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Inverse problems based self-calibrated reconstruction for tomographic diffractive microscopy
No full textInternational audienceIn this work we propose an inverse problems based iterative reconstruction method for tomographic diffractive microscopy, involving measurements in off-axis configuration. More precisely, we propose a strategy that aims to eliminate reconstruction errors that can be caused by perturbations in the illumination wave of the reference arm. Our original contribution is to build the inverse problem considering as unknowns both the targeted 3D sample map and the perturbation map, that are jointly reconstructed and unmixed during the iterative process. This self-calibration process is rendered possible by the multiplicity of sample observations from multiple views, where the reference perturbed background remains invariant. We validate the feasibility of our approach on reconstructions from simulated data under different experimental conditions
Analysis of the Thermal Annealing Regeneration Process of RPL Dosimeters for High Dose Levels
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Synthetic Monoclass Teachers Distillation in the Edge using Federated Learning Approach
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Unraveling the electronic properties in SiO2 under ultrafast laser irradiation
No full textInternational audienceFirst-principles simulations were conducted to explore various electronic properties of crystalline SiO 2 (α-quartz) under ultrafast laser irradiation. Employing Density Functional Perturbation Theory and the many-body (GW) approximation, we calculated the impact of thermally excited electrons on the electronic specific heat, electron pressure, effective mass, deformation potential, electron-phonon coupling and electron relaxation time of quartz, covering a wide range of electron temperatures, up to 100,000 K. We show that the electron-phonon relaxation time of highly-excited quartz becomes twice faster compared to low-excited states. The deformation potential, which dictates atomic displacement, has a non-monotonic behavior with a well-pronounced minimum at around 16,000 K (2.7 × 10 21 cm -3 of excited electrons) where the bond ionicity of the Si-O starts decreasing followed by a cohesion loss at 35,000 K due to the pressure exerted by the excited electrons on the lattice. Consequently, our calculated data, illustrating the evolution of physical parameters, can facilitate simulations of laser-matter interactions and provide predictive insights into the behavior of quartz under experimental conditions.</div
L'intelligence artificielle à la lumière de la mythologie grecque : rendre compréhensible les impacts de l'IA pour le grand public
No full textArticle en version étendue de la présentation à la journée "Société & IA" de PFIA 2024National audienceDepuis les années 2010 et l'arrivée des modèles d'apprentissage profond, l'intelligence artificielle (IA) est un domaine qui s'est fait connaître du grand public. Face à une mauvaise compréhension de ce que peut faire l'intelligence artificielle, de ses limites et ses dangers, mais aussi comment utiliser cette technologie à bon escient, une manière originale de présenter l'IA est proposée sous la forme d'une analogie avec des légendes issues de la mythologie grecque afin d'être plus accessible aux personnes plutôt tournées vers les humanités que vers les sciences du numérique.</div
Modulation of electrical, acoustic and optical properties of phthalocyanines by gas adsorption: interest for gas sensors development
No full textInternational audiencePhthalocyanines constitute an extended family of molecular semi-conductors that possess specific optical, electrical and adsorption properties due to their high aromaticity and the extended delocalization of π-electrons. The adsorption of various gases can lead to the modulation of these properties involving different interactions between gases and materials: redox reaction, π-stacking, repulsion forces. Thus, the electronic conductivity, the mass and the optical index of phthalocyanine layers can be significantly modified by gas even for very low concentrations. Such sensing materials appear as highly relevant for the development of chemical micro-sensors exhibiting high sensitivity, low limit of detection and high resolution. The selectivity can be performed by the implementation of appropriate transducers: conductimetric, acoustic or optical.This lecture is focused on the gas/phthalocyanines interaction mechanisms and their effects on material properties. Strategies for the elaboration of gas sensors dedicated to target gases are described. The key role of transducer on the discrimination of the target gas is highlighted. Illustrated by relevant results, it is manifest that phthalocyanines layered on conductimetric transducers give highly selective sensor responses to nitrogen dioxide NO2 while selective responses towards aromatic hydrocarbons (BTEX) are obtained with acoustic transducers. In contrast, phthalocyanines associated to surface plasmon resonance transducer deliver higher responses to ammonia NH3. Beyond selectivity, metrological performances of all micro-sensors will be assessed and discussed
Application on Clinical Data of Robust Estimation of PpIX in Multispectral Excited Fluorescence Spectroscopy
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Femtosecond Drift Photocurrents Generated by an Inversely Designed Plasmonic Antenna
No full textInternational audiencePhotocurrents play a crucial role in various applications, including light detection, photovoltaics, and THz radiation generation. Despite the abundance of methods and materials for converting light into electrical signals, the use of metals in this context has been relatively limited. Nanostructures supporting surface plasmons in metals offer precise light manipulation and induce light-driven electron motion. Through inverse design optimization of a gold nanostructure, we demonstrate enhanced volumetric, unidirectional, intense, and ultrafast photocurrents via a magneto-optical process derived from the inverse Faraday effect. This is achieved through fine-tuning the amplitude, polarization, and their gradients in the local light field. The virtually instantaneous process allows dynamic photocurrent modulation by varying optical pulse duration, potentially yielding nanosources of intense, ultrafast, planar magnetic fields, and frequency-tunable THz emission. These findings open avenues for ultrafast magnetic material manipulation and hold promise for nanoscale THz spectroscopy
Two-photon interference and the Hong-Ou-Mandel effect
No full textInternational audienceThe Hong-Ou-Mandel (HOM) experiment is a landmark in quantum optics. A labwork version of this famous twophoton interference effect was developed at Institut d’Optique for students in engineering and MSc tracks. The setup enables the observation of the iconic HOM “dip” and the measurement of photon indistinguishability
STE-QUEST: Space Time Explorer and QUantum Equivalence principle Space Test
No full textAs submitted to the M7 call in July 2022, except updated for the recent (Sept. 2022) MICROSCOPE results, and new section 2.5 summarizing the information provided to ESA during the September 2022 auditionAn M-class mission proposal in response to the 2021 call in ESA's science programme with a broad range of objectives in fundamental physics, which include testing the Equivalence Principle and Lorentz Invariance, searching for Ultralight Dark Matter and probing Quantum Mechanics