Process optimization in high-average-power ultrashort pulse laser microfabrication: how laser process parameters influence efficiency, throughput and quality

Schille, Joerg; Schneider, Lutz; Loeschner, Udo

doi:10.1007/s00339-015-9352-4

Cited by 74 publications

(39 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is the dose equivalent at a depth of 10 mm in a 30-cm diameter sphere of unit density tissue (ICRU-sphere, International Commission on Radiation Units and Measurements). The ICRU-sphere is a sphere with a density of 1 g/ cm 3 and a mass composition of 76.2% oxygen, 11.1% carbon, 10.1% hydrogen, and 2.6% nitrogen. The directional dose equivalent H′ (0.07, Ω) is the operational quantity for the determination of the dose to the human skin and is measured at a depth of 0.07 mm in the ICRU-sphere.…”

Section: X-ray Dose Measurementsmentioning

confidence: 99%

See 1 more Smart Citation

X-ray emission as a potential hazard during ultrashort pulse laser material processing

et al. 2018

View full text Add to dashboard Cite

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/cm 2 . 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.

show abstract

Section: X-ray Dose Measurementsmentioning

confidence: 99%

“…For that different ultra-fast laser processing strategies are employed. For an optimum laser ablation efficiency along with high machining precision, fluences of about ten times the ablation threshold are used [2][3][4]. An optimum processing window around 1 J/cm 2 was found for steel.…”

Section: Introductionmentioning

confidence: 99%

X-ray emission as a potential hazard during ultrashort pulse laser material processing

et al. 2018

View full text Add to dashboard Cite

show abstract

“…On the other hand, by contrast, a few studies identified insignificant or no increase of metal ablation for double-pulse processing, as stated for aluminum [32], copper [19], and titanium [21]. Later studies have shown experimentally and by modeling that splitting the pulse energy was a way to be closer to the optimal regime for laser ablation with increased efficiency, without clear evidence in benefits of burst regime in laser ablation [33,34]. However, for pulse-train processing, the relevant literature identified up to four different characteristic ablation regimes that are distinguished based on their inter-pulse delay.…”

Section: Introductionmentioning

confidence: 82%

“…Moreover, thanks to recent progress in developing high-average power ultrashort-pulse lasers with tens of megahertz repetition frequencies, machining throughput can considerably be enhanced [1,2], which has a great potential to substitute conventional micromachining technologies in industrial mass production. However, initial studies investigating high-PRF ultrashort-pulse processing identified that the removal rate decreased when operating with pulses of several hundred kilohertz to megahertz pulse repetitions [3,4].…”

Section: Introductionmentioning

confidence: 99%

Experimental study on double-pulse laser ablation of steel upon multiple parallel-polarized ultrashort-pulse irradiations

et al. 2016

Self Cite

View full text Add to dashboard Cite

In this paper, double-pulse laser processing is experimentally studied with the aim to explore the influence of ultrashort pulses with very short time intervals on ablation efficiency and quality. For this, sequences of 50 double pulses of varied energy and inter-pulse delay, as adjusted between 400 fs and 18 ns by splitting the laser beam into two optical paths of different length, were irradiated to technical-grade stainless steel. The depth and the volume of the craters produced were measured in order to evaluate the efficiency of the ablation process; the crater quality was analyzed by SEM micrographs. The results obtained were compared with craters produced with sequences of 50 single pulses and energies equal to the double pulse. It is demonstrated that double-pulse processing cannot exceed the ablation efficiency of single pulses of optimal fluence, but the ablation crater surface formed smoother if inter-pulse delay was in the range between 10 ns and 18 ns. In addition, the influence of pulse duration and energy distribution between the individual pulses of the double pulse on ablation was studied. For very short inter-pulse delay, no significant effect of energy variation within the double pulse on removal rate was found, indicating that the double pulse acts as a big single pulse of equal energy. Further, the higher removal efficiency was achieved when double-pulse processing using femtosecond pulses instead of picosecond pulses.

show abstract

“…Therewith, the ultrafast laser beam movement is essential for the efficient upscaling of the processing rates when using such unprecedented high laser powers. This is due to the fact that only a few micro joules optical energy at low fluence is needed for most-efficient material removal [19][20][21]. In consequence, the optimum method for upscaling the processing rate will be increasing the pulse repetition frequency instead of using higher pulse energies.…”

Section: High-rate Laser Processing Technologymentioning

confidence: 99%

High-Rate Laser Surface Texturing for Advanced Tribological Functionality

et al. 2020

Self Cite

View full text Add to dashboard Cite

This article features with the enhancement of the static coefficient of friction by laser texturing the contact surfaces of tribological systems tested under dry friction conditions. The high-rate laser technology was applied for surface texturing at unprecedented processing rates, namely using powerful ultrashort pulses lasers in combination with ultrafast polygon-mirror based scan systems. The laser textured surfaces were analyzed by ion beam slope cutting and Raman measurements, showing a crystallographic disordering of the produced microscopic surface features. The laser induced self-organizing periodic surface structures as well as deterministic surface textures were tested regarding their tribological behavior. The highest static coefficient of friction was found of µ20 = 0.68 for a laser textured cross pattern that is 126% higher than for a fine grinded reference contact system. The line pattern was textured on a shaft-hub connection where the static coefficient of friction increased up to 75% that demonstrates the high potential of the technology for real-world applications.

show abstract

Process optimization in high-average-power ultrashort pulse laser microfabrication: how laser process parameters influence efficiency, throughput and quality

Cited by 74 publications

References 28 publications

X-ray emission as a potential hazard during ultrashort pulse laser material processing

X-ray emission as a potential hazard during ultrashort pulse laser material processing

Experimental study on double-pulse laser ablation of steel upon multiple parallel-polarized ultrashort-pulse irradiations

High-Rate Laser Surface Texturing for Advanced Tribological Functionality

Contact Info

Product

Resources

About