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1. Detection and Imaging of Magnetic Field in the Microwave Regime With a Combination of Magnetic Losses Material and Thermofluorescent Molecules

Author

Daniel Prost, Julian Carrey, François Issac, Jean-François Bobo, Stéphane Faure, Hugo Ragazzo, ONERA / DEMR, Université de Toulouse [Toulouse], ONERA-PRES Université de Toulouse, Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre d'élaboration de matériaux et d'études structurales (CEMES), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)

Subjects
010302 applied physics, Electromagnetic field, Materials science, Infrared, business.industry, Near and far field, 7. Clean energy, 01 natural sciences, thermography, [SPI.MAT]Engineering Sciences [physics]/Materials, Electronic, Optical and Magnetic Materials, Magnetic field, [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, Electromagnetism, Electric field, 0103 physical sciences, Thermography, Optoelectronics, fluorescence, magnetic losses, Electrical and Electronic Engineering, business, Microwave, Excitation
Abstract

International audience; Characterization of the electromagnetic field emitted by various sources (antenna, radar, etc.) is an important issue, either for civil or defense applications. The measurement of electromagnetic field may be performed either by local probes or by thermography imaging, in particular with an infrared camera. The latter method, called electromagnetic infrared (EMIR) has been developed several years ago. We have recently successfully implemented this technique in the domain of visible light thanks to the combination of a film sensitive to either electric field (slightly conductive film) or magnetic field (insulating film with ferromagnetic particles) and a polymer coating doped with fluorescent molecules with an emission depending on temperature, indeed a thermofluorescent sensor. We present our recent results obtained imaging the microwave magnetic field emitted in the near field of a zeroth-order resonator (ZOR) antenna. The sensing film is a stack of FLEX-TOKIN magnetic absorber, already tested by EMIR infrared thermography in our group. A 20 µm film composed of a mixture of rhodamine B (RhB) in an epoxy matrix is screen printed on the FLEX surface. RhB, in ethanol solution, has a thermofluorescence coefficient of ∼2%/K at room temperature at its maximum of fluorescence of 595 nm. Excitation light is delivered by an array of blue 470 nm LEDs. The 4.29 GHz microwave excitation of the ZOR device is amplitude modulated at 0.1-0.5 Hz in order to cancel any thermal drift and convection of the thermofluorescence image. Low-frequency excitation modulation also allows noise cancellation via image pixel demodulation postprocessing. We present the deduced temperature mapping of the sensing film placed 2 mm above the ZOR patch antenna.

Published
2019
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2. Thermo-fluorescent images of electric and magnetic near-fields of a High Impedance Surface

Author

Daniel Prost, Jean-François Bobo, Julian Carrey, Stephane Faure, François Issac, Hugo Ragazzo, ONERA / DEMR, Université de Toulouse [Toulouse], ONERA-PRES Université de Toulouse, Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre d'élaboration de matériaux et d'études structurales (CEMES), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)

Subjects
Electromagnetic field, THERMOGRAPHY, Materials science, Field (physics), Infrared, 02 engineering and technology, 01 natural sciences, THERMOGRAPHIE, ELECTROMAGNETISME, [SPI]Engineering Sciences [physics], Optics, Electromagnetism, Electric field, 0103 physical sciences, MAGNETIC LOSSES, FLUORESCENCE, 010302 applied physics, PERTES MAGNETIQUES, [PHYS]Physics [physics], business.industry, 021001 nanoscience & nanotechnology, ELECTROMAGNETISM, HIGH IMPEDANCE SURFACE, SURFACE HAUTE IMPEDANCE, Magnetic field, Thermography, PERTES ELECTRIQUES, Antenna (radio), 0210 nano-technology, business, ELECTRIC LOSSES
Abstract

International audience; Characterization of the electromagnetic field emitted by various sources (antenna, radar...) is an important issue, either for civil or defense applications. The measurement of the electromagnetic field may be performed by a local probe, but the infrared thermography imaging is an alternative way. The latter method, called EMIR [1] (ElectroMagnetic InfraRed) has been used for years in particular at ONERA where it had been developed. We have recently successfully implemented this technique in the domain of visible light, named as EMVI [2]. As in the EMIR method, a thin film (sensitive to either electric field or magnetic field) is heated by the emitted field. But here the film is coated with a polymer doped with fluorescent molecules. As the fluorescent emission depends on the temperature of the film, we get a thermofluorescent sensor. The results presented here illustrate that new method: both magnetic and electric field imaging of a High Impedance Surface (HIS) have thus been obtained.

Published
2019

3. Electromagnetic Field Intensity Imaging by Thermofluorescence in the Visible Range

Author

François Issac, Stéphane Faure, Daniel Prost, Julian Carrey, Jean-François Bobo, VALEO, Centre d'élaboration de matériaux et d'études structurales (CEMES), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), ONERA / DEMR, Université de Toulouse [Toulouse], ONERA-PRES Université de Toulouse, Laboratoire de physique et chimie des nano-objets (LPCNO), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), and Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)

Subjects
Electromagnetic field, Materials science, Field (physics), business.industry, General Physics and Astronomy, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Magnetic field, Resonator, [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, Optics, Electric field, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Antenna (radio), 010306 general physics, 0210 nano-technology, business, Noise (radio), Microwave
Abstract

International audience; Methods to measure the electromagnetic field intensity on a large scale should be improved to meet the growing demand in civil and military applications. The recent development and an application of a microwave electromagnetic field imaging method using a thermofluorescent device and detection in the visible-light range are described. The sensor is a flexible film sensitive to either an electric field (slightly conductive film) or a magnetic field (insulating film with ferromagnetic particles) coated with a polymer doped with fluorescent molecules displaying temperature-dependent emission. We use a lock-in thermog-raphy protocol consisting of modulation of the field at low frequency, which allows us to suppress the noise due to heat-transfer phenomena and the part of the signal not directly related to field absorption. Two applications of the method are presented: (i) imaging the microwave magnetic field emitted by a resonator antenna and (ii) the local probe measurement of the electric field inside a multibeam antenna. The process to develop the sensitive film, its detailed characterization, and the thermofluorescence-image demodula-tion postprocessing are presented in detail. This approach is much cheaper than one based on infrared thermometry and could permit democratization of microwave-and radio-frequency electromagnetic field imaging.

Published
2019
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4. Microwave Magnetic Field Imaging Using Thermo-Emissive Ferromagnetic Micro-Structured Films

Author

Jean-François Bobo, Daniel Prost, F. Boust, François Issac, and Jerome Vernieres

Subjects
Materials science, business.industry, Ferromagnetic resonance, Electronic, Optical and Magnetic Materials, law.invention, Magnetic field, Condensed Matter::Materials Science, Magnetic anisotropy, Magnetic field imaging, Nuclear magnetic resonance, law, Permeability (electromagnetism), Eddy current, Optoelectronics, Electrical and Electronic Engineering, Thin film, business, Microwave
Abstract

A new microwave magnetic field measurement method based on infrared emission is presented. This method uses thin patterned ferromagnetic films sputtered on polymer substrates. The incident field interacts with the film and is responsible for ferromagnetic losses that create local heating. This heating is recorded by an infrared camera, providing magnetic field pattern images and amplitude evaluation. Moreover, the tangential components of the H field can be identified thanks to the anisotropic structure of the sputtered film. The large permeability NiFe based thin films were grown using a sputtering method and complex permeability measurements have been carried out in the microwave range. Both infrared pictures and magnetic permeability measurements are presented and correlated.

Published
2011
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5. Static and dynamic magnetic properties of epitaxial Co2FeAl Heusler alloy thin films

Author

Coriolan Tiusan, Michel Hehn, M. S. Gabor, G. Ortiz, François Issac, J. F. Bobo, F. Boust, and Traian Petrisor

Subjects
Magnetization, Materials science, Annealing (metallurgy), Metallurgy, Analytical chemistry, General Physics and Astronomy, Thin film, Atmospheric temperature range, Epitaxy, Saturation (magnetic), Ferromagnetic resonance, Single crystal
Abstract

Structural and magnetic properties of epitaxial Co2FeAl Heusler alloy thin films were investigated. Films were deposited on single crystal MgO (001XS) substrates at room temperature, followed by an annealing process at 600 °C. MgO and Cr buffer layers were introduced in order to enhance crystalline quality, and improve magnetic properties. Structural analyses indicate that samples have grown in the B2 ordered epitaxial structure. VSM measures show that the MgO buffered sample displays a magnetization saturation of 1010 ± 30 emu/cm3, and Cr buffered sample displays a magnetization saturation of 1032 ± 40 emu/cm3. Damping factor was studied by strip-line ferromagnetic resonance measures. We observed a maximum value for the MgO buffered sample of about 8.5 × 10−3, and a minimum value of 3.8 × 10−3 for the Cr buffered one.

Published
2011
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6. Ferromagnetic microstructured thin films with high complex permeability for microwave applications

Author

François Issac, F. Boust, Jean-François Bobo, Jerome Vernieres, and Daniel Prost

Subjects
Materials science, business.industry, General Physics and Astronomy, Ferromagnetic resonance, Magnetic field, Condensed Matter::Materials Science, Magnetic anisotropy, Optics, Ferromagnetism, Dielectric heating, Thin film, Anisotropy, business, Microwave
Abstract

Ferromagnetic microstructured films of Ni80Fe20 with in-plane uniaxial anisotropy were prepared by RF magnetron sputtering and patterned into rectangles with the larger dimension parallel to the easy axis. Static properties have been measured using a magneto-optic-Kerr-effect test bench, and dynamic properties were also obtained in the microwave frequency range. Because of ferromagnetic resonance, high complex permeability is obtained, and this corresponds to losses that create local heating. So, at an appropriate frequency, a microwave incident magnetic field interacts with the film and generates heating. This heating is recorded using an infrared camera to provide magnetic field pattern images. This setup yields qualitative results and allows for magnetic field detection on a large dimension scale.

Published
2011
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7. Microwave-assisted switching of NiFe magnetic microstructures

Author

M. Laval, François Issac, Jean-François Bobo, F. Boust, and J. J. Bonnefois

Subjects
History, Materials science, Condensed matter physics, Chemistry, Direct current, Analytical chemistry, Resonance, General Physics and Astronomy, Magnetostatics, Electromagnetic radiation, Computer Science Applications, Education, Magnetic field, Switching time, Magnetization, Magnetic shape-memory alloy, Radio frequency, Micromagnetics, Microwave, Excitation
Abstract

We have calculated, by either macrospin analytical method or micromagnetic numerical solving, the microwave assisted switching of a small rectangular platelet as a function of the amplitude and the frequency of a microwave excitation field. The spectral analysis of this phenomenon reveals that microwave-assisted switching is optimal for a rf frequency slightly lower than the linear magnetic resonance frequency measured at low level. Similar experimental results, obtained on 100 μm-scale NiFe structures reveal the same tendency. Switching time for such a process was obtained from calculations that show that sub-nanosecond switching times require combinations of large dc (direct current) and rf (radio frequency) magnetic fields.

Published
2009
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