References of "Thizy, Cédric"
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See detailPhotoelectric Conversion Effect in Non-Photovoltaic Photorefractive Materials
Frejlich, Jaime; De Oliveira, Ivan; Carvalho, Jesiel et al

in Latin America Optics & Photonics Conference (LAOP) - OSA Technical Digest (online) (2014, November)

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See detailCombined holography and thermography in a single sensor through image-plane holography at thermal infrared wavelengths
Georges, Marc ULg; Vandenrijt, Jean-François ULg; Thizy, Cédric ULg et al

in Optics Express (2014), 22(21), 25517-25529

Holographic interferometry in the thermal wavelengths range, combining a CO2 laser and digital hologram recording with a microbolometer array based camera, allows simultaneously capturing temperature and ... [more ▼]

Holographic interferometry in the thermal wavelengths range, combining a CO2 laser and digital hologram recording with a microbolometer array based camera, allows simultaneously capturing temperature and surface shape information about objects. This is due to the fact that the holograms are affected by the thermal background emitted by objects at room temperature. We explain the setup and the processing of data which allows decoupling the two types of information. This natural data fusion can be advantageously used in a variety of nondestructive testing applications. [less ▲]

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See detailVibration analysis by speckle interferometry with CO2 lasers and microbolometers arrays
Vandenrijt, Jean-François ULg; Thizy, Cédric ULg; Georges, Marc ULg

in Imaging and Applied Optics 2014, OSA Technical Digest (online) (2014, July)

Speckle interferometry in the time-average mode in long wave infrared is shown for observing the mode shapes of vibrating objects. The long wavelength allows observing larger vibration displacements than ... [more ▼]

Speckle interferometry in the time-average mode in long wave infrared is shown for observing the mode shapes of vibrating objects. The long wavelength allows observing larger vibration displacements than what is achieved with visible wavelengths. [less ▲]

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See detailLong-wave infrared digital holographic interferometry with diffuser or point source illuminations for measuring deformations of aspheric mirrors
Vandenrijt, Jean-François ULg; Thizy, Cédric ULg; Queeckers, Patrick et al

in Optical Engineering : The Journal of the Society of Photo-Optical Instrumentation Engineers (2014), 53(11), 112309

Long-wave infrared digital holographic interferometry with CO2 laser and microbolometer arrays has been developed for testing the large deformations of space reflectors. The setup considered is a ... [more ▼]

Long-wave infrared digital holographic interferometry with CO2 laser and microbolometer arrays has been developed for testing the large deformations of space reflectors. The setup considered is a Mach–Zehnder, associated to the digital holography reconstruction of the wavefront in the inline configuration with phase shifting. Two possibilities exist for illuminating the tested reflector: either with a point source (similarly to classical interferometry) or an extended source (with a diffuser). This paper presents the development of a modular setup which allows comparing both in the case of a parabolic mirror [less ▲]

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See detailSimultaneous Temperature and Deformations Measurements Using Long-Wave Infrared Speckle Interferometry: A Novel Hybrid Technique for Industrial Nondestructive Testing
Georges, Marc ULg; Vandenrijt, Jean-François ULg; Thizy, Cédric ULg et al

in Osten, Wolfgang (Ed.) Fringe 2013 (2014)

The use of long-wave infrared (LWIR) CO2 lasers and microbolometer arrays in digital holographic and speckle interferometry shows interesting features for full-field displacement/deformation metrology and ... [more ▼]

The use of long-wave infrared (LWIR) CO2 lasers and microbolometer arrays in digital holographic and speckle interferometry shows interesting features for full-field displacement/deformation metrology and nondestructive testing. The first one is that the long wavelength yields the measurement of larger displacements together with decreasing the sensitivity to environmental perturbations. Therefore these interferometric methods can be applied more easily in industrial field applications. Another advantage was put forward in the European project FANTOM which is presented in this paper. In addition to specklegrams, the thermal background is captured simultaneously. Therefore in displacement metrology one can correlate uniquely the temperature and displacement information at the same time and in each pixel. We describe the successful achievements of the project. Thorough understanding of optics and speckle interferometry crossed with state-of-art in thermam imaging systems allowed to study this new hybrid technique in deep and tackle some specific constraints for reaching the best performances. As a result, a mobile instrument has been developed and validated on various industrial structural testing facilities and inspection areas. It has been used in thermomechanical measurements as well as in detection of defects in aeronautical composites. In particular we show that the two parts of the signal (the thermal part on one hand and the interferograms showing the deformation on the other hand) yield complementary information. A very interesting result is that it allows increasing the probability of detecting defects, for some of them are better seen in the thermal signal, whereas others appear only through local surface deformation. [less ▲]

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See detailDigital Holographic Interferometry in the Long-Wave Infrared for the Testing of Large Aspheric Space Reflectors
Vandenrijt, Jean-François ULg; Thizy, Cédric ULg; Stockman, Yvan ULg et al

in Osten, Wolfgang (Ed.) Fringe 2013 (2014)

Digital holographic (DH) interferometry has been developed in the long-wave infrared spectral range with CO2 lasers and microbolometer arrays. This application has been driven by the European Space ... [more ▼]

Digital holographic (DH) interferometry has been developed in the long-wave infrared spectral range with CO2 lasers and microbolometer arrays. This application has been driven by the European Space Agency’s constant need of techniques for monitoring large displacements of large structures. Here the study focuses on the case of aspheric mirrors, like parabola and ellipses. Usually they are tested through interferometric wavefront error measurements which require expensive null-lenses matching each of the reflectors considered. In the case of monitoring deformation a holographic technique can be considered where the wavefront is compared with itself at different instant. Therefore the optical can be quite simple and easily reconfigurable from one reflector to another. The advantage of using long wavelength is that large deformations can be measured at once, in addition to being more immune against environmental perturbations. Another advantage of DH at such wavelengths is that the ratio between the wavelength and the pixel size allows reconstructing objects 5 to 10 times larger than with DH in the visible. In this project we considered first the case of a 1.1 meter diameter parabola for submillimeter range observations. Such specimen shows strong specular reflectivity. We have developed several set-ups with different ways to illuminate the object and to collect rays to form the object beam: either through point source or through and extended diffuser working by reflection of the laser beam. Both possibilities have been compared in terms of fringe quality as well as measurement range. We selected the diffuser illumination for applying the set-up into a large vacuum facility for measuring the deformation of the parabola between 224 and 107 K. Results of this measurement campaign are presented. A further application has been shown by observation of off-axis ellipse. In this case interferometric testing is difficult to achieve and LWIR DHI with diffuser illumination is found quite simple to implement and gives straightforward results. [less ▲]

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See detailComparaison de techniques CND émergentes sur des pièces aéronautiques en matériaux composites
Georges, Marc ULg; Thizy, Cédric ULg; Lewandowski, Jacques et al

Conference (2013, November)

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See detailMobile speckle interferometer in the long-wave infrared for aeronautical nondestructive testing in field conditions
Vandenrijt, Jean-François ULg; Thizy, Cédric ULg; Alexeenko, Igor et al

in Optical Engineering : The Journal of the Society of Photo-Optical Instrumentation Engineers (2013), 52(10),

Abstract We present the development of a speckle interferometer based on CO2 laser and using a thermal infrared camera based on uncooled microbolometer array. It is intended to be used for monitoring ... [more ▼]

Abstract We present the development of a speckle interferometer based on CO2 laser and using a thermal infrared camera based on uncooled microbolometer array. It is intended to be used for monitoring deformations as well as flaw detection in aeronautical composites, with a smaller sensitivity to displacement compared to equivalent system using visible lasers. Moreover the long wavelength allows working with such interferometer under out-of-laboratory conditions. A mobile system has been developed on the basis of previous laboratory developments. Then it is validated in a variety of industrial nondestructive testing applications under field working conditions. [less ▲]

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See detailDigital Holographic Interferometry with CO2 Lasers Applied to Aspheric Space Reflectors Testing
Georges, Marc ULg; Vandenrijt, Jean-François ULg; Thizy, Cédric ULg et al

in Digital Holography and Three-Dimensional Imaging, OSA Technical Digest (online) (2013, May)

Digital holographic interferometry at long infrared wavelengths allows monitoring large deformations of space reflectors during vacuum-thermal testing. We present different optical schemes and an ... [more ▼]

Digital holographic interferometry at long infrared wavelengths allows monitoring large deformations of space reflectors during vacuum-thermal testing. We present different optical schemes and an application to the complex case of elliptic reflector. [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 detailNondestructive testing by using long wave infrared interferometric techniques with CO2 lasers and microbolometer arrays
Alexeenko, Igor; Vandenrijt, Jean-François ULg; Pedrini, Giancarlo et al

in Applied Optics (2013), 52(1), 57-67

We describe three different interferometric techniques (electronic speckle pattern interferometry, digital holographic interferometry, digital shearography), using a long wave infrared radiation produced ... [more ▼]

We describe three different interferometric techniques (electronic speckle pattern interferometry, digital holographic interferometry, digital shearography), using a long wave infrared radiation produced by a CO2 laser and recording on a microbolometers array. Experimental results showing how these methods can be used for nondestructive testing are presented. Advantages and disadvantages of these approaches are discussed. [less ▲]

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See detailDigital holographic interferometry with CO2 lasers and diffuse illumination applied to large space reflectors metrology
Georges, Marc ULg; Vandenrijt, Jean-François ULg; Thizy, Cédric ULg et al

in Applied Optics (2013), 52(1), 102-116

Digital holographic interferometry in the long wave infrared domain has been developed by combining a CO2 laser and a microbolometer array. The long wavelength allows large deformation measurements which ... [more ▼]

Digital holographic interferometry in the long wave infrared domain has been developed by combining a CO2 laser and a microbolometer array. The long wavelength allows large deformation measurements which are of interest in the case of large space reflectors undergoing thermal changes when in orbit. We review holography at such wavelengths and present some specific aspects related to this spectral range on our measurements. For the design of our digital holographic interferometer we studied the possibility of illuminating specular objects by a reflective diffuser. We discuss the development of the interferometer and the results obtained on a representative space reflector, first in the laboratory and then during vacuum cryogenic test. [less ▲]

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See detailLong-wave infrared digital holography for the qualification of large space reflectors
Vandenrijt, Jean-François ULg; Thizy, Cédric ULg; Georges, Marc ULg et al

Conference (2012, October 09)

Deformation metrology of complex and large space reflectors is a recurrent problem addressed by ESA. The challenging tasks of on-ground qualification and verification testing are to achieve the required ... [more ▼]

Deformation metrology of complex and large space reflectors is a recurrent problem addressed by ESA. The challenging tasks of on-ground qualification and verification testing are to achieve the required accuracy in the measurement of these reflectors deformation and to verify their performance under simulated space conditions (vacuum, low temperature). A long-wave infrared digital holographic interferometer for the verification and validation of this type of reflector in a space environment is presented. It has been developed to fill the gap between holography/interferometry techniques in the visible wavelengths and methods based on structured light illumination like videogrammetry, stereocorrelation, and fringe/pattern projection. The former provide a good measurement uncertainty but the displacements are often too large to be measured and they require a very stable environment, while the latter provide large measurement range but with higher measurement uncertainty. The new instrument is based on digital holography and uses a CO2 lasers emitting at 10.6 µm combined with a commercial thermographic camera. A diffuser is illuminated by the laser beam, producing a speckle wavefront which is observed after reflection on the reflector surface. This reflected speckle wavefront behaves exactly as if the reflector was a diffusive surface, producing its own speckle, allowing the measurement of its deformation. The advantage of this configuration compared to a classical interferometer working at 10.6 µm, is that it requires no specific optics such as a null lens (in the case of parabola) or expensive illumination/collection optics (in the case of ellipse). The metrological certification of the system was performed in the laboratory by measuring the tilts of a 1.1 meter diameter parabolic reflector. The displacements are measured in parallel with a Doppler effect interferometer and the measurement uncertainty is estimated. The application of the new interferometer to the measurement of an elliptic reflector is also presented. The technique has been certified during a thermal-vacuum test. The deformation of the parabolic reflector is measured for a temperature variation from 288 K down to 113 K. The results are compared to previous results obtained on the same reflector with a high spatial resolution infrared interferometer, also developed at CSL. [less ▲]

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See detailSpeckle interferometry at 10 µm with CO2 lasers and microbolometers array
Georges, Marc ULg; Vandenrijt, Jean-François ULg; Thizy, Cédric ULg et al

in Kieffer, Jean-Claude (Ed.) Photonics North 2012 (2012, June 06)

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See detailDigital Holographic Interferometry and ESPI at Long Infrared Wavelengths with CO2 Laser (invited paper)
Georges, Marc ULg; Vandenrijt, Jean-François ULg; Thizy, Cédric ULg et al

in Digital Holography and 3D Imaging (DH2012) (2012, April 28)

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See detail3D thermo-elastic distortion measurements on OSIRIS SiC hardware by holographic interferometry and correlation with finite element models
Thizy, Cédric ULg; Eliot, Fabienne; Ballhause, Dirk et al

Conference (2012, March)

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