3D printing of common metals is highly challenging because are generally solid at room conditions. Copper and gold pillars manufactured with a resolution below 5 μm height up to 2 mm, using laser-induced forward transfer create eject liquid metal droplets. The solidified drop's shape crucial for discussed as function the laser energy.

Optical solid state deflectors rely on the electro-optical or acousto-optic effect. These Electro-Optical Deflectors (EODs) and Acousto-Optical (AODs) do not contain moving parts therefore exhibit high deflection velocities are free of drawbacks associated with mechanical scanners. A description principles operation EODs AODs is presented. In addition, characteristics, properties (dis)advantages AODs, when compared to mirror based deflectors, discussed. Deflection angles, speed accuracy...

The combination of a dual-scale (nano and micro) roughness with an inherent low-surface energy coating material is essential factor for the development superhydrophobic surfaces. Ultrashort pulse laser (USPL) machining/structuring promising technique obtaining roughness. Sheets stainless steel (AISI 304 L SS) Ti-6Al-4V alloys were laser-machined ultraviolet pulses 6.7 ps, different numbers per irradiated area. surface samples was reduced via application layer perfluorinated...

The finite-difference time-domain (FDTD) method is used to study the inhomogeneous absorption of linearly polarized laser radiation below a rough surface. results are first analyzed in frequency domain and compared efficacy factor theory Sipe coworkers. Both approaches show that absorbed energy shows periodic nature, not only direction orthogonal polarization, but also parallel it. It shown periodicity always close wavelength for perpendicular direction. In direction, about...

Leidenfrost ratchets are structures with the ability of transporting liquid droplets when heated over critical temperature. Once this temperature is reached, droplet levitates surface and moves in direction marked by slope ratchet at terminal velocities around 10 cm/s. Here we provide new experiments micron-sized ratchets, which have been produced picosecond pulse laser ablation. In following work, use a simple method to measure thrust driving capillary size micro-ratchets. The mechanism...

Droplets are able to levitate when deposited over a hot surface exceeding critical temperature. This is known as the Leidenfrost effect. phenomenon occurs heated above so-called point (LFP), which vapor film between droplet and droplet. Such temperature depends on several factors. One of most studied parameters has been roughness. Almost all experimental studies in literature have concluded that LFP increases with According these results, it seems roughness detrimental for stability film. In...

This paper aims at contributing to the study of laser-induced periodic surface structures (LIPSS) and description their tribological properties in order facilitate knowledge for contact mechanical applications. To obtain laser parameters LIPSS formation, we propose execute two D2-Experiments. For transfer results from static experiments areas discrete accumulation fluences. Areas covered by homogeneously distributed were machined. Friction force these was measured using a tribometer ball on...

A model predicting the formation of laser-induced periodic surface structures (LIPSSs) is presented. That is, finite-difference time domain method used to study interaction electromagnetic fields with rough surfaces. In this approach, modified by “ablation after each laser pulse,” according absorbed energy profile, in order account for inter-pulse feedback mechanisms. LIPSSs a periodicity significantly smaller than wavelength are found “grow” either parallel or orthogonal polarization. The...

Slender, out-of-plane metal microdevices are made in a new spatial domain, by using laser-induced forward transfer (LIFT) of metals. Here, thermocouple with thickness 10 µm and height 250 µm, consisting platinum gold pillars is demonstrated. Multimaterial LIFT enables manufacturing the micrometer to millimeter range, i.e., between lithography other 3D printing technologies. As service our authors readers, this journal provides supporting information supplied authors. Such materials peer...

The absorptivity of a material is major uncertainty in numerical simulations laser welding and additive manufacturing, its value often calibrated through trial-and-error exercises. This adversely affects the capability when predicting process behaviour can eventually hinder exploitation fully digitised manufacturing processes, which goal "industry 4.0". In present work, an enhanced absorption model that takes into account effects characteristics, incident angle, surface temperature,...

Laser beam shaping offers remarkable possibilities to control and optimise process stability tailor material properties structure in laser-based welding additive manufacturing. However, little is known about the influence of laser on complex melt-pool behaviour, solidified melt-track bead profile microstructural grain morphology processing. A simulation-based approach utilised present work study effects intensity angle incidence behaviour conduction-mode melting stainless steel 316L plates....

Modeling the thermal and fluid flow fields in laser-based directed energy deposition (DED-LB) is crucial for understanding process behavior ensuring part quality. However, existing models often fail to accurately predict these due simplifying assumptions, particularly regarding powder particle-induced attenuation laser power density distribution, variable material properties parameters. The present work introduces a high-fidelity multi-phase thermal-fluid model driven by combination of...

Laser-induced forward transfer (LIFT) allows for high-resolution three-dimensional printing of e.g. small metal droplets, which inkjet is not an option. Although the technique almost 30 years old, a detailed understanding its physics has been lacking. The authors observe and explain high-speed mechanisms behind ejection pure microdrops during LIFT, further parameter optimization particular job.

A combined approach of laser-induced forward transfer (LIFT) and chemical etching pure metal films is studied to fabricate complex, free-standing, 3-dimensional gold structures on the few micron scale. picosecond pulsed laser source with 515 nm central wavelength used deposit droplets copper in a sequential fashion. After transfer, ferric chloride completely removes mechanical Cu support leaving final free-standing structure. Unprecedented feature sizes smaller than 10 μm are achieved...

In Laser-based Directed Energy Deposition (L-DED) the laser-induced spatial and temporal thermal cycles strongly determine microstructure of deposited layers. The effect three different laser intensity profiles (beam shapes) on shape melt pool resulting was studied. To this end, gradients growth rates, derived from measured emissions, are compared to characteristics in tracks. These obtained using Electron Back Scatter Diffraction (EBSD). It found that beam affects morphology. Therefore it...

Besides the social and personal benefits of a rehabilitation robot, direct cost-savings other (indirect) economic benefits, or effectiveness, are major importance to party who pays for (or reimburses) robot. This paper gives an overview these and, on larger scale, assistive robotic manipulator (arm)

Three-dimensional bulk modification of dielectric materials by multiphoton absorption laser pulses is a well-established technology.The use to machine silicon has been investigated number authors using femtosecond sources.However, no modifications confined in silicon, induced absorption, have reported so far.Based on results from numerical simulations, we employed an erbium-doped fiber operating at relatively long pulse duration 3.5 nanoseconds and wavelength 1549 nm for this process.We...

Ablation of bulk polycrystalline zinc in air is performed with single and multiple picosecond laser pulses at a wavelength 1030 nm. The relationships between the characteristics ablated craters processing parameters are analyzed. Morphological changes characterized by means scanning electron microscopy confocal microscopy. Chemical compositions both treated untreated surfaces quantified X-ray photoelectron spectroscopy. A comparative analysis on determination ablation threshold using three...