Filtern
Dokumenttyp
- Zeitschriftenartikel (52)
- Vortrag (34)
- Beitrag zu einem Tagungsband (9)
- Buchkapitel (5)
- Posterpräsentation (4)
- Monografie (1)
- Video (1)
Schlagworte
- Laser-induced periodic surface structures (LIPSS) (55)
- Surface functionalization (27)
- Femtosecond laser (21)
- Laser processing (13)
- Femtosecond laser ablation (11)
- Applications (10)
- Laser-induced periodic surface structures, LIPSS (10)
- Radiation protection (9)
- Laser ablation (8)
- Nanostructures (8)
- Laser-induced X-ray emission (7)
- Microstructures (7)
- Oxidation (7)
- Tribology (6)
- Femtosecond laser processing (5)
- Capillary waves (4)
- Electromagnetic scattering (4)
- Friction (4)
- Silicon (4)
- Ultrashort laser material interaction (4)
- Wear (4)
- Chalcopyrite (3)
- Free electron laser (3)
- Hard X-ray photoelectron spectroscopy (HAXPES) (3)
- Industrial applications (3)
- Time-resolved scattering (3)
- Ultrafast laser processing (3)
- Ultrashort laser pulses (3)
- Ultrashort pulsed laser (3)
- Anodization (2)
- Biofilms (2)
- Chemical analysis (2)
- Cribellate spiders (2)
- Direct laser interference patterning (DLIP) (2)
- Finite-difference time-domain calculations (2)
- Laser-induced forward transfer (2)
- Laser-induced oxide layer (2)
- Laser-induced x-ray emission (2)
- Modelling (2)
- Niobium (2)
- Oberflächenfunktionalisierung (2)
- Polycarbonate (2)
- Pump-probe experiments (2)
- Secondary hazard (2)
- Self-organization (2)
- Spectroscopic imaging ellipsometry (2)
- Steel (2)
- Surface modification (2)
- Ti6Al4V alloy (2)
- Time-of-flight secondary ion mass spectrometry (ToF-SIMS) (2)
- Titanium (2)
- Ultra-short pulse laser processing (2)
- Ultrashort laser processing (2)
- Ultrashort pulse laser processing (2)
- ASTM (1)
- Additive (1)
- Additives (1)
- Amorphization (1)
- Analysis (1)
- Antiadhesive surfaces (1)
- Antibacterial surfaces (1)
- Antibakterielle Oberflächen (1)
- Antimicrobial (1)
- Atomic force microscopy (1)
- Bacteria (1)
- Bacteria-repellent surfaces (1)
- Bacterial adhesion (1)
- Bacterial adhesion tests (1)
- Bessel-Strahlen (1)
- Biofilm (1)
- Biofilm formation (1)
- Biofilm growth (1)
- Biofilme (1)
- Bioinspiration (1)
- Biomimetic (1)
- Biomimetic surfaces (1)
- Bionic materials (1)
- Bone screws (1)
- Bulk metallic glasses (1)
- Bulk temperature (1)
- Calamistrum (1)
- Carbon fibers (1)
- Cell appendages (1)
- Cell-repellent surfaces (1)
- Ceramic matrix composites (1)
- Chemical analyses (1)
- Crystallization (1)
- Cu(In,Ga)Se2 (1)
- D7755-11 (1)
- Dentistry (1)
- Direct laser interference patterning (1)
- Editorial (1)
- Electrochemical treatment (1)
- Electromagnetic radiation (1)
- Electromagnetic theories (1)
- Electron backscattering diffraction (EBSD) (1)
- Electron microscopy (1)
- Electrospinning (1)
- European funding strategies (1)
- F pili (1)
- Femtosecond (1)
- Femtosecond laser patterning (1)
- Femtosecond laser-processing (1)
- Femtosekunden-Laserablation (1)
- Fluid-flow (1)
- Force distance curve (1)
- Free electron laser (FEL) (1)
- Fs-Laser (1)
- Fs-laser patterning (1)
- Functional properties (1)
- Glasses (1)
- Glow-discharge optical emission spectroscopy (1)
- Grain orientation (1)
- Grating (1)
- Heat diffusion (1)
- Hexagonally-arranged nano-protrusions (1)
- Hierarchical structures (1)
- Hydrodynamics (1)
- Implant material (1)
- Industrial application (1)
- LIFT (1)
- LIPSS (1)
- Large area structuring (1)
- Laser (1)
- Laser Machining (1)
- Laser damage (1)
- Laser nanostructuring (1)
- Laser technology (1)
- Laser-Materialbearbeitung (1)
- Laser-induced Periodic Surface Structures (LIPSS) (1)
- Laser-induced amorphization (1)
- Laser-induced micro- and nanostructures (1)
- Laser-induced nanostructures (1)
- Laser-induced periodic surface strctures (LIPSS) (1)
- Laser-induced periodic surface structures (1)
- Laser-induzierte periodische Oberflächen-Nanostrukturen (1)
- Laser-induzierte periodische Oberflächenstrukturen (1)
- Laser-modified surface (1)
- Laserschutz (1)
- Light concentration (1)
- Literature survey (1)
- Materialbearbeitung (1)
- Matter reorganization (1)
- Matter reorganization theories (1)
- Medical implants (1)
- Melting (1)
- Metals (1)
- Micro solar cell (1)
- Micro solar cells (1)
- Micro-concentrator solar cell (1)
- Microbial adhesions (1)
- Mikrostrukturen (1)
- Nanofibers (1)
- Nanosecond laser (1)
- Nanosecond laser irradiation (1)
- Nanostrcutures (1)
- Nanostructuring (1)
- Nanostrukturen (1)
- Native oxide layer (1)
- Nonlinear lithography (1)
- Oberflächenmodifikation (1)
- Ophthalmology (1)
- Optical scattering (1)
- Phase mask (1)
- Phase-contrast microscopy (1)
- Photovoltaics (1)
- Polyethylene (1)
- Polyethylene terephthalate (1)
- Protection housing (1)
- Pulse Laser (1)
- Pump-probe (1)
- Quarzglas (1)
- Reactive oxygen species (1)
- Reibung (1)
- Reibungsreduktion (1)
- Röntgenemission (1)
- Saphir (1)
- Second-generation high temperature superconductor technology (1)
- Sekundärstrahlung (1)
- Sliding (1)
- Superconductivity (1)
- Surface (1)
- Surface chemistry (1)
- Surface engineering (1)
- Surface oxidation (1)
- Surface plasmon polaritons (1)
- Surface processing (1)
- Surface structures (1)
- Surface superconductivity (1)
- Surface texture (1)
- Theoretical modelling (1)
- Thin films (1)
- Ti6Al4V alloys (1)
- Time-offlight secondary ion mass spectrometry (ToF-SIMS) (1)
- Time-resolved analysis (1)
- Time-resolved coherent scattering (1)
- Titanium alloy (1)
- Titanium alloys (1)
- ToF-SIMS (1)
- Transmission electron microscopy (1)
- Tribologie (1)
- Ultrafast scattering (1)
- Ultrakurze Laserpulse (1)
- Ultrakurzpuls-Laser (1)
- Ultrakurzpuls-Laserbearbeitung (1)
- Ultrashort (1)
- Ultrashort lasers (1)
- Verschleiß (1)
- Verschleißreduktion (1)
- Wetting (1)
- X-ray (1)
- X-ray emission (1)
- X-ray emission hazards (1)
- X-ray energies (1)
- X-ray photoelectron spectroscopy (1)
- X-ray spectrum (1)
- XUV scattering (1)
Organisationseinheit der BAM
- 6.2 Material- und Oberflächentechnologien (106) (entfernen)
Paper des Monats
- ja (3)
Time-resolved phase-contrast microscopy is employed to visualize spatio-temporal thermal transients induced by tight focusing of a single Ti:sapphire fs-laser pulse into a solid dielectric sample. This method relies on the coupling of the refractive index change and the sample temperature through the thermo-optic coefficient dn/dT. The thermal transients are studied on a timescale ranging from 10 ns up to 0.1 ms after laser excitation. Beyond providing direct insights into the laser–matter interaction, analyzing the results obtained also enables quantifying the local thermal diffusivity of the sample on a micrometer scale. Studies conducted in different solid dielectrics, namely amorphous fused silica (a-SiO2), a commercial borosilicate glass (BO33, Schott), and a custom alkaline earth silicate glass (NaSi66), illustrate the applicability of this approach to the investigation of various glassy materials.
During the past few years significantly increasing research activities in the field of laser-induced periodic surface structures (LIPSS, ripples) have been reported since the generation of LIPSS in a single-step process provides a simple way of surface nanostructuring towards a control of optical, mechanical or chemical surface properties. In this contribution the current research state in this field is reviewed. The formation of LIPSS upon irradiation of metals, semiconductors and dielectrics by multiple linearly polarized Ti:sapphire fs-laser pulses (30-150 fs) is studied experimentally and theoretically. Different types of LIPSS with periods even below 100 nm can be generated. Their dynamics and formation mechanisms are analyzed and identified in ultrafast optical experiments. Complementing theoretical calculations of the laser-induced carrier dynamics address transient changes of the optical properties of the irradiated materials and reveal the importance of surface plasmon polaritons in the early stage of LIPSS formation. Various applications of these nanostructures are outlined.
A laser-based bottom-up technique for the fabrication of Cu(In,Ga)Se2 (CIGSe) micro solar cells is presented.
We use femtosecond laser-induced forward transfer (LIFT) to transport a metallic precursor composed of copper, indium, and gallium onto a molybdenum back contact layer on a glass substrate. A CIGSe absorber forms by subsequent selenization. An array of micro absorbers with defined spacing is fabricated to solar cells and characterized under concentrated light illumination. The solar cell array exhibited a conversion efficiency of 1.4‰ at 1 sun as well as a significant efficiency enhancement of 68% rel. under 20-fold concentration. This work demonstrates the possibility of directly grown micrometer-sized solar cells based on chalcogenide absorber layers, enabling effective material usage.
Light concentration opens up the path to enhanced material efficiency of solar cells via increased conversion efficiency and decreased material requirement. For true material saving, a fabrication method allowing local growth of high quality absorber material is essential. We present two scalable fs-laser based approaches for bottom-up growth of Cu(In,Ga)Se2 micro islands utilizing either site-controlled assembly of In(,Ga) droplets on laser-patterned substrates during physical vapor deposition, or laser-induced forward transfer of (Cu,In,Ga) layers for local precursor arrangement. The Cu(In,Ga)Se2 absorbers formed after selenization can deliver working solar devices showing efficiency enhancement under light concentration.
The formation and properties of laser-induced periodic surface structures (LIPSS) were investigated on carbon fibers under irradiation of fs-laser pulses characterized by a pulse duration τ = 300 fs and a laser wavelength λ = 1025 nm. The LIPSS were fabricated in an air environment at normal incidence with different values of the laser peak fluence and number of pulses per spot. The morphology of the generated structures was characterized by using scanning electron microscopy, atomic force microscopy and Fast-Fourier transform analyses. Moreover, the material structure and the surface chemistry of the carbon fibers before and after laser irradiation was analyzed by micro Raman spectroscopy and X-ray photoelectron spectroscopy. Large areas in the cm2 range of carbon fiber arrangements were successfully processed with homogenously distributed high- and low-spatial frequency LIPSS. Beyond those distinct nanostructures, hybrid structures were realized for the very first time by a superposition of both types of LIPSS in a two-step process. The findings facilitate the fabrication of tailored LIPSS-based surface structures on carbon fibers that could be of particular interest for e.g. fiber reinforced polymers and concretes.
Laser texturing is an emerging technology for generating surface functionalities on basis of optical, mechanical, or chemical properties. Taking benefit of laser sources with ultrashort (fs) pulse durations features outstanding precision of machining and negligible rims or burrs surrounding the laser-irradiation zone. Consequently, additional mechanical or chemical post-processing steps are usually not required for fs-laser surface texturing (fs-LST). This work aimed to provide a bridge between research in the field of tribology and laser materials processing. The paper reviews the current state-of-the-art in fs-LST, with a focus on the tribological performance (friction and wear) of specific self-organized surface structures (so-called ripples, grooves, and spikes) on steel and titanium alloys. On the titanium alloy, specific sickle-shaped hybrid micro-nanostructures were also observed and tribologically tested. Care is taken to identify accompanying effects affecting the materials hardness, superficial oxidation, nano- and microscale topographies, and the role of additives contained in lubricants, such as commercial engine oil.
In laser machining with ultrashort laser pulses unwanted X-ray radiation in the keV range can be generated when a critical laser intensity is exceeded. Even if the emitted X-ray dose per pulse is low, high laser repetition rates can lead to an accumulation of X-ray doses beyond exposure safety limits. For 925 fs pulse duration at a center wavelength of 1030 nm, the X-ray emission was investigated up to an intensity of 2.6 × 10^14 W/cm2. The experiments were performed in air with a thin disk laser at a repetition rate of 400 kHz. X-ray spectra and doses were measured for various planar target materials covering a wide range of the periodic table from aluminum to tungsten. Without radiation shielding, the measured radiation doses at this high repetition rate clearly exceed the regulatory limits. Estimations for an adequate radiation shielding are provided.
Lasermaterialbearbeitung ist eine sich schnell entwickelnde Technologie, um eine Vielzahl von Oberflächenfunktionalitäten auf Basis optischer, mechanischer oder chemischer Eigenschaften zu realisieren. Die Verwendung ultrakurzer Laserimpulse mit Dauern im Femtosekundenbereich ermöglicht dabei neben einer herausragenden Bearbeitungs-präzision auch die selbstorganisierte Erzeugung verschiedener charakteristischer Ober-flächenstrukturen mit Größenskalen im Mikrometer- bis hinunter in den sub-100-nm-Bereich, z.B. sogenannte Ripples („Laser-Induced Periodic Surface Structures“, LIPSS), Grooves, oder Spikes.
In dem Vortrag wird ein Überblick über die in den vergangenen Jahren in Zusammenarbeit mit dem BAM Fachbereich 6.3 durchgeführten tribologischen Experimente gegeben. Besonderes Augenmerk liegt dabei auf den tribologischen Eigenschaften (Reibung und Verschleiß) der unterschiedlichen Femtosekunden-Laser-generierten Oberflächen-morphologien auf gängigen Metallen (z.B. Stahl, Titan). Einflüsse durch die Veränderungen der Härte des Werkstoffs infolge Laser-induzierter Oxidation, der Dicke und Struktur der Oxidschicht, und die Wirksamkeit unterschiedlicher Schmiermittel (z.B. additiviertes Motoröl) werden diskutiert.
In this contribution the mechanisms of formation and current applications of LIPSS are reviewed, including the colorization of technical surfaces, the control of surface wetting properties, the mimicry of the natural texture of animal integuments, the tailoring of surface colonization by bacterial biofilms, and the improvement of the tribological performance of nanostructured metal surfaces.
Laser-induced periodic surface structures (LIPSS, ripples) are a universal phenomenon that can be observed on almost any material after the irradiation by linearly polarized laser beams, particularly when using ultrashort laser pulses with durations in the femtosecond to picosecond range.
During the past few years significantly increasing research activities have been reported in the field of LIPSS, since their generation in a single-step process provides a simple way of nanostructuring and surface functionalization towards the control of optical, mechanical, biological, or chemical surface properties. In this contribution the mechanisms of formation and current applications of LIPSS are reviewed, including the colorization of technical surfaces, the control of surface wetting properties, the mimicry of the natural texture of animal integuments, the tailoring of surface colonization by bacterial biofilms, the advancement of medical pacemakers, and the improvement of the tribological performance of nanostructured metal surfaces.