Drilling rate of five metals with picosecond laser pulses at 355, 532, and 1064 nm

Abstract

Experimental results on picosecond laser processing of aluminum, nickel, stainless steel, molybdenum, and tungsten are described. Hole drilling is employed for comparative analysis of processing rates in an air environment. Drilling rates are measured over a wide range of laser fluences (0.05-20 J/cm 2 ). Experiments with picosecond pulses at 355 nm are carried out for all five metals and in addition at 532 nm, and 1064 nm for nickel. A comparison of drilling rate with 6-ps and 6-ns pulses at 355 nm is performed. The dependence of drilling rate on laser fluence measured with picosecond pulses demonstrates two logarithmic regimes for all five metals. To determine the transition from one regime to another, a critical fluence is measured and correlated with the thermal properties of the metals. The logarithmic regime at high-fluence range with UV picosecond pulses is reported for the first time. The energy efficiency of material removal for the different regimes is evaluated. The results demonstrate that UV picosecond pulses can provide comparable quality and higher processing rate compared with literature data on ablation with near-IR femtosecond lasers. A significant contribution of two-photon absorption to the ablation process is suggested to explain high processing rate with powerful UV picosecond pulses.

Surface ablation and threshold determination of AlCu4SiMg aluminum alloy in picosecond pulsed laser micromachining

“…Le Drogoff et al [31] determined the ablation threshold of aluminum thin films for plasma formation to be approximately 0.1 J cm À2 by subpicosecond laser pulses. Le Harzic et al [32] and Spiro et al [18] carried out the experimental studies on micromachining pure aluminum by ultrafast laser pulses to obtain the ablation thresholds at low energy-density and the values were calculated to be about 0.12 and 0.46 J cm À2 , respectively. The numerical values are not the same, and they also cannot satisfy the demand of various kinds of aluminum alloy in ultrafast laser micromachining.…”

“…So far, ultrafast pulsed laser ablation thresholds of several typical materials have been investigated. In the aspect of metal materials, many studies have focused on stainless steel, gold, silver, copper, platinum, tungsten, chromium, niobium, molybdenum, nickel, nickel-base alloy, titanium, and titanium alloy [13][14][15][16][17][18][19][20][21][22][23][24]; however, ablation mechanisms and thresholds of aluminum and its alloys have not been extensively investigated, and the available few studies on aluminum and its alloys generally focused on the micro-nanostructure characteristics of ultrafast laser processing, laser-induced breakdown spectroscopy, and laser shock peening on pure aluminum or aluminum alloy. Jorgensen et al [25] formed the nanoparticles using femtosecond laser ablation in intermetallic aluminum-nickel (NiAl) alloy.…”

Comparative study of surface structuring of biometals by UV nanosecond Nd:YVO4 laser

“…Nanosecond laser technology is widely adopted in the industry for micromachining (based on time and cost-effectiveness) [9,10]. With regards to most adequate laser wavelength for metal micromachining, it must be taken into account that the absorption coefficient of metals is generally higher in the UV range compared to that in the IR region, which should provide a lower ablation threshold for UV pulses [11].…”

Fundamental investigations of ps-laser burst-mode on common metals for an enhanced ablation process

“…Several singlepulse ablation studies for metals have already been reported for pulse durations from ns-to fs-pulses [11][12][13][14][15][16][17][18][19][20][21][22] . Furthermore a multitude of studies exhibited the influence of multi-laser pulses to different materials [3,5,17,18,[23][24][25] . However, those studies concentrated on reporting the influence of multi-laser pulses for a large number of pulses from 10 up to several of 100.…”