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See detailMethod for manufacturing an improved optical layer of light emitting device with surface nano-micro texturation based on coherent electromagnetic radiation speckle lithography
Loicq, Jerôme ULg; Fleury-Frenette, Karl ULg; Vandormael, Denis

Patent (2012)

An object of the present invention is to provide a cheap, rapid, controlled, reproducible and polyvalent method for manufacturing a light emitting device with an internal source of light capable of ... [more ▼]

An object of the present invention is to provide a cheap, rapid, controlled, reproducible and polyvalent method for manufacturing a light emitting device with an internal source of light capable of achieving an enhancement in extraction efficiency. The invention proposes a method for manufacturing an optical layer for a light emitting device having an internal source of light and an optical layer separating the internal source of light and an external medium of light diffusion, wherein the method comprises the use of coherent electromagnetic radiation speckle lithography, such as laser speckle lithography, to make a nano/micro texturation on at least one surface of the optical layer [less ▲]

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See detailExperimental Results of Flat Fresnel Doublets made of PMMA and PC
Languy, Fabian ULg; Fleury-Frenette, Karl ULg; Lenaerts, Cedric ULg et al

Conference (2012, April)

To reduce the chromatic aberration lots of imaging systems like cameras and telescopes turn to achromatic doublets. On the other hand, to be cheaper, lighter and thinner, more and more systems like ... [more ▼]

To reduce the chromatic aberration lots of imaging systems like cameras and telescopes turn to achromatic doublets. On the other hand, to be cheaper, lighter and thinner, more and more systems like projectors and headlights use Fresnel lenses. To combine high performances and low cost, the use achromatic Fresnel doublets has been investigated. [less ▲]

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See detailIntegrated prism-free coupled surface plasmon resonance biochemical sensor
Lenaerts, Cedric ULg; Hastanin, Juriy ULg; Pinchemel, Bernard et al

in Proceedings of SPIE (2012), 8424

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See detailExperimental investigation of droplet biosensing by multi-wavelength plasmonic
Desfours, Caroline ULg; Habraken, Serge ULg; Hastanin, Juriy ULg et al

in Proceedings of SPIE Vol. 8234 : Plasmonics in Biology and Medicine IX (2012)

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See detailRipple topography and roughness evolution on surface of polycrystalline gold and silver thin films under low energy Ar-ion beam sputtering
Gailly, Patrick ULg; Petermann, Claire; Tihon, Pierre et al

in Applied Surface Science (2012), 258

Metallic thin films of gold and silver have been sputtered by argon ions at low energy in the framework of technological applications including nanostructuring and ion beam figuring. Ion beam sputtering ... [more ▼]

Metallic thin films of gold and silver have been sputtered by argon ions at low energy in the framework of technological applications including nanostructuring and ion beam figuring. Ion beam sputtering at high angle of incidence usually leads to spontaneous formation of periodic structures on the target surface, commonly referred as ripples. In this work, ripples dimensions and roughness evolution have been studied as function of the angle of incidence (0–80°), ion beam energy (400 – 1200 eV) and ion flux. The ripple wave vector direction was always observed perpendicular to the ion beam direction for both materials, in agreement with theoretical predictions for the investigated experimental conditions. The decrease of ripple wavelength with energy and ion flux shows the dominance of thermal diffusion as smoothing mechanism. Moreover, three regimes for roughness evolution on gold and silver films have been observed as function of the angle of incidence for sputtering at 650 eV, with a minimum roughness achieved around 45° and 60° for gold and silver, respectively. [less ▲]

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See detailOLED Light extraction improvement with surface nano-micro texturation based on speckle lithography.
Loicq, Jerôme ULg; Fleury-Frenette, Karl ULg; Viville, Pascal et al

in Physiscs and Optics of OLEDs (2012)

Part of the light rays generated within a luminescent medium with a higher refractive index than that of the exit medium, typically air, undergo total internal reflection phenomenon (TIR); these rays will ... [more ▼]

Part of the light rays generated within a luminescent medium with a higher refractive index than that of the exit medium, typically air, undergo total internal reflection phenomenon (TIR); these rays will be trapped and guided into the emissive material and will not be extracted out of an OLED device for instance. Trapped light is reabsorbed and eventually converted into heat that will be detrimental to the device performance and lifetime. The amount of trapped energy is highly dependent on the values of the refractive indices involved in the multilayer stack constituting the light emitting device. The amount of trapped energy can be extensive and can even reach as much as 75% in certain cases. Solutions to improve the outcoupling efficiency are therefore attractive. In this paper we propose to use laser speckle to produce a random surface with controlled parameters to enhance the OLED outcoupling. A laser speckle pattern is transferred onto a photoresist which will be subsequently converted into a surface relief profile. The optical setup parameters drive the properties of such surface and thus the outcoupling properties. The resulting surface has a quasi-random shape which could be assimilated to a corrugated surface. We will show that these typical surfaces exhibit light extraction enhancement properties. The generated pattern is then transferred onto the exit interfaces of the emitting device. An extraction improvement close to a factor 3 is measured. We finally discuss a practical case for which the laser speckle shape is applied to texture the surface of encapsulating cover glasses in a top-emitting OLED on steel substrates. [less ▲]

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See detailThe Solar Sail Materials (SSM) project – Status of activities
Della Vedova, Florio; Henrion, Didier; Leipold, Manfred et al

in Advances in Space Research (2011), 48(11), 1922-1926

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See detailUltrathin EUV Filters Testing and Characterization under High Flux (13 SC) for Solar Orbiter EUI Instrument
Jacques, Lionel ULg; Halain, Jean-Philippe ULg; Rossi, Laurence ULg et al

Conference (2011, October 07)

The test setup and characterization parameters of ultrathin EUV filters under high solar flux are presented. These 150nm thick aluminium filters are used at the entrance of the Extreme Ultraviolet Imager ... [more ▼]

The test setup and characterization parameters of ultrathin EUV filters under high solar flux are presented. These 150nm thick aluminium filters are used at the entrance of the Extreme Ultraviolet Imager (EUI) payload, which is developed at the Centre Spatial de Liège for the Solar Orbiter ESA M-class mission. The solar flux that they shall have to withstand will be as high as 13 solar constants when the spacecraft reach its 0.28AU perihelion. A specific design based on additional ribs has therefore been developed to enhance the thermal behaviour and heat evacuation while preserving its optical properties. It is essential to assess the design performances under the Solar Orbiter high solar flux. Therefore, thermal vacuum test under 13 solar constants will be performed. The filters temperature profiles will be measured during the tests through infrared imaging. A thermal correlation of the test will then be performed to deduce the filters actual thermal properties to be used in the global instrument geometrical and thermal mathematical models. [less ▲]

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See detailFlat Fresnel doublets made of PMMA and PC: combining low cost production and very high concentration ratio for CPV
Languy, Fabian ULg; Fleury-Frenette, Karl ULg; Lenaerts, Cedric ULg et al

in Optics Express (2011), 19(S3), 280-294

The linear chromatic aberration (LCA) of several combinations of polycarbonates (PCs) and poly (methyl methacrylates) (PMMAs) as singlet, hybrid (refractive/diffractive) lenses and doublets operating with ... [more ▼]

The linear chromatic aberration (LCA) of several combinations of polycarbonates (PCs) and poly (methyl methacrylates) (PMMAs) as singlet, hybrid (refractive/diffractive) lenses and doublets operating with wavelengths between 380 and 1600 nm – corresponding to a typical zone of interest of concentrated photovoltaics (CPV) – are compared. Those comparisons show that the maximum theoretical concentration factor for singlets is limited to about 1000 × at normal incidence and that hybrid lenses and refractive doublets present a smaller LCA increasing the concentration factor up to 5000 × and 2 × 106 respectively. A new achromatization equation more useful than the Abbé equation is also presented. Finally we determined the ideal position of the focal point as a function of the LCA and the geometric concentration which maximizes the flux on the solar cell. [less ▲]

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See detailUltra-short pulse fibre laser parameters optimisation for CdTe thin film solar cells processing and fibre laser design
Duterte, Charles; Lecourt, Jean-Bernard; Cserteg, A. et al

in Fiber Laser Applications, OSA Technical Digest (CD), paper FThC3 (2011, February 16)

We present the results of an optimization study of ultra-short pulse laser scribing of thin film CdTe solar cells. Thereafter, a fibre laser source has been designed and the first results are also ... [more ▼]

We present the results of an optimization study of ultra-short pulse laser scribing of thin film CdTe solar cells. Thereafter, a fibre laser source has been designed and the first results are also included here. [less ▲]

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See detailA spectral surface plasmon resonance sensor based on transmission grating: architecture analysis dedicated to spectral sensors
Hastanin, Juriy ULg; Lenaerts, Cedric ULg; Fleury-Frenette, Karl ULg et al

(2010, September)

Surface Plasmons Resonance (SPR) architectures based on grating coupler/disperser combination is an attractive alternative for spectral-based sensing. We present a new concept where the plasmon coupling ... [more ▼]

Surface Plasmons Resonance (SPR) architectures based on grating coupler/disperser combination is an attractive alternative for spectral-based sensing. We present a new concept where the plasmon coupling occurs through thin film grating and sensing occurs via the first diffraction order in reflective or transmitive mode. The developed geometry is dedicated to droplet sensing. The extension of the architecture to bi-dimensional array of sensors is also facilitated. This paper describes several designs of sensors. The analysis of their theoretical performances is demonstrated and compared, including a sensitivity evaluation. [less ▲]

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See detailNanoparticles in solar sail materials
Fleury-Frenette, Karl ULg

Conference (2010)

Solar sailing is a spacecraft propulsion mean exploiting the radiation pressure of sunlight. This concept is undergoing a regain of interest from the space agencies around the world partly driven by the ... [more ▼]

Solar sailing is a spacecraft propulsion mean exploiting the radiation pressure of sunlight. This concept is undergoing a regain of interest from the space agencies around the world partly driven by the development of manufacturing technologies. Typically, tens of thousands of square meters of sail materials are required to propel a spacecraft. In its most common proposed embodiment, the sail material is constituted of a thin polymer foil coated with a reflective layer on the front side and eventually an emissive layer on the back side. The photons momentum is transferred to the sail upon reflection and its thermal balance is governed by radiative processes (absorption over the solar spectrum and reemission of thermal infrared radiation). The impact of nanoparticles inclusion in the polymer foil on the sail performance will be evaluated for operation in the inner solar system. The aspects of passive thermal regulation and resistance of the polymer to UV radiation will be addressed within the framework of optical calculations based on effective media approximations. Copyright ©2010 by the International Astronautical Federation. All rights reserved. [less ▲]

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See detailThermal Detector
Fleury-Frenette, Karl ULg; Habraken, Serge ULg; Renotte, Yvon ULg et al

Patent (2009)

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See detailUnderstanding of optical readout accuracy with micromechanical sensor cantilever monitored by surface plasmon resonanc
Hastanin, Juriy ULg; Renotte, Yvon ULg; Fleury-Frenette, Karl ULg et al

in Optics Communications (2009), 282

This paper reports a concept of micromechanical sensing of environmental condition using the surface plasmon resonance phenomenon. We calculate the resolution in the cantilever bending monitoring using ... [more ▼]

This paper reports a concept of micromechanical sensing of environmental condition using the surface plasmon resonance phenomenon. We calculate the resolution in the cantilever bending monitoring using the transfer matrix numerical method. We show that the cantilever deflection can be monitored with a resolution in the nanometer range. The SPs resonance behavior of the multilayer stack in the case of gold cantilever is discussed. We believe that this concept permits a low cost and ease of fabrication for a large bi-dimensional array of sensors with an enhanced signal-to-noise ratio. [less ▲]

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See detailA gas micromechanical sensor based on surface plasmon resonance
Hastanin, Juriy ULg; Habraken, Serge ULg; Renotte, Yvon ULg et al

in Proceedings of SPIE (2008, October 02), 7116

We will present a new concept related to the micromechanical sensors for detecting the presence and concentration of chemical substances and/or biological organisms. A bi-dimensional array of micro ... [more ▼]

We will present a new concept related to the micromechanical sensors for detecting the presence and concentration of chemical substances and/or biological organisms. A bi-dimensional array of micro-cantilever coated by different types of sensing layer enables to identify a characteristic chemical composition of the gas in real-time mode. The selective molecular absorption by cantilever sensing layer will produce cantilever bending proportional to the concentration of molecules. To increase the gas sensor sensitivity, the SPR phenomenon is used for cantilever deflection monitoring. [less ▲]

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See detailLow Concentration Solar Array Experiment on-board PROBA-2
Ruelle, V.; Rossi, Laurence ULg; Thibert, Tanguy ULg et al

in Proceedings of the 8th Space Power Conference (2008, September)

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See detailA far infrared/terahertz micromechanical sensor based on surface plasmons resonance
Hastanin, Juriy ULg; Renotte, Yvon ULg; Fleury-Frenette, Karl ULg et al

in Proceedings of SPIE (2008), 7113

This paper describes a new concept related to the bolometric micromechanical sensors for detecting far IR and THz radiation. We believe that this concept permits a low cost and ease of fabrication of ... [more ▼]

This paper describes a new concept related to the bolometric micromechanical sensors for detecting far IR and THz radiation. We believe that this concept permits a low cost and ease of fabrication of large bi-dimensional array of sensors with an enhanced signal-to-noise ratio. The micromechanical sensor comprises a thermo-sensitive bi-material (multimaterial) micro-cantilever beam with a selective absorber dedicated to far IR and THz radiation energy, and optical readout system based on surface plasmon resonance for detecting the bending of the micro-cantilever element. To increase the radiation detector sensitivity, the SPR phenomenon is used for cantilever deflection monitoring. [less ▲]

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See detailSynthesis of adherent hydrophilic polypyrrole coatings onto (semi)conducting surfaces
Gabriel, Sabine ULg; Cecius, Michaël ULg; Fleury-Frenette, Karl ULg et al

in Chemistry of Materials (2007), 19(9), 2364-2371

Hydrophilic and adherent polypyrrole coatings were prepared by a two-step electrochemical method. First, alpha-pyrrole, omega-acrylate polyethylene oxide (Py-PEO-A) dual macromonomer was synthesized by ... [more ▼]

Hydrophilic and adherent polypyrrole coatings were prepared by a two-step electrochemical method. First, alpha-pyrrole, omega-acrylate polyethylene oxide (Py-PEO-A) dual macromonomer was synthesized by anionic polymerization and electrografted onto (semi)conducting substrates by cathodic polymerization of the acrylic end-group. The obtained adherent coating is hydrophilic and thus swells in water and bears a pyrrole ring, a precursor of the conducting polymer. In a second step, the coating is anodically polarized in a mixture of Py and Py-PEO to give the hydrophilic and adherent polypyrrole. Properties such as morphology, adherence, electroactivity, and hydrophilicity of these coatings were investigated by conventional methods and compared to those of pure polypyrrole coatings. These novel coatings exhibit efficient protein adsorption repellency and are thus good candidates for applications in biomaterials and biosensors. [less ▲]

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See detailPortable x-ray fluorescence spectrometer for coating thickness measurement
Carapelle, Alain ULg; Fleury-Frenette, Karl ULg; Collette, Jean-Paul ULg et al

in Review of Scientific Instruments (2007), 78(12),

A handheld x-ray spectrometer has been realized and tested. The purpose of the device is to measure the thickness of coated samples in the range of 1-1500 nm in an industrial environment. Accuracy of ... [more ▼]

A handheld x-ray spectrometer has been realized and tested. The purpose of the device is to measure the thickness of coated samples in the range of 1-1500 nm in an industrial environment. Accuracy of similar to 3% has been achieved in this range with a measurement time of 1 min. Automated software has been implemented to allow utilization by a nonspecialist operator. An automated calibration procedure, based on measurements of reference samples, is used. (C) 2007 American Institute of Physics. [less ▲]

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See detailRoughness evolution of some X-UV reflective materials induced by low energy (< 1 keV) ion beam milling
Gailly, Patrick ULg; Jamar, Claude ULg; Fleury-Frenette, Karl ULg et al

in Nuclear Instruments & Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms (2004), 216

Ion beam figuring (IBF) is an advanced technique that is been used for more than 10 years as a final step in the manufacturing of optical elements. It makes use of ion sputtering to correct shape defects ... [more ▼]

Ion beam figuring (IBF) is an advanced technique that is been used for more than 10 years as a final step in the manufacturing of optical elements. It makes use of ion sputtering to correct shape defects but this process may eventually lead to the degradation of the surface roughness. In this study, the evolution of roughness for some optical materials subjected to the ion beam figuring process has been investigated by using optical profilometry and scanning electron microscopy. Emphasis has been made on electroplated nickel, PVD gold and CVD silicon carbide. These materials are often used for X-ray and UV applications but only limited data on their behavior under ion milling is currently available. Roughness measurements have been performed at different etching depths down to 5 mum which is representative of typical IBF treatments. The effects of using different inert gases (Ar, Kr and Xe) with ion energies ranging from 200 to 900 eV have been studied. The observed trends are an important increase of the roughness for electroplated nickel, a slight decrease for PVD gold and a slight increase for CVD silicon carbide. Results are discussed in relation to previous related works and within sputtering considerations. (C) 2003 Elsevier B.V. All rights reserved. [less ▲]

Detailed reference viewed: 42 (3 ULg)