References of "Loicq, Jerôme"
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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 detailExperimental Results of Hybrid and Refractive Achromatic Doublets Made of PC and PMMA
Languy, Fabian ULg; Lenaerts, Cedric ULg; Loicq, Jerôme ULg et al

Conference (2012)

To combine achromatic system with cost-effective technology, we propose the use or hybride (refractive/diffractive) and refractive doublets Fresnel lenses. These two technologies have been compared ... [more ▼]

To combine achromatic system with cost-effective technology, we propose the use or hybride (refractive/diffractive) and refractive doublets Fresnel lenses. These two technologies have been compared experimentally from an optical point of view [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 detailVérification expérimentale de modèles opto-thermo-élastiques simulés avec le logiciel OOFELIE Multiphysics
Mazzoli, Alexandra ULg; Saint-Georges, Philippe; Orban, Anne ULg et al

in 12ème colloque international francophone sur les Méthodes et Techniques Optiques pour l'Industrie (2011, November)

Detailed reference viewed: 43 (8 ULg)
See detailUne histoire de la lumière
Loicq, Jerôme ULg

Conference given outside the academic context (2011)

De l’aube au crépuscule Le jour les couleurs sont couleurs, la nuit que deviennent-elles ? A l’aube, les premiers rayons de soleils pointent leur nez. Ils nous arrivent de l’espace, de notre étoile la ... [more ▼]

De l’aube au crépuscule Le jour les couleurs sont couleurs, la nuit que deviennent-elles ? A l’aube, les premiers rayons de soleils pointent leur nez. Ils nous arrivent de l’espace, de notre étoile la plus proche, le soleil. La nuit d’autres rayons nous sont visibles. Sont-ils déjà présent lorsque notre étoile brille ? Les rayons du soleil nous procurent une sensation de chaleur, ils nous éblouissent aussi. Parfois ils rencontrent des goutes de pluie et se dispersent en un spectacle coloré. Qui sont-ils ces rayons de lumière? La lumière est à la fois si familière et en même temps si complexe. Le paradoxe est que notre savoir et notre compréhension de celle-ci ne passe que par son interaction avec la matière. Si nous voyons la lumière c’est parce qu’elle interagit avec notre œil. Aussi il existe des lumières que nous ne voyons pas parce que notre œil n’y est simplement pas sensible. Donc la lumière : La lumière est une onde qui se propage en ligne droite. Par opposition à une onde sonore, la lumière n’a pas besoin de support pour se propager. Elle peut voyager dans le vide, seul son champ électrique associé à son champ magnétique tous deux oscillants sont suffisants pour la faire parcourir des dizaines, des milliers, des millions,… d’années lumière à la vitesse… de la lumière. Cette vitesse réputée inaccessible sauf par la lumière elle-même. Aucune particule massive ne peut atteindre cette vitesse, pourtant finie. Nous avons dit que la lumière est une onde, c’est vrai ! Enfin, c’est une modélisation de ce phénomène. Dans certaines théories, on parle de corpuscule, de quantum d’énergie. La lumière est duale. Tout comme la matière en fait. La lumière « émise » par la terre transporte aussi vers l’univers la trace de la vie sur notre planète. Où en est-on dans sa connaissance ? Dans ces conférences, je voudrais vous parler de la lumière et de ses interactions ; faire avec vous l’état des connaissances actuelles ; vous emmener dans un monde particulier, un monde où la lumière rencontre une aile de papillon. [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 detailLarge white organic light-emitting diode lighting panel on metal foils
Guaino, Philippe; Mazeri, Fabrizo; Hofmann, Michael et al

in Journal of Photonics for Energy [=JPE] (2011), 1

Large-area top-emitting PIN structure (highly p- and n- type doped transport layers for electrons and holes and an undoped emitter layer)–organic light-emitting diode (OLED) on advanced metal foils were ... [more ▼]

Large-area top-emitting PIN structure (highly p- and n- type doped transport layers for electrons and holes and an undoped emitter layer)–organic light-emitting diode (OLED) on advanced metal foils were fabricated for lighting applications. ArcelorMittal has developed a new surface treatment on metal foils, suitable for roll-to-roll production and dedicated to large-area device integration. Both monochromatic and white devices are realized on advanced metal foils. Power efficiencies at 1000 cd/m2 of >70 lm/W (green), moreover, power efficiency of white devices of >22 lm/W are achieved. Furthermore, first large-area 60 × 60 cm white OLED sources on metal foils are presented. [less ▲]

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See detailExperimental validation of opto-thermo-elastic modeling in OOFELIE Multiphysics
Mazzoli, Alexandra ULg; Saint-Georges, Philippe; Orban, Anne ULg et al

in SPIE, Optical Systems Design (Marseille 5-8 septembre 2011) (2011)

The objective of this work is to demonstrate the correlation between a simple laboratory test bench case and the predictions of the Oofelie MultiPhysics software in order to deduce modelling guidelines ... [more ▼]

The objective of this work is to demonstrate the correlation between a simple laboratory test bench case and the predictions of the Oofelie MultiPhysics software in order to deduce modelling guidelines and improvements. For that purpose two optical systems have been analysed. The first one is a spherical lens fixed in an aluminium barrel, which is the simplest structure found in an optomechanical system. In this study, material characteristics are assumed to be well known: BK7 and aluminium have been retained. Temperature variations between 0 and +60°C from ambient have been applied to the samples. The second system is a YAG laser bar heated by means of a dedicated oven. For the two test benches thermo-elastic distortions have been measured using a Fizeau interferometer. This sensor measures wavefront error in the range of 20 nm to 1 μm without physical contact with the optomechanical system. For the YAG bar birefringence and polarization measurements have also been performed using a polarimetric bench. The tests results have been compared to the predictions obtained by Oofelie MultiPhysics which is a multiphysics toolkit treating coupled problems of optics, mechanics, thermal physics, electricity, electromagnetism, acoustics and hydrodynamics. From this comparison modelling guidelines have been issued with the aim of improving the accuracy of computed thermo-elastic distortions and their impact on the optical performances. [less ▲]

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See detailContinuous Solar Simulator for Concentrator Photovoltaic Systems
Thibert, Tanguy ULg; Hellin, Marie-Laure ULg; Loicq, Jerôme ULg et al

in Proceedings of the 25th European Photovoltaic Solar Energy Conference (2010, September)

A continuous solar simulator for measuring performance of concentrator photovoltaic (CPV) systems is presented. The illumination system is based on a Xenon lamp, a homogenizer rod, shaping optics and a ... [more ▼]

A continuous solar simulator for measuring performance of concentrator photovoltaic (CPV) systems is presented. The illumination system is based on a Xenon lamp, a homogenizer rod, shaping optics and a 30cm diameter collimator. The design optimises the reproduction of the characteristics of direct solar illumination: 32’ divergence, high spatial homogeneity, sun-like spectral distribution, with a maximum intensity of 250W/m². It accommodates pass-band and attenuation filters to tune the beam output. It operates in continuous mode, allowing to investigate CPV thermal aspects as well. The present paper addresses the concept design of the solar simulator and associated performance results. [less ▲]

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See detailAchromatization of solar concentrator using diffractive optics
Languy, Fabian ULg; Lenaerts, Cedric ULg; Loicq, Jerôme ULg et al

Poster (2009)

Photovoltaic energy suffers from payback time. High solar concentration (above 500 suns) is a very interesting way to reduce production cost. The use of lenses allows more flexibility to make light flux ... [more ▼]

Photovoltaic energy suffers from payback time. High solar concentration (above 500 suns) is a very interesting way to reduce production cost. The use of lenses allows more flexibility to make light flux more uniform. In addition lenses are less prone to errors of manufacture and can be easily duplicated. Unfortunately, optical materials are very dependent on the wavelength which causes important chromatic aberrations. One can think about achromatic doublets but doublets are thick, heavy and require exotic glasses which make them expensive. During the conference, I would like to present an innovative way to achromatize solar concentrators using hybrid (refractive/diffractive) lenses. Indeed, an hybrid lens is as thin as a Fresnel lens and is made in only one glass. But diffractive lenses suffer from limited broadband diffraction efficiency due to spurious orders. To overcome the lake of efficiency we are investigating the use of multi-layer diffractive optical element. This technique allows to achieve an efficiency greater than 97% over the full visible spectrum using only three components (e.g. two optical elements + air). [less ▲]

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See detailAchromatization of solar concentrator thanks to diffractive optics
Languy, Fabian ULg; Lenaerts, Cedric ULg; Loicq, Jerôme ULg et al

Conference (2009)

Refractive solar concentrators suffer from important chromatic aberration. To enhance solar cell performance and increase the concentrating ratio, we propose an hybrid (diffractive/refractive) lens which ... [more ▼]

Refractive solar concentrators suffer from important chromatic aberration. To enhance solar cell performance and increase the concentrating ratio, we propose an hybrid (diffractive/refractive) lens which allows a more uniform flux density and an achromatized (in the sense of achromatic doublet) illumination of the cell. To solve the problem of high diffraction efficiency, we turn to multilayer diffractive lenses to have broadband high diffraction efficiency optimized on solar spectrum. Rigorous coupled wave analysis simulations were performed in order to check the validity of scalar theory, they led to a new order of magnitude for the ratio period/wavelength which has been found to be around 100 in place of 10. [less ▲]

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See detailHybrid wetting state on micro-waffle textures
Caps, Hervé ULg; Vandormael, Denis; Loicq, Jerôme ULg et al

in Europhysics Letters (2009), 88

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See detailMicro-technology for space mission
Loicq, Jerôme ULg

Conference (2007, October 03)

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See detailAdaptation of photorefractive holographic camera for observation of micro-mechanical structures
Georges, Marc ULg; Thizy, Cédric ULg; Loicq, Jerôme ULg et al

in Hesselink, L.; Feinberg, J. (Eds.) Controlling Light with Light: Photorefractive Effects, Photosensitivity, Fiber Gratings, Photonic Materials and More (PR07) (2007, October)

The photorefractive holographic camera initially working on large scattering objects has been adapted to observe centimetric to micrometric objects. Application on micro-mechanical systems is presented

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See detailFresnel rhombs as achromatic phase shifters for infrared nulling interferometry
Mawet, D.; Hanot, Charles ULg; Lenaers, C. et al

in Optics Express (2007), 15

We propose a new family of achromatic phase shifters for infrared nulling interferometry. These key optical components can be seen as optimized Fresnel rhombs, using the total internal reflection ... [more ▼]

We propose a new family of achromatic phase shifters for infrared nulling interferometry. These key optical components can be seen as optimized Fresnel rhombs, using the total internal reflection phenomenon, modulated or not. The total internal reflection indeed comes with a phase shift between the polarization components of the incident light. We propose a solution to implement this vectorial phase shift between interferometer arms to provide the destructive interference process needed to disentangle highly contrasted objects from one another. We also show that, modulating the index transition at the total internal reflection interface allows compensating for the intrinsic material dispersion in order to make the subsequent phase shift achromatic over especially broad bands. The modulation can be induced by a thin film of a well-chosen material or a subwavelength grating whose structural parameters are thoroughly optimized. We present results from theoretical simulations! together with preliminary fabrication outcomes and measurements for a prototype in Zinc Selenide. [less ▲]

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See detailFresnel rhombs as achromatic phase shifters for infrared nulling interferometry: first experimental results
Hanot, Charles ULg; Mawet, D.; Loicq, Jerôme ULg et al

in Coulter, Daniel R (Ed.) "Techniques and Instrumentation for Detection of Exoplanets III" Proceedings of the SPIE, Volume 6693, Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (2007, September 01)

One of the most critical units of nulling interferometers is the Achromatic Phase Shifter. The concept we propose here is based on optimized Fresnel rhombs, using the total internal reflection phenomenon ... [more ▼]

One of the most critical units of nulling interferometers is the Achromatic Phase Shifter. The concept we propose here is based on optimized Fresnel rhombs, using the total internal reflection phenomenon, modulated or not. The total internal reflection induces a phase shift between the polarization components of the incident light. We present the principles, the current status of the prototype manufacturing and testing operations, as well as preliminary experiments on a ZnSe Fresnel rhomb in the visible that have led to a first error source assessment study. Thanks to these first experimental results using a simple polarimeter arrangement, we have identified the bulk scattering as being the main error source. Fortunately, we have experimentally verified that the scattering can be mitigated using spatial filters and does not decrease the phase shifting capabilities of the ZnSe Fresnel rhomb. [less ▲]

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See detailThe annular groove phase mask coronagraph: an achromatic optical vortex
Mawet, D.; Riaud, Pierre ULg; Hanot, Charles ULg et al

in Coulter, Daniel R (Ed.) "Techniques and Instrumentation for Detection of Exoplanets III" Proceedings of the SPIE, Volume 6693, Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (2007, September 01)

The Annular Groove Phase Mask coronagraph (AGPM) is an intrinsically achromatic vectorial vortex. It consists of integrated subwavelength optical elements whose space-variant polarization properties can ... [more ▼]

The Annular Groove Phase Mask coronagraph (AGPM) is an intrinsically achromatic vectorial vortex. It consists of integrated subwavelength optical elements whose space-variant polarization properties can be engineered and optimized to synthesize one of the theoretically most efficient coronagraphs. This paper briefly recalls the principles of the AGPM, presents the benefit of its implementation inside a polarimetric differential imager, realistic numerical simulations assessing its performances, as well as the current status of the near-infrared and visible prototype manufacturing operations. [less ▲]

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See detailQuantitative accelerated life testing of MEMS accelerometers
Bazu, Marius; Gălăţeanu, Lucian; Ilian, Virgil Emil et al

in sensors (2007), 7(11), 2846

Quantitative Accelerated Life Testing (QALT) is a solution for assessing the reliability of Micro Electro Mechanical Systems (MEMS). A procedure for QALT is shown in this paper and an attempt to assess ... [more ▼]

Quantitative Accelerated Life Testing (QALT) is a solution for assessing the reliability of Micro Electro Mechanical Systems (MEMS). A procedure for QALT is shown in this paper and an attempt to assess the reliability level for a batch of MEMS accelerometers is reported. The testing plan is application-driven and contains combined tests: thermal (high temperature) and mechanical stress. Two variants of mechanical stress are used: vibration (at a fixed frequency) and tilting. Original equipment for testing at tilting and high temperature is used. Tilting is appropriate as application-driven stress, because the tilt movement is a natural environment for devices used for automotive and aerospace applications. Also, tilting is used by MEMS accelerometers for anti-theft systems. The test results demonstrated the excellent reliability of the studied devices, the failure rate in the “worst case” being smaller than 10-7h-1. [less ▲]

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See detailRELIABILITY ACCELERATED TESTING OF MEMS ACCCELEROMETERS
Bazu, Marius; Gălăţeanu, Lucian; Ilian, Virgil Emil et al

in IEEE Sensors Journal (2007), 1

An attempt to assess the reliability of a batch of MEMS accelerometers is presented. The testing plan is application oriented and contains combined tests: thermal and mechanical stresses (two variants ... [more ▼]

An attempt to assess the reliability of a batch of MEMS accelerometers is presented. The testing plan is application oriented and contains combined tests: thermal and mechanical stresses (two variants: vibration and tilting) were used. The results demonstrated the good reliability of the tested device, the failure rate being smaller than 6.10-8h-1. [less ▲]

Detailed reference viewed: 38 (3 ULg)