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Saint-Étienne, France

Pietroy D.,CNRS Hubert Curien Laboratory | Di Maio Y.,CNRS Hubert Curien Laboratory | Moine B.,CNRS Hubert Curien Laboratory | Baubeau E.,Impulsion SAS | Audouard E.,CNRS Hubert Curien Laboratory
Optics Express | Year: 2012

Precise weight measurements of stainless steel, PZT and PMMA samples were performed after groove machining with femtosecond laser pulses (150 fs, 800 nm, 5 kHz) to determine volume ablation rates and ablation threshold with good accuracy. Weighing clearly enables faster determination of such phenomenological parameters without any methodological issue compared to other methods. Comparisons of the three types of materials reveal similar monotonous trends depending on peak fluences from 0.2 to 15 J/cm2. The metallic target exhibits both the lowest volume ablation rate under the highest irradiation conditions with almost 400 μm3/pulse and the lowest ablation threshold with 0.13 J/cm2. Ceramic PZT reaches 3.103 μm3/pulse with a threshold fluence of 0.26 J/cm2 while polymer PMMA attains 104 μm3/pulse for a 0.76 J/cm 2 threshold. Pros and cons of this method are also deduced from complementary results obtained on microscopic and confocal characterizations. © 2012 Optical Society of America.

Mauclair C.,CNRS Hubert Curien Laboratory | Landon S.,Qiova | Pietroy D.,CNRS Hubert Curien Laboratory | Baubeau E.,Impulsion SAS | And 2 more authors.
Journal of Laser Micro Nanoengineering | Year: 2013

Femtosecond laser processing enables the machining of micro-grooves by translating the focused femtosecond beam on the sample surface. Most of the time, the spatial intensity distribution on the sample is nearly Gaussian with a circular symmetry. The micro-grooves machined this way show "classic" cross sectional profile with a "v" shape. We present here a technique to modulate the cross sectional profile of the micro-grooves in a single laser scan. The technique relies on advanced spatial beam shaping where the intensity distribution is designed to spatially modulate the pulse overlapping during the scanning process. The corresponding exposure gradient enables to control the cross sectional profile of the micro groove. We present machining results on stainless steel using ultrashort pulses (120fs, 800nm at a repetition rate of 5kHz) where calculations based on the ablation rate clearly match the cross sectional profile of the machined micro grooves.

Bernard A.,Jean Monnet University | Bernard A.,Impulsion SAS | Audouard E.,University of Lyon | Audouard E.,Impulsion SAS | And 8 more authors.
Journal of Laser Micro Nanoengineering | Year: 2012

Femtosecond laser (FL) has become a common tool in corneal surgery during the last years. The first clinical application of FL in ophthalmology was in refractive surgery for the cutting of su-perficial cornea flaps in transparent corneas. Recently, FL applications have been extended to pene-trating and anterior or posterior lamellar corneal grafts. However, commercially available FL in ophthalmology have already shown limitations in these new applications, particularly in oedema-tous cornea (secondary to corneal diseases or occurring during storage by eye banks) that cause light scattering during stromal crossing. In order to improve these cuts, knowledge on the biological ma-terial, namely corneal stroma, is essential. Moreover, collagen organization of anterior corneal stro-ma is more compact compared to the posterior one, but the influence of these structural differences on the cut has never been studied. In this work, we compared ablation rates (ARs) in anterior and posterior human corneal stroma, isolated from the rest of the cornea by mechanical dissection in or-der to eliminate the scattering effect. ARs were quantified using Second Harmonic Generation mi-croscopy. Results showed significantly higher ARs in posterior corneal stroma (+23±12% (mean±SD); P=0.0038). Previously reported limitations to cut the posterior stroma with FL can therefore not be explained by the difference in collagen organization but by the optical scattering during stromal crossing.

Sbartai A.,CNRS Institute of Analytical Sciences | Sbartai A.,Annaba University | Namour P.,CNRS Institute of Analytical Sciences | Namour P.,IRSTEA | And 12 more authors.
Technical Proceedings of the 2013 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2013 | Year: 2013

The electrodes used in our analyzes are electrodes based on microcrystalline boron-doped diamond (BDD), micromachined by femtosecond laser. The electrochemical performance of the new BDD microelectrodes were first evaluated by the method of differential pulse anodic stripping voltammetric (DPASV) for the simultaneous determination at nanomolar level of four heavy metal ions in water: Cd (II), Ni (II), Pb (II), Hg (II) and then by square wave voltammetric method (SWV) for the determination of uranium. With these approaches are obtained low detection limits 0.4, 6.8, 5.5, and 2.3 nM, respectively for Cd (II), Ni (II) Pb (II) and Hg (II) and 0.5 mg L"' for uranium, less than that of the other sensors described in the literature.

Sbartai A.,University Claude Bernard Lyon 1 | Sbartai A.,Annaba University | Namour P.,University Claude Bernard Lyon 1 | Namour P.,IRSTEA | And 12 more authors.
Analytical Chemistry | Year: 2012

Planar electrochemical microcells were micromachined in a microcrystalline boron-doped diamond (BDD) thin layer using a femtosecond laser. The electrochemical performances of the new laser-machined BDD microcell were assessed by differential pulse anodic stripping voltammetry (DPASV) determinations, at the nanomolar level, of the four heavy metal ions of the European Water Framework Directive (WFD): Cd(II), Ni(II), Pb(II), Hg(II). The results are compared with those of previously published BDD electrodes. The calculated detection limits are 0.4, 6.8, 5.5, and 2.3 nM, and the linearities go up to 35, 97, 48, and 5 nM for, respectively, Cd(II), Ni(II) Pb(II), and Hg(II). The detection limits meet with the environmental quality standard of the WFD for three of the four metals. It was shown that the four heavy metals could be detected simultaneously in the concentration ratio usually measured in sewage or runoff waters. © 2012 American Chemical Society.

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