TY - JOUR A1 - Epperlein, Nadja A1 - Menzel, Friederike A1 - Schwibbert, Karin A1 - Koter, Robert A1 - Bonse, Jörn A1 - Sameith, Janin A1 - Krüger, Jörg A1 - Toepel, Jörg T1 - Influence of femtosecond laser produced nanostructures on biofilm growth on steel JF - Applied Surface Science N2 - Biofilm formation poses high risks in multiple industrial and medical settings. However, the robust nature of biofilms makes them also attractive for industrial applications where cell biocatalysts are increasingly in use. Since tailoring material properties that affect bacterial growth or its inhibition is gaining attention, here we focus on the effects of femtosecond laser produced nanostructures on bacterial adhesion. Large area periodic surface structures were generated on steel surfaces using 30-fs laser pulses at 790 nm wavelength. Two types of steel exhibiting a different corrosion resistance were used, i.e., a plain structural steel (corrodible) and a stainless steel (resistant to corrosion). Homogeneous fields of laser-induced periodic surface structures (LIPSS) were realized utilizing laser fluences close to the ablation threshold while scanning the sample under the focused laser beam in a multi-pulse regime. The nanostructures were characterized with optical and scanning electron microscopy. For each type of steel, more than ten identical samples were laser-processed. Subsequently, the samples were subjected to microbial adhesion tests. Bacteria of different shape and adhesion behavior (Escherichia coli and Staphylococcus aureus) were exposed to laser structures and to polished reference surfaces. Our results indicate that E. coli preferentially avoids adhesion to the LIPSS-covered areas, whereas S. aureus favors these areas for colonization. KW - Laser-induced periodic surface structures KW - Femtosecond laser KW - Steel KW - Biofilms KW - Microbial adhesion tests PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S0169433217305470 DO - https://doi.org/10.1016/j.apsusc.2017.02.174 SN - 0169-4332 SN - 1873-5584 VL - 418 IS - Part B SP - 420 EP - 424 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-40565 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, Kai A1 - Mirabella, Francesca A1 - Knigge, Xenia A1 - Mezera, Marek A1 - Weise, Matthias A1 - Sahre, Mario A1 - Wasmuth, Karsten A1 - Voss, Heike A1 - Hertwig, Andreas A1 - Krüger, Jörg A1 - Radnik, Jörg A1 - Hodoroaba, Vasile-Dan A1 - Bonse, Jörn T1 - Chemical and topographical changes upon sub-100-nm laser-induced periodic surface structure formation on titanium alloy: the influence of laser pulse repetition rate and number of over-scans JF - Physica Status Solidi A N2 - Titanium and its alloys are known to allow the straightforward laser-based manufacturing of ordered surface nanostructures, so-called high spatial frequency laser-induced periodic surface structures (HSFL). These structures exhibit sub-100 nm spatial periods – far below the optical diffraction limit. The resulting surface functionalities are usually enabled by both, topographic and chemical alterations of the nanostructured surfaces. For exploring these effects, multi-method characterizations were performed here for HSFL processed on Ti–6Al–4V alloy upon irradiation with near-infrared ps-laser pulses (1030 nm, ≈1 ps pulse duration, 1–400 kHz) under different laser scan processing conditions, i.e., by systematically varying the pulse repetition frequency and the number of laser irradiation passes. The sample characterization involved morphological and topographical investigations by scanning electron microscopy (SEM), atomic force microscopy (AFM), tactile stylus profilometry, as well as near-surface chemical analyses hard X-ray photoelectron spectroscopy (HAXPES) and depth-profiling time-of-flight secondary ion mass spectrometry (ToF-SIMS). This provides a quantification of the laser ablation depth, the geometrical HSFL characteristics and enables new insights into the depth extent and the nature of the non-ablative laser-induced near-surface oxidation accompanying these nanostructures. This allows to answer the questions how the processing of HSFL can be industrially scaled up, and whether the latter is limited by heat-accumulation effects. 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 - Laser-induced periodic surface structures (LIPSS) KW - Ultrashort laser pulses KW - Laser processing KW - Hard X-ray photoelectron spectroscopy (HAXPES) KW - Time-of-flight secondary ion mass spectrometry (ToF-SIMS) PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-589902 UR - https://onlinelibrary.wiley.com/doi/full/10.1002/pssa.202300719 DO - https://doi.org/10.1002/pssa.202300719 SN - 1862-6319 VL - 220 SP - 1 EP - 12 PB - Wiley-VCH GmbH CY - Weinheim AN - OPUS4-58990 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 - GEN A1 - Krüger, Jörg A1 - Kautek, Wolfgang ED - Dubowski, J. T1 - Femtosecond-pulse laser processing of metallic and semiconducting thin films T2 - Laser-induced thin film processing KW - Femtosekundenpulslaser KW - Pulslaser KW - Dünnschicht, metallisch KW - Dünnschicht, halbleitend KW - Ablation PY - 1995 SN - 0-8194-1750-5 SN - 1605-7422 N1 - Serientitel: SPIE proceedings series – Series title: SPIE proceedings series IS - 2403 SP - 436 EP - 447 PB - SPIE CY - Bellingham, Wash. AN - OPUS4-637 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Bonse, Jörn A1 - Baudach, Steffen A1 - Krüger, Jörg A1 - Kautek, Wolfgang ED - Phipps, C. T1 - Femtosecond laser micromachining of technical materials T2 - High-power laser ablation III N2 - Micromachining experiments were performed with Ti:sapphire laser pulses (130 fs - 150 fs, 800 nm, approximately 10 Hz) in air. Employing the direct focusing technique, highly absorbing titanium nitride (TiN) and weakly absorbing polyimide (PI) and polymethylmethacrylate (PMMA) served as target materials. The lateral and vertical precision of the laser ablation and morphological features were characterized by scanning force (SFM), scanning electron (SEM) and optical microscopy. For TiN, incubation can be observed, i.e. the single-pulse surface damage threshold (0.26 J/cm2) is by a factor of two greater than the threshold for 100 pulses. Ablation rates below 10 nm per pulse can be achieved. The evolution of sub-wavelength ripples is presented in dependence on pulse number and laser fluence, respectively. The incubation behavior of the polymers can be described by an accumulation model as for TiN. Experiments on PI with varying focal lengths result in the same modification thresholds. Different polarization states of light (linear, circular) lead to a variation of the ablation rate and to various morphological patterns in the ablation craters (wavelength ripples, cones). Swelling of PMMA occurred at fluences below the ablation threshold. T2 - 3rd SPIE's International Conference on High-Power Laser Ablation CY - Santa Fe, NM, USA DA - 24.04.2000 KW - Ablation KW - Femtosecond pulse laser KW - Laser processing KW - Micromachining KW - Polymer KW - Titanium nitride KW - Ripples PY - 2000 SN - 0-8194-3700-X DO - https://doi.org/10.1117/12.407346 SN - 1605-7422 N1 - Serientitel: SPIE proceedings series – Series title: SPIE proceedings series IS - 4065 SP - 161 EP - 172 PB - SPIE CY - Bellingham, Wash. AN - OPUS4-967 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Jörg A1 - Kautek, Wolfgang A1 - Niino, H. T1 - Biomaterial immobilization on polyurethane films by XeCl excimer laser processing JF - Applied physics A N2 - Zusammenfassung The surface chemical modification of polyurethane (PU) films was performed by an UV laser-induced chemical reaction in a polysaccharide solution. This process may be applicable as hydrophilic packaging of implantable medical devices and in vivo sensors. When a PU film in contact with an aqueous alginic acid (AAC) solution was irradiated with a XeCl laser, the PU film turned hydrophilic. Contact angles of water on the film were reduced from 110° to 60°. Since light absorption of the AAC solution at 308 nm was negligibly small, reactive sites were generated solely on the PU surface. There, AAC could be immobilized by chemical bonds thus allowing for a nanometer-scaled grafting of this biomolecule. The mechanism was investigated by surface analyses with Fourier-transform infrared spectroscopy (FT-IR), dye staining, ultraviolet-visible (UV-VIS) spectroscopy, and scanning electron microscopy (SEM) techniques. A one-photon photochemical process could beidentified. PY - 2001 DO - https://doi.org/10.1007/s003390000617 SN - 0947-8396 VL - 72 IS - 1 SP - 53 EP - 57 PB - Springer CY - Berlin AN - OPUS4-926 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Bonse, Jörn A1 - Krüger, Jörg A1 - Kautek, Wolfgang A1 - Wrobel, J. M. T1 - Femtosecond pulse laser machining of InP wafers T2 - Laser applications in microelectronic and optoelectronic manufacturing V N2 - Ablation of indium phosphide wafers in air was performed with 130 fs laser pulses at a wavelength of 800 nm at a low repetition rate of 10 Hz. In order to evaluate the role of the incubation effects, the relationship between the number of laser pulses used for the ablation and the threshold fluence was studied. Particular attention was paid to the chemical composition, surface morphology and structural variations of the ablated area. T2 - 5th Laser Applications in Microelectronics and Optoelectronics Manufacturing Conference (LAMOM) CY - San José, CA, USA DA - 240.01.2000 KW - Femtosecond laser ablation KW - Indium phosphide KW - Auger electron spectroscopy PY - 2000 SN - 0-8194-3550-3 SN - 1605-7422 N1 - Serientitel: SPIE proceedings series – Series title: SPIE proceedings series IS - 3933 SP - 280 EP - 287 PB - SPIE CY - Bellingham, Wash. AN - OPUS4-937 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Krüger, Jörg A1 - Bonse, Jörn A1 - Baudach, Steffen A1 - Kautek, Wolfgang A1 - Lenzner, M. A1 - Wrobel, J. M. T1 - Femtosecond-Pulse Laser Machining of Semiconducting Materials T2 - Conference digest N2 - Summary form only given. Machining investigations of crystalline silicon have been performed with laser pulses at a wavelength of 780 nm in the range between 5 fs and 400 fs. Applying 100 pulses per spot, surface damage thresholds were determined by the measurement of the damage diameter. In this pulse duration regime, the threshold fluences were nearly constant. Single-pulse investigations with 5 fs pulses yielded a value of about 0.15 J cm-2 identical to the multi-pulse experiment. This is in contradiction to the behaviour of dielectrics where incubation effects alter the optical properties down to the 5 fs pulse regime. Employing laser pulses with a duration of 130 fs at a wavelength of 800 nm, single-pulse ablation thresholds of 0.23 J cm-2 and 0.16 J cm-2 were determined for Si and InP in air, respectively. The threshold fluence was calculated from the linear relation between the square of the diameters versus the logarithm of the laser fluences. T2 - CLEO/Europe 2000 ; Conference on Lasers and Electro-Optics Europe ; Conférence Européenne sur les Lasers et l'Electro-Optique ; CLEO/Europe-IQEC CY - Nice, France DA - 2000-09-10 PY - 2000 SN - 0-7803-6319-1 DO - https://doi.org/10.1109/CLEOE.2000.910410 PB - IEEE Service Center CY - Piscataway, NJ AN - OPUS4-958 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kautek, Wolfgang A1 - Martin, Sven A1 - Krüger, Jörg A1 - Lenzner, Matthias A1 - Fiedler, A. ED - Meunier, M. T1 - Femtosecond laser multi-pulse interaction with optical filters and fabrics T2 - Physics and chemistry of advanced laser materials processing N2 - Optical filters and fabrics are important parts of laser safety equipment such as goggles and curtains. A choice of these materials with varying absorption spectra is investigated with respect to their resistance to Ti:sapphire femtosecond laser radiation (800 nm wavelength, 1 kHz repetition rate). Pulse durations down to 30 fs and multiple-pulse irradiation conditions are employed to evaluate technically relevant damage thresholds. The ablation threshold fluences of the absorbing filters are comparable to those observed for transparent materials with 30-fs-pulses. These investigations together with scanning electron microscopy of the surface morphology after laser treatment provide insight into the interaction mechanism of the short pulses with the materials. 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 - OPUS4-1730 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 - CONF A1 - Weidner, Steffen A1 - Falkenhagen, Jana A1 - Friedrich, Jörg Florian A1 - Krüger, Ralph-Peter A1 - Schulz, Günter A1 - Much, Helmut T1 - Liquid Adsorption Chromatography near Critical Conditions of Adsorption coupled with Matrix-assisted Laser/Ionization Mass Spectrometry T2 - Proceedings of the 47th ASMS Conference on Mass Spectrometry and Allied Topics T2 - 47th ASMS Conference on Mass Spectrometry and Allied Topics CY - Dallas, TX, USA DA - 1999-06-13 PY - 1999 CY - Dallas, Tex AN - OPUS4-2165 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Falkenhagen, Jana A1 - Friedrich, Jörg Florian A1 - Schulz, Günter A1 - Krüger, Ralph-Peter A1 - Much, Helmut A1 - Weidner, Steffen T1 - Liquid Adsorption Chromatography near Critical Conditions of Adsorption coupled with Matrix-assisted Laser Desorption/Ionization Mass Spectrometry JF - International journal of polymer analysis and characterization N2 - Chemical heterogeneities and molecular weight distributions of poly(ethylene oxide) (PEO)-co-polymethylene (PM) model oligomers, which are relevant to the synthesis of commonly used tensides, were investigated. For analytical characterization, the well-known principle of liquid adsorption chromatography at 'critical conditions' (LACCC) was modified. Near the critical conditions of adsorption of the PEO unit, e.g., at slight adsorption conditions of PM, the copolymers could be separated according to their PM chain length. The eluates were separated and single fractions of each peak were continuously transferred onto the MALDI target by means of a commercially available device. Simultaneously, the MALDI matrix solution was continuously added with a second pump. This procedure offers the possibility of the formation of homogeneous matrix-polymer textures. By MALDI-MS a complete characterization of the chemical composition (PEO and PM chain length) of each peak could be achieved. The obtained MALDI mass spectra of the eluates at different retention times could be used for the molecular weight calibration of the LAC system. In this way, an additional application of SEC, as in conventional 2D-chromatography, was avoided by using the MALDI method as quasi chromatographic separation KW - Liquid adsorption chromatography KW - Matrix-assisted laser desorption KW - Ionization mass spectrometry KW - Coupling methods KW - MALDI PY - 2000 DO - https://doi.org/10.1080/10236660008034644 SN - 1023-666X SN - 1563-5341 VL - 5 SP - 549 EP - 562 PB - Gordon and Breach Publ. CY - Amsterdam AN - OPUS4-2168 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weidner, Steffen A1 - Falkenhagen, Jana A1 - Much, Helmut A1 - Krüger, Ralph-Peter A1 - Friedrich, Jörg Florian T1 - Determination of chemical and molecular-weight distributions of heterogeneous polymers by means of MALDI-MS coupled with chromatography JF - Polymer preprints T2 - 219th ACS national meeting CY - San Francisco, CA, USA DA - 2000-03-26 PY - 2000 SN - 0032-3934 VL - 41 IS - 1 SP - 655 EP - 656 PB - American Chemical Society CY - Newark, NJ AN - OPUS4-2169 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Rudolph, Pascale A1 - Krüger, Jörg A1 - Baudach, Steffen A1 - Kautek, Wolfgang T1 - Femtosecond pulse laser processing of TiN on silicon JF - Applied surface science N2 - Ultrashort pulse laser microstructuring (pulse duration 130 fs, wavelength 800 nm, repetition rate 2 Hz) of titanium nitride (TiN) films on silicon substrates was performed in air using the direct focusing technique. The lateral and vertical precision of laser ablation was evaluated. The TiN ablation threshold changed with the number of pulses applied to the surface due to an incubation effect. An ablation depth per pulse below the penetration depth of light was observed. Columnar structures were formed in the silicon substrate after drilling through the TiN layer. KW - Femtosecond laser ablation KW - Titanium nitride KW - Silicon KW - Optical properties PY - 2000 DO - https://doi.org/10.1016/S0169-4332(99)00481-X SN - 0169-4332 SN - 1873-5584 VL - 154-155 SP - 659 EP - 663 PB - North-Holland CY - Amsterdam AN - OPUS4-802 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 - JOUR A1 - Krüger, Jörg A1 - Kautek, Wolfgang A1 - Lenzner, M. A1 - Sartania, S. A1 - Spielmann, Ch. A1 - Krausz, F. T1 - Laser micromachining of barium aluminium borosilicate glass with pulse durations between 20 fs and 3 ps JF - Applied surface science KW - Laser micromachining KW - Subpicosecond laser ablation KW - Barium aluminium borosilicate glass PY - 1998 SN - 0169-4332 SN - 1873-5584 IS - 127-129 SP - 892 EP - 898 PB - North-Holland CY - Amsterdam AN - OPUS4-887 LA - eng 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 - 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 - Krüger, Jörg A1 - Kautek, Wolfgang A1 - Krivenko, A.G. A1 - Benderskii, V.A. T1 - Gigantic Hydrogen-Ion Discharge Currents Initiated by a Subpicosecond Laser JF - Russian journal of electrochemistry PY - 1998 SN - 0038-5387 SN - 1023-1935 VL - 34 IS - 10 SP - 1068 EP - 1075 PB - MAIK Nauka/Interperiodica Publ. CY - Moscow AN - OPUS4-826 LA - eng 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 - 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 - 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 - Kautek, Wolfgang A1 - Rudolph, Pascale A1 - Krüger, Jörg A1 - Rosenfeld, A. A1 - Lorenz, M. A1 - Ashkenasi, D. T1 - Morphological and mechanical investigations of bariumalumoborosilicate glass surfaces processed with 700-fs laser pulses JF - Applied physics A N2 - We present surface micro-modifications of bariumalumoborosilicate glasses with a high transformation temperature near 700 °C. Laser processing of the glass substrate was realized by using ultra-short laser pulses at 800 nm. The morphological conversion of the laser-treated surfaces was characterized by scanning force microscopy and nano-indentation. A hardness increase by at least a factor of six on the laser ablation crater edge relative to illuminated non- ablated areas shows that the material in the crater walls underwent drastic morphological and mechanical changes. In this heat- and shock-affected zone, the material became more elastic as a result of increased stress. T2 - 5th International Conference on Laser Ablation ; COLA '99 CY - Göttingen, Germany DA - 1999-07-19 KW - Bariumalumoborosilicate glass surfaces PY - 1999 DO - https://doi.org/10.1007/s003390051523 SN - 0947-8396 VL - 69 IS - 7 SP - S759 EP - S761 PB - Springer CY - Berlin AN - OPUS4-775 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Jörg A1 - Kautek, Wolfgang A1 - Newesely, H. T1 - Femtosecond-pulse laser ablation of dental hydroxyapatite and single-crystalline fluoroapatite JF - Applied physics A N2 - Laser microdrilling of healthy human enamel and dentine using 300 fs pulses at a wavelength of 615 nm and 3 Hz repetition rate leads to an enhanced structuring quality in comparison with nanosecond-laser results. Microcracking and damage to neighboring tissue can be reduced. Ablation threshold fluences for 100 laser pulses of 0.3 J cm-2 (human dentine), 0.6 J cm-2 (human enamel) and 0.8 J cm-2 (single crystalline fluoroapatite) could be determined. Ablation depths per pulse below 1 7m were observed. T2 - 5th International Conference on Laser Ablation ; COLA '99 CY - Göttingen, Germany DA - 1999-07-19 PY - 1999 DO - https://doi.org/10.1007/s003390051426 SN - 0947-8396 VL - 69 IS - 7 SP - S403 EP - S407 PB - Springer CY - Berlin AN - OPUS4-779 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 - Incubation of laser ablation in fused silica with 5-fs pulses JF - Applied physics A N2 - Zusammenfassung The threshold fluences for laser-induced damage of fused silica with single 5-fs pulses from a Ti:sapphire laser system were determined by extrapolating the ablated volume to zero. These thresholds are about 4 times as high as the values previously obtained from multi-shot experiments. This result is interpreted in terms of an irreversible modification of the original material below the single-shot threshold (incubation). KW - Laser PY - 1999 DO - https://doi.org/10.1007/s003390051034 SN - 0947-8396 VL - 69 IS - 4 SP - 465 EP - 466 PB - Springer CY - Berlin AN - OPUS4-799 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 - JOUR A1 - Rudolph, Pascale A1 - Bonse, Jörn A1 - Krüger, Jörg A1 - Kautek, Wolfgang T1 - Femtosecond- and nanosecond-pulse laser ablation of bariumalumoborosilicate glass JF - Applied physics A N2 - Laser ablation with femtosecond pulses (130 fs, wavelength 800 nm, repetition rate 2 Hz) was compared with nanosecond-pulse ablation (10 ns, wavelength 266 nm, repetition rate 2.5 Hz) of bariumalumoborosilicate glass in air using the direct focusing technique. Different ablation thresholds and heat-affected zones were observed. The lateral and vertical machining precision was evaluated. Single nanosecond laser pulses in the far UV resulted in a bubble or a circular hole in the centre of the illuminated spot, depending on the applied fluence. The ablation behaviour in the case of near-IR femtosecond pulses contrasted to this. Bubble formation was not detected. It needed repeated pulses at the same spot to modify the surface until material removal could be observed (incubation). Cavity dimensions of less than the beam diameter were achieved in this case. T2 - 5th International Conference on Laser Ablation ; COLA '99 CY - Göttingen, Germany DA - 1998-07-19 KW - Laser ablation KW - Bariumalumoborosilicate glass PY - 1999 DO - https://doi.org/10.1007/s003390051524 SN - 0947-8396 VL - 69 IS - 7 SP - S763 EP - S766 PB - Springer CY - Berlin AN - OPUS4-801 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Krüger, Jörg A1 - Lenzner, Matthias A1 - Martin, Sven A1 - Lenner, M. A1 - Spielmann, C. A1 - Fiedler, A. A1 - Kautek, Wolfgang ED - Phipps, C. R. T1 - Femtosecond laser induced damage in absorbing filters used for laser protection T2 - High-power laser ablation IV N2 - Damage experiments of absorbing filters (Schott BG18 and BG36) were performed with Ti:sapphire laser pulses with durations from 30 fs to 340 fs (800 nm, 1 kHz) in air. The direct focusing technique was employed under single- and multi-pulse irradiation conditions. Ablation threshold fluences were determined from a semi-logarithmic plot of the ablation crater diameter vs. laser fluence. The damage threshold fluence decreases for shorter pulse durations. In the investigated pulse duration range, the measured multi-pulse ablation threshold fluences are practically similar to those of undoped glass material (~1 Jcm-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 saturates. This leads to technically relevant damage threshold values in the femtosecond laser pulse duration domain. T2 - 4th SPIE's International Conference on High-Power Laser Ablation CY - Taos, NM, USA DA - 2002-04-22 KW - Ablation KW - Damage KW - Eye protection KW - Femtosecond pulse laser KW - Incubation KW - Laser safety KW - Threshold fluence PY - 2002 SN - 0-8194-4524-X DO - https://doi.org/10.1117/12.482109 SN - 1605-7422 N1 - Serientitel: SPIE proceedings series – Series title: SPIE proceedings series VL - 1 IS - 4760 SP - 398 EP - 405 PB - SPIE CY - Bellingham, Wash. AN - OPUS4-1550 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Kautek, Wolfgang A1 - Daminelli-Widany, Grazia A1 - Meja, P. A1 - Cortona, Anna A1 - Krüger, Jörg A1 - Autric, M. ED - Phipps, C. R. T1 - Femtosecond and nanosecond laser removal of anodic oxide layers from aluminium T2 - High-power laser ablation IV T2 - 4th SPIE's International Conference on High-Power Laser Ablation CY - Taos, NM, USA DA - 2002-04-22 KW - Laser ablation KW - Laser spallation KW - Microphone KW - Acoustical measurement KW - Aluminium oxide PY - 2002 SN - 0-8194-4524-X SN - 1605-7422 N1 - Serientitel: SPIE proceedings series – Series title: SPIE proceedings series IS - 4760 SP - 239 EP - 246 PB - SPIE CY - Bellingham, Wash. AN - OPUS4-1551 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Jörg A1 - Bonse, Jörn A1 - Lenzner, Matthias T1 - Modification and Ablation of Semiconductors by Femtosecond Laser Pulses JF - Recent research developments in applied physics N2 - Physical and chemical phenomena resulting from irradiation of silicon and indium phosphide with ultrashort laser pulses (~100fs) were investigated with respect to the difference between single- and multiple-pulse treatment. In the single-pulse case, several processes were identified: modification, recrystallization and ablation. All processes exhibit a distinct treshold behaviour. A two photon-absorption coefficient can be determined from a single spatial ablation profile. Accumulation effects were observed for multi-pulse illumination. Different morphological features like bubbles, rippels and microcolumns were found. PY - 2002 VL - 5 IS - 2 SP - 437 EP - 461 PB - Transworld Research Network CY - Trivandrum AN - OPUS4-1585 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kautek, Wolfgang A1 - Daminelli-Widany, Grazia A1 - Krüger, Jörg T1 - Femtosecond and Nanosecond Pulse Laser Electrochemistry of Aluminium Alloys T2 - Electrochemistry in molecular and microscopic dimensions T2 - 53th Annual meeting of the International Society of Electrochemistry CY - Düsseldorf, Germany DA - 2002-09-15 PY - 2002 SP - 1(?) PB - DECHEMA CY - Frankfurt a.M. AN - OPUS4-1586 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 - Bonse, Jörn A1 - Baudach, Steffen A1 - Kautek, Wolfgang A1 - Krüger, Jörg A1 - Welsch, E. T1 - Femtosecond laser damage of a high reflecting mirror JF - Thin solid films N2 - Multiple pulse investigations of 130-fs Ti:sapphire laser-induced damage of a high reflecting mirror consisting of alternating ?/4-layers of Ta2O5 and SiO2 and a single 500-nm Ta2O5 film were performed. In both cases, fused silica served as the substrate. For a fixed number of 1000 laser pulses per spot, a decrease in the damage threshold fluence of the mirror by a factor of two was observed by changing the repetition rate from 10 Hz to 1 kHz. A single 500-nm Ta2O5 film shows higher damage resistance compared to the mirror. The mirror and the Ta2O5 film samples were partially coated with a 300-nm-thick aluminium layer. The aluminium coating does not influence the damage threshold of the dielectrics underneath. KW - Aluminium KW - Laser ablation KW - Optical coatings KW - Silicon oxide PY - 2002 DO - https://doi.org/10.1016/S0040-6090(02)00074-3 SN - 0040-6090 IS - 408 SP - 297 EP - 301 PB - Elsevier CY - Amsterdam AN - OPUS4-1382 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Jörg A1 - Niino, Hiroyuki A1 - Yabe, A. T1 - Investigation of excimer laser ablation threshold of polymers using a microphone JF - Applied surface science N2 - KrF excimer laser ablation of polyethylene terephthalate (PET), polyimide (PI) and polycarbonate (PC) in air was studied by an in situ monitoring technique using a microphone. The microphone signal generated by a short acoustic pulse represented the etch rate of laser ablation depending on the laser fluence, i.e., the ablation “strength”. From a linear relationship between the microphone output voltage and the laser fluence, the single-pulse ablation thresholds were found to be 30 mJ cm-2 for PET, 37 mJ cm-2 for PI and 51 mJ cm-2 for PC (20-pulses threshold). The ablation thresholds of PET and PI were not influenced by the number of pulses per spot, while PC showed an incubation phenomenon. A microphone technique provides a simple method to determine the excimer laser ablation threshold of polymer films. KW - Laser ablation KW - Polymer KW - Treshold KW - Microphone KW - Acoustic measurement KW - Incubation PY - 2002 DO - https://doi.org/10.1016/S0169-4332(02)00418-X SN - 0169-4332 SN - 1873-5584 VL - 197-198 SP - 800 EP - 804 PB - North-Holland CY - Amsterdam AN - OPUS4-1920 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg T1 - Femtosecond Laser Micromachining: Potentials, Applications, Safety Aspects T2 - Materials Seminar Series, Paul Scherrer Institut T2 - Materials Seminar Series, Paul Scherrer Institut CY - Villigen, Switzerland DA - 2003-05-19 PY - 2003 AN - OPUS4-4360 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - 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 - 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 - Krüger, Jörg A1 - Martin, Sven A1 - Mädebach, Heinrich A1 - Urech, L. A1 - Lippert, T. A1 - Wokaun, A. A1 - Kautek, Wolfgang T1 - Femto- and nanosecond laser treatment of doped polymethylmethacrylate JF - Applied surface science N2 - Femto- and nanosecond laser ablation of polymethylmethacrylate (PMMA) and PMMA doped with a linear absorber was investigated in the infrared spectral region. Ablation thresholds were determined and incubation phenomena were identified. The ‘degree’ of incubation was calculated employing a phenomenological model. The influence of the pulse duration on the machining quality of the polymers was examined. The presence of an absorbing chromophore is not a prerequisite for a controllable fs-laser structuring in contrast to the ns-treatment. Surface swelling always accompanied ablation. KW - Laser ablation KW - Laser beam machining KW - Doping thin films KW - Polymers-radiation effects PY - 2005 DO - https://doi.org/10.1016/j.apsusc.2005.01.078 SN - 0169-4332 SN - 1873-5584 VL - 247 SP - 406 EP - 411 PB - North-Holland CY - Amsterdam AN - OPUS4-7470 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Daminelli-Widany, Grazia A1 - Krüger, Jörg A1 - Kautek, Wolfgang T1 - Femtosecond laser interaction with silicon under water confinement JF - Thin solid films N2 - Femtosecond laser interaction with silicon was investigated in water and in air, with 130-fs laser pulses at 800 nm wavelength. Under water confinement, higher modification thresholds, lower ablation depths and similar incubation factors were found in comparison to the dry experiment. Morphological features of the laser-induced cavities also differed. In contrast to air experiments, debris redeposition was negligible, while the ablated material remained suspended in the water layer phase. Underwater cavities obtained at high fluences and high number of pulses per spot showed anomalous profiles, consistent with a strong spatial deformation of the laser beam coupled into the target. Ripples formed at the edges of the modified area showed varying spacings: f100 and f700 nm for water and air experiments, respectively. Differences to the air experiment were related to a complex combination of fluence-dependent non-linear effects occurring in the water layer and to pulse-number-dependent shielding effects induced by cavitation bubbles and suspended ablated material. KW - Laser ablation KW - Silicon KW - Solid electrolyte interface KW - Water PY - 2004 DO - https://doi.org/10.1016/j.tsf.2004.04.043 SN - 0040-6090 VL - 467 IS - 1-2 SP - 334 EP - 341 PB - Elsevier CY - Amsterdam AN - OPUS4-4008 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Krüger, Jörg A1 - Kautek, Wolfgang A1 - Staub, M. A1 - Scherer, G.G. ED - Waidelich, W. T1 - Femtosecond-pulse laser micromachining of metal layer composites T2 - Laser in Forschung und Technik = Laser in research and engineering T2 - 12. Internationalen Kongresses Laser 95 CY - Berlin, Germany DA - 1996-01-01 PY - 1996 SN - 3-540-61316-1 SP - 966 EP - 969 PB - Springer CY - Berlin AN - OPUS4-11958 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Kautek, Wolfgang A1 - Krüger, Jörg ED - Beyer, E. T1 - Femtosecond pulse laser ablation of metallic, semiconducting, ceramic, and biological materials T2 - Laser materials processing N2 - Production of holes and grooves of < 30 micrometers diameter with high aspect ratio value is a delicate task either for mechanical tools, or for conventional nanosecond pulse lasers like e.g. pulsed Nd:YAG or excimer lasers. They later tend to cause microcracks extending from an annular melting zone, or substantial disruption, respectively. Experimental results are presented which demonstrate that the development of intense ultrashort pulse laser systems (>> 1012 W cm-2, (tau) < 1 ps) opens up possibilities for materials processing by cold plasma generation and ablation of metals, semiconductors, ceramics, composites, and biological materials. A femtosecond and a nanosecond dye laser with pulse durations of 300 fs (< 200 (mu) J) and 7 ns (< 10 mJ), and center wavelengths at 612 and 600 nm, respectively, both focused on an area of the order of 10-5 cm2, have been applied either to absorbing substrates, like polycrystalline gold, silicon (111), aluminum nitride ceramics, or transparent materials, like synthetic and human dental hydroxyapatite composites, bone material, and human cornea transplants. The fs-laser generates its own absorption in transparent materials by a multiphoton absorption process, and thus forces the absorption of visible radiation. Because the time is too short (< ps) for significant transport of mass and energy, the beam interaction generally results in the formation of a thin plasma layer of approximately solid state density. Only after the end of the subpicosecond laser pulse, it expands rapidly away from the surface without any light absorption and further plasma heating. Therefore, energy transfer (heat and impulse) to the target material, and thermal and mechanical disruption are minimized. In contrast to heat- affected zones (HAZ's) generated by conventional nanosecond pulse lasers of the order of 1 - 10 micrometers , HAZ's of less than 0.02 micrometers were observed. T2 - Conference on Production Line Processes ; Conference on Process Control and Modeling ; Conference on Novel Applications CY - Vienna, Austria DA - 1994-04-05 PY - 1994 SN - 0-8194-1508-1 DO - https://doi.org/10.1117/12.184768 SN - 1605-7422 N1 - Serientitel: SPIE proceedings series – Series title: SPIE proceedings series IS - 2207 SP - 600 EP - 611 PB - SPIE--the International Society for Optical Engineering CY - Bellingham, Wash. AN - OPUS4-11892 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 - GEN A1 - Gruber, D. A1 - Husinsky, W. A1 - Grabner, G. A1 - Baumgartner, I. A1 - Scholman, J. A1 - Krüger, Jörg A1 - Kautek, Wolfgang ED - Waidelich, W. T1 - Nano- and Femtosecond-Laser Processing of Human Donor Corneal-Transplants and Lenticules for Corneal Surgery T2 - Laser in Forschung und Technik = Laser in research and engineering T2 - 12. Internationaler Kongress Laser 95 CY - Munich, Germany DA - 1995-06-01 PY - 1996 SN - 3-540-61316-1 SP - 397 EP - 400 PB - Springer CY - Berlin AN - OPUS4-11895 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Simone A1 - Schulze, Rolf-Dieter A1 - Brademann-Jock, Kerstin A1 - Friedrich, Jörg Florian ED - Pershin, L. T1 - Introduction of irregularities into plasma polymers by radiative and auto-oxidative processes T2 - Proceedings of the 17th International Symposium on Plasma Chemistry T2 - 17th International Symposium on Plasma Chemistry (ISPC-17) CY - Toronto, Canada DA - 2005-08-07 PY - 2005 SP - 1(?) EP - 6(?) CY - Toronto AN - OPUS4-11943 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Falkenhagen, Jana A1 - Krüger, Ralph-Peter A1 - Rikowski, Eckhard A1 - Schulz, Günter A1 - Friedrich, Jörg Florian ED - Grellmann, W. T1 - Synthesis and Characterisation of Polyhedral Silsesquioxanes with Nanotubular Structures T2 - Tagungsband der 23. DVM-Vortrags- und Diskussionstagung "Werkstoffprüfung 2005" T2 - 23. DVM-Vortrags- und Diskussionstagung "Werkstoffprüfung 2005", DA - 2005-12-01 PY - 2005 SP - 25 EP - 30 PB - DVM AN - OPUS4-11947 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 - 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 - Kautek, Wolfgang A1 - Krüger, Jörg ED - Brieger, M. T1 - Femtosecond-pulse laser microstructuring of semiconducting materials T2 - Semiconductor processing and characterization with lasers 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 - Subpicosecond-Pulse Laser KW - Laser-Ablation KW - Multi-Photon Absorption KW - Microstructuring KW - Dry Etching KW - Semiconductors KW - Silicon PY - 1995 SN - 0-87849-683-1 SN - 0255-5476 N1 - Serientitel: Materials science forum – Series title: Materials science forum IS - 173/174 SP - 17 EP - 22 PB - Trans Tech Publ. CY - Aedermannsdorf AN - OPUS4-11671 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Jörg A1 - Sorg, N. A1 - Reif, J. A1 - Kautek, Wolfgang T1 - In situ second harmonic generation measurements during the electrodeposition of Ni on n-Si(111) JF - Applied surface science PY - 1993 SN - 0169-4332 SN - 1873-5584 VL - 69 SP - 388 EP - 392 PB - North-Holland CY - Amsterdam AN - OPUS4-11657 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 - Kautek, Wolfgang A1 - Mitterer, S. A1 - Krüger, Jörg A1 - Husinsky, W. A1 - Grabner, G. T1 - Femtosecond-Pulse Laser Ablation of Human Corneas JF - Applied physics A N2 - A femtosecond pulse laser in the visible spectral region shows promise as a potentially new powerful corneal sculpting tool. It combines the clinical and technical advantages of visible wavelengths with the high ablation quality observed with nanosecond-pulse excimer lasers at 193 nm. A femtosecond and a nanosecond dye laser with pulse durations of 300 fs and 7 ns, and centre wavelengths at 615 nm and 600 nm, respectively, both focused to an area of the order of 10–5 cm2, have been applied to human corneal ablation. Nanosecond laser pulses caused substantial tissue disruption within a 30–100 m range from the excision edge at all fluences above the ablation threshold of F th60 J cm–2 (I th9 GW cm–2). Completely different excisions are produced by the femtosecond-pulse laser: high quality ablations of the Bowman membrane and the stroma tissue characterised by damage zones of less than 0.5 m were observed at all fluences above ablation threshold of F th1 J cm–2 or I th3 TW cm–2 (3×1012 W cm–2). The transparent cornea material can be forced to absorb ultrashort pulses of extremely high intensity. The fs laser generates its own absorption by a multiphoton absorption process. PY - 1994 DO - https://doi.org/10.1007/BF00332446 SN - 0947-8396 VL - 58 IS - 5 SP - 513 EP - 518 PB - Springer CY - Berlin AN - OPUS4-11659 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kautek, Wolfgang A1 - Sorg, N. A1 - Krüger, Jörg T1 - Femtosecond pulse laser second harmonic generation on semiconductor electrodes JF - Electrochimica acta KW - Femtosecond pulse laser KW - Second harmonic generation (SHG) KW - Electrochemistry KW - Semiconductor electrode KW - Silicon KW - Silicon oxide KW - Oxide growth PY - 1994 SN - 0013-4686 SN - 1873-3859 VL - 39 IS - 8/9 SP - 1245 EP - 1249 PB - Elsevier Science CY - Kidlington AN - OPUS4-11660 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg A1 - Dufft, Daniela A1 - Koter, Robert A1 - Hertwig, Andreas T1 - Femtosecond laser-induced damage of gold films T2 - E-MRS 2006 Spring Meeting, Symposium H T2 - E-MRS 2006 Spring Meeting, Symposium H CY - Nice, France DA - 2006-05-29 PY - 2006 AN - OPUS4-12252 LA - eng 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 - Friedrich, Jörg Florian A1 - Möller, B. A1 - Kühn, Gerhard A1 - Unger, Wolfgang A1 - Krüger, P. T1 - Improvement of adhesion properties of polymers by producing oxyfluorinated surfaces JF - Galvanotechnik PY - 2001 SN - 0016-4232 VL - 92 IS - 5 SP - 1334 EP - 1444 PB - Leuze CY - Saulgau, Württ. AN - OPUS4-6973 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, P. A1 - Knes, R. A1 - Friedrich, Jörg Florian T1 - Surface cleaning by plasma-enhanced desorption of contaminants JF - Surface and coatings technology PY - 1999 SN - 0257-8972 VL - 112 SP - 240 EP - 244 PB - Elsevier Science CY - Lausanne AN - OPUS4-6984 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, P. A1 - Friedrich, Jörg Florian A1 - Meyer-Plath, Asmus T1 - Selective chemical modification of porous materials and films for bio-medical applications T2 - Abstracts booklet of the CIP 2003 ([Vide - science, technique et applications] ; 2003 [No. spéc.]) T2 - CIP 2003 ; 14th International Colloquium on Plasma Processes CY - Antibes, France DA - 2003-06-30 PY - 2003 SP - 1(?) EP - 4(?) PB - sfv, Sociéte Française du Vide CY - Paris AN - OPUS4-6963 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Jörg A1 - Martin, Sven A1 - Mädebach, Heinrich A1 - Kautek, Wolfgang A1 - Urech, L. A1 - Lippert, Th. A1 - Wokaun, A. T1 - Femto- and Nanosecond Laser Treatment of Doped Polymethylmethacrylate T2 - E-MRS 2004 Spring Meeting T2 - E-MRS 2004 Spring Meeting CY - Strasbourg, France DA - 2004-08-24 PY - 2004 AN - OPUS4-4145 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 - GEN A1 - Kautek, Wolfgang A1 - Pentzien, Simone A1 - Krüger, Jörg A1 - König, E. ED - Kautek, W. ED - König, E. T1 - Laser cleaning of ancient parchments T2 - Lasers in the conservation of artworks T2 - LACONA I CY - Heraklion, Crete, Greece DA - 1995-10-04 PY - 1997 SN - 3-901025-68-5 VL - 18 SP - 69 EP - 78 PB - Mayer CY - Klosterneuburg AN - OPUS4-11784 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 - 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 - JOUR A1 - Baudach, Steffen A1 - Krüger, Jörg A1 - Kautek, Wolfgang T1 - Femtosecond Laser Processing of Soft Materials JF - R¯ez¯a-kenky¯u = Review of laser engineering KW - Femtosecond pulse laser KW - Laser processing KW - Polymer ablation KW - Nanostructures PY - 2001 SN - 0387-0200 VL - 29 IS - 11 SP - 705 EP - 709 PB - Gakkai CY - Suita AN - OPUS4-6006 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Bonse, Jörn A1 - Baudach, Steffen A1 - Krüger, Jörg A1 - Kautek, Wolfgang ED - Exarhos, G. T1 - Femtosecond laser damage in dielectric coatings T2 - Laser-induced damage in optical materials - 2000 N2 - Multi-shot investigations of Ti:sapphire laser (wavelength (lambda) approximately equals 800 nm) induced damage were performed in three different laboratories (BAM, Berlin; LZH, Hannover; UNM, Albuquerque). The ablation behavior of a high reflecting mirror consisting of alternating (lambda) /4- layers of Ta2O5 and SiO2 was studied. Fused silica served as substrate. The influence of the pulse duration ((tau) equals 13 - 130 fs), the pulse number (30 - (infinity) ) and the repetition rate (10 Hz - 100 MHz) on the damage threshold will be discussed. T2 - 32nd Annual Boulder Damage Symposium CY - Boulder, CO, USA DA - 2000-10-16 PY - 2001 SN - 0-8194-4036-1 DO - https://doi.org/10.1117/12.425056 SN - 1605-7422 N1 - Serientitel: SPIE proceedings series – Series title: SPIE proceedings series IS - 4347 SP - 24 EP - 34 PB - International Society for Optical Engineering (SPIE) CY - Bellingham, Wash. AN - OPUS4-6013 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hertwig, Andreas A1 - Martin, Sven A1 - Krüger, Jörg A1 - Kautek, Wolfgang T1 - Interaction area dependence of the ablation threshold of ion-doped glass JF - Thin solid films N2 - The laser ablation behaviour of ion-doped glass filter materials under irradiation with femtosecond laser pulses was investigated with respect to spot size and repetition rate. The damage threshold fluence of Schott BG18 depends on the size of the irradiated area. The effect is discussed in terms of a defect-site model. KW - Femtosecond KW - Laser KW - Materials processing KW - Ablation KW - Threshold KW - Glass PY - 2004 DO - https://doi.org/10.1016/j.tsf.2003.11.131 SN - 0040-6090 VL - 453-454 SP - 527 EP - 530 PB - Elsevier CY - Amsterdam AN - OPUS4-11046 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 - Daminelli-Widany, Grazia A1 - Pentzien, Simone A1 - Hertwig, Andreas A1 - Krüger, Jörg T1 - Influence of film thickness on laser ablation of hydrogenated amorphous carbon films JF - Applied physics N2 - Single-pulse damage thresholds of hydrogenated amorphous carbon (a-C:H) films were measured for 8-ns laser pulses at 532-nm wavelength. Layer thicknesses from below the optical penetration depth to above the thermal diffusion length (60 nm–13 µm) were examined. After correction of the damage-threshold values for the fraction of energy effectively absorbed by the material, the damage threshold was found to increase linearly with the layer thickness, also for film thicknesses below the optical penetration depth of a-C:H. The threshold fluence reached the bulk value for a layer thickness equal to the thermal diffusion length. The thermal diffusion coefficient was obtained from fitting the experimental data. Several phenomena like graphitization, blistering, exfoliation, and ablation were observed for different fluence regimes and film thicknesses. PY - 2006 DO - https://doi.org/10.1007/s00339-005-3460-5 SN - 0340-3793 VL - 83 IS - 1 SP - 89 EP - 94 PB - Springer CY - Berlin AN - OPUS4-12022 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 - 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 - 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 - 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 - CONF A1 - Pentzien, Simone A1 - Rabin, Ira A1 - Hahn, Oliver A1 - Krüger, Jörg A1 - Kleber, F. A1 - Hollaus, F. A1 - Diem, M. A1 - Sablatnig, R. ED - Park, J.-I. ED - Kim, J. T1 - Can Modern Technologies Defeat Nazi Censorship? T2 - ACCV 2012 Workshops, 11th Asian conference on computer vision N2 - Censorship of parts of written text was and is a common practice in totalitarian regimes. It is used to destroy information not approved by the political power. Recovering the censored text is of interest for historical studies of the text. This paper raises the question, whether a censored postcard from 1942 can be made legible by applying multispectral imaging in combination with laser cleaning. In the fields of art conservation (e.g. color measurements), investigation (e.g. Analysis of underdrawings in paintings), and historical document analysis, multispectral imaging techniques have been applied successfully to give visibility to information hidden to the human eye. The basic principle of laser cleaning is to transfer laser pulse energy to a contamination layer by an absorption process that leads to heating and evaporation of the layer. Partial laser cleaning of postcards is possible; dirt on the surface can be removed and the obscured pictures and writings made visible again. We applied both techniques to the postcard. The text could not be restored since the original ink seems to have suffered severe chemical damage. T2 - ACCV 2012 Workshops, 11th Asian conference on computer vision CY - Daejeon, Korea DA - 05.11.2012 KW - Laser cleaning KW - Multispectral imaging KW - Image restoration KW - Image enhancement PY - 2013 SN - 978-3-642-37483-8 SN - 0302-9743 VL - II IS - LNCS 7729 SP - 13 EP - 24 PB - Springer CY - Berlin Heidelberg AN - OPUS4-28160 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mann, Guido A1 - Pentzien, Simone A1 - Krüger, Jörg T1 - Beam diameter dependence of surface damage threshold of fused silica fibers and preforms for nanosecond laser treatment at 1064 nm wavelength JF - Applied surface science N2 - Optical fibers made of fused silica are a common method of transmitting high laser pulse energies. Failure of those fibers is a significant risk. The determination of laser-induced damage thresholds (LIDT) on fiber end facets according to ISO 21254 standard is needed. In the past, single pulse nanosecond laser experiments showed an improvement of LIDT with increasing fiber core diameter for 1064 nm wavelength and a constant beam diameter of 50 µm. This paper pays particular attention to the influence of the laser beam diameter on damage resistance. All-silica fiber types (LEONI) with different core diameters (100–600 µm) were investigated using beam diameters in a range from 30 µm to 100 µm. For comparison experiments on fused silica preform material (Heraeus F300) were performed. On one hand, surface LIDT of fused silica preform material decreases significantly with increasing beam size. A model considering a random distribution of point defects explains the experimental data qualitatively. On the other hand, LIDT of fiber end facets stays constant. White light microscopy results suggest that the point defect density on fiber end facets is lower compared to the preform surface due to an excellent surface polish quality. KW - Laser-induced damage threshold KW - Nanosecond laser KW - Optical fiber KW - Fused silica KW - Spot size KW - Defect model PY - 2013 DO - https://doi.org/10.1016/j.apsusc.2013.03.088 SN - 0169-4332 SN - 1873-5584 VL - 276 SP - 312 EP - 316 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-28310 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mohamed, Zeinab A1 - Krüger, Simone A1 - Hidde, Gundula A1 - Schimanski, A. A1 - Jäger, Christian A1 - Friedrich, Jörg Florian T1 - Deposition of thick polymer or inorganic layers with flame-retardant properties by combination of plasma and spray processes JF - Surface and coatings technology N2 - Mixtures of hexamethyldisiloxane (HMDSO) and oxygen have been used for deposition of SiO2-like layers by plasma polymerization under low-pressure conditions onto polyethylene and polystyrene used as basecoat. Water glass was cast onto these 0.5 µm plasma thick siloxane-like layers with a thickness of 5 to 40 µm. The adhesion of these bilayer systems and their flame resistance were tested. The effect of different plasma parameters such as monomer/gas ratio, pressure and power input into the discharge on the deposition rate and the composition of the formed layers was studied. Characterization and chemical composition of the formed films were performed using infrared, X-ray photoelectron and solid state nuclear magnetic resonance spectroscopy. Peel strengths of composites were measured and the locus of peel front propagation was detected. Thermal properties of composites were analyzed by thermo-gravimetric analysis. Finally, the fire-retardant properties of thick coated polymers were determined by exposure to flames and the behavior of coatings on the polymers during flaming was observed visually. KW - Plasma polymerization KW - Hexamethyldisiloxane plasma polymer KW - Polystyrene KW - Polyethylene KW - Flame retardancy PY - 2013 DO - https://doi.org/10.1016/j.surfcoat.2013.04.039 SN - 0257-8972 VL - 228 SP - 266 EP - 274 PB - Elsevier B.V. CY - Lausanne AN - OPUS4-28735 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pentzien, Simone A1 - Rabin, Ira A1 - Hahn, Oliver A1 - Krüger, Jörg A1 - Kleber, F. A1 - Hollaus, F. A1 - Diem, M. A1 - Sablatnig, R. T1 - Can modern technologies defeat nazi censorship? JF - ACM journal on computing and cultural heritage KW - Laser cleaning KW - Multispectral imaging KW - Image enhancement KW - Ancient manuscripts KW - Image restoration PY - 2010 SN - 1556-4673 VL - 2 IS - 3, Article 1 SP - 1 EP - 16 PB - Association for Computing Machinery CY - New York, NY, USA AN - OPUS4-25651 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Krüger, Jörg A1 - Höhm, S. A1 - Rosenfeld, A. T1 - Femtosecond laser-induced periodic surface structures JF - Journal of laser applications N2 - The formation of laser-induced periodic surface structures (LIPSS) in different materials (metals, semiconductors, and dielectrics) upon irradiation with linearly polarized fs-laser pulses (τ~30–150 fs, λ~800 nm) in air environment is studied experimentally and theoretically. In metals, predominantly low-spatial-frequency-LIPSS with periods close to the laser wavelength λ are observed perpendicular to the polarization. Under specific irradiation conditions, high-spatial-frequency-LIPSS with sub-100-nm spatial periods (~λ/10) can be generated. For semiconductors, the impact of transient changes of the optical properties to the LIPSS periods is analyzed theoretically and experimentally. In dielectrics, the importance of transient excitation stages in the LIPSS formation is demonstrated experimentally using (multiple) double-fs-laser-pulse irradiation sequences. A characteristic decrease of the LIPSS periods is observed for double-pulse delays of less than 2 ps. KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser ablation KW - Ultrafast optical techniques KW - Silicon KW - Titanium KW - Silica PY - 2012 DO - https://doi.org/10.2351/1.4712658 SN - 1042-346X SN - 1938-1387 VL - 24 IS - 4 SP - 042006-1 EP - 042006-7 PB - Laser Institute of America CY - Orlando, Fla., USA AN - OPUS4-26198 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Symietz, Christian A1 - Lehmann, Erhard A1 - Gildenhaar, Renate A1 - Hackbarth, Andreas A1 - Berger, Georg A1 - Krüger, Jörg T1 - Mechanical stability of Ti6Al4V implant material after femtosecond laser irradiation JF - Journal of applied physics N2 - The surface of a titanium alloy (Ti6Al4V) implant material was covered with a bioactive calcium alkali phosphate ceramic with the aim to accelerate the healing and to form a stronger bond to living bone tissue. To fix the ceramic powder we used a femtosecond laser, which causes a thin surface melting of the metal. It is a requirement to prove that the laser irradiation would not reduce the lifetime of implants. Here we present the results of mechanical stability tests, determined by the rotating bending fatigue strength of sample rods. After describing the sample surfaces and their modifications caused by the laser treatment we give evidence for an unchanged mechanical stability. This applies not only to the ceramic fixation but also to a comparatively strong laser ablation. KW - Aluminium alloys KW - Bending strength KW - Bioceramics KW - Bone KW - Calcium compounds KW - Fatigue KW - Fatigue testing KW - High-speed optical techniques KW - Laser ablation KW - Melting KW - Orthopaedics KW - Prosthetics KW - Rods (structures) KW - Surface treatment KW - Titanium alloys KW - Vanadium alloys PY - 2012 DO - https://doi.org/10.1063/1.4737576 SN - 0021-8979 SN - 1089-7550 VL - 112 IS - 2 SP - 023103-1 - 023103-5 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-26200 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Höhm, S. A1 - Rosenfeld, A. A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Femtosecond laser-induced periodic surface structures on silica JF - Journal of applied physics N2 - The formation of laser-induced periodic surface structures (LIPSS) on two different silica polymorphs (single-crystalline synthetic quartz and commercial fused silica glass) upon irradiation in air with multiple linearly polarized single- and double-fs-laser pulse sequences (τ = 150 fs pulse duration, λ = 800nm center wavelength, temporal pulse separation Δt < 40 ps) is studied experimentally and theoretically. Two distinct types of fs-LIPSS [so-called low-spatial-frequency LIPSS (LSFL) and high-spatial-frequency LIPSS (HSFL)] with different spatial periods and orientations were identified. Their appearance was characterized with respect to the experimental parameters peak laser fluence and number of laser pulses per spot. Additionally, the 'dynamics' of the LIPSS formation was addressed in complementary double-fs-pulse experiments with varying delays, revealing a characteristic change of the LSFL periods. The experimental results are interpreted on the basis of a Sipe-Drude model considering the carrier dependence of the optical properties of fs-laser excited silica. This new approach provides an explanation of the LSFL orientation parallel to the laser beam polarisation in silica—as opposed to the behaviour of most other materials. KW - High-speed optical techniques KW - Laser beam effects KW - Refractive index KW - Silicon compounds KW - Surface structure PY - 2012 DO - https://doi.org/10.1063/1.4730902 SN - 0021-8979 SN - 1089-7550 VL - 112 IS - 1 SP - 014901-1 - 014901-9 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-26201 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kotsifaki, D.G. A1 - Zekou, L. A1 - Pentzien, Simone A1 - Krüger, Jörg A1 - Serafetinides, A.A. ED - Saunders, D. ED - Strlic, M. ED - Korenberg, C. ED - Luxford, N. ED - Birkhölzer, K. T1 - Cleaning of artificially soiled papers by infrared and mid-infrared lasers T2 - LACONA IX - Lasers in the conservation of artworks (Proceedings) N2 - One of the most important materials presenting and witnessing human culture is paper. The cleaning of paper is often necessary because contamination must be removed so that the fragile organic substrate can be preserved. The conventional cleaning methods are mechanical or involve the application of chemicals. These methods can damage drawings or print layers to some extent or make the original paper substrate brittle. More specifically, the use of a scalpel blade can cause damage to fibers. Chemical cleaning is difficult to perform locally, can dissolve foreign matter that then migrates into the paper substrate, or involves volatile organic compounds that can be harmful to the conservator. There is, therefore, a need for new conservation technologies aimed at the safe cleaning of paper. Lasers have proved to be an appropriate tool for cleaning as the energy dose and penetration depth at the specific point of contamination can be controlled. Additionally, if used properly, laser cleaning is not destructive to the paper. T2 - LACONA IX - Lasers in the conservation of artworks CY - London, UK DA - 07.09.2011 KW - Laser cleaning KW - Paper KW - Artificial soiling KW - Nanosecond laser KW - Microsecond laser PY - 2013 SN - 978-1-904982-87-6 SP - 219 EP - 221 PB - Archetype publications Ltd. AN - OPUS4-27956 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mohamed, Zeinab A1 - Krüger, Simone A1 - Friedrich, Jörg Florian T1 - Deposition of thick polymer or inorganic layers with flame-retardant properties by combination of plasma and spray processes T2 - 3. Magdeburger Brand- und Explosionsschutztag / vfdb-Workshop N2 - Mixtures of hexamethyldisiloxane (HMDSO) and oxygen have been used for deposition of SiO2-like layers by plasma polymerization under low-pressure conditions onto polyethylene and polystyrene used as basecoat. Water glass was cast onto these 0.5 pm plasma thick siloxane-like layers with a thickness of 5 to 40 mu m. The adhesion of these bilayer systems and their flame resistance were tested. The effect of different plasma parameters such as monomer/gas ratio, pressure and power input into the discharge on the deposition rate and the composition of the formed layers was studied. Characterization and chemical composition of the formed films were performed using infrared, X-ray photoelectron and solid state nuclear magnetic resonance spectroscopy. Peel strengths of composites were measured and the locus of peel front propagation was detected. Thermal properties of composites were analyzed by thermo-gravimetric analysis. Finally, the fire-retardant properties of thick coated polymers were determined by exposure to flames and the behavior of coatings on the polymers during flaming was observed visually. T2 - 3. Magdeburger Brand- und Explosionsschutztag / vfdb-Workshop CY - Magdeburg, Germany DA - 21.03.2013 KW - Polymer KW - Plasmatechnologie KW - Analytik PY - 2013 SN - 978-3-00-041601-9 SP - 1 EP - 11 AN - OPUS4-27988 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Höhm, S. A1 - Rosenfeld, A. A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Area dependence of femtosecond laser-induced periodic surface structures for varying band gap materials after double pulse excitation JF - Applied surface science N2 - The formation of laser-induced periodic surface structures upon irradiation of titanium, silicon, and fused silica with multiple irradiation sequences consisting of parallel polarized Ti:sapphire femtosecond laser pulse pairs (pulse duration 50–150 fs, central wavelength ~800 nm) is studied experimentally. The temporal delay between the individual near-equal energy fs-laser pulses was varied between 0 and 5 ps with a temporal resolution of better than 0.2 ps. The surface morphology of the irradiated surface areas is characterized by means of scanning electron microscopy (SEM). In all materials a decrease of the rippled surface area is observed for increasing delays. The characteristic delay decay scale is quantified and related to material dependent excitation and energy relaxation processes. KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser ablation KW - Double-pulse experiments KW - Ultrafast optical techniques KW - Mach-Zehnder interferometer PY - 2013 DO - https://doi.org/10.1016/j.apsusc.2012.10.188 SN - 0169-4332 SN - 1873-5584 VL - 278 SP - 7 EP - 12 PB - North-Holland CY - Amsterdam AN - OPUS4-28601 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Hertwig, Andreas A1 - Koter, Robert A1 - Weise, Matthias A1 - Beck, Uwe A1 - Reinstädt, Philipp A1 - Griepentrog, Michael A1 - Krüger, Jörg A1 - Picquart, M. A1 - Haro-Poniatowski, E. T1 - Femtosecond laser pulse irradiation effects on thin hydrogenated amorphous carbon layers JF - Applied physics A N2 - The irradiation of ~0.9-µm-thick hydrogenated amorphous carbon (a-C:H) layers deposited on silicon substrates with single femtosecond (fs) laser pulses (35 fs pulse duration, 790 nm centre wavelength) in air is studied experimentally. Irradiation spots have been generated with different peak fluences and subsequently investigated by optical topometry, micro Raman spectroscopy and microscale mechanical indentation in order to evaluate their microscopic, topographical, structural and mechanical properties (e.g. elastic modulus). By this multi-method approach, a clear separation of different effects (delamination and graphitisation) becomes possible. The joint application of mechanical and spectroscopic techniques provides unique insights into the effects of the fs-laser radiation on the carbon layer. PY - 2013 DO - https://doi.org/10.1007/s00339-012-7170-5 SN - 0947-8396 VL - 112 IS - 1 SP - 9 EP - 14 PB - Springer CY - Berlin AN - OPUS4-28629 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Geier, M. A1 - Eberstein, M. A1 - Grießmann, H. A1 - Partsch, U. A1 - Völkel, L. A1 - Böhme, R. A1 - Mann, Guido A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - Impact of laser treatment on phosphoric acid coated multicrystalline silicon PV-wafers T2 - 26th European photovoltaic solar energy conference and exhibition (Proceedings) N2 - The selective emitter is a well-known technology for producing highly doped areas under the metallization grid to improve the solar cell performance. In this work, the influence of laser irradiation on phosphoric acid coated multicrystalline silicon PV-wafers on the wafer surface structure, the phosphorous depth distribution and the electrical contact resistance within the laser treated area as well as the electrical series resistance of laserprocessed solar cells was evaluated. Different laser processing settings were tested including pulsed and continuous wave (cw) laser sources (515 nm, 532 nm, 1064 nm wavelength). Complementary numerical simulations using the finite element method (FEM) were conducted to explain the impact of the laser parameters on the melting behavior (melt duration and geometry). It was found that the melt duration is a key parameter for a successful laser Doping process. Our simulations at a laser wavelengths of 515 nm reveal that low-repetition rate (<500 kHz) laser pulses of 300 ns duration generate a melt duration of ~0.35 µs, whereas upon scanning cw-laser radiation at 532 nm prolongates the melt duration by at least one order of magnitude. Experimentally, the widely used ns-laser pulses did not lead to satisfying laser irradiation results. In contrast, cw-laser radiation and scan velocities of less than 2 m/s led to suitable laser doping featuring low electrical resistances in the laser treated areas. T2 - 26th European photovoltaic solar energy conference and exhibition CY - Hamburg, Germany DA - 05.09.2011 KW - Silicon solar cell KW - Selective emitter KW - Laser processing KW - Doping KW - Simulation PY - 2011 SN - 3-936338-27-2 DO - https://doi.org/10.4229/26thEUPVSEC2011-2BV.1.7 SP - 1243 EP - 1247 AN - OPUS4-24995 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 - JOUR A1 - Höhm, S. A1 - Rosenfeld, A. A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Femtosecond diffraction dynamics of laser-induced periodic surface structures on fused silica JF - Applied physics letters N2 - The formation of laser-induced periodic surface structures (LIPSS) on fused silica upon irradiation with linearly polarized fs-laser pulses (50 fs pulse duration, 800?nm center wavelength) is studied experimentally using a transillumination femtosecond time-resolved (0.1 ps-1 ns) pump-probe diffraction approach. This allows to reveal the generation dynamics of near-wavelength-sized LIPSS showing a transient diffraction at specific spatial frequencies even before a corresponding permanent surface relief was observed. The results confirm that the ultrafast energy deposition to the materials surface plays a key role and triggers subsequent physical mechanisms such as carrier scattering into self-trapped excitons. KW - High-speed optical techniques KW - Laser beam effects KW - Silicon compounds KW - Surface structure PY - 2013 DO - https://doi.org/10.1063/1.4790284 SN - 0003-6951 SN - 1077-3118 VL - 102 IS - 5 SP - 054102-1 EP - 054102-4 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-27646 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mann, Guido A1 - Zoheidi, M. A1 - Krüger, Jörg T1 - High performance fibers at the limit JF - Laser + Photonik N2 - Because of the increasingly stringent requirements for fibers in high Performance applications, the Business Unit Fiber Optics of the Leoni Group and the German BAM Federal Institute for Materials Research and Testing are jointly tackling the challenge of investigating the damage thresholds of selected large core special fibers for the first time. KW - Laser-induced damage threshold KW - Optical multimode fiber KW - Nanosecond laser PY - 2013 SN - 1610-3521 IS - Laser+Photonics Exportausgabe 2013 SP - 20 EP - 23 PB - Hanser CY - München AN - OPUS4-27679 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mann, Guido A1 - Jurke, Mathias A1 - Zoheidi, M. A1 - Krüger, Jörg T1 - Influence of mechanical stress on nanosecond laser-induced damage threshold of fused silica JF - Applied surface science N2 - Optical multimode fibers made of fused silica are widely used for transmission of high power laser pulses. Bending of fibers creates mechanical stress inside the material. The bend stress of a fiber can be calculated from bend radius, geometrical fiber parameters and Young's Modulus of the fiber core material and reaches typically values of 220 MPa. A thermo-elastic model of Kusov et al. predicts a quadratic dependence of laser-induced damage threshold fluence with applied stress. In the present study, fiber preform material F300 (Heraeus) was loaded mechanically with pressures up to 220 MPa representing 20% of the pressure resistance of fused silica. Bulk laser-induced damage thresholds (LIDT) were evaluated using a longitudinal multimode Q-switched Nd:YAG laser (1064 nm) at a pulse duration of 12 ns with polarization states parallel and perpendicular to the stress direction. LIDT of fused silica samples of about 700 J/cm2 were found. LIDT did not show a dependence on mechanical pressure and polarization state which is a consequence of the small ratio of maximum applied stress (220 MPa) to Young's Modulus of fused silica (72.5 GPa). KW - Laser-induced damage threshold KW - LIDT KW - Nanosecond laser KW - Fused silica KW - Mechanical stress KW - Optical fiber PY - 2012 DO - https://doi.org/10.1016/j.apsusc.2012.01.049 SN - 0169-4332 SN - 1873-5584 VL - 258 IS - 23 SP - 9153 EP - 9156 PB - North-Holland CY - Amsterdam AN - OPUS4-26225 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rosenfeld, A. A1 - Rohloff, M. A1 - Höhm, S. A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Formation of laser-induced periodic surface structures on fused silica upon multiple parallel polarized double-femtosecond-laser-pulse irradiation sequences JF - Applied surface science N2 - The formation of laser-induced periodic surface structures (LIPSS) upon irradiation of fused silica with multiple irradiation sequences of parallel polarized Ti:sapphire femtosecond laser pulse pairs (160 fs pulse duration, 800 nm central wavelength) was studied experimentally. For that purpose, a Michelson interferometer was used to generate near-equal-energy double-pulse sequences allowing the temporal pulse delay between the parallel-polarized individual fs-laser pulses to be varied between 0 and 40 ps with ~0.2 ps temporal resolution. The surface morphologies of the irradiated surface areas were characterized by means of scanning electron and scanning force microscopy. In the sub-ps delay range a strong decrease of the LIPSS periods and the ablation crater depths with the double-pulse delay was observed indicating the importance of the laser-induced free-electron plasma in the conduction band of the solids for the formation of LIPSS. KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser ablation KW - Double-pulse experiments KW - Fused silica KW - Michelson interferometer PY - 2012 DO - https://doi.org/10.1016/j.apsusc.2011.09.076 SN - 0169-4332 SN - 1873-5584 VL - 258 IS - 23 SP - 9233 EP - 9236 PB - North-Holland CY - Amsterdam AN - OPUS4-26226 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Höhm, S. A1 - Rohloff, M. A1 - Rosenfeld, A. A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Dynamics of the formation of laser-induced periodic surface structures on dielectrics and semiconductors upon femtosecond laser pulse irradiation sequences JF - Applied physics A N2 - The formation of laser-induced periodic surface structures (LIPSS) upon irradiation of fused silica and silicon with multiple (NDPS) irradiation sequences consisting of linearly polarized femtosecond laser pulse pairs (pulse duration ~150 fs, central wavelength ~800 nm) is studied experimentally. Nearly equal-energy double-pulse sequences are generated allowing the temporal pulse delay Δt between the cross-polarized individual fs-laser pulses to be varied from -40 ps to +40 ps with a resolution of ~0.2 ps. The surface morphologies of the irradiated surface areas are characterized by means of scanning electron and scanning force microscopy. Particularly for dielectrics in the sub-ps delay range striking differences in the orientation and spatial characteristics of the LIPSS can be observed. For fused silica, a significant decrease of the LIPSS spatial periods from ~790 nm towards ~550 nm is demonstrated for delay changes of less than ~2 ps. In contrast, for silicon under similar irradiation conditions, the LIPSS periods remain constant (~760 nm) for delays up to 40 ps. The results prove the impact of laser-induced electrons in the conduction band of the solid and associated transient changes of the optical properties on fs-LIPSS formation. PY - 2013 DO - https://doi.org/10.1007/s00339-012-7184-z SN - 0947-8396 VL - 110 IS - 3 SP - 553 EP - 557 PB - Springer CY - Berlin AN - OPUS4-27787 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 - Krüger, Jörg A1 - Meja, P. A1 - Autric, M. A1 - Kautek, Wolfgang T1 - Femtosecond pulse laser ablation of anodic oxide coatings on aluminium alloys with on-line acoustic observation JF - Applied surface science N2 - The 125-fs laser ablation behaviour (800 nm) of aluminium and anodic oxide coatings on an AlMgSi1 alloy was investigated. The multi-pulse ablation threshold of aluminium at 1.2 J cm-2 was less than that of the oxides of 2–3 J cm-2. Aluminium exhibited a single pulse modification (melting) threshold of 0.3 J cm-2. These values derived from an evaluation of the crater geometry coincided with on-line acoustic measurements. The detected microphone voltage amplitude increased linearly with the laser fluence. The morphology of the ablation craters on aluminium indicated melt formation and displacement of a homogeneous melt phase due to the recoil action of the expanding metal vapour. The laser-processed ceramic oxide phases, on the other hand, showed a spongy resolidified melt layer, which denotes a collocated in-depth formation both of a melt and a gas phase. These phenomena are discussed in terms of the relative dominance of penetration depth of laser light and heat affected zones in the investigated materials with strongly varying optical and thermodynamical properties. KW - Laser ablation KW - Acoustic measurement KW - Microphone KW - Aluminium KW - Aluminium oxide PY - 2002 SN - 0169-4332 SN - 1873-5584 VL - 186 IS - 1-4 SP - 374 EP - 380 PB - North-Holland CY - Amsterdam AN - OPUS4-6324 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Baudach, Steffen A1 - Krüger, Jörg A1 - Kautek, Wolfgang A1 - Lenzner, Matthias T1 - Femtosecond laser ablation of silicon-modification thresholds and morphology JF - Applied physics A N2 - We investigated the initial modification and ablation of crystalline silicon with single and multiple Ti:sapphire laser pulses of 5 to 400 fs duration. In accordance with earlier established models, we found the phenomena amorphization, melting, re-crystallization, nucleated vaporization, and ablation to occur with increasing laser fluence down to the shortest pulse durations. We noticed new morphological features (bubbles) as well as familiar ones (ripples, columns). A nearly constant ablation threshold fluence on the order of 0.2 J/cm2 for all pulse durations and multiple-pulse irradiation was observed. For a duration of ,100 fs, significant incubation can be observed, whereas for 5 fs pulses, the ablation threshold does not depend on the pulse number within the experimental error. For micromachining of silicon, a pulse duration of less than 500 fs is not advantageous. PY - 2002 DO - https://doi.org/10.1007/s003390100893 SN - 0947-8396 VL - 74 IS - 1 SP - 19 EP - 25 PB - Springer CY - Berlin AN - OPUS4-6328 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jeschke, H.O. A1 - Garcia, M.E. A1 - Lenzner, Matthias A1 - Bonse, Jörn A1 - Krüger, Jörg A1 - Kautek, Wolfgang T1 - Laser ablation thresholds of silicon for different pulse durations: theory and experiment JF - Applied surface science N2 - The ultrafast laser ablation of silicon has been investigated experimentally and theoretically. The theoretical description is based on molecular dynamics (MD) simulations combined with a microscopic electronic model. We determine the thresholds of melting and ablation for two different pulse durations =20 and 500 fs. Experiments have been performed using 100 Ti:Sap-phire laser pulses per spot in air environment. The ablation thresholds were determined for pulses with a duration of 25 and 400 fs, respectively. Good agreement is obtained between theory and experiment. KW - Laser ablation KW - Pulse duration KW - Threshold of silicon PY - 2002 DO - https://doi.org/10.1016/S0169-4332(02)00458-0 SN - 0169-4332 SN - 1873-5584 VL - 197-198 SP - 839 EP - 844 PB - North-Holland CY - Amsterdam AN - OPUS4-6314 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - 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 - 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 - 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 - Kautek, Wolfgang A1 - Pentzien, Simone A1 - Rudolph, Pascale A1 - Krüger, Jörg A1 - König, E. T1 - Laser interaction with coated collagen und cellulose fibre composites: fundamentals of laser cleaning of ancient parchment manuscripts and paper JF - Applied surface science N2 - Laser cleaning of delicate biological composite materials such as ancient parchment manuscripts from the 15th and 16th century and printed paper from the 19th century is demonstrated with an ultraviolet excimer pulsed laser at 308 nm. Laser fluence levels must stay below the ablation and destruction threshold of the parchment or paper substrate, and have to surpass the threshold of the contaminant matter. Foreign layers to be removed must exhibit a higher optical density than the artifact substrates. Synthetic carbonaceous dirt modelled by water-soluble black crayons showed a characteristically weak featureless laser-induced plasma spectroscopy spectrum near the noise limit. It turned out that laser-induced plasma spectroscopy is of limited use in monitoring halting points (or etch-stops) because it relies on the destruction not only of the laterally inhomogenously distributed contaminant but also of pigment phases on a microscopically rough parchment substrate. Laser-induced fluorescence spectroscopy, however, promises to be a valuable non-destructive testing technique for etch-stop monitoring. KW - Laser KW - Parchment KW - Papery KW - Spectroscopy KW - Laser cleaning PY - 1998 SN - 0169-4332 SN - 1873-5584 VL - 127-129 SP - 746 EP - 754 PB - North-Holland CY - Amsterdam AN - OPUS4-11516 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lenzner, Matthias A1 - Krüger, Jörg A1 - Sartania, S. A1 - Cheng, Z. A1 - Spielmann, Ch. A1 - Mourou, G. A1 - Kautek, Wolfgang A1 - Krausz, F. T1 - Femtosecond Optical Breakdown in Dielectrics JF - Physical review letters N2 - We report measurements of the optical breakdown threshold and ablation depth in dielectrics with different band gaps for laser pulse durations ranging from 5 ps to 5 fs at a carrier wavelength of 780 nm. For tau <100 fs, the dominant channel for free electron generation is found to be either impact or multiphoton ionization (MPI) depending on the size of the band gap. The observed MPI rates are substantially lower than those predicted by the Keldysh theory. We demonstrate that sub-10-fs laser pulses open up the way to reversible nonperturbative nonlinear optics (at intensities greater than 1014 W/cm2 slightly below damage threshold) and to nanometer-precision laser ablation (slightly above threshold) in dielectric materials. PY - 1998 SN - 0031-9007 SN - 1079-7114 VL - 80 IS - 18 SP - 4076 EP - 4079 PB - American Physical Society CY - Ridge, NY AN - OPUS4-11518 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 -