References of "Georges, Marc"
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See detailSpace mirror deformation: from thermo- mechanical measurements by speckle interferometry to optical comparison with multiphysics simulation
Languy, Fabian ULiege; Vandenrijt, Jean-François ULiege; Saint-Georges, Philippe et al

in Applied Optics (2018), 57(24), 6982

Experimental testing of space optics is a mandatory process for investigating the optical performances in conditions close to reality. With the optical requirement level increasing over years, these ... [more ▼]

Experimental testing of space optics is a mandatory process for investigating the optical performances in conditions close to reality. With the optical requirement level increasing over years, these experimental tests are increasingly expensive and time-consuming. A modeling tool would therefore be an elegant solution to avoid these drawbacks. For this purpose, a multiphysics approach has been used to predict how optics behave under thermal loads. In this paper, experimental surface deformations of a space mirror perturbed by thermal gradients are compared to multiphysics simulation results. The local displacements of the mirror surface have been measured by use of electronic speckle pattern interferometry, and the deformation itself has been calculated by subtracting the rigid body motion. After validation of the thermo-mechanical solution, experimental and numerical wavefront errors are compared. [less ▲]

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See detailDigital Holographic Interferometry in the Long-Wave Infrared Range for Measuring Large Deformations of Space Components under Thermal-Vacuum Testing
Vandenrijt, Jean-François ULiege; Thizy, Cédric ULiege; Languy, Fabian ULiege et al

in Proceedings (2018, July 09), 2018(2), 534

Holographic interferometry at around 10 µm wavelengths has many advantages. It offers the possibility of large deformation measurement, while being much less sensitive to external perturbations. We ... [more ▼]

Holographic interferometry at around 10 µm wavelengths has many advantages. It offers the possibility of large deformation measurement, while being much less sensitive to external perturbations. We present the state-of-the art of this technique applied to several industrial cases of the space industry. In particular, we demonstrate that the technique is well adapted to measurement of full-field deformation maps of space structures undergoing large temperature variations typical to what they experience in space conditions. [less ▲]

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See detailLaser ultrasound flexible system for non-contact inspection of medium size and complex shaped composite structures made of carbon fiber reinforced polymer
Vandenrijt, Jean-François ULiege; Languy, Fabian ULiege; Thizy, Cédric ULiege et al

in Proceedings (2018, June 22), 2018(2), 455

We present the development of a contactless laser ultrasound system for nondestructive inspection of CFRP complex structures. Ultrasound are generated by a thermoelastic effect resulting from a green ... [more ▼]

We present the development of a contactless laser ultrasound system for nondestructive inspection of CFRP complex structures. Ultrasound are generated by a thermoelastic effect resulting from a green pulsed laser insulating a point of the inspected part. The resulting displacement of the surface point is probed by a two-wave mixing based interferometer working in the near infrared. The system is flexible and completely fiber-coupled. It is able to provide C-scans on complex shaped CFRP aeronautical structures. [less ▲]

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See detailThermography and Shearography Inspection of Composite Hybrid Sandwich Structure Made of CFRP and GFRP Core and Titanium Skins
Georges, Marc ULiege; Srajbr, Christian; Menner, Philipp et al

in Proceedings (2018, June 22), 2018(2), 484

We have investigated several full-field contactless techniques, such as thermography and shearography, with several excitation methods for inspecting hybrid composite-metal sandwich structures. The latter ... [more ▼]

We have investigated several full-field contactless techniques, such as thermography and shearography, with several excitation methods for inspecting hybrid composite-metal sandwich structures. The latter are made of a core with epoxy reinforced by carbon and glass fibers and skins of titanium. Several calibrated defects are incorporated at different places in depth and are made of air gaps and inserts. [less ▲]

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See detailImagerie Terahertz pour l’inspection des composites
Georges, Marc ULiege; Zhao, Yuchen ULiege

Conference given outside the academic context (2018)

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See detailThermal infrared and terahertz digital holography and their applications
Georges, Marc ULiege

Scientific conference (2017, October 03)

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See detailDeformation measurements by ESPI of the surface of a heated mirror and comparison with numerical model
Languy, Fabian ULiege; Vandenrijt, Jean-François ULiege; Saint-Georges, Philippe et al

in Proceedings of SPIE : The International Society for Optical Engineering (2017, June 26), 103291M

The manufacture of mirrors for space application is expensive and the requirements on the optical performance increase over years. To achieve higher performance, larger mirrors are manufactured but the ... [more ▼]

The manufacture of mirrors for space application is expensive and the requirements on the optical performance increase over years. To achieve higher performance, larger mirrors are manufactured but the larger the mirror the higher the sensitivity to temperature variation and therefore the higher the degradation of optical performances. To avoid the use of an expensive thermal regulation, we need to develop tools able to predict how optics behaves with thermal constraints. This paper presents the comparison between experimental surface mirror deformation and theoretical results from a multiphysics model. The local displacements of the mirror surface have been measured with the use of electronic speckle pattern interferometry (ESPI) and the deformation itself has been calculated by subtracting the rigid body motion. After validation of the mechanical model, experimental and numerical wave front errors are compared. [less ▲]

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See detailNondestructive inspection of aerospace composites by a fiber-coupled laser ultrasonics system
Vandenrijt, Jean-François ULiege; Languy, Fabian ULiege; Thizy, Cédric ULiege et al

in Proceedings of SPIE : The International Society for Optical Engineering (2017, June)

Laser ultrasonics is a technique currently studied for nondestructive inspection of aerospace composite structures based on carbon fibers. It combines a pulsed laser impacting the surface generates an ... [more ▼]

Laser ultrasonics is a technique currently studied for nondestructive inspection of aerospace composite structures based on carbon fibers. It combines a pulsed laser impacting the surface generates an ultrasound inside the material, through the nondestructive thermoelastic effect. Second a detection interferometer probes the impacted point in order to measure the displacement of the surface resulting from the emitted ultrasound wave and the echo coming back from the different interfaces of the structure. Laser ultrasonics is of interest for inspecting complex shaped composites. We have studied the possibility of using frequency doubled YAG laser for the generation and which is fiber-coupled, together with a fiber-coupled interferometric probe using a YAG laser in the NIR. Our final system is a lightweight probe attached to a robot arm and which is able to scan complex shapes. The performances of the system are compared for different wavelengths of generations. Also we have studied some experimental parameters of interest such as tolerance to angle and focus distance, and different geometries of generation beams. We show some examples of inspection of reference parts with known defects. In particular C-scans of curved composites structures are presented. [less ▲]

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See detailAccuracy improvement in digital holographic-based speckle correlation for three-dimensional (3D) displacement measurement
Zhao, Yuchen ULiege; Zemmamouche, Redouane; Vandenrijt, Jean-François ULiege et al

in Digital Holography and Three-Dimensional Imaging (2017, June)

Combination of digital holography and speckle correlation for three-dimensional displacement measurement suffers from inaccuracy. Speckle size adjustment and phase error correction during the digital ... [more ▼]

Combination of digital holography and speckle correlation for three-dimensional displacement measurement suffers from inaccuracy. Speckle size adjustment and phase error correction during the digital holography process can improve the accuracy of in-plane displacement measurement. [less ▲]

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See detailArtificial defects in CFRP composite structure for Thermography and Shearography nondestructive inspection
Blain, Pascal ULiege; Vandenrijt, Jean-François ULiege; Languy, Fabian ULiege et al

in Proc. SPIE 10449, Fifth International Conference on Optical and Photonics Engineering (2017, April)

Locating defects in CFRP composite materials is a hot topic in nondestructive inspection (NDI). Beside classical NDI technique, such as ultrasound testing (UT), contactless techniques are actively studied ... [more ▼]

Locating defects in CFRP composite materials is a hot topic in nondestructive inspection (NDI). Beside classical NDI technique, such as ultrasound testing (UT), contactless techniques are actively studied. Generally manufacturers of CFRP structure incorporate artificial defects in the bulk, with different extents and depths, in order to study the performance of a specific NDI technique to detect the defect. One of the most common defects in CFRP is delamination between two layers. This is simulated by inserting teflon sheets which, like air, acts as ultrasound blocker in UT. When such reference part is used to assess NDI performance of thermography or shearography, we only observe respectively the thermal or mechanical response of teflon with respect to external loading used with these techniques. In this work, we assess other possibilities for artificial defects in CFRP matrix. For that a CFRP structure was developed and which incorporates teflon, flat-bottom holes and delamination obtained by the pull-out method. We experimentally studied the signals and we discuss the difference between the various artificial defects methods. [less ▲]

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See detailContrôle non destructif champ complet. Techniques et applications
Georges, Marc ULiege

Learning material (2017)

Ce cours a été donné lors de la journée de formation préliminaire au Colloque Francophone CMOI-FLUVISU de la Société Française d'Optique (SFO). Il s'adresse aux étudiants et chercheurs souhaitant une mise ... [more ▼]

Ce cours a été donné lors de la journée de formation préliminaire au Colloque Francophone CMOI-FLUVISU de la Société Française d'Optique (SFO). Il s'adresse aux étudiants et chercheurs souhaitant une mise à niveau avant d'assister au colloque. Le cours traite du controle non destructif par techniques optiques sans contact et champ complet, en vue de la mesure de déformation, la détection de défauts, la caractérisation non destructive des matériaux. [less ▲]

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See detailUltrasons par laser pour l'inspection de matériaux composites. Comparaison entre génération à 532 nm et 10,6 µm. Effet de la géométrie du faisceau de génération
Vandenrijt, Jean-François ULiege; Languy, Fabian ULiege; Walter, Julien et al

Conference (2017, March)

Un système de contrôle non destructif basé sur la génération d'ultrasons par laser à 532 nm et de détection par laser, entièrement fibré et robotisé, est développé au CSL. Nous le comparons à un système ... [more ▼]

Un système de contrôle non destructif basé sur la génération d'ultrasons par laser à 532 nm et de détection par laser, entièrement fibré et robotisé, est développé au CSL. Nous le comparons à un système équivalent du CTA basé sur la génération plus classique avec un laser CO2 (10,6 µm). De plus nous montrons les résultats d'investigations concernant différentes géométrie du faisceau de génération. [less ▲]

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See detailInterférométrie de speckle à 10.6 µm et shearographie à 532 nm en temps réel temps moyenné et décalage de phase. Comparaison et application pour identification des modes de vibrations sur shaker industriel
Vandenrijt, Jean-François ULiege; Languy, Fabian ULiege; Thizy, Cédric ULiege et al

Conference (2017, March)

Deux méthodes interférométriques sont comparées pour l'identification des modes de vibration en temps réel-temps moyenné avec décalage de phase. Il s'agit d'une part de l'interférométrie de speckle (ESPI ... [more ▼]

Deux méthodes interférométriques sont comparées pour l'identification des modes de vibration en temps réel-temps moyenné avec décalage de phase. Il s'agit d'une part de l'interférométrie de speckle (ESPI) à 10,6 μm et, d'autre part, de la shearographie à 532 nm. La comparaison sur une aube de vibration en laboratoire nous a conduit à sélectionner la shearographie en lumière visible pour l'application avec un shaker en milieu industriel, où les conditions de travail ne permettent pas d'utiliser des techniques interférométriques plus conventionnelles. [less ▲]

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See detailAccuracy concerns in digital speckle photography combined with Fresnel digital holographic interferometry
Zhao, Yuchen ULiege; Zemmamouche, Redouane; Vandenrijt, Jean-François ULiege et al

in Optics and Lasers in Engineering (2017)

A combination of digital holographic interferometry (DHI) and digital speckle photography (DSP) allows in-plane and out-of-plane displacement measurement between two states of an object. The former can be ... [more ▼]

A combination of digital holographic interferometry (DHI) and digital speckle photography (DSP) allows in-plane and out-of-plane displacement measurement between two states of an object. The former can be determined by correlating the two speckle patterns whereas the latter is given by the phase difference obtained from DHI. We show that the amplitude of numerically reconstructed object wavefront obtained from Fresnel in-line digital holography (DH), in combination with phase shifting techniques, can be used as speckle patterns in DSP. The accuracy of in-plane measurement is improved after correcting the phase errors induced by reference wave during reconstruction process. Furthermore, unlike conventional imaging system, Fresnel DH offers the possibility to resize the pixel size of speckle patterns situated on the reconstruction plane under the same optical configuration simply by zero-padding the hologram. The flexibility of speckle size adjustment in Fresnel DH ensures the accuracy of estimation result using DSP. [less ▲]

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See detailLaser optics in space failure risk due to laser induced contamination
Kokkinos, Dimitrios ULiege; Schroeder, Helmut; Fleury-Frenette, Karl ULiege et al

in CEAS Space Journal (2017), 8

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See detailDigital holographic interferometry in the long-wave infrared and temporal phase unwrapping for measuring large deformations and rigid body motions of segmented space detector in cryogenic test (invited paper)
Vandenrijt, Jean-François ULiege; Thizy, Cédric ULiege; Martin, Laurent et al

in Optical Engineering: the Journal of the Society of Photo-Optical Instrumentation Engineers (2016), 55(12), 121723

We present digital holographic interferometry in the long-wave infrared for monitoring the deformation under cryogenic conditions of a segmented focal plane array (FPA) to be used in a space mission. The ... [more ▼]

We present digital holographic interferometry in the long-wave infrared for monitoring the deformation under cryogenic conditions of a segmented focal plane array (FPA) to be used in a space mission. The long wavelength was chosen for its ability to allow measurement of displacements 20 times larger than DHI in the visible and which were foreseen with the test object under large temperature variations. The latter is a mosaic of 4×4 detectors assembled on a frame. DHI was required to assess the global deformation of the assembly, the deformation of each detector, and piston movements of each of them with respect to their neighbors. For that reason we incorporated the temporal phase unwrapping by capturing a sufficiently high number of holograms between which the phase does not undergo large variations. At last, since the specimen exhibits specular reflectivity at that wavelength, it is illuminated by means of a reflective diffuser. [less ▲]

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See detailSpeckle Metrology
Mendoza Santoyo, Fernando; Georges, Marc ULiege; Lehmann, Peter et al

in Optical Engineering: the Journal of the Society of Photo-Optical Instrumentation Engineers (2016), 55(12), 121701

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See detailNon-contact emerging nondestructive techniques for aerospace composite inspection
Georges, Marc ULiege

Scientific conference (2016, November 17)

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See detailL'optique spatiale en Wallonie: de la génèse aux développements récents
Georges, Marc ULiege; Denis, Stefan; Joannes, Luc

Scientific conference (2016, November 10)

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