High-quality surface treatment using GHz burst mode with tunable ultrashort pulses

Metzner, Daniel; Lickschat, Peter; Weißmantel, Steffen

doi:10.1016/j.apsusc.2020.147270

Cited by 32 publications

(20 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Of course, more detailed studies need to be performed to gain a full view on this topic. Finally, it can be seen from the reviewed and summarized studies that the surface roughness shows a minimum for a low number of burst pulses (corresponding to short burst time spans), which can be significantly lower compared to single pulses [ 21 , 23 , 24 , 64 , 124 , 135 , 141 , 142 , 143 , 144 ]. For longer time spans and a higher number of pulses, heat accumulation highly dominates laser processing, leading to higher energy specific volumes as well as significantly higher roughness, which is also the case for longer pulses in the ns and µs regime due to the emerging occurrence of melting.…”

Section: Physics Of Ultra-short Burst Pulse Ablation Of Metalsmentioning

confidence: 99%

“…Thus, the available energy per pulse is often much higher than the energy actually needed for single pulse ablation. In order to attain the highest possible ablated volume for a given amount of energy, the energy can be distributed among pulses within a pulse package, a so-called pulse burst consisting of a minimum of two pulses and up to several hundred or thousand pulses [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. Each of these burst packages then carries a sufficiently high amount of energy that can be used for laser machining, while the total energy of all pulses together is close to the maximum available pulse energy of the laser.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Review on Experimental and Theoretical Investigations of Ultra-Short Pulsed Laser Ablation of Metals with Burst Pulses

et al. 2021

View full text Add to dashboard Cite

Laser processing with ultra-short double pulses has gained attraction since the beginning of the 2000s. In the last decade, pulse bursts consisting of multiple pulses with a delay of several 10 ns and less found their way into the area of micromachining of metals, opening up completely new process regimes and allowing an increase in the structuring rates and surface quality of machined samples. Several physical effects such as shielding or re-deposition of material have led to a new understanding of the related machining strategies and processing regimes. Results of both experimental and numerical investigations are placed into context for different time scales during laser processing. This review is dedicated to the fundamental physical phenomena taking place during burst processing and their respective effects on machining results of metals in the ultra-short pulse regime for delays ranging from several 100 fs to several microseconds. Furthermore, technical applications based on these effects are reviewed.

show abstract

Section: Physics Of Ultra-short Burst Pulse Ablation Of Metalsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Review on Experimental and Theoretical Investigations of Ultra-Short Pulsed Laser Ablation of Metals with Burst Pulses

et al. 2021

View full text Add to dashboard Cite

show abstract

“…The minimal surface roughness achieved after a single scan over the surface was ~250 nm. It is known that for metals, scanning the surface multiple times increases the smoothness of the surface [ 39 , 40 ]. Therefore, the surface roughness was also measured when performing several scans (a change in the scanning angle by 90

is produced after each pass).…”

Section: Resultsmentioning

confidence: 99%

Micromachining of Transparent Biocompatible Polymers Applied in Medicine Using Bursts of Femtosecond Laser Pulses

et al. 2020

View full text Add to dashboard Cite

Biocompatible polymers are used for many different purposes (catheters, artificial heart components, dentistry products, etc.). An important field for biocompatible polymers is the production of vision implants known as intraocular lenses or custom-shape contact lenses. Typically, curved surfaces are manufactured by mechanical means such as milling, turning or lathe cutting. The 2.5 D objects/surfaces can also be manufactured by means of laser micromachining; however, due to the nature of light–matter interaction, it is difficult to produce a surface finish with surface roughness values lower than ~1 µm Ra. Therefore, laser micromachining alone can’t produce the final parts with optical-grade quality. Laser machined surfaces may be polished via mechanical methods; however, the process may take up to several days, which makes the production of implants economically challenging. The aim of this study is the investigation of the polishing capabilities of rough (~1 µm Ra) hydrophilic acrylic surfaces using bursts of femtosecond laser pulses. By changing different laser parameters, it was possible to find a regime where the surface roughness can be minimized to 18 nm Ra, while the polishing of the entire part takes a matter of seconds. The produced surface demonstrates a transparent appearance and the process shows great promise towards commercial fabrication of low surface roughness custom-shape optics.

show abstract

“…few picoseconds 7,8 to some microseconds [9][10][11][12] . BM processing has been found to be beneficial for many applications like e.g.…”

mentioning

confidence: 99%

“…BM processing has been found to be beneficial for many applications like e.g. surface structuring [13][14][15][16] , multi-photon absorption enhancement 17 , and laser milling 9,10,18 . Despite the recent advances, there are still open questions on the physical mechanisms that come into play and influence the laser-matter interaction, when bursts of ultrashort pulses are used instead of single pulses, the latter known as normal pulse mode (NPM) irradiation.…”

mentioning

confidence: 99%

Laser ablation of silicon with THz bursts of femtosecond pulses: an experimental and theoretical investigation

Gaudiuso¹,

Terekhin²,

Volpe³

et al. 2021

Preprint

View full text Add to dashboard Cite

In this work, we performed an experimental investigation supported by a theoretical analysis, to improve knowledge on the laser ablation of silicon with THz bursts of femtosecond laser pulses. Laser ablated craters have been created using 200 fs pulses at a wavelength of 1030 nm on silicon samples systematically varying the burst features and comparing to the Normal Pulse Mode (NPM). Using bursts in general allowed reducing the thermal load to the material, however, at the expense of the ablation rate. The higher the number of pulses in the bursts and the lower the intra-burst frequency, the lower is the specific ablation rate. However, bursts at 2 THz led to a higher specific ablation rate compared to NPM, in a narrow window of parameters. Theoretical investigations based on the numerical solution of the density-dependent two temperature model revealed that lower lattice temperatures are reached with more pulses and lower intra-burst frequencies, thus supporting the experimental evidence of the lower thermal load in Burst Mode (BM). This is ascribed to the weaker transient drop of reflectivity, which suggests that with bursts less energy is transferred from the laser to the material. This also explains the trends of the specific ablation rates. Moreover, we found that two-photon absorption plays a fundamental role during BM processing in the THz frequency range.

show abstract

High-quality surface treatment using GHz burst mode with tunable ultrashort pulses

Cited by 32 publications

References 19 publications

Review on Experimental and Theoretical Investigations of Ultra-Short Pulsed Laser Ablation of Metals with Burst Pulses

Review on Experimental and Theoretical Investigations of Ultra-Short Pulsed Laser Ablation of Metals with Burst Pulses

Micromachining of Transparent Biocompatible Polymers Applied in Medicine Using Bursts of Femtosecond Laser Pulses

Laser ablation of silicon with THz bursts of femtosecond pulses: an experimental and theoretical investigation

Contact Info

Product

Resources

About