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See detailHolographic Filter applied to LCD projector for improvement of laser pointer presentation
Habraken, Serge ULg; Moreau, Vincent; Vandormael, Denis et al

in Proceedings of Spie (2000), 3951

Detailed reference viewed: 25 (6 ULg)
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See detailHolographic interferometers based on photorefractive crystals for vibration measurements
Georges, Marc ULg; Thizy, Cédric ULg; Ryhon, Sébastien et al

Conference (2002, June)

Photorefractive crystals offer many advantages over other classical holographic recording media. They allow fast in-situ processable holographic recording as well as indefinite reusability. Moreover high ... [more ▼]

Photorefractive crystals offer many advantages over other classical holographic recording media. They allow fast in-situ processable holographic recording as well as indefinite reusability. Moreover high signal-to-noise ratio can be reached as well as high resolutions. We present several types of holographic instruments using such materials. Here we will emphasize their applications in vibration measurements. A first one is based on the classical stroboscopic technique, a second one uses a pulsed laser. [less ▲]

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See detailHolographic interferometry based on photorefractive crystal to measure 3D thermo-elastic distortion of composite structures and comparison with finite element models
Thizy, Cédric ULg; Eliot, F.; Olympio, K.R. et al

in Lehmann, Peter (Ed.) Proc. SPIE Vol 8788 on Optical Measurement Systems for Industrial Inspection VIII (2013, May)

Thermo-elastic distortions of composite structures have been measured by a holographic camera using a BSO photorefractive crystal as the recording medium. The first test campaign (Phase 1) was performed ... [more ▼]

Thermo-elastic distortions of composite structures have been measured by a holographic camera using a BSO photorefractive crystal as the recording medium. The first test campaign (Phase 1) was performed on CFRP struts with titanium end-fittings glued to the tips of the strut. The samples were placed in a vacuum chamber. The holographic camera was located outside the chamber and configured with two illuminations to measure the relative out-of-plane and in-plane (in one direction) displacements. The second test campaign (Phase 2) was performed on a structure composed of a large Silicon Carbide base plate supported by 3 GFRP struts with glued Titanium end-fittings. Thermo-elastic distortions have been measured with the same holographic camera used in phase 1, but four illuminations, instead of two, have been used to provide the three components of displacement. This technique was specially developed and validated during the phase 2 in CSL laboratory. The system has been designed to measure an object size of typically 250x250 mm²; the measurement range is such that the sum of the largest relative displacements in the three measurement directions is maximum 20 μm. The validation of the four-illuminations technique led to measurement uncertainties of 120 nm for the relative in-plane and out-of-plane displacements, 230 nm for the absolute in-plane displacement and 400 nm for the absolute out-of-plane displacement. For both campaigns, the test results have been compared to the predictions obtained by finite element analyses and the correlation of these results was good [less ▲]

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See detailHolographic interferometry using photorefractive crystals for quantitative phase measurement on large objects
Georges, Marc ULg; Lemaire, Philippe ULg

in Benton, Stephen (Ed.) Practical Holography X (1996, January)

We recently have presented a real-time holographic interferometer using sillenite crystals connected with phase-shifting for quantitative measurement of diffuse objects deformations. In our basic set-up ... [more ▼]

We recently have presented a real-time holographic interferometer using sillenite crystals connected with phase-shifting for quantitative measurement of diffuse objects deformations. In our basic set-up, the crystal, sandwiched between two polarizers, is set in front of the optical head and followed by a CCD camera with an imaging objective. With this system, for conventional objects and using 2.2 Watts of Ar3+ laser power @ 514 nm, interferograms can be observed on object fields of about 30 cm*20 cm (crystal size 1 cm*1 cm and 26 mm objective focal length). In this paper we present investigations to increase the observed field in the existing system and to be able to use lower power lasers. Since setting the object at larger distances should lead to an insufficient luminous level for hologram recording, we have proceeded by different ways. First, we use shorter focal length objectives, giving a larger field-of-view, and larger crystals have to be used in this case to avoid vignetting. Second, we use a large aperture frontal objective in order to collect more light and that images the object on the crystal, the final image being observed through relay imagery. [less ▲]

Detailed reference viewed: 13 (6 ULg)
See detailHolographic interferometry using photorefractive crystals: recent advances and applications
Georges, Marc ULg; Lemaire, Philippe ULg

in Gorecki, Christophe (Ed.) Optical Inspection and Micromeasurements (1996, June)

We present a real-time holographic interferometer using sillenite crystals for measurement of deformations of large diffusive objects. Two kind of optical heads have been investigated: a first system with ... [more ▼]

We present a real-time holographic interferometer using sillenite crystals for measurement of deformations of large diffusive objects. Two kind of optical heads have been investigated: a first system with a frontal crystal followed by a CCD camera with a short focal length objective, and a second system with imaging objective in front of the crystal, collecting light and imaging the object in its vicinity, the final image being observed with a second relay imagery. Both systems art compared with respect to their temporal behaviour and quality of interferograms. This interferometer is connected with quantitative phase-measurement systems. First, phase-shifting (PS) can be performed by translating a mirror in the reference beam, enabling acquisition of several interferograms subsequently processed leading to the object phase deformation. Nevertheless this requires stability of the object during the shifting process. Second, Fourier transform (FT) processing can be used on a single interferogram. This interferometer has been successively used in different applications: detection of defects in weakly disturbed structures using PS and monitoring of thermal deformation of an object with FT processing. [less ▲]

Detailed reference viewed: 4 (1 ULg)
See detailHolographic interferometry using two-wavelength holography for the measurement of large deformations
Ninane, Nathalie ULg; Georges, Marc ULg

in Sirohi, R.; Hinsch, K. (Eds.) Selected papers on Holographic interferometry : Principles and technique (1998)

Detailed reference viewed: 19 (0 ULg)
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See detailHolographic interferometry with a 90 degrees photorefractive crystal geometry
Georges, Marc ULg; Pauliat, G.; Weidner, E. et al

in Delaye, Ph; Denz, C.; Mager, L. (Eds.) Photorefractive Effects, Materials, and Devices (2003, June)

Holographic interferometers are generally designed in the common geometry where both interfering waves (reference and object) enter the crystal by the same window (co-propagating configuration). The ... [more ▼]

Holographic interferometers are generally designed in the common geometry where both interfering waves (reference and object) enter the crystal by the same window (co-propagating configuration). The alternative presented here consists in using a reference beam entering the crystal by a lateral face. The crystal has to be cut adequately in order to obtain electro-optic properties similar to that of the co-propagating configuration but with a smaller optical scattering noise. Therefore higher signal-to-noise ratios are expected in the interferograms. We will present the main features and constraints of this configuration together with the experimental study of its noise characteristics. This work has been performed for sillenite and semiconductor crystals [less ▲]

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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 ▲]

Detailed reference viewed: 62 (1 ULg)
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See detailHolographic interferometry with photorefractive crystals. Early experiments and results of the ongoing european project PHIFE
Georges, Marc ULg; Thizy, Cédric ULg; Lemaire, Philippe et al

in Dantec Ettemeyer 11th International User Meeting (2004, October)

Photorefractive crystals offer many advantages over other classical holographic recording media. They allow fast in-situ processable holographic recording as well as indefinite reusability. Moreover high ... [more ▼]

Photorefractive crystals offer many advantages over other classical holographic recording media. They allow fast in-situ processable holographic recording as well as indefinite reusability. Moreover high signal-to-noise ratio can be reached as well as high resolutions. We present several types of holographic instruments using such materials. Here we will emphasize their applications in vibration measurements. A first one is based on the classical stroboscopic technique, a second one uses a pulsed laser. We describe also the recent results obtained in the framework of the european project PHIFE (Pulsed Holographic Interferomete for the analysis of Fast Events), aiming at developing a full field measurement system of vibrations modes at high repetition rate. [less ▲]

Detailed reference viewed: 24 (1 ULg)
Peer Reviewed
See detailHolographic optical elements
Stijns, Erik; Roose, Stéphane ULg

in Haris, D.; Shay, T. (Eds.) Proceedings of the international conference Lasers '89 (1989)

Detailed reference viewed: 14 (3 ULg)
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See detailHolographic photorefractive images storage for applied metrology by interferometry
Lemaire, Philippe ULg; Georges, Marc ULg

in Lagarde, A. (Ed.) Advanced Optical Methods and Applications in Solid Mechanics (2000)

Detailed reference viewed: 4 (0 ULg)
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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 ▲]

Detailed reference viewed: 37 (7 ULg)
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See detailHoly Motherhood: Gender, Dynasty and Visual Culture in the Later Middle Ages
L'Estrange, Elizabeth ULg

Book published by Manchester University Press (2008)

This book brings images of holy motherhood and childbearing into the centre of an art-historical enquiry. By focusing on images of St Anne and the Holy Kinship in Books of Hours made for aristocratic ... [more ▼]

This book brings images of holy motherhood and childbearing into the centre of an art-historical enquiry. By focusing on images of St Anne and the Holy Kinship in Books of Hours made for aristocratic women in relation to the dynastic importance of heirs, it reassesses the role of the female viewer as an active agent in the interpretation of pictures and popular devotional rites. Holy motherhood combines an innovative methodology that draws on art-historical and contemporary gender studies with empirical evidence from fifteenth-century manuscripts, to show how images worked not only to script and maintain gender and social roles within patriarchal society but also to offer viewers ways of managing those roles. Some of the manuscripts discussed are relatively unknown and their images and texts are made available to readers for the first time. The study begins by problematising the notion that intimate, post-partum images of holy childbirth found in Books of Hours provide a window onto the medieval past and women's viewing habits. Through an adaptation of Baxadall's 'period eye', the first part of the book explores how aristocratic lay women - and men - viewed and interpreted images of childbirth by considering their familiarity with prayers for childbirth, the lying-in ceremony and the rite of churching. The second part uses this methodology to interpret the images and prayers in six bespoke manuscripts, including the Fitzwilliam Hours, owned by several Angevin and Breton duchesses, and the Hours of Marguerite of Foix. The book will appeal to advanced students, academics and researchers of Art History, Illuminated Manuscripts, Medieval History and Gender Studies. [less ▲]

Detailed reference viewed: 357 (14 ULg)
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See detailHombre de letras, escritor, autor: declinación social de una función simbólica
Durand, Pascal ULg

in Zapata, Juan (Ed.) La invención del autor. Nuevas aproximaciones al estudio sociológico y discursivo de la figura autorial (2014)

EL LIBRO El presente volumen pretende introducir en el ámbito hispanoamericano las nuevas aproximaciones teóricas y las diferentes apuestas metodológicas surgidas durante las dos últimas décadas para ... [more ▼]

EL LIBRO El presente volumen pretende introducir en el ámbito hispanoamericano las nuevas aproximaciones teóricas y las diferentes apuestas metodológicas surgidas durante las dos últimas décadas para abordar el estudio de la figura del autor y el problema de la autorialidad. Desde el desafío lanzado por Michel Foucault en su ensayo "¿Qué es un autor?", y que encabeza esta compilación, se han producido distintas respuestas y elaboraciones por parte de un grupo de investigadores que provienen de coordenadas geográficas tan diversas como Francia, Bélgica, Suiza, Canadá e Israel. Estos son los escritores que integran en su mayor parte esta compilación, con temas como la historia de la figura autorial, la imagen y la postura de autor, y el dilema y los mitos del autor moderno; además, el texto ofrece aplicaciones concretas, tanto desde una perspectiva europea (mediante el estudio de autores como Arthur Rimbaud, Gide, Pierre Michon y Jean Rouaud) como desde una colombiana (con análisis sobre José Asunción Silva, Jorge Gaitán Durán, Fernando Vallejo y Efraim Medina Reyes). La invención del autor permite conocer los desarrollos más actuales y destacados en la materia, y abre numerosos ejes de investigación en una temática especialmente importante y sensible en la actualidad, pero sobre la cual se ha publicado muy poco en nuestro medio; de ahí la importancia de esta antología para el debate académico. [less ▲]

Detailed reference viewed: 49 (7 ULg)