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See detailOptic nerve sheath meningiomas
Litré, Claude Fabien ULg; Colin, P; Rousseaux, P et al

in Neuro-Chirurgie (2010), 56(2-3),

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See detailOptical analysis of particle size and chromite liberation from pulp samples of a UG2 ore regrinding circuit
Leroy, Sophie ULg; Dislaire, Godefroid; Bastin, David ULg et al

in Minerals Engineering (2011), 24

Since the early seventies high chromite and low base metal sulphide (BMS) contents of the UG2 reef imposes technological challenges to mineral processors and extractive metallurgists. Forty years later ... [more ▼]

Since the early seventies high chromite and low base metal sulphide (BMS) contents of the UG2 reef imposes technological challenges to mineral processors and extractive metallurgists. Forty years later, particle size distribution and size by size mineralogy are considered as key factors to the continuous improvement of the UG-2 ore metallurgy. With the successful development of ultra fine grinding technologies, a compromise has to be found between fine grinding to achieve platinum group minerals liberation and to avoid the overgrinding of gangue minerals, especially chromite gangue which is detrimental in smelting process. Indeed, fine chromite grains, despite of being naturally hydrophobic mineral, can be recovered in flotation concentrate by entrainment. In addition, overgrinding also increase liberation of naturally floatable gangue (talc) which contaminate the concentrate and need to be controlled during flotation. In this paper, innovative techniques of single particle image analysis from both dry and wet samples have been tentatively used to assess the chromite particle size distribution and the chromite grade of samples taken from a secondary milling circuit. Preliminary results demonstrate excellent potential for online particle imaging making use of both the particle geometry (size, shape) and the optical properties (translucency). [less ▲]

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See detailOptical and magnetic properties of Fe2+ and Cr2+ in II-VI semiconductors: The Jahn-Teller effect
Colignon, David ULg; Kartheuser, Eduard ULg; Rodriguez, Sergio et al

in Journal of Crystal Growth (1996), 159(1-4), 875-878

The D-5 terms of Fe2+ and Cr2+ in the tetrahedral potential at cation sites in II-VI compounds split into orbital doublet and triplet states. While in Cr2+ the orbital tripler has lower energy than the ... [more ▼]

The D-5 terms of Fe2+ and Cr2+ in the tetrahedral potential at cation sites in II-VI compounds split into orbital doublet and triplet states. While in Cr2+ the orbital tripler has lower energy than the doublet the opposite is the case in Fe2+. Both ions have singlet ground states after the spin-orbit interaction is taken into account and, hence, both are Van Vleck paramagnets. The optical absorption spectra of Fe and Cr based materials differ and are explained on the basis of a dynamic Jahn-Teller effect in the former and a static one in the latter. These considerations permit us to explain the optical as well as the magnetic properties observed in these materials. [less ▲]

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See detailOptical and mechanical design of a straylight rejection baffle for CoRoT
Plesseria, Jean-Yves ULg; Mazy, Emmanuel ULg; Defise, Jean-Marc ULg et al

in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (2003, November 01)

The COROT mission is part of the program "Petites Missions" of CNES (French space agency). It implies international cooperation between France, Belgium, Germany, Austria, Spain and the European Space ... [more ▼]

The COROT mission is part of the program "Petites Missions" of CNES (French space agency). It implies international cooperation between France, Belgium, Germany, Austria, Spain and the European Space Agency (ESA). COROT aims to perform astroseismology measurements and to detect exoplanets. Long duration observations of stars will be used to detect periodic variations with an afocal telescope followed by a dioptric objective and 4 CCDs. Due to the orbit of the spacecraft (low altitude polar orbit) and even if the observation are performed in a direction perpendicular to orbit plane, the measurements can be disturbed by the straylight reflected on the earth (albedo) that can generate periodic perturbation. CSL is in charge of the design and procurement, with the help of Belgian industries, of a baffle and its protective cover that will be mounted on top of the afocal entrance telescope. The requirements are very stringent from the optical point of view as well as from the mechanical point of view. The rejection of the baffle must be of the order of 10[SUP]13[/SUP] for field angles above 20 degrees while the allocated mass is 19 kilograms. [less ▲]

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See detailOptical and structural characterization of TiO2 films doped with silver nanoparticles obtained by sol-gel method
Ivanova, T.; Harizanova, A.; Koutzarova, T. et al

in Optical Materials (2013), 36

Nanostructured titanium oxide films with incorporated Ag nanoparticles were deposited by sol-gel spin coating method. The films were annealed at 300 °C, 400 °C, 500 °C and 600 °C in oxygen and nitrogen ... [more ▼]

Nanostructured titanium oxide films with incorporated Ag nanoparticles were deposited by sol-gel spin coating method. The films were annealed at 300 °C, 400 °C, 500 °C and 600 °C in oxygen and nitrogen ambient. X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and UV-VIS spectroscopy had been applied for studying the influence of the thermal treatments and the gas ambient on the structural and optical properties of TiO2 and TiO2:Ag films. The XRD analysis revealed the presence of metallic Ag phase without traces of silver oxides and these results were confirmed by FTIR spectra. It has been revealed that the annealing temperatures and the ambient, where the annealing is carried out is crucial for TiO2 crystallization, when there is Ag incorporation and especially for appearance of anatase and rutile phase. The nitrogen and oxygen ambient influences quite different the crystallization of TiO2:Ag films. Transmission and absorption spectra have been analyzed. Optical band gap values were evaluated for pure titania and Ag incorporated TiO2 films. © 2013 Elsevier B.V. All rights reserved. [less ▲]

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See detailOptical calibration of the FUV spectrographic imager for the IMAGE mission
Habraken, Serge ULg; Houbrechts, Yvette ULg; Renotte, Etienne ULg et al

in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (1999, October 01)

The FUV Spectrographic Imager for IMAGE is simultaneously imaging auroras at 1218 and 1358 angstrom. It is designed to efficiently reject the Lyman-(alpha) emission line at 1215.7 angstrom. This paper ... [more ▼]

The FUV Spectrographic Imager for IMAGE is simultaneously imaging auroras at 1218 and 1358 angstrom. It is designed to efficiently reject the Lyman-(alpha) emission line at 1215.7 angstrom. This paper describes the optical calibration. The content is: 1) field of view calibration: detector pixels location with respect to the reference optical cube; distortion matrix used to computer the TDI. b) Radiometric calibration: detector response and linearity; instrument throughput according to its clear aperture and mirror reflection lost; response vs. wavelength and band-rejection certification. [less ▲]

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See detailOptical circular polarization in quasars
Hutsemekers, Damien ULg; Borguet, Benoît ULg; Sluse, D. et al

in Astronomy and Astrophysics (2010), 520(Letters), 71-5

We present new optical circular polarization measurements with typical uncertainties <0.1% for a sample of 21 quasars. All but two objects have null circular polarization. We use this result to constrain ... [more ▼]

We present new optical circular polarization measurements with typical uncertainties <0.1% for a sample of 21 quasars. All but two objects have null circular polarization. We use this result to constrain the polarization due to photon-pseudoscalar mixing along the line of sight. We detect significant (> 3σ) circular polarization in two blazars with high linear polarization and discuss the implications of this result for quasar physics. In particular, the recorded polarization degrees may be indicative of magnetic fields as strong as 1 kG or a significant contribution of inverse Compton scattering to the optical continuum. Based on observations made with ESO Telescopes at the La Silla Observatory (Chile). ESO program ID: 79.A-0625(B).Appendices are only available in electronic form at <A href="http://www.aanda.org">http://www.aanda.org</A> [less ▲]

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See detailOptical design of the FUV spectrographic imager for the IMAGE mission
Habraken, Serge ULg; Jamar, Claude ULg; Rochus, Pierre ULg et al

in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (1997)

This paper describes the original concept and the optical design of the IMAGE mission FUV spectrographic imager (SI). The instrument goal is to spectrally separate and image the electron and proton ... [more ▼]

This paper describes the original concept and the optical design of the IMAGE mission FUV spectrographic imager (SI). The instrument goal is to spectrally separate and image the electron and proton auroras. A 30 angstrom (3 nm) spectral resolution is required to isolate the electron auroras (1356 angstrom). The proton aurora imaging requires to efficiently mask the geocoronal Lyman-alpha line (1216 angstrom), in order to image the Doppler shifted Lyman-alpha light (1217 - 1223 angstrom). A classical SI combines a telescope with a spectrometer. Our SI is consisting of a reverse combination: (1) a multi-slits Wadsworth monochromator designed to spectrally isolate the two bandwidths (electrons and protons auroras), (2) a two mirror imager with a crossed delay line detector producing the final imaging on each spectral channel. [less ▲]

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See detailOptical Device For Projection Display System
Habraken, Serge ULg

Patent (2002)

An optical system to track a laser pointer in a multi media presentation. The information is used for dispaying symbols or activation of controls

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See detailOptical evolution of Nova Ophiuchi 2007 = V2615 Oph
Munari, U.; Henden, A.; Valentini, Marica ULg et al

in Monthly Notices of the Royal Astronomical Society (2008), 387

The moderately fast Nova Oph 2007 reached maximum brightness on 2007 March 28 at V = 8.52, B - V = +1.12, V - R[SUB]C[/SUB] = +0.76, V - I[SUB]C[/SUB] = +1.59 and R[SUB]C[/SUB] - I[SUB]C[/SUB] = +0.83 ... [more ▼]

The moderately fast Nova Oph 2007 reached maximum brightness on 2007 March 28 at V = 8.52, B - V = +1.12, V - R[SUB]C[/SUB] = +0.76, V - I[SUB]C[/SUB] = +1.59 and R[SUB]C[/SUB] - I[SUB]C[/SUB] = +0.83, after fast initial rise and a pre-maximum halt lasting a week. Decline times were t[SUP]V[/SUP][SUB]2[/SUB] = 26.5, t[SUP]B[/SUP][SUB]2[/SUB] = 30, t[SUP]V[/SUP][SUB]3[/SUB] = 48.5 and t[SUP]B[/SUP][SUB]3[/SUB] = 56.5 d. The distance to the nova is d = 3.7 +/- 0.2 kpc, the height above the Galactic plane is z = 215 pc, the reddening is E(B - V) = 0.90 and the absolute magnitude at maximum is M[SUP]max[/SUP][SUB]V[/SUB] = -7.2 and M[SUP]max[/SUP][SUB]B[/SUB] = -7.0. The spectrum four days before maximum resembled a F6 supergiant, in an agreement with broad-band colours. It later developed into that of a standard `FeII'-class nova. Nine days past maximum, the expansion velocity estimated from the width of Hα emission component was ~730 km s[SUP]-1[/SUP], and the displacement from it of the principal and diffuse-enhanced absorption systems was ~650 and 1380 km s[SUP]-1[/SUP], respectively. Dust probably formed and disappeared during the period from 82 to 100 d past maximum, causing (at peak dust concentration) an extinction of ΔB = 1.8 mag and an extra ΔE(B - V) = 0.44 reddening. [less ▲]

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See detailThe optical gravitational lens experiment
Surdej, Jean ULg; Refsdal, S.; Pospieszalska-Surdej, Anna ULg

in Surdej, Jean; Fraipont-Caro, D.; Gosset, E. (Eds.) et al Proceedings of the 31st Liege International Astrophysical Colloquium (LIAC 93) (1993)

Not Available

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See detailOptical imaging of gravitational lenses B1422+231
Remy, M.; Surdej, Jean ULg; Smette, A. et al

in Surdej, Jean; Fraipont-Caro, D.; Gosset, Eric (Eds.) et al Liege International Astrophysical Colloquia,Gravitational Lenses in the Universe (1993)

We report here on some of the major developments achieved on optical observations of gravitational lenses since the last conference devoted to 'Gravitational Lensing'.

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See detailOptical imaging of the gravitational lens system B 1422+231
Remy; Surdej, Jean ULg; Smette, A. et al

in Astronomy and Astrophysics (1993), 278

Direct optical images (Bessel V, R and Gunn i; average seeing of 0.88 seconds) of B1422+231, obtained in March 1993 at European Southern Observatory (ESO) (La Silla), have been decomposed by fitting ... [more ▼]

Direct optical images (Bessel V, R and Gunn i; average seeing of 0.88 seconds) of B1422+231, obtained in March 1993 at European Southern Observatory (ESO) (La Silla), have been decomposed by fitting multiple Point Spread Functions (PSFs). We detect the optical counterparts of the four known radio point-like components. No additional optical image is found, but due to the compactness of the configuration, our detection limit for additional point sources is rather low (19.3 in R). The deduced positions and photometry of the four optical components agree pretty well with the radio and IR observations and this study provides further evidence supporting the gravitational lens origin of B1422+231. [less ▲]

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See detailOptical methods for non-contact measurements of membranes
Roose, Stéphane ULg; Stockman, Yvan ULg; Rochus, Pierre ULg et al

in Acta Astronautica (2009), 65(9-10), 1317-1329

Structures for space applications very often suffer stringent mass constraints. Lightweight structures are developed for this purpose, through the use of deployable and/or inflatable beams, and thin-film ... [more ▼]

Structures for space applications very often suffer stringent mass constraints. Lightweight structures are developed for this purpose, through the use of deployable and/or inflatable beams, and thin-film membranes. Their inherent properties (low mass and small thickness) preclude the use of conventional measurement methods (accelerometers and displacement transducers for example) during on-ground testing. In this context, innovative non-contact measurement methods need to be investigated for these stretched membranes. The object of the present project is to review existing measurement systems capable of measuring characteristics of membrane space-structures such as: dot-projection videogrammetry (static measurements), stereo-correlation (dynamic and static measurements), fringe projection (wrinkles) and 3D laser scanning vibrometry (dynamic measurements). Therefore, minimum requirements were given for the study in order to have representative test articles covering a wide range of applications. We present test results obtained with the different methods on our test articles. [less ▲]

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See detailOPTICAL MULTICHANNEL ANALYSIS OF PROTOCHLOROPHYLLIDE PHOTOTRANSFORMATION IN DETERGENT-SOLUBILIZED ETIOPLAST MEMBRANES OF WHEAT
Franck, Fabrice ULg; OUAZZANI, M. A.; DUJARDIN, E. et al

in Zeitschrift Fur Naturforschung C-A Journal Of Biosciences (1994), 49(1-2), 125-131

Extracts of wheat etioplast membranes obtained after treatment with 7 mM n-octyl-beta-D-glucopyranoside (OG), n-dodecyl-beta-D-maltoside (DM) or Triton X-100 contained the three spectral forms of Pchlide ... [more ▼]

Extracts of wheat etioplast membranes obtained after treatment with 7 mM n-octyl-beta-D-glucopyranoside (OG), n-dodecyl-beta-D-maltoside (DM) or Triton X-100 contained the three spectral forms of Pchlide (the photoactive Pchlide(638) and Pchlide(638) and the inactive Pchlide(650)) in various relative amounds. The OG extract had a Pchlide composition close to that of the intact membranes whereas the DM extract was enriched in Pchlide(638) and the Triton extract was enriched in Pchlide(630). Measurements of the kinetics of phototransformation and of time-resolved absorbance spectra during phototransformation in continuous Light shows that the inactive Pchlide(630) is in fact slowly transformed to Chlide, especially in the Triton extract where this form is more abundant. Addition of NADPH favours the phototransformation of Pchlide(630) and the slow regeneration of Pchlide(638) and Pchlide(650) from Pchlide(630) in darkness after illumination. No such regeneration was however observed in the Triton extract. NADPH had only slight effects on the Chlide shift towards shorter wavelengths after phototransformation in solubilized membranes. [less ▲]

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