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Dive into the research topics where Bertrand Bertussi is active.

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Featured researches published by Bertrand Bertussi.


Optics Express | 2009

Initiation of laser-induced damage sites in fused silica optical components

Bertrand Bertussi; Philippe Cormont; Stéphanie Palmier; Philippe Legros; Jean-Luc Rullier

Significant improvement in the polishing process of fused silica optical components has increased their lifetimes at 351 nm. Nevertheless, for large laser facilities like the LaserMegaJoule (LMJ), zero defect optical components are not yet available. Therefore, a damage mitigation technique has been developed to prevent the growth of the laser-initiated damage sites. Because of the difficulty to produce mitigated sites with sufficiently large depth, the initial morphology of damage to mitigate is a critical issue. The aim of this work is to determine laser parameters (pulse duration, fluence) which permit us to initiate damage sites in accordance with our mitigation process. Confocal microscopy is used to observe damage sites that have sub-surface cracks and consequently to measure precisely the diameter and the depth of the area to mitigate.


Optics Express | 2003

Localized pulsed laser interaction with sub-micronic gold particles embedded in silica: a method for investigating laser damage initiation

Jean-Yves Natoli; Laurent Gallais; Bertrand Bertussi; Annelise During; Mireille Commandre; Jean-Luc Rullier; Florian Bonneau; Patrick Combis

Laser damage phenomena in fused silica are currently under study because of numerous related high power laser applications. Nanosized defects are believed to be responsible for some laser damage initiation. In order to predict and to quantify this initiation process, engineered submicronic gold defects were embedded in silica. The study of these samples by localized pulsed irradiation of isolated gold particles coupled with Nomarski, atomic force and photothermal microscope observations permits us to discriminate between two distinct stages of material modification: one detectable at the surface and the second in the neighbourhood of the embedded particle. Comparison between the observations and simulations results in good agreement if we assume that inclusion melting initiates the damage.


Optics Express | 2003

Integrated photothermal microscope and laser damage test facility for in-situ investigation of nanodefect induced damage.

Annelise During; Mireille Commandré; Caroline Fossati; Bertrand Bertussi; Jean-Yves Natoli; Jean-Luc Rullier; Herve Bercegol; Philippe Bouchut

An integrated setup allowing high resolution photothermal microscopy and laser damage measurements at the same wavelength has been implemented. The microscope is based on photothermal deflection of a transmitted probe beam : the probe beam (633 nm wavelength) and the CW pump beam (1.06 microm wavelength) are collinear and focused through the same objective. In-situ laser irradiation tests are performed thanks to a pulsed beam (1.06 microm wavelength and 6 nanosecond pulse). We describe this new facility and show that it is well adapted to the detection of sub-micronic absorbing defects, that, once located, can be precisely aimed and irradiated. Photothermal mappings are performed before and after shot, on metallic inclusions in dielectric. Results obtained on gold inclusions of about 600 nm in diameter embedded in silica are presented.


Applied Optics | 2006

High-resolution photothermal microscope: a sensitive tool for the detection of isolated absorbing defects in optical coatings

Bertrand Bertussi; Jean-Yves Natoli; Mireille Commandré

The photothermal deflection technique allows us to highlight the presence of inhomogeneities of absorption in optical components. This nondestructive tool is of great interest to the study of the role of contaminants, inclusions, and impurities in the laser-induced damage process. We show that the detection of nanometer-sized isolated absorbing defects requires the development of an adapted photothermal setup with high detectivity and high spatial resolution. Thus it is essential to improve the resolving power up to its theoretical limit.


Boulder Damage Symposium XXXIX: Annual Symposium on Optical Materials for High Power Lasers | 2007

Preliminary results on mitigation of KDP surface damage using the ball dimpling method

François Guillet; Bertrand Bertussi; L. Lamaignère; Xavier Leborgne; Benoît Minot

As laser conditioning ever increases the performance of KDP optics with respect to laser induced bulk damage so that it can meet high-power laser specifications, it is expected that surface damage may become the next threat that must be dealt with. This paper presents new data on surface damage initiation and growth at 3w. A surface damage mitigation process based on the ball-dimpling method is presented along with the first results on the behavior of this process with respect to laser irradiation.


Laser-Induced Damage in Optical Materials: 2004 | 2005

Highlighting of local inhomogeneity in excimer conditioning of KDP

Hervé Piombini; David Damiani; Gilles Damamme; Jean Yves Natoli; Bertrand Bertussi; Mireille Commandre

In order to increase the laser induced damage threshold of KDP crystal, a well-known solution consists in a laser conditioning process. In our case, the irradiation of the crystal is performed with an excimer laser XeF (λ = 351 nm, 16 ns). The improvements in laser damage thresholds measured at CEA/CESTA laboratory (Lutin, Yag facility 2.5 ns, parallel beam) and at CEA/Ripault laboratory (Excimer facility 16 ns, focused beams) are different. A possible reason to explain this difference is the depth of focus between both facilities. In order to minimize the influence of limited depth of focus, a solution consits in a multi-plane conditioning process. By means of a local study, it is possible to exhibit with a high accuracy the Laser Induced Damage Threshold (LIDT) in different planes along sample irradiation axis (z-axis). The laser damage threshold is measured locally (8 μm) at 355 nm with a Nd:Yag (pulse duration 7 ns) at Fresnel Institute Marseille. Using the local LIDT measurements, the purpose of this paper is to highlight the depth of focus in the excimer conditioning process. We demonstrate that it is possible to exhibit a local increase in the conditioning gain till a maximum value, measured with the excimer laser.


Proceedings of SPIE, the International Society for Optical Engineering | 2008

Laser induced fluorescence as a tool for the study of laser damage precursors in transparent materials

Alessandra Ciapponi; Stéphanie Palmier; Frank Wagner; Jean-Yves Natoli; Hervé Piombini; David Damiani; Bertrand Bertussi

Potassium dihydrogen phosphate (KH2PO4 or short KDP) is one of the major nonlinear optical crystals for frequency conversion and electro-optic switching in high power lasers. In particular, this material has been chosen for the frequency converters of the Laser Mega Joule in France and the National Ignition Facility in the US. These laser work close to the damage threshold of the crystals and large efforts have been provided to improve the laser induced damage threshold for KDP at different wavelength. We present in this paper first results of a new setup dedicated to the correlation of non destructive luminescence spectroscopy and destructive laser damage tests. We concentrate on the differences between conventionally grown KDP and KDP-crystals that have been produced by the rapid growth method that has been developed in the last years especially for the large laser installations LMJ and NIF. Different photoluminescence spectra are obtained from conventionally and rapidly grown KDP for both pump configurations: (i) pulsed pumping by the forth harmonic of a Nd:YAG laser at 266nm, and (ii) continuous pumping using a frequency doubled Argon ion laser at 244nm.


Laser-Induced Damage in Optical Materials: 2002 and 7th International Workshop on Laser Beam and Optics Characterization | 2003

Toward an absolute measurement of LIDT

Jean-Yves Natoli; Laurent Gallais; Bertrand Bertussi; Mireille Commandre; Claude Amra

The improvement of LIDT value of optical components had lead to develop a lot of experimental setups and procedures of test around the world. In this context it is often very difficult to make accurate comparisons of laser damage threshold values between the different apparatus. The differences are due to the procedure of test, the spatial and temporal beam variations, the laser damage criterion and others. A specific laser damage testing apparatus, with an accurate damage initiation detection and allowing a real time acquisition of the different shot parameters, lead to exhibit the influence of each parameter on the damage process. Laser beam profiling is performed in real time and give access to the fluence for one pixel (0.2μm2), therefore an effective fluence or a pixel fluence can be calculated in order to reach an “absolute” threshold value. The metrology developed will be detailed and some results obtained on silica and BK7 at 1064nm and 355nm with different procedures of test will be presented and discussed to illustrate the aim of this study.


Laser Damage Symposium XLI: Annual Symposium on Optical Materials for High Power Lasers | 2009

Laser-induced surface damage density measurements of fused silica optics: a parametric study

L. Lamaignère; Stéphane Reyné; Thierry Donval; Roger Courchinoux; Jean-Christophe Poncetta; Bertrand Bertussi; Herve Bercegol

The rasterscan test procedure implemented in order to determine low laser damage density of large aperture UV fused silica optics was improved in terms of accuracy and repeatability. Tests have been carried on several facilities using several pulse durations and spatial distributions. We describe the equipment, test procedure and data analysis to perform this damage test with small beams (Gaussian beams, about 1mm @ 1/e, and top hat beams). Then, beam overlap and beam shape are the two key parameters which are taken into account in order to determine damage density. After data analysis and treatment, a repeatable metrology has been obtained. Moreover, the consideration of error bars on defects distributions permits to compare data between these installations. This allows us to look for reproducibility, a necessary condition in order to share results and to make reliable predictions of laser damage resistance. For that, a careful attention has been paid to beam analysis.


Boulder Damage Symposium XL Annual Symposium on Optical Materials for High Power Lasers | 2008

Effect of thermal annealing on laser damage resistance of KDP at 3ω

François Guillet; Bertrand Bertussi; David Damiani; L. Lamaignère; Audrey Surmin; Karine Valle; Cédric Maunier

In order to characterize the effect of thermal annealing on laser damage resistance of KDP, several combinations of laser conditioning and thermal annealing were applied to two SHG KDP samples. One sample was tested at 3ω, 16ns and the other one at 3ω, 2.5ns. Results show that whereas thermal annealing improves laser damage for a 16ns pulse, no effect can be measured at a pulse length of 2.5ns. Combining laser conditioning and thermal annealing has a stronger effect on laser damage resistance than laser conditioning alone, even for a 2.5ns pulse length for which thermal annealing was found to have little or no influence. It was also found that for a short pulse length maximum gain was obtained when thermal annealing was applied after laser conditioning.

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Laurent Gallais

École Normale Supérieure

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Claude Amra

Aix-Marseille University

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Jean Yves Natoli

Centre national de la recherche scientifique

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Frank Wagner

Aix-Marseille University

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