Search results for "INFRAROUGE"
showing 10 items of 36 documents
Suspended core tellurite glass optical fibers for infrared supercontinuum generation
2011
International audience; We report the fabrication and characterization of tellurite TeO(2)-ZnO-Na(2)O (TZN) microstructured suspended core optical fibers (MOFs). These fibers are designed for infrared supercontinuum generation with zero dispersion wavelength (ZDW) at 1.451 mu m. The measured losses at this wavelength are approximately 6 dB/m for a MOF with a 2.2 mu m diameter core. The effective area of a particular fiber is 3.5 mu m(2) and the nonlinear coefficient is calculated to be 437 W(-1)km(-1). By pumping a 20 cm long fiber at 1.56 mu m with a sub-nj femtosecond laser source, we generate a supercontinuum (SC) spanning over 800 nm in the 1-2 mu m wavelength range.
Tellurites fibers for infrared supercontinuum sources : opto-geometric profiles and extrinsic absorptions management
2016
This PhD thesis work focuses on the synthesis and purification of vitreous materials used for the development of waveguides with varied profiles, dedicated to supercontinuum (SC) generation between 1 and 5 μm.Concerning the purification of tellurite glasses, several leads were followed, but best results are obtained for the purification of the TeO2-ZnO-Na2O glassy system by the means of zinc fluoride. Attenuation measurements performed on several meter-long single-index fiber samples reveal the nearly complete elimination of water-related absorptions between 3 and 4 μm (OH ions concentration lower than 1 ppm mass.). Such water-purified glasses were firstly dedicated to microstructured optic…
Development of functionalizable azaBODIPYs for the conception of theranostic agents and bimodal probes for imaging uses
2020
The in vivo use of optical imaging is still limited by the lack of near infrared emitting probes. This thesis work focuses on the optimization and valorization of a water-soluble fluorescent platform whose optical properties enable an in vivo use. Two distinct applications were investigated for this WazaBY (Water-soluble azaBODIPY) platform: use as a PET (or SPECT) / optical bimodal probe, and as a theranostic agent. Concerning the first project, we were able to develop a targetted SPECT/optical bimodal probe, which was radiometallated with indium 111. Using xenografted murine models, we were able to show a clear accumulation of the probe in the tumor 24 hours after injection. Moreover, the…
Contribution to the study and to the optimization of active thermographic process applied to surface crack detection
2017
The aim of this work is the detection of open and subjacent defects in metallic materials using laser-material interaction coupled with infrared thermography. This process is a possible alternative for magnetic particles testing and dye penetrant testing in the field of non-destructive testing. This work is divided into three main parties. At first, we have been interested in the characterization of optical and thermophysical properties of materials we used, in order to have good boundary conditions and also for the needs of temperatures fields measurements for validation. The second part concern the development of a numerical simulation model with two step approach: the first involves mode…
Small-core chalcogenide microstructured fibers for the infrared.
2008
International audience; We report several small-core chalcogenide microstructured fibers fabricated by the "Stack & Draw" technique from Ge(15)Sb(20)S(65) glass with regular profiles. Mode field diameters and losses have been measured at 1.55 microm. For one of the presented fibers, the pitch is 2.5 microm, three times smaller than that already obtained in our previous work, and the corresponding mode field diameter is now as small as 3.5 microm. This fiber, obtained using a two step "Stack & Draw" technique, is single-mode at 1.55 microm from a practical point of view. We also report the first measurement of the attenuation between 1 and 3.5 microm of a chalcogenide microstructured fiber. …
Determination of energy fluxes in composite plates or processed by Vico-constrained damping patch
2021
Lightening structures is an important issue in the world of transport. On the other hand, for the improvement of comfort, increasing performance is demanded today, particularly in the vibratory and acoustic field, which leads to the addition of damping materials. The proposed research work consists in the vibrational optimization of the structures by the addition of viscoelastic patches damping positioned wisely. The main function of the viscoelastic used to improve the vibro-acoustic performances, is to provide a mechanism of dissipation of mechanical energy. This attenuation of noise and vibrations causes a conversion of mechanical energy into thermal energy, which, after diffusion into t…
Spectral interest points and texture extraction and fusion for identification, control and security
2018
Biometrics is an emerging technology that proposes new methods of control, identification and security. Biometric systems are often subject to risks. Face recognition is popular and several existing approaches use images in the visible spectrum. These traditional systems operating in the visible spectrum suffer from several limitations due to changes in lighting, poses and facial expressions. The methodology presented in this thesis is based on multispectral facial recognition using infrared and visible imaging, to improve the performance of facial recognition and to overcome the deficiencies of the visible spectrum. The multispectral images used in this study are obtained by fusion of visi…
UV resistance of Bacillus subtilis spores - Involvement of DPA and characterization by photonic microscopy
2022
The aim of this project was to study the UVc resistance of Bacillus subtilis spores. The first part of this project focused on the dipicolinic acid molecule (DPA) which is known to be involved in the UV resistance of spores. However, some points remain unresolved. In particular, it is known that this molecule forms fluorescent photoproducts (DPAp), which were not identified at the beginning of this project. No information concerning the role of these DPAp in UVC resistance was available at that time. During this project, a protocol was established to follow the appearance of these photoproducts directly inside the spore core. A method was also set up to artificially introduce DPAp into the …
Supercontinuum generation in chalcogenides : application to gas spectroscopy in atmospheric band III
2023
This thesis work aims to contribute to the development of new fiber sources emitting over a wide range of wavelengths in the IR, in particular to detect greenhouse gases in the mid-infrared range. Our spectroscopy results with nitrous oxide N2O and methane CH4 are obtained in band III. To achieve this, the generation of supercontinuum (SC) covering band III was made possible by using chalcogenide optical fibers, purified and free of highly toxic elements according to REACH regulations, in particular arsenic and antimony. The fibrable vitreous composition belonging to the Ge-Se-Te ternary system fits perfectly into the context of sustainable development, it is the one that has been identifie…
Contribution and limitation of infrared spectroscopy technique to understand physisorption processes on MFI zeolites
2011
This manuscript is devoted to the study of adsorption processes by FTIR spectroscopy. The experimental results concern the adsorption of ethylene, trichloroethylene, tetrachloroethylene, sulfur hexafluoride or p-xylene on MFI zeolites, more especially on silicalite-1. The first step of the work was to develop a new experimental device and procedure in order to obtain reliable absorption infrared data and to improve results previously obtained by a prototype. The first main result is to characterize, maybe for the first time, the evolution of the spectrum of the adsorbent all during the adsorption process. Experiments reveal that the zeolite infrared spectrum undergoes strong modifications w…