A5081977202- Geophysical Methods and Applications
- Microwave Imaging and Scattering Analysis
- Electromagnetic Compatibility and Measurements
- Electromagnetic Scattering and Analysis
- Planetary Science and Exploration
- Astro and Planetary Science
- Microwave and Dielectric Measurement Techniques
- Nuclear Physics and Applications
- Soil Moisture and Remote Sensing
- Advanced Antenna and Metasurface Technologies
- Plasmonic and Surface Plasmon Research
- Underwater Acoustics Research
- Metamaterials and Metasurfaces Applications
- Body Composition Measurement Techniques
- Seismic Imaging and Inversion Techniques
- Near-Field Optical Microscopy
- Numerical methods in inverse problems
- thermodynamics and calorimetric analyses
- Pickering emulsions and particle stabilization
- Thermal and Kinetic Analysis
- Optical measurement and interference techniques
- 3D Surveying and Cultural Heritage
- Characterization and Applications of Magnetic Nanoparticles
- Phase Equilibria and Thermodynamics
- Inorganic Fluorides and Related Compounds
Institut Fresnel
2014-2024
Centre National de la Recherche Scientifique
2013-2024
Aix-Marseille Université
2009-2024
Centrale Marseille
2013-2024
École Centrale Paris
2010-2011
Université Joseph Fourier
2007-2009
Cezanne (Italy)
2007
Institut des Matériaux, de Microélectronique et des Nanosciences de Provence
2005
Université Claude Bernard Lyon 1
1973-1994
Automation and Process Engineering Laboratory
1992-1994
The Philae lander provides a unique opportunity to investigate the internal structure of comet nucleus, providing information about its formation and evolution in early solar system. We present Comet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT) measurements interior 67P/Churyumov-Gerasimenko. From propagation time form signals, upper part "head" 67P is fairly homogeneous on spatial scale tens meters. CONSERT also reduced size uncertainty Philae's final landing site down...
In the present paper, experimental set-up of Institut Fresnel used to measure scattered fields different elongated objects is precisely described. Since special issue on ‘Testing inversion algorithms against data’, modifications this system, outlined here, have mostly been done improve synchronization apparatuses and precision our measurements. Due a large number requests from inverse problem community, it has decided add new measurements Fresnel's database. All targets presented here are...
A reconstruction algorithm is detailed for three-dimensional full-vectorial microwave imaging based on Newton-type optimization. The goal to reconstruct the complex permittivity of a scatterer in homogeneous background from number time-harmonic scattered field measurements. combines modified Gauss-Newton optimization method with computationally efficient forward solver, fast Fourier transform and marching-on-in-source-position extrapolation procedure. regularized cost function proposed by...
Abstract The future of ultra-fast optical communication systems is inevitably connected with progress in circuits and nanoantennas. One the key points this creation elementary components devices scattering diagrams tailored for redirecting incident light a desired manner. Here we demonstrate theoretically experimentally that small, simple, spatially homogeneous dielectric subwavelength sphere high refractive index low losses (as some semiconductors visible or near infrared region) exhibits...
We present a 3D spherical bistatic experimental setup developed in the anechoic chamber of Institut Fresnel Marseille, France, for scattering measurements targets microwave domain, both copolarization and cross‐polarization. first describe geometry setup, measurement protocol, calibration process. The results obtained different metallic dielectric are then compared to numerical simulations, computed either using coupled dipole method or Mie theory. These comparisons used validate algorithms...
Measurement accuracy is a key point when dealing with microwave scattering measurements of 3‐D targets. This even more drastic the targets are small compared to wavelength. In order be able fully exploit spherical multistatic setup and measure pattern from in copolarization cross polarization, detailed analysis experimental errors that disturb scattered field was carried out, measurement methodology derived. Such performed anechoic chamber Institut Fresnel Marseille, France. So far, our...
The authors propose a method to correct for drift errors which occur when performing three-dimensional scattering field measurements. This has the advantages of being fast, without loss information and with no need priori on scatterer. It is based properties limited spatial bandwidth scattered field.
Les relations thermodynamiques appliquées aux corps finement divisés conduisent à des expressions liant la température du point triple et l’énergie de changement d’état d’un dans un milieu poreux courbures interphases. Un examen solidification saturant qu’il mouille, permet d’envisager trois processus d’état. A chacun ces mécanismes correspond une relation particulière entre variation le rayon capillaire lequel a lieu transformation.
Les proprietes conductrices dans le systeme Cr-Se sont reliees a la structure cristalline. composes Cr2 Se3 et Cr3 Se4 semiconducteurs. energies d'activation de 0.156 eV 0.093 respectivement. Cr 7 Se8 possede une conduction metallique. CrSe stoechiometrique n'existe pas. Cr1-g Se (s ~ 2 %), prepare sans precipitation Cr,
This paper deals with the reconstruction of three-dimensional targets from experimental multiple-frequency data measured in anechoic chamber Institut Fresnel (Marseille, France). An inverse iterative scheme is implemented an adequate choice cost functional. Indeed, a Bayesian approach considered order to take into account random noise which present experiment. leads definition functional, where weighting coefficients are changing frequency, incidence angle and receiving angle. The inversion...
Une étude critique des diverses techniques mises en œuvre pour la détermination caractéristiques du changement d’état liquide [math] solide d’un corps finement divisé montre l’intérêt d’une méthode, telle que calorimétrie, qui permet l’observation phénomènes survenant au sein même capillaires.
An accurate knowledge of the complex permittivity value materials is compulsory when performing experimental electromagnetic applications. Unfortunately, these values are not so obvious to determine in practice. In this letter, we propose a novel approach for determining dielectric constant materials. This method combines free-space far-field scattering pattern measurements with Bayesian procedure, which fully exploits measurement uncertainties. Therefore, measured weighted according their...
We present an extensive experimental study of microwave scattering by a fully characterized complex aggregate. measured the full amplitude matrix (amplitude and phase four elements) for wide range configurations. The presented results are special interest to light community. Our experiments offer possibility validate numerical methods against experiments, since geometrical dielectric properties target known high degree precision, situation difficult attain in optical regime. analyze detail...
We present reconstructions of an aggregate small spheres from experimental scattered fields using a working frequency 18 GHz. This target presents at the same time complex 3D shape and low-contrast permittivity. Concerted numerical efforts have enabled to obtain accurate reconstructions. In particular, we took into account real random noise via Bayesian framework. Reconstructions been realized with measured in different polarization cases: results are compared discussed.
We report the experimental evidence of directional Fano resonances at scattering a linearly polarized electromagnetic plane wave by homogeneous dielectric sphere with high refractive index and low losses. observe typical asymmetric profile for intensity scattered in practically any given direction, while overall extinction cross section remains Lorentzian. The phenomenon originates interference selectively excited electric dipolar quadrupolar modes. selectivity excitation is achieved proper...
This article introduces and evaluates numerically a multigrid solver for non-linear tomographic radar imaging. Our goal is to enable the fast robust inversion of sparse time-domain data with mathematical full-wave approach utilizing higher-order Born approximation (BA). Full-wave computationally expensive, hence techniques speed up numerical procedures are needed. To model wave propagation effectively, we use finite element (FETD) method, which equipped scheme rapid evaluation BA. As...
This paper deals with the problem of reconstructing relative permittivity three-dimensional targets using experimental scattered fields. The fields concerned were measured in an anechoic chamber on surface a sphere surrounding target. inverse scattering is reformulated as optimization that iteratively solved thanks to conjugate gradient method and by coupled dipoles forward solver. measurement technique inversion procedure are briefly described results. work demonstrates reliability...
To accurately image a complex shape but large 3D target whose scattered field has been measured in an anechoic environment at high frequencies (18 and 20 GHz), we have developed complete imaging process, combining experimental numerical works. The adopted strategy exploits the maximum of available information related to measurements, both terms quantity accuracy without any priori knowledge on scatterer geometry. We first determine position then dimension spatial domain which contains...
The internal structure of a sample an absorber is retrieved from its measured scattered field. By very nature, this target weak-scatterer as it used to cover the walls in anechoic chambers. real part permittivity rather small but dielectric losses are non negligible. Quantitative maps complex were obtained monochromatic fields inside chamber multistatic configuration. An imaging procedure taking into account noise characteristics disturbing measurements was for purpose.
In tomography algorithms, the complex amplitude scattering matrix corresponds to input parameter. When considering 3D targets, now contains vectorial information. Thus, this might be calculated with various polarization projections. Moreover, when dealing experimental data, we are almost every time faced truncated data. We focus here on impact of selecting parts elements versus others and in particular influence choices imaging results. order better apprehend physical content associated each...