EP1639359A1 - Magneto-optical imaging method and device - Google Patents
Magneto-optical imaging method and deviceInfo
- Publication number
- EP1639359A1 EP1639359A1 EP04767451A EP04767451A EP1639359A1 EP 1639359 A1 EP1639359 A1 EP 1639359A1 EP 04767451 A EP04767451 A EP 04767451A EP 04767451 A EP04767451 A EP 04767451A EP 1639359 A1 EP1639359 A1 EP 1639359A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- magnetic field
- active material
- target material
- faraday
- target
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/21—Polarisation-affecting properties
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
- G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
- G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/032—Measuring direction or magnitude of magnetic fields or magnetic flux using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect
- G01R33/0322—Measuring direction or magnitude of magnetic fields or magnetic flux using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect using the Faraday or Voigt effect
Definitions
- the invention relates to the field of magneto-optical imaging methods and devices. More particularly, the invention relates to a magneto-optical imaging method comprising: - the positioning, near a target material, of a substantially planar face of a magnetic active material suitable for generating a Faraday rotation in a beam polarized light, - the generation of a pulsating excitation magnetic field ⁇ in the target material, - the projection of a polarized light incident beam, through the active material, towards the target material, - detection, by means photo-detectors, of a reflected beam corresponding to the reflection on a reflecting surface located between the active material and the target material, and - the observation of the Faraday rotation angle in the reflected beam, with respect to the incident beam , created in the active material by a magnetic disturbance field generated by the target material.
- the invention provides in particular a process which, in addition to the characteristics already mentioned, is characterized by the fact that: - the Faraday rotation of the active material is substantially proportional to its magnetic magnetization when it is subjected to a magnetic disturbance field, perpendicular to said face and varying in a minimum range ranging between substantially -1 Oersteds and substantially +1 Oersteds, and that - we determine, from the value of the angle of rotation Faraday , the value of the magnetization of the active material, under the effect of the disturbance magnetic field.
- the invention and in particular thanks to the use of an active material whose Faraday rotation is proportional to the field in which it bathes, it is possible to determine, from a local light intensity, the value, in module and in phase, of the characteristic magnetic disturbance field due to defects in the target material. We can thus access, in real time, a map of the target material precisely characterizing the defects (corrosion depth, dimension cracks, etc.), in particular when the method according to the invention is combined with modeling of the means for generating the excitatory magnetic field.
- the method according to the invention may also include one and / or the other of the following arrangements: - the exciting magnetic field is generated by means of an inductor supplied by a variable exciting current; - It includes a measurement, by synchronous detection, of the variation of the phase of the magnetic disturbance field compared to that of the excitation current; - the amplitude of the disturbance magnetic field is measured from the light intensity of the reflected beam; - The incident beam is amplitude modulated at the same frequency as that of the excitation field.
- the invention relates to a magneto-optical imaging device, for forming an image of a target material, this device comprising: - an active material, having a substantially planar, magnetic face and suitable for generating a rotation Faraday in a polarized light beam, - means generating a pulsating excitation magnetic field ⁇ in the active material and in the target material when the imaging device is placed near this target material, - a light source for projecting an incident light beam polarized, through the active material, towards the target material, when the imaging device is placed near this target material, - photo-detector means, for detecting a reflected beam corresponding to the reflection after crossing of the active material, of the incident beam on a reflecting surface, characterized in that the Faraday rotation of the active material is substantially proportional to its magnetic magnetization when it is subjected to a disturbing magnetic field generated in the target material, perpendicular to said face and varying in a minimum range ranging between substantially -1 Oersteds and substantially +1
- the device according to the invention may also comprise one and / or the other of the following provisions: - it comprises an inductor supplied by a variable excitation current, to generate the excitatory magnetic field, - it comprises modulation means of the incident beam to modulate it in amplitude at the same frequency as that of the excitation field; and - it comprises calculation means for determining, from the value of the angle of rotation Faraday, the value of the magnetization of the active material, under the effect of a disturbing magnetic field generated in the material active, by the target material when the imaging device is placed near this target material.
- FIG. 1 shows schematically in perspective a magneto-optical imaging device according to the present invention
- - Figure 2 schematically shows the principle of magneto-optical modulation of the device shown in Figure 1
- - Figure 3 shows the magnetization cycle of the active material used in the constitution of the device shown in Figure 1
- - Figure 4 shows an image of the real part of the component of the disturbance magnetic field divided by the average light intensity, this image having been produced with a device of the type shown in Figure 1
- FIG. 5 represents an image of the imaginary part of the magnetic disturbance field, divided by the average light intensity, this image having been produced with a device of the type of that represented in FIG. 1.
- the device comprises: - a housing 1 adapted to be moved on the surface of a target material 2 that l 'we wish to analyze, - an optical device 3, - means for generating excitatory magnetic field 5, - photodetector means 7. More specifically, the optical device 3 comprises a light source 9, a polarizer 11 and an analyzer 13. The polarizer 11 and the analyzer 13 are of a type known to those skilled in the art.
- the light source 9 is for example made up of a light-emitting diode. Strong diodes Brightnesses are commercially available for various wavelengths.
- a red diode 10 mm in diameter and of high brightness will be chosen (reference TLRH190P from the company TOSHIBA).
- An optically active material 15 is interposed between the polarizer 11 and the analyzer 13, on the optical path.
- This polarizer / active material / analyzer assembly constitutes a magneto-optical light modulator.
- the principle of this magneto-optical modulator is illustrated in FIG. 2.
- the polarizer 11 and the analyzer 13 are crossed at an angle v. This angle v is advantageously chosen between 45 and 90 degrees.
- the plane of polarization rotates under the effect of the Faraday rotation by an angle p.
- the optically active material 15 is for example a ferrimagnetic garnet having a soft, linear magnetization cycle and with little hysteresis. It is for example a compound (GdPrBiTm) 3 (AlFe) 5 0 ⁇ 2 deposited in a film 5.9 ⁇ m thick, by epitaxy in liquid phase at 768 ° C, on a SGGG substrate [(GdCa ) 3 (Ga gZr) 5 0 ⁇ 2 ] of an inch in diameter.
- the direction of easy magnetization is normal to the plane of the film.
- the Bi 3+ and Pr 3+ ions make it possible to obtain a high Faraday rotation.
- the magnetic domains of this type of garnet are small compared to the size of the pixels of the photodetector means 7, which makes it possible to average the contributions of the domains of opposite direction of magnetization.
- the magnetization curve of such a garnet has a substantially linear part between -100 Oersteds and +100 Oersteds approximately.
- the hysteresis is negligible and that, very advantageously, the slope, in the linear part, is greater than 1 degree / Am -1 .
- the frequency f is for example 100 kHz.
- the magnetic field generating means 5 are for example constituted by an inductor plate 17 adapted to induce eddy currents in the target 2 (see FIG. 1).
- This inductor plate 17 is supplied with a sinusoidal current I having an effective value of 120A and a frequency f of 100kHz.
- This inductor plate 17 is made of copper.
- the magnetic field produced by the induction plate is approximately lkA / m.
- the induction plate 17 is parallel to the film of active material 15.
- a disturbance field H 0 is observed normal to the surface scanned with the face of the housing 1 parallel to the inductor plate 17.
- the photodetector means 7 advantageously consist of a matrix, rather than a single sensor associated with a mechanical scanning device.
- An analog CCD camera associated with a video capture card is appropriate. This is for example the model XC-75CE from the company SONY.
Landscapes
- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Power Engineering (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Pathology (AREA)
- Analytical Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Electrochemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Measuring Magnetic Variables (AREA)
- Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR0307850A FR2856791B1 (en) | 2003-06-27 | 2003-06-27 | METHOD AND DEVICE FOR MAGNETO-OPTICAL IMAGING |
PCT/FR2004/001602 WO2005001467A1 (en) | 2003-06-27 | 2004-06-24 | Magneto-optical imaging method and device |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1639359A1 true EP1639359A1 (en) | 2006-03-29 |
Family
ID=33515498
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP04767451A Withdrawn EP1639359A1 (en) | 2003-06-27 | 2004-06-24 | Magneto-optical imaging method and device |
Country Status (5)
Country | Link |
---|---|
US (1) | US7271900B2 (en) |
EP (1) | EP1639359A1 (en) |
CA (1) | CA2530197C (en) |
FR (1) | FR2856791B1 (en) |
WO (1) | WO2005001467A1 (en) |
Families Citing this family (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2901025B1 (en) | 2006-05-12 | 2008-12-26 | Centre Nat Rech Scient | FOURCAULT CURRENT IMAGING METHOD AND DEVICE FOR DETECTING AND CHARACTERIZING BURNED DEFECTS IN COMPLEX STRUCTURES. |
US8659291B2 (en) * | 2008-12-31 | 2014-02-25 | Infinitum Solutions, Inc. | Magneto-optical detection of a field produced by a sub-resolution magnetic structure |
US8289818B2 (en) | 2008-12-31 | 2012-10-16 | Infinitum Solutions, Inc. | Magneto-optic write-head characterization using the recording medium as a transducer layer |
FR2955666B1 (en) * | 2010-01-26 | 2012-04-13 | Centre Nat Rech Scient | METHOD FOR ESTIMATING DEFECTS IN AN OBJECT AND DEVICE FOR IMPLEMENTING SAID METHOD |
US8427929B2 (en) | 2010-09-08 | 2013-04-23 | Infinitum Solutions, Inc. | Sub-optical-resolution kerr signal detection for perpendicular write-head characterization |
WO2012049538A1 (en) * | 2010-10-12 | 2012-04-19 | Indian Institute Of Technology Kanpur | Systems and methods for imaging characteristics of a sample and for identifying regions of damage in the sample |
JP6037386B2 (en) * | 2013-02-13 | 2016-12-07 | 株式会社日立製作所 | Inspection apparatus and inspection method |
JP6484051B2 (en) * | 2015-02-10 | 2019-03-13 | 浜松ホトニクス株式会社 | Inspection method and inspection apparatus |
JP6632327B2 (en) | 2015-10-30 | 2020-01-22 | 浜松ホトニクス株式会社 | Image generation method, image generation device, image generation program, and recording medium |
EP3290997B1 (en) * | 2016-09-02 | 2020-07-01 | Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. | Magneto-optical light modulator |
US20240027546A1 (en) * | 2022-07-20 | 2024-01-25 | General Electric Company | Magneto-Optic Defect Visualization System |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1980001016A1 (en) * | 1978-11-01 | 1980-05-15 | Hitachi Ltd | Magneto-optical anisotropy detecting device |
US4625167A (en) * | 1983-07-05 | 1986-11-25 | Sigma Research, Inc. | Flaw imaging in ferrous and nonferrous materials using magneto-optic visualization |
US4755752A (en) * | 1983-07-05 | 1988-07-05 | Gerald L. Fitzpatrick | Flaw imaging in ferrous and nonferrous materials using magneto-optic visualization |
JPH0766044B2 (en) * | 1985-06-29 | 1995-07-19 | 株式会社東芝 | Magnetic field sensor |
JPH01209356A (en) * | 1988-02-18 | 1989-08-23 | Maakutetsuku Kk | Magnetic flaw detector for long-sized steel material |
JPH0670651B2 (en) * | 1988-07-09 | 1994-09-07 | 日本碍子株式会社 | Method and device for measuring electric and magnetic quantities by light |
US5053704A (en) * | 1990-01-11 | 1991-10-01 | Pri Instrumentation, Inc. | Flow imager for conductive materials |
DE4021359A1 (en) * | 1990-07-05 | 1992-01-09 | Siemens Ag | Detecting covered current paths in highly integrated circuits - using magneto=optical film and device to produce contrast image |
JPH0782164B2 (en) * | 1991-04-25 | 1995-09-06 | 松下電器産業株式会社 | Magneto-optical element and magnetic field measuring device |
US5446378A (en) * | 1993-12-15 | 1995-08-29 | Grumman Aerospace Corporation | Magneto-optic eddy current imaging apparatus and method including dithering the image relative to the sensor |
-
2003
- 2003-06-27 FR FR0307850A patent/FR2856791B1/en not_active Expired - Lifetime
-
2004
- 2004-06-24 WO PCT/FR2004/001602 patent/WO2005001467A1/en active Application Filing
- 2004-06-24 EP EP04767451A patent/EP1639359A1/en not_active Withdrawn
- 2004-06-24 CA CA2530197A patent/CA2530197C/en not_active Expired - Fee Related
- 2004-06-24 US US10/562,560 patent/US7271900B2/en not_active Expired - Fee Related
Non-Patent Citations (2)
Title |
---|
None * |
See also references of WO2005001467A1 * |
Also Published As
Publication number | Publication date |
---|---|
US7271900B2 (en) | 2007-09-18 |
FR2856791B1 (en) | 2005-11-04 |
FR2856791A1 (en) | 2004-12-31 |
WO2005001467A1 (en) | 2005-01-06 |
CA2530197C (en) | 2014-04-22 |
WO2005001467A8 (en) | 2005-05-06 |
US20060146328A1 (en) | 2006-07-06 |
CA2530197A1 (en) | 2005-01-16 |
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Legal Events
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Effective date: 20060811 |
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DAX | Request for extension of the european patent (deleted) | ||
RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: PLACKO, DOMINIQUE Inventor name: LEPOUTRE, FRANCOIS Inventor name: DECITRE, JEAN-MARC Inventor name: LEMISTRE, MICHEL Inventor name: JOUBERT, PIERRE-YVES Inventor name: BEN YOUSSEF, JAMAL |
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STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
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Effective date: 20180404 |