TY - JOUR A1 - Kraft, Sebastian A1 - Schille, J. A1 - Bonse, Jörn A1 - Löschner, U. A1 - Krüger, Jörg T1 - X‑ray emission during the ablative processing of biological materials by ultrashort laser pulses JF - Applied Physics A N2 - The ablative laser processing with ultrashort pulsed laser beams may cause secondary emission of hazardous X-rays. While the effect has recently been proven to be considered in working safety regulations when processing technical materials, such as metals, the X-ray emission rates during the ablative processing of biological tissue materials are widely unexplored yet. Therefore, biological materials like water, isotonic saline solution, pig eyes, and human teeth were ablated with ultrashort laser pulses of 1030 nm wavelength, 600 fs pulse duration and 5 kHz pulse repetition rate, aiming to mimic typical surgery situations. Simultaneously, in-situ X-ray dose rate measurements were performed at a short distance from the plasma to display potential X-ray emission. For all four studied biological materials, our measurements prove the secondary emission of laser-induced X-rays. KW - Ultrashort pulsed laser KW - Laser-induced X-ray emission KW - Ophthalmology KW - Dentistry KW - Secondary hazard PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-569960 DO - https://doi.org/10.1007/s00339-023-06440-4 SN - 0947-8396 VL - 129 IS - 3 SP - 1 EP - 8 PB - Springer AN - OPUS4-56996 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Legall, Herbert A1 - Schwanke, Christoph A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - X-ray radiation protection aspects during ultrashort laser processing JF - Journal of Laser Applications N2 - Ultrashort pulse laser processing of materials allows for precise machining with high accuracy. By increasing the repetition rate to several 100 kHz, laser machining becomes quick and cost-effective. Ultrafast laser processing at high repetition rates and peak intensities above 10^13 W/cm^2 can cause a potential hazard by generation of unwanted x-ray radiation. Therefore, radiation protection must be considered. For 925 fs pulse duration at a center wavelength of 1030 nm, the x-ray emission in air at a repetition rate of 400 kHz was investigated up to a peak intensity of 2.6 × 10^14 W/cm^2. Based on the presented measurements, the properties of potential shielding materials will be discussed. By extending our previous works, a scaling of the x-ray radiation emission to higher peak intensities up to 10^15 W/cm^2 is described, and emitted x-ray doses are predicted. KW - Laser ablation KW - Ultrashort pulse laser processing KW - Laser-induced x-ray emission KW - Radiation protection PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-505677 DO - https://doi.org/10.2351/1.5134778 VL - 32 IS - 2 SP - 022004 AN - OPUS4-50567 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg A1 - Legall, Herbert A1 - Bonse, Jörn T1 - X-ray hazards and radiation protection aspects in ultrashort laser processing N2 - Ultrashort pulse laser micromachining at repetition rates of several hundreds of kHz allows a cost-effective high precision manufacturing, which makes this method attractive for many industrial applications. Upon exceeding a critical laser intensity, hard X-ray radiation is generated as a side effect. Even if the emitted X-ray dose per laser pulse is low, for currently available high-repetition-rate laser systems the accumulated X-ray dose becomes significant and radiation safety must be considered. Influences of the processing parameters are discussed and radiation protection aspects will be outlined T2 - AKL’22 – International Laser Technology Congress CY - Aachen, Germany DA - 04.05.2022 KW - Ultrashort pulse laser processing KW - X-ray emission KW - Radiation protection PY - 2022 AN - OPUS4-54805 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stolzenberg, U. A1 - Schmitt Rahner, M. A1 - Pullner, B. A1 - Legall, Herbert A1 - Bonse, Jörn A1 - Kluge, M. A1 - Ortner, A. A1 - Hoppe, B. A1 - Krüger, Jörg T1 - X-ray emission hazards from ultrashort pulsed laser material processing in an industrial setting JF - Materials N2 - Interactions between ultrashort laser pulses with intensities larger than 10^13 W/cm^2 and solids during material processing can lead to the emission of X-rays with photon energies above 5 keV, causing radiation hazards to operators. A framework for inspecting X-ray emission hazards during laser material processing has yet to be developed. One requirement for conducting radiation protection inspections is using a reference scenario, i.e., laser settings and process parameters that will lead to an almost constant and high level of X-ray emissions. To study the feasibility of setting up a reference scenario in practice, ambient dose rates and photon energies were measured using traceable measurement equipment in an industrial setting at SCHOTT AG. Ultrashort pulsed (USP) lasers with a maximum average power of 220 W provided the opportunity to measure X-ray emissions at laser peak intensities of up to 3.3 × 10^15 W/cm^2 at pulse durations of ~1 ps. The results indicate that increasing the laser peak intensity is insufficient to generate high dose rates. The investigations were affected by various constraints which prevented measuring high ambient dose rates. In this work, a list of issues which may be encountered when performing measurements at USP-laser machines in industrial settings is identified. KW - X-ray emission hazards KW - Ultrashort pulsed laser KW - Radiation protection KW - Industrial applications KW - Protection housing PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-538632 DO - https://doi.org/10.3390/ma14237163 SN - 1996-1944 VL - 14 SP - 1 EP - 17 PB - MDPI CY - Basel AN - OPUS4-53863 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg A1 - Legall, Herbert A1 - Schwanke, Christoph A1 - Bonse, Jörn T1 - X-ray emission during ultrashort pulse laser processing N2 - The industrial use of ultrashort laser pulses has made considerable progress in recent years. The reasons for this lie in the availability of high average powers at pulse repetition rates in the several 100 kHz range. The advantages of using ultrashort laser pulses in terms of processing precision can thus be fully exploited. However, high laser intensities on the workpiece can also lead to the generation of unwanted X-rays. Even if the emitted X-ray dose per pulse is low, the accumulated X-ray dose can become significant for high-repetition-rate laser systems so that X-ray exposure safety limits must be considered. The X-ray emission during ultrashort pulse laser processing was investigated for a pulse duration of 925 fs at 1030 nm wavelength and 400 kHz repetition rate. Industrially relevant materials such as steel, aluminum and glass were treated. Tungsten served as reference. X-ray spectra were recorded, and X-ray dose measurements were performed for laser treatment in air. For laser intensities > 2 × 10^13 W/cm2, X-ray doses exceeding the regulatory exposure limits for members of the public were found. Suitable X-ray protection strategies are proposed. T2 - SPIE Photonics West CY - San Francisco, USA DA - 02.02.2019 KW - Laser-induced X-ray emission KW - Ultrashort laser material interaction KW - Radiation protection PY - 2019 AN - OPUS4-47361 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Legall, Herbert A1 - Schwanke, Christoph A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - X-ray emission during ultrashort pulse laser processing T2 - Proceedings of SPIE - FRONTIERS IN ULTRAFAST OPTICS: BIOMEDICAL, SCIENTIFIC, AND INDUSTRIAL APPLICATIONS XIX N2 - The industrial use of ultrashort laser pulses has made considerable progress in recent years. The reasons for this lie in the availability of high average powers at pulse repetition rates in the several 100 kHz range. The advantages of using ultrashort laser pulses in terms of processing precision can thus be fully exploited. However, high laser intensities on the workpiece can also lead to the generation of unwanted X-rays. Even if the emitted X-ray dose per pulse is low, the accumulated X-ray dose can become significant for high-repetition-rate laser systems so that X-ray exposure safety limits must be considered. The X-ray emission during ultrashort pulse laser processing was investigated for a pulse duration of 925 fs at 1030 nm wavelength and 400 kHz repetition rate. Industrially relevant materials such as steel,aluminum and glass were treated. Tungsten served as reference. X-ray spectra were recorded, and X-ray dose measurements were performed for laser treatment in air. For laser intensities > 2 × 10^13 W/cm2, X-ray doses exceeding the regulatory exposure limits for members of the public were found. Suitable X-ray protection strategies are proposed. T2 - SPIE Photonics West CY - San Francisco, USA DA - 02.02.2019 KW - Laser-induced X-ray emission KW - Ultrashort laser material interaction KW - Radiation protection PY - 2019 SN - 978-1-5106-2459-7 DO - https://doi.org/10.1117/12.2516165 SN - 0277-786X SN - 1996-756X VL - 10908 SP - 1090802-1 EP - 1090802-7 PB - SPIE - The international society for optics and photonics CY - Bellingham, WA, USA AN - OPUS4-47510 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Legall, Herbert A1 - Schwanke, Christoph A1 - Pentzien, Simone A1 - Dittmar, G. A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - X-ray emission as a potential hazard during ultrashort pulse laser material processing JF - Applied physics A N2 - In laser machining with ultrashort laser pulses unwanted X-ray radiation in the keV range can be generated when a critical laser intensity is exceeded. Even if the emitted X-ray dose per pulse is low, high laser repetition rates can lead to an accumulation of X-ray doses beyond exposure safety limits. For 925 fs pulse duration at a center wavelength of 1030 nm, the X-ray emission was investigated up to an intensity of 2.6 × 10^14 W/cm2. The experiments were performed in air with a thin disk laser at a repetition rate of 400 kHz. X-ray spectra and doses were measured for various planar target materials covering a wide range of the periodic table from aluminum to tungsten. Without radiation shielding, the measured radiation doses at this high repetition rate clearly exceed the regulatory limits. Estimations for an adequate radiation shielding are provided. KW - Laser-induced X-ray emission KW - Ultrashort laser material interaction KW - Femtosecond laser KW - Radiation protection PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-448431 DO - https://doi.org/10.1007/s00339-018-1828-6 SN - 0947-8396 SN - 1432-0630 VL - 124 IS - 6 SP - Article 407, 1 EP - 8 PB - Springer AN - OPUS4-44843 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Böttcher, Katrin A1 - Schmitt Rahner, M. A1 - Stolzenberg, U. A1 - Kraft, Sebastian A1 - Bonse, Jörn A1 - Feist, C. A1 - Albrecht, D. A1 - Pullner, B. A1 - Krüger, Jörg T1 - Worst-case X-ray photon energies in ultrashort pulse laser processing JF - Materials N2 - Ultrashort pulse laser processing can result in the secondary generation of unwanted X-rays if a critical laser irradiance of about 10^13 W/cm^2 is exceeded. Spectral X-ray emissions were investigated during the processing of tungsten and steel using three complementary spectrometers (based on CdTe and silicon drift detectors) simultaneously for the identification of a worst-case spectral scenario. Therefore, maximum X-ray photon energies were determined, and corresponding dose equivalent rates were calculated. An ultrashort pulse laser workstation with a pulse duration of 274 fs, a center wavelength of 1030 nm, pulse repetition rates between 50 kHz and 200 kHz, and a Gaussian laser beam focused to a spot diameter of 33 µm was employed in a single pulse and burst laser operation mode. Different combinations of laser pulse energy and repetition rate were utilized, keeping the average laser power constant close to the maximum power of 20 W. Peak irradiances ranging from 7.3 × 10^13 W/cm^2 up to 3.0 × 10^14 W/cm^2 were used. The X-ray dose equivalent rate increases for lower repetition rates and higher pulse energy if a constant average power is used. Laser processing with burst mode significantly increases the dose rates and the X-ray photon energies. A maximum X-ray photon energy of about 40 keV was observed for burst mode processing of tungsten with a repetition rate of 50 kHz and a peak irradiance of 3 × 10^14 W/cm^2. KW - Ultrashort pulsed laser KW - X-ray emission KW - X-ray spectrum KW - X-ray energies KW - Radiation protection PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-566176 DO - https://doi.org/10.3390/ma15248996 VL - 15 IS - 24 SP - 1 EP - 17 PB - MDPI AN - OPUS4-56617 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg A1 - Kraft, S. A1 - Böttcher, Katrin A1 - Bonse, Jörn A1 - Schille, J. A1 - Löschner, U. T1 - Unwanted X-ray emission in ultrashort pulse laser processing: From metallic to biological materials N2 - Ultrashort laser pulses have become established in many industrial processes. Additionally, they are also an integral part of medical applications especially in ophthalmology and to some extent in dentistry. The availability of highly repetitive powerful laser sources and advanced laser beam control systems have favored these developments. However, the laser processing may be accompanied by the generation of unwanted X-rays. Small doses per laser pulse can accumulate to significant dose levels at high laser pulse repetition rates. Moreover, burst mode processing increases the X-ray dose rates compared to single pulse use and results in X-ray photon energies up to 40 keV for tungsten targets. For laser treatment of human teeth, clearly noticeable X-ray skin dose rates can be found. The paper summarizes the current state of the art in the field of undesired generation of X-ray radiation during ultrashort pulse laser processing in air. T2 - Lasers in Manufacturing 2023 (LiM 2023) CY - Munich, Germany DA - 26.06.2023 KW - Ultrashort laser pulses KW - Laser-induced X-ray emission KW - Secondary hazard PY - 2023 AN - OPUS4-57816 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kraft, S. A1 - Böttcher, Katrin A1 - Bonse, Jörn A1 - Schille, J. A1 - Löschner, U. A1 - Krüger, Jörg T1 - Unwanted X-ray emission in ultrashort pulse laser processing: From metallic to biological materials T2 - Proceedings of the Lasers in Manufacturing Conference 2023 N2 - X-rays can be generated as an unwanted side effect during ultrashort pulse laser material processing of technical work pieces and even biological samples with laser intensities above 10^13 W/cm^2. First studies demonstrate the need to address this effect in industrial as well as in medical applications. This secondary hazard should be considered in work safety and risk assessment. T2 - Lasers in Manufacturing 2023 (LiM 2023) CY - Munich, Germany DA - 26.06.2023 KW - Ultrashort pulse laser processing KW - Laser-induced X-ray emission KW - Secondary hazard PY - 2023 SP - LiM 2023 - 1 EP - LiM 2023 - 6 PB - Wissenschaftliche Gesellschaft Lasertechnik und Photonik e.V. (WLT) AN - OPUS4-58358 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Unerwünschte Röntgenemission bei der UKP-Lasermaterialbearbeitung N2 - Der Vortrag fasst aktuelle Aspekte zum unerwünschten Auftreten von Röntgenstrahlung bei der Ultrakurzpuls-Lasermaterialbearbeitung zusammen. Es werden Einflussparameter, Grenzwerte, Schutzmaßnahmen, Fragen der Abschirmung und rechtliche Gesichtspunkte diskutiert. T2 - Bayerische Laserschutztage 2022 CY - Online meeting DA - 18.01.2022 KW - Ultrakurze Laserpulse KW - Materialbearbeitung KW - Röntgenstrahlung KW - Strahlenschutz PY - 2022 AN - OPUS4-54259 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg A1 - Legall, H. A1 - Bonse, Jörn T1 - Undesired X-ray emission during ultrashort pulse laser material processing N2 - The use of ultrashort laser pulses for material processing in air has many advantages. Due to the progressive development in the laser sector, average powers in the kW range with pulse repetition rates exceeding the MHz-level are available. The machining with high-intensity laser pulses can be accompanied by the generation of a near-surface electron plasma due to absorption and ionization of the material, a subsequent plasma heating by the laser pulse, and finally an interaction of “hot” plasma electrons with the workpiece leading to continuous and characteristic X-ray radiation. The amount of this unwanted X-ray radiation is determined by the laser parameters (pulse duration, intensity, wavelength, polarization), the workpiece (atomic number, surface preparation), and the laser process management (scanning or stationary regime, laser turning). The use of laser intensities above 10^13 W/cm^2 in combination with laser pulse repetition rates in the few 100 kHz-range can lead to X-ray dose rates exceeding the permitted X-ray limits for members of the public. Especially the materials tungsten and steel show significant X-ray emission. Recently, the current state of the art in the field of undesired generation of X-ray radiation during ultrashort pulse laser processing in air was reviewed. In this presentation, important aspects of the measured X-ray doses, X-ray spectra, and practical issues of radiation protection are discussed. T2 - 28th International Conference on Advanced Laser Technologies (ALT'21) CY - Online meeting DA - 06.09.2021 KW - Ultrashort laser pulses KW - Material processing KW - X-ray emission KW - Radiation protection PY - 2021 AN - OPUS4-53241 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Wrobel, Jerzy A1 - Krüger, Jörg A1 - Kautek, Wolfgang T1 - Ultrashort-pulse laser ablation of indium phosphide in air JF - Applied physics A N2 - Ablation of indium phosphide wafers in air was performed with low repetition rate ultrashort laser pulses (130 fs, 10 Hz) of 800 nm wavelength. The relationships between the dimensions of the craters and the ablation parameters were analyzed. The ablation threshold fluence depends on the number of pulses applied to the same spot. The single-pulse ablation threshold value was estimated to be fth(1)=0.16 J/cm2. The dependence of the threshold fluence on the number of laser pulses indicates an incubation effect. Morphological and chemical changes of the ablated regions were characterized by means of scanning electron microscopy and Auger electron spectroscopy. PY - 2001 DO - https://doi.org/10.1007/s003390000596 SN - 0947-8396 VL - 72 IS - 1 SP - 89 EP - 94 PB - Springer CY - Berlin AN - OPUS4-1068 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 T2 - Polymers and light 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 - Kautek, Wolfgang A1 - Daminelli-Widany, Grazia A1 - Krüger, Jörg ED - Meunier, M. T1 - Ultrashort pulse laser interaction with anodic metal oxide layers in electrolyte contact T2 - Physics and chemistry of advanced laser materials processing N2 - The removal and accelerated corrosion monitoring of metal coating systems is of general interest in materials science and engineering technology. The femtosecond and nanosecond laser ablation and delamination at 800 nm and 532 nm, respectively, of anodic oxide layers on aluminium alloys in electrolyte contact were investigated. Laser-induced modifications of the oxide layer resulted in an ionic contact between electrolyte and metal, which produced a current transient and thus allowed the in-situ electrochemical monitoring of the modification. Oxide coatings with different optical properties, almost transparent and opaque, were examined. The transparent anodic oxides showed contrasting ablation mechanisms in the nanosecond and femtosecond pulse duration regime: nanosecond pulses caused spallation, whereas femtosecond treatment led to ablation. Current signals measured in the transparent film were consistent with light absorption below the metal-oxide interface and with film spallation. Irradiation of the opaque coating yielded ionic current transients within the so-called shock-affected-zone of the oxide layer. This investigation provided insight into the role of the penetration depth of light and the heat-affected zone, the extent of the shock-affected zone, and the defect formation in the coating and at the solid-solid interface between metal and oxide. T2 - Symposium D - European Materials Research Society CY - Strasbourg, France DA - 2002-06-18 PY - 2002 UR - http://www.emrs-strasbourg.com/files/pdf/2002_SPRING/02_Prog_Dv2.pdf N1 - Serientitel: Applied surface science – Series title: Applied surface science VL - 208/209.2003,1 IS - 1 SP - 1(?) PB - Elsevier CY - Amsterdam AN - OPUS4-1731 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Baudach, Steffen A1 - Bonse, Jörn A1 - Krüger, Jörg A1 - Kautek, Wolfgang T1 - Ultrashort pulse laser ablation of polycarbonate and polymethylmethacrylate JF - Applied surface science N2 - Ablation experiments with ultrashort laser pulses (pulse duration 150 fs, wavelength 800 nm) on polymers (PC, PMMA) relevant for biomedical technology have been performed in air. The lateral and vertical machining precision was evaluated by optical, atomic force and scanning electron microscopy. The ablation threshold reaches values in the range of 0.5–2.5 J/cm2 and depends significantly on the number of laser pulses applied to the same spot. The hole diameters are influenced by the laser fluence and the number of laser pulses. The relation between the ablation threshold and the number of laser pulses applied to the same spot is described in accordance with an incubation model. KW - Femtosecond laser ablation KW - Polymer KW - Polycarbonate KW - Polymethylmethacrylate PY - 2000 DO - https://doi.org/10.1016/S0169-4332(99)00474-2 SN - 0169-4332 SN - 1873-5584 VL - 154-155 SP - 555 EP - 560 PB - North-Holland CY - Amsterdam AN - OPUS4-803 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Ultrakurzpulslaseraktivitäten an der Bundesanstalt für Materialforschung und -prüfung N2 - Der Vortrag gibt einen Überblick zu aktuellen Projektaktivitäten im BAM-Fachbereich 6.4 Technologien mit Nanowerkstoffen. Der Einsatz von Femtosekunden-Laserpulsen zur Mikro- und Nanostrukturierung, für Prozessschritte in der Photovoltaik und zur Reinigung und Dekontamination von Oberflächen wird beschrieben. Darüber hinaus werden Laser-Zerstörschwellenmessungen erläutert. T2 - IFSW-Kolloquium CY - Universität Stuttgart, Stuttgart, Germany DA - 15.02.2017 KW - Ultrakurze Laserpulse KW - Femtosekundenlaser KW - Laser-Materialbearbeitung KW - Laserreinigung PY - 2017 AN - OPUS4-39170 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Ultrakurze Laserpulse für technische und biomedizinische Applikationen T2 - Workshop "Brillante Diodenlaser für neue Anwendungen in der Lasermaterialbearbeitung" T2 - Workshop "Brillante Diodenlaser für neue Anwendungen in der Lasermaterialbearbeitung" CY - Berlin, Germany DA - 2014-03-18 PY - 2014 AN - OPUS4-30579 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Ultrakurze Laserimpulse in der Mikromaterialbearbeitung T2 - Tag der Technik, Fachhochschule für Technik und Wirtschaft (FHTW) T2 - Tag der Technik, Fachhochschule für Technik und Wirtschaft (FHTW) CY - Berlin, Germany DA - 2006-05-19 PY - 2006 AN - OPUS4-12305 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Ultrakurze Laserimpulse in der Materialbearbeitung: Anwendungen und Sicherheitsaspekte N2 - Im Überblicksvortrag werden Untersuchungen zur Laser-Mikro- und Nanostrukturierung mit Femtosekunden-Laserimpulsen und ausgewählte Anwendungen, z.B. in der Photovoltaik und Biomedizin, vorgestellt. Aktuelle Fragestellungen zur sicheren Prozessführung, wie die mögliche Erzeugung von Röntgenstrahlung beim Laserbearbeitungsprozess und unerwünschte Partikelemissionen, werden aufgegriffen. T2 - Laserverbund Berlin Brandenburg, 89. Laserstammtisch Berlin Brandenburg - Laser für die Materialbearbeitung CY - Berlin, Germany DA - 17.09.2018 KW - Lasermikrobearbeitung KW - Femtosekundenlaser KW - Photovoltaik KW - Biomedizin KW - Lasersicherheit KW - Röntgenemission PY - 2018 AN - OPUS4-46077 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Abere, M. J. A1 - Zhong, M. A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Ultrafast laser-induced morphological transformations JF - MRS Bulletin N2 - Ultrafast laser processing can be used to realize various morphological surface transformations, ranging from direct contour shaping to large-area-surface functionalization via the generation of “self-ordered” micro- and nanostructures as well as their hierarchical hybrids. Irradiation with high-intensity laser pulses excites materials into extreme conditions, which then return to equilibrium through these unique surface transformations. In combination with suitable top-down or bottom-up manufacturing strategies, such laser-tailored surface morphologies open up new avenues toward the control of optical, chemical, and mechanical surface properties, featuring various technical applications especially in the fields of photovoltaics, tribology, and medicine. This article reviews recent efforts in the fundamental understanding of the formation of laser-induced surface micro- and nanostructures and discusses some of their emerging capabilities. KW - Laser ablation KW - Laser-induced periodic surface structures (LIPSS) KW - Surface morphology KW - Oxidation KW - Tribology PY - 2016 DO - https://doi.org/10.1557/mrs.2016.271 SN - 0883-7694 SN - 1938-1425 VL - 41 IS - 12 SP - 969 EP - 974 PB - Cambride University Press AN - OPUS4-38637 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Boeck, T. A1 - Schmidt, K. A1 - Lorenz, M. A1 - Rosenfeld, A. A1 - Rudolph, Pascale A1 - Krüger, Jörg A1 - Kautek, Wolfgang ED - Gobrecht, J. T1 - Ultra-short pulse laser seeding techniques for silicon crystallite growth on amorphous substrates T2 - Proceedings of the 11th Workshop on Quantum Solar Energy Conversion T2 - QUANTSOL 99 CY - Wildhaus, Switzerland DA - 1999-03-14 PY - 1999 SP - 1(?) EP - 3(?) AN - OPUS4-12041 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hertwig, Andreas A1 - Martin, S. A1 - Kautek, Wolfgang A1 - Krüger, Jörg ED - Maruray, L. T1 - Ultra-short Pulse Laser Safety - a Challenge to Materials Science T2 - Optical design and engineering II N2 - In this paper, safety-related experiments with ultra-short laser pulses (down to 30 fs) on various components (goggles, curtains) for laser protection are presented. The damage and failure behaviour of protective devices has been investigated dependent on practical conditions such as pulse duration, laser .uence, pulse number, and repetition rate. The e.ects of laser-irradiation on materials can be roughly divided into transient ones like laserinduced transmission (LIT) or short-lived colour centres and permanent damages like the stable colour centres and ablation. The former e.ects are particularly important for transparent devices like laser goggles. To obtain a complete overview on laser safety issues and the prevention of failure there are two important .elds of investigation: 1. the e.ects of laser radiation on human eyes and skin, and 2. on the possible protection materials. Both .elds have been addressed during the recently .nished German project SAFEST (safety aspects in femtosecond technology). The amount of safety data available in the ultrashort pulse region has been increased remarkably. This allows for a re-evaluation of known laser protection materials for this region of pulse durations and for the evaluation of new designs that promise high protection levels while being light-weight and convenient to use. T2 - Optical design and engineering II CY - Jena, Germany DA - 2005-09-13 PY - 2005 N1 - Serientitel: Proceedings of SPIE – Series title: Proceedings of SPIE IS - 5962 SP - 59622J-1 - 59622J-10 PB - SPIE CY - Bellingham AN - OPUS4-11593 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kirner, Sabrina V. A1 - Slachciak, Nadine A1 - Elert, Anna Maria A1 - Griepentrog, Michael A1 - Fischer, Daniel A1 - Hertwig, Andreas A1 - Sahre, Mario A1 - Dörfel, Ilona A1 - Sturm, Heinz A1 - Pentzien, Simone A1 - Koter, Robert A1 - Spaltmann, Dirk A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Tribological performance of titanium samples oxidized by fs-laser radiation, thermal heating, or electrochemical anodization JF - Applied Physics A N2 - Commercial grade-1 titanium samples (Ti, 99.6%) were treated using three alternative methods, (i) femtosecond laser processing, (ii) thermal heat treatment, and (iii) electrochemical anodization, respectively, resulting in the formation of differently conditioned superficial titanium oxide layers. The laser processing (i) was carried out by a Ti:sapphire laser (pulse duration 30 fs, central wavelength 790 nm, pulse repetition rate 1 kHz) in a regime of generating laser-induced periodic surface structures (LIPSS). The experimental conditions (laser fluence, spatial spot overlap) were optimized in a sample-scanning setup for the processing of several square-millimeters large surface areas covered homogeneously by these nanostructures. The differently oxidized titanium surfaces were characterized by optical microscopy, micro Raman spectroscopy, variable angle spectroscopic ellipsometry, and instrumented indentation testing. The tribological performance was characterized in the regime of mixed friction by reciprocating sliding tests against a sphere of hardened steel in fully formulated engine oil as lubricant. The specific tribological performance of the differently treated surfaces is discussed with respect to possible physical and chemical mechanisms. KW - Femtosecond laser KW - Titanium KW - Oxidation KW - Friction PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-445609 DO - https://doi.org/10.1007/s00339-018-1745-8 SN - 0947-8396 SN - 1432-0630 VL - 124 IS - 4 SP - 326, 1 EP - 10 PB - Springer-Verlag AN - OPUS4-44560 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Höhm, S. A1 - Koter, Robert A1 - Hartelt, Manfred A1 - Spaltmann, Dirk A1 - Pentzien, Simone A1 - Rosenfeld, A. A1 - Krüger, Jörg T1 - Tribological performance of sub-100-nm femtosecond laser-induced periodic surface structures on titanium JF - Applied Surface Science N2 - Sub-100-nm laser-induced periodic surface structures (LIPSS) were processed on bulk titanium (Ti) surfaces by femtosecond laser pulse irradiation in air (30 fs pulse duration, 790 nm wavelength). The laser peak fluence, the spatial spot overlap, and the number of overscans were optimized in a sample-scanning geometry in order to obtain large surface areas (5 mm × 5 mm) covered homogeneously by the LIPSS. The laser-processed regions were characterized by optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM). The friction coefficient of the nanostructured surfaces was tested during 1000 cycles under reciprocal sliding conditions (1 Hz, 1.0 N normal load) against a 10-mm diameter ball of hardened 100Cr6 steel, both in paraffin oil and in engine oil used as lubricants. Subsequently, the corresponding wear tracks were qualified by OM, SEM, and energy dispersive X-ray analyses (EDX). The results of the tribological tests are discussed and compared to that obtained for near wavelength-sized fs-LIPSS, processed under somewhat different irradiation conditions. Some constraints for a beneficial effect of LIPSS on the tribological performance are provided. KW - Femtosecond laser ablation KW - Laser-induced periodic surface structures, LIPSS KW - Friction KW - Wear KW - Nanostructures KW - Surface functionalization PY - 2016 UR - http://www.sciencedirect.com/science/article/pii/S0169433215026987 DO - https://doi.org/10.1016/j.apsusc.2015.11.019 SN - 0169-4332 SN - 1873-5584 VL - 374 SP - 190 EP - 196 PB - Elsevier B.V. CY - Amsterdam, Netherlands AN - OPUS4-35937 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Koter, Robert A1 - Hartelt, Manfred A1 - Spaltmann, Dirk A1 - Pentzien, Simone A1 - Höhm, S. A1 - Rosenfeld, A. A1 - Krüger, Jörg T1 - Tribological performance of femtosecond laser-induced periodic surface structures on titanium and a high toughness bearing steel JF - Applied surface science N2 - Laser-induced periodic surface structures (LIPSS, ripples) were processed on steel (X30CrMoN15-1) and titanium (Ti) surfaces by irradiation in air with linear polarized femtosecond laser pulses with a pulse duration of 30 fs at 790 nm wavelength. For the processing of large LIPSS covered surface areas (5 mm × 5 mm), the laser fluence and the spatial spot overlap were optimized in a sample-scanning geometry. The laser-processed surfaces were characterized by optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM). Spatial LIPSS periods between 450 and 600 nm were determined. The nanostructured surface regions were tribologically tested under reciprocal sliding conditions against a 10-mm diameter ball of hardened 100Cr6 steel. Paraffin oil and engine oil were used as lubricants for 1000 sliding cycles at 1 Hz with a normal load of 1.0 N. The corresponding wear tracks were analyzed by OM and SEM. In particular cases, the laser-generated nanostructures endured the tribological treatment. Simultaneously, a significant reduction of the friction coefficient and the wear was observed in the laser-irradiated (LIPSS-covered) areas when compared to the non-irradiated surface. The experiments reveal the potential benefit of laser surface structuring for tribological applications. KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser processing KW - Tribology KW - Metals PY - 2015 DO - https://doi.org/10.1016/j.apsusc.2014.08.111 SN - 0169-4332 SN - 1873-5584 VL - 336 SP - 21 EP - 27 PB - North-Holland CY - Amsterdam AN - OPUS4-32861 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mäder, M. A1 - Holle, H. A1 - Schreiner, M. A1 - Pentzien, Simone A1 - Krüger, Jörg A1 - Kautek, Wolfgang ED - Johann Nimmrichter, ED - Kautek, Wolfgang ED - Manfred Schreiner, T1 - Traditional and laser cleaning methods of historic picture post cards T2 - LACONA VI - Lasers in the conservation of artworks (Proceedings) T2 - LACONA VI CY - Vienna, Austria DA - 2005-09-21 KW - Laser KW - Cleaning KW - Picture Post Card PY - 2007 SN - 978-3-540-72129-1 SN - 0930-8989 N1 - Serientitel: Springer proceedings in physics – Series title: Springer proceedings in physics IS - 116 SP - 281 EP - 286 PB - Springer CY - Berlin AN - OPUS4-16378 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Eberstein, M. A1 - Geier, M. A1 - Grießmann, H. A1 - Partsch, U. A1 - Voelkel, L. A1 - Böhme, R. A1 - Pentzien, Simone A1 - Koter, Robert A1 - Mann, Guido A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - Towards an industrial laser doping process for the selective emitter using phosphoric acid as dopant T2 - 26th European photovoltaic solar energy conference and exhibition (Proceedings) N2 - Different laser supported approaches have already been realized, proving the great potential of laserdoped selective emitters (LDSE). However, it is challenging to establish a low-cost process by using pulsed laser tools. So far a single-step process only leads to satisfying results utilizing cw-lasers. In this paper we have examined a two-step process to produce laser-doped selective emitters on multicrystalline textured standard silicon photovoltaic wafers (90-Ω/sq-Emitter, SiN-antireflection coating (ARC)). The precise ARC removal by near-infrared fs-laser pulses (30 fs, 800 nm), and the doping of uncoated silicon wafers by ns-laser pulses (8 ns, 532 nm) were systematically investigated. In the fs-experiment, optimum conditions for ARC removal were identified. In the nsexperiments under suitable conditions (melting regime), the phosphorous concentration underneath the wafer surface was significantly increased and the sheet resistance was reduced by nearly a factor of two. Moreover, electrical measurements on fired metallization fingers deposited on the laser processed wafers showed low contact resistances. Hence, wafer conditioning with combined fs-laser- and ns-laser-processes are expected to be a promising technology for producing selective emitters. T2 - 26th European photovoltaic solar energy conference and exhibition CY - Hamburg, Germany DA - 05.09.2011 KW - Laser processing KW - Doping KW - Selective emitter KW - Multicrystalline silicon PY - 2011 SN - 3-936338-27-2 DO - https://doi.org/10.4229/26thEUPVSEC2011-2BV.1.2 SP - 1220 EP - 1223 AN - OPUS4-24996 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg A1 - Symietz, Christian A1 - Lehmann, Erhard A1 - Gildenhaar, Renate A1 - Koter, Robert A1 - Berger, Georg 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 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 - Legall, Herbert A1 - Schwanke, Christoph A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - The influence of processing parameters on X‑ray emission during ultra‑short pulse laser machining JF - Applied Physics A N2 - During ultra-short laser material processing at high laser pulse repetition rates unwanted X-ray radiation can be generated in a quantity that may constitute a potential risk for health. An adequate X-ray radiation protection requires a thoroughly understanding of the influence of the laser processing parameters on the generation of X-ray radiation. In the present work, the generated X-ray dose during laser machining was investigated in air for varying beam scanning conditions at a pulse duration of 925 fs, a center wavelength of 1030 nm and a laser peak intensity of 2.6 × 10^14 W/cm^2. The X-ray radiation dose and the corresponding spectral X-ray emission were investigated in dependence on the laser’s pulse repetition rate and on the beam scanning speed. The results show a strong dependence of the X-ray emission on these laser processing parameters. KW - Laser-induced X-ray emission KW - Ultrashort laser material interaction KW - Femtosecond laser KW - Radiation protection PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-486441 DO - https://doi.org/10.1007/s00339-019-2827-y SN - 0947-8396 SN - 1432-0630 VL - 125 IS - 8 SP - 570, 1 EP - 8 PB - Springer AN - OPUS4-48644 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 T2 - LACONA VIII - Lasers in the conservation of artworks (Proceedings) 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 A1 - Pentzien, Simone A1 - Pucko Mencigar, D. A1 - Strilic, M. T1 - The influence of paper type and state of degradation on laser cleaning of artifically soiled paper T2 - Konferenz LACONA 8 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 - Krüger, Jörg A1 - Kautek, Wolfgang T1 - The Femtosecond Pulse Laser: a New Tool for Micromachining JF - Laser physics KW - Femtosekundenlaser KW - Mikrobearbeitung PY - 1999 SN - 1054-660X SN - 1531-8494 IS - 9,1 SP - 30 EP - 40 PB - MAIK Nauka/Interperiodica Publ. CY - Moscow AN - OPUS4-712 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Birgit Angelika A1 - Ziemann, M. A A1 - Pentzien, Simone A1 - Gabsch, T. A1 - Koch, W. A1 - Krüger, Jörg T1 - Technical analysis of a Central Asian wall painting detached from a Buddhist cave temple on the northern Silk Road JF - Studies in Conservation N2 - A great number of Central Asian wall paintings, archeological materials, architectural fragments, and textiles, as well as painting fragments on silk and paper, make up the so called Turfan Collection at the Asian Art Museum in Berlin. The largest part of the collection comes from the Kucha region, a very important cultural center in the third to ninth centuries. Between 1902 and 1914, four German expeditions traveled along the northern Silk Road. During these expeditions, wall paintings were detached from their original settings in Buddhist cave complexes. This paper reports a technical study of a wall painting, existing in eight fragments, from the Buddhist cave no. 40 (Ritterhöhle). Its original painted surface is soot blackened and largely illegible. Grünwedel, leader of the first and third expeditions, described the almost complete destruction of the rediscovered temple complex and evidence of fire damage. The aim of this case study is to identify the materials used for the wall paintings. Furthermore, soot deposits as well as materials from conservation interventions were of interest. Non-invasive analyses were preferred but a limited number of samples were taken to provide more precise information on the painting technique. By employing optical and scanning electron microscopy, energy dispersive X-ray spectroscopy, micro X-ray fluorescence spectroscopy, X-ray diffraction analysis, and Raman spectroscopy, a layer sequence of earthen render, a ground layer made of gypsum, and a paint layer containing a variety of inorganic pigments were identified. KW - Wall paintings KW - Central Asia KW - Silk Road KW - Pigments KW - Microscopy PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-357297 DO - https://doi.org/10.1179/2047058414Y.0000000152 VL - 61 IS - 2 SP - 113 EP - 122 PB - Routledge Taylor & Francis Group CY - London AN - OPUS4-35729 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cubero, A. A1 - Martínez, E. A1 - Angurel, L.A. A1 - de la Fuente, G.F. A1 - Navarro, R. A1 - Legall, Herbert A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Surface superconductivity changes of niobium sheets by femtosecond laser-induced periodic nanostructures JF - Nanomaterials N2 - Irradiation with ultra-short (femtosecond) laser beams enables the generation of sub-wavelength laser-induced periodic surface structures (LIPSS) over large areas with controlled spatial periodicity, orientation, and depths affecting only a material layer on the sub-micrometer scale. This study reports on how fs-laser irradiation of commercially available Nb foil samples affects their superconducting behavior. DC magnetization and AC susceptibility measurements at cryogenic temperatures and with magnetic fields of different amplitude and orientation are thus analyzed and reported. This study pays special attention to the surface superconducting layer that persists above the upper critical magnetic field strength Hc2, and disappears at a higher nucleation field strength Hc3. Characteristic changes were distinguished between the surface properties of the laser-irradiated samples, as compared to the corresponding reference samples (non-irradiated). Clear correlations have been observed between the surface nanostructures and the nucleation field Hc3, which depends on the relative orientation of the magnetic field and the surface patterns developed by the laser irradiation. KW - Niobium KW - Surface superconductivity KW - Laser-induced periodic surface structures (LIPSS) KW - Nanostructures PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-518462 DO - https://doi.org/10.3390/nano10122525 SN - 2079-4991 VL - 10(12) IS - Special issue "Laser-generated periodic nanostructures" SP - 1 EP - 16 PB - MDPI CY - Basel AN - OPUS4-51846 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn A1 - Kirner, Sabrina V. A1 - Epperlein, Nadja A1 - Spaltmann, Dirk A1 - Krüger, Jörg T1 - Surface functionalization by laser-induced periodic surface structures (LIPSS) T2 - 10th Stuttgart Laser Technology Forum 2018, Book of Abstracts N2 - In this contribution the mechanisms of formation and current applications of LIPSS are reviewed, including the colorization of technical surfaces, the control of surface wetting properties, the mimicry of the natural texture of animal integuments, the tailoring of surface colonization by bacterial biofilms, and the improvement of the tribological performance of nanostructured metal surfaces. T2 - 10th Stuttgart Laser Technology Forum 2018 CY - Stuttgart, Germany DA - 05.06.2018 KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser ablation KW - Surface functionalization KW - Wetting KW - Tribology KW - Biofilms PY - 2018 SP - 35 AN - OPUS4-45128 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Florian, Camilo A1 - Kirner, Sabrina V. A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Surface functionalization by laser-induced periodic surface structures JF - Journal of Laser Applications N2 - In recent years, the improved understanding of the formation of laser-induced periodic surface structures (LIPSS) has led to an emerging variety of applications that modify the optical, mechanical, and chemical properties of many materials. Such structures strongly depend on the laser beam polarization and are formed usually after irradiation with ultrashort linearly polarized laser pulses. The most accepted explanation for the origin of the structures is based on the interference of the incident laser radiation with electromagnetic surface waves that propagate or scatter at the surface of the irradiated materials. This leads to an intensity modulation that is finally responsible for the selective ablation in the form of parallel structures with periods ranging from hundreds of nanometers up to some micrometers. The versatility when forming such structures is based on the high reproducibility with different wavelengths, pulse durations and repetition rate laser sources, customized micro- and nanometric spatial resolutions, and compatibility with industrially relevant processing speeds when combined with fast scanning devices. In this contribution, we review the latest applications in the rapidly emerging field of surface functionalization through LIPSS, including biomimetic functionalities on fluid transport, control of the wetting properties, specific optical responses in technical materials, improvement of tribological performance on metallic surfaces, and bacterial and cell growth for medical devices, among many others. KW - Laser-induced periodic surface structures (LIPSS) KW - Laser processing KW - Surface functionalization KW - Applications PY - 2020 DO - https://doi.org/10.2351/7.0000103 SN - 1938-1387 VL - 32 IS - 2 SP - 022063 PB - Laser Institute of America AN - OPUS4-50780 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Florian, Camilo A1 - Kirner, Sabrina V. A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Surface functionalization by laser-induced periodic surface structures T2 - 2019 ICALEO Conference Proceedings N2 - In recent years, the improved understanding of the formation of laser-induced periodic surface structures (LIPSS) has led to an emerging variety of applications that modify the optical, mechanical and chemical properties of many materials. Such structures strongly depend on the laser beam polarization and are formed usually after irradiation with ultrashort linearly polarized laser pulses. The most accepted explanation for the origin of the structures is based on the interference of the incident laser radiation with electromagnetic surface waves that propagate or scatter at the surface of the irradiated materials. This leads to an intensity modulation that is finally responsible for the selective ablation in the form of parallel structures with periods ranging from hundreds of nanometers up to some micrometers. The versatility when forming such structures is based on the high reproducibility with different wavelength, pulse duration and repetition rate laser sources, customized micro- and nanometric spatial resolutions, and the compatibility with industrially relevant processing speeds when combined with fast scanning devices. In this contribution, we review the latest applications in the rapidly emerging field of surface functionalization through LIPSS, including biomimetic functionalities on fluid transport, control of the wetting properties, specific optical responses in technical materials, improvement of tribological performance on metallic surfaces and bacterial and cell growth for medical devices, among many others. T2 - 38th International Congress on Applications of Lasers & Electro-Optics CY - Orlando, FL, USA DA - 07.10.2019 KW - Laser-induced periodic surface structures (LIPSS) KW - Laser processing KW - Surface functionalization KW - Applications PY - 2019 SN - 978-1-940168-1-42 SP - Paper Nano 404 AN - OPUS4-50070 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hertwig, Andreas A1 - Martin, Sven A1 - Krüger, Jörg A1 - Kautek, Wolfgang T1 - Surface damage and color centers generated by femtosecond pulses in borosilicate glass and silica JF - Applied physics A N2 - Color center generation by femtosecond laser pulses (30 fs) is observed in a fluence range below the damage threshold in an alkali-free barium borosilicate (BBS) glass, and in a thin layer of SiO2 on a fused silica substrate. The color centers are characterized spectroscopically. The optical density of the color centers in BBS glass is by two orders of magnitude higher than that in silica. A healing process with a time constant of about 30 h can be found. PY - 2004 UR - http://www.sciencedirect.com/science/journal/0926860X DO - https://doi.org/10.1007/s00339-004-2634-x SN - 0947-8396 VL - 79 SP - 1075 EP - 1077 PB - Springer CY - Berlin AN - OPUS4-11047 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krivenko, A.G. A1 - Krüger, Jörg A1 - Kautek, Wolfgang A1 - Benderskii, V.A. T1 - Subpicosecond-Pulse-Laser-Induced Electron Emission from Mercury and Silver into Aqueous Electrolytes JF - Berichte der Bunsen-Gesellschaft PY - 1995 SN - 0005-9021 VL - 99 IS - 12 SP - 1489 EP - 1494 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-11782 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - v. Woedtke, T. A1 - Abel, P. A1 - Krüger, Jörg A1 - Kautek, Wolfgang T1 - Subpicosecond-pulse laser microstructuring for enhanced reproducibility of biosensors JF - Sensors and actuators B: Chemical N2 - Curved substrates can be micro-structured by laser ablation, which is not possible with standard lithographic methods. The novel femtosecond-pulse laser technique allows the production of defined and reproducible micro-perforations of originally analyte-impermeable membranes. The trans-membrane analyte flux can be controlled both by the variation of the laser focus diameter resulting in different areas of single perforations, and the number of perforations in arrays on small membrane areas. This leads to a higher degree of variability as well as reproducibility of the diffusion qualities of sensor membranes, and marks the main innovation with this technique compared to the hand-made mechanical perforation by specially grinded needles used up to now. Touchless micro-perforation of small membrane areas with negligible heat damage of the structures adjacent to the perforation allows the application of ‘analyte door’ membranes directly onto curved surfaces of miniaturized needle-sensors assigned for in vivo glucose monitoring, for the first time. KW - Biosensor KW - Glucose KW - Membrane perforation KW - Subpicosecond laser ablation KW - Reproducibility PY - 1997 DO - https://doi.org/10.1016/S0925-4005(97)80330-9 SN - 0925-4005 SN - 1873-3077 VL - 42 IS - 3 SP - 151 EP - 156 PB - Elsevier CY - Amsterdam [u.a.] AN - OPUS4-11513 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krivenko, A.G. A1 - Kautek, Wolfgang A1 - Krüger, Jörg A1 - Benderskii, V.A. T1 - Subpicosecond Emission from Mercury and Silver into Electrolyte Solution: An Experimental Study JF - Russian journal of electrochemistry PY - 1997 SN - 0038-5387 SN - 1023-1935 VL - 33 IS - 4 SP - 394 EP - 400 PB - MAIK Nauka/Interperiodica Publ. CY - Moscow AN - OPUS4-11781 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Höhm, S. A1 - Rosenfeld, A. A1 - Krüger, Jörg T1 - Sub-100-nm laser-induced periodic surface structures upon irradiation of titanium by Ti:sapphire femtosecond laser pulses in air JF - Applied physics A N2 - The formation of laser-induced periodic surface structures (LIPSS) on titanium upon irradiation with linearly polarized femtosecond (fs) laser pulses (τ = 30 fs, λ = 790 nm) in an air environment is studied experimentally and theoretically. In the experiments, the dependence on the laser fluence and the number of laser pulses per irradiation spot has been analyzed. For a moderate number of laser pulses (N < 1000) and at fluences between ~0.09 and ~0.35 J/cm², predominantly low-spatial-frequency-LIPSS with periods between 400 nm and 800 nm are observed perpendicular to the polarization. In a narrow fluence range between 0.05 and 0.09 J/cm², high-spatial-frequency-LIPSS with sub-100-nm spatial periods (~λ/10) can be generated with an orientation parallel to the polarization (N = 50). These experimental results are complemented by calculations based on a theoretical LIPSS model and compared to the present literature. PY - 2013 DO - https://doi.org/10.1007/s00339-012-7140-y SN - 0947-8396 VL - 110 IS - 3 SP - 547 EP - 551 PB - Springer CY - Berlin AN - OPUS4-27788 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - Structuring of thin films by ultrashort laser pulses JF - Applied physics A N2 - Modern life and global communication would not be possible without technologically tailored thin films; they are omnipresent in daily life applications. In most cases, the films are deposited entirely at the carrying substrates in a specific processing step of the device or sample. In some cases, however, removal or modification must be performed locally, i.e., site-controlled and material selective through an additional laser processing step. For that ultrashort laser pulses with durations in the femtosecond and picosecond range can provide unique advantages and capabilities in industrially scalable schemes. This article reviews the current state of the research and corresponding industrial transfer related to the structuring of thin films by ultrashort pulsed lasers. It focuses on the pertinent historic developments, reveals the relevant physical and chemical effects, explores the ultimate limits, and discusses selected industrial and scientific applications. KW - Thin films KW - Laser processing KW - Ultrashort lasers KW - Laser damage KW - Femtosecond laser ablation PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-565732 DO - https://doi.org/10.1007/s00339-022-06229-x SN - 0947-8396 SN - 1432-0630 VL - 129 IS - 1 SP - 1 EP - 38 PB - Springer CY - Berlin AN - OPUS4-56573 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Krüger, Jörg A1 - Kautek, Wolfgang A1 - Lenzner, M. A1 - Sartania, S. A1 - Spielmann, C. A1 - Krausz, F. ED - Dubowski, J. T1 - Structuring of dielectric and metallic materials with ultrashort laser pulses between 20 fs and 3 ps T2 - Laser applications in microelectronic and optoelectronic manufacturing II N2 - Laser-micromachining of barium aluminum borosilicate glass, fused silica and stainless steel has been extended down to a pulse duration of 20 fs generated by a Ti:sapphire laser system at a wavelength of 0.8 micrometer. A systematic study shows that, below 100 fs, an enhanced precision and a substantial decrease of the ablation threshold fluence in comparison to pulse laser processing with pulses in the picosecond and nanosecond range could be achieved. The physical mechanism and the technical relevance of this novel microtechnology is discussed. T2 - Conference CY - San José, CA, USA DA - 1997-02-10 KW - Ablation KW - Laser processing KW - Micromachining KW - Structuring KW - Femtosecond pulse laser KW - Glass KW - Silica KW - Steel PY - 1997 SN - 0-8194-2402-1 DO - https://doi.org/10.1117/12.273740 SN - 1605-7422 N1 - Serientitel: SPIE proceedings series – Series title: SPIE proceedings series IS - 2991 SP - 40 EP - 47 PB - SPIE CY - Bellingham, Wash. AN - OPUS4-11893 LA - eng 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 JF - Galvanotechnik 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 - CONF A1 - Krüger, Jörg T1 - Strahlenschutz beim Umgang mit Ultrakurzpuls-Lasern N2 - Ultrakurzpuls-Lasertechnik ist heute der Schlüssel für eine Vielzahl von Anwendungen in der industriellen Lasermaterialbearbeitung. Beim Einsatz hoher Laser-Intensitäten kann allerdings unerwünschte Röntgenstrahlung erzeugt werden. Die Röntgendosis und Energieverteilung ist von Laser-, Material- und Prozessparametern abhängig. Es können Röntgendosen über den erlaubten Grenzwerten für die Exposition des Menschen erreicht werden. T2 - Kolloquium des Bundesamtes für Strahlenschutz (BfS) CY - Online meeting DA - 29.09.2022 KW - Ultrakurze Laserpulse KW - Materialbearbeitung KW - Röntgenstrahlung KW - Strahlenschutz KW - Abschirmung PY - 2022 AN - OPUS4-55893 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Strahlenexpositionen bei der Anwendung von Ultrakurzpulslasern in der Medizin N2 - Die Erzeugung unerwünschter Röntgenstrahlung bei der Ultrakurzpulslaser-Bearbeitung von Cornea und Zahnmaterial wurde untersucht. Laser-induzierte Dosisleistungen über dem natürlichen Hintergrund wurden gemessen. Mögliche Strahlenexpositionen in realen Anwendungen am Menschen wurden im Online-Vortrag diskutiert. Im Rahmen des vom BfS geförderten Projektes haben die Hochschule Mittweida und die BAM gemeinsam Untersuchungen durchgeführt. T2 - Kolloquium des Bundesamtes für Strahlenschutz (BfS) CY - Online meeting DA - 18.04.2023 KW - Ultrakurzpulslaser KW - Laser-induzierte Röntgenstrahlung KW - Medizinische Anwendung KW - Auge KW - Zahn PY - 2023 AN - OPUS4-57362 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Symietz, Christian A1 - Krüger, Jörg ED - Vilar, Rui T1 - Stability of laser surface modified implants T2 - Laser Surface Modification of Biomaterials: Techniques and applications N2 - A new technique to fix bioceramic powder on a titanium alloy by using femtosecond laser pulses is presented. It is shown that gentle fixation of a bioactive dielectric material on a metallic model implant is successful. This is potentially a new tool for the improvement of bone prostheses. An advantage of the ultrashort pulses is the very low heat influx into the whole sample. There is only a very thin interaction zone during the fixing, which is the metal surface in contact with the ceramic layer. Neither the fixed ceramic particles nor the major part of the metal suffer any modification. The stability of the model implant (ceramic on metal) is investigated by rotating bending fatigue tests. No indication of a reduction of the mechanical stability compared to untreated metallic reference samples was found. KW - Bone implant KW - Calcium phosphate coating KW - Femtosecond laser KW - Laser-induced fixation KW - Titanium alloy PY - 2016 SN - 978-0-08-100883-6 SN - 978-0-08-100942-0 DO - https://doi.org/10.1016/B978-0-08-100883-6.00004-6 SN - 2049-9485 IS - 111 SP - Chapter 4, 127 EP - 143 PB - Elsevier ET - 1st edition AN - OPUS4-36790 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 JF - Applied physics A 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 - Rudenko, A. A1 - Colombier, J.-P. A1 - Höhm, S. A1 - Rosenfeld, A. A1 - Krüger, Jörg A1 - Bonse, Jörn A1 - Itina, T.E. T1 - Spontaneous periodic ordering on the surface and in the bulk of dielectrics irradiated by ultrafast laser: a shared electromagnetic origin JF - Scientific Reports N2 - Periodic self-organization of matter beyond the diffraction limit is a puzzling phenomenon, typical both for surface and bulk ultrashort laser processing. Here we compare the mechanisms of periodic nanostructure formation on the surface and in the bulk of fused silica. We show that volume nanogratings and surface nanoripples having subwavelength periodicity and oriented perpendicular to the laser polarization share the same electromagnetic origin. The nanostructure orientation is defined by the near-field local enhancement in the vicinity of the inhomogeneous scattering centers. The periodicity is attributed to the coherent superposition of the waves scattered at inhomogeneities. Numerical calculations also support the multipulse accumulation nature of nanogratings formation on the surface and inside fused silica. Laser surface processing by multiple laser pulses promotes the transition from the high spatial frequency perpendicularly oriented nanoripples to the low spatial frequency ripples, parallel or perpendicular to the laser polarization. The latter structures also share the electromagnetic origin, but are related to the incident field interference with the scattered far-field of rough non-metallic or transiently metallic surfaces. The characteristic ripple appearances are predicted by combined electromagnetic and thermo-mechanical approaches and supported by SEM images of the final surface morphology and by time-resolved pump-probe diffraction measurements. KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser KW - Nanostructures KW - Dielectrics KW - Electromagnetic scattering PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-421747 UR - https://www.nature.com/articles/s41598-017-12502-4 DO - https://doi.org/10.1038/s41598-017-12502-4 SN - 2045-2322 VL - 7 SP - Article 12306, 1 EP - 14 PB - Springer Nature AN - OPUS4-42174 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kautek, Wolfgang A1 - Krüger, Jörg A1 - Lenzner, Matthias A1 - Martin, Sven A1 - Lenner, M. A1 - Spielmann, C. A1 - Fiedler, A. ED - Meunier, M. T1 - Single- and multi-pulse femtosecond laser ablation of optical filter materials T2 - Physics and chemistry of advanced laser materials processing N2 - Commercially available absorption filters (Schott BG18 and BG36) were investigated with respect to their single- and multi-pulse ablation threshold using laser pulses from a Ti:Sapphire laser in the range between 30 and 340 fs. It could be observed, that the threshold fluence decreases for shorter pulse durations. The similarity of the measured multi-pulse threshold fluences with those of undoped glass material (around 1 J/cm^2 for a pulse duration of 30 fs) suggests that, for very short pulses, the threshold is independent on the doping level and therefore, linear absorption does not significantly contribute to laser-induced damage. For >100 pulses per spot and all pulse durations applied, the threshold fluences saturate. This independence on the number of applied pulses leads to technically relevant damage threshold values. T2 - Symposium D - European Materials Research Society CY - Strasbourg, France DA - 2002-06-18 PY - 2002 UR - http://www.emrs-strasbourg.com/files/pdf/2002_SPRING/02_Prog_Dv2.pdf N1 - Serientitel: Applied surface science – Series title: Applied surface science VL - 208/209.2003,1 IS - 1 SP - 1(?) PB - Elsevier CY - Amsterdam AN - OPUS4-1588 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Jörg A1 - Lenzner, Matthias A1 - Martin, Sven A1 - Lenner, M. A1 - Spielmann, Ch. A1 - Fiedler, A. A1 - Kautek, Wolfgang T1 - Single- and multi-pulse femtosecond laser ablation of optical filter materials JF - Applied surface science N2 - Ablation experiments employing Ti:sapphire laser pulses with durations from 30 to 340 fs (centre wavelength 800 nm, repetition rate 1 kHz) were performed in air. Absorbing filters (Schott BG18 and BG36) served as targets. The direct focusing technique was used under single- and multi-pulse irradiation conditions. Ablation threshold fluences were determined from a semi-logarithmic plot of the ablation crater diameter versus laser fluence. The threshold fluence decreases for a shorter pulse duration and an increasing number of pulses. The multi-pulse ablation threshold fluences are similar to those of undoped glass material (~1 J cm-2). That means that the multi-pulse ablation threshold is independent on the doping level of the filters. For more than 100 pulses per spot and all pulse durations applied, the threshold fluence is practically constant. This leads to technically relevant ablation threshold values. KW - Damage KW - Femtosecond laser ablation KW - Filter KW - Incubation KW - Laser safety KW - Threshold PY - 2003 DO - https://doi.org/10.1016/S0169-4332(02)01389-2 SN - 0169-4332 SN - 1873-5584 VL - 208-209 SP - 233 EP - 237 PB - North-Holland CY - Amsterdam AN - OPUS4-11545 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Florian, Camilo A1 - Fischer, Daniel A1 - Freiberg, K. A1 - Duwe, M. A1 - Sahre, Mario A1 - Schneider, S. A1 - Hertwig, Andreas A1 - Krüger, Jörg A1 - Rettenmayr, M. A1 - Beck, Uwe A1 - Undisz, A. A1 - Bonse, Jörn T1 - Single Femtosecond Laser-Pulse-Induced Superficial Amorphization and Re-Crystallization of Silicon JF - Materials N2 - Superficial amorphization and re-crystallization of silicon in <111> and <100> orientation after irradiation by femtosecond laser pulses (790 nm, 30 fs) are studied using optical imaging and transmission electron microscopy. Spectroscopic imaging ellipsometry (SIE) allows fast data acquisition at multiple wavelengths and provides experimental data for calculating nanometric amorphous layer thickness profiles with micrometric lateral resolution based on a thin-film layer model. For a radially Gaussian laser beam and at moderate peak fluences above the melting and below the ablation thresholds, laterally parabolic amorphous layer profiles with maximum thicknesses of several tens of nanometers were quantitatively attained. The accuracy of the calculations is verified experimentally by high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (STEM-EDX). Along with topographic information obtained by atomic force microscopy (AFM), a comprehensive picture of the superficial re-solidification of silicon after local melting by femtosecond laser pulses is drawn. KW - Femtosecond laser KW - Silicon KW - Amorphization KW - Crystallization KW - Spectroscopic imaging ellipsometry PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523687 UR - https://www.mdpi.com/1996-1944/14/7/1651 DO - https://doi.org/10.3390/ma14071651 SN - 1996-1944 VL - 14 IS - 7 SP - 1651-1 EP - 1651-21 PB - MDPI AG CY - Basel, Switzerland AN - OPUS4-52368 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Sicherheitsaspekte bei der Nutzung von Laserstrahlung T2 - 11. Salzburger Ophthalmologisches Symposium T2 - 11. Salzburger Ophthalmologisches Symposium CY - Salzburg, Austria DA - 2006-04-07 PY - 2006 AN - OPUS4-12203 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Sicherheit in der Anwendung der Femtosekunden-Lasertechnologie T2 - Mitgliederversammlung Laserverbund Berlin/Brandenburg T2 - Mitgliederversammlung Laserverbund Berlin/Brandenburg CY - Berlin, Germany DA - 2007-01-18 PY - 2007 AN - OPUS4-14455 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bunte, J. A1 - Barcikowski, S. A1 - Burmester, T. A1 - Püster, T. A1 - Hertwig, Andreas A1 - Kautek, Wolfgang A1 - Krüger, Jörg A1 - Martin, Sven A1 - Spielmann, C. A1 - Lenner, M. A1 - Brose, M. T1 - Sicherer Umgang mit Ultrakurzpuls-Lasern, Teil 2: Sekundäre Gefährdungen JF - Laser-Magazin PY - 2005 SN - 0945-8875 IS - 4 SP - 13 EP - 18 PB - Magazin-Verl. CY - Bad Nenndorf AN - OPUS4-11002 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bunte, J. A1 - Barcikowski, S. A1 - Burmester, T. A1 - Püster, T. A1 - Hertwig, Andreas A1 - Kautek, Wolfgang A1 - Krüger, Jörg A1 - Martin, Sven A1 - Spielmann, C. A1 - Lenner, M. A1 - Brose, M. T1 - Sicherer Umgang mit Ultrakurzpuls-Lasern, Teil 1: Primäre Gefährdungen JF - Laser-Magazin PY - 2005 SN - 0945-8875 IS - 2 SP - 6 EP - 11 PB - Magazin-Verl. CY - Bad Nenndorf AN - OPUS4-11001 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Short pulse laser processing: safety aspects T2 - Bereichsseminar A - Max Born Institut Berlin T2 - Bereichsseminar A - Max Born Institut Berlin CY - Berlin, Germany DA - 2006-11-30 PY - 2006 AN - OPUS4-13779 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sorg, N. A1 - Krüger, Jörg A1 - Kautek, Wolfgang T1 - SHG Measurements of n-Si(111)/aqueous Solution Interfaces JF - Berichte der Bunsen-Gesellschaft PY - 1993 SN - 0005-9021 VL - 97 IS - 3 SP - 402 EP - 406 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-11658 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gappenach, C. A1 - Krüger, Jörg A1 - Offenhäuser, F. A1 - Pintaske, S. A1 - Krauß, H.-J. T1 - Selecting laser eye protectors - a helping hand JF - Advanced optical technologies N2 - The European laser safety standards EN 207, EN 208, and EN 12254 each contain an annex B, which serves as a guidance for the selection of products. These annexes are informative only and are therefore not binding. As there are a variety of hazard scenarios, it is not recommended to change these annexes to a normative status, through which they would become mandatory. Instead, it is recommended to allow users to apply their own skills and know-how in selecting appropriate products, justifying where and why they deviate from the guidance in the standards. This paper explains the background on which the guidance for selection in the annexes of the standards is based and shows physically meaningful leeway. KW - European standard KW - Laser safety KW - Personal protective equipment PY - 2015 DO - https://doi.org/10.1515/aot-2015-0043 SN - 2192-8576 SN - 2192-8584 VL - 4 IS - 5-6 SP - 389 EP - 395 PB - De Gruyter CY - Berlin; Boston, Mass. AN - OPUS4-35072 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Sekundärstrahlungsemission bei der UKP-Laser-Anwendung: Herausforderung für die Arbeitssicherheit N2 - Im Vortrag werden die Risiken, insbesondere die unerwünschte Erzeugung von Röntgenstrahlung, bei der Nutzung ultrakurzer Laserimpulse in der Materialbearbeitung beschrieben. Neue Anforderungen an den Arbeitsschutz werden dargestellt. T2 - SPECTARIS, Deutscher Industrieverband für optische, medizinische und mechatronische Technologien e.V., Veranstaltung Technische Kommission Photonik CY - Berlin, Germany DA - 27.11.2018 KW - Ultrakurze Laserimpulse KW - Materialbearbeitung KW - Röntgenstrahlung KW - Arbeitsschutz PY - 2018 AN - OPUS4-46859 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Kautek, Wolfgang A1 - Hertwig, Andreas A1 - Martin, Sven A1 - Krüger, Jörg A1 - Lenzner, Matthias A1 - Spielmann, C. A1 - Lenner, M. A1 - Bunte, J. A1 - Puester, T. A1 - Burmester, T. A1 - Fiedler, A. A1 - Heberer, E. A1 - Brose, M. A1 - Stingl, A. A1 - Kiehl, P. A1 - Hönigsmann, H. A1 - Trautinger, F. A1 - Grabner, G. T1 - Safety in Femtosecond Laser Technology - Recent Results of a European Research Project (406) T2 - Conference proceedings & program of the International Laser Safety Conference T2 - International Laser Safety Conference 2003 ; ILSC 2003 CY - Jacksonville, FL, USA DA - 2003-03-10 PY - 2003 SN - 0-912035-38-2 SP - 1(?) EP - 10(?) PB - Laser Institute of America CY - Orlando, Fla. AN - OPUS4-2259 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Röntgenstrahlungsexposition bei der Anwendung von Ultrakurzpulslasern in der Medizin N2 - Die Laserbearbeitung von Materialien mit ultrakurzen Laserpulsen kann zu einer sekundären Emission gefährlicher Röntgenstrahlen führen. Dieser Effekt wurde bisher bei der Bearbeitung von technischen Materialien wie Metallen beobachtet. Die Röntgenemission bei der abtragenden Bearbeitung von biologischen Geweben ist noch weitgehend unerforscht. Der Vortrag präsentiert erste Untersuchungen und Ergebnisse des radiologischen Gefährdungspotentials bei der medizinischen Anwendung von Ultrakurzpulslasern am Menschen. T2 - Bayerische Laserschutztage 2024 CY - Nuremberg, Germany DA - 17.01.2024 KW - Ultrakurzpulslaser KW - Laser-induzierte Röntgenstrahlung KW - Medizinische Anwendung KW - Auge KW - Zahn PY - 2024 AN - OPUS4-59399 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg A1 - Legall, Herbert A1 - Schwanke, Christoph A1 - Bonse, Jörn T1 - Röntgenemission bei der UKP-Laser-Materialbearbeitung N2 - Der Vortrag stellt Untersuchungen im Rahmen eines BMBF-geförderten Vorhabens zur unerwünschten Röntgenemission bei der Materialbearbeitung mit ultrakurzen Laserpulsen vor. T2 - Seminar LEF - Laser in der Elektronikproduktion & Feinwerktechnik CY - Fürth, Germany DA - 26.02.2019 KW - Ultrakurze Laserpulse KW - Materialbearbeitung KW - Sekundärstrahlung KW - Röntgenemission KW - Laserschutz PY - 2019 AN - OPUS4-47468 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Derrien, Thibault A1 - Krüger, Jörg A1 - Itina, T.E. A1 - Höhm, S. A1 - Rosenfeld, A. A1 - Bonse, Jörn T1 - Rippled area formed by surface plasmon polaritons upon femtosecond laser double-pulse irradiation of silicon: the role of carrier generation and relaxation processes JF - Applied physics A N2 - The formation of laser-induced periodic surface structures (LIPSS, ripples) upon irradiation of silicon with multiple irradiation sequences consisting of femtosecond laser pulse pairs (pulse duration 150 fs, central wavelength 800 nm) is studied numerically using a rate equation system along with a two-temperature model accounting for one- and two-photon absorption and subsequent carrier diffusion and Auger recombination processes. The temporal delay between the individual equal-energy fs-laser pulses was varied between 0 and ~4 ps for quantification of the transient carrier densities in the conduction band of the laser-excited silicon. The results of the numerical analysis reveal the importance of carrier generation and relaxation processes in fs-LIPSS formation on silicon and quantitatively explain the two time constants of the delay-dependent decrease of the low spatial frequency LIPSS (LSFL) area observed experimentally. The role of carrier generation, diffusion and recombination is quantified individually. PY - 2014 DO - https://doi.org/10.1007/s00339-013-8205-2 SN - 0947-8396 VL - 117 IS - 1 SP - 77 EP - 81 PB - Springer CY - Berlin AN - OPUS4-31451 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Derrien, Thibault A1 - Krüger, Jörg A1 - Itina, T.E. A1 - Höhm, S. A1 - Rosenfeld, A. A1 - Bonse, Jörn T1 - Rippled area formed by surface plasmon polaritons upon femtosecond laser double-pulse irradiation of silicon JF - Optics express N2 - The formation of near-wavelength laser-induced periodic surface structures (LIPSS) on silicon upon irradiation with sequences of Ti:sapphire femtosecond laser pulse pairs (pulse duration 150 fs, central wavelength 800 nm) is studied theoretically. For this purpose, the nonlinear generation of conduction band electrons in silicon and their relaxation is numerically calculated using a two-temperature model approach including intrapulse changes of optical properties, transport, diffusion and recombination effects. Following the idea that surface plasmon polaritons (SPP) can be excited when the material turns from semiconducting to metallic state, the 'SPP active area' is calculated as function of fluence and double-pulse delay up to several picoseconds and compared to the experimentally observed rippled surface areas. Evidence is presented that multi-photon absorption explains the large increase of the rippled area for temporally overlapping pulses. For longer double-pulse delays, relevant relaxation processes are identified. The results demonstrate that femtosecond LIPSS on silicon are caused by the excitation of SPP and can be controlled by temporal pulse shaping. PY - 2013 DO - https://doi.org/10.1364/OE.21.029643 SN - 1094-4087 VL - 21 IS - 24 SP - 29643 EP - 29655 PB - Optical Society of America CY - Washington, DC AN - OPUS4-29650 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Legall, Herbert A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - Review of x-ray exposure and safety issues arising from ultra-short pulse laser material processing JF - Journal of Radiological Protection N2 - Laser processing with ultra-short laser pulses enables machining of materials with high accuracy and throughput. The development of novel laser Technologies with laser pulse repetition rates up to the MHz range opened the way for industrial manufacturing processes. From a radiological point of view this evolution is important, because x-ray radiation can be generated as an unwanted side effect in laser material processing. Even if the emitted x-ray dose per pulse is comparably low, the x-ray dose can become hazardous to health at high laser repetition rates. Therefore, radiation protection must be considered. This article provides an overview on the generation and detection of x-rays in laser material processing, as well as on the handling of this radiation risk in the framework of radiological protection. KW - Ultra-short pulse laser processing KW - Laser-induced x-ray emission KW - Radiation protection PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-522376 DO - https://doi.org/10.1088/1361-6498/abcb16 VL - 41 IS - 1 SP - R28 EP - R42 AN - OPUS4-52237 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg A1 - Starke, K. A1 - Ristau, D. A1 - Martin, Sven A1 - Hertwig, Andreas A1 - Riede, W. A1 - Theiss, C. A1 - Raab, V. A1 - Sirutkaitis, V. A1 - Rudolph, W. T1 - Results of a round-robin experiment in multiple-pulse LIDT measurment with ultrashort pulses T2 - Boulder Damage Symposium T2 - Boulder Damage Symposium CY - Boulder, CO, USA DA - 2003-09-22 PY - 2003 AN - OPUS4-5016 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Starke, K. A1 - Ristau, D. A1 - Martin, Sven A1 - Hertwig, Andreas A1 - Krüger, Jörg A1 - Allenspacher, P. A1 - Riede, W. A1 - Meister, S. A1 - Theiss, C. A1 - Sabbah, A. A1 - Rudolph, W. A1 - Raab, V. A1 - Grigonis, R. A1 - Rakickas, T. A1 - Sirutkaitis, V. ED - Exarhos, G. J. T1 - Results of a round-robin experiment in multiple-pulse LIDT measurement with ultrashort pulses T2 - Laser-induced damage in optical materials - 2003 T2 - 35th Annual Boulder Damage Symposium ; 35th Annual Symposium on Optical Materials for High-Power Lasers CY - Boulder, CO, USA DA - 2003-09-22 KW - Multiple-pulse damage KW - ISO 11254-2 KW - S on 1-LIDT KW - Round-robin experiment KW - CHOCLAB PY - 2004 SN - 0-8194-5163-0 DO - https://doi.org/10.1117/12.525135 SN - 0038-7355 N1 - Serientitel: Proceedings of SPIE – Series title: Proceedings of SPIE IS - 5273 SP - 388 EP - 395 PB - SPIE, the International Society for Optical Engineering CY - Bellingham, Wash. AN - OPUS4-4948 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Urech, L. A1 - Lippert, T. A1 - Wokaun, A. A1 - Martin, Sven A1 - Mädebach, Heinrich A1 - Krüger, Jörg T1 - Removal of doped poly(methylmetacrylate) from tungsten and titanium substrates by femto- and nanosecond laser cleaning JF - Applied surface science N2 - The influence of different laser pulse lengths on the removal of a polymer layer from metal substrates was investigated. As model systems, doped poly(methylmetacrylate) (PMMA) on titanium and tungsten substrates were selected. The ablation threshold and irradiation spot morphology of titanium and tungsten were compared for femtosecond (fs) and nanosecond (ns) laser irradiation and different pulse numbers. Nanosecond laser treatment resulted in a non-homogeneous surface morphology for both titanium and tungsten substrates. Femtosecond irradiation of tungsten revealed a homogeneous ablation spot with little changes in the surface morphology. For titanium, the formation of columnar structures within the irradiation spot was observed. Two different dopant concentrations were used for PMMA to achieve an equal linear absorption coefficient for the femto- and nanosecond laser wavelengths of 790 and 1064 nm. The best results were achieved for the removal of doped PMMA by femtosecond laser irradiation, where only a minimal modification of the metal surface was detected. In the case of nanosecond laser exposure, a pronounced change of the structure was observed, suggesting that damage-free cleaning of the selected metal may only be possible using femtosecond laser pulses. Different experimental parameters, such as laser fluence, pulse repetition rate and sample speed were also investigated to optimize the cleaning quality of doped PMMA from tungsten substrates with femtosecond laser pulses. KW - Poly(methylmetacrylate) KW - Laser treatment KW - Tungsten KW - Titanium KW - Femtosecond PY - 2006 DO - https://doi.org/10.1016/j.apsusc.2005.07.109 SN - 0169-4332 SN - 1873-5584 VL - 252 IS - 13 SP - 4754 EP - 4758 PB - North-Holland CY - Amsterdam AN - OPUS4-12368 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ringleb, F. A1 - Eylers, K. A1 - Teubner, T. A1 - Boeck, T. A1 - Symietz, Christian A1 - Bonse, Jörn A1 - Andree, Stefan A1 - Krüger, Jörg A1 - Heidmann, B. A1 - Schmid, M. A1 - Lux-Steiner, M. T1 - Regularly arranged indium islands on glass/molybdenum substrates upon femtosecond laser and physical vapor deposition processing JF - Applied Physics Letters N2 - A bottom-up approach is presented for the production of arrays of indium islands on a molybdenum layer on glass, which can serve as micro-sized precursors for indium compounds such as copper-indium-gallium-diselenide used in photovoltaics. Femtosecond laser ablation of glass and a subsequent deposition of a molybdenum film or direct laser processing of the molybdenum film both allow the preferential nucleation and growth of indium islands at the predefined locations in a following indium-based physical vapor deposition (PVD) process. A proper choice of laser and deposition parameters ensures the controlled growth of indium islands exclusively at the laser ablated spots. Based on a statistical analysis, these results are compared to the non-structured molybdenum surface, leading to randomly grown indium islands after PVD. KW - Femtosecond laser KW - Physical vapor deposition KW - Indium KW - Molybdenum substrate KW - Microconcentrator solar cell PY - 2016 DO - https://doi.org/10.1063/1.4943794 SN - 0003-6951 VL - 108 IS - 11 SP - 111904-1 EP - 111904-4 AN - OPUS4-35602 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Florian, Camilo A1 - Kirner, Sabrina V. A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Quo vadis LIPSS? – Applications of laser-induced periodic surface structures T2 - Tagungsband zur 11. Mittweidaer Lasertagung N2 - Laser-induced periodic surface structures (LIPSS, ripples) are a universal phenomenon that can be observed on almost any material after the irradiation by linearly polarized laser beams, particularly when using ultrashort laser pulses with durations in the femtosecond to picosecond range. During the past years significantly increasing industrial and research activities have been reported in the field of LIPSS, since their generation in a single-step process provides a simple way of nanostructuring and surface functionalization towards the control of optical, mechanical or chemical surface properties. In this contribution the mechanisms of formation and current trends and applications of LIPSS are reviewed, including the colorization of technical surfaces, the control of surface wetting properties, the mimicry of the natural texture of animals, the tailoring of surface colonization by bacterial biofilms, the advancement of leadless medical pacemakers, and the improvement of the tribological performance of nanostructured metal surfaces. T2 - 11. Mittweidaer Lasertagung CY - Mittweida, Germany DA - 13.11.2019 KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser ablation KW - Surface functionalization KW - Applications PY - 2019 VL - 3/1 SP - 41 EP - 43 PB - Hochschule Mittweida CY - Mittweida AN - OPUS4-49673 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kautek, Wolfgang A1 - Pentzien, Simone A1 - Conradi, Andrea A1 - Krüger, Jörg A1 - Brzezinka, Klaus-Werner T1 - Pulsed-laser deposition and boron-blending of diamond-like carbon (DLC) thin films JF - Applied surface science KW - Pulslaser KW - Bor KW - Dünnfilmtechnologie KW - Dünnfilm, diamantartig PY - 1996 SN - 0169-4332 SN - 1873-5584 VL - 106 SP - 158 EP - 165 PB - North-Holland CY - Amsterdam AN - OPUS4-630 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - Pulse number dependence of laser-induced periodic surface structures for femtosecond laser irradiation of silicon JF - Journal of applied physics N2 - The formation of nearly wavelength-sized laser-induced periodic surface structures (LIPSS) on single-crystalline silicon upon irradiation with single (N = 1) and multiple (N ≤ 1000) linearly polarized femtosecond (fs) laser pulses (pulse duration τ = 130 fs, central wavelength λ = 800 nm) in air is studied experimentally. Scanning electron microscopy (SEM) and optical microscopy are used for imaging of the ablated surface morphologies, both revealing LIPSS with periodicities close to the laser wavelength and an orientation always perpendicular to the polarization of the fs-laser beam. It is experimentally demonstrated that these LIPSS can be formed in silicon upon irradiation by single fs-laser pulses—a result that is additionally supported by a recent theoretical model. Two-dimensional Fourier transforms of the SEM images allow the detailed analysis of the distribution of the spatial frequencies of the LIPSS and indicate, at a fixed peak fluence, a monotonous decrease in their mean spatial period between ~770 nm (N = 1) and 560 nm (N = 1000). The characteristic decrease in the LIPSS period is caused by a feedback-mechanism acting upon excitation of surface plasmon polaritons at the rough silicon surface which is developing under the action of multiple pulses into a periodically corrugated surface. KW - Elemental semiconductors KW - Fourier transforms KW - Laser beam effects KW - Optical microscopy KW - Polarisation KW - Polaritons KW - Scanning electron microscopy KW - Silicon KW - Surface morphology KW - Surface plasmons PY - 2010 UR - http://jap.aip.org/resource/1/japiau/v108/i3/p034903_s1 DO - https://doi.org/10.1063/1.3456501 SN - 0021-8979 SN - 1089-7550 VL - 108 IS - 3 SP - 034903-1 - 034903-5 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-21804 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Derrien, T. J.-Y. A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Properties of surface plasmon polaritons on lossy materials: lifetimes, periods and excitation conditions JF - Journal of Optics N2 - The possibility to excite surface plasmon polaritons (SPPs) at the interface between two media depends on the optical properties of both media and geometrical aspects. Specific conditions allowing the coupling of light with a plasmon-active interface must be satisfied. Plasmonic effects are well described in noble metals where the imaginary part of the dielectric permittivity is often neglected ('perfect medium approximation (PMA)'). However, some systems exist for which such approximation cannot be applied, hence requiring a refinement of the common SPP theory. In this context, several properties of SPPs such as excitation conditions, period of the electromagnetic field modulation and SPP lifetime then may strongly deviate from that of the PMA. In this paper, calculations taking into account the imaginary part of the dielectric permittivities are presented. The model identifies analytical terms which should not be neglected in the mathematical description of SPPs on lossy materials. These calculations are applied to numerous material combinations resulting in a prediction of the corresponding SPP features. A list of plasmon-active interfaces is provided along with a quantification of the above mentioned SPP properties in the regime where the PMA is not applicable. KW - plasmon lifetime KW - surface plasmon polaritons KW - lossy materials PY - 2016 DO - https://doi.org/10.1088/2040-8978/18/11/115007 SN - 2040-8986 (online) / 2040-8978 (print) VL - 18 IS - 11 SP - 115007 PB - IOP Publishing Ltd AN - OPUS4-37905 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Andree, Stefan A1 - Heidmann, B. A1 - Ringleb, F. A1 - Eylers, K. A1 - Bonse, Jörn A1 - Boeck, T. A1 - Schmid, M. A1 - Krüger, Jörg T1 - Production of precursors for micro-concentrator solar cells by femtosecond laser-induced forward transfer JF - Applied Physics A N2 - Single-pulse femtosecond laser-induced forward transfer (LIFT, 30 fs, 790 nm) is used to deposit micron-sized dots of copper and/or indium onto a molybdenum layer on glass. Such systems can serve as precursors for the bottom-up manufacturing of micro-concentrator solar cells based on copper-indium-gallium-diselenide. The influence of the thickness of the copper, indium and combined copper-indium donor layers on the quality of the transferred dots was qualified by scanning electron microscopy, energy-dispersive X-ray analysis, and optical microscopy. The potential for manufacturing of a spatial arrangement adapted to the geometry of micro-lens arrays needed for micro-concentrator solar cells is demonstrated. T2 - EMRS Spring Meeting 2017, Symposium X “New frontiers in laser interaction: from hard coatings to smart materials" CY - Strasbourg, France DA - 22.05.2017 KW - Laser-induced forward transfer (LIFT) KW - Femtosecond laser KW - Micro-concentrator solar cell KW - Copper-indium-gallium-diselenide KW - CIGSe PY - 2017 DO - https://doi.org/10.1007/s00339-017-1282-x SN - 1432-0630 SN - 0947-8396 VL - 123 SP - Article 670, 1 EP - 8 AN - OPUS4-42273 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Production of micro solar cells using femtosecond laser pulses N2 - A promising technology in photovoltaics is based on micro-concentrator solar cells, where the photovoltaic active area is realized as an array of sub-millimeter sized thin-film solar cells. For copper-indium-gallium-diselenide (CIGSe), the solar cells can be arranged in the foci of a regular arrangement of micro-lenses to enhance their efficiency by light concentration, to allow a better heat dissipation and to save expensive raw material (indium). Different approaches to produce micro-sized precursors of CIGSe absorbers on molybdenum are presented using 30-fs laser pulses at 790 nm wavelength. On the one hand, a multi pulse surface structuring of the molybdenum or the underlying glass substrate and a subsequent physical vapor deposition (PVD) process were used for a site-selective aggregation of indium droplets. On the other hand, a single pulse laser-induced forward transfer (LIFT) was utilized to selectively deposit combined copper/indium/gallium precursor pixels on the molybdenum back contact of the solar cell. It was demonstrated that a postprocessing (selenization, isolation, contacting) of the laser-generated micro-sized precursors results in an array of working CIGSe solar cells with an efficiency of 2.8% for 1 sun illumination. T2 - 15th Erwin Schrödinger Colloquium 2017 CY - Vienna, Austria DA - 01.12.2017 KW - Solar cell KW - Micro-concentrator KW - Copper-indium-gallium-diselenide (CIGSe) KW - Femtosecond laser KW - Laser-induced forward transfer (LIFT) PY - 2017 AN - OPUS4-43338 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 JF - Journal of applied physics 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 - 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 T2 - Femtosecond technology for technical and medical applications 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 - Krüger, Jörg A1 - Kautek, Wolfgang A1 - Lenzner, M. A1 - Krausz, F. T1 - Precision laser ablation of dielectrics in the 10-fs regime JF - Applied physics A N2 - Zusammenfassung Laser pulses in the 10-fs domain provide a quality of micromachining of fused silica and borosilicate glass that is unobtainable with longer pulses in the range of several 100 femtoseconds up to picoseconds. The shortening of the pulses reduces the statistical behavior of the material removal and the ablation process thus attains a more deterministic and reproducible character. The improved reproducibility of ablation is accompanied by significantly smoother morphology. This offers the potential for lateral and vertical machining precision of the order of 100 nm and 10 nm, respectively. KW - Laser ablation PY - 1999 DO - https://doi.org/10.1007/s003390050906 SN - 0947-8396 VL - 68 IS - 3 SP - 369 EP - 371 PB - Springer CY - Berlin AN - OPUS4-825 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Derrien, Thibault A1 - Koter, Robert A1 - Krüger, Jörg A1 - Höhm, S. A1 - Rosenfeld, A. A1 - Bonse, Jörn T1 - Plasmonic formation mechanism of periodic 100-nm-structures upon femtosecond laser irradiation of silicon in water JF - Journal of applied physics N2 - The formation of laser-induced periodic surface structures (LIPSS) upon irradiation of silicon by multiple (N = 100) linearly polarized Ti:sapphire femtosecond laser pulses (duration τ = 30 fs, center wavelength λ0 ~ 790 nm) is studied experimentally in air and water environment. The LIPSS surface morphologies are characterized by scanning electron microscopy and their spatial periods are quantified by two-dimensional Fourier analyses. It is demonstrated that the irradiation environment significantly influences the periodicity of the LIPSS. In air, so-called low-spatial frequency LIPSS (LSFL) were found with periods somewhat smaller than the laser wavelength (ΛLSFL ~ 0.7 × λ0) and an orientation perpendicular to the laser polarization. In contrast, for laser processing in water a reduced ablation threshold and LIPSS with approximately five times smaller periods ΛLIPSS ~ 0.15 × λ0 were observed in the same direction as in air. The results are discussed within the frame of recent LIPSS theories and complemented by a thin film based surface plasmon polariton model, which successfully describes the tremendously reduced LIPSS periods in water. PY - 2014 DO - https://doi.org/10.1063/1.4887808 SN - 0021-8979 SN - 1089-7550 VL - 116 IS - 7 SP - 074902-1 EP - 074902-8 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-31209 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Voss, Heike A1 - Knigge, Xenia A1 - Knapic, D. A1 - Weise, Matthias A1 - Sahre, Mario A1 - Hertwig, Andreas A1 - Sacco, A. A1 - Rossi, A. M. A1 - Radnik, Jörg A1 - Müller, Kai A1 - Wasmuth, Karsten A1 - Krüger, Jörg A1 - Hassel, A. W. A1 - Hodoroaba, Vasile-Dan A1 - Bonse, Jörn T1 - Picosecond laser processing of hierarchical micro–nanostructures on titanium alloy upon pre- and postanodization: morphological, structural, and chemical effects JF - Physica Status Solidi A N2 - Recent publications indicate that the order of electrochemical anodization (before or after the laser processing step) plays an important role for the response of bone-forming osteoblasts—an effect that can be utilized for improving permanent dental or removable bone implants. For exploring these different surface functionalities, multimethod morphological, structural, and chemical characterizations are performed in combination with electrochemical pre- and postanodization for two different characteristic microspikes covered by nanometric laser-induced periodic surface structures on Ti–6Al–4V upon irradiation with near-infrared ps-laser pulses (1030 nm wavelength, ≈1 ps pulse duration, 67 and 80 kHz pulse repetition frequency) at two distinct sets of laser fluence and beam scanning parameters. This work involves morphological and topographical investigations by scanning electron microscopy and white light interference microscopy, structural material examinations via X-ray diffraction, and micro-Raman spectroscopy, as well as near-surface chemical analyses by X-ray photoelectron spectroscopy and hard X-ray photoelectron spectroscopy. The results allow to qualify the mean laser ablation depth, assess the spike geometry and surface roughness parameters, and provide new detailed insights into the near-surface oxidation that may affect the different cell growth behavior for pre- or postanodized medical implants. T2 - 2023 E-MRS Spring Meeting, Symposium L "Making light matter: lasers in material sciences and photonics" CY - Strasbourg, France DA - 29.05.2023 KW - Hierarchical micro-nanostructures KW - Laser-induced periodic surface structures (LIPSS) KW - Ultrashort laser pulses KW - Ti-6Al-4V alloy KW - X-ray photoelectron spectroscopy PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-601962 DO - https://doi.org/10.1002/pssa.202300920 SN - 1862-6319 SP - 1 EP - 11 PB - Wiley-VCH GmbH CY - Weinheim AN - OPUS4-60196 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kautek, Wolfgang A1 - Rudolph, Pascale A1 - Daminelli-Widany, Grazia A1 - Krüger, Jörg T1 - Physico-chemical aspects of femtosecond-pulse-laser-induced surface nanostructures JF - Applied physics A N2 - Near-ablation threshold investigations focusing on the generation of periodic nanostructures and their correlation with physico-chemical properties of the solid phase such as e.g., the material-dependent surface energy, were conducted. Molecular dynamic modelling in the sub-picosecond time domain was used to consider ultrafast opto-electronic processes triggering surface reorganization reactions. Fluid containment of solid interfaces showed strong influence on the resulting micro- and nanostructures due to its drastic reduction of the surface energy. The phenomena are discussed in respect to the minimization of the surface free energy in dependence of material composition and interfacial structure. PY - 2005 DO - https://doi.org/10.1007/s00339-005-3211-7 SN - 0947-8396 VL - 81 SP - 65 EP - 70 PB - Springer CY - Berlin AN - OPUS4-7403 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Niino, Hiroyuki A1 - Krüger, Jörg A1 - Kautek, Wolfgang ED - Dubowski, J. ED - Dyer, P. T1 - Photochemical surface modification of polyurethane films with biomaterial by excimer laser processing T2 - Laser applications in microelectronic and optoelectronic manufacturing III T2 - 3rd Three-Day Conference on Laser Applications in Microelectronic and Optoelectronic Manufacturing, LAMOM ; LASE ; Photonics West CY - San José, CA, USA DA - 1998-01-26 KW - Laser irradiation surface effects KW - Surface and interface chemistry of polymers KW - Photochemical reactions of biomolecules KW - Biochemical reaction mechanisms and kinetics PY - 1998 SN - 0-8194-2713-6 SN - 1605-7422 N1 - Serientitel: SPIE proceedings series – Series title: SPIE proceedings series IS - 3274 SP - 128 EP - 132 PB - SPIE CY - Bellingham, Wash. AN - OPUS4-12040 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Jörg A1 - Kautek, Wolfgang A1 - Lenzner, M. A1 - Krausz, F. T1 - Photoablation with sub-10 fs laser pulses JF - Applied surface science N2 - Ablation experiments in several glasses with single and multishot irradiation by laser pulses in the 10-fs pulse duration domain are presented; physical and technological implications are discussed. We demonstrate that these short pulses offer the potential for lateral and vertical machining precision of the order of 100 nm. KW - Ablation KW - Laser pulses KW - Femtosecond pulses PY - 2000 DO - https://doi.org/10.1016/S0169-4332(99)00432-8 SN - 0169-4332 SN - 1873-5584 VL - 154-155 SP - 11 EP - 16 PB - North-Holland CY - Amsterdam AN - OPUS4-800 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Kautek, Wolfgang A1 - Sorg, N. A1 - Krüger, Jörg ED - Brieger, M. T1 - Optical second-harmonic generation (SHG) on semiconductor electrodes by means of femtosecond and nanosecond-pulse lasers T2 - Semiconductor processing and characterization with lasers N2 - In situ optical second-harmonic generation (SHG) on centrosymmetric crystalline semiconductor electrodes opens up a new field of in situ investigations of hurried solid state interfaces and metal front contacts relevant to electronic and photovoltaic devices, which are rarely accessible by other methods. Photoelectrochemical nanosecond- and femtosecond-pulse laser investigations of silicon (111) electrodes show that in situ SHG is feasible in such complex interfacial systems. In a p-p polarization configuration, the azimuthal dependence of the SHG from oxide-covered and bare n-Si (111) electrodes, with and without Ni contact deposits, have been studied. Etching and regrowth of silicon oxides as well as burried interfacial electric field distributions were monitored. In situ SHG is shown to be extremely sensitive to trapped interfacial charge, crystal misorientations and surface step arrays. An advantage of femtosecond-pulses is the fact that illumination fluences that are well below the damage threshold, but still with sufficient power density, can be applied. (Author) T2 - 1st International Symposium on Semiconductor Processing and Characterization with Lasers - Applications in Photovoltaics CY - Stuttgart, Germany DA - 1994-04-18 KW - Femtosecond-Pulse Laser KW - Sub-Picosecond-Pulse Laser KW - Semiconductors KW - Silicon KW - Second-Harmonic Generation KW - SHG KW - Nonlinear Electroreflectance KW - Etch Process KW - Oxide KW - Interfacial Electronic States KW - Fermi-Level Pinning KW - MOS Diode PY - 1995 SN - 0-87849-683-1 DO - https://doi.org/10.4028/www.scientific.net/MSF.173-174.285 SN - 0255-5476 N1 - Serientitel: Materials science forum – Series title: Materials science forum IS - 173/174 SP - 285 EP - 290 PB - Trans Tech Publ. CY - Aedermannsdorf AN - OPUS4-11672 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Lenzner, M. A1 - Sartania, S. A1 - Spielmann, C. A1 - Krausz, F. A1 - Krüger, Jörg A1 - Kautek, Wolfgang T1 - Optical Damage of Dielectrics down to 5 fs T2 - Summaries of papers presented at the Conference on Lasers and Electro-Optics (OSA technical digest series 1997,11) T2 - 17th Conference on Lasers and Electro-Optics (CLEO) CY - Baltimore, MD, USA DA - 1997-05-18 PY - 1997 SN - 1-557-52498-X IS - 11 SP - 218 EP - 219 PB - Optical Society of America CY - Washington, DC AN - OPUS4-12043 LA - eng 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 JF - Journal of applied physics 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 - JOUR A1 - Mero, M. A1 - Clapp, B. A1 - Jasapara, J.C. A1 - Rudolph, W. A1 - Ristau, D. A1 - Starke, K. A1 - Krüger, Jörg A1 - Martin, Sven A1 - Kautek, Wolfgang T1 - On the damage behavior of dielectric films when illuminated with multiple femtosecond laser pulses JF - Optical engineering N2 - The physical effects reducing the damage threshold of dielectric films when exposed to multiple femtosecond pulses are investigated. The measured temperature increase of a Ta2O5 film scales exponentially with the pulse fluence. A polarized luminescence signal is observed that depends quadratically on the pulse fluence and is attributed to twophoton excitation of self-trapped excitons that form after band-to-band excitation. The damage fluence decreases with increasing pulse number, but is independent of the repetition rate from 1 Hz to 1 kHz at a constant pulse number. The repetition rate dependence of the breakdown threshold is also measured for TiO2 , HfO2, Al2O3, and SiO2 films. A theoretical model is presented that explains these findings. KW - Laser-induced damage KW - Laser materials KW - Ultrafast phenomena KW - Coatings PY - 2005 DO - https://doi.org/10.1117/1.1905343 SN - 0892-354X VL - 44 IS - 5 SP - 051107-1-051107-7 PB - Dekker CY - New York, NY AN - OPUS4-7406 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 JF - Journal of cultural heritage 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 - 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 - Optics and lasers in biomedicine and culture 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 - CONF A1 - Krüger, Jörg A1 - Mann, Guido A1 - Vogel, Jens A1 - Preuß, Rüdiger A1 - Vaziri, Pouya A1 - Eberstein, Markus A1 - Zoheidi, M. T1 - Nanosecond laser-induced surface damage of preforms and optical multimode fibers T2 - COLA 2007, Conference on Laser Ablation, Guia de Isora T2 - COLA 2007, Conference on Laser Ablation, Guia de Isora CY - Tenerife, Spain DA - 2007-09-24 PY - 2007 AN - OPUS4-14956 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mann, Guido A1 - Vogel, Jens A1 - Preuß, Rüdiger A1 - Vaziri, Pouya A1 - Zoheidi, M. A1 - Eberstein, Markus A1 - Krüger, Jörg T1 - Nanosecond laser-induced surface damage of optical multimode fibers and their preforms JF - Applied physics A N2 - High-power optical multimode fibers are essential components for materials processing and surgery and can limit the performance of expensive systems due to breakdown at the end faces. The aim of this paper is the determination of laser-induced damage thresholds (LIDT) of fibers (FiberTech) and preforms (Heraeus Suprasil F300). Preforms served as models. They were heated up to maximum temperatures of 1100, 1300 and 1500°C and cooled down to room temperature at rates of 10 K min-1 (oven) and ~105 K min-1 (quenched in air) to freeze in various structural states simulating different conditions similar to a drawing process during the production of fibers. 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 used. For the preforms, LIDT values (1-on-1) ranged from 220 to 350 J/cm² (1064 nm) and from 80 to 110 J/cm² (532 nm), respectively. A multi-pulse impact changed the thresholds to lower values. The LIDT (1064 nm wavelength) of the preforms can be regarded as a lower limit for those of the fibers. PY - 2008 DO - https://doi.org/10.1007/s00339-008-4576-1 SN - 0947-8396 VL - 92 IS - 4 SP - 853 EP - 857 PB - Springer CY - Berlin AN - OPUS4-17779 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg A1 - Mann, Guido A1 - Vogel, Jens A1 - Preuß, Rüdiger A1 - Vaziri, Pouya A1 - Eberstein, Markus A1 - Zoheidi, M. T1 - Nanosecond laser damage resistance of optical multimode fibers prepared differently T2 - EMRS 2007 Spring Meeting, Symposium P: Laser synthesis and processing of advanced materials T2 - EMRS 2007 Spring Meeting, Symposium P: Laser synthesis and processing of advanced materials CY - Strasbourg, France DA - 2007-05-28 PY - 2007 AN - OPUS4-14762 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mann, Guido A1 - Vogel, Jens A1 - Preuß, Rüdiger A1 - Vaziri, Pouya A1 - Zoheidi, M. A1 - Eberstein, Markus A1 - Krüger, Jörg T1 - Nanosecond laser damage resistance of differently prepared semi-finished parts of optical multimode fibers JF - Applied surface science N2 - Optical multimode fibers are applied in materials processing (e.g. automotive industry), defense, aviation technology, medicine and biotechnology. One challenging task concerning the production of multimode fibers is the enhancement of laser-induced damage thresholds. A higher damage threshold enables a higher transmitted average power at a given fiber diameter or the same power inside a thinner fiber to obtain smaller focus spots. In principle, different material parameters affect the damage threshold. Besides the quality of the preform bulk material itself, the drawing process during the production of the fiber and the preparation of the fiber end surfaces influence the resistance. Therefore, the change of the laser-induced damage threshold of preform materials was investigated in dependence on a varying thermal treatment and preparation procedure. Single and multi-pulse laser-induced damage thresholds of preforms (F300, Heraeus) were measured using a Q-switched Nd:YAG laser at 1064 nm wavelength emitting pulses with a duration of 15 ns, a pulse energy of 12 mJ and a repetition rate of 10 Hz. The temporal and spatial shape of the laser pulses were controlled accurately. Laser-induced damage thresholds in a range from 150 J cm-2 to 350 J cm-2 were determined depending on the number of pulses applied to the same spot, the thermal history and the polishing quality of the samples, respectively. KW - Laser ablation KW - Optical fibers KW - Physical radiation damage KW - Radiation treatment KW - Glass transitions KW - Glasses PY - 2007 DO - https://doi.org/10.1016/j.apsusc.2007.09.032 SN - 0169-4332 SN - 1873-5584 VL - 254 IS - 4 SP - 1096 EP - 1100 PB - North-Holland CY - Amsterdam AN - OPUS4-16207 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mann, Guido A1 - Krüger, Jörg ED - Jitsuno, T. ED - Shao, J. ED - Rudolph, W. T1 - Nanosecond laser damage of optical multimode fibers T2 - Proceedings of SPIE N2 - For pulse laser materials processing often optical step index and gradient index multimode fibers with core diameters ranging from 100 to 600 μm are used. The design of a high power fiber transmission system must take into account limitations resulting from both surface and volume damage effects. Especially, breakdown at the fiber end faces and self-focusing in the fiber volume critically influence the fiber performance. At least operation charts are desirable to select the appropriate fiber type for given laser parameters. In industry-relevant studies the influence of fiber core diameter and end face preparation on laser-induced (surface) damage thresholds (LIDT) was investigated for frequently used all-silica fiber types (manufacturer LEONI). Experiments on preform material (initial fiber material) and compact specimens (models of the cladding and coating material) accompanied the tests performed in accordance with the relevant LIDT standards ISO 21254-1 and ISO 21254 2 for 1-on-1 and S-on-1 irradiation conditions, respectively. The relation beam diameter vs. LIDT was investigated for fused silica fibers. Additionally, laser-induced (bulk) damage thresholds of fused silica preform material F300 (manufacturer Heraeus) in dependence on external mechanical stress simulating fiber bending were measured. All experiments were performed with 10-ns laser pulses at 1064 and 532 nm wavelength with a Gaussian beam profile. T2 - Pacific Rim Laser Damage 2016 CY - Yokohama, Japan DA - 18.05.2016 KW - laser damage KW - optical fiber KW - nanosecond laser KW - fused silica PY - 2016 DO - https://doi.org/10.1117/12.2238515 VL - 9983 SP - 99830T AN - OPUS4-37140 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg A1 - Mann, Guido T1 - Nanosecond laser damage of optical multimode fibers N2 - For pulse laser materials processing often optical step index and gradient index multimode fibers with core diameters ranging from 100 to 600 μm are used. The design of a high power fiber transmission system must take into account limitations resulting from both surface and volume damage effects. Especially, breakdown at the fiber end faces and self-focusing in the fiber volume critically influence the fiber performance. At least operation charts are desirable to select the appropriate fiber type for given laser parameters. In industry-relevant studies the influence of fiber core diameter and end face preparation on laser-induced (surface) damage thresholds (LIDT) was investigated for frequently used all-silica fiber types (manufacturer LEONI). Experiments on preform material (initial fiber material) and compact specimens (models of the cladding and coating material) accompanied the tests performed in accordance with the relevant LIDT standards ISO 11254-1 and ISO 11254-2 for 1-on-1 and S-on-1 illumination conditions, respectively. The relation beam diameter vs. LIDT was investigated for fused silica fibers and preforms. Additionally, the laser-induced (bulk) damage threshold of fused silica preform material F300 (manufacturer Heraeus) in dependence on external mechanical stress simulating fiber bending was measured. All experiments were performed with 10-ns laser pulses at 1064 and 532 nm wavelength with a Gaussian beam profile. T2 - Pacific Rim Laser Damage Conference CY - Yokohama, Japan DA - 18.05.2016 KW - Laser induced damage KW - Optical multimode fiber KW - Nd:YAG laser KW - Nanosecond Pulses PY - 2016 AN - OPUS4-36258 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kirner, Sabrina A1 - Wirth, Thomas A1 - Sturm, Heinz A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Nanometer-resolved chemical analyses of femtosecond laser-induced periodic surface structures on titanium JF - Journal of Applied Physics N2 - The chemical characteristics of two different types of laser-induced periodic surface structures (LIPSS), so-called high and low spatial frequency LIPSS (HSFL and LSFL), formed upon irradiation of titanium surfaces by multiple femtosecond laser pulses in air (30 fs, 790 nm, 1 kHz), are analyzed by various optical and electron beam based surface analytical techniques, including micro-Raman spectroscopy, energy dispersive X-ray analysis, X-ray photoelectron spectroscopy, and Auger electron spectroscopy. The latter method was employed in a high-resolution mode being capable of spatially resolving even the smallest HSFL structures featuring spatial periods below 100 nm. In combination with an ion sputtering technique, depths-resolved chemical information of superficial oxidation processes was obtained, revealing characteristic differences between the two different types of LIPSS. Our results indicate that a few tens of nanometer shallow HSFL are formed on top of a ∼150 nm thick graded superficial oxide layer without sharp interfaces, consisting of amorphous TiO2 and partially crystallized Ti2O3. The larger LSFL structures with periods close to the irradiation wavelength originate from the laser-interaction with metallic titanium. They are covered by a ∼200 nm thick amorphous oxide layer, which consists mainly of TiO2 (at the surface) and other titanium oxide species of lower oxidation states underneath. KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser KW - Oxidation KW - Titanium KW - Auger electron spectroscopy PY - 2017 DO - https://doi.org/10.1063/1.4993128 SN - 0021-8979 VL - 122 IS - 10 SP - 104901, 1 EP - 9 PB - AIP Publishing CY - Melville, NY, USA AN - OPUS4-41905 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Lenzner, M. A1 - Sartania, S. A1 - Spielmann, C. A1 - Krausz, F. A1 - Krüger, Jörg A1 - Kautek, Wolfgang T1 - Nanometer precision material ablation and optical breakdown with sub-10 fs pulses T2 - Ultrafast phenomena XI T2 - 11th International Conference on Ultrafast Phenomena CY - Garmisch-Partenkirchen, Germany DA - 1998-07-12 PY - 1998 SN - 3-540-65430-5 SN - 0172-6218 N1 - Serientitel: Springer Series in chemical physics – Series title: Springer Series in chemical physics IS - 63 SP - 313 EP - 315 PB - Springer CY - Heidelberg AN - OPUS4-12042 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -