in series with a coil located remote from said body, said high-critical-temperature superconductive quantum interference device being juxtaposed with said coil located remote from said body.
Claim 20
Independent Claim
143 words
An apparatus for nondestructive location of flaws in a metal body, comprising: a high-critical-temperature superconductive quantum interference device having a pair of insulated junctions in a superconductor loop disposed in flux-sensing relationship to a location adjoining said body; means for relatively displacing said body and said location; means for exciting said body with a modulated alternating current while said body and said location are relatively displaced, whereby said device detects flux irregularities representing flaws in said body; means for establishing locations of said flaws by the relative positions of said location and said body upon the detection of said flux irregularities, said location being defined by a coil juxtaposed with said body and connected in series with a coil located remote from said body; and means for inductively coupling said coil located remote from said body with said high-critical-temperature superconductive quantum interference device.
Claim 21
Independent Claim
143 words
An apparatus for nondestructive location of flaws in a metal body, comprising: a high-critical-temperature superconductive quantum interference device having a pair of insulated junctions in a superconductor loop disposed in flux-sensing relationship to a location adjoining said body; means for relatively displacing said body and said location; means for exciting said body with a modulated alternating current while said body and said location are relatively displaced, whereby said device detects flux irregularities representing flaws in said body; means for establishing locations of said flaws by the relative positions of said location and said body upon the detection of said flux irregularities, said location being defined by a coil juxtaposed with said body and connected in series with a coil located remote from said body; and means for inductively coupling said coil located remote from said body with said high-critical-temperature superconductive quantum interference device.
References Cited (Backward Citations)
US3976934A
Cited
US4352065A
Cited
US4243939A
Cited
US4437064A
Cited
US4481471A
Cited
US4628261A
Cited
US4677379A
Cited
US4706021A
Cited
US4639675A
Cited
US4788504A
Cited
US4851776A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-04-01 | 1994-10-01 | 1995-04-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-04-01 | 1998-10-01 | 1999-04-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-04-01 | 2002-10-01 | 2003-04-02 | $7700.00 | Window Closed / Lapsed |