Physical and material aspects in using visible laser pulses of nanosecond duration for ablation

Körner, Carolin; Mayerhofer, R.; Hartmann, Markus; Bergmann, H. W.

doi:10.1007/bf01567639

Cited by 116 publications

(35 citation statements)

References 3 publications

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“…1 moves towards higher fluences for metals with larger heat of fusion: Al (10.7 kJ/mol), Ni (17.5 kJ/mol), Mo (27.6 kJ/mol), and W (35.3 kJ/mol). The lattice is heated during the nanosecond pulse, so that instead of solid-gas ablation, vaporization occurs from the surface of the molten material even at lower intensities, and melt ejection is possible [17,18]. Due to the sharp increase with high-energy nanosecond pulses, the drilling rate can be comparable or superior relative to that of picosecond pulses, as observed for Ni, SS302, and Mo.…”

Section: Drilling Rate Of Five Metals With Pico-and Nanosecond Pulsesmentioning

confidence: 86%

“…In contrast to ablation with picosecond pulses, the drilling rate with nanosecond pulses grows sharply with increasing fluence soon after reaching the threshold. According to [17], this can be attributed to the sharp transition from evaporation near the threshold to melt ejection when the absorbed power density is close to approximately 1 GW/cm 2 (6 J/cm 2 for 6 ns). The region of sharp increase in the curves for 6 ns in Fig.…”

Section: Drilling Rate Of Five Metals With Pico-and Nanosecond Pulsesmentioning

confidence: 98%

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

2012

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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.

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Section: Drilling Rate Of Five Metals With Pico-and Nanosecond Pulsesmentioning

confidence: 86%

Section: Drilling Rate Of Five Metals With Pico-and Nanosecond Pulsesmentioning

confidence: 98%

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

2012

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“…By comparing the groove bottom in HPHT diamond in Figures 3a and 4a, it can be assumed that higher energy at the lower surface caused much spalling due to diamond's brittle nature, resulting in a rough bottom [25,26]. Material removal appears to be dominated by spalling rather than diamond conversion into graphite and its subsequent sublimation [27].…”

Section: Appl Sci 2017 7 815 8 Of 14mentioning

confidence: 99%

Laser Irradiation Responses of a Single-Crystal Diamond Produced by Different Crystal Growth Methods

Takayama

Yan

2017

Applied Sciences

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Abstract:Responses of two types of single-crystal diamonds, prepared by chemical vapour deposition (CVD) and high pressure high temperature synthesis (HPHT) methods, respectively, to a nanosecond pulsed neodymium-doped yttrium aluminium garnet (Nd:YAG) laser were investigated and compared. It was found that due to the difference in the transmission rate and refractive index, the laser-induced surface/subsurface features of the two types of samples were distinctly different. For the CVD sample, destructive interference takes place on the upper surface, leading to direct ablation of smooth grooves with deposition of graphite. For the HPHT sample, however, laser-induced grooves were formed on the reverse side of the irradiation surface (namely, the lower surface) at certain laser fluences due to the constructive interference phenomenon of the laser and the high refractive index of the material. The reverse-side irradiation resulted in the formation of deep and sharp grooves with rough bottoms and insignificant deposition of graphite on the area surrounding the groove. The machining thresholds for the upper and lower surfaces of both types of diamonds were experimentally obtained and theoretically verified. The findings of this study provide important process criteria for laser machining of different kinds of diamonds. The reverse-side irradiation method enables efficient machining of deep grooves in diamonds using a lower power laser.

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“…Different from removing just the surface layers, in the machining of the bulk anodic alumina film, the irradiated laser energy must be sufficiently high to melt and vaporize the laser irradiated area. A number of models have been proposed and demonstrated for the ablation of materials by laser irradiation in the past few decades [17][18][19][20]. In general, it has been reported that nanosecond laser ablation of dielectrics is due to multi-photon absorption followed by an avalanche process.…”

Section: Modes Of Laser-machining Of Anodic Alumina Filmmentioning

confidence: 99%

Laser micromachining of porous anodic alumina film

et al. 2007

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A laser direct-write process on porous anodic alumina film is carried out for the fabrication of microstructure on the film, using nanosecond, second harmonic Nd:YAG laser. Laser micromachining can be preformed in two different ways on colored and pore-sealed anodic alumina film, to generate microstructures on the film. Removal of the aluminum substrate before laser irradiation greatly improves the shape characteristics of the microstructure. The depth of microstructures can be controlled by the power and the scanning speed of the laser beam. Several structures with depths from 1 to 35μm were fabricated on anodic alumina film with good precision and reproducibility.

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Physical and material aspects in using visible laser pulses of nanosecond duration for ablation

Cited by 116 publications

References 3 publications

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

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

Laser Irradiation Responses of a Single-Crystal Diamond Produced by Different Crystal Growth Methods

Laser micromachining of porous anodic alumina film

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