Observation of Laser-induced Explosion of Solid Materials and Correlation with Theory

Gagliano, F. P.; Paek, Un-Chul

doi:10.1364/ao.13.000274

Cited by 96 publications

(25 citation statements)

References 4 publications

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“…The temperature profiles inside the target were estimated by numerically solving the usual one-dimensional heat diffusion equation [23][24][25] for each laser fluence. The thermo-physical properties of ZnO are not known at high temperatures or in the liquid phase.…”

Section: Resultsmentioning

confidence: 99%

“…For fluences above 2.5 J/cm 2, the simulated temperature profile inside the target showed a different behaviour, with the maximum value displaced inside the depth of the sample. Such a superheating effect can lead to microexplosions within the melted material with subsequent adverse effects on eventual film quality [23][24][25]. Areas corresponding to bulk microexplosions predicted by the temperature simulation can clearly be seen in Fig.…”

Section: Resultsmentioning

confidence: 99%

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Effects of laser wavelength and fluence on the growth of ZnO thin films by pulsed laser deposition

Crăciun

Amirhaghi

Crǎciun

et al. 1995

Applied Surface Science

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Transparent, electrically conductive and c-axis oriented ZnO thin films have been grown by the pulsed laser deposition (PLD) technique on silicon and Coming glass substrates employing either a KrF excimer laser (3. = 248 nm) or a frequency-doubled Nd:YAG laser (3. = 532 rim). The crystalline structure, surface morphology, optical and electrical properties of the deposited films were found to depend not only on the substrate temperature and oxygen partial pressure, but also on the irradiation conditions. The quality of the ZnO layers grown by the shorter wavelength laser was always better than that of the layers grown by the longer wavelength, under otherwise identical deposition conditions. This behaviour was qualitatively accounted for by the results of the numerical solution of a one-dimensional heat diffusion equation which indicated a strong superheating effect of the melted target material for the case of frequency-doubled Nd:YAG laser irradiations. By optimizing the deposition conditions we have grown, employing the KrF laser, very smooth c-axis oriented ZnO films having a full-width at half-maximum value of the (002) X-ray diffraction value less than 0.16 ° and optical transmittance around 85% in the visible region of the spectrum at a substrate temperature of only 300°C.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Effects of laser wavelength and fluence on the growth of ZnO thin films by pulsed laser deposition

Crăciun

Amirhaghi

Crǎciun

et al. 1995

Applied Surface Science

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“…[27] In the be calculated from the Young-Laplace equation and modicase of intense laser energy, bubbles generally grow due to fied Van der Waals equations, respectively: the high energy influx. This homogeneous bubble growth, when combined with instability, will possibly lead to the P v ϭ P l ϩ 2 r e [20] so-called explosive boiling. Explosive-type boiling has been observed in a laser-matter interaction experiment.…”

Section: A Free Surface Evolution: Narrow-band Level Set Methodsmentioning

confidence: 99%

Modeling of laser keyhole welding: Part I. mathematical modeling, numerical methodology, role of recoil pressure, multiple reflections, and free surface evolution

Mazumder

Mohanty³

2002

Metall Mater Trans A

246

103

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A three-dimensional laser-keyhole welding model is developed, featuring the self-consistent evolution of the liquid/vapor (L/V) interface together with full simulation of fluid flow and heat transfer. Important interfacial phenomena, such as free surface evolution, evaporation, kinetic Knudsen layer, homogeneous boiling, and multiple reflections, are considered and applied to the model. The level set approach is adopted to incorporate the L/V interface boundary conditions in the Navier-Stokes equation and energy equation. Both thermocapillary force and recoil pressure, which are the major driving forces for the melt flow, are incorporated in the formulation. For melting and solidification processes at the solid/liquid (S/L) interface, the mixture continuum model has been employed. The article consists of two parts. This article (Part I) presents the model formulation and discusses the effects of evaporation, free surface evolution, and multiple reflections on a steady molten pool to demonstrate the relevance of these interfacial phenomena. The results of the full keyhole simulation and the experimental verification will be provided in the companion article (Part II).

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“…The tendency for ablation to slow down at the fibrous/sclerotic base of the plaque or residual media is consistent with its pink (nonyellow) color. This is a useful selective effect particularly when the normal tissue underlying a plaque is completely (18). In the early stages (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…To examine the selective ablative effect ofthis laser histologically, the laser output was focused with a 20-cm focal-length quartz convex lens to 2-mm diameter spots on 20 specimens from three cadavers. Atheromatous and adjacent normal regions were irradiated with multiple pulses at a rate of 1 Hz and a fluence of 18 Analysis of Ablation Products. Ablation debris was collected by placing a microscope slide in the path of the laser radiation, 2 cm from the specimen.…”

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confidence: 99%

Selective ablation of atheromas using a flashlamp-excited dye laser at 465 nm.

Prince¹,

Deutsch²,

Shapiro³

et al. 1986

Proc. Natl. Acad. Sci. U.S.A.

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Ablation of human atheromas with laser pulses that had only a small effect on normal artery tissue was shown in vitro in air and under saline using 1-psec pulses at 465 nm from a flashlamp-excited dye laser. At this wavelength, there is preferential absorption in atheromas due to carotenoids. The threshold fluence for ablation was 6.8 ± 2.0 J/cm2 for atheromas and 15.9 ± 2.2 J/cm2 for normal aorta tissue. At a fluence of 18 J/cm2 per pulse, the ablated mass per unit of energy ranged from 161 to 370 ,ug/J for atheromas and from 50 to 74 1Lg/J for normal aorta tissue. Ablation products consisted of cholesterol crystals, shredded collagen fibers, and small bits of calcific material. Most debris was less than 100Mum in diameter, but a few pieces were as large as 300 Mum.High-speed photography of ablation in air suggested explosive ejection of debris, caused by vapor formation, at speeds on the scale of 300 m/sec. Histological analysis showed minimal thermal damage to residual tissue. These data indicate that selective laser ablation of atheromas is possible in vitro.The ability to deliver laser energy to arteries via fine optical fibers offers the possibility of unclogging obstructed arteries without the trauma of surgery or general anaesthesia (1). This procedure, called laser endarterectomy or laser angioplasty, is now being evaluated in early clinical trials (2, 3). Its use thus far, however, has been limited, apparently due to perforations, aneurysms, and other forms of inadvertent laser damage, to adjacent and underlying normal tissues (2-6). Angioscopic (7) and radiographic visualization or other techniques (8) may help in aiming laser radiation at plaque. Laser endarterectomy would be much safer, however, ifthe radiation preferentially ablated atheroma and thrombus. In the ideal case, laser light would be delivered uniformly inside an obstructed artery, and only the obstructing material would be ablated.Preferential ablation of atheromas has previously been accomplished by first staining atheromas with a dye and then ablating with laser radiation that is absorbed by the dye (9, 10). A simpler method of achieving preferential ablation might be to take advantage ofexisting, endogenous, preferential absorption in the atheromas. The waveband from 450 to 500 nm has been identified as having a 2-fold preferential absorption in atheromas due to carotenoid pigments (11). In this study we have characterized preferential ablation of atheromas, in vitro, using a flashlamp-excited dye laser emitting radiation in this waveband at an appropriate pulse width and fluence. METHODS Radiation Source. Laser radiation at 465 nm was provided by a flashlamp-excited dye laser (Candela SLL 500 Coax) with 1.5 x 10-4 M coumarin 445 (Exciton C445) in methanol/distilled water (1:1, vol/vol). This laser generated 1-,usec pulses (full width at half-maximum) at a repetition rate of 1 Hz with energies up to 1.5 J per pulse. Laser wavelength, measured with a grating monochromator (Bausch and Lomb 33-86-76), ranged from 459 to 470 nm w...

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Observation of Laser-induced Explosion of Solid Materials and Correlation with Theory

Cited by 96 publications

References 4 publications

Effects of laser wavelength and fluence on the growth of ZnO thin films by pulsed laser deposition

Effects of laser wavelength and fluence on the growth of ZnO thin films by pulsed laser deposition

Modeling of laser keyhole welding: Part I. mathematical modeling, numerical methodology, role of recoil pressure, multiple reflections, and free surface evolution

Selective ablation of atheromas using a flashlamp-excited dye laser at 465 nm.

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