References of "Thizy, Cédric"
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See detailPhotorefractive holographic camera for monitoring deformations of MEMS
Georges, Marc ULg; Thizy, Cédric ULg

in Journal of Micro/Nanolithography, MEMS, and MOEMS (2015), 14(4), 041301

We present the development of a holographic interferometer based on dynamic hologram recording with photorefractive crystals of the sillenite family and which is adapted for the observation of MEMS. A ... [more ▼]

We present the development of a holographic interferometer based on dynamic hologram recording with photorefractive crystals of the sillenite family and which is adapted for the observation of MEMS. A compact portable system was already presented in the past and used in various metrology and nondestructive applications on large scattering objects. It was emphasized the great versatility of the instrument which allows high resolution measurements. Here we show the development and achievement of an optical module which can be easily interfaced on the basic instrument, allowing small specular objects observation. Results of deformation of electrically actuated MEMS are shown. [less ▲]

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See detailFormation flying metrology for the ESA-PROBA3 mission: the Shadow Position Sensors (SPS) silicon photomultipliers (SiPMs) readout electronics
Focardi, M.; Bemporad, A.; Buckley, S. et al

in Proc. SPIE Volume 9604 Solar Physics and Space Weather Instrumentation VI (2015, September 21)

The European Space Agency (ESA) is planning to launch in 2018 the PROBA3 Mission, designed to demonstrate the inorbit formation flying (FF) attitude capability of its two satellites and to observe the ... [more ▼]

The European Space Agency (ESA) is planning to launch in 2018 the PROBA3 Mission, designed to demonstrate the inorbit formation flying (FF) attitude capability of its two satellites and to observe the inner part of the visible solar corona as the main scientific objective. The solar corona will be observed thanks to the presence on the first satellite, facing the Sun, of an external occulter producing an artificial eclipse of the Sun disk. The second satellite will carry on the coronagraph telescope and the digital camera system in order to perform imaging of the inner part of the corona in visible polarized light, from 1.08 Rsun up to about 3 Rsun. One of the main metrological subsystems used to control and to maintain the relative (i.e. between the two satellites) and absolute (i.e. with respect to the Sun) FF attitude is the Shadow Position Sensor (SPS) assembly. It is composed of eight micro arrays of silicon photomultipliers (SiPMs) able to measure with the required sensitivity and dynamic range the penumbral light intensity on the Coronagraph entrance pupil. In the following of the present paper we describe the overall SPS subsystem and its readout electronics with respect to the capability to satisfy the mission requirements, from the light conversion process on board the silicon-based SPS devices up to the digital signal readout and sampling. [less ▲]

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See detailThe Shadow Positioning Sensors (SPS) for formation flying metrology on-board the ESA-PROBA3 mission
Bemporad, A.; Baccani, C.; Capobianco, G. et al

in Proc. SPIE Volume 9604 Solar Physics and Space Weather Instrumentation VI (2015, September 21)

PROBA3 is an ESA technology mission devoted to in-orbit demonstration of the formation flight (FF) technique, with two satellites kept at an average inter-distance by about 144 m. The ASPIICS instrument ... [more ▼]

PROBA3 is an ESA technology mission devoted to in-orbit demonstration of the formation flight (FF) technique, with two satellites kept at an average inter-distance by about 144 m. The ASPIICS instrument on-board PROBA3 will be the first ever space-based coronagraph working on one satellite and having the external occulter located on the second satellite, thus allowing observations of the inner solar corona with unprecedented reduction of stray light. During the observational periods, the FF configuration will be maintained with very high precision and two different techniques will be implemented: the use of Shadow Positioning Sensors (SPS) located on the Coronagraph Spacecraft (diodes measuring the penumbral light intensity on the entrance pupil plane) and the use of Occulter Position Sensor LEDs (OPSE) located on the back side of the Occulter Spacecraft. This paper will review the main instrumental requirements on the SPS needed to determine the 3-dimensional relative positioning of the two PROBA3 satellites with the high precision and frequency. [less ▲]

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See detailSignificance of the occulter diffraction for the PROBA3/ASPIICS formation flight metrology
Landini, F.; Bemporad, A.; Focardi, M. et al

in Proc. SPIE Volume 9604 Solar Physics and Space Weather Instrumentation VI (2015, September 21)

PROBA-3/ASPIICS is a formation Flying coronagraph selected by ESA and currently in its C/D phase. It is constituted by two spacecrafts (OSC, Occulter SpaceCraft, carrying the occulter, diameter 142 cm ... [more ▼]

PROBA-3/ASPIICS is a formation Flying coronagraph selected by ESA and currently in its C/D phase. It is constituted by two spacecrafts (OSC, Occulter SpaceCraft, carrying the occulter, diameter 142 cm, and CSC, Coronagraph SpaceCraft, with the telescope) separated by ~144 m, kept in strict alignment by means of an active custom system. The alignment active system most critical components are the Shadow Positioning Sensors (SPS), a series of Si-PM (Silicon Photomultiplier) measuring the penumbra generated by the occulter. The arrangement of the SPSs around the telescope entrance aperture is defined as a trade-off between mechanical constraints and maximum sensitivity to misalignments. The signal detected by the SPSs can be approximately simulated with a geometrical analysis based on the variation of the penumbra generated by the external occulter. The stray light generated by the diffraction from the external occulter may affect the SPSs signal. It is mandatory to carefully evaluate its level in order to refine the active alignment adjustment algorithm. This work is dedicated to the description of the preliminary investigation performed in order to evaluate the impact of the diffraction on the SPSs signal. [less ▲]

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See detailDesign status of ASPIICS, an externally occulted coronagraph for PROBA-3
Renotte, Etienne ULg; Alia, A.; Bemporad, A. et al

in Proc. SPIE Volume 9604 Solar Physics and Space Weather Instrumentation VI (2015, September 21)

The “sonic region” of the Sun corona remains extremely difficult to observe with spatial resolution and sensitivity sufficient to understand the fine scale phenomena that govern the quiescent solar corona ... [more ▼]

The “sonic region” of the Sun corona remains extremely difficult to observe with spatial resolution and sensitivity sufficient to understand the fine scale phenomena that govern the quiescent solar corona, as well as phenomena that lead to coronal mass ejections (CMEs), which influence space weather. Improvement on this front requires eclipse-like conditions over long observation times. The space-borne coronagraphs flown so far provided a continuous coverage of the external parts of the corona but their over-occulting system did not permit to analyse the part of the white-light corona where the main coronal mass is concentrated. The proposed PROBA-3 Coronagraph System, also known as ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun), with its novel design, will be the first space coronagraph to cover the range of radial distances between ~1.15 and 3 solar radii where the magnetic field plays a crucial role in the coronal dynamics, thus providing continuous observational conditions very close to those during a total solar eclipse. PROBA-3 is first a mission devoted to the in-orbit demonstration of precise formation flying techniques and technologies for future European missions, which will fly ASPIICS as primary payload. The instrument is distributed over two satellites flying in formation (approx. 150m apart) to form a giant coronagraph capable of producing a nearly perfect eclipse allowing observing the sun corona closer to the rim than ever before. The coronagraph instrument is developed by a large European consortium including about 20 partners from 7 countries under the auspices of the European Space Agency. This paper is reviewing the recent improvements and design updates of the ASPIICS instrument as it is stepping into the detailed design phase. [less ▲]

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See detailOPSE metrology system onboard of the PROBA3 mission of ESA
Loreggia, D.; Bemporad, A.; Capobianco, G. et al

in Proc. SPIE Volume 9604 Solar Physics and Space Weather Instrumentation VI (2015, September 21)

In recent years, ESA has assessed several mission involving formation flying (FF). The great interest in this topics is mainly driven by the need for moving from ground to space the location of next ... [more ▼]

In recent years, ESA has assessed several mission involving formation flying (FF). The great interest in this topics is mainly driven by the need for moving from ground to space the location of next generation astronomical telescopes overcoming most of the critical problems, as example the construction of huge baselines for interferometry. In this scenario, metrology systems play a critical role. PROBA3 is an ESA technology mission devoted to in-orbit demonstration of the FF technique, with two satellites, an occulter and a main satellite housing a coronagraph named ASPIICS, kept at an average inter-distance by about 144m, with micron scale accuracy. The guiding proposal is to test several metrology solution for spacecraft alignment, with the important scientific return of having observation of Corona at never reached before angular field. The Shadow Position Sensors (SPS), and the Optical Position Emitters Sensors (OPSE) are two of the systems used for FF fine tracking. The SPS are finalized to monitor the position of the two spacecraft with respect to the Sun and are discussed in dedicated papers presented in this conference. The OPSE will monitor the relative position of the two satellites and consists of 3 emitters positioned on the rear surface of the occulter, that will be observed by the coronagraph itself. By following the evolution of the emitters images at the focal plane the alignment of the two spacecrafts is retrieved via dedicated centroiding algoritm. We present an overview of the OPSE system and of the centroiding approach. [less ▲]

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See detailDesign and modelisation of ASPIICS optics
Galy, Camille ULg; Fineschi, S.; Galano, D. et al

in Proc. SPIE Volume 9604 Solar Physics and Space Weather Instrumentation VI (2015, September 21)

In the framework of development of ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun), the Centre Spatial de Liege is responsible of the optical design ... [more ▼]

In the framework of development of ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun), the Centre Spatial de Liege is responsible of the optical design of the coronagraph and the optics will be manufactured by TOPTEC. The particularity of this coronagraph is to have an external occulter located 150 m ahead of the first imaging lens. This external occulter is re-imaged on an internal occulter which function is - as in a classical externally occulted Lyot coronagraph - to block the sun light diffracted by the external occulter and to reduce the straylight on the detector. The selection of this configuration is driven by the requirement to observe the corona as close as possible to the solar limb (i.e. 1 RSun) without imaging the limb itself. A requirement of 1.08 RSun is specified at optical design level to grant 1.2 Rsun at instrument level. The coronograph instrument is designed to have a field of view of 1.6° x 1.6° with a resolution of less than 6 arcsec. Its performances are limited by diffraction in a 530 – 590 nm wavelength range. This paper presents the optical design and demonstrates that by design the requirements are fulfilled within the misalignment, manufacturing and thermo-elastic error contributions. [less ▲]

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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 ULg; Thizy, Cédric ULg; 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 ULg; Thizy, Cédric ULg; Georges, Marc ULg

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 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 ULg; Simar, Juan Felipe ULg; Thizy, Cédric ULg 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 ULg; Thizy, Cédric ULg; 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 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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