Time-resolved techniques as probes for the laser ablation process

Hauer, M.; Funk, David J.; Lippert, Thomas; Wokaun, Alexander

doi:10.1016/j.optlaseng.2004.03.013

Cited by 35 publications

(9 citation statements)

References 31 publications

(35 reference statements)

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“…The fluorescence of a Rhodamin 6G methanol solution upon excitation by the second harmonic of a Q-switched Nd:YAG ͑yttrium aluminum garnet͒ probe laser ͑ p : 5 ns͒ served as stroboscopic illumination to acquire shadowgraphs depicting instantaneous differences in the refractive index above the target surface by a synchronized charge-coupled device ͑CCD͒ camera equipped with a macro-objective. 29 The variable delay time between the two lasers was controlled by a delay generator ͑SRS DG 535, Stanford Research Systems͒. A modification to the setup, described in detail elsewhere, 30 was employed to visualize specifically the generated aerosol particles by laser-induced scattering.…”

Section: Methodsmentioning

confidence: 99%

Laser ablation characteristics of yttria-doped zirconia in the nanosecond and femtosecond regimes

Heiroth

Koch

Lippert

et al. 2010

Journal of Applied Physics

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The laser ablation characteristics of yttria-stabilized zirconia ͑YSZ͒ have been investigated as a function of the target microstructure and dopant level for different nanosecond-͓ArF, KrF, and XeCl excimers; Nd:YAG ͑yttrium aluminum garnet͒ ͑fourth harmonic͔͒ and femtosecond-laser sources ͓Ti:sapphire ͑fundamental and third harmonic͔͒. Particle ejection, which compromises the quality of coatings prepared by pulsed laser deposition ͑PLD͒, was analyzed in detail. Nanosecond-laser pulses cause a severe thermomechanical surface cracking and exfoliation of micron-sized fragments on a microsecond to millisecond time scale in the case of 8 -9.5 mol % Y 2 O 3 -doped, fully stabilized zirconia ͑8YSZ and 9.5YSZ͒ targets. As a consequence of the intrinsic material brittleness, fully stabilized YSZ coatings deposited by PLD contained particles for all tested conditions. Lower doped partially stabilized zirconia ͑3YSZ͒ exhibits a superior fracture toughness attributed to a laser-induced partial transition to the monoclinic phase, detected by Raman spectroscopy, which enables the deposition of particle-free dense thin films by conventional PLD using nanosecond-UV laser radiation at moderate fluences of 1.2-1.5 J / cm 2 . The ablation dynamics of ultrashort laser pulses differ fundamentally from the nanosecond regime as evidenced, e.g., by time-resolved shadowgraphy and light scattering experiments. Femtosecond pulses prevent the exfoliation of micron-sized fragments but result invariably in a pronounced ejection of submicron particles. The resulting PLD coatings are porous and reveal a large surface roughness as they consist of an agglomeration of nanoparticles. Femtosecond-NIR pulses provide a factor of 2.5-10 higher material removal rates compared to nanosecond-and femtosecond-UV pulses. The ablation metrics, i.e., threshold fluence and effective absorptivity, mainly depend on the laser wavelength while the pulse duration, target microstructure, and dopant level are of minor importance. Evidence is presented that incubation effects play a significant role in nanosecond-and femtosecond-laser ablations of YSZ enabling material removal at comparatively low fluences for sub-bandgap photon energies.

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Section: Methodsmentioning

confidence: 99%

Laser ablation characteristics of yttria-doped zirconia in the nanosecond and femtosecond regimes

Heiroth

Koch

Lippert

et al. 2010

Journal of Applied Physics

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“…Such detrimental effects can be mitigated through operation with small donor/receiver gaps or in a reduced pressure atmosphere . The influence of the process parameters in the TP ablation behavior and the dynamics of the laser‐generated flyer have been investigated in detail …”

Section: Lift From Solid Donor Filmsmentioning

confidence: 99%

Laser‐Induced Forward Transfer: Fundamentals and Applications

Serra

Piqué

2018

Adv Materials Technologies

253

191

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Laser‐induced forward transfer (LIFT) is a digital printing technique that uses a pulsed laser beam as the driving force to project material from a donor thin film toward the receiving substrate whereon that material will be finally deposited as a voxel. This working principle allows LIFT to operate with both solid and liquid donor films, which provides the technique with an unprecedented broad spectrum of printable materials, and thus makes it very competitive over other digital technologies, like inkjet printing. It is not only that LIFT can access a much wider range of ink viscosities and loading particle sizes; the possibility of printing from solid films allows the single‐step printing of multilayers and entire devices, and even makes possible 3D printing. This versatility translates, in turn, into a broad field of applications, from graphics production to printed electronics, from the fabrication of chemical sensors to tissue engineering. This monograph provides an extensive review of the LIFT technique, from its origins to the most recent achievements, focusing on the fundamental aspects of both its working principle and transfer dynamics, as well as on its broad range of applications.

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“…To address the issue of a possible photothermal contribution to the ablation mechanism, a nanosecond (ns) imaging technique56–59 was employed that produces a series of shadowgraphs of the air‐polymer interface. Two different experimental techniques were employed, which have been described in detail elsewhere 60. Briefly, direct imaging of the shockwave and ablation products has been utilized which yields very clear images (Figure 20 right), and an interferometric setup which allows a better analysis of the shockwave although the images look less clear (Figure 20 left).…”

Section: Discussionmentioning

confidence: 99%

Interaction of Photons with Polymers: From Surface Modification to Ablation

Lippert

2005

Plasma Processes & Polymers

137

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Summary: This work reviews the interaction of photons with polymers with an emphasis on UV laser ablation and surface modification using VUV lamps. Laser ablation of polymers is an established process in industrial applications, but the mechanisms of ablation are still controversial. Different polymers, such as poly(methyl methacrylate), polyimides and specially designed polymers are used as examples to show that the mechanism is a mixture of photochemical and photothermal features which are closely related to the polymer structure and properties. Different approaches to probe the ablation mechanisms and to improve ablation are discussed. Photoactive groups have been introduced into the polymer structure to improve the quality of ablation and to elucidate the ablation mechanisms. The experimental techniques to probe the ablation mechanism range from time‐resolved measurements, such as shadowgraphy, ToF‐MS, and ns‐surface interferometry to variations of the irradiation wavelengths and pulse lengths. The necessity for a critical evaluation of the experimental procedures and analysis is discussed exemplary for polyimides. The data for different types of polyimides are mixed up and some experimental procedures are possibly causing problems for the data evaluation. Various recent trends for laser ablation, such as ultrafast ablation or VUV ablation are also discussed. Surface modifications of polymers using VUV photons from lamps are discussed for oxidation and nitriding of poly dimethylsiloxane (PDMS) and polyolefines. The mechanism of the PDMS surface oxidation is presented in detail.

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Time-resolved techniques as probes for the laser ablation process

Cited by 35 publications

References 31 publications

Laser ablation characteristics of yttria-doped zirconia in the nanosecond and femtosecond regimes

Laser ablation characteristics of yttria-doped zirconia in the nanosecond and femtosecond regimes

Laser‐Induced Forward Transfer: Fundamentals and Applications

Interaction of Photons with Polymers: From Surface Modification to Ablation

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