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1.
Deep drilling on a silicon plate with a femtosecond laser: experiment and model analysis 总被引:1,自引:0,他引:1
T. Matsumura T. Nakatani T. Yagi 《Applied Physics A: Materials Science & Processing》2007,86(1):107-114
The ablation rate when drilling fine holes having large aspect ratios in silicon substrates with femtosecond laser pulses was estimated from mechanically ground cross sections of the ablated holes. The ablation rate shows a dramatic change at the depth at which the laser pulse reaches a certain fluence, which is nearly constant when the initial laser fluence was varied from 14.5 to 59.4 J/cm2. The ablation rate, threshold fluence, in three fluence domains, and the transition fluences at which the ablation rate shows a dramatic change, were derived. However, when a pulse energy of 200 μJ was used a much greater ablation rate was obtained, suggesting that another fluence domain for larger ablation rates exists. The experimentally obtained hole depths as a function of shot numbers were reproduced by a theoretical model, which incorporates laser pulse attenuation in the holes that is the same as that in waveguides for some attenuation coefficient and ablation rates for three fluence domains. PACS 42.62.-b; 42.65.Re; 78.40.Fy; 78.47.+p; 81.20.Wk 相似文献
2.
Minju Ying Yueyuan Xia Yuming Sun Yuchen Ma Mingwen Zhao Xiaotao Hao Xiangdong Liu 《Optics & Laser Technology》2003,35(6):475-480
Optical emission spectra of Nd:YAG laser ablation of KTiOPO4 (KTP) crystal and SnO2:Sb transparent conducting thin film were recorded and analyzed in vacuum and in air. The integral intensities of spectral lines from laser-ablated KTP crystal were obtained as functions of distance from the target surface and laser power density in vacuum and in air. The ambient gas effects on pulsed laser ablation of target were discussed. We also performed laser ablation of SnO2:Sb transparent conducting thin film in air and the electron temperature and full-width at half-maximum (FWHM) of atomic and ionic spectral lines in the plasma were quantified using Boltzmann plot method and Lorentzian fit, respectively. Integral intensities of atomic and ionic Sn spectral lines were also obtained as functions of distance from the target surface and laser irradiance. The intensity ratio of ionic and atomic Sn spectral lines as a function of laser power density was got which gives some information about the variation of ionization ratio with laser irradiance in the plasma produced by high-power laser. 相似文献
3.
Xuefei Li Lingnan Kong Jinghai Yang Ming Gao Tingjing Hu Xingtong Wu Ming Li 《Applied Physics A: Materials Science & Processing》2013,110(3):735-739
Femtosecond laser material processing as micromachining and nanoparticles fabrication require a careful control of the fluences deposited on the samples. In many cases, best results are obtained by using fluences slightly above the Laser Ablation Threshold (LAT), therefore its accurate determination is an important requirement. LAT can be obtained by measuring the intensity of the acoustic signal generated during the ablation process as a function of the laser fluence. In this work femtosecond laser ablation thresholds of commercially polished stainless steel plates, white high impact polystyrene, frosted glass, antique rag papers and silicon oxynitride thin films were determined by using laser ablation induced photoacoustics (LAIP). Results were compared with similar data previously obtained by using a nanosecond Nd:YAG laser. 相似文献
4.
Experimental investigation of ablation efficiency and plasma expansion during femtosecond and nanosecond laser ablation of silicon 总被引:1,自引:0,他引:1
X. Zeng X.L. Mao R. Greif R.E. Russo 《Applied Physics A: Materials Science & Processing》2005,80(2):237-241
Femtosecond laser (Ti:sapphire, 100 fs pulse duration) ablation of silicon in air was compared with nanosecond laser (Nd:YAG, 3 ns pulse duration) ablation at ultraviolet wavelength (266 nm). Laser ablation efficiency was studied by measuring crater depth as a function of pulse number. For the same number of laser pulses, the fs-ablated crater was about two times deeper than the ns-crater. The temperature and electron number density of the laser-induced plasma were determined from spectroscopic measurements. The electron number density and temperature of fs-induced plasmas decreased faster than ns-induced plasmas due to different energy deposition mechanisms. Images of the laser-induced plasma were obtained with femtosecond time-resolved laser shadowgraph imaging. Plasma expansion in both the perpendicular and the lateral directions were compared. PACS 52.38.Mf; 52.30.-q 相似文献
5.
A free-running Er:YAG laser is used to ablate polyethylene glycol and the ablation yield is studied as a function of molecular weight (1000-10,000 g/mol) and laser fluence (8-25 J/cm2). A steady-state ablation mechanism is proposed which includes recoil-induced expulsion as the primary contributor to the ablation yield. It is also proposed that the formation of a molten layer is a necessary part of the ablation mechanism because the calculated tensile strengths for the solid polymer are too large to permit fracture of the target due to the laser-induced stress transient. The ablation yield is found to depend in a sigmoidal fashion upon laser fluence, thus implying a variable ablation enthalpy. Finally, the current results are compared with that obtained previously with a free electron laser. 相似文献
6.
7.
A.H. El-Astal I. Weaver G.W. Martin A. Al-Khateeb T.P. Williamson M.J. Lamb C.L.S. Lewis T. Morrow 《Applied Physics A: Materials Science & Processing》1999,69(7):S573-S576
A Langmuir probe was used as a diagnostic of the temporally evolving electron number densities within a low-temperature laser-ablated titanium plasma expanding in vacuum. Measurements were made following ablation by a KrF excimer laser (248 nm, F=30 ns) and a frequency-doubled Nd:YAG laser (532 nm, F=7.5 ns) for laser power densities between 85 MW cm-2 and 1130 MW cm-2 on target. Electron number density data were obtained from the saturation electron current region of the probe (I/V) characteristic. Peak electron number densities in the range 1.5᎒10 cm-3 to 1.5᎒13 cm-3 were measured, at a distance of 5 cm along the target normal, for the laser power range investigated. Above ablation threshold the temporally integrated electron flux increased linearly with incident power density for both ablation wavelengths. The ablation thresholds, in terms of peak power density within the laser spot on the target, were found to be 85ᆨ MW cm-2 for KrF ablation and 300ᇆ MW cm-2for 2P YAG ablation. 相似文献
8.
Cinthya Toro Nicolás D. Gómez Norberto G. Boggio Jorge Codnia M. Laura Azcárate Carlos Rinaldi 《Applied Physics A: Materials Science & Processing》2014,117(1):43-47
In this article, we present an experimental study of the effect of conical section nozzles coupled to solid targets on laser ablation propulsion. The impulse produced on the target by laser ablation was measured in terms of the coupling coefficient C m using a piezoelectric (PZT) sensor. The standard deviation of the PZT signal was used as an estimator of the transferred impulse. The ablation was performed with a TEA CO2 laser at room temperature and atmospheric pressure. The targets were pellets of 90/10 % w/w Zn/CaCO3 concentration ratio. Aluminum nozzles with conical section were coupled to these propellant pellets. A comparative study of the variation of C m using nozzles of different inlet and outlet diameters of the ejected material as well as of different heights was made. The results demonstrate that for the pellet composition analyzed, as the nozzle’s height increases and its diameter decreases improvements up to 250 % respect to the target without nozzle are obtained. These are promising results for the potential development of laser ablation microthrusters. 相似文献
9.
Femtosecond laser pulse ablation of GaAs and InP: studies utilizing scanning and transmission electron microscopy 总被引:2,自引:0,他引:2
A. Borowiec M. MacKenzie G.C. Weatherly H.K. Haugen 《Applied Physics A: Materials Science & Processing》2003,77(3-4):411-417
Single pulse laser ablation of GaAs and InP using 130 fs light pulses at 800 nm was studied with various techniques, in particular, scanning and transmission electron microscopies. The final state of the material near the laser-ablated region following femtosecond ablation was characterized in detail for selected laser fluences. Threshold ablation laser fluences were also obtained for both compounds. PACS 61.80.Ba; 64.60.-i; 79.20.Ds 相似文献
10.
S. P. Banerjee R. Fedosejevs 《Applied Physics A: Materials Science & Processing》2014,117(3):1473-1478
Single-shot ablation threshold for thin chromium film was studied using 266 nm, femtosecond laser pulses. Chromium is a useful material in the nanotechnology industry and information on ablation threshold using UV femtosecond pulses would help in precise micromachining of the material. The ablation threshold was determined by measuring the ablation crater diameters as a function of incident laser pulse energy. Absorption of 266 nm light on the chromium film was also measured under our experimental conditions, and the absorbed energy single-shot ablation threshold fluence was \(46 \pm 5\) mJ/cm2. The experimental ablation threshold fluence value was compared to time-dependent heat flow calculations based on the two temperature model for ultrafast laser pulses. The model predicts a value of 31.6 mJ/cm2 which is qualitatively consistent with the experimentally obtained value, given the simplicity of the model. 相似文献
11.
12.
Li Li Zhang Duan-ming Li Zhi-hua Tan Xin-yu Fang Ran-ran 《Frontiers of Physics in China》2007,2(3):322-326
In this paper, the effect of the absorptivity of metal on femtosecond pulsed laser ablation is investigated. The formulas
for the absorptivity depending on target temperature are derived from Maxwell Equations and the Lambert-Beer’s law. Based
on this, a new two-temperature model is proposed to describe the femtosecond pulsed laser ablation with metal. Then, using
Au as an example, a finite difference method is employed to simulate the space-dependent and time-dependent absorptivity and
the target temperature. The temperature evolution of our model is compared with the result obtained form the heat conduction
model taking the absorptivity as constant. It is shown that the absorptivity plays an important role in the femtosecond pulsed
laser ablation. The results of this paper are helpful in choosing the best technical parameters in femtosecond pulsed laser
ablation.
相似文献
13.
The dynamics of tissue ablation using an Er:YAG laser were studied using flash photography and optical pump-probe techniques. Both normal-spiking-mode and Q-switched Er:YAG laser radiation were used to study the ablation of skin and bone. Time-resolved photographs of the ablation plume were obtained using a microscope-mounted camera together with pulsed illumination from an excimer-pumped dye laser. The velocity of the plume front, obtained from the photographs, was approximately 1400 m/s. The same velocity was also measured using an optical pump-probe technique. Both techniques indicate that material removal occurred after the end of the 90-ns-long Q-switched laser pulse and that each micropulse in the normal-spiking-mode pulse train was capable of ablating and rapidly ejecting tissue.This work was supported in part by the SDIO-MFEL Program under contract # N00014-86-K-0117 and by the Arthur O. and Gullan M. Wellman Foundation 相似文献
14.
K. Obata K. Sugioka T. Akane N. Aoki K. Toyoda K. Midorikawa 《Applied Physics A: Materials Science & Processing》2001,73(6):755-759
A collinear irradiation system of F2 and KrF excimer lasers for high-quality and high-efficiency ablation of hard materials by the F2 and KrF excimer lasers’ multi-wavelength excitation process has been developed. This system achieves well-defined micropatterning
of fused silica with little thermal influence and little debris deposition. In addition, the dependence of ablation rate on
various conditions such as laser fluence, irradiation timing of each laser beam, and pulse number is examined to investigate
the role of the F2 laser in this process. The multi-wavelength excitation effect is strongly affected by the irradiation timing, and an extremely
high ablation rate of over 30 nm/pulse is obtained between -10 ns and 10 ns of the delay time of F2 laser irradiation. The KrF excimer laser ablation threshold decreases and its effective absorption coefficient increases
with increasing F2 laser fluence. Moreover, the ablation rate shows a linear increase with the logarithm of KrF excimer laser fluence when the
F2 laser is simultaneously irradiated, while single KrF excimer laser ablation shows a nonlinear increase. The ablation mechanism
is discussed based on these results.
Received: 16 July 2001 / Accepted: 27 July 2001 / Published online: 2 October 2001 相似文献
15.
ArF laser surface modification of polyethersulfone film: Effect of laser fluence in improving surface biocompatibility 总被引:1,自引:0,他引:1
H. Pazokian S. Jelvani M. MollabashiJ. Barzin G. Azizabadi Farahani 《Applied Surface Science》2011,257(14):6186-6190
ArF laser treatment of polyethersulfone (PES) films was performed to improve biocompatibility of surfaces. For this purpose, the threshold fluence for laser ablation of PES was obtained from experimental measurements and then samples were irradiated at 2 separate ranges of fluences, i.e. below and above the ablation threshold. In order to investigate the physico-chemical changes, the modified surfaces were characterized by attenuated total reflectance (ATR) infrared spectroscopy and contact-angle measurements. The biocompatibility of the treated samples in comparison to those untreated was examined in vitro using a platelet adhesion test. The number of adhered platelets was obtained using the lactate dehydrogenase (LDH) method. For surfaces irradiated below the ablation threshold, a high reduction in the number of the adhered platelets was observed; while this number increased in samples treated at the fluence above the ablation threshold. The change in platelet adhesion was attributed to the change in chemistry and roughness of the irradiated surfaces. 相似文献
16.
The efficiency (mm3/(J pulse)) of laser ablation of paint was investigated with nanosecond pulsed Nd:YAG lasers (λ = 532 nm) as a function of the following laser beam parameters: pulse repetition rate (1-10,000 Hz), laser fluence (0.1-5 J/cm2) and pulse duration (5 ns and 100 ns). In our study, the best ablation efficiency (η ≅ 0.3 mm3/J) was obtained with the highest repetition rate (10 kHz) at the fluence F = 1.5 J/cm2. This ablation efficiency can be associated with heat accumulation at high repetition rate, which leads to the ablation threshold decrease. Despite the low thermal diffusivity and the low optical absorption of the paint (thermal confinement regime), the ablation threshold fluence was found to depend on the pulse duration. At high laser fluence, the ablation efficiency was lower for 5 ns pulse duration than for the one of 100 ns. This difference in efficiency is probably due to a high absorption of the laser beam by the ejected matter or the plasma at high laser intensity. Accumulation of particles at high repetition rate laser ablation and surface shielding was studied by high speed imaging. 相似文献
17.
Mezzapesa FP Ancona A Sibillano T De Lucia F Dabbicco M Lugarà PM Scamarcio G 《Optics letters》2011,36(6):822-824
We demonstrate that diode laser self-mixing interferometry can be exploited to instantaneously measure the ablation front displacement and the laser ablation rate during ultrafast microdrilling of metals. The proof of concept was obtained using a 50-μm-thick stainless steel plate as the target, a 120?ps/110?kHz microchip fiber laser as the machining source, and an 823?nm diode laser with an integrated photodiode as the probe. The time dependence of the hole penetration depth was measured with a 0.41?μm resolution. 相似文献
18.
Jeong Ho Ryu Gyeong Seon Park Kang Min Kim Chang Sung Lim Jong-Won Yoon Kwang Bo Shim 《Applied Physics A: Materials Science & Processing》2007,88(4):731-736
Pulsed laser ablation (PLA) in the liquid phase was successfully employed to synthesize calcium tungstate (CaWO4) nanocolloidal suspension. The crystalline phase, particle morphology and laser ablation mechanism for the colloidal nanoparticles
were investigated using XRD, TEM and SEM. The obtained colloidal suspension consisted of well-dispersed CaWO4 nanoparticles which showed a spherical shape with sizes ranging from 5 to 30 nm. The laser ablation and the nanoparticle
forming process were discussed under consideration of the photo-ablation mechanism, where the nanoparticles were generated
by rapid condensation of the plume in high pressured ethanol vapor. The optical properties of the prepared CaWO4 colloidal nanoparticles were analyzed in detail using XPS, Raman spectroscopy, UV-Vis spectroscopy and PL spectrophotometry.
The optical band gap was estimated by Tauc and Menths law.
PACS 42.62.-b; 82.70.Dd; 78.55.Hx; 81.07.Wx 相似文献
19.
为确定飞秒激光光束对微尺度结构的烧蚀深度,研究了给定功率条件下对应的激光束有效烧蚀焦距。提出采用激光焦点处获得的烧痕阵列图像及在离焦状态下提取烧痕图像特征,通过分析图像特征与离焦距离,获得激光束有效烧蚀焦距范围的方法。在激光束焦点附近的硅晶片表面烧蚀出斑痕阵列,向下逐渐减小焦距,采集硅晶片斑痕图像,提取斑痕平均像素面积及斑痕目标与背景之间的R分量灰度差,获得斑痕像素面积及灰度差随激光束焦距变化的曲线;向上逐渐增大焦距,提取并获得斑痕像素面积及灰度差随激光束焦距变化的曲线。结合激光束向下离焦阈值(633 μm)及向上离焦阈值(993 μm),确定20 mW输出功率条件下,飞秒激光在硅晶片材料表面的有效烧蚀深度为360 μm。采用中位值方法确定了激光束在硅晶片表面聚焦时的焦距为0.823 mm。实验表明,激光烧蚀斑痕像素面积及灰度差与激光束焦距之间的关系能够客观地反映激光束有效烧蚀焦距的变化范围。 相似文献
20.
Z.-M. Ren P.-N. Wang Y.-C. Du Z.-F. Ying F.-M. Li 《Applied Physics A: Materials Science & Processing》1997,65(4-5):407-409
2 radicals when the 355 and 1064 nm outputs of a Nd:YAG laser were applied. While for the 532 nm ablation, a relatively higher
concentration of excited atomic carbon was obtained. Different Raman and FTIR spectral features were observed from the deposited
films with different ablation wavelengths. The 532 nm laser ablation is proposed for the synthesis of high quality carbon
nitride films.
Received: 16 October 1996 / Accepted: 11 April 1997 相似文献