References of "Loicq, Jerôme"
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See detailClinically relevant optical properties of three types of intraocular lenses
Gatinel, Damien; Loicq, Jerôme ULg

Conference (2016, September)

Purpose: To experimentally compare the optical performance of three types of hydrophobic intraocular lenses (IOLs): extended depth of focus (TECNIS Symfony), bifocal (TECNIS ZMB00), and trifocal ... [more ▼]

Purpose: To experimentally compare the optical performance of three types of hydrophobic intraocular lenses (IOLs): extended depth of focus (TECNIS Symfony), bifocal (TECNIS ZMB00), and trifocal (FineVision GFree). Setting: Rothschild Foundation Paris, France - Liege Space Center Liège, Belgique Methods: Surface topography was analyzed by optical microscopy. Modulation transfer function (MTF) and spherical aberrations were determined on optical bench for variable pupil apertures and with two cornea models (0 µm and +0.28 µm). United States Air Force target imaging was analyzed for different focal points (near, intermediate, and far). Point spread function (PSF) and halos were quantified and compared. Results: All lenses presented step-like optic topography. For a pupil size of = 3 mm, distinctive MTF peaks were observed for all lenses: two peaks for the extended depth of focus and bifocal lenses with +1.75 and +4.00 diopters (D) addition, respectively, and three peaks for the trifocal lens with +1.75 and +3.50 addition for intermediate and near vision, respectively. The extended depth of focus and bifocal lens had slightly higher MTF at best focus with the +0.28 µm cornea model than with the 0 µm model, whereas the trifocal lens was likely to be more independent of the corneal spherical aberrations. Conclusions: Each lens appears to rely on light diffraction for optical performance, presenting halos with comparable intensities. For small pupil apertures, the MTF peaks for the far and intermediate focal distances of the trifocal and extended depth of focus lenses overlap, but the trifocal lens presented an additional MTF peak for the near focal points. [less ▲]

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See detailRefractive and diffractive contribution of linear chromatic aberration (LCA) on depth-of-focus with trifocal intraocular lenses (IOLs)
Loicq, Jerôme ULg; Gatinel, Damien

Poster (2016, September)

Purpose: To investigate the refractive and diffractive contribution of LCA on depth of focus extension of trifocal IOLs in polychromatic light conditions Setting: University of Liège, Belgium; Fondation ... [more ▼]

Purpose: To investigate the refractive and diffractive contribution of LCA on depth of focus extension of trifocal IOLs in polychromatic light conditions Setting: University of Liège, Belgium; Fondation Ophtalmologique A. de Rothschild, Paris Methods: The LCAs associated with the three focal points of hydrophobic and hydrophilic diffractive FineVision trifocal IOLs (PhysIOL SA, Liège, Belgium), were simulated in an Arizona eye model and experimentally measured on an optical bench at 480, 546 and 650 nm. The effect of Abbe number and aperture on different IOL materials was also evaluated. Based on wavelength–dependent MTF through-focus curves and PSF properties, polychromatic behavior of the trifocal IOLs was assessed under mesopic and photopic conditions. Results: LCA amplitude and sign were different for each of the trifocal IOL focal points. The diffractive LCA for near and intermediate was independent of IOL material (GFree versus hydrophilic acrylic, 26%), while far vision LCA appeared to be controlled by the material Abbe number. Under polychromatic conditions, the LCA contributed to depth of focus extension with different types of lens material, providing maximal visual acuity under white light conditions at all distances. Conclusions: Diffractive trifocal IOLs show chromatic aberrations with an increase in depth of focus under polychromatic light. This effect likely contributes to the extended range of vision. [less ▲]

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See detailConception of a near-IR spectrometer for ground-based observations of massive stars
Kintziger, Christian ULg; Desselle, Richard ULg; Loicq, Jerôme ULg et al

Poster (2016, June 27)

In our contribution, we outline the different steps in the design of a fiber-fed spectrographic instrument that intends to observe massive stars. Starting from the derivation of theoretical relationships ... [more ▼]

In our contribution, we outline the different steps in the design of a fiber-fed spectrographic instrument that intends to observe massive stars. Starting from the derivation of theoretical relationships from the scientific requirements and telescope characteristics, the entire optical design of the spectrograph is presented. Specific optical elements, such as a toroidal lens, are introduced to improve the instrument’s performances. Then, the verification of predicted optical performances is investigated through optical analyses such as resolution checking. Eventually, the star positioning system onto the central fiber core is explained. [less ▲]

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See detailVUV Optical Ground System Equipment and its application to the ICON FUV flight grating characterization and selection
Blain, Pascal ULg; Desselle, Richard ULg; Domken, Isabelle ULg et al

in Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation (2016, June)

ICON FUV is a two channel spectrographic imager that measures intensity and spatial distribution of oxygen (135.6 nm) and molecular nitrogen (157 nm) of the ionosphere. As those wavelengths are strongly ... [more ▼]

ICON FUV is a two channel spectrographic imager that measures intensity and spatial distribution of oxygen (135.6 nm) and molecular nitrogen (157 nm) of the ionosphere. As those wavelengths are strongly absorbed by the atmosphere, the optical elements of the system have to be tested inside vacuum chambers. Prior to the instrument alignment and calibration, two 3600 gr/mm gratings were characterized. The primary focus is the measurement of the diffraction efficiencies; while the second objective is to select the best grating and to define which is the flight and the spare. A dedicated setup has been developed to assess the grating optical performances under vacuum. A 1 cm diameter collimated beam is generated using an off-axis parabola and a UV source at its focal point. The grating is placed at the center of two rotation stages collinearly aligned. One detector is placed on a rotating arm, deported from its rotation center. A PMT detector records diffracted light intensity with respect to its angular position and its wavelength. Angular incidence on the grating is tuned with the help of the second rotation stage. The grating efficiency homogeneity and scattering properties are measured through a Y-X scan. [less ▲]

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See detailAlignment and calibration of the ICON-FUV instrument: Development of a vacuum UV facility
Loicq, Jerôme ULg; Blain, Pascal ULg; Kintziger, Christian ULg et al

in Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray (2016, June)

The optical calibration of the ICON-FUV instrument requires designing specific ground support equipment (GSE). The ICON-FUV instrument is a spectrographic imager that operates on two specific wavelengths ... [more ▼]

The optical calibration of the ICON-FUV instrument requires designing specific ground support equipment (GSE). The ICON-FUV instrument is a spectrographic imager that operates on two specific wavelengths in the UV (135.6 nm and 157 nm). All the operations have to be performed under vacuum UV light. The optical setup is based on a VUV monochromator coupled with a collimator that illuminates the FUV entrance slit. The instrument is placed on a manipulator providing fields pointing. Image quality and spectral properties can be then characterized for each field. OGSE, MGSE, optical calibration plan and vacuum alignment of the instrument are described. [less ▲]

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See detailOptical design and optical properties of a VUV spectrographic imager for ICON mission
Loicq, Jerôme ULg; Kintziger, Christian ULg; Mazzoli, Alexandra ULg et al

in Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray (2016, June)

In the frame of the ICON (Ionospheric Connection Explorer) mission of NASA led by UC Berkeley, CSL and SSL Berkeley have designed in cooperation a new Far UV spectro-imager. The instrument is based on a ... [more ▼]

In the frame of the ICON (Ionospheric Connection Explorer) mission of NASA led by UC Berkeley, CSL and SSL Berkeley have designed in cooperation a new Far UV spectro-imager. The instrument is based on a Czerny-Turner spectrograph coupled with two back imagers. The whole field of view covers [± 12° vertical, ± 9° horizontal]. The instrument is surmounted by a rotating mirror to adjust the horizontal field of view pointing by ± 30°. To meet the scientific imaging and spectral requirements the instrument has been optimized. The optimization philosophy and related analysis are presented in the present paper. PSF, distortion map and spectral properties are described. A tolerance study and alignment cases were performed to prove the instrument can be built and aligned. Finally straylight and out of band properties are discussed. [less ▲]

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See detailComparison of 3 Diffractive IOLs in 3 Wavelengths Bifocal/ EDOF/Trifocal.
Gatinel, Damien; Pagnoulle, Christophe; Loicq, Jerôme ULg et al

Conference (2016, May)

Purpose To describe the optical performances of 3 types of diffractive hydrophobic intraocular lenses (IOLs): monofocal achromatic, bifocal and trifocal, using various visible wavelengths. Methods 3 IOLs ... [more ▼]

Purpose To describe the optical performances of 3 types of diffractive hydrophobic intraocular lenses (IOLs): monofocal achromatic, bifocal and trifocal, using various visible wavelengths. Methods 3 IOLs were measured with an optical bench (PMTF,LambdaX,Nivelles, Belgium) to determine modulation transfer function (MTF) and point spread function (PSF). Measurements were performed at 480 nm,546 nm,650 nm using an aberration free cornea and aspheric artificial cornea generating +0.28µm positive spherical aberration by ISO11979-2 guidelines. Through-focus MTF was recorded for various pupil apertures. Evaluation of halos was performed from PSF measurements obtained at each focal spot location. Images of USAF targets were recorded with simulated distances from 1m to 25cm. Amplitude of off-axis peaks of radial profile of PSF enabled to quantify percentage of energy within the halos. Results The monofocal and the bifocal IOLs presented 2 peaks on the through-focus MTF in green light: intermediate vision (at +1.75D) for the monofocal achromatic lens, and far and near vision (at +4D) for the bifocal IOL of the same material. Three peaks (Distance, Intermediate at +1.75D, Near at +3.5D) were recorded with the trifocal IOL at any wavelength. The achromatic monofocal IOL was monofocal for far vision with red light and monofocal for near vision with blue light. The influence of the cornea models was limited. The amount of halos were comparable between lenses (3 to 5 % of the enclosed central light energy). Conclusion The achromatic diffractive IOL behaved like a bifocal IOL with an intermediate addition foci in green light. The bifocal and trifocal IOL induced similar chromatic effects for the near (bifocal, trifocal) and intermediate (trifocal) foci. [less ▲]

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See detailClinically Relevant Optical Properties of Bifocal, Trifocal, and Extended Depth of Focus Intraocular Lenses
Gatinel, Damien; Loicq, Jerôme ULg

in Journal of Refractive Surgery (2016), 32(4), 273-280

PURPOSE: To experimentally compare the optical performance of three types of hydrophobic intraocular lenses (IOLs): extended depth of focus, bifocal, and trifocal. METHODS: The tested IOLs were: TECNIS ... [more ▼]

PURPOSE: To experimentally compare the optical performance of three types of hydrophobic intraocular lenses (IOLs): extended depth of focus, bifocal, and trifocal. METHODS: The tested IOLs were: TECNIS ZMB00 (bifocal; Abbott Medical Optics, Abbott Park, IL), TECNIS Symfony ZXR00 (extended depth of focus; Abbott Medical Optics), and FineVision GFree hydrophobic (trifocal; PhysIOL, Liège, Belgium). Their surface topography was analyzed by optical microscopy. Modulation transfer function (MTF) and spherical aberrations were determined on optical bench for variable pupil apertures and with two cornea models (0 μm and +0.28 μm). United States Air Force target imaging was analyzed for different focal points (near, intermediate, and far). Point spread function (PSF) and halos were quantified and compared. RESULTS: The three lenses presented step-like optic topography. For a pupil size of 3 mm or greater, clearly distinctive MTF peaks were observed for all lenses: two peaks for the extended depth of focus and bifocal lenses with +1.75 and +4.00 diopters (D) addition, respectively, and three peaks for the trifocal lens with +1.75 and +3.50 addition for intermediate and near vision, respectively. The extended depth of focus and bifocal lens had slightly higher MTF at best focus with the +0.28 μm cornea model than with the 0 μm model, whereas the trifocal lens was likely to be more independent of the corneal spherical aberrations.CONCLUSIONS: It appears that the three lenses rely on light diffraction for their optical performance, presenting halos with comparable intensities. For small pupil apertures (< 3 mm), the MTF peaks for the far and intermediate focal distances of the trifocal and extended depth of focus lenses overlap, but the trifocal lens presented an additional MTF peak for the near focal points. [less ▲]

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See detailConception of a near-IR spectrometer for ground-based observations of massive stars
Kintziger, Christian ULg; Desselle, Richard ULg; Loicq, Jerôme ULg et al

in Proc. SPIE Volume 9908 Ground-based and Airborne Instrumentation for Astronomy VI (2016)

In our contribution, we outline the different steps in the design of a fiber-fed spectrographic instrument that intends to observe massive stars. Starting from the derivation of theoretical relationships ... [more ▼]

In our contribution, we outline the different steps in the design of a fiber-fed spectrographic instrument that intends to observe massive stars. Starting from the derivation of theoretical relationships from the scientific requirements and telescope characteristics, the entire optical design of the spectrograph is presented. Specific optical elements, such as a toroidal lens, are introduced to improve the instrument’s performances. Then, the verification of predicted optical performances is investigated through optical analyses such as resolution checking. Eventually, the star positioning system onto the central fiber core is explained. [less ▲]

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See detailComparison of 3 diffractive IOLs: one monofocal (achromatic), one bifocal and one trifocal lens implant
Gatinel, Damien; Loicq, Jerôme ULg; Pagnoule, Christophe et al

Conference (2015, September 08)

Purpose: To describe the optical performance of 3 types (monofocal, bifocal and trifocal) of diffractive hydrophobic intraocular lenses (IOLs). Setting: Fondation Rothschild, Paris, France Methods: An ... [more ▼]

Purpose: To describe the optical performance of 3 types (monofocal, bifocal and trifocal) of diffractive hydrophobic intraocular lenses (IOLs). Setting: Fondation Rothschild, Paris, France Methods: An achromatic monofocal, a bifocal and trifocal diffractive IOLs were measured with an optical bench, designed to measure Modulation transfer function (MTF) and point spread function (PSF) of diffractive intraocular lenses. The measurements were performed at 3 wavelengths (480 nm, 546 nm and 650 nm), using an aberration free cornea and an aspherical artificial cornea generating a +0.28 µm of positive spherical aberration (ISO 11979-2 guideline). The through-focus MTF was recorded with the 3 IOLs for various pupil apertures. The evaluation of the magnitude of the halos was performed from PSF measurement obtained at each focal spot location. Results: The monofocal and the two bifocal IOLs were presenting 2 peaks on the through-focus MTF in the green: for intermediate vision (at 1.75D) for the monofocal achromatic lens, and for far and for near vision( at +4D) for the bifocal IOL of the same material. Three peaks were recorded with the trifocal IOL at any wavelength. The achromatic monofocal was monofocal for far in the red and monofocal for near in the blue. The amount of energy allocated to each focal point was not very different for the three IOLs except for smaller apertures where the distance vision with the trifocal IOL had a significant lower peak than the two other IOLs. The amount of halos were comparable between lenses. Conclusions: The diffractive and refractive optics generated opposite chromatic aberration. A achromatic diffractive IOL behaves like a bifocal IOL with an intermediate addition The bifocal and trifocal IOL induce similar chromatic effects for the near (bifocal, trifocal) and intermediate (trifocal) foci. The tested diffractive patterns wee not efficient to correct the chromatic aberration at the distance foci for all tested IOLs. [less ▲]

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See detailProperties of a new hydrophobic diffractive trifocal intraocular lens: linear chromatic aberrations (LCA) by optical simulation and optical bench testing
Loicq, Jerôme ULg; Gatinel, Damien

Conference (2015, September 08)

Purpose: Impact of the IOL raw material Abbe number on diffractive trifocal optical outcomes in terms of light energy partition between the three foci, modulation transfer function (MTF) and linear ... [more ▼]

Purpose: Impact of the IOL raw material Abbe number on diffractive trifocal optical outcomes in terms of light energy partition between the three foci, modulation transfer function (MTF) and linear chromatic aberration (LCA). Setting: Space Center Liège (Centre Spatial de Liège), University of Liège, Liège, Belgium Methods: The difference between hydrophilic and hydrophobic materials doesn't rely on biocompatibility only, but also influence some optical properties. In order to highlight the impact of the raw material associated to Diffractive-Trifocal-IOLs, we compare certain optical properties of two Diffractive-Trifocal-IOLs associated to Physiol's Trifocal-technology and made of 26% hydrophilic and hydrophobic GF raw material. The Abbe number of the two IOL materials was measured with a refractometer. The through focus MTF curves at 3 wavelengths (480, 546 and 650 nm) and different apertures were generated by simulation in an Arizona eye model and compared with results on a PMTF optical bench. Results: The through focus MTF curves at the three wavelengths shows that the diffracted light for the near vision (+3.5 D) by the trifocal optic generates chromatic aberrations of opposite sign with respect to the refracted light assigned to the Far vision. The diffracted light at the origin of the Intermediate vision (+1.75 D) does not show significant amount of LCA and can be considered as a chromatic aberration free focus. Results are similar for the two lens materials. Conclusions: Diffractive Trifocal IOLs show chromatic aberrations whose sign and amplitude depend on the add-power of the different foci (far, near or intermediate), but is basically independent of the nature of the type of raw material, hydrophilic or hydrophobic. [less ▲]

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See detailOptical study of diffraction grating/Fresnel lens combinations applied to a spectral-splitting solar concentrator for space applications
Michel, Céline ULg; Loicq, Jerôme ULg; Thibert, Tanguy ULg et al

in Applied Optics (2015), 54(22), 6666-6673

This paper presents a new design of a planar solar concentrator with spectral splitting of light for space applications. This concentrator spectrally splits the incident light into mainly two parts. Each ... [more ▼]

This paper presents a new design of a planar solar concentrator with spectral splitting of light for space applications. This concentrator spectrally splits the incident light into mainly two parts. Each part is then focused onto specific spatially separated photovoltaic cells, allowing for independent control of respective cells output power. These advantages of both spectral splitting and light focusing are here combined thanks to a specific diffraction grating superimposed on a Fresnel lens. The theoretical principle of the optical design is presented, with optimization of each element and improvement steps, including optimization of grating period evolution along the lens, and testing of two kinds of gratings (a blazed and a lamellar one). First numerical results are presented, highlighting the possibility to design a concentrator at about 10× or more for each cell, with an output power larger than that of a classical concentrator focusing on a GaAs SJ cell, and less than 10% of losses for tracking errors up to ±0.8°. Some experimental results are also presented. [less ▲]

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See detailOptical Study of a Spectrum Splitting Solar Concentrator based on a Combination of a Diffraction Grating and a Fresnel Lens
Michel, Céline ULg; Loicq, Jerôme ULg; Thibert, Tanguy ULg et al

Poster (2015, April 14)

This poster presents recent improvements of our new solar concentrator design for space application. The concentrator is based on a combination of a diffraction grating (blazed or lamellar) coupled with a ... [more ▼]

This poster presents recent improvements of our new solar concentrator design for space application. The concentrator is based on a combination of a diffraction grating (blazed or lamellar) coupled with a Fresnel lens. Thanks to this diffractive/refractive combination, this optical element splits spatially and spectrally the light and focus approximately respectively visible light and IR light onto electrically independent specific cells. It avoid the use of MJs cells and then also their limitations like current matching and lattice matching conditions, leading theoretically to a more tolerant system. The concept is reminded, with recent optimizations, ideal and more realistic results, and the description of an experimental realization highlighting the feasibility of the concept, and the closeness of theoretical and experimental results. [less ▲]

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See detailCalibration and testing of wide-field UV instruments
Frey, Harald; Mende, Stephen; Loicq, Jerôme ULg et al

Conference (2015, April)

As with all optical systems the calibration of wide-field ultraviolet systems includes three main areas: sensitivity, imaging quality, and imaging capability. The one thing that makes these calibrations ... [more ▼]

As with all optical systems the calibration of wide-field ultraviolet systems includes three main areas: sensitivity, imaging quality, and imaging capability. The one thing that makes these calibrations difficult is the need for working in vacuum substantially extending the required time and effort compared to visible systems. In theory a ray tracing and characterization of each individual component of the optical system (mirrors, windows, grating) should provide the transmission efficiency of the combined system but potential unknown effects (contamination, misalignment, measurement errors) will make the final error too large for most applications. Therefore it is desirable to test and measure the optical properties of the whole system in vacuum and compare the overall response to the response of a calibrated photon detector. Based on the experience with the IMAGE Spectrographic Imager (SI) and Wide-band Imaging Camera (WIC), and the ICON-FUV instrument we will discuss the steps and procedures for the proper radiometric sensitivity and pass-band calibration, spot size, imaging distortions, flat field and field of view determination. [less ▲]

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See detailICON FUV Imager
Mende, Stephen; Chou, Cathy; Loicq, Jerôme ULg et al

Conference (2015, April)

A novel design FUV spectrographic imager is currently under construction at UC Berkeley for the payload of the Ionospheric Connection Explorer (ICON). This instrument will image the limb-view atmosphere ... [more ▼]

A novel design FUV spectrographic imager is currently under construction at UC Berkeley for the payload of the Ionospheric Connection Explorer (ICON). This instrument will image the limb-view atmosphere/ionosphere with a FOV of 24x18 degrees (vertical and horizontal) tilted down by 20⁰ and looking in a direction nominally perpendicular to the spacecraft velocity. From the spacecraft altitude (575 km) the view provides coverage from sub-limb up to ~500 km limb tangent height. There is a steering mirror assembly that allows steering the view ±30⁰ with respect to the nominal direction in order to observe the nightglow emissions along the local magnetic meridian. The instrument uses the spectrographic imager principle first used on the IMAGE spacecraft in which several full two-dimensional instantaneous images are formed in specific wavelength bands. One of the two bands on ICON contains the 135.6 nm atomic oxygen emission while the other band covers the N2 LBH emission region near 157 nm. When the imager is viewing the sunlit atmosphere the instrument provides the limb altitude profile of the atmospheric O/N2 ratio. On the night side the instrument observes the 135.6 nm emission that is produced by the recombination of O+ and therefore provides a good proxy for the nighttime ionospheric density. To minimize data downlink, 6 parallel vertical stripe segments will be transmitted to the ground from both channels every 12 seconds. In addition the nighttime 135.6 nm data will be integrated as two dimensional (spacecraft orbit latitude and longitude) maps. One map is projected on a sphere at 300 km altitude while the other map projects at a surface defined by the tangent height of observation from the ICON satellite. Both maps will be integrated with motion compensation to minimize blurring due to the satellite motion. [less ▲]

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See detailOptical Study of a Spectrum Splitting Solar Concentrator based on a Combination of a Diffraction Grating and a Fresnel Lens
Michel, Céline ULg; Loicq, Jerôme ULg; Thibert, Tanguy ULg et al

in AIP Conference Proceedings (2015), 1679

This paper presents recent improvements of our new solar concentrator design for space application. The concentrator is based on a combination of a diffraction grating (blazed or lamellar) coupled with a ... [more ▼]

This paper presents recent improvements of our new solar concentrator design for space application. The concentrator is based on a combination of a diffraction grating (blazed or lamellar) coupled with a Fresnel lens. Thanks to this diffractive/refractive combination, this optical element splits spatially and spectrally the light and focus approximately respectively visible light and IR light onto electrically independent specific cells. It avoid the use of MJs cells and then also their limitations like current matching and lattice matching conditions, leading theoretically to a more tolerant system. The concept is reminded, with recent optimizations, ideal and more realistic results, and the description of an experimental realization highlighting the feasibility of the concept and the closeness of theoretical and experimental results. [less ▲]

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See detailInvestigation of spectral impacts on the performance of a concentration device using a Fresnel lens combined with a double junction cell
Loicq, Jerôme ULg; Galante, Nicolas ULg; Thibert, Tanguy ULg et al

in Proceedings of SPIE (2014, May 15)

This experimental study was carried out within the context of high concentration photovoltaics. The paper presents the results of an experimental investigation relating to the quantification of the ... [more ▼]

This experimental study was carried out within the context of high concentration photovoltaics. The paper presents the results of an experimental investigation relating to the quantification of the impacts of the chromatic effect on the performance of a double junction GaInP/GaAs solar cell. Chromatic effects are the result of material dispersion caused by the refractive optics component. This study aims to evaluate the effect of the spectral modification of the incident beam on the whole solar concentrator system performance. Such considerations are fundamental in producing a highly accurate design, with which to achieve the best possible system performance. Efficiency is evaluated within the vicinity of the focus of a Fresnel lens designed for concentration. On the optical axis, rays with different wavelengths are not focalized at the same points. The spectral content of the beam depends, therefore, upon the position of the cell along the optical axis. It is assumed that spectral content modification may have an impact on cell performance and, as a consequence, on system efficiency as a whole. Efficiency of the optical Fresnel lens and of the cell were evaluated in relation to spectral content modification. [less ▲]

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See detailSpectral splitting planar solar concentrator : Design and Experimental testing Preliminary results
Blain, Pascal ULg; Michel, Céline ULg; Clermont, Lionel ULg et al

in Proceedings of SPIE (2014, May 15), 9140

We present a new concept in solar concentrator: spectral splitting. It implies reflective, refractive and diffractive elements that allow two spectrally differentiated beams to reach different and/or ... [more ▼]

We present a new concept in solar concentrator: spectral splitting. It implies reflective, refractive and diffractive elements that allow two spectrally differentiated beams to reach different and/or unmatched lattice solar cells. Those cells efficiencies are then enhanced. The aimed geometrical concentration factor is 5× and the theoretical optical efficiency of that concentrator concept reaches 82%. [less ▲]

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See detailComparison of off-axis TMA and FMA telescopes optimized over different fields of view: applications to Earth observation
Clermont, Lionel ULg; Stockman, Yvan ULg; Dierckx, Wouter et al

in Proceedings of SPIE (2014, May 01), 9131

TMA, or three mirror anastigmats, have already been used successfully for various space missions. In the frame of earth observation, ProbaV satellite uses 3 TMAs to cover a total 102.4° field-of-view ... [more ▼]

TMA, or three mirror anastigmats, have already been used successfully for various space missions. In the frame of earth observation, ProbaV satellite uses 3 TMAs to cover a total 102.4° field-of-view; ground sampling distance is about 100m at the center of field-of view and 370m at the edge. For future earth observation missions, the goal would be to reach 100m spatial resolution all over the 102.4° FOV. This would require to up-scale optical specifications, thus increasing geometrical aberrations. FMA, or four mirror anastigmats, could thus be a good candidate for future missions, as a fourth mirror would allow better correction of optical aberrations. In this work, TMA and FMA have been optimized over different fields-of view. Performance limitations are then derived, which show that FMA seems promising for future missions. Radiometry aspects are discussed and preliminary tolerance analysis is carried out. [less ▲]

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See detailStudy of a solar concentrator for space based on a diffractive/refractive optical combination
Michel, Céline ULg; Loicq, Jerôme ULg; Thibert, Tanguy ULg et al

Conference (2014, April 16)

The present work proposes a theoretical optical study of a new planar solar concentrator for space applications. The concentrator focuses light onto three spatially separated photovoltaic cells (three ... [more ▼]

The present work proposes a theoretical optical study of a new planar solar concentrator for space applications. The concentrator focuses light onto three spatially separated photovoltaic cells (three single-junctions, dedicated to two different light spectra), allowing for independent control of the output power of each cell. The design, based on a blazed diffraction grating superimposed on a Fresnel lens, combines advantages of both spectral splitting and light focusing. Theoretical model and optimization of the optical design are presented, including the variation of the grating period along the lens. Numerical results are detailed, highlighting the possibility to design a concentrator at more than 10× for each cell, with an optical efficiency of ~71% and less than 10% of losses for tracking errors < ±0.85°. A thermal study completes the work, as well as a first theoretical comparison with a planar Fresnel based solar concentrator focusing on a GaAs cell. [less ▲]

Detailed reference viewed: 34 (18 ULg)