References of "Gailly, Patrick"
     in
Bookmark and Share    
Full Text
See detailLaser thermoreflectance for semiconductor thin films metrology
Gailly, Patrick ULg; Hastanin, Juriy ULg; Duterte, Charles et al

in Wehrspohn, R. B., Gombert, A (Ed.) Photonics for Solar Energy Systems IV (2012, June)

We present a thermoreflectance-based metrology concept applied to compound semiconductor thin films off-line characterization in the solar cells scribing process. The presented thermoreflectance setup has ... [more ▼]

We present a thermoreflectance-based metrology concept applied to compound semiconductor thin films off-line characterization in the solar cells scribing process. The presented thermoreflectance setup has been used to evaluate the thermal diffusivity of thin CdTe films and to measure eventual changes in the thermal properties of 5 μm CdTe films ablated by nano and picosecond laser pulses. The temperature response of the CdTe thin film to the nanosecond heating pulse has been numerically investigated using the finite-difference time-domain (FDTD) method. The computational and experimental results have been compared. [less ▲]

Detailed reference viewed: 34 (13 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 25 (5 ULg)
Full Text
See detailEtude de l’évolution de l’état de surface de matériaux optiques sous bombardement ionique à faible énergie
Gailly, Patrick ULg

Doctoral thesis (2011)

In this work the roughness and topography evolution of optical materials sputtered with low energy ion beam (≤1 keV) has been investigated. These materials (bulk or thin layer) are used in the ... [more ▼]

In this work the roughness and topography evolution of optical materials sputtered with low energy ion beam (≤1 keV) has been investigated. These materials (bulk or thin layer) are used in the manufacturing of mirrors for scientific (ground or space) instruments or for other optical applications. In the first part of the work, the roughness evolution of optical surfaces under sputtering has been investigated in the frame of the industrial process known as Ion Beam Figuring. This technique consists in removing shape errors on optical surfaces with a low energy ion beam (≤1 keV). One disadvantage of this process is a potential increase of roughness for surfaces under treatment. The roughness evolution of some materials relevant to the optical industry has been accurately characterized as function of etching depth down to 5 µm. These sputtering experiments have been carried out at normal incidence, mainly with argon ions (but also in a lesser extent with krypton and xenon ions), ion current density of ~1 mA/cm2 and ion beam energy ranging from 200 eV to 1000 eV. The roughness evolution under sputtering is low for materials with amorphous (glass, electroless nickel), monocrystalline (silicon) or even polycrystalline structure (CVD silicon carbide, PVD gold or nickel film), whereas it is considerably more important for some other metallic materials such as electroplated nickel and aluminium. This work has shown small differences in the roughness evolution of CVD silicon carbide as function of the ion beam energy. The roughness increase is faster at low ion energy (<500 eV) than at higher ion energy (650-1000 eV). The grain structure of this material is less revealed at higher energy, which is supposed to be due to a larger amorphization of the sputtered layer in this case. The influence of the ion mass on CVD silicon carbide and gold films on nickel substrates has been also illustrated. Our measurements have been also compared to scaling laws. Various growth and roughness exponents have been found, sometimes rather different from those foreseen by the KPZ equation. In the second part, we focus on periodically modulated structures (ripples) which developed on many solids when sputtered by an off-normal ion bombardment. In this work, we first observed these ripples on gold films deposited on electroplated nickel (materials used as reflective surfaces for X-ray space telescope) sputtered at grazing incidence. We studied the influence of sputtering parameters (ion beam incidence angle, energy and flux) on the characteristics of ripples induced on gold and silver thin film (~0.2 µm). Ion-induced ripples have also been observed on CdS, an interesting semiconductor crystal for optical applications. The ripples orientation and dimensions (spatial wavelengths from 0.13 µm to 0.29 µm) have been confronted to the Bradley-Harper (B-H) linear model. We used the SRIM software to evaluate the deposited energy and the surface tension coefficient distributions. Our results can be in great part explained by the current theories (Bradley-Harper, Makeev) on morphology of ion-sputtered surfaces. These results can be summarized hereunder: • Clear development of ripples for angle of incidence equal or higher than 60° on gold film and 70° on silver film. • In this work the ripples wave vector is always perpendicular to the ion beam direction for all angles, whereas the change in ripple orientation beyond a critical angle is usually reported in literature. This is a due to the different shape of the energy distribution function for our sputtering conditions. • Different regimes for roughness and topography evolution (grains, ripples) have been observed in function of the angle of incidence. 3 different areas can be distinguished, as predicted by Makeev non-linear model. • The diminution of ripple wavelength with ion energy shows that thermal diffusion is the main relaxation mechanism. [less ▲]

Detailed reference viewed: 173 (17 ULg)
Full Text
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 ▲]

Detailed reference viewed: 65 (14 ULg)
Full Text
See detailDEVELOPMENT OF COMPOSITE MATERIALS BASED ON A CARBON NANOTUBES NETWORK FOR SPACE APPLICATIONS
Gailly, Patrick ULg; Delhalle, Joseph; Garray, Didier et al

Conference (2010, October 01)

For few years, carbon nanotubes (CNTs) are added to in various materials. As CNTs have high mechanical, thermal and electrical properties, it is expected to boost by adding CNTs the performances of the ... [more ▼]

For few years, carbon nanotubes (CNTs) are added to in various materials. As CNTs have high mechanical, thermal and electrical properties, it is expected to boost by adding CNTs the performances of the matrix material. Usually carbon nanotubes are used as additive to an organic matrix and in small quantities, below 1 wt%. In this work we develop composite materials with high amount of CNT, based on a carbon nanotubes network. The main type of CNT network manufactured and tested is buckypaper obtained by filtration of CNTs dispersed in a liquid solution. Other CNT networks like 3D preformed shape and CNT arrays have been also investigated. The potential improvement brought by adding CNT network to conventional materials has been evaluated using the engineering rules established for composites. Hence, the maximal achievable material properties have been estimated. Using the previously described analysis, the potential of CNT reinforced composite for different space applications have been ranked. The mechanical (mainly for CNT fibre) and thermal driven applications seem the most promising ones, especially if specific properties are considered (due to the low density of CNTs). On the basis of this evaluation and manufacturing technologies available in our consortium, experimental efforts have been put on the optimization of the CNT network mainly for improving its thermal performances. Influence of the CNTs characteristics on the macroscopic buckypaper properties has been evaluated with CNTs of different morphology (MWNT, DWNT), length and functionalization. Several processes for manufacturing the buckypaper have been tried, using different solutions for CNTs dispersion (surfactant, water or ethanol), or applying alternative method like in-situ growth of CNTs on buckypapers. Among different CNT network post-treatment also tried, thermal treatment up to 2800°C has given the greatest improvement on the specific thermal conductivity. Eventually the CNT network is infiltrated by an organic (epoxy) or inorganic (aluminium) matrix to make the composite. 3D shape CNT network gives highly reinforced composite with 30wt% of CNTs. Even if current properties of CNT reinforced composite materials are not yet competitive with reference aerospace materials, improvement potential is large and manufacturing technologies are growing. [less ▲]

Detailed reference viewed: 50 (8 ULg)
Full Text
See detailIon beam figuring for precision optics
Gailly, Patrick ULg

E-print/Working paper (2008)

Detailed reference viewed: 4 (2 ULg)
Full Text
See detailMicro-usinage par laser excimère
Gailly, Patrick ULg

Learning material (2007)

Detailed reference viewed: 7 (1 ULg)
See detailLasers excimères: applications au micro-usinage
Gailly, Patrick ULg

Conference given outside the academic context (2006)

Detailed reference viewed: 3 (3 ULg)
Full Text
Peer Reviewed
See detailVolume phase holographic gratings: large size and high diffraction efficiency
Blanche, Pierre-Alexandre ULg; Gailly, Patrick ULg; Habraken, Serge ULg et al

in Optical Engineering (2004), 43(11), 2603-2612

Volume phase holographic gratings (VPHGs) possess unique properties that make them attractive for numerous applications. After reviewing major VPHG characteristics through theory, we discuss some aspects ... [more ▼]

Volume phase holographic gratings (VPHGs) possess unique properties that make them attractive for numerous applications. After reviewing major VPHG characteristics through theory, we discuss some aspects of the dichromated gelatin recording material and the holographic recording process. The large-scale VPHG research facility set up at the Center Spatial de Liege enables production of VPHGs up to 380 mm in diameter, with fringe frequencies from 315 to 3300 Ip/mm. We describe the work that has been undertaken in our laboratory to remove the last limitations inherent in VPHGs. (C) 2004 Society of Photo-Optical Instrumentation Engineers. [less ▲]

Detailed reference viewed: 40 (9 ULg)
Full Text
See detailION BEAM FIGURING OF CVD SILICON CARBIDE MIRRORS
Gailly, Patrick ULg

in Warmbein, B (Ed.) Proceedings of the 5th International Conference on Space Optics (ICSO 2004) (2004, March)

Optical and structural elements made of silicon carbide are increasingly found in space instruments. Chemical vapor deposited silicon carbide (CVD-SiC) is used as a reflective coating on SiC optics in ... [more ▼]

Optical and structural elements made of silicon carbide are increasingly found in space instruments. Chemical vapor deposited silicon carbide (CVD-SiC) is used as a reflective coating on SiC optics in reason of its good behavior under polishing. The advantage of applying ion beam figuring (IBF) to CVD-SiC over other surface figure-improving techniques is discussed herein. The results of an IBF sequence performed at the Centre Spatial de Liège on a 100 mm CVD-SiC mirror are reported. The process allowed to reduce the mirror surface errors from 243 nm to 13 nm rms . Beside the surface figure, roughness is another critical feature to consider in order to preserve the optical quality of CVD-SiC . Thus, experiments focusing on the evolution of roughness were performed in various ion beam etching conditions. The roughness of samples etched at different depths down to 3 m was determined with an optical profilometer. These measurements emphasize the importance of selecting the right combination of gas and beam energy to keep roughness at a low level. Kaufman-type ion sources are generally used to perform IBF but the performance of an end-Hall ion source in figuring CVD-SiC mirrors was also evaluated in this study. In order to do so, ion beam etching profiles obtained with the end-Hall source on CVD-SiC were measured and used as a basis for IBF simulations. [less ▲]

Detailed reference viewed: 99 (6 ULg)
Full Text
Peer Reviewed
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: 23 (3 ULg)
Full Text
See detailDevelopment of a metrology and figuring machine for large X-ray mirror
Gailly, Patrick ULg; de Chambure, Daniel; Collette, Jean Paul et al

Conference (2003, February 20)

To improve the image quality of X-ray replicated mirror, A new metrology machine has been built link to a ion beam figuring machine. The first one allows to accurately measure the shape of replicated X ... [more ▼]

To improve the image quality of X-ray replicated mirror, A new metrology machine has been built link to a ion beam figuring machine. The first one allows to accurately measure the shape of replicated X-ray mirrors. The machine is dedicated to cylindrical mirrors shape whose dimensions can vary from 50 to 800 mm in height and 600 to 800 mm in diameter. The present contribution will sum up the results achieved with this machine on an actual mirror. The machine calibration results and the data analysis to obtain the mirror final shape will be detailed. The final results are compared with other measurements performed by a traditional 3-D machine. The second one is a dedicated ion figuring machine dedicated for the figuring of the X-ray mirrors. The preliminary tests were undertaken to evaluate the ion figuring process on Nickel replicated surfaces. Those results were used to improve the design of the figuring machine, a detailed description of that machine follows. The reliability of the ion figuring process is shown through an actual problem. Finally, some leading remarks about the improvements of the ion figuring ion machine and the ion figuring process in general are drawn. [less ▲]

Detailed reference viewed: 15 (2 ULg)
Full Text
See detailNew process for X-ray mirror image quality improvement
Gailly, Patrick ULg; de Chambure, Daniel; Collette, Jean-Paul et al

in Freund, Andreas K. (Ed.) X-Ray Mirrors, Crystals, and Multilayers II (Proceedings Volume) (2002, December 24)

A new technique to improve the image quality of Ni replicated X-ray mirror is presented. During the manufacturing of XMM Mirror Module between 1994 to 1999, the classical manufacturing process showed its ... [more ▼]

A new technique to improve the image quality of Ni replicated X-ray mirror is presented. During the manufacturing of XMM Mirror Module between 1994 to 1999, the classical manufacturing process showed its limits. In 1995, the XMM Mirror Module Qualification Model HEW was around 20 arcsec. In 1998, the fifth Flight Model Mirror Module reached 11 arcsec HEW, with a single mirror shell achieving 8 arcsec HEW. The performance of this technology is namely limited by the integration process of the shells. The new technique is based on the following philosophy : • Firstly, an accurate measurement of each mirror shell after integration. A dedicated metrology system has been built and allows a precise metrology of the actual surface. • Secondly, a modification of the mirror shell and of the support to transfer the stress to a non optical active area. • Finally, an ion figuring run to correct the residual shape error of the mirror. The control and evaluation of the process is assured by EUV PSF assessment achieved in the FOCAL X facility developed for XMM. The advantages of this new process are to shape the mirrors in their final hardware configuration and the versality of the process enabling improvement of other kinds of high accuracy mirrors. [less ▲]

Detailed reference viewed: 17 (2 ULg)
Full Text
See detailFiguring sequences on a super-smooth sample
Tock, Jean-Philippe; Collette, Jean-Paul; Gailly, Patrick ULg et al

in Geyl, Roland; Maxwell, Jonathan (Eds.) Optical Fabrication and Testing, Proc. SPIE Volume: 3739 (1999, September 06)

An ion beam figuring facility is operational at the Centre Spatial de Liège since 1997. Its present capabilities are described. An extensive characterisation programme is running in order to determine the ... [more ▼]

An ion beam figuring facility is operational at the Centre Spatial de Liège since 1997. Its present capabilities are described. An extensive characterisation programme is running in order to determine the optimised parameters for various materials and operating conditions. In this frame, tests have been performed on a spherical gold-coated aluminium mirror plated in between with nickel. The nickel plating was used to be super-polished to a BRDF of 1 10-4 at 1 deg at 10 µm wavelength. Micro-roughness and etching rate measurements were realised and influence of ion bombardment on the coating has been established after removal of the gold coating. The gold coating removing was performed by using the ion beam flux. Finally, the mirror has been figured from the original sphere to a parabola. Surface characteristics evolution is also described in terms of micro-roughness and surface error. An overview of the research and development programmes related to this facility is given. Results of this technique and potential impact on optics fabrication are then briefly exposed. [less ▲]

Detailed reference viewed: 9 (4 ULg)
Full Text
See detailIon beam figuring of small BK7 and Zerodur optics : thermal effects
Gailly, Patrick ULg; Collette, Jean-Paul; Renson, Luc et al

in Geyl, Roland; Maxwell, Jonathan (Eds.) Optical Fabrication and Testing, Proc. SPIE Volume: 3739 (1999, September 06)

optics these last years. One of the disadvantages of ion figuring is the high surface temperature of the workpiece. Temperature aspects have already been mentioned by some authors but are weakly detailed ... [more ▼]

optics these last years. One of the disadvantages of ion figuring is the high surface temperature of the workpiece. Temperature aspects have already been mentioned by some authors but are weakly detailed. Therefore thermal effects on BK7 and Zerodur, mainly surface figure distortions and surface temperature measurements, have been investigated here in more detail. Distortion of the optical figure due to high temperature and temperature gradients induced by ion figuring is described. High figure distortion has been observed on 10 cm diameter BK7 samples. Distortions can also be observed on Zerodur samples (although much weaker). Differences between BK7 and Zerodur distortions are discussed. In order to analyse the nonuniform heating of the workpiece during ion bombardment, the surface temperature has been monitored with an infrared camera. Furthermore, surface temperature measurements with respect to ion beam parameters have also been performed. All these measurements show the necessity to care about thermal aspects during ion beam figuring for some sensible materials like BK7, but even for low expansion material like Zerodur. [less ▲]

Detailed reference viewed: 18 (1 ULg)
Full Text
See detailIon beam figuring of precision aspheric optical surfaces
Gailly, Patrick ULg; Collette, Jean-Paul; Tock, Jean-Philippe et al

Conference (1999)

An ion beam figuring facility is fully operational at the Centre Spatial de Liège since 1997. Ion beam figuring principle is briefly reminded and the present capabilities of the technique are described ... [more ▼]

An ion beam figuring facility is fully operational at the Centre Spatial de Liège since 1997. Ion beam figuring principle is briefly reminded and the present capabilities of the technique are described. An extensive characterisation programme is running in order to determine the optimised parameters for numerous materials and operating conditions. In this frame, tests have been performed on various optics to demonstrate the capability of the technique to figure aspheric shapes on glass or metallic substrates. At first, an aspherisation on a spherical gold-coated aluminium mirror plated in between with Nickel is presented. After removal of the gold coating with the ion beam, micro-roughness and etching rate measurements have been performed on the substrate material. Finally, the mirror has been figured from the original sphere to a parabola. The surface characteristics evolution is described in terms of micro-roughness and surface error. Other examples of complex aspherical figuring (polynomials of high order, ...) are shown. In conclusion, the potential impact and the results of this technique on optics fabrication, especially for exotic shapes, are exposed. The integration of the ion beam figuring process in a classical optics manufacturing sequence will be discussed, identifying the potential time and money savings. [less ▲]

Detailed reference viewed: 40 (1 ULg)