Study on the ablation threshold induced by pulsed lasers at different wavelengths

Torrisi, L.; Borrielli, A.; Margarone, D.

doi:10.1016/j.nimb.2006.12.144

Cited by 94 publications

(58 citation statements)

References 19 publications

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“…14,16 A comparison study of the ablation threshold of several materials including metals at three wavelengths, namely 1064, 532, and 248 nm, leads one to conclude that the prevalent mechanism for ablation differs from thermal when photon energy becomes higher than the binding energy of the target material. 17 In addition, photoionization of Cu neutrals was reported to occur at lower fluences for 193 nm than for 351 nm, supporting the existence of single photon ionization even at a photon energy smaller than the ionization potential. 12 In spite of the reduced number of reports comparing different laser wavelengths, it seems clear that the plasma features produced at 193 nm cannot directly be extrapolated from those produced at longer wavelengths.…”

Section: à2mentioning

confidence: 92%

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Dynamics of ions produced by laser ablation of several metals at 193 nm

Baraldi

Perea

Afonso

2011

Journal of Applied Physics

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Influence of excited state spatial distributions on plasma diagnostics: Atmospheric pressure laser-induced He-H2 plasma J. Appl. Phys. 112, 083302 (2012) Characterizing the energy distribution of laser-generated relativistic electrons in cone-wire targets Phys. Plasmas 19, 103108 (2012) Verification of the physical mechanism of THz generation by dual-color ultrashort laser pulses Appl. Phys. Lett. 101, 161104 (2012) ORION laser target diagnostics Rev. Sci. Instrum. 83, 10D732 (2012) Target normal sheath acceleration sheath fields for arbitrary electron energy distribution Phys. Plasmas 19, 083115 (2012) Additional information on J. Appl. Phys. This work reports the study of ion dynamics produced by ablation of Al, Cu, Ag, Au, and Bi targets using nanosecond laser pulses at 193 nm as a function of the laser fluence from threshold up to 15 J cm À2 . An electrical (Langmuir) probe has been used for determining the ion yield as well as kinetic energy distributions. The results clearly evidence that ablation of Al shows unique features when compared to other metals. The ion yield both at threshold (except for Al, which shows a two-threshold-like behavior) and for a fixed fluence above threshold scale approximately with melting temperature of the metal. Comparison of the magnitude of the yield reported in literature using other wavelengths allows us to conclude its dependence with wavelength is not significant. The evolution of the ion yield with fluence becomes slower for fluences above 4-5 J cm À2 with no indication of saturation suggesting that ionization processes in the plasma are still active up to 15 J cm À2 and production of multiple-charged ions are promoted. This dependence is mirrored in the proportion of ions with kinetic energies higher than 200 eV. This proportion is not significant around threshold fluence for all metals except for Al, which is already 20%. The unique features of Al are discussed in terms of the energy of laser photons (6.4 eV) that is enough to induce direct photoionization from the ground state only in the case of this metal.

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Section: à2mentioning

confidence: 92%

“…10 In addition, we have chosen to study Al because it has been the most widely studied metal using not only 193 nm (Ref. 10) but mainly other wavelengths in the visible and near infrared 13,14,16,17,20 and thus makes a very good case for comparing to results reported in literature.…”

Section: à2mentioning

confidence: 99%

Dynamics of ions produced by laser ablation of several metals at 193 nm

Baraldi

Perea

Afonso

2011

Journal of Applied Physics

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“…The difference of Fth between Al2O3 and AlN in this study can be assigned to the different absorption of the materials at 1064 nm. Since ablation thresholds depend on, e.g., the optical absorption that varies with wavelength [17,18] and on the number of pulses [19,20], Fth cannot be directly compared between different studies. In addition also the pulse length has an influence on the ablation threshold with by trend shorter pulses result in smaller thresholds [13].…”

Section: Ablation Thresholdmentioning

confidence: 99%

Micromachining of AlN and Al2O3 Using Fiber Laser

2014

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Abstract:We report on high precision high speed micromachining of Al2O3 and AlN using pulsed near infrared fiber laser. Ablation thresholds are determined to be 30 J/cm 2 for alumina and 18 J/cm 2 for aluminum nitride. The factors influencing the efficiency and quality of 3D micromachining, namely the surface roughness, the material removal rate and the ablation depth accuracy are determined as a function of laser repetition rate and pulse overlap. Using a fluence of 64 J/cm², we achieve a material removal rate of up to 94 mm³/h in Al2O3 and 135 mm³/h in AlN for high pulse overlaps (89% and 84%). A minimum roughness of 1.5 μm for alumina and 1.65 μm for aluminum nitride can be accomplished for medium pulse overlaps (42% to 56%). In addition, ablation depth deviation of the micromachining process of smaller than 8% for alumina and 2% for aluminum nitride are achieved. Based on these results, by structuring exemplarily 3D structures we demonstrate the potential of high quality and efficient 3D micromachining using pulsed fiber laser.

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“…When the laser fluence reaches 10 12 − 10 14 W/m 2 , laser ablation (LA) forms [39][40][41][42][43][44][45][46][47][48][49] . LA is the formation of a high-temperature high- Fig.…”

Section: Introductionmentioning

confidence: 99%

Non-contact and non-destructive Lamb wave generation using laser-induced plasma shock wave

Hosoya

Yoshinaga

Kanda

et al. 2018

International Journal of Mechanical Sciences

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a b s t r a c tThis paper proposes a non-contact and non-destructive method to generate Lamb waves against a target structure using the impulse excitation force generated by laser-induced plasma (LIP). When a high power pulse laser is irradiated in air and its laser fluence exceeds 10 15 W/m 2 , a plasma is formed. While the plasma in air expands in high speed, shock waves on the spherical surface are generated and these shock waves become the impulse excitation force against a target structure, resulting in the non-contact and non-destructive approach. A 2024 aluminum alloy plate is used as the test piece in the experiment, and the dynamic characteristics of the Lamb waves generated from LIP shock waves are measured. Phase velocity and group velocity of generated Lamb waves were compared to the calculated values from Rayleigh-Lamb frequency equations and we found that maximum error was 5% and its frequency component included at least 400 kHz. Further, we investigated the relationship between the distance from the LIP shock wave-generating location to a test piece and the dynamic characteristics of the generated Lamb waves. This method can control the amplitude and the frequency components of generated Lamb waves by changing this distance.

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Study on the ablation threshold induced by pulsed lasers at different wavelengths

Cited by 94 publications

References 19 publications

Dynamics of ions produced by laser ablation of several metals at 193 nm

Dynamics of ions produced by laser ablation of several metals at 193 nm

Micromachining of AlN and Al2O3 Using Fiber Laser

Non-contact and non-destructive Lamb wave generation using laser-induced plasma shock wave

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