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

Poster (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 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 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 detailHolographie numérique en infrarouge lointain - Applications aérospatiales
Georges, Marc ULiege; Vandenrijt, Jean-François ULiege; Languy, Fabian ULiege et al

Conference (2016, November)

L'holographie numérique en infrarouge lointain, utilisant un laser CO2 émettant vers 10 µm et des caméras thermiques à microbolomètres, permet la mesure de grandes déformations et de s'affranchir des ... [more ▼]

L'holographie numérique en infrarouge lointain, utilisant un laser CO2 émettant vers 10 µm et des caméras thermiques à microbolomètres, permet la mesure de grandes déformations et de s'affranchir des perturbations environnementales plus facilement qu'en lumière visible. Nous l'appliquons dans le cas de structures spatiales subissant des cyclages thermiques en régime cryogénique sous vide, ce qui induit des déplacements de grande ampleur. Nous passerons en revue les différentes expériences effectuées au Centre Spatial de Liège et discuterons des recherches en cours, notamment pour utiliser des longueurs d'onde plus grande (ondes Terahertz) [less ▲]

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See detailLaser Ultrasound for NDT: investigation of the generation beam shape
Languy, Fabian ULiege; Perrard, Aurélie; Vandenrijt, Jean-François ULiege et al

Poster (2016, July)

Usually laser ultrasonic systems use an infrared laser operating at 10 µm to generate the ultrasound in CFRP objects. However this system suffer from an important drawback: optical fiber cannot be used to ... [more ▼]

Usually laser ultrasonic systems use an infrared laser operating at 10 µm to generate the ultrasound in CFRP objects. However this system suffer from an important drawback: optical fiber cannot be used to transport the high energy beam from the laser output to the target which limits the flexibility of the system to investigated complex shaped objects. To overcome this issue, visible light can be used to generate ultrasound. In our case we use a fiber-coupled laser operating at 532 nm. The output end of the optical fiber is placed on an industrial robot arm. The investigated object remains stationary while the optical fiber mounted on the robot arm scan the object. This system offers large flexibility but laser generation at 532 nm is known to be less efficient than CO 2 system emitting at 10 µm. Increasing the visible pulse power is one of the options but optics and CRFF object will be damaged before the same echo level as CO2 generation can be obtained. An alternative solution consists in the investigation of the generation beam size and shape. We recently developed an optical design composed of an axicon lens able to generate annular beam. The diameter of the beam can be adapted. If the axicon lens is removed the optical system provides a disk whose diameter can also be adapted onto the investigated object. Ray-traycing simulations performed with ASAP and experimental beam profile investigated with a beam profiler show good agreement between theoretical and experimental optical design. An experimental comparison between ring and disk shapes will be presented. The comparisons take into account the beam diameter and the beam intensity but also the effect of the angle of incidence will be presented. [less ▲]

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See detailPerformances comparison of a laser ultrasonic system using 10.6 µm infrared or 532 nm visible generation beam for the investigation of CFRP
Vandenrijt, Jean-François ULiege; Walter, Julien; Brouillette, Tomy et al

Conference (2016, July)

The investigation of complex shaped carbon fiber parts is a common need of the industry. Classical ultrasonic systems are commonly used, wide-spread and very efficient. However, these techniques are often ... [more ▼]

The investigation of complex shaped carbon fiber parts is a common need of the industry. Classical ultrasonic systems are commonly used, wide-spread and very efficient. However, these techniques are often limited to simple shape objects. Major problems arise when the shape of the element to be investigated is complex (peak, valley, small radius of curvature…). To overcome these problems laser ultrasonic systems can be used and the recent developments show promising results. Laser ultrasonic systems can use different wavelengths for ultrasound generation. Usually CO2 lasers emitting at 10.6 µm wavelength are used. When a laser ultrasonic system is mounted on a robotic arm, very complex shaped objects can be considered. However, the optical fibers for 10.6 µm wavelength are not capable to cope with laser ultrasonic system requirements. Therefore, infrared systems use jointed articulated beam delivery systems which reduce the flexibility of the robot arm and significantly limit the feasible scan paths. To circumvent this limitation, an all-fibered laser ultrasonic system can be used. In our case the ultrasound is generated with a pulsed laser operating at 532 nm. This system is placed on a robotic arm, the beam delivery is performed through an optical fiber only. Therefore, this system is capable of analyzing very complex shaped objects due to the use of optical fiber only for laser beam transport. But visible generation is known to be less efficient and produces lower quality signals. In order to balance the advantages and limitations of both of these systems a CFRP plate including artificial defects has been investigated with different ultrasonic systems. First we used classical phased-array ultrasounds as a reference to compare the performances of visible and infrared generation systems. The plate has then been investigated with a 10.6 µm laser ultrasonic system. The results are compared with an all-fibered laser ultrasonic system working at 532 mn wavelength. Data acquired by each system allow comparing the visibility of the ultrasonic echoes and the amplitude of background noise. We observe the impact of frequency filtering. We show the main differences on the A-scans and C-scan generated by each system. From these elements, we show the advantages and limitations of each system for the investigation of CFRP with a focus on complex shaped object. [less ▲]

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See detailVibration mode shapes visualization in industrial environment by real-time time-averaged phase-stepped electronic speckle pattern interferometry at 10.6  μm and shearography at 532 nm
Languy, Fabian ULiege; Vandenrijt, Jean-François ULiege; Thizy, Cédric ULiege et al

in Optical Engineering : The Journal of the Society of Photo-Optical Instrumentation Engineers (2016), 55(12), 121704

We present our investigations on two interferometric methods suitable for industrial conditions dedicated to the visualization of vibration modes of aeronautic blades. First, we consider long-wave ... [more ▼]

We present our investigations on two interferometric methods suitable for industrial conditions dedicated to the visualization of vibration modes of aeronautic blades. First, we consider long-wave infrared (LWIR) electronic speckle pattern interferometry (ESPI). The use of long wavelength allows measuring larger amplitudes of vibrations compared with what can be achieved with visible light. Also longer wavelengths allow lower sensitivity to external perturbations. Second, shearography at 532 nm is used as an alternative to LWIR ESPI. Both methods are used in time-averaged mode with the use of phase-stepping. This allows transforming Bessel fringes, typical to time averaging, into phase values that provide higher contrast and improve the visualization of vibration mode shapes. Laboratory experimental results with both techniques allowed comparison of techniques, leading to selection of shearography. Finally a vibration test on electrodynamic shaker is performed in an industrial environment and mode shapes are obtained with good quality by shearography. [less ▲]

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See detailMesures de déformation par ESPI de la surface d’un miroir chauffé et comparaison avec simulations numériques
Languy, Fabian ULiege; Vandenrijt, Jean-François ULiege; Saint-Georges, Philippe et al

Conference (2015, November)

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See detailCombination of temporal phase unwrapping and long-wave infrared digital holographic interferometry for metrology of mosaic detector under space simulated conditions
Vandenrijt, Jean-François ULiege; Thizy, Cédric ULiege; Beaumont, Florent et al

in Mendoza Santoyo, Fernando (Ed.) SPECKLE 2015: VI International Conference on Speckle Metrology (2015, August)

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

We present digital holographic interferometry (DHI) in the long-wave infrared for monitoring the deformation under cryogenic conditions of a segmented focal plane array 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 such temperature changes. The specimen consists of 4x4 mosaic of detectors assembled on a frame. It was required to assess the global deformation of the ensemble, 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 suffer strong variations. At last since the specimen exhibit specular reflectivity at that wavelength, it is illuminated through a reflective diffuser [less ▲]

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See detailTime-averaged phase-stepped ESPI with CO2 laser and shearography in the visible for identification of vibration mode shapes
Vandenrijt, Jean-François ULiege; Thizy, Cédric ULiege; Georges, Marc ULiege

in Mendoza Santoyo, Fernando (Ed.) SPECKLE 2015: VI International Conference on Speckle Metrology (2015, August)

We present investigation of interferometric methods for vibration mode identification to be applied on shakers in industrial environment. We consider long wave infrared ESPI in time-averaged mode with the ... [more ▼]

We present investigation of interferometric methods for vibration mode identification to be applied on shakers in industrial environment. We consider long wave infrared ESPI in time-averaged mode with the use of phase-stepping which allows transforming Bessel fringes, typical to the time averaging, into phase values which provide a better way for identification of vibration mode shapes. The use of long laser wavelength allows measuring larger amplitudes of vibrations compared to what is achieved in visible light. Also longer wavelengths allow lower sensitivity to external perturbations. Time-averaged phase-stepped shearography in visible is also used as a compared alternative to LWIR ESPI for working in industrial environments. Although not demonstrated here, an interesting feature for the future investigations on LWIR ESPI is its potentiality of simultaneous temperature measurement during vibrations [less ▲]

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See detailUse of specklegrams background terms for speckle photography combined with phase-shifting electronic speckle pattern interferometry
Zemmamouche, Redouane; Vandenrijt, Jean-François ULiege; Medjahed, Aïcha et al

in Optical Engineering : The Journal of the Society of Photo-Optical Instrumentation Engineers (2015), 54(8), 084110

Electronic speckle pattern interferometry (ESPI) is combined with digital speckle photography (DSP) to measure out-of-plane deformation in the presence of large in-plane translation or rotation. ESPI is ... [more ▼]

Electronic speckle pattern interferometry (ESPI) is combined with digital speckle photography (DSP) to measure out-of-plane deformation in the presence of large in-plane translation or rotation. ESPI is used to measure out-of-plane displacements smaller than the speckle diameter. In-plane displacements larger than the speckle size are obtained by DSP using artifacts images computed from the phase-stepped specklegrams. Previous works use the specklegram modulation for that purpose, but we show that this can lead to errors in the case of low modulation. In order to avoid this, a simple averaging of phase-stepped specklegrams allows obtaining the average irradiance, which contains information on the speckled object image. The latter can be used more efficiently than the modulation in DSP and is simpler to compute. We also perform a numerical simulation of specklegrams, which show that the use of background terms is much more stable against some error sources as compared to modulation. We show experimental evidence of this in various experiments combining out-of-plane ESPI measurements with in-plane translations or rotations obtained by our DSP method. The latter has been used efficiently to restore phase loss in out-of-plane ESPI measurements due to large in-plane displacements. [less ▲]

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See detailDevelopment of a full fiber-coupled laser ultrasound robotic system using two-wave mixing 1064 nm detection and 532 nm YAG generation
Vandenrijt, Jean-François ULiege; Simar, Juan Felipe ULiege; Thizy, Cédric ULiege et al

in Laser Ultrasonics and Advanced Sensing (2015, June)

An all-fibered laser ultrasonic system for complex shape composite parts is presented. It is based on two-wave mixing detection and a long pulse laser working at 1064 nm and generation by a fibered YAG Q ... [more ▼]

An all-fibered laser ultrasonic system for complex shape composite parts is presented. It is based on two-wave mixing detection and a long pulse laser working at 1064 nm and generation by a fibered YAG Q-switch laser working at 532 nm. A compact optical head combining both beams is interfaced to a robot system for scanning. Some practical issues of this system are studied. [less ▲]

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See detailLong-wave infrared digital holographic interferometry for deformation measurement of the segmented detector array of the space EUCLID mission
Vandenrijt, Jean-François ULiege; Thizy, Cédric ULiege; Beaumont, Florent et al

in Digital Holography and Three-Dimensional Imaging (2015, May)

Digital holographic interferometry in LWIR is used for following the deformation and relative movement of an assembly of detectors to be used in space. The setup is incorporated in a vacuum chamber for ... [more ▼]

Digital holographic interferometry in LWIR is used for following the deformation and relative movement of an assembly of detectors to be used in space. The setup is incorporated in a vacuum chamber for cryogenic testing. [less ▲]

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