References of "Tychon, Isabelle"
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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 detailDynamic holography for the space qualification of large reflectors
Thizy, Cédric ULg; Stockman, Yvan ULg; Doyle, D. et al

in Optical Fabrication, Testing, and Metrology II (2005, October)

The next generation of infrared - sub mm space telescopes requires reflectors with large dimensions, high quality and, according to weight issues, are based on composite or new materials technology. The ... [more ▼]

The next generation of infrared - sub mm space telescopes requires reflectors with large dimensions, high quality and, according to weight issues, are based on composite or new materials technology. The challenging tasks of on-ground testing are to achieve the required accuracy in the measurement of these reflectors shape and antenna structures and to verify their performance under simulated space conditions (vacuum, low-high temperatures). A holographic camera for the verification and validation of this type of reflector in a space environment is presented. A diffuser is implemented to measure the deformations of reflective surfaces in a more flexible way. The system has been made compatible with the vacuum conditions. Some elements of the holographic camera (camera lenses, CCD, crystal, optical fibre) have been adapted and tested under vacuum. The metrological certification of the whole system is realised by the measurement of a parabolic CFRP reflector with a 1.1 meter diameter. The results are compared to the one achieved with a high spatial resolution IR interferometer on the same reflector in laboratory conditions and under thermal vacuum conditions. This later test consists in measuring the deformations of the reflector between an initial state at a selected temperature and a final state at another temperature. The comparison between the high spatial resolution IR interferometer and this dynamic holographic method showed very good qualitative and quantitative agreement between the techniques, thus verifying the potential of this new Holographic approach. [less ▲]

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See detailQualification of large reflectors in space environment with a holographic camera based on a BSO crystal
Thizy, Cédric ULg; Stockman, Yvan ULg; Lemaire, Philippe ULg et al

in Zhang, G.; Kip, D.; Nolte, D. (Eds.) et al Photorefractive Effects, Materials, and Devices (2005, July)

The next generation of infrared - sub mm space telescopes requires some reflectors with large dimensions and high quality. These ones, according to weight issues, are based on composite materials for ... [more ▼]

The next generation of infrared - sub mm space telescopes requires some reflectors with large dimensions and high quality. These ones, according to weight issues, are based on composite materials for which the behaviors at low temperatures are badly known. A holographic interferometry method for the verification and validation of this type of reflectors in a space environment is presented. It is based on a dynamic holographic camera observing a diffuser illuminated by the object beam coming from the reflecting surface. Photorefractive crystals being self-processing and reusable mediums, the measuring range of the holographic camera is increased with respect to other optical interferometric methods. The metrological certification of the whole system was realised by the measurement of a parabolic antenna with a 1.1 meter diameter, a known behavior and placed in a simulated space environment [less ▲]

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See detailDesign and verification of the Far Ultraviolet Spectrographic Imager (FUV-SI) for the IMAGE mission
Renotte, Etienne ULg; Habraken, Serge ULg; Rochus, Pierre ULg et al

in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (1998, November 01)

The IMAGE FUV-SI is simultaneously imaging auroras at 121.8 nm and 135.8 nm. The spectrograph design challenge is the efficient rejection of the intense Lyman-alpha emission at 121.6 nm while passing its ... [more ▼]

The IMAGE FUV-SI is simultaneously imaging auroras at 121.8 nm and 135.8 nm. The spectrograph design challenge is the efficient rejection of the intense Lyman-alpha emission at 121.6 nm while passing its Doppler-shifted component at 121.8 nm. The FUV-SI opto-mechanical design, analysis integration, and verification of performances against environment are discussed in this paper. In absence of STM environmental constraints at subsystem levels are derived analytically from F.E.M. and used for pre-qualifying optical subsystems. [less ▲]

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