TY - CONF A1 - Krüger, Jörg T1 - Cleaning of soiled paper model samples using short and ultrashort laser pulses T2 - Konferenz "New Approaches to Book and Paper Conservation-Restoration" CY - Horn, Austria DA - 2011-05-09 PY - 2011 AN - OPUS4-21839 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Pentzien, Simone A1 - Conradi, Andrea A1 - Krüger, Jörg A1 - Wurster, R. ED - M. Castillejo, ED - P. Moreno, ED - M. Oujja, ED - R. Radvan, ED - J. Ruiz, T1 - Monitoring of the laser cleaning process of artificially soiled paper N2 - Laser cleaning of soiled paper is a challenging task due to the fact that a contamination has to be removed and a fragile organic material has to be preserved. The ejection of particles forms a significant channel for the removal of unwanted surface contaminations and can be exploited for an in-situ monitoring of the cleaning procedure. 532-nm-nanosecond single and multi pulse laser cleaning of artificially soiled Whatman© paper was performed. Particles were registered with a dust monitor. These in-situ experiments were combined with ex-situ investigations of cleaning and substrate damage thresholds by means of light and scanning electron microscopic techniques. The cleaning efficiency measured by a multi-spectral imaging system was compared to the in-situ particle monitoring. Additionally, possible color changes of the paper substrate were evaluated. T2 - LACONA VII International Conference, "Lasers in the Conservation of Artworks" CY - Madrid, Spain DA - 2007-09-17 PY - 2008 SN - 978-0-415-47596-9 SP - 345 EP - 351 PB - Taylor & Francis AN - OPUS4-17974 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Eberstein, Markus A1 - Zoheidi, M. A1 - Vogel, Jens A1 - Mann, Guido A1 - Krüger, Jörg ED - Wolf, Jonas C. ED - Luka Lange, T1 - Influence of fictive temperature on laser-induced damage of silica glass KW - Silica glass KW - Fictive temperature KW - Multimode fiber KW - Nanosecond laser KW - Damage threshold PY - 2008 SN - 978-1-60456-578-2 IS - Chapter 10 SP - 275 EP - 286 PB - Nova Science Publishers, Inc. CY - New York, USA AN - OPUS4-17903 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Breakdown limits of optical multimode fibers for the application of nanosecond laser pulses at 532 nm and 1064 nm wavelength T2 - EMRS 2008 Spring Meeting, Symposium B: Laser and plasma in micro- and nano-scale materials processing an diagnostics CY - Strasbourg, France DA - 2008-05-26 PY - 2008 AN - OPUS4-16900 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Jörg A1 - Pentzien, Simone A1 - Conradi, Andrea T1 - Cleaning of artificially soiled paper with 532-nm nanosecond laser radiation N2 - Cleaning of paper is a challenging task due to the fact that a contamination should be removed and a fragile organic original material has to be preserved. Pulsed laser cleaning of artificially soiled Whatman© filter paper samples serving as models for historical paper was performed. Different cleaning strategies employing 8-ns laser pulses at 532 nm wavelength were applied to clean paper avoiding undesired effects like discoloration (yellowing) and mechanical deterioration of the substrate. Multi shot experiments with low-energy pulses were compared with single pulse investigations utilizing high pulse energies achieving a constant energy load incident on the samples in both cases. The cleaning efficiency and possible yellowing effects were evaluated by means of a multi spectral imaging system. An extensive microscopic analysis of the cleaned parts of the samples provided insight into the remaining soiling on the surface and in the bulk of the paper material after laser treatment. As a reference, a hard and a soft eraser were used to clean the samples. KW - Laser cleaning KW - Paper KW - Colorimetry PY - 2008 DO - https://doi.org/10.1007/s00339-008-4476-4 SN - 0947-8396 VL - 92 IS - 1 SP - 179 EP - 183 PB - Springer CY - Berlin AN - OPUS4-17331 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eberstein, Markus A1 - Mann, Guido A1 - Vogel, Jens A1 - Zoheidi, M. A1 - Krüger, Jörg T1 - Influence of Technological Parameters on Nanosecond Laser-induced Surface Damage of Optical Multimode Fibers N2 - High-power optical multimode fibers are essential components for materials processing and surgery and can limit the reliability of expensive systems due to breakdown at the end faces. The breakdown threshold of fibers is determined by intrinsic materials properties and parameters of the technology applied. The aim of this paper is the identification of technological parameters that are crucial for the fiber quality. Fibers were drawn from preforms of Heraeus SWU with core material F300 and a low amount of OH-. Both, the cladding (fluorine doped SiO2) to core diameter ratio (CCDR) and the drawing speed were varied. CCDR values between 1.05 and 1.4 were used. Afterwards, the laser-induced damage thresholds (LIDT) of the fibers were determined. For comparison, also samples from preforms, which underwent different thermal treatments above the transition temperature, were tested with respect to their damage resistivity. Single and multi pulse LIDT measurements were done in accordance with the relevant ISO standards. Nd:YAG laser pulses with durations of 15 ns (1064 nm wavelength) and 8.5 ns (532 nm) at a repetition rate of 10 Hz were utilized. For the fibers, LIDT values (1-on-1, 1064 nm and 532 nm) increased with growing CCDR and with decreasing drawing velocities. KW - Silica glass KW - Multimode fiber KW - Nanosecond laser KW - Damage threshold PY - 2005 SN - 1022-6680 SN - 1662-8985 VL - 39-40 SP - 225 EP - 230 PB - Trans Tech Publ. CY - Zurich AN - OPUS4-17339 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Damage of optical materials as a limit for the application of ultrashort laser pulses T2 - International Conference Advanced Laser Technology (ALT´08) CY - Siófok, Hungary DA - 2008-09-13 PY - 2008 AN - OPUS4-17532 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mann, Guido A1 - Vogel, Jens A1 - Zoheidi, M. A1 - Eberstein, Markus A1 - Krüger, Jörg T1 - Breakdown limits of optical multimode fibers for the application of nanosecond laser pulses at 532 nm and 1064 nm wavelength N2 - For many applications, optical multimode fibers are used for the transmission of powerful laser radiation. High light throughput and damage resistance are desirable. Laser-induced breakdown at the end faces of fibers can limit their performance. Therefore, the determination of laser-induced damage thresholds (LIDT) at the surface of fibers is essential. Nanosecond (1064 nm and 532 nm wavelength) single-shot LIDT were measured according to the relevant standard on SiO2 glass preforms (Suprasil F300) as basic materials of the corresponding fibers. For 10 kinds of fused silica fibers (FiberTech) with core diameters between 180 µm and 600 µm, an illumination approach utilizing a stepwise increase of the laser fluence on a single spot was used. For both wavelengths, the LIDT values (0% damage probability) obtained by means of the two methods were compared. The influence of surface preparation (polishing) on damage resistance was investigated. For equal surface finishing, a correlation between drawing speed of the fibers and their surface LIDT values was found. In addition to the surface measurements, bulk LIDT were determined for the preform material. KW - Fiber waveguides KW - Physical radiation damage KW - Laser-beam impact phenomena KW - Glasses KW - Radiation treatment PY - 2009 DO - https://doi.org/10.1016/j.apsusc.2008.07.157 SN - 0169-4332 SN - 1873-5584 VL - 255 IS - 10 SP - 5519 EP - 5522 PB - North-Holland CY - Amsterdam AN - OPUS4-19036 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Modifikation und Zerstörung von optischen Komponenten als Limit für die Anwendung ultrakurzer Laserimpulse T2 - Institutskolloquium Leibniz-Institut für Oberflächenmodifizierung CY - Leipzig, Germany DA - 2009-05-07 PY - 2009 AN - OPUS4-19112 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Influence of film thickness and optical constants on femtosecond laser-induced damage of hydrongenated amorphous carbon films T2 - European Materials Research Society (EMRS), Spring Meeting 2009 CY - Strasbourg, France DA - 2009-06-08 PY - 2009 AN - OPUS4-19140 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Symietz, Christian A1 - Lehmann, Erhard A1 - Gildenhaar, Renate A1 - Krüger, Jörg A1 - Berger, Georg T1 - Fixierung resorbierbarer Knochenersatzkeramik auf Ti6Al4V-Implantatmaterial mittels Femtosekundenlaser T2 - 5. Thüringer Grenz- und Oberflächentage und 7. Thüringer Biomaterial-Kolloquium CY - Friedrichroda, Deutschland DA - 2009-09-15 KW - Metallprothese KW - Implantat KW - Knochenersatz KW - Bioaktives Material KW - Lasersintern KW - Femtosekundenlaser PY - 2009 SN - 978-3-00-028446-5 SP - 327 AN - OPUS4-20051 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Krüger, Jörg A1 - Pentzien, Simone A1 - Conradi, Andrea A1 - Lußky, Katharina A1 - Engel, P. ED - Günter Wiedemann, ED - Udo Klotzbach, ED - Ulrich Bauer-Bornemann, T1 - Laserreinigung von künstlich verschmutzten europäischen Papieren des 19. Jahrhunderts N2 - Diese Arbeit beschreibt die Laserreinigung von gebräuchlichen Papieren des 19. Jahrhunderts in Kombination mit zwei Schmutzvarianten. Aufgrund der weiten Verbreitung in Bibliotheken und Kunstsammlungen wurden Hadernpapier und holzhaltiges Papier ausgewählt. Als Referenz diente Whatman-Filterpapier. Zur künstlichen Verschmutzung wurden Zeichenkohle oder Standardschmutz (Standard Test Dust SAE J 726 fine, mit Flammruß im Verhältnis 20:1 gemischt) mit Hilfe von Pinsel und Staubsauger jeweils auf die drei Papierarten aufgetragen und in den Faserverbund eingesaugt. Die Nutzung von Modellproben erweist sich für grundlegende Untersuchungen als vorteilhaft, da das Vorhandensein hinreichend großer Flächen (gleichartiger Objekte) für einen Vergleich mit Ergebnissen klassischer Reinigungstechniken unabdingbar ist. Die preiswerten Proben erlauben darüber hinaus auch die Anwendung zerstörender Analysetechniken. Für die Laserreinigungsexperimente wurde ein Nd:YAG-Laser mit Impulsdauern in der Größenordnung von 10 ns bei 532 nm Wellenlänge und einer Repetitionsrate von 500 Hz verwendet. Die Laser-Bearbeitungsstation erlaubt die flächige Bearbeitung von Objekten, wobei der Laserstrahl bewegt wird. Der Laser wird mittels Computer ferngesteuert und unter Klasse-1-Sicherheitsbedingungen betrieben. Bei der Untersuchung der Modellproben wurde jeweils die Anzahl der Impulse pro Probenstelle sowie die Laser-Energiedichte variiert. Ziel der Arbeiten war die Ermittlung eines Laser-Arbeitsbereiches für die Reinigung der verschiedenen Papierproben. Die Modellobjekte wurden vor und nach der Laserbehandlung mittels lichtmikroskopischer, rasterelektronenmikroskopischer und colorimetrischer Analysemethoden untersucht. T2 - Tagung "Laseranwendung in Restaurierung und Denkmalpflege" CY - Osnabrück, Deutschland DA - 2009-01-30 KW - Laserreinigung KW - Nd:YAG-Laser KW - Hadernpapier KW - Holzhaltiges Papier KW - Filterpapier KW - Mikroskopie KW - Farbmessung PY - 2009 SN - 978-3-8167-8106-6 SP - 177 EP - 189 PB - Fraunhofer IRB Verl. CY - Stuttgart AN - OPUS4-20059 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Holle, H. A1 - Kautek, W. A1 - Pentzien, Simone A1 - Krüger, Jörg A1 - Mäder, M. A1 - Schreiner, M. T1 - Laser cleaning on historic picture postcards N2 - This contribution compares traditional cleaning and laser methods. Partial laser cleaning with a nanosecond pulse laser (wavelength of 532 nm) has proved very promising for future application in paper conservation-restoration. Traditional cleaning methods are not always sufficient or successful in surface cleaning of objects of art. Comparative studies of traditional paper cleaning methods and laser cleaning were made on several historic picture postcards printed with the chromolithography technique. PY - 2009 SN - 978-3-85028-490-5 SP - 189 EP - 206 PB - Berger Horn CY - Wien, Austria AN - OPUS4-20397 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Pentzien, Simone A1 - Conradi, Andrea A1 - Lussky, K. A1 - Engel, P. A1 - Krüger, Jörg ED - Engel, Patricia T1 - Laser cleaning of artificially soiled paper N2 - Laser cleaning for works of art on paper might be a supplemental, noncontact method to overcome some of the limitations of traditional dry cleaning techniques. Three different types of paper (pure-cellulose filter paper, rag paper, and wood-pulp paper) were mechanically soiled with pulverized charcoal in a standardized procedure to make model samples. These samples were characterized microscopically and by means of lightness measurements using a multi-spectral imaging system. A prototype laser workstation with Laser Class I conditions for the operator was used for the cleaning experiments. For 10-ns laser pulses at a wavelength of 532 nm, a set of laser parameters was established for a successful cleaning of the samples avoiding damage to the paper substrate. Single- and multi-pulse illumination conditions were tested. An extensive microscopic analysis after laser treatment of the cleaned parts of the samples provided insight into the remaining soiling on the surface and in the bulk of the paper material. PY - 2009 SN - 978-3-85028-490-5 SP - 171 EP - 188 PB - Berger Horn CY - Wien, Austria AN - OPUS4-20398 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - Probing the heat affected zone by chemical modifications in femtosecond pulse laser ablation of titanium nitride films in air N2 - A new approach is presented to quantify the so-called "heat affected zone" (HAZ) during femtosecond laser pulse processing. Ablation of titanium nitride (TiN) thin films (~3 μm thickness) by multiple femtosecond laser pulses (τ=130 fs, λ=800 nm) in air environment was studied by means of two different surface analytical methods both being sensitive to chemical alterations at the surface. Scanning Auger electron microscopy was applied for a visualization of the spatial distribution of specific elements (Ti, O) within the laser-modified areas. The chemical state of the irradiated surface was revealed by complementary x-ray photoelectron spectroscopy. Both methods were used for a depth-profiling chemical analysis (tracking the elements Ti, N, O, and C) using an Ar-ion beam for surface sputtering. In a narrow laser fluence range slightly below the ablation threshold of TiN significant superficial oxidation can be observed leading to the formation of substoichiometric TiO2-x. At fluences above the ablation threshold, an increased titanium concentration is observed within the entire ablation craters. Following upon sputter removal the elemental distribution into the depth of the nonablated material, the results allow an estimation of the heat-affected zone for femtosecond laser ablation in air environment. According to our analyses, the HAZ extends up to a few hundreds of nanometers into the nonablated material. KW - Femtosecond laser ablation KW - Heat affected zone KW - Titanium nitride KW - Scanning Auger electron microscopy KW - X-ray KW - Photoelektron spectroscopy PY - 2010 UR - http://link.aip.org/link/?JAP/107/054902 DO - https://doi.org/10.1063/1.3311552 SN - 0021-8979 SN - 1089-7550 VL - 107 IS - 5 SP - 054902-1 - 054902-5 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-20949 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mann, Guido A1 - Jurke, Mathias A1 - Zoheidi, M. A1 - Eberstein, Markus A1 - Krüger, Jörg T1 - Influence of core diameter and coating material on nanosecond laser-induced damage threshold of optical multimode fibers N2 - Single and multi pulse laser-induced damage thresholds (LIDT) of core, cladding, and coating materials of high-power optical multimode fibers were determined in accordance with ISO 11254 for 532 nm and 1064 nm wavelength in the 10-ns pulse duration regime with spatial Gaussian beam shape. For all-silica fibers, LIDT increases with rising core diameter in a range between 100-600 µm for a constant cladding-core ratio of 1.2. The damage resistance of the low refracting cladding (0.3 % fluorine doped fused silica) is comparable to the undoped SiO2 core. Coating materials show significantly lower LIDT than light-guiding parts of the fibers. KW - Fiber waveguides (42.81.Qb) KW - Physical radiation damage (61.80.-x) KW - Laser-beam impact phenomena (79.20.Ds) KW - Glasses (81.05.Kf) PY - 2010 SN - 1454-4164 VL - 12 IS - 3 SP - 711 EP - 714 PB - INOE & INFM CY - Bucharest AN - OPUS4-21083 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Koter, Robert A1 - Weise, Matthias A1 - Hertwig, Andreas A1 - Beck, Uwe A1 - Krüger, Jörg T1 - Influence of film thickness and optical constants on femtosecond laser-induced ablation of hydrogenated amorphous carbon films N2 - Hydrogenated amorphous carbon layers were deposited on BK7 glass in a plasma-assisted chemical vapor deposition process. Low and high refracting films with thicknesses d ranging from 11 nm to 5.8 µm were produced having refractive indices n between 1.68 and 2.41 and linear absorption coefficients of α~100 cm-1 and α~20000 cm-1 at 800 nm wavelength as a result of different plasma modes. Laser ablation thresholds Fth in dependence on d were determined using 30-fs laser pulses. Low absorbing layers show a constant Fth while Fth increases with rising d up to the optical penetration depth of light α-1 for high absorbing films. KW - Physical radiation damage (61.80.-x) KW - Laser-beam impact phenomena (79.20.Ds) KW - Radiation treatment (81.40.Wx) KW - Carbon (81.05.Uw) KW - Optical constants (78.20.Ci) PY - 2010 SN - 1454-4164 VL - 12 IS - 3 SP - 663 EP - 667 PB - INOE & INFM CY - Bucharest AN - OPUS4-21084 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Mikrobearbeitung mit ultrakurzen Laserimpulsen T2 - Seminar Laser-Materialbearbeitung für die industrielle Fertigung (Photon Laser Engineering) CY - Berlin, Germany DA - 2010-03-23 PY - 2010 AN - OPUS4-22574 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn A1 - Rosenfeld, A. A1 - Krüger, Jörg ED - Panchenko, V. ED - Mourou, G. ED - Zheltikov, A. M. T1 - Femtosecond laser-induced periodic surface structures: recent approaches to explain their sub-wavelength periodicities N2 - The formation of laser-induced periodic surface structures (LIPSS) upon irradiation of semiconductors and dielectrics by linearly polarized high-intensity Ti:sapphire fs-laser pulses (τ ~100 fs, λ ~800 nm) is studied experimentally and theoretically. In the experiments, two different types of LIPSS exhibiting very different spatial periods are observed (socalled LSFL – low spatial frequency LIPSS, and HSFL - high spatial frequency LIPSS), both having a different dependence on the incident laser fluence and pulse number per spot. The experimental results are analyzed by means of a new theoretical approach, which combines the generally accepted LIPSS theory of J. E. Sipe and co-workers [Phys. Rev. B 27, 1141-1154 (1983)] with a Drude model, in order to account for transient changes of the optical properties of the irradiated materials. The joint Sipe-Drude model is capable of explaining numerous aspects of fs-LIPSS formation, i.e., the orientation of the LIPSS, their fluence dependence as well as their spatial periods. The latter aspect is specifically demonstrated for silicon crystals, which show experimental LSFL periods Λ somewhat smaller than λ. This behaviour is caused by the excitation of surface plasmon polaritons, SPP, (once the initially semiconducting material turns to a metallic state upon formation of a dense free-electron-plasma in the material) and the subsequent interference between its electrical fields with that of the incident laser beam, resulting in a spatially modulated energy deposition at the surface. Upon multi-pulse irradiation, a feedback mechanism, caused by the redshift of the resonance in a grating-assisted SPP excitation, is further reducing the LSFL spatial periods. The SPP-based mechanism of LSFL successfully explains the remarkably large range of LSFL periods between ~0.6 λ and λ. T2 - LAT 2010 - International Conference on Lasers, Applications, and Technologies CY - Kazan, Russia DA - 23.08.2010 KW - Femtosecond laser ablation KW - Laser-induced periodic surface structures (LIPSS) KW - Surface plasmon polaritons KW - Second harmonic generation (SHG) KW - Silicon KW - Semiconductors KW - Dielectrics PY - 2011 DO - https://doi.org/10.1117/12.879813 SN - 0277-786X N1 - Serientitel: Proceedings of SPIE – Series title: Proceedings of SPIE VL - 7994 SP - 79940M-1 EP - 79940M-10 CY - Bellingham, USA AN - OPUS4-23291 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Friedrich, Jörg Florian A1 - Krüger, P. ED - Blasek, G. ED - Bräuer, G. T1 - Feinreinigung von Oberflächen mit Niederdruckplasmen KW - Plasma-Oberflächenreinigung PY - 2010 SN - 978-3-87480-257-4 IS - Kap. 3.15 SP - 1085 EP - 1106 PB - Eugen G. Leuze CY - Bad Saulgau AN - OPUS4-23273 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pentzien, Simone A1 - Conradi, Andrea A1 - Koter, Robert A1 - Krüger, Jörg ED - Engel, P. ED - Schirò, J. ED - Larsen, R. ED - Moussakova, E. ED - Kecskeméti, I. T1 - Cleaning of soiled paper model samples using short and ultrashort laser pulses N2 - Paper is one of the most important materials representing and witnessing human culture particularly as a carrier medium for text and image. As soiling hampers the reception of information, paper cleaning techniques are needed. Traditional mechanical and chemical cleaning methods are used by conservator-restorers. In some cases, a classical cleaning procedure of paper objects yields unsatisfactory results or a conventional treatment is even impossible. Especially, fragile paper objects cause problems due to mechanical instabilities. Laser cleaning as a non-contact method might be a way to overcome some of the limitations of classical cleaning techniques. Laser parameters have to be chosen to achieve removal of the soiling without influencing the artwork. Any immediate as well as long-term effects causing an irreversible change of the artwork have to be avoided. At present, most laser applications are found in stone and metal conservation, while laser treatment of complex organic materials like paper is still not fully developed for application in conservators' workshops. This contribution describes recent work of pulsed laser cleaning of soiled model samples. Pure cellulose, rag paper and wood-pulp paper were mechanically soiled with pulverized charcoal in a standardized procedure to make model samples representing essential characteristics of contaminated real-world artworks. Afterwards, model samples were cleaned using short and ultrashort laser pulses in the nanosecond and femtosecond time domain, respectively. An extensive analysis of the model samples after laser treatment using an optical microscope and a multi-spectral imaging system allows a comparison of the cleaning results obtained with both laser sources. T2 - Conference 'New Approaches to Book and Paper Conservation - Restoration' CY - Horn, Austria DA - 09.05.2011 KW - Laser cleaning KW - Ablation KW - Laser impact on surfaces KW - Paper KW - Femtosecond laser KW - Nanosecond laser PY - 2011 SN - 978-3-85028-518-6 SP - 519 EP - 532 PB - Verlag Berger, Horn CY - Vienna, Austria AN - OPUS4-23705 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Rosenfeld, A. A1 - Krüger, Jörg T1 - Implications of transient changes of optical and surface properties of solids during femtosecond laser pulse irradiation to the formation of laser-induced periodic surface structures N2 - The formation of laser-induced periodic surface structures (LIPSS) upon irradiation of silicon wafer surfaces by linearly polarized Ti:sapphire femtosecond laser pulses (pulse duration 130 fs, central wavelength 800 nm) is studied experimentally and theoretically. In the experiments, so-called low-spatial frequency LIPSS (LSFL) were found with periods smaller than the laser wavelength and an orientation perpendicular to the polarization. The experimental results are analyzed by means of a new theoretical approach, which combines the widely accepted LIPSS theory of Sipe et al. with a Drude model, in order to account for transient (intra-pulse) changes of the optical properties of the irradiated materials. It is found that the LSFL formation is caused by the excitation of surface plasmon polaritons, SPPs, once the initially semiconducting material turns to a metallic state upon formation of a dense free-electron-plasma in the material and the subsequent interference between its electrical field with that of the incident laser beam resulting in a spatially modulated energy deposition at the surface. Moreover, the influence of the laser-excited carrier density and the role of the feedback upon the multi-pulse irradiation and its relation to the excitation of SPP in a grating-like surface structure is discussed. KW - Femtosecond laser ablation KW - Laser-induced periodic surface structures KW - (LIPSS) KW - Optical properties KW - Surface plasmon polaritons KW - Semiconductors KW - Silicon PY - 2011 DO - https://doi.org/10.1016/j.apsusc.2010.11.059 SN - 0169-4332 SN - 1873-5584 VL - 257 IS - 12 SP - 5420 EP - 5423 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-23309 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Symietz, Christian A1 - Lehmann, Erhard A1 - Gildenhaar, Renate A1 - Koter, Robert A1 - Berger, Georg A1 - Krüger, Jörg T1 - Fixation of bioactive calcium alkali phosphate on Ti6Al4V implant material with femtosecond laser pulses N2 - Bone implants made of metal, often titanium or the titanium alloy Ti6Al4V, need to be surface treated to become bioactive. This enables the formation of a firm and durable connection of the prosthesis with the living bone. We present a new method to uniformly cover Ti6Al4V with a thin layer of ceramics that imitates bone material. These calcium alkali phosphates, called GB14 and Ca10, are applied to the metal by dip coating of metal plates into an aqueous slurry containing the fine ceramic powder. The dried samples are illuminated with the 790 nm radiation of a pulsed femtosecond laser. If the laser fluence is set to a value just below the ablation threshold of the ceramic (ca. 0.4 J/cm²) the 30 fs laser pulses penetrate the partly transparent ceramic layer of 20–40 µm thickness. The remaining laser fluence at the ceramic–metal interface is still high enough to generate a thin metal melt layer leading to the ceramic fixation on the metal. The laser processing step is only possible because Ti6Al4V has a lower ablation threshold (between 0.1 and 0.15 J/cm²) than the ceramic material. After laser treatment in a fluence range between 0.1 and 0.4 J/cm², only the particles in contact with the metal withstand a post-laser treatment (ultrasonic cleaning). The non-irradiated rest of the layer is washed off. In this work, we present results of a successful ceramic fixation extending over larger areas. This is fundamental for future applications of arbitrarily shaped implants. KW - Bone implant KW - Bioceramic coating KW - Titanium KW - Calcium phosphate KW - Femtosecond laser PY - 2011 DO - https://doi.org/10.1016/j.apsusc.2010.10.046 SN - 0169-4332 SN - 1873-5584 VL - 257 IS - 12 SP - 5208 EP - 5212 PB - North-Holland CY - Amsterdam AN - OPUS4-23310 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pentzien, Simone A1 - Conradi, Andrea A1 - Krüger, Jörg T1 - The influence of paper type and state of degradation on laser cleaning of artificially soiled paper N2 - Lasers can be a supplemental tool for restorers to overcome some of the limitations of traditional dry cleaning techniques for works of art on paper. The laser working range has to be optimized allowing for safe removal of contamination and limitation of damage to the substrate. This paper addresses the influence of paper type and state of degradation on laser working range. Three types of new paper (pure cellulose, bleached pulp paper, rag paper) were degraded and characterized with respect their degree of polymerization. Laser-induced damage thresholds of new and degraded paper were determined using SEM and viscometry. Additionally, artificially soiled model samples were made using two kinds of soiling, namely pulverized charcoal and soot-blackened standard test dust. Cleaning thresholds of soiled paper samples were evaluated. A working range for all combinations of paper and soiling between 0.05 J/cm2 and 0.5 J/cm2 was found for the application of 8-ns laser pulses at 532 nm wavelength. T2 - LACONA VIII - Lasers in the Conservation of Artworks VIII CY - Sibiu, Romania DA - 21.09.2009 KW - Nanosecond laser cleaning KW - Paper KW - Ageing KW - Degree of polymerization KW - Cleaning threshold KW - Damage threshold PY - 2011 SN - 978-0-415-58073-1 SP - 59 EP - 65 PB - Taylor & Francis CY - London, UK AN - OPUS4-23634 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Laserreinigung von künstlich verschmutzten europäischen Papieren des 19. Jahrhunderts T2 - Tagung Laseranwendung in Restaurierung und Denkmalpflege CY - Osnabrück, Germany DA - 2009-01-29 PY - 2009 AN - OPUS4-18228 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - The influence of paper type and state of degradation on laser cleaning of artifically soiled paper T2 - Konferenz LACONA 8 CY - Sibiu, Romania DA - 2009-09-21 PY - 2009 AN - OPUS4-19288 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Rosenfeld, A. A1 - Krüger, Jörg T1 - On the role of surface plasmon polaritons in the formation of laser-induced periodic surface structures upon irradiation of silicon by femtosecond-laser pulses N2 - The formation of nearly wavelength-sized laser-induced periodic surface structures (LIPSSs) on single-crystalline silicon upon irradiation with single or multiple femtosecond-laser pulses (pulse duration τ=130 fs and central wavelength λ=800 nm) in air is studied experimentally and theoretically. In our theoretical approach, we model the LIPSS formation by combining the generally accepted first-principles theory of Sipe and co-workers with a Drude model in order to account for transient intrapulse changes in the optical properties of the material due to the excitation of a dense electron-hole plasma. Our results are capable to explain quantitatively the spatial periods of the LIPSSs being somewhat smaller than the laser wavelength, their orientation perpendicular to the laser beam polarization, and their characteristic fluence dependence. Moreover, evidence is presented that surface plasmon polaritons play a dominant role during the initial stage of near-wavelength-sized periodic surface structures in femtosecond-laser irradiated silicon, and it is demonstrated that these LIPSSs can be formed in silicon upon irradiation by single femtosecond-laser pulses. KW - Ab initio calculations KW - Elemental semiconductors KW - High-speed optical techniques KW - Laser beam effects KW - Polaritons KW - Silicon KW - Solid-state plasma KW - Surface plasmons KW - Surface structure PY - 2009 DO - https://doi.org/10.1063/1.3261734 SN - 0021-8979 SN - 1089-7550 VL - 106 IS - 10 SP - 104910-1 - 104910-5 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-20453 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - The production of metallic implant materials with a bioactive ceramic layer using femtosecond laser pluses T2 - ISL 2010 - 3rd International Symposium on Laser-Micromachining CY - Chemnitz, Germany DA - 2010-10-27 PY - 2010 AN - OPUS4-21901 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pentzien, Simone A1 - Conradi, Andrea A1 - Koter, Robert A1 - Krüger, Jörg T1 - Cleaning of artificially soiled paper using nanosecond, picosecond and femtosecond laser pulses N2 - Cleaning of cultural assets, especially fragile organic materials like paper, is a part of the conservation process. Laser radiation as a non-contact tool offers prospects for that purpose. For the studies presented here, paper model samples were prepared using three different paper types (pure cellulose, rag paper, and wood-pulp paper). Pure cellulose serves as reference material. Rag and woodpulp paper represent essential characteristics of the basic materials of real-world artworks. The papers were mechanically soiled employing pulverized charcoal. Pure and artificially soiled paper samples were treated with laser pulses of 28 fs (800 nm wavelength) and 8–12 ns (532 nm) duration in a multi pulse approach. Additionally, the cellulose reference material was processed with 30 ps (532 nm) laser pulses. Damage and cleaning thresholds of pure and soiled paper were determined for the different laser regimes. Laser working ranges allowing for removal of contamination and avoiding permanent modification to the substrate were found. The specimens prior and after laser illumination were characterized by light-optical microscopy (OM) and scanning electron microscopy (SEM) as well as multi spectral imaging analysis. The work extends previous nanosecond laser cleaning investigations on paper into the ultra-short pulse duration domain. KW - Laser cleaning KW - Ablation KW - Laser impact on surfaces KW - Paper KW - Femtosecond laser PY - 2010 DO - https://doi.org/10.1007/s00339-010-5809-7 SN - 0947-8396 VL - 101 IS - 2 SP - 441 EP - 446 PB - Springer CY - Berlin AN - OPUS4-22155 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn A1 - Solis, J. A1 - Spielmann, C. A1 - Lippert, T. A1 - Krüger, Jörg T1 - Damage mechanisms in polymers upon NIR femtosecond pulse laser irradiation: sub-threshold processes and their implications for laser safety applications N2 - This contribution investigates laser-induced damage of thin film and bulk polymer samples, with the focus on physical processes occurring close to the damage threshold. In-situ real-time reflectivity (RTR) measurements with picosecond (ps) and nanosecond (ns) temporal resolution were performed on thin polymer films on a timescale up to a few microseconds (µs). A model for polymer thin film damage is presented, indicating that irreversible chemical modification processes take place already below the fluence threshold for macroscopic damage. On dye-doped bulk polymer filters (as used for laser goggles), transmission studies using fs-and ps-laser pulses reveal the optical saturation behavior of the material and its relation to the threshold of permanent damage. Implications of the sub-threshold processes for laser safety applications will be discussed for thin film and bulk polymer damage. T2 - International high-power laser ablation conference CY - Santa Fe, USA DA - 2010-04-18 KW - Polymer KW - Laser damage KW - Ultrashort laser pulses KW - Time-resolved reflectivity measurements KW - Laser safety PY - 2010 UR - http://link.aip.org/link/?APCPCS/1278/56/1 SN - 978-0-7354-0828-9 DO - https://doi.org/10.1063/1.3507148 N1 - Serientitel: AIP conference proceedings – Series title: AIP conference proceedings IS - 1278 SP - 56 EP - 64 PB - American Institute of Physics CY - Melville, NY, USA AN - OPUS4-22156 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Krüger, Jörg A1 - Kautek, Wolfgang T1 - Ultrashort Pulse Laser Interaction with Dielectrics and Polymers N2 - Abstract Femtosecond laser micromachining has excited vivid attention in various industri- al fields and in medicine owing to the advantages of ultrashort laser pulses compared to long-pulse treatment.These are mainly the reduction of the laser fluence needed to induce ablation and the improvement of the contour sharpness of the laser-generated structures. Recently,special attention was paid to femtosecond laser experiments on nonabsorbing in- organic dielectrics.This is due to the fact that optical damage in dielectric optical elements limits the performance of high-power laser systems.Despite the fact that a large variety of organic polymers can be machined with excimer lasers successfully,the involvement of thermal processes can lead to an unsatisfactory quality of the structures.Ultrashort,fs-laser pulses might be an alternative for the treatment of polymers.Therefore,femtosecond laser machining investigations of dielectrics and polymers are reviewed in this paper.Similarities and differences of the ablation behavior of both material classes are discussed.The influ- ence of the bandgap on the ablation threshold in dependence on the pulse duration,the en- hancement of the machining precision with a shortening of the pulse duration,incubation phenomena,and morphological features appearing on the surface after femtosecond laser treatment are mentioned.Possible applications,e.g.,in medicine and biosensors,are de- scribed. KW - Dielectrics KW - Femtosecond laser KW - Micromachining KW - Ablation KW - Polymers PY - 2004 SN - 3-540-40471-6 N1 - Serientitel: Advances in polymer science – Series title: Advances in polymer science IS - 168 SP - 247 EP - 289 PB - Springer CY - Berlin AN - OPUS4-3262 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Femtosecond Laser Micromachining: Potentials, Applications, Safety Aspects T2 - Materials Seminar Series, Paul Scherrer Institut CY - Villigen, Switzerland DA - 2003-05-19 PY - 2003 AN - OPUS4-4360 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Hertwig, Andreas A1 - Martin, Sven A1 - Krüger, Jörg A1 - Spielmann, C. A1 - Lenner, M. A1 - Kautek, Wolfgang ED - Dausinger, F. ED - Lichtner, F. ED - Lubatschowski, H. T1 - Primary hazards and reliability of protective materials N2 - Femtosecond laser pulses are close to industrial use. The advantages of ultrashort laser pulses for micromachining applications especially in the case of dielectric and biological samples down to pulse durations of 5 fs have been established. The current international standards of laser safety are primarily concerned with CW and pulsed lasers down to the nanosecond range. Therefore, human tissue and laser-protection equipment was investigated with respect to its resistance and protection performance for femtosecond laser illumination down to 30 fs. This included filter glasses for laser protection eyewear, polymer and textile materials used in curtains and guards. Bulk absorber filters can provide enough protection against laser radiation, give a sufficiently broad absorption spectrum. Materials are damaged more easily by femtosecond laser radiation. The need for sufficient spectral broadness as well as the different damage thresholds have to be included in international laser safety standards. This work should trigger the development of novel eye-protection devices that are lighter and ergonomically more acceptable than present commercial models. KW - Lasersicherheit KW - Kurzpulslaser KW - Femtosekunden KW - Lasertechnik KW - Materialbearbeitung PY - 2004 SN - 3-540-20114-9 DO - https://doi.org/10.1007/b96440 SN - 0303-4216 N1 - Serientitel: Topics in applied physics – Series title: Topics in applied physics IS - 96 SP - 287 EP - 307 PB - Springer CY - Berlin AN - OPUS4-4661 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kautek, Wolfgang A1 - Pentzien, Simone A1 - Röllig, Mathias A1 - Rudolph, Pascale A1 - Krüger, Jörg A1 - Maywald-Pitellos, C. A1 - Bansa, H. A1 - Grösswang, H. A1 - König, E. T1 - Near-UV laser interaction with contaminants and pigments on parchment: laser cleaning diagnostics by SE-microscopy, VIS-, and IR-spectroscopy PY - 2000 SN - 1296-2074 SN - 1778-3674 VL - 1 IS - sup.1 PB - Elsevier CY - Paris AN - OPUS4-5981 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Paatsch, Wolfgang A1 - Kautek, Wolfgang A1 - Krüger, Jörg T1 - Structuring and Plating of Materials with Ultrashort Laser Pulses PY - 2000 SN - 0016-4232 VL - 91 IS - 5 SP - 1271 EP - 1275 PB - Leuze CY - Saulgau, Württ. AN - OPUS4-6000 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Baudach, Steffen A1 - Krüger, Jörg A1 - Kautek, Wolfgang T1 - Femtosecond Laser Processing of Soft Materials KW - Femtosecond pulse laser KW - Laser processing KW - Polymer ablation KW - Nanostructures PY - 2001 SN - 0387-0200 VL - 29 IS - 11 SP - 705 EP - 709 PB - Gakkai CY - Suita AN - OPUS4-6006 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Bonse, Jörn A1 - Baudach, Steffen A1 - Krüger, Jörg A1 - Kautek, Wolfgang ED - Exarhos, G. T1 - Femtosecond laser damage in dielectric coatings N2 - Multi-shot investigations of Ti:sapphire laser (wavelength (lambda) approximately equals 800 nm) induced damage were performed in three different laboratories (BAM, Berlin; LZH, Hannover; UNM, Albuquerque). The ablation behavior of a high reflecting mirror consisting of alternating (lambda) /4- layers of Ta2O5 and SiO2 was studied. Fused silica served as substrate. The influence of the pulse duration ((tau) equals 13 - 130 fs), the pulse number (30 - (infinity) ) and the repetition rate (10 Hz - 100 MHz) on the damage threshold will be discussed. T2 - 32nd Annual Boulder Damage Symposium CY - Boulder, CO, USA DA - 2000-10-16 PY - 2001 SN - 0-8194-4036-1 DO - https://doi.org/10.1117/12.425056 SN - 1605-7422 N1 - Serientitel: SPIE proceedings series – Series title: SPIE proceedings series IS - 4347 SP - 24 EP - 34 PB - International Society for Optical Engineering (SPIE) CY - Bellingham, Wash. AN - OPUS4-6013 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Kautek, Wolfgang A1 - Pentzien, Simone A1 - Rudolph, Pascale A1 - Krüger, Jörg A1 - Maywald-Pitellos, C. A1 - Bansa, H. A1 - Grösswang, H. A1 - König, W. ED - Fotakis, C. T1 - Near-Ultraviolet Pulsed Laser Interaction with Contaminants and Pigments on Parchment: Spectroscopic Diagnostics for Laser Cleaning Safety T2 - 5th International Conference on Optics within Life Sciences CY - H¯erakleion, Greece DA - 1998-01-01 PY - 2000 SN - 3-540-66648-6 N1 - Serientitel: Optics within life sciences – Series title: Optics within life sciences IS - 5 SP - 100 EP - 107 PB - Springer CY - Berlin AN - OPUS4-6189 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Martin, Sven A1 - Hertwig, Andreas A1 - Lenzner, Matthias A1 - Krüger, Jörg A1 - Kautek, Wolfgang T1 - Spot-size dependence of the ablation threshold in dielectrics for femtosecond laser pulses N2 - The multi-pulse ablation threshold of barium borosilicate glass was measured using 30-fs pulses of a high repetition rate (1 kHz) laser system. The threshold fluence was found to decrease with increasing beam radius ranging from 20 to 400 m. Two existing models are applied by considering thermal accumulation and point defects, respectively . PY - 2003 DO - https://doi.org/10.1007/s00339-003-2213-6 SN - 0947-8396 VL - 77 IS - 7 SP - 883 EP - 884 PB - Springer CY - Berlin AN - OPUS4-6317 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Jörg A1 - Meja, P. A1 - Autric, M. A1 - Kautek, Wolfgang T1 - Femtosecond pulse laser ablation of anodic oxide coatings on aluminium alloys with on-line acoustic observation N2 - The 125-fs laser ablation behaviour (800 nm) of aluminium and anodic oxide coatings on an AlMgSi1 alloy was investigated. The multi-pulse ablation threshold of aluminium at 1.2 J cm-2 was less than that of the oxides of 2–3 J cm-2. Aluminium exhibited a single pulse modification (melting) threshold of 0.3 J cm-2. These values derived from an evaluation of the crater geometry coincided with on-line acoustic measurements. The detected microphone voltage amplitude increased linearly with the laser fluence. The morphology of the ablation craters on aluminium indicated melt formation and displacement of a homogeneous melt phase due to the recoil action of the expanding metal vapour. The laser-processed ceramic oxide phases, on the other hand, showed a spongy resolidified melt layer, which denotes a collocated in-depth formation both of a melt and a gas phase. These phenomena are discussed in terms of the relative dominance of penetration depth of laser light and heat affected zones in the investigated materials with strongly varying optical and thermodynamical properties. KW - Laser ablation KW - Acoustic measurement KW - Microphone KW - Aluminium KW - Aluminium oxide PY - 2002 SN - 0169-4332 SN - 1873-5584 VL - 186 IS - 1-4 SP - 374 EP - 380 PB - North-Holland CY - Amsterdam AN - OPUS4-6324 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Baudach, Steffen A1 - Krüger, Jörg A1 - Kautek, Wolfgang A1 - Lenzner, Matthias T1 - Femtosecond laser ablation of silicon-modification thresholds and morphology N2 - We investigated the initial modification and ablation of crystalline silicon with single and multiple Ti:sapphire laser pulses of 5 to 400 fs duration. In accordance with earlier established models, we found the phenomena amorphization, melting, re-crystallization, nucleated vaporization, and ablation to occur with increasing laser fluence down to the shortest pulse durations. We noticed new morphological features (bubbles) as well as familiar ones (ripples, columns). A nearly constant ablation threshold fluence on the order of 0.2 J/cm2 for all pulse durations and multiple-pulse irradiation was observed. For a duration of ,100 fs, significant incubation can be observed, whereas for 5 fs pulses, the ablation threshold does not depend on the pulse number within the experimental error. For micromachining of silicon, a pulse duration of less than 500 fs is not advantageous. PY - 2002 DO - https://doi.org/10.1007/s003390100893 SN - 0947-8396 VL - 74 IS - 1 SP - 19 EP - 25 PB - Springer CY - Berlin AN - OPUS4-6328 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jeschke, H.O. A1 - Garcia, M.E. A1 - Lenzner, Matthias A1 - Bonse, Jörn A1 - Krüger, Jörg A1 - Kautek, Wolfgang T1 - Laser ablation thresholds of silicon for different pulse durations: theory and experiment N2 - The ultrafast laser ablation of silicon has been investigated experimentally and theoretically. The theoretical description is based on molecular dynamics (MD) simulations combined with a microscopic electronic model. We determine the thresholds of melting and ablation for two different pulse durations =20 and 500 fs. Experiments have been performed using 100 Ti:Sap-phire laser pulses per spot in air environment. The ablation thresholds were determined for pulses with a duration of 25 and 400 fs, respectively. Good agreement is obtained between theory and experiment. KW - Laser ablation KW - Pulse duration KW - Threshold of silicon PY - 2002 DO - https://doi.org/10.1016/S0169-4332(02)00458-0 SN - 0169-4332 SN - 1873-5584 VL - 197-198 SP - 839 EP - 844 PB - North-Holland CY - Amsterdam AN - OPUS4-6314 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Jörg Florian A1 - Möller, B. A1 - Kühn, Gerhard A1 - Unger, Wolfgang A1 - Krüger, P. T1 - Improvement of adhesion properties of polymers by producing oxyfluorinated surfaces PY - 2001 SN - 0016-4232 VL - 92 IS - 5 SP - 1334 EP - 1444 PB - Leuze CY - Saulgau, Württ. AN - OPUS4-6973 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, P. A1 - Knes, R. A1 - Friedrich, Jörg Florian T1 - Surface cleaning by plasma-enhanced desorption of contaminants PY - 1999 SN - 0257-8972 VL - 112 SP - 240 EP - 244 PB - Elsevier Science CY - Lausanne AN - OPUS4-6984 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, P. A1 - Friedrich, Jörg Florian A1 - Meyer-Plath, Asmus T1 - Gezielte chemische Funktionalisierung von porösen Materialien und Bauteilen aus der Mikrosystemtechnik T2 - Workshop Funktionalisierung von Oberflächen für die Biotechnologie CY - Dresden, Deutschland DA - 2003-03-11 PY - 2003 SP - 1(?) EP - 8(?) PB - EFDS CY - Dresden AN - OPUS4-6962 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, P. A1 - Friedrich, Jörg Florian A1 - Meyer-Plath, Asmus T1 - Selective chemical modification of porous materials and films for bio-medical applications T2 - CIP 2003 ; 14th International Colloquium on Plasma Processes CY - Antibes, France DA - 2003-06-30 PY - 2003 SP - 1(?) EP - 4(?) PB - sfv, Sociéte Française du Vide CY - Paris AN - OPUS4-6963 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Krüger, P. A1 - Friedrich, Jörg Florian ED - Mennig, G. T1 - Modifizierung von Polymeren im Niederdruckplasma T2 - 15. Fachtagung über Verarbeitung und Anwendung von Polymeren CY - Chemnitz, Deutschland DA - 1997-11-13 PY - 1997 SN - 3-00-001942-1 IS - B27 SP - 1 EP - 8 PB - Techn. Univ. CY - Chemnitz AN - OPUS4-6992 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, P. A1 - Wigant, L. A1 - Friedrich, Jörg Florian ED - Nowack, H. T1 - Permeabilitätsverminderung von Polyolefinfilmen durch Plasmapolymerbeschichtungen T2 - 5. Internationale Fachtagung - ND-Plasma-Technologie CY - Duisburg, Deutschland DA - 1997-09-22 PY - 1997 VL - 5 SP - 1(?) EP - 16(?) PB - Print-Service CY - Mülheim AN - OPUS4-6996 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, P. A1 - Friedrich, Jörg Florian T1 - Gezielte chemische Funktionalisierung von Polymermaterialien T2 - 4. Wörlitzer Workshop "Funktionelle Schichten" CY - Wörlitz, Deutschland DA - 2003-05-27 PY - 2003 VL - 4 SP - 1(?) EP - 7(?) PB - EFDS CY - Dresden AN - OPUS4-7289 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Determination of a working range for the laser cleaning of soiled silk T2 - Konferenz LACONA VI, Lasers in the Conservation of Artworks CY - Vienna, Austria DA - 2005-09-21 PY - 2005 AN - OPUS4-7135 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -