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Loumena C.,Center Technologique Optique et Lasers | Kirsch A.,Center Technologique Optique et Lasers | Kling R.,Center Technologique Optique et Lasers
ICALEO 2013 - 32nd International Congress on Applications of Lasers and Electro-Optics | Year: 2013

The application of composites and in particular CFRP (Carbon Fiber Reinforced Polymer) for lightweight construction is a booming market. This material tends to gradually replace metals and alloys in many applications such as automotive, renewable energies, aerospace... Indeed, composite materials combine high mechanical performances, low weight and good corrosion resistance. However this highly technical material requires innovative processes in its manufacture, its machining and its maintenance. Laser processes such as cutting, drilling, surface activation and cleaning can compete with conventional and alternative processes. In this paper, we report on paint and polymer layer removal on CFRP substrate with several laser technologies. In addition we make a comparison with alternative processes such as high pressure waterjet, cryogenic pellet and sodium bicarbonate. In order to determine the specific advantages and drawbacks of different laser technologies, we compare different laser/matter interaction, thermo-mechanical and photochemical processes. For thermo-mechanical processes, we used IR and green fiber laser, Nd:YAG, CO 2 TEA and a hand-held laser tool used for cleaning paint on metal and pollutants on stone. For photochemical processes, we used and UV fiber laser and an Excimer source. With these, we can compare the results between the use of high pulse energy (J) at low repetition rate (<100Hz) and the use of low pulse energy (μJ-mJ) at high repetition rate (>10kHz). Results are evaluated in terms of feasibility and damage characterization of carbon fiber or epoxy resin.


Guillemot F.,French Institute of Health and Medical Research | Souquet A.,French Institute of Health and Medical Research | Catros S.,French Institute of Health and Medical Research | Guillotin B.,French Institute of Health and Medical Research | And 9 more authors.
Acta Biomaterialia | Year: 2010

In parallel with ink-jet printing and bioplotting, biological laser printing (BioLP) using laser-induced forward transfer has emerged as an alternative method in the assembly and micropatterning of biomaterials and cells. This paper presents results of high-throughput laser printing of a biopolymer (sodium alginate), biomaterials (nano-sized hydroxyapatite (HA) synthesized by wet precipitation) and human endothelial cells (EA.hy926), thus demonstrating the interest in this technique for three-dimensional tissue construction. A rapid prototyping workstation equipped with an IR pulsed laser (τ = 30 ns, λ = 1064 nm, f= 1-100 kHz), galvanometric mirrors (scanning speed up to 2000 mm s 1) and micrometric translation stages (x, y, z) was set up. The droplet generation process was controlled by monitoring laser fluence, focalization conditions and writing speed, to take into account its mechanism, which is driven mainly by bubble dynamics. Droplets 70 μm in diameter and containing around five to seven living cells per droplet were obtained, thereby minimizing the dead volume of the hydrogel that surrounds the cells. In addition to cell transfer, the potential of using high-throughput BioLP for creating well-defined nano-sized HA patterns is demonstrated. Finally, bioprinting efficiency criteria (speed, volume, resolution, integrability) for the purpose of tissue engineering are discussed. © 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Lazare S.,University of Bordeaux 1 | Sionkowska A.,Nicolaus Copernicus University | Zaborowicz M.,University of Bordeaux 1 | Zaborowicz M.,Nicolaus Copernicus University | And 5 more authors.
Applied Physics A: Materials Science and Processing | Year: 2012

Laser microprocessing of several biopolymers from renewable resources is studied. Three proteinic materials were either extracted from the extracellular matrix like Silk Fibroin/Sericin and collagen, or coming from a commercial source like gelatin. All can find future applications in biomedical experimentation, in particular for cell scaffolding. Films of hundred of microns thick were made by aqueous solution drying and laser irradiation. Attention is paid to the properties making them processable with two laser sources: the ultraviolet and nanosecond (ns) KrF (248 nm) excimer and the infrared and femtosecond (fs) Yb:KGW laser. The UV radiation is absorbed in a one-photon resonant process to yield ablation and the surface foaming characteristics of a laser-induced pressure wave. To the contrary, resonant absorption of the IR photons of the fs laser is not possible and does not take place. However, the high field of the intense I>10 12 W/cm 2 femtosecond laser pulse ionizes the film by the multiphoton absorption followed by the electron impact mechanism, yielding a dense plasma capable to further absorb the incident radiation of the end of the pulse. The theoretical model of this absorption is described in detail, and used to discuss the presented experimental effects (cutting, ablation and foaming) of the fs laser. The ultraviolet laser was used to perform simultaneous multiple spots experiments in which energetic foaming yields melt ejection and filament spinning. Airborne nanosize filaments "horizontally suspended by both ends" (0.25 μm diameter and 10 μm length) of silk biopolymer were observed upon irradiation with large fluences. © 2011 Springer-Verlag.


Bessou M.,French National Center for Scientific Research | Chassagne B.,Center Technologique Optique et Lasers | Caumes J.-P.,French National Center for Scientific Research | Pradere C.,French National Center for Scientific Research | And 3 more authors.
Applied Optics | Year: 2012

Three-dimensional terahertz computed tomography has been used to investigate dried human bones such as a lumbar vertebra, a coxal bone, and a skull, with a direct comparison with standard radiography. In spite of lower spatial resolution compared with x-ray, terahertz imaging clearly discerns a compact bone from a spongy one, with strong terahertz absorption as shown by additional terahertz time-domain transmission spectroscopy. © 2012 Optical Society of America.


Shao K.,University of Bordeaux 1 | Morisset A.,University of Bordeaux 1 | Morisset A.,Center Technologique Optique et Lasers | Pouget V.,University of Bordeaux 1 | And 4 more authors.
Optics Express | Year: 2011

We have performed three-dimensional characterization of the TPA effective laser spot size in silicon using an integrated knife-edge sensor. The TPA-induced response of a CMOS integrated circuit is analyzed based on these results and compared to simulation; we have found that the charge injection capacity in IC's active layer could be influenced by irradiance energy and focus depth. © 2011 Optical Society of America.


Boullet J.,French Atomic Energy Commission | Dubrasquet R.,Center Technologique Optique et Lasers | Medina C.,French Atomic Energy Commission | Bello-Doua R.,Center Technologique Optique et Lasers | And 2 more authors.
Optics Letters | Year: 2010

We report what we believe to be the first millijoule-class ytterbium-doped fiber laser system operating on the zero-phonon line at 977 nm. An actively Q-switched master fiber oscillator delivers nanosecond pulses (FWHM 12-32 ns) at adjustable multiples of 10 kHz repetition rates that are further amplified in an ultralarge core photonic crystal fiber amplifier. At the highest available pumping level, a maximal average power of 78 W was obtained for 32 ns pulses at a repetition rate of 190 kHz, whereas the millijoule energy level was reached for 12 ns pulses at the lower repetition rate of 10 kHz. © 2010 Optical Society of America.


Maine S.,CNRS Optic of Semiconductor nanoStructures Group | Koechlin C.,CNRS Optic of Semiconductor nanoStructures Group | Koechlin C.,ONERA | Rennesson S.,CNRS Optic of Semiconductor nanoStructures Group | And 8 more authors.
Applied Optics | Year: 2012

We retrieve the complex optical index of single-walled carbon nanotube (CNT) films in the 0.6-800 μm spectral range. Results are obtained from a complete set of optical measurements, reflection and transmission, of free-standing CNT films using time domain spectroscopy in the terahertz (THz) and Fourier transform infrared (IR) spectroscopy in the visible-IR. Based on a Drude-Lorentz model, our results reveal a global metallic behavior of the films in the IR, and confirm their high optical index in the THz range. © 2012 Optical Society of America.


Younus A.,French National Center for Scientific Research | Salort S.,Center Technologique Optique et Lasers | Brecur B.,French National Center for Scientific Research | Desbarats P.,French National Center for Scientific Research | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

The potential of terahertz technology has been clearly demonstrated by its large applications in security and defence (remote detection of object). A flexible alternative monochromatic millimeter wave system coupled with an original infrared temperature sensor has been developed to visualize large size 3D manufactured opaque phantoms with different refractive index contrasts. The results clearly illustrate applied terahertz tomography particularities such as boundary effects, refraction and diffraction losses that must be prevented for efficient inspection and detection. © 2010 SPIE.


Lhermite J.,French Atomic Energy Commission | MacHinet G.,French Atomic Energy Commission | Lecaplain C.,CNRS Complex Interprofessional Research in Aerothermochemistry | Boullet J.,French Atomic Energy Commission | And 5 more authors.
Optics Letters | Year: 2010

We report on a passively mode-locked fiber laser emitting around 976 nm. The self-starting mode locking is achieved in an unidirectional ring cavity by means of nonlinear polarization evolution. Stable single-pulse operation is observed for 480 mW of average output power. This all-normal dispersion laser generates naturally chirped pulses with 1 ps duration. The repetition rate is 40.6 MHz, resulting in 12 nJ pulse energy. External compression using bulk grating shortens the pulse duration down to 286 fs. © 2010 Optical Society of America.


Caumes J.-P.,Center Technologique Optique et Lasers | Younus A.,French National Center for Scientific Research | Salort S.,Center Technologique Optique et Lasers | Chassagne B.,Center Technologique Optique et Lasers | And 4 more authors.
Applied Optics | Year: 2011

A monochromatic millimeter-wave imaging system coupled with an infrared temperature sensor has been used to investigate historic objects preserved at the Museum of Aquitaine (France). In particular, two-dimensional and three-dimensional analyses have been performed in order to reveal the internal structure of nearly 3500-year-old sealed Egyptian jars. © 2011 Optical Society of America.

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