Optodynamic energy conversion efficiency during laser ablation on metal surfaces measured by shadow photography

Gregorčič, Peter; Zadravec, Jure; Možina, Janez; Jezeršek, Matija

doi:10.1007/s00339-014-8412-5

Cited by 9 publications

(10 citation statements)

References 18 publications

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“…For monitoring the optodynamic phenomena, we simultaneously employed two measuring methods: shadowgraphy [7] and LIBS [12]. Shock-wave dynamics was measured by shadowgraphy.…”

Section: Methodsmentioning

confidence: 99%

“…The OD energy-conversion efficiency 0 / p E E   , defined as the ratio between the shock wave energy E0 and the pulse energy Ep [7], can be obtained by fitting the Jones model to the measured results [21]. Therefore, the solid curves in Fig.…”

Section: Visualization Of Shock-wave Dynamicsmentioning

confidence: 99%

“…Here, the acoustic waves have been measured by a microphone and a laser-beam-deflection probe [2,[4][5][6]. The main idea behind these methods is to detect the time-of-flight of the shock wave, which is generated during the laser ablation, since the shock wave's velocity varies with the optodynamic (OD) energy-conversion efficiency, defined as the ratio between the mechanical energy of the macroscopic motion and the excitation-pulse energy [7]. This variation results in different time-of-flights at a constant distance between the probe or microphone and the laser-material interaction site.…”

Section: Introductionmentioning

confidence: 99%

“…The main aim of this paper is to simultaneously use two monitoring methods, shadowgraphy [7] and LIBS [12] and to evaluate both techniques for the analysis and monitoring of laser ablation of copper from the printed circuit boards. LIBS has been chosen, since in the last decade it has been extensively used for selective thin-layer removal [13][14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of laser-induced thin-layer removal by using shadowgraphy and laser-induced breakdown spectroscopy

et al. 2016

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Shadow photography and laser-induced breakdown spectroscopy (LIBS) are studied as methods for monitoring the selective removal of thin (i.e., under 100 m) layers by laser ablation. We used a laser pulse of 5 ns and 16 mJ at 1064 nm to ablate an 18-m-thin copper layer from the fiberglass substrate. On the basis of shadowgraphs of the laser-induced shock waves, we measured the optodynamic energy-conversion efficiency, defined as the ratio between the mechanical energy of the shock wave and the excitation-pulse energy. Our results show that this efficiency is significantly higher for the laser-pulse-copper interaction than for the interaction between the excitation pulse and the substrate. LIBS was simultaneously employed in our experimental setup. The optical emission from the plasma plume was collected by using a spectrograph and recorded with a streak camera. We show that advancing of laser ablation through the copper layer and reaching of the substrate can be estimated by tracking the spectral region between 370 nm and 500 nm. Therefore, the presented results confirm that LIBS method enables an on-line monitoring needed for selective removal of thin layers by laser.

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“…For monitoring the optodynamic phenomena, we simultaneously employed two measuring methods: shadowgraphy [7] and LIBS [12]. Shock-wave dynamics was measured by shadowgraphy.…”

Section: Methodsmentioning

confidence: 99%

Section: Visualization Of Shock-wave Dynamicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Evaluation of laser-induced thin-layer removal by using shadowgraphy and laser-induced breakdown spectroscopy

et al. 2016

Self Cite

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“…This paper was based on the research into the parallel illumination of a high-power infrared narrow-pulse laser, the signal trigger, the sequential control, and the reception of the image sensor. We proposed a method based on high-speed shadow imaging to obtain the image of the projectile's position when the LSVM system generates the timing signal [18][19][20][21][22], which uses the image processing to obtain the target deviation of the projectile relative to the light screen, thereby correcting the target distance of the LSVM system. It is intended to measure and calibrate the consistency of the optoelectronic response of the LSVM system by the proposed method, and improve the measuring accuracy of the projectile's velocity.…”

Section: Introductionmentioning

confidence: 99%

Research on Target Deviation Measurement of Projectile Based on Shadow Imaging Method in Laser Screen Velocity Measuring System

Chu

Zhao

Liu

et al. 2020

Sensors

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In the laser screen velocity measuring (LSVM) system, there is a deviation in the consistency of the optoelectronic response between the start light screen and the stop light screen. When the projectile passes through the light screen, the projectile’s over-target position, at which the timing pulse of the LSVM system is triggered, deviates from the actual position of the light screen (i.e., the target deviation). Therefore, it brings errors to the measurement of the projectile’s velocity, which has become a bottleneck, affecting the construction of a higher precision optoelectronic velocity measuring system. To solve this problem, this paper proposes a method based on high-speed shadow imaging to measure the projectile’s target deviation, ΔS, when the LSVM system triggers the timing pulse. The infrared pulse laser is collimated by the combination of the aspherical lens to form a parallel laser source that is used as the light source of the system. When the projectile passes through the light screen, the projectile’s over-target signal is processed by the specially designed trigger circuit. It uses the rising and falling edges of this signal to trigger the camera and pulsed laser source, respectively, to ensure that the projectile’s over-target image is adequately exposed. By capturing the images of the light screen of the LSVM system and the over-target projectile separately, this method of image edge detection was used to calculate the target deviation, and this value was used to correct the target distance of the LSVM to improve the accuracy of the measurement of the projectile’s velocity.

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Propulsion effects after laser ablation in water, confined by different geometries

2020

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A Nd:YAG laser with 7-ns pulses and pulse energies up to 10 mJ is used to induce an optical breakdown in the front surface of an aluminum rod, covered by a water layer. The rod is part of a ballistic pendulum. In this way we study the propulsion effects by means of coupling coefficient and energy-conversion efficiency with respect to different confining geometries, volumes of water applied to the front surface of the rod, and the distance of this surface from the laser-beam focus.Holes with different dimensions are drilled on the target surface and filled with different volumes of water to examine the influence of the confinement by the liquid (a free boundary) and a solidsurface geometry on laser ablation effects. The rod movement and the water ejection after laser ablation are acquired by a high-speed camera with 10k frames per second. The results show that the confinement by cavity substantially increases the propulsion effects by shaping the ejected flow of the liquid, while the cavitation bubble, induced inside the water layer plays a significant role in propulsion efficiency. From the presented results, it follows that the laser-propelled rod carries below 0.5% of the total mechanical energy after propulsion, while the rest of this energy represents the kinetic energy of the ablated water. As expected, moving the target surface away from the focal position decreases the ablative-propulsion efficiency. When the focus is moved inside the solid target the decrease occurs due to lower conversion of the pulse energy into the energy of the cavitation bubble. If the focus is moved from the surface outward, the bubble moves towards the liquid-gas interface and it is not able to efficiently eject all the liquid from the target.

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Optodynamic energy conversion efficiency during laser ablation on metal surfaces measured by shadow photography

Cited by 9 publications

References 18 publications

Evaluation of laser-induced thin-layer removal by using shadowgraphy and laser-induced breakdown spectroscopy

Evaluation of laser-induced thin-layer removal by using shadowgraphy and laser-induced breakdown spectroscopy

Research on Target Deviation Measurement of Projectile Based on Shadow Imaging Method in Laser Screen Velocity Measuring System

Propulsion effects after laser ablation in water, confined by different geometries

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