References of "Georges, Marc"
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See detailDisplacement measurements of a parabolic reflector by holographic interferometry in the long-wavelength infrared
Vandenrijt, Jean-François ULg; Georges, Marc ULg; Thizy, Cédric ULg et al

in International Astronautical Congress 2010 (2010, September)

Deformation metrology of complex shape space structure and reflectors is a recurrent problem addressed by ESA. Consequently, suitable measurement techniques have to be developed and validated to support ... [more ▼]

Deformation metrology of complex shape space structure and reflectors is a recurrent problem addressed by ESA. Consequently, suitable measurement techniques have to be developed and validated to support relevant on-ground qualification and verification testing. Holographic techniques in the visible wavelengths are common for measuring the surface displacement of object. However the short wavelength induces high stability criteria which are so severe that they often prevent the measurement of large space structures under good conditions. We propose to use a wavelength longer than the usual visible ones to render such holographic displacement measurement techniques less sensitive to external perturbations. For this we consider CO2 laser emitting at 10.6 μm which correspond to the long-wavelength infrared (LWIR) spectrum. The most important element for performing holography is to use an adequate recording medium. However no convincing holographic recording media exists in LWIR and we decided to investigate the possibility of electronic hologram recording, such as electronic speckle pattern interferometry (ESPI). This possibility is feasible nowadays thanks to various thermal imaging technologies such has uncooled microbolometers sensors commonly found in thermographic cameras. In this study, we analyse how it is possible to measure surface displacements of specular objects, which do not produce speckle, using speckle interferometry by the mean of a scattering diffuser. We then apply the ESPI technique at LWIR for measuring displacements of a large parabolic reflector. [less ▲]

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See detailDigital holographic interferometry by using long infrared radiation (CO2 laser)
Alexeenko, Igor; Vandenrijt, Jean-François ULg; Georges, Marc ULg et al

in Advances in Experimental Mechanics VII (2010, September)

We show how digital holographic interferometry in the Long Wave InfraRed (LWIR) spectral range can be used for the investigation of mechanical structures. The 10.6 μm radiation is produced by a CO2 Laser ... [more ▼]

We show how digital holographic interferometry in the Long Wave InfraRed (LWIR) spectral range can be used for the investigation of mechanical structures. The 10.6 μm radiation is produced by a CO2 Laser. Experimental results showing that the method can be used to locate defect in a panel are presented and advantages and disadvantages of this approach are discussed [less ▲]

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See detailTri automatique du verre: identification des impuretés par la méthode LIBS
Carapelle, Alain ULg; Georges, Marc ULg; Meekers, Sylvie et al

in Verre Science Technologie Industrie Produit Art Histoire (2009), 15(5), 29

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See detailAutomated Phase Map Referencing Against Historic Map Data
Groves, Roger; De Rauw, Dominique ULg; Thizy, Cédric ULg et al

in Osten, W.; Kujawinska, M. (Eds.) Fringe 2009 (2009, September)

Holography and shearography techniques are in common use for precise measurements in high technology industries, such as aerospace, automotive, precision manufacturing and for the structural diagnostics ... [more ▼]

Holography and shearography techniques are in common use for precise measurements in high technology industries, such as aerospace, automotive, precision manufacturing and for the structural diagnostics of artwork. The phase map data generated by these instruments allows precise measurements of parameters such as displacement, strain and shape. The comparison of data from different measurement campaigns is useful for null testing components and for studying changes. However, the comparison of data with previous measurements is non-trivial due to the sensitivity of these techniques to alignment and to sample loading parameters. This paper addresses image and phase registration issues for holography and shearography. This manuscript describes 2D spatial co-registration to compensate for differences between the field of view between the measurements and a phase referencing to calculate the difference between the phase maps. These techniques are implemented after following a standardised measurement procedure. [less ▲]

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See detailElectronic Speckle Pattern Interferometry at Long Infrared Wavelengths. Scattering Requirements
Vandenrijt, Jean-François ULg; Thizy, Cédric ULg; Alexeenko, Igor et al

in Osten, Wolfgang; Kujawinska, Malgorzata (Eds.) Fringe 2009 (2009, September)

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See detailDynamic holographic interferometry for dilatation measurements in vacuum-thermal conditions
Thizy, Cédric ULg; Barbier, Christian ULg; Barzin, Pascal ULg et al

in Lehmann, Peter (Ed.) Proc. SPIE Vol 7398 on Optical Measurement Systems for Industrial Inspection VI (2009, June)

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See detailDynamic holographic interferometry development for dilatometry measurement of composites under vacuum-thermal conditions
Thizy, Cédric ULg; Barbier, Christian ULg; Tychon, Isabelle ULg et al

in Dirckx, J.; Buytaert, J. (Eds.) Proceedings of the 4th International Conference on Optical Measurement and Techniques for Systems & Structures (OPTIMESS 2009) (2009)

The Centre Spatial de Liège develops since 1993 holographic interferometry techniques and instruments based on photorefractive crystals for high resolution measurement of structures deformation, mainly ... [more ▼]

The Centre Spatial de Liège develops since 1993 holographic interferometry techniques and instruments based on photorefractive crystals for high resolution measurement of structures deformation, mainly for aerospace applications. In this paper we present the early results of development of a holographic technique and facility for deformation and expansion measurement of aerospace composites components. Here the holographic technique consists in using several illumination beams for retrieving different components of the displacement vector. In our case the components and structures to be measured in the future will undergo temperatures excursions up to 150°C typically. Since holographic techniques are sensitive to air turbulences, it is necessary to place the samples in a vacuum chamber. We will present some early examples of measurements with this facility, obtained for temperatures excursions ranged between ambient and 29°C as first steps before going further to higher temperatures excursions. [less ▲]

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See detailCoherent metrology in impact assessment of movable artwork: the MULTIENCODE project
Tornari, V.; Bernikola, E.; Osten, W. et al

Conference (2008, November)

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See detailEtude de la technique LIBS en vue du tri des vitrocéramiques dans les déchets verriers
Georges, Marc ULg; Carapelle, Alain ULg; Mombaerts, Johan et al

Conference (2008, November)

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See detailInterférométrie holographique photoréfractive : nouveaux développements et applications récentes
Thizy, Cédric ULg; Georges, Marc ULg; Hustinx, Guy-Michel et al

Conference (2008, November)

Les cristaux photoréfractifs permettent l'enregistrement holographique dynamique in-situ et une réutilisabilité infinie. Aussi ils possèdent des propriétés spécifiques que d'autres matériaux ... [more ▼]

Les cristaux photoréfractifs permettent l'enregistrement holographique dynamique in-situ et une réutilisabilité infinie. Aussi ils possèdent des propriétés spécifiques que d'autres matériaux holographiques n'ont pas et qui peuvent être utilisées de manière avantageuse en interférométrie holographique. Depuis 15 ans, le CSL développe des techniques d'interférométrie holographique et des instruments basés sur des cristaux de Bi12SiO20 (BSO). Le comportement dynamique de ces derniers permet une grande souplesse d'utilisation de l'interférométrie holographique, à l'instar des techniques basées sur l'enregistrement numérique, tout en fournissant des interférogrammes de meilleure résolution que celles-ci (pas de bruit de speckle, pas de filtrage nécessaire). Par le passé, nous avons déjà présenté une large gamme d'applications en métrologie, contrôle non destructif et mesures vibratoires. Ici nous présentons des applications industrielles récentes obtenue avec une caméra holographique photoréfractive commercialisée. Cette dernière a été utilisée avec succès dans des applications très demandeuses, notamment en terme de résolution. [less ▲]

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See detailDefect growth in model panel paintings by full field interferometry
Kouloumpi, E.; Moutsatsou, A.; Torres, L. et al

Conference (2008, November)

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See detailRole of photorefractive holographic interferometry in Impact Assessment Procedure applied to movable cultural heritage
Thizy, Cédric ULg; De Rauw, Dominique ULg; Georges, Marc ULg et al

in Proceedings of the International Symposium to Commemorate the 60th Anniversary of the Invention of Holography (2008, October)

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See detailHolographic interferometry with photorefractive crystals : recent industrial applications
Thizy, Cédric ULg; Georges, Marc ULg; Hustinx, Guy-Michel et al

in Proceedings of the International Symposium to Commemorate the 60th Anniversary of the Invention of Holography (2008, October)

Photorefractive crystals allow in-situ dynamic holographic recording and indefinite reusability. Also they exhibit specific properties that other recording materials do not and which can be advantageously ... [more ▼]

Photorefractive crystals allow in-situ dynamic holographic recording and indefinite reusability. Also they exhibit specific properties that other recording materials do not and which can be advantageously used in holographic interferometry. For 15 years we have been developing holographic interferometry techniques and devices with Bi12SiO20 (BSO) crystals. The dynamic behaviour of the latter allows a high degree of userfriendliness of holographic interferometry (like techniques based on electronic recording), together with higher resolution interferograms (no speckle noise - no need of filtering). In the past we already have presented a wide range of applications in metrology, NDT and vibrations measurement. Here we present recent industrial applications obtained with a device which is now commercially available. It has proven successful applications in highly demanding applications where high resolution was required [less ▲]

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See detailHolographic techniques at long wave infrared wavelengths
Vandenrijt, Jean-François ULg; Georges, Marc ULg

in Proceedings of the International Symposium to Commemorate the 60th Anniversary of the Invention of Holography (2008, October)

For industrial applications, holographic interferometry and electronic speckle pattern interferometry techniques using visible laser light are often too sensitive to external perturbations. Consequently ... [more ▼]

For industrial applications, holographic interferometry and electronic speckle pattern interferometry techniques using visible laser light are often too sensitive to external perturbations. Consequently they require too much stability, preventing their widespread use in field applications. One simple idea to overcome this problem is to increase the wavelength of the laser light. We considered the 10 µm wavelength range corresponding to well known CO2 laser and because imagers exist in this spectral range. One other important advantage is that the strain/displacement measurement range is larger than the equivalent techniques in visible light. We will present the preliminary experiences performed so far with components available in our lab. Mainly, we show in-plane electronic speckle pattern interferometry and for the first time digital holographic interferometry. We also discuss specific problems related to the wavelength increase. [less ▲]

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See detailRewritable VPHGs based on photochromic materials
Bianco, A.; Toso, G.; Dassa, G. et al

in Attad-Ettedqui, A.; Lemke, D. (Eds.) Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation (2008, June)

Volume phase holographic gratings (VPHGs) are becoming an interesting alternative to the ruled gratings in modern astronomical instrumentation. Photochromic materials with thermal stability are good ... [more ▼]

Volume phase holographic gratings (VPHGs) are becoming an interesting alternative to the ruled gratings in modern astronomical instrumentation. Photochromic materials with thermal stability are good candidates for the development of holographic optical elements and in particular for VPHGs. VPHGs based on photochromic materials can be written and erased many times without the degradation of the material; moreover the material does not need any developing process after the exposure, making the writing process very simple. We have already studied photochromic materials for this aim in the framework of the JRA6 (Opticon Project, FP6) and we found that large modulations of the refractive index can be achieved using diarylethene polymers. Going from the materials characterization to technology, substrates with larger thickness and good optical properties are required. Herein we present the development of new technique to tailor the thickness of the photochromic films in two ranges: 5 - 30 micron and 700 - 1000 micron. The former are suitable for the development of broadband VPHGs, whereas the latter are suitable for narrow band tunable filters application. Details on the optical properties of the films are reported. Finally, a holographic set-up based on an Ar+ laser has been optimized in order to write the gratings. [less ▲]

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See detailInterférométrie de speckle en infrarouge thermique
Vandenrijt, Jean-François ULg; Georges, Marc ULg

in Résumés du Huitième colloque francophone Méthodes et Techniques Optiques pour l'Industrie (2007, November)

L’utilisation de l'interférométrie de speckle (ESPI) sur des objets opaques diffusants à une longueur d’onde de 10 µm en utilisant une caméra thermographique commerciale est présentée pour la première ... [more ▼]

L’utilisation de l'interférométrie de speckle (ESPI) sur des objets opaques diffusants à une longueur d’onde de 10 µm en utilisant une caméra thermographique commerciale est présentée pour la première fois à notre connaissance. L’idée d’utiliser une longueur d’onde plus grande que les longueurs d’onde visibles habituelles est de rendre les mesures de déplacements par des techniques holographiques moins sensibles aux perturbations extérieures. Dans cet article, nous discutons certains aspect particuliers dûs à l’accroissement de la longueur d’onde dans le domaine thermique de 10 µm. Nous montrons ensuite les résultats de mesures de rotations dans le plan d’une plaque métallique. Nous avons utilisé la technique du décalage de phase pour obtenir des mesures quantitatives qui sont corrélées par des mesures menées en parallèle avec un théodolite. [less ▲]

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See detailApplications with inorganic photorefractives: marketed systems and future potentialities
Georges, Marc ULg

Scientific conference (2007, October 19)

In his talk, Dr. Georges will present some applications using inorganic photorefractive materials that present potentialities in various fields. He will focus particularly on recent works that gave birth ... [more ▼]

In his talk, Dr. Georges will present some applications using inorganic photorefractive materials that present potentialities in various fields. He will focus particularly on recent works that gave birth to commercial systems and those that were granted "Best applications of photorefractive materials" in OSA sponsored or co-sponsored Topical Meetings on Photorefractive Effects, Materials and Devices like: - Holographic filtering in telecoms and laser mode filtering. - Dynamic hologram recording: laser ultrasound non-destructive testing. - Holographic interferometry for metrology and non-destructive testing. Dr. Georges will discuss the figures of merit of recording materials and try to initiate a debate for new application potentialities related to new photorefractive or photosensitive materials. [less ▲]

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See detailPhase control for the stabilization of a photorefractive holographic camera in perturbed environments
Thizy, Cédric ULg; Georges, Marc ULg; Lemaire, philippe

in Hesselink, Lambertus; Feinberg, Jack (Eds.) Controlling Light with Light: Photorefractive Effects, Photosensitivity, Fiber Gratings, Photonic Materials and More (2007, October)

The holographic interferometer developed by CSL, and which uses a BSO crystal, exhibits a response time of a few seconds. This prevents us to properly record holograms under perturbated environmental ... [more ▼]

The holographic interferometer developed by CSL, and which uses a BSO crystal, exhibits a response time of a few seconds. This prevents us to properly record holograms under perturbated environmental conditions due to optical phase variations between reference and object beams. We present hereafter several active phase control strategies to overcome this problem [less ▲]

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See detailPhotorefractive holographic interferometry for movable artwork assessment
Thizy, Cédric ULg; Georges, Marc ULg; Koulompi, Eleni et al

in Hesselink, Lambertus; Feinberg, Jack (Eds.) Controlling Light with Light: Photorefractive Effects, Photosensitivity, Fiber Gratings, Photonic Materials and More (PR07) (2007, October)

Photorefractive holographic interferometry is applied to assessment of movable cultural heritage. Its role is to observe tiny signatures resulting from internal artwork characteristics. In the future, the ... [more ▼]

Photorefractive holographic interferometry is applied to assessment of movable cultural heritage. Its role is to observe tiny signatures resulting from internal artwork characteristics. In the future, the system will be used for both antifraud and restoration [less ▲]

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