WorldWideScience

Sample records for ablative laser propulsion

  1. A Review of Laser Ablation Propulsion

    International Nuclear Information System (INIS)

    Phipps, Claude; Bohn, Willy; Lippert, Thomas; Sasoh, Akihiro; Schall, Wolfgang; Sinko, John

    2010-01-01

    Laser Ablation Propulsion is a broad field with a wide range of applications. We review the 30-year history of laser ablation propulsion from the transition from earlier pure photon propulsion concepts of Oberth and Saenger through Kantrowitz's original laser ablation propulsion idea to the development of air-breathing 'Lightcraft' and advanced spacecraft propulsion engines. The polymers POM and GAP have played an important role in experiments and liquid ablation fuels show great promise. Some applications use a laser system which is distant from the propelled object, for example, on another spacecraft, the Earth or a planet. Others use a laser that is part of the spacecraft propulsion system on the spacecraft. Propulsion is produced when an intense laser beam strikes a condensed matter surface and produces a vapor or plasma jet. The advantages of this idea are that exhaust velocity of the propulsion engine covers a broader range than is available from chemistry, that it can be varied to meet the instantaneous demands of the particular mission, and that practical realizations give lower mass and greater simplicity for a payload delivery system. We review the underlying theory, buttressed by extensive experimental data. The primary problem in laser space propulsion theory has been the absence of a way to predict thrust and specific impulse over the transition from the vapor to the plasma regimes. We briefly discuss a method for combining two new vapor regime treatments with plasma regime theory, giving a smooth transition from one regime to the other. We conclude with a section on future directions.

  2. Laser ablation with applied magnetic field for electric propulsion

    Science.gov (United States)

    Batishcheva, Alla; Batishchev, Oleg; Cambier, Jean-Luc

    2012-10-01

    Using ultrafast lasers with tera-watt-level power allows efficient ablation and ionization of solid-density materials [1], creating dense and hot (˜100eV) plasma. We propose ablating small droplets in the magnetic nozzle configurations similar to mini-helicon plasma source [2]. Such approach may improve the momentum coupling compared to ablation of solid surfaces and facilitate plasma detachment. Results of 2D modeling of solid wire ablation in the applied magnetic field are presented and discussed. [4pt] [1] O. Batishchev et al, Ultrafast Laser Ablation for Space Propulsion, AIAA technical paper 2008-5294, -16p, 44th JPC, Hartford, 2008.[0pt] [2] O. Batishchev and J.L. Cambier, Experimental Study of the Mini-Helicon Thruster, Air Force Research Laboratory Report, AFRL-RZ-ED-TR-2009-0020, 2009.

  3. Ablation of Liquids for Laser Propulsion with TEA CO2 Laser

    National Research Council Canada - National Science Library

    Sinko, John; Kodgis, Lisa; Porter, Simon; Sterling, Enrique; Lin, Jun; Pakhomov, Andrew V; Larson, C. W; Mead, Jr, Franklin B

    2005-01-01

    .... A Transversely Excited at Atmospheric pressure (TEA) CO2 laser operated at 10.6 micro-m, 300 ns pulse width, and 9 J pulse energy was used to ablate liquids contained in various aluminum and glass vessels...

  4. Ablation of Liquids for Laser Propulsion With TEA CO2 Laser

    National Research Council Canada - National Science Library

    Sinko, John; Kodgis, Lisa; Porter, Simon; Sterling, Enrique; Lin, Jun; Pakhomov, Andrew V; Larson, C. W; Mead, Jr., Franklin B

    2005-01-01

    .... A Transversely Excited at Atmospheric pressure (TEA) CO2 laser operated at 10.6 um, 300 ns pulse width, and 9 J pulse energy was used to ablate liquids contained in various aluminum and glass vessels...

  5. Power Laser Ablation Symposia

    CERN Document Server

    Phipps, Claude

    2007-01-01

    Laser ablation describes the interaction of intense optical fields with matter, in which atoms are selectively driven off by thermal or nonthermal mechanisms. The field of laser ablation physics is advancing so rapidly that its principal results are seen only in specialized journals and conferences. This is the first book that combines the most recent results in this rapidly advancing field with authoritative treatment of laser ablation and its applications, including the physics of high-power laser-matter interaction. Many practical applications exist, ranging from inertial confinement fusion to propulsion of aerostats for pollution monitoring to laser ignition of hypersonic engines to laser cleaning nanoscale contaminants in high-volume computer hard drive manufacture to direct observation of the electronic or dissociative states in atoms and molecules, to studying the properties of materials during 200kbar shocks developed in 200fs. Selecting topics which are representative of such a broad field is difficu...

  6. Laser ablation principles and applications

    CERN Document Server

    1994-01-01

    Laser Ablation provides a broad picture of the current understanding of laser ablation and its many applications, from the views of key contributors to the field. Discussed are in detail the electronic processes in laser ablation of semiconductors and insulators, the post-ionization of laser-desorbed biomolecules, Fourier-transform mass spectroscopy, the interaction of laser radiation with organic polymers, laser ablation and optical surface damage, laser desorption/ablation with laser detection, and laser ablation of superconducting thin films.

  7. Laser ablation studies in southern Africa

    Science.gov (United States)

    McKenzie, Edric; Forbes, A.; Turner, G. R.; Michaelis, Max M.

    2000-08-01

    With the launch of the South African National Laser Centre, new programs will need to be defined. Medical, environmental and industrial laser applications must obviously take top priority -- as opposed to the uranium isotope separation and military applications of the past. We argue however, that a small effort in laser ablation for space propulsion is justifiable, since a few very large CO2 lasers are available and since two tentative propulsion experiments have already been conducted in South Africa. We attempt to give LISP (Laser Impulse Space Propulsion) an equatorial and a Southern dimension.

  8. Laser propulsion: a review

    CSIR Research Space (South Africa)

    Michaelis, MM

    2006-07-01

    Full Text Available -of-magnitude reduction in launch costs. American, German and Japanese experimental ‘lightcraft’ are described as well as the Orion programme to de-orbit space debris. Marx’s seminal paper on laser-driven, relativistic space propulsion and the ensuing controversy was also...

  9. Modeling CO2 Laser Ablative Impulse with Polymers

    International Nuclear Information System (INIS)

    Sinko, John E.; Phipps, Claude R.; Sasoh, Akihiro

    2010-01-01

    Laser ablation vaporization models have usually ignored the spatial dependence of the laser beam. Here, we consider effects from modeling using a Gaussian beam for both photochemical and photothermal conditions. The modeling results are compared to experimental and literature data for CO 2 laser ablation of the polymer polyoxymethylene under vacuum, and discussed in terms of the ablated mass areal density and momentum coupling coefficient. Extending the scope of discussion, laser ablative impulse generation research has lacked a cohesive strategy for linking the vaporization and plasma regimes. Existing models, mostly formulated for ultraviolet laser systems or metal targets, appear to be inappropriate or impractical for applications requiring CO 2 laser ablation of polymers. A recently proposed method for linking the vaporization and plasma regimes for analytical modeling is addressed here along with the implications of its use. Key control parameters are considered, along with the major propulsion parameters needed for laser ablation propulsion modeling.

  10. Laser propulsion of microelectronic components: releasing mechanism investigation

    NARCIS (Netherlands)

    Karlitskaya, N.; Meijer, J.; de Lange, D.F.; Kettelarij, Henk; Phipps, Claude R.

    2006-01-01

    Laser propulsion has gained increasing attention in the recent years. Ultra-high average power laser systems have emerged and found applications in launching satellites to the space. The impulse generated by ablation can also be used to move small parts. This article describes laser-induced

  11. Field enhancement induced laser ablation

    DEFF Research Database (Denmark)

    Fiutowski, Jacek; Maibohm, Christian; Kjelstrup-Hansen, Jakob

    Sub-diffraction spatially resolved, quantitative mapping of strongly localized field intensity enhancement on gold nanostructures via laser ablation of polymer thin films is reported. Illumination using a femtosecond laser scanning microscope excites surface plasmons in the nanostructures....... The accompanying field enhancement substantially lowers the ablation threshold of the polymer film and thus creates local ablation spots and corresponding topographic modifications of the polymer film. Such modifications are quantified straightforwardly via scanning electron and atomic force microscopy. Thickness...

  12. NASA's laser-propulsion project

    Science.gov (United States)

    Jones, L. W.; Keefer, D. R.

    1982-01-01

    Design concepts, study results, and research directions toward development of CW laser heating of remotely flying spacecraft fuels to provide high impulse thrust are presented. The incident laser radiation would be absorbed by hydrogen through a medium of a laser-supported plasma. The laser energy could be furnished from an orbiting solar-powered laser platform and used to drive the engines of an orbital transfer vehicle (OTV) at costs less than with a chemical propulsion system. The OTV propulsion chamber would be reduced in size comparable to the volume addition of the incident laser energy absorber. The temperatures in the hydrogen-fueled system could reach 5000-15,000 K, and studies have been done to examine the feasibility of ion-electron recombination. Kinetic performance, temperature field, and power necessary to sustain a laser thrust augmented system modeling results are discussed, along with near-term 30 kW CO2 laser system tests.

  13. Aerospace Laser Ignition/Ablation Variable High Precision Thruster

    Science.gov (United States)

    Campbell, Jonathan W. (Inventor); Edwards, David L. (Inventor); Campbell, Jason J. (Inventor)

    2015-01-01

    A laser ignition/ablation propulsion system that captures the advantages of both liquid and solid propulsion. A reel system is used to move a propellant tape containing a plurality of propellant material targets through an ignition chamber. When a propellant target is in the ignition chamber, a laser beam from a laser positioned above the ignition chamber strikes the propellant target, igniting the propellant material and resulting in a thrust impulse. The propellant tape is advanced, carrying another propellant target into the ignition chamber. The propellant tape and ignition chamber are designed to ensure that each ignition event is isolated from the remaining propellant targets. Thrust and specific impulse may by precisely controlled by varying the synchronized propellant tape/laser speed. The laser ignition/ablation propulsion system may be scaled for use in small and large applications.

  14. Laser Ablation for Medical Applications

    Science.gov (United States)

    Hayashi, Ken-Ichi

    Medical applications of laser are measurement, laser surgery, in-situ monitoring, and processing of medical devices. In this paper, author briefly reviews the trends of medical applications, describes some new applications, and then discuss about the future trends and problems of medical applications. At present, the domestic market of laser equipment for medical applications is nearly 1/10 of that for industrial applications, which has registered significant growth continuously. Laser surgery as a minimum invasive surgery under arthroscope is expected to decrease the pain of patients. Precise processing such as cutting and welding is suitable for manufacturing medical devices. Pulsed laser deposition has been successfully applied to the thin film coating. The corneal refractive surgery by ArF excimer laser has been widely accepted for its highly safe operation. Laser ablation for retinal implant in the visual prosthesis is one of the promising applications of laser ablation in medicine. New applications with femtosecond laser are expected in the near future.

  15. Power-law scaling of plasma pressure on laser-ablated tin microdroplets

    NARCIS (Netherlands)

    Kurilovich, Dmitry; Basko, Mikhail M.; Kim, Dmitrii A.; Torretti, Francesco; Schupp, Ruben; Visschers, Jim C.; Scheers, Joris; Hoekstra, Ronnie; Ubachs, Wim; Versolato, Oscar O.

    The measurement of the propulsion of metallic microdroplets exposed to nanosecond laser pulses provides an elegant method for probing the ablation pressure in a dense laser-produced plasma. We present the measurements of the propulsion velocity over three decades in the driving Nd:YAG laser pulse

  16. Laser Diagnostics for Spacecraft Propulsion

    Science.gov (United States)

    MacDonald-Tenenbaum, Natalia

    2015-09-01

    Over the past several decades, a variety of laser diagnostic techniques have been developed and applied to diagnose spacecraft propulsion devices. Laser diagnostics are inherently non-intrusive, and provide the opportunity to probe properties such as temperature, concentration or number density of plume species, and plume velocities in the harsh environments of combustion and plasma discharges. This presentation provides an overview of laser diagnostic capabilities for spacecraft propulsion devices such as small monopropellant thrusters, arcjets, ion engines and Hall thrusters. Particular emphasis is placed on recent developments for time-resolved ion velocity measurements in Hall thruster plumes. Results are presented for one such diagnostic method, a time-synchronized CW-laser induced fluorescence (LIF) technique based on a sample hold scheme. This method is capable of correlating measured fluorescence excitation lineshapes with high frequency current fluctuations in the plasma discharge of a Hall thruster and is tolerant of natural drifting in the current oscillation frequency.

  17. Femtosecond laser ablation of dentin

    Science.gov (United States)

    Alves, S.; Oliveira, V.; Vilar, R.

    2012-06-01

    The surface morphology, structure and composition of human dentin treated with a femtosecond infrared laser (pulse duration 500 fs, wavelength 1030 nm, fluences ranging from 1 to 3 J cm-2) was studied by scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The average dentin ablation threshold under these conditions was 0.6 ± 0.2 J cm-2 and the ablation rate achieved in the range 1 to 2 µm/pulse for an average fluence of 3 J cm-2. The ablation surfaces present an irregular and rugged appearance, with no significant traces of melting, deformation, cracking or carbonization. The smear layer was entirely removed by the laser treatment. For fluences only slightly higher than the ablation threshold the morphology of the laser-treated surfaces was very similar to the dentin fracture surfaces and the dentinal tubules remained open. For higher fluences, the surface was more porous and the dentin structure was partially concealed by ablation debris and a few resolidified droplets. Independently on the laser processing parameters and laser processing method used no sub-superficial cracking was observed. The dentin constitution and chemical composition was not significantly modified by the laser treatment in the processing parameter range used. In particular, the organic matter is not preferentially removed from the surface and no traces of high temperature phosphates, such as the β-tricalcium phosphate, were observed. The achieved results are compatible with an electrostatic ablation mechanism. In conclusion, the high beam quality and short pulse duration of the ultrafast laser used should allow the accurate preparation of cavities, with negligible damage of the underlying material.

  18. Femtosecond laser ablation of dentin

    International Nuclear Information System (INIS)

    Alves, S; Vilar, R; Oliveira, V

    2012-01-01

    The surface morphology, structure and composition of human dentin treated with a femtosecond infrared laser (pulse duration 500 fs, wavelength 1030 nm, fluences ranging from 1 to 3 J cm -2 ) was studied by scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The average dentin ablation threshold under these conditions was 0.6 ± 0.2 J cm -2 and the ablation rate achieved in the range 1 to 2 µm/pulse for an average fluence of 3 J cm -2 . The ablation surfaces present an irregular and rugged appearance, with no significant traces of melting, deformation, cracking or carbonization. The smear layer was entirely removed by the laser treatment. For fluences only slightly higher than the ablation threshold the morphology of the laser-treated surfaces was very similar to the dentin fracture surfaces and the dentinal tubules remained open. For higher fluences, the surface was more porous and the dentin structure was partially concealed by ablation debris and a few resolidified droplets. Independently on the laser processing parameters and laser processing method used no sub-superficial cracking was observed. The dentin constitution and chemical composition was not significantly modified by the laser treatment in the processing parameter range used. In particular, the organic matter is not preferentially removed from the surface and no traces of high temperature phosphates, such as the β-tricalcium phosphate, were observed. The achieved results are compatible with an electrostatic ablation mechanism. In conclusion, the high beam quality and short pulse duration of the ultrafast laser used should allow the accurate preparation of cavities, with negligible damage of the underlying material. (paper)

  19. Fractional ablative erbium YAG laser

    DEFF Research Database (Denmark)

    Taudorf, Elisabeth H; Haak, Christina S; Erlendsson, Andrés M

    2014-01-01

    BACKGROUND AND OBJECTIVES: Treatment of a variety of skin disorders with ablative fractional lasers (AFXL) is driving the development of portable AFXLs. This study measures micropore dimensions produced by a small 2,940 nm AFXL using a variety of stacked pulses, and determines a model correlating...... energies of 2.3-12.8 mJ/microbeam and total energy levels of 4.6-640 mJ/microchannel. Histological endpoints were ablation depth (AD), coagulation zone (CZ) and ablation width (AW). Data were logarithmically transformed if required prior to linear regression analyses. Results for histological endpoints...

  20. A Conceptual Tree of Laser Propulsion

    International Nuclear Information System (INIS)

    Pakhomov, Andrew V.; Sinko, John E.

    2008-01-01

    An original attempt to develop a conceptual tree for laser propulsion is offered. The tree provides a systematic view for practically all possible laser propulsion concepts and all inter-conceptual links, based on propellant phases and phase transfers. It also helps to see which fields of laser propulsion have been already thoroughly explored, where the next effort must be applied, and which paths should be taken with proper care or avoided entirely

  1. Brief review on pulse laser propulsion

    Science.gov (United States)

    Yu, Haichao; Li, Hanyang; Wang, Yan; Cui, Lugui; Liu, Shuangqiang; Yang, Jun

    2018-03-01

    Pulse laser propulsion (PLP) is an advanced propulsion concept can be used across a variety of fields with a wide range of applications. PLP reflects superior payload as well as decreased launch costs in comparison with other conventional methods of producing thrust, such as chemical propulsion or electric propulsion. Numerous researchers have attempted to exploit the potential applications of PLP. This paper first reviews concepts relevant to PLP, including the propulsion modes, breakdown regimes, and propulsion efficiency; the propulsion targets for different materials with the pulse laser are then discussed in detail, including the propulsion of solid and liquid microspheres. PLP applications such as the driven microsatellite, target surface particle removal, and orbital debris removal are also discussed. Although the PLP has been applied to a variety of fields, further research is yet warranted to establish its application in the aerospace field.

  2. Advances in laser ablation of materials

    International Nuclear Information System (INIS)

    Singh, R.K.; Lowndes, D.H.; Chrisey, D.B.; Fogarassy, E.; Narayan, J.

    1998-01-01

    The symposium, Advances in Laser Ablation of Materials, was held at the 1998 MRS Spring Meeting in San Francisco, California. The papers in this symposium illustrate the advances in pulsed laser ablation for a wide variety of applications involving semiconductors, superconductors, metals, ceramics, and polymers. In particular, advances in the deposition of oxides and related materials are featured. Papers dealing with both fundamentals and the applications of laser ablation are presented. Topical areas include: fundamentals of ablation and growth; in situ diagnostics and nanoscale synthesis advances in laser ablation techniques; laser surface processing; pulsed laser deposition of ferroelectric, magnetic, superconducting and optoelectronic thin films; and pulsed laser deposition of carbon-based and polymeric materials. Sixty papers have been processed separately for inclusion on the data base

  3. Water spray assisted ultrashort laser pulse ablation

    International Nuclear Information System (INIS)

    Silvennoinen, M.; Kaakkunen, J.J.J.; Paivasaari, K.; Vahimaa, P.

    2013-01-01

    Highlights: ► We show the novel method to use multibeam processing with ultrashort pulses efficiently. ► Sprayed thin water layer on ablation zone enhances ablation rate and quality. ► In some cases this method also enables ablation of the deeper and straighter holes compared to ones made without the water layer. ► Method also makes possible to directly write features without the self-organizing structures. - Abstract: We have studied femtosecond ablation under sprayed thin water film and its influence and benefits compared with ablation in the air atmosphere. These have been studied in case of the hole and the groove ablation using IR femtosecond laser. Water enhances the ablation rate and in some situations it makes possible to ablate the holes with a higher aspect ratio. While ablating the grooves, the water spray allows using the high fluences without the generation of the self-organized structures.

  4. The ALP-PALS Project: optimal coupling for laser propulsion

    Science.gov (United States)

    Boody, F. P.; Badziak, J.; Eckel, H.-A.; Gammino, S.; Krása, J.; Láska, L.; Mezzasalma, A.; Pakhomov, A. J.; Parys, P.; Pfeifer, M.; Pisarczyk, T.; Rohlena, K.; Schall, W.; Torrisi, L.; Wołowski, J.

    2006-05-01

    Since the early 1970s ablative laser propulsion (ALP) has promised to revolutionize space travel by reducing the 30:1 propellant/payload ratio needed for near-earth orbit by up to a factor of 50, by leaving the power source on the ground. But the necessary sub-ns high average power lasers were not available. Dramatic recent progress in laser diodes for pumping solid-state lasers is changing that. Recent results from military laser weapons R&D programs, combined with progress on ceramic disk lasers, suddenly promise lasers powerful enough for automobile-size, if not space shuttle-size payloads, not only the 4 - 10 kg "microsatellites" foreseen just a few years ago. For ALP, the 1.6-μm Er:YAG laser resonantly pumped by InP diode lasers is especially promising. Prior coupling experiments have demonstrated adequate coupling coefficients and specific impulses, but were done with too long pulses and too low pulse energies. The properties of ions produced and the ablated surface were generally not measured but are necessary for understanding and modeling propulsion properties. ALP-PALS will realistically measure ALP parameters using the Prague Asterix Laser System (PALS) high power photodissociation iodine laser (λ = 1.315 μm, E L <=1 kJ, τ ~ 400 ps, beam diameter ~29 cm, flat beam profile) whose parameters match those required for application. PALS' 1.3-μm λ is a little short (vs. 1.53-1.72 μm) but is the closest available and PALS' 2ω / 3ω capability allows wavelength dependence to be studied.

  5. Fractional ablative erbium YAG laser

    DEFF Research Database (Denmark)

    Taudorf, Elisabeth H; Haak, Christina S; Erlendsson, Andrés M

    2014-01-01

    BACKGROUND AND OBJECTIVES: Treatment of a variety of skin disorders with ablative fractional lasers (AFXL) is driving the development of portable AFXLs. This study measures micropore dimensions produced by a small 2,940 nm AFXL using a variety of stacked pulses, and determines a model correlating...... laser parameters with tissue effects. MATERIALS AND METHODS: Ex vivo pig skin was exposed to a miniaturized 2,940 nm AFXL, spot size 225 µm, density 5%, power levels 1.15-2.22 W, pulse durations 50-225 microseconds, pulse repetition rates 100-500 Hz, and 2, 20, or 50 stacked pulses, resulting in pulse...... 190 to 347 µm. CONCLUSIONS: Pulse stacking with a small, low power 2,940 nm AFXL created reproducible shallow to deep micropores, and influenced micropore configuration. Mathematical modeling established relations between laser settings and micropore dimensions, which assists in choosing laser...

  6. Laser ablation of paint in nuclear industry

    International Nuclear Information System (INIS)

    Brygo, Francois; Semerok, Alexandre; Weulersse, Jean-Marc; Thro, Pierre-Yves; Oltra, Roland; Decobert, Guy

    2006-01-01

    Nuclear dismantling faces the challenge of paint removal on large surfaces of painted walls. The conventional methods for paint stripping on concrete walls are mainly based on mechanical grinder and lead to an important volume of aerosols and wastes. Laser ablation has been evaluated as a promising method for paint removal with a number of advantages. The method reduces considerably the waste volume as the removal of paint is selective. The ablated matter can be collected by aerosol aspiration/filtration. The automation of the process can provide a higher capacity of paint removal. Laser ablation of paint was under our extensive studies. Laser ablation with different nanosecond repetition rate lasers was comparatively studied to understand the ablation mechanisms, and to obtain the highest efficiency of paint removal. The investigations were made with three Q-Switched Nd:YAG lasers (λ = 532 nm and λ = 1.064 μm). The different pulse durations (5 ns and 100 ns) demonstrated the different ablation regimes. Ablation with long pulses (100 ns) provided the best removal efficiency while the short ones (5 ns) decreased the ablation threshold fluence. It was demonstrated that the pulse repetition rate increasing in the 20 Hz - 10 kHz range induced heat accumulation in the paint. It resulted in ablation efficiency increase with a large decrease in the ablation threshold fluence. Laser ablation in the 0 - 10 J / cm 2 fluence range was investigated. Various paints were under investigation to obtain the maximum efficiency of paint removal for each specific experimental case. The ejected matter recording with a high speed imaging system allows to analyse the laser-matter interaction. (authors)

  7. Introduction to Laser Ablation Video Supplement.

    Science.gov (United States)

    Barnett, Gene H; Sloan, Andrew E; Tatsui, Claudio E

    2018-04-01

    Laser ablation (also known as laser interstitial thermal therapy [LITT]) has emerged as an important new technology for treating various disorders of the brain and spine. As with any new or emerging technology, there is a learning curve for its optimal use, and video tutorials can be important learning tools to help bridge gaps in knowledge for those who wish to become more familiar with laser ablation. In this special supplement to Neurosurgical Focus, videos illustrate laser ablation's use in the treatment of epilepsy and failed radiosurgery, as well as technical aspects of performing these procedures in eloquent brain and in the spine. We hope that these videos will enable you to enhance your understanding of the evolving use of laser ablation for disorders of the brain or spine. It is the editors' sincere hope that this will be helpful either in your own practice or in determining whether to refer to a neurosurgical colleague experienced in this field.

  8. Laser ablation in analytical chemistry - A review

    Energy Technology Data Exchange (ETDEWEB)

    Russo, Richard E.; Mao, Xianglei; Liu, Haichen; Gonzalez, Jhanis; Mao, Samuel S.

    2001-10-10

    Laser ablation is becoming a dominant technology for direct solid sampling in analytical chemistry. Laser ablation refers to the process in which an intense burst of energy delivered by a short laser pulse is used to sample (remove a portion of) a material. The advantages of laser ablation chemical analysis include direct characterization of solids, no chemical procedures for dissolution, reduced risk of contamination or sample loss, analysis of very small samples not separable for solution analysis, and determination of spatial distributions of elemental composition. This review describes recent research to understand and utilize laser ablation for direct solid sampling, with emphasis on sample introduction to an inductively coupled plasma (ICP). Current research related to contemporary experimental systems, calibration and optimization, and fractionation is discussed, with a summary of applications in several areas.

  9. Selective Laser Ablation and Melting, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — In this project Advratech will develop a new additive manufacturing (AM) process called Selective Laser Ablation and Melting (SLAM). The key innovation in this...

  10. Efficient Laser Ablation - Project AOARD 044033

    National Research Council Canada - National Science Library

    Uchida, Shigeaki

    2006-01-01

    .... The advantages of using laser is that it can avoid use of explosive or toxic oxidizing chemicals and eliminate the necessity of high voltage power supply that is for electrical propulsion systems...

  11. Laser Ablation of Biological Tissue Using Pulsed CO2 Laser

    International Nuclear Information System (INIS)

    Hashishin, Yuichi; Sano, Shu; Nakayama, Takeyoshi

    2010-01-01

    Laser scalpels are currently used as a form of laser treatment. However, their ablation mechanism has not been clarified because laser excision of biological tissue occurs over a short time scale. Biological tissue ablation generates sound (laser-induced sound). This study seeks to clarify the ablation mechanism. The state of the gelatin ablation was determined using a high-speed video camera and the power reduction of a He-Ne laser beam. The aim of this study was to clarify the laser ablation mechanism by observing laser excision using the high-speed video camera and monitoring the power reduction of the He-Ne laser beam. We simulated laser excision of a biological tissue by irradiating gelatin (10 wt%) with radiation from a pulsed CO 2 laser (wavelength: 10.6 μm; pulse width: 80 ns). In addition, a microphone was used to measure the laser-induced sound. The first pulse caused ablation particles to be emitted in all directions; these particles were subsequently damped so that they formed a mushroom cloud. Furthermore, water was initially evaporated by laser irradiation and then tissue was ejected.

  12. Chemically assisted laser ablation ICP mass spectrometry.

    Science.gov (United States)

    Hirata, Takafumi

    2003-01-15

    A new laser ablation technique combined with a chemical evaporation reaction has been developed for elemental ratio analysis of solid samples using an inductively coupled plasma mass spectrometer (ICPMS). Using a chemically assisted laser ablation (CIA) technique developed in this study, analytical repeatability of the elemental ratio measurement was successively improved. To evaluate the reliability of the CLA-ICPMS technique, Pb/U isotopic ratios were determined for zircon samples that have previously been analyzed by other techniques. Conventional laser ablation for Pb/U shows a serious elemental fractionation during ablation mainly due to the large difference in elemental volatility between Pb and U. In the case of Pb/U ratio measurement, a Freon R-134a gas (1,1,1,2-tetrafluoroethane) was introduced into the laser cell as a fluorination reactant. The Freon gas introduced into the laser cell reacts with the ablated sample U, and refractory U compounds are converted to a volatile U fluoride compound (UF6) under the high-temperature condition at the ablation site. This avoids the redeposition of U around the ablation pits. Although not all the U is reacted with Freon, formation of volatile UF compounds improves the transmission efficiency of U. Typical precision of the 206Pb/238U ratio measurement is 3-5% (2sigma) for NIST SRM 610 and Nancy 91500 zircon standard, and the U-Pb age data obtained here show good agreement within analytical uncertainties with the previously reported values. Since the observed Pb/U ratio for solid samples is relatively insensitive to laser power and ablation time, optimization of ablation conditions or acquisition parameters no longer needs to be performed on a sample-to-sample basis.

  13. Laser propulsion activity in South Africa

    CSIR Research Space (South Africa)

    Michaelis, MM

    2006-07-01

    Full Text Available projectiles reportedly ‘hit the roof’ some 10 metres high. Unfortunately, no momentum coupling constants were available, nor was there any time to take measurements. As to HF laser propulsion, only a rudimentary single-shot pendulum test was performed... together with a propulsion demonstration with a small plastic target. The reason for report- ing this is that HF LP or DF (deuterium fluoride) LP was the first type envisaged2 but has never been developed even in the laboratory. The South African HF...

  14. Review: laser ignition for aerospace propulsion

    Directory of Open Access Journals (Sweden)

    Steven A. O’Briant

    2016-03-01

    This paper aims to provide the reader an overview of advanced ignition methods, with an emphasis on laser ignition and its applications to aerospace propulsion. A comprehensive review of advanced ignition systems in aerospace applications is performed. This includes studies on gas turbine applications, ramjet and scramjet systems, and space and rocket applications. A brief overview of ignition and laser ignition phenomena is also provided in earlier sections of the report. Throughout the reading, research papers, which were presented at the 2nd Laser Ignition Conference in April 2014, are mentioned to indicate the vast array of projects that are currently being pursued.

  15. Femtosecond laser ablation of carbon reinforced polymers

    International Nuclear Information System (INIS)

    Moreno, P.; Mendez, C.; Garcia, A.; Arias, I.; Roso, L.

    2006-01-01

    Interaction of intense ultrashort laser pulses (120 fs at 795 nm) with polymer based composites has been investigated. We have found that carbon filled polymers exhibit different ultrafast ablation behaviour depending on whether the filling material is carbon black or carbon fiber and on the polymer matrix itself. The shape and dimensions of the filling material are responsible for some geometrical bad quality effects in the entrance and inner surfaces of drilled microholes. We give an explanation for these non-quality effects in terms of fundamentals of ultrafast ablation process, specifically threshold laser fluences and material removal paths. Since carbon fiber reinforced polymers seemed particularly concerned, this could prevent the use of ultrafast ablation for microprocessing purposes of some of these materials

  16. Laser systems for ablative fractional resurfacing

    DEFF Research Database (Denmark)

    Paasch, Uwe; Haedersdal, Merete

    2011-01-01

    ablative laser systems. Fractionated CO(2) (10,600-nm), erbium yttrium aluminum garnet, 2940-nm and yttrium scandium gallium garnet, 2790-nm lasers are available. In this article, we present an overview of AFR technology, devices and histopathology, and we summarize the current clinical possibilities...... with AFR incorporating our personal experience. AFR is still in the exploratory era, and systematic investigations of clinical outcomes related to various system settings are needed....

  17. Bending diamonds by femtosecond laser ablation

    DEFF Research Database (Denmark)

    Balling, Peter; Esberg, Jakob; Kirsebom, Kim

    2009-01-01

    We present a new method based on femtosecond laser ablation for the fabrication of statically bent diamond crystals. Using this method, curvature radii of 1 m can easily be achieved, and the curvature obtained is very uniform. Since diamond is extremely tolerant to high radiation doses, partly due...

  18. Diagnostics of laser ablated plasma plumes

    DEFF Research Database (Denmark)

    Amoruso, S.; Toftmann, B.; Schou, Jørgen

    2004-01-01

    emission spectroscopy. Second, deposition rate and fast ion probe measurements have been used to study the plume propagation dynamics during laser ablation of a silver target, over a large range of Ar background gas pressures (from high vacuum to approximate to 100 Pa). A comparative analysis...

  19. Picosecond laser ablation of porcine sclera

    Science.gov (United States)

    Góra, Wojciech S.; Harvey, Eleanor M.; Dhillon, Baljean; Parson, Simon H.; Maier, Robert R. J.; Hand, Duncan P.; Shephard, Jonathan D.

    2013-03-01

    Lasers have been shown to be successful in certain medical procedures and they have been identified as potentially making a major contribution to the development of minimally invasive procedures. However, the uptake is not as widespread and there is scope for many other applications where laser devices may offer a significant advantage in comparison to the traditional surgical tools. The purpose of this research is to assess the potential of using a picosecond laser for minimally invasive laser sclerostomy. Experiments were carried out on porcine scleral samples due to the comparable properties to human tissue. Samples were prepared with a 5mm diameter trephine and were stored in lactated Ringer's solution. After laser machining, the samples were fixed in 3% glutaraldehyde, then dried and investigated under SEM. The laser used in the experiments is an industrial picosecond TRUMPF TruMicro laser operating at a wavelength of 1030nm, pulse length of 6ps, repetition rate of 1 kHz and a focused spot diameter of 30μm. The laser beam was scanned across the samples with the use of a galvanometer scan head and various ablation patterns were investigated. Processing parameters (pulse energy, spot and line separation) which allow for the most efficient laser ablation of scleral tissue without introducing any collateral damage were investigated. The potential to create various shapes, such as linear incisions, square cavities and circular cavities was demonstrated.

  20. Ablation characteristics of carbon-doped glycerol irradiated by a 1064 nm nanosecond pulse laser

    Science.gov (United States)

    Jing, QI; Siqi, ZHANG; Tian, LIANG; Ke, XIAO; Weichong, TANG; Zhiyuan, ZHENG

    2018-03-01

    The ablation characteristics of carbon-doped glycerol were investigated in laser plasma propulsion using a pulse laser with 10 ns pulse width and 1064 nm wavelength. The results showed that with the incident laser intensity increasing, the target momentum decreased. Results still indicated that the strong plasma shielded the consumption loss and resulted in a low coupling coefficient. Furthermore, the carbon-doping gave rise to variations in the laser focal position and laser intensity, which in turn reduced the glycerol splashing. Based on the glycerol viscosity and the carbon doping, a high specific impulse is anticipated.

  1. Laser Plasmas: Plasma dynamics from laser ablated solid lithium

    Indian Academy of Sciences (India)

    Emission plasma plume generated by pulsed laser ablation of a lithium solid target by a ruby laser (694 nm, 20 ns, 3 J) was subjected to optical emission spectroscopy: time and space resolved optical emission was characterised as a function of distance from the target surface. Propagation of the plume was studied through ...

  2. Laser systems for ablative fractional resurfacing

    DEFF Research Database (Denmark)

    Paasch, Uwe; Haedersdal, Merete

    2011-01-01

    Ablative fractional resurfacing (AFR) creates microscopic vertical ablated channels that are surrounded by a thin layer of coagulated tissue, constituting the microscopic treatment zones (MTZs). AFR induces epidermal and dermal remodeling, which raises new possibilities for the treatment...... of a variety of skin conditions, primarily chronically photodamaged skin, but also acne and burn scars. In addition, it is anticipated that AFR can be utilized in the laser-assisted delivery of topical drugs. Clinical efficacy coupled with minimal downtime has driven the development of various fractional...

  3. Laser systems for ablative fractional resurfacing

    DEFF Research Database (Denmark)

    Paasch, Uwe; Haedersdal, Merete

    2011-01-01

    ablative laser systems. Fractionated CO(2) (10,600-nm), erbium yttrium aluminum garnet, 2940-nm and yttrium scandium gallium garnet, 2790-nm lasers are available. In this article, we present an overview of AFR technology, devices and histopathology, and we summarize the current clinical possibilities...... of a variety of skin conditions, primarily chronically photodamaged skin, but also acne and burn scars. In addition, it is anticipated that AFR can be utilized in the laser-assisted delivery of topical drugs. Clinical efficacy coupled with minimal downtime has driven the development of various fractional...

  4. Laser ablation comparison by picosecond pulses train and nanosecond pulse

    Science.gov (United States)

    Lednev, V. N.; Filippov, M. N.; Bunkin, A. F.; Pershin, S. M.

    2015-12-01

    A comparison of laser ablation by a train of picosecond pulses and nanosecond pulses revealed a difference in laser craters, ablation thresholds, plasma sizes and spectral line intensities. Laser ablation with a train of picosecond pulses resulted in improved crater quality while ablated mass decreased up to 30%. A reduction in laser plasma dimensions for picosecond train ablation was observed while the intensity of atomic/ionic lines in the plasma spectra was greater by a factor of 2-4 indicating an improved excitation and atomization in the plasma.

  5. Subcellular analysis by laser ablation electrospray ionization mass spectrometry

    Science.gov (United States)

    Vertes, Akos; Stolee, Jessica A; Shrestha, Bindesh

    2014-12-02

    In various embodiments, a method of laser ablation electrospray ionization mass spectrometry (LAESI-MS) may generally comprise micro-dissecting a cell comprising at least one of a cell wall and a cell membrane to expose at least one subcellular component therein, ablating the at least one subcellular component by an infrared laser pulse to form an ablation plume, intercepting the ablation plume by an electrospray plume to form ions, and detecting the ions by mass spectrometry.

  6. Ablation of polymers by ultraviolet pulsed laser

    International Nuclear Information System (INIS)

    Brezini, A.; Benharrats, N.

    1993-08-01

    The surface modifications of different polymers treated by far UV-Excimer laser (λ = 193mn, 248, 308nm) are analysed by X-Ray Photoelectrons Spectroscopy. The main feature observed depends strongly on the absorption coefficients. For the high absorbing polymers such (PVC, PS, PI,...) the mechanism of the UV-Excimer Laser interaction appears to be governed by an ablative photodecomposition process (APD) with an APD threshold. In the other limit, i.e. low absorbing polymer the interaction leads to a photothermal process. (author). 51 refs, 24 figs, 7 tabs

  7. Laser ablation of the protein lysozyme

    DEFF Research Database (Denmark)

    Schou, Jørgen; Canulescu, Stela; Amoruso, Salvatore

    Lysozyme is a well-known protein, which is used in food processing because of its bactericidal properties. The mass (14307 amu) is in the range in which it easily can be monitored by mass spectrometric methods, for example by MALDI (Matrix assisted laser desorption ionization). We have recently...... to a substrate as intact molecules by the violent laser impact ( up to 50 mJ/pulse) has not yet been understood. One issue is that up to 150 ng/pulse is removed by the laser, and much of the material is ejected from the target in relatively large chunks. We have explored as well the excitation mechanics by laser...... impact. Samples of pressed lysozyme prepared in the same manner as in ns-experiments have been irradiated at 527 nm with >>300-fs pulses and at a similar fluence as in ns ablation. Even though the pulse energy was much smaller, there was a considerable ablation weight loss of lysozyme from each shot...

  8. Pulsed laser ablation of solids basics, theory and applications

    CERN Document Server

    Stafe, Mihai; Puscas, Niculae N

    2014-01-01

    The book introduces ‘the state of the art' of pulsed laser ablation and its applications. It is based on recent theoretical and experimental studies. The book reaches from the basics to advanced topics of pulsed laser ablation. Theoretical and experimental fundamental phenomena involved in pulsed laser ablation are discussed with respect to material properties, laser wavelength, fluence and intensity regime of the light absorbed linearly or non-linearly in the target material. The energy absorbed by the electrons leads to atom/molecule excitation, ionization and/or direct chemical bond breaking and is also transferred to the lattice leading to material heating and phase transitions. Experimental  non-invasive optical methods for analyzing these phenomena in real time are described. Theoretical models for pulsed laser ablation and phase transitions induced by laser beams and laser-vapour/plasma interaction during the plume expansion above the target are also presented. Calculations of the ablation speed and...

  9. Ablation mass features in multi-pulses femtosecond laser ablate molybdenum target

    Science.gov (United States)

    Zhao, Dongye; Gierse, Niels; Wegner, Julian; Pretzler, Georg; Oelmann, Jannis; Brezinsek, Sebastijan; Liang, Yunfeng; Neubauer, Olaf; Rasinski, Marcin; Linsmeier, Christian; Ding, Hongbin

    2018-03-01

    In this study, the ablation mass features related to reflectivity of bulk Molybdenum (Mo) were investigated by a Ti: Sa 6 fs laser pulse at central wavelength 790 nm. The ablated mass removal was determined using Confocal Microscopy (CM) technique. The surface reflectivity was calibrated and measured by a Lambda 950 spectrophotometer as well as a CCD camera during laser ablation. The ablation mass loss per pulse increase with the increasing of laser shots, meanwhile the surface reflectivity decrease. The multi-pulses (100 shots) ablation threshold of Mo was determined to be 0.15 J/cm2. The incubation coefficient was estimated as 0.835. The reflectivity change of the Mo target surface following multi-pulses laser ablation were studied as a function of laser ablation shots at various laser fluences from 1.07 J/cm2 to 36.23 J/cm2. The results of measured reflectivity indicate that surface reflectivity of Mo target has a significant decline in the first 3-laser pulses at the various fluences. These results are important for developing a quantitative analysis model for laser induced ablation and laser induced breakdown spectroscopy for the first wall diagnosis of EAST tokamak.

  10. Laser-supported detonation waves and pulsed laser propulsion

    International Nuclear Information System (INIS)

    Kare, J.

    1990-01-01

    A laser thermal rocket uses the energy of a large remote laser, possibly ground-based, to heat an inert propellant and generate thrust. Use of a pulsed laser allows the design of extremely simple thrusters with very high performance compared to chemical rockets. The temperatures, pressures, and fluxes involved in such thrusters (10 4 K, 10 2 atmospheres, 10 7 w/cm 2 ) typically result in the creation of laser-supported detonation (LSD) waves. The thrust cycle thus involves a complex set of transient shock phenomena, including laser-surface interactions in the ignition of the LSD wave, laser-plasma interactions in the LSD wave itself, and high-temperature nonequilibrium chemistry behind the LSD wave. The SDIO Laser Propulsion Program is investigating these phenomena as part of an overall effort to develop the technology for a low-cost Earth-to-orbit laser launch system. We will summarize the Program's approach to developing a high performance thruster, the double-pulse planar thruster, and present an overview of some results obtained to date, along with a discussion of the many research question still outstanding in this area

  11. CT Guided Laser Ablation of Osteoid Osteoma

    Directory of Open Access Journals (Sweden)

    Manohar Kachare

    2015-10-01

    Full Text Available To present our experience of Computed Tomography (CT guided laser ablation of radiologically proven osteoid osteoma in the inter trochantric region of the femur. A19 year old female presented with severe pain in left upper thigh region since 6-7 months, which was exaggerated during nights and was relived on taking oral Non Steroid Anti Inflammatory Drugs (NSAIDs. On CT scan hypodense lesion with surrounding dense sclerosis noted in intertrochanteric region in left femur. Magnetic Resonance Imaging (MRI revealed small focal predominantly cortical, oval lytic lesion in the intertrochanteric region which appeared hypointense on T1 Weighted Image (T1WI and hyperintense on T2 Weighted Image (T2WI and Short Tau Inversion Recovery (STIR image. Diffuse extensive sclerosis and hyperostosis of bone was noted surrounding the lesion appearing hypointense on T1W and T2W images. Under local anesthesia the laser fibre was inserted in the nidus under CT guidance through bone biopsy needle and 1800 joules energy delivered in the lesion continuous mode. Complete relief of pain noted after 24 hours after the treatment. CT guided LASER ablation is a safe, simple and effective method of treatment for osteoid osteoma.

  12. Obtention of Ti nanoparticles by laser ablation

    International Nuclear Information System (INIS)

    Diaz E, J.R.; Escobar A, L.; Camps, E.; Santiago, P.; Ascencio, J.

    2002-01-01

    The obtention of Ti nanoparticles around 5-30 nm diameter through the laser ablation technique is reported. The formation of nanoparticles is carried out in He atmosphere to different pressures, placing directly in Si substrates (100) and in Cu grids. The results show that the work pressure is an important parameter that allows to control the nanoparticles size. Also the plasma characterization results are presented where the Ti II is the predominant specie with an average kinetic energy of 1824 eV. (Author)

  13. Laser-driven hypersonic air-breathing propulsion simulator

    Science.gov (United States)

    Joshi, Prakash B.; Lo, Edmond Y.; Pugh, Evan R.

    1992-01-01

    A feasibility study is presented of simulating airbreathing propulsion on small scale hypersonic models using laser energy. The laser heat addition scheme allows simultaneous inlet and exhaust flows during wind tunnel testing of models with scramjet models. The proposed propulsion simulation concept has extended the Kantrowitz (1974) idea to propulsive wind tunnel models of hypersonic aircraft. Critical issues in aeropropulsive testing of models based on a ramjet power plant are addressed which include transfer of the correct amount of energy to the flowing gas, efficient absorption of laser energy into the gas, and test performance under tunnel reservoir conditions and at reasonable Reynolds numbers.

  14. Design and characterization of nozzles and solid propellants for IR laser propulsion

    Science.gov (United States)

    Toro, Cinthya; Gómez, Nicolás D.; Boggio, Norberto G.; Codnia, Jorge; Azcárate, M. Laura; Rinaldi, Carlos

    2014-10-01

    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.

  15. Topography-guided treatment of decentered laser ablation using LaserSight's excimer laser.

    Science.gov (United States)

    Wu, L; Zhou, X; Ouyang, Z; Weng, C; Chu, R

    2008-01-01

    To assess the efficacy of topography-guided laser ablation for correction of previously decentered laser ablation using LaserSight's excimer laser. Re-treatment was performed to correct decentered ablation using LaserSight's excimer laser for 18 patients who previously underwent LASIK surgery for myopia correction in both eyes. For each patient, only the decentered eye was re-treated while the other asymptomatic eye forms a control group for this study. Measurements were conducted on ablation center, best spectacle-corrected visual acuity (BSCVA), contrast sensitivity and corneal aberrations pre- and post-operatively. For the retreated 18 eyes, the mean decentration was significantly reduced from 1.32+/-0.28mm to 0.61+/-0.23mm post-operatively (t=16.24, pTopography-guided ablation with LaserSight excimer laser is effective to correct decentered ablation. However, the re-treated eye is still inferior to the eye with originally centered ablation in corneal optical quality or visual performance.

  16. Nanosecond pulsed laser ablation of silicon in liquids

    Energy Technology Data Exchange (ETDEWEB)

    Karimzadeh, R.; Anvari, J.Z.; Mansour, N. [Shahid Beheshti University, Department of Physics, Tehran (Iran)

    2009-03-15

    Laser fluence and laser shot number are important parameters for pulse laser based micromachining of silicon in liquids. This paper presents laser-induced ablation of silicon in liquids of the dimethyl sulfoxide (DMSO) and the water at different applied laser fluence levels and laser shot numbers. The experimental results are conducted using 15 ns pulsed laser irradiation at 532 nm. The silicon surface morphology of the irradiated spots has an appearance as one can see in porous formation. The surface morphology exhibits a large number of cavities which indicates as bubble nucleation sites. The observed surface morphology shows that the explosive melt expulsion could be a dominant process for the laser ablation of silicon in liquids using nanosecond pulsed laser irradiation at 532 nm. Silicon surface's ablated diameter growth was measured at different applied laser fluences and shot numbers in both liquid interfaces. A theoretical analysis suggested investigating silicon surface etching in liquid by intense multiple nanosecond laser pulses. It has been assumed that the nanosecond pulsed laser-induced silicon surface modification is due to the process of explosive melt expulsion under the action of the confined plasma-induced pressure or shock wave trapped between the silicon target and the overlying liquid. This analysis allows us to determine the effective lateral interaction zone of ablated solid target related to nanosecond pulsed laser illumination. The theoretical analysis is found in excellent agreement with the experimental measurements of silicon ablated diameter growth in the DMSO and the water interfaces. Multiple-shot laser ablation threshold of silicon is determined. Pulsed energy accumulation model is used to obtain the single-shot ablation threshold of silicon. The smaller ablation threshold value is found in the DMSO, and the incubation effect is also found to be absent. (orig.)

  17. Influence of ablation wavelength and time on optical properties of laser ablated carbon dots

    Science.gov (United States)

    Isnaeni, Hanna, M. Yusrul; Pambudi, A. A.; Murdaka, F. H.

    2017-01-01

    Carbon dots, which are unique and applicable materials, have been produced using many techniques. In this work, we have fabricated carbon dots made of coconut fiber using laser ablation technique. The purpose of this work is to evaluate two ablation parameters, which are ablation wavelength and ablation time. We used pulsed laser from Nd:YAG laser with emit wavelength at 355 nm, 532 nm and 1064 nm. We varied ablation time one hour and two hours. Photoluminescence and time-resolved photoluminescence setup were used to study the optical properties of fabricated carbon dots. In general, fabricated carbon dots emit bluish green color emission upon excitation by blue laser. We found that carbon dots fabricated using 1064 nm laser produced the highest carbon dots emission among other samples. The peak wavelength of carbon dots emission is between 495 nm until 505 nm, which gives bluish green color emission. Two hours fabricated carbon dots gave four times higher emission than one hour fabricated carbon dot. More emission intensity of carbon dots means more carbon dots nanoparticles were fabricated during laser ablation process. In addition, we also measured electron dynamics of carbon dots using time-resolved photoluminescence. We found that sample with higher emission has longer electron decay time. Our finding gives optimum condition of carbon dots fabrication from coconut fiber using laser ablation technique. Moreover, fabricated carbon dots are non-toxic nanoparticles that can be applied for health, bio-tagging and medical applications.

  18. Numerical Analysis of Beam Riding Performance for Laser Propulsion Vehicle

    OpenAIRE

    高橋, 聖幸; Takahashi, Masayuki; 大西, 直文; Onishi, Naofumi

    2012-01-01

    A beam riding performance is very important for a stable flight of a laser propulsion vehicle. We have developed a three-dimensional hydrodynamics code coupling with six-degree-of-freedom equation of motion of the laser propulsion vehicle for analyzing beam riding performance through numerical simulations of flowfield interacting with unsteady motion of the vehicle. An asymetric energy distribution was initially added around the focal spot (ring) in order to estimate the beam riding performan...

  19. Renaissance of laser interstitial thermal ablation.

    Science.gov (United States)

    Missios, Symeon; Bekelis, Kimon; Barnett, Gene H

    2015-03-01

    Laser interstitial thermal therapy (LITT) is a minimally invasive technique for treating intracranial tumors, originally introduced in 1983. Its use in neurosurgical procedures was historically limited by early technical difficulties related to the monitoring and control of the extent of thermal damage. The development of magnetic resonance thermography and its application to LITT have allowed for real-time thermal imaging and feedback control during laser energy delivery, allowing for precise and accurate provision of tissue hyperthermia. Improvements in laser probe design, surgical stereotactic targeting hardware, and computer monitoring software have accelerated acceptance and clinical utilization of LITT as a neurosurgical treatment alternative. Current commercially available LITT systems have been used for the treatment of neurosurgical soft-tissue lesions, including difficult to access brain tumors, malignant gliomas, and radiosurgery-resistant metastases, as well as for the ablation of such lesions as epileptogenic foci and radiation necrosis. In this review, the authors aim to critically analyze the literature to describe the advent of LITT as a neurosurgical, laser excision tool, including its development, use, indications, and efficacy as it relates to neurosurgical applications.

  20. Filamented plasmas in laser ablation of solids

    Science.gov (United States)

    Davies, J. R.; Fajardo, M.; Kozlová, M.; Mocek, T.; Polan, J.; Rus, B.

    2009-03-01

    We report results from laser-solid experiments at PALS using an x-ray laser probe with a pulse length of 0.1 ns and a wavelength of 21.2 nm. A laser with a pulse length of 0.3 ns, a peak intensity of up to 5 × 1013 W cm-2 and a wavelength of 1.3 µm was focused to a 0.15 mm wide line on 3 mm long zinc and 1 mm long iron targets and the probe was passed along the length of the plasma formed. The results show plasma 'hairs', or filaments, appearing only below the critical density, 0.1 ns before the peak of the laser pulse. The plasma around the critical density was clearly imaged and remained uniform. Magneto-hydrodynamic modelling indicates that this is caused by a magnetic field that diffuses from the critical surface, where it is generated, leading to a magnetic pressure comparable to the plasma pressure below the critical density. A dispersion relation is derived for density perturbations perpendicular to a temperature gradient in the presence of an existing magnetic field, which shows that such perturbations always grow, with the growth rate being the greatest for small wavelength perturbations and at low densities. These results indicate that the hair-like structures should be a typical feature of laser ablated plasmas below the critical density following significant plasma expansion, in agreement with numerous experimental results. The implications for x-ray lasers and fast ignition inertial confinement fusion are discussed.

  1. Plume collimation for laser ablation electrospray ionization mass spectrometry

    Science.gov (United States)

    Vertes, Akos; Stolee, Jessica A.

    2014-09-09

    In various embodiments, a device may generally comprise a capillary having a first end and a second end; a laser to emit energy at a sample in the capillary to ablate the sample and generate an ablation plume in the capillary; an electrospray apparatus to generate an electrospray plume to intercept the ablation plume to produce ions; and a mass spectrometer having an ion transfer inlet to capture the ions. The ablation plume may comprise a collimated ablation plume. The device may comprise a flow cytometer. Methods of making and using the same are also described.

  2. Laser-induced shockwave propagation from ablation in a cavity

    International Nuclear Information System (INIS)

    Zeng Xianzhong; Mao Xianglei; Mao, Samuel S.; Wen, S.-B.; Greif, Ralph; Russo, Richard E.

    2006-01-01

    The propagation of laser-induced shockwaves from ablation inside of cavities was determined from time-resolved shadowgraph images. The temperature and electron number density of the laser-induced plasma was determined from spectroscopic measurements. These properties were compared to those for laser ablation on the flat surface under the same energy and background gas condition. A theoretical model was proposed to determine the amount of energy and vaporized mass stored in the vapor plume based on these measurements

  3. Synthesis of Ag@Silica Nanoparticles by Assisted Laser Ablation

    OpenAIRE

    González-Castillo, JR; Rodriguez, E.; Jimenez-Villar, E.; Rodríguez, D.; Salomon-García, I.; de Sá, Gilberto F.; García-Fernández, T.; Almeida, DB; Cesar, CL; Johnes, R.; Ibarra, Juana C.

    2015-01-01

    This paper reports the synthesis of silver nanoparticles coated with porous silica (Ag@Silica NPs) using an assisted laser ablation method. This method is a chemical synthesis where one of the reagents (the reducer agent) is introduced in nanometer form by laser ablation of a solid target submerged in an aqueous solution. In a first step, a silicon wafer immersed in water solution was laser ablated for several minutes. Subsequently, an AgNO3 aliquot was added to the aqueous solution. The redo...

  4. Beamed Energy Propulsion by Means of Target Ablation

    International Nuclear Information System (INIS)

    Rosenberg, Benjamin A.

    2004-01-01

    This paper describes hundreds of pendulum tests examining the beamed energy conversion efficiency of different metal targets coated with multiple liquid enhancers. Preliminary testing used a local laser with photographic paper targets, with no liquid, water, canola oil, or methanol additives. Laboratory experimentation was completed at Wright-Patterson AFB using a high-powered laser, and ballistic pendulums of aluminum, titanium, or copper. Dry targets, and those coated with water, methanol and oil were repeatedly tested in laboratory conditions. Results were recorded on several high-speed digital video cameras, and the conversion efficiency was calculated. Paper airplanes successfully launched using BEP were likewise recorded

  5. Experimental studies of laser-ablated zirconium carbide plasma plumes: Fuel corrosion diagnostic development

    International Nuclear Information System (INIS)

    Wantuck, P.J.; Butt, D.P.; Sappey, A.D.

    1992-01-01

    Understanding the corrosion behavior of nuclear fuel materials, such as refractory carbides, in a high temperature hydrogen environment is critical for several proposed nuclear thermal propulsion (NTP) concepts. Monitoring the fuel corrosion products is important not only for understanding corrosion characteristics, but to assess the performance of an actual, operating nuclear propulsion system as well. In this paper, we describe an experimental study initiated to develop, test, and subsequently utilize non-intrusive, laser-based diagnostics to characterize the gaseous product species which are expected to evolve during the exposure of representative fuel samples to hydrogen. Laser ablation is used to produce high temperature, vapor plumes from solid solution, uranium-free, zirconium carbide (ZrC) forms for probing by other laser diagnostic methods; predominantly laser-induced fluorescence (LIF). We discuss the laser ablation technique, results of plume emission measurements, as well as the use of planar LIF to image both the ZrC plumes and actual NTP fuel corrosion constituents

  6. Laser tattoo removal with preceding ablative fractional treatment

    Science.gov (United States)

    Cencič, Boris; Možina, Janez; Jezeršek, Matija

    2013-06-01

    A combined laser tattoo removal treatment, first the ablative fractional resurfacing (AFR) with an Er:YAG laser and then the q-switched (QSW) Nd:YAG laser treatment, was studied. Experiments show that significantly higher fluences can be used for the same tissue damage levels.

  7. Use of laser ablation in nuclear decontamination

    International Nuclear Information System (INIS)

    Moggia, Fabrice; Lecardonnel, Xavier; Damerval, Frederique

    2012-09-01

    The development and the use of clean decontamination process appear to be one of the main priorities for industries especially for nuclear industries. This is especially due to the fact of wastes minimization which is one of the principal commitments. One answer would be to use a photonic process such as the LASER process. The principle of this process is based on the absorption, by the contaminant, of the photon's energy. This energy then will propagate into the material and create some mechanical waves responsible of the interfaces embrittlement and de-cohesion. As we can see, this process so called LASER ablation does not use any chemicals and allows us to avoid any production of liquid waste. Since now a couple of years, the Clean-Up Business Unit of AREVA group (BE/CL) investigates this new decontamination technology. Many tests have been done in inactive conditions on various simulants such as paints, inks, resins, metallic oxides firstly in order to estimate its efficiency but also to fully qualify it. After that, we decided to move on hot tests to fully validate this new process and to show its interest for the nuclear industry. Those hot tests have been done on two kinds of contaminated material (on tank pieces covered with a thick metallic oxide layer and on metallic pieces covered with grease). Some information such as Scanning Electron Microscopy (SEM), X-Ray scattering spectroscopy and decontamination factors (DF) will be provided in this paper. (authors)

  8. Laser ablation for the synthesis of carbon nanotubes

    Science.gov (United States)

    Holloway, Brian C.; Eklund, Peter C.; Smith, Michael W.; Jordan, Kevin C.; Shinn, Michelle

    2010-04-06

    Single walled carbon nanotubes are produced in a novel apparatus by the laser-induced ablation of moving carbon target. The laser used is of high average power and ultra-fast pulsing. According to various preferred embodiments, the laser produces an output above about 50 watts/cm.sup.2 at a repetition rate above about 15 MHz and exhibits a pulse duration below about 10 picoseconds. The carbon, carbon/catalyst target and the laser beam are moved relative to one another and a focused flow of "side pumped", preheated inert gas is introduced near the point of ablation to minimize or eliminate interference by the ablated plume by removal of the plume and introduction of new target area for incidence with the laser beam. When the target is moved relative to the laser beam, rotational or translational movement may be imparted thereto, but rotation of the target is preferred.

  9. Laser ablation for the synthesis of carbon nanotubes

    Science.gov (United States)

    Holloway, Brian C. (Inventor); Eklund, Peter C. (Inventor); Smith, Michael W. (Inventor); Jordan, Kevin C. (Inventor); Shinn, Michelle (Inventor)

    2012-01-01

    Single walled carbon nanotubes are produced in a novel apparatus by the laser-induced ablation of moving carbon target. The laser used is of high average power and ultra-fast pulsing. According to various preferred embodiments, the laser produces and output above about 50 watts/cm.sup.2 at a repetition rate above about 15 MHz and exhibits a pulse duration below about 10 picoseconds. The carbon, carbon/catalyst target and the laser beam are moved relative to one another and a focused flow of "side pumped", preheated inert gas is introduced near the point of ablation to minimize or eliminate interference by the ablated plume by removal of the plume and introduction of new target area for incidence with the laser beam. When the target is moved relative to the laser beam, rotational or translational movement may be imparted thereto, but rotation of the target is preferred.

  10. Preparation of antibacterial textile using laser ablation method

    Science.gov (United States)

    Shahidi, Sheila; Rashidian, M.; Dorranian, D.

    2018-02-01

    A facile in situ laser ablation synthesis of Copper nanoparticles on cotton fabric is reported in this paper. This synthetic method is a laser ablation based fabrication of Cu nanoparticles on cotton fabric for improved performance and antibacterial activity. The treated cotton fabric was characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, UV-Visible spectroscopic techniques and antibacterial counting test. Very good antibacterial behavior of treated fabrics achieved. This fabric can be used as medical and industrial textiles.

  11. The ALP-PALS project: optimal coupling for laser propulsion

    Czech Academy of Sciences Publication Activity Database

    Boody, F. P.; Badziak, J.; Eckel, H.A.; Gammino, S.; Krása, Josef; Láska, Leoš; Mezzasalma, A.; Pakhomov, A.J.; Parys, P.; Pfeifer, Miroslav; Rohlena, Karel; Schall, W.; Torrisi, L.; Wolowski, J.

    2005-01-01

    Roč. 160, 10-12 (2005), s. 525-533 ISSN 1042-0150. [Workshop PIBHI 2005 /2./. Giardini Naxos, 08.06.06-11.06.06] R&D Projects: GA MŠk(CZ) LC528 Institutional research plan: CEZ:AV0Z10100523 Keywords : laser space propultion * laser ablation * coupling coefficient * ion properties Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.353, year: 2005

  12. Development of laser ablation plasma by anisotropic self-radiation

    Directory of Open Access Journals (Sweden)

    Ohnishi Naofumi

    2013-11-01

    Full Text Available We have proposed a method for reproducing an accurate solution of low-density ablation plasma by properly treating anisotropic radiation. Monte-Carlo method is employed for estimating Eddington tensor with limited number of photon samples in each fluid time step. Radiation field from ablation plasma is significantly affected by the anisotropic Eddington tensor. Electron temperature around the ablation surface changes with the radiation field and is responsible for the observed emission. An accurate prediction of the light emission from the laser ablation plasma requires a careful estimation of the anisotropic radiation field.

  13. Effects of Laser Energy Density on Silicon Nanoparticles Produced Using Laser Ablation in Liquid

    Science.gov (United States)

    Kobayashi, Hiroki; Chewchinda, Pattarin; Ohtani, Hiroyuki; Odawara, Osamu; Wada, Hiroyuki

    2013-06-01

    We investigated the morphology of silicon nanoparticles prepared using laser ablation in liquid through varying the energy density and laser irradiation time. Silicon nanoparticles were prepared using laser ablation in liquid. A silicon wafer was irradiated in ethanol using a laser beam (Nd: YAG/second harmonic generation, 532 nm). Crystalline silicon nanoparticles approximately 6 nm in size were observed by TEM observation. The quantity of silicon nanoparticles proportionally increased with an increase in energy density greater than the laser ablation threshold. This quantity also increased with an increase in laser irradiation time without saturation due to absorption of the nanoparticles in liquid in the light path.

  14. Pulse laser ablation at water-air interface

    Science.gov (United States)

    Utsunomiya, Yuji; Kajiwara, Takashi; Nishiyama, Takashi; Nagayama, Kunihito; Kubota, Shiro

    2010-06-01

    We studied a new pulse laser ablation phenomenon on a liquid surface layer, which is caused by the difference between the refractive indices of the two materials involved. The present study was motivated by our previous study, which showed that laser ablation can occur at the interface between a transparent material and a gas or liquid medium when the laser pulse is focused through the transparent material. In this case, the ablation threshold fluence is reduced remarkably. In the present study, experiments were conducted in water and air in order to confirm this phenomenon for a combination of two fluid media with different refractive indices. This phenomenon was observed in detail by pulse laser shadowgraphy. A high-resolution film was used to record the phenomenon with a Nd:YAG pulse laser with 10-ns duration as a light source. The laser ablation phenomenon on the liquid surface layer caused by a focused Nd:YAG laser pulse with 1064-nm wavelength was found to be followed by the splashing of the liquid surface, inducing a liquid jet with many ligaments. The liquid jet extension velocity was around 1000 m/s in a typical case. The liquid jet decelerated drastically due to rapid atomization at the tips of the ligaments. The liquid jet phenomenon was found to depend on the pulse laser parameters such as the laser fluence on the liquid surface, laser energy, and laser beam pattern. The threshold laser fluence for the generation of a liquid jet was 20 J/cm2. By increasing the incident laser energy with a fixed laser fluence, the laser focused area increased, which eventually led to an increase in the size of the plasma column. The larger the laser energy, the larger the jet size and the longer the temporal behavior. The laser beam pattern was found to have significant effects on the liquid jet’s velocity, shape, and history.

  15. Ultrafast laser ablation for targeted atherosclerotic plaque removal

    Science.gov (United States)

    Lanvin, Thomas; Conkey, Donald B.; Descloux, Laurent; Frobert, Aurelien; Valentin, Jeremy; Goy, Jean-Jacques; Cook, Stéphane; Giraud, Marie-Noelle; Psaltis, Demetri

    2015-07-01

    Coronary artery disease, the main cause of heart disease, develops as immune cells and lipids accumulate into plaques within the coronary arterial wall. As a plaque grows, the tissue layer (fibrous cap) separating it from the blood flow becomes thinner and increasingly susceptible to rupturing and causing a potentially lethal thrombosis. The stabilization and/or treatment of atherosclerotic plaque is required to prevent rupturing and remains an unsolved medical problem. Here we show for the first time targeted, subsurface ablation of atherosclerotic plaque using ultrafast laser pulses. Excised atherosclerotic mouse aortas were ablated with ultrafast near-infrared (NIR) laser pulses. The physical damage was characterized with histological sections of the ablated atherosclerotic arteries from six different mice. The ultrafast ablation system was integrated with optical coherence tomography (OCT) imaging for plaque-specific targeting and monitoring of the resulting ablation volume. We find that ultrafast ablation of plaque just below the surface is possible without causing damage to the fibrous cap, which indicates the potential use of ultrafast ablation for subsurface atherosclerotic plaque removal. We further demonstrate ex vivo subsurface ablation of a plaque volume through a catheter device with the high-energy ultrafast pulse delivered via hollow-core photonic crystal fiber.

  16. Femtosecond laser ablation of polytetrafluoroethylene (Teflon) in ambient air

    International Nuclear Information System (INIS)

    Wang, Z.B.; Hong, M.H.; Lu, Y.F.; Wu, D.J.; Lan, B.; Chong, T.C.

    2003-01-01

    Teflon, polytetrafluorethylene (PTFE), is an important material in bioscience and medical application due to its special characteristics (bio-compatible, nonflammable, antiadhesive, and heat resistant). The advantages of ultrashort laser processing of Teflon include a minimal thermal penetration region and low processing temperatures, precision removal of material, and good-quality feature definition. In this paper, laser processing of PTFE in ambient air by a Ti:sapphire femtosecond laser (780 nm, 110 fs) is investigated. It is found that the pulse number on each irradiated surface area must be large enough for a clear edge definition and the ablated depth increases with the pulse number. The air ionization effect at high laser fluences not only degrades the ablated structures quality but also reduces the ablation efficiency. High quality microstructures are demonstrated with controlling laser fluence below a critical fluence to exclude the air ionization effect. The ablated microstructures show strong adhesion property to liquids and clear edges that are suitable for bio-implantation applications. Theoretical calculation is used to analyze the evolution of the ablated width and depth at various laser fluences

  17. Angular distributions and total yield of laser ablated silver

    DEFF Research Database (Denmark)

    Svendsen, Winnie Edith; Nordskov, A.; Schou, Jørgen

    1997-01-01

    The angular distribution of laser ablated silver has been measured in situ with a newly constructed setup with an array of microbalances. The distribution is strongly peaked in the forward direction corresponding to cospθ, where p varies between 5 and 9 for laser fluences from 2 to 7 J/cm2 at 355...

  18. UV solid state laser ablation of intraocular lenses

    Science.gov (United States)

    Apostolopoulos, A.; Lagiou, D. P.; Evangelatos, Ch.; Spyratou, E.; Bacharis, C.; Makropoulou, M.; Serafetinides, A. A.

    2013-06-01

    Commercially available intraocular lenses (IOLs) are manufactured from silicone and acrylic, both rigid (e.g. PMMA) and foldable (hydrophobic or hydrophilic acrylic biomaterials), behaving different mechanical and optical properties. Recently, the use of apodizing technology to design new diffractive-refractive multifocals improved the refractive outcome of these intraocular lenses, providing good distant and near vision. There is also a major ongoing effort to refine laser refractive surgery to correct other defects besides conventional refractive errors. Using phakic IOLs to treat high myopia potentially provides better predictability and optical quality than corneal-based refractive surgery. The aim of this work was to investigate the effect of laser ablation on IOL surface shaping, by drilling circular arrays of holes, with a homemade motorized rotation stage, and scattered holes on the polymer surface. In material science, the most popular lasers used for polymer machining are the UV lasers, and, therefore, we tried in this work the 3rd and the 5th harmonic of a Q-switched Nd:YAG laser (λ=355 nm and λ=213 nm respectively). The morphology of the ablated IOL surface was examined with a scanning electron microscope (SEM, Fei - Innova Nanoscope) at various laser parameters. Quantitative measurements were performed with a contact profilometer (Dektak-150), in which a mechanical stylus scanned across the surface of gold-coated IOLs (after SEM imaging) to measure variations in surface height and, finally, the ablation rates were also mathematically simulated for depicting the possible laser ablation mechanism(s). The experimental results and the theoretical modelling of UV laser interaction with polymeric IOLs are discussed in relation with the physical (optical, mechanical and thermal) properties of the material, in addition to laser radiation parameters (laser energy fluence, number of pulses). The qualitative aspects of laser ablation at λ=213 nm reveal a

  19. Assisted laser ablation: silver/gold nanostructures coated with silica

    Science.gov (United States)

    González-Castillo, J. R.; Rodríguez-González, Eugenio; Jiménez-Villar, Ernesto; Cesar, Carlos Lenz; Andrade-Arvizu, Jacob Antonio

    2017-11-01

    The synthesis processes of metallic nanoparticles have seen a growing interest in recent years, mainly by the potential applications of the phenomenon of localized surface plasmon resonance associated with metallic nanoparticles. This paper shows a fast method to synthesize silver, gold and silver/gold alloy nanoparticles coated with a porous silica shell by the assisted laser ablation method in three steps. The method involves a redox chemical reaction where the reducing agent is supplied in nanometric form by laser ablation. In the first step, a silicon target immersed in water is ablated for several minutes. Later, AgNO3 and HAuCl4 aliquots are added to the solution. The redox reaction between the silver and gold ions and products resulting from ablation process can produce silver, gold or silver/gold alloy nanoparticles coated with a porous silica shell. The influence of the laser pulse energy, ablation time, Ag+ and Au3+ concentration, as well as the Ag+/Au3+ ratio, on optical and structural properties of the nanostructures was investigated. This work represents a step forward in the study of reaction mechanisms that take place during the synthesis of nanoscale materials by the assisted laser ablation technique.

  20. Influence of liquid environments on femtosecond laser ablation of silicon

    International Nuclear Information System (INIS)

    Liu Hewei; Chen Feng; Wang Xianhua; Yang Qing; Bian Hao; Si Jinhai; Hou Xun

    2010-01-01

    Liquid-assisted ablation of solids by femtosecond laser pulses has proved to be an efficient tool for highly precise microfabrication, which evokes numerous research interests in recent years. In this paper, we systematically investigate the interaction of femtosecond laser pulses with silicon wafer in water, alcohol, and as a comparison, in air. After producing a series of multiple-shot craters on a silicon wafer in the three types of environments, surface morphologies and femtosecond laser-induced periodic surface structures are comparatively studied via the scanning electron microscope investigations. Meanwhile, the influence of liquid mediums on ablation threshold fluence and ablation depth is also numerically analyzed. The experimental results indicate that the ablation threshold fluences of silicon are reduced by the presence of liquids (water/alcohol) and ablation depths of craters are deepened in ambient water. Furthermore, smoother surfaces tend to be obtained in alcohol-mediated ablation at smaller shot numbers. Finally, the evolution of the femtosecond laser-induced periodic surface structures in air, water and alcohol is also discussed.

  1. Ablation behaviors of carbon reinforced polymer composites by laser of different operation modes

    Science.gov (United States)

    Wu, Chen-Wu; Wu, Xian-Qian; Huang, Chen-Guang

    2015-10-01

    Laser ablation mechanism of Carbon Fiber Reinforced Polymer (CFRP) composite is of critical meaning for the laser machining process. The ablation behaviors are investigated on the CFRP laminates subject to continuous wave, long duration pulsed wave and short duration pulsed wave lasers. Distinctive ablation phenomena have been observed and the effects of laser operation modes are discussed. The typical temperature patterns resulted from laser irradiation are computed by finite element analysis and thereby the different ablation mechanisms are interpreted.

  2. Laser ablation dynamics and production of thin films of lysozyme

    DEFF Research Database (Denmark)

    Canulescu, Stela; Schou, Jørgen; Amoruso, S.

    Lysozyme is a well-known protein, which is used in food processing because of its bactericidal properties. The mass (14307 amu) is in the range in which it easily can be monitored by mass spectrometric methods, for example by MALDI (Matrix assisted laser desorption ionization). We have recently....... This is the first time the ablation by fs-lasers of a protein has been recorded quantitatively. Films of lysozyme produced by fs-laser irradiation were analyzed by MALDI and a significant number of intact molecules in the films with fs-laser deposition was found as well....... impact. Samples of pressed lysozyme prepared in the same manner as in ns-experiments have been irradiated at 527 nm with 300-fs pulses and at at similar fluence as in ns ablation. Even though the pulse energy was much smaller, there was a considerable ablation weight loss of lysozyme from each shot...

  3. Laser ablation/ionization studies in a glow discharge

    International Nuclear Information System (INIS)

    Hess, K.R.; Harrison, W.W.

    1985-01-01

    The pin cathode glow discharge is used in the laboratory as an atomization/ionization source for a variety of applications, including solids mass spectrometry. Coupled with a tunable dye laser, the glow discharge may also serve as an atom reservoir for resonance ionization mass spectrometry in which the laser ionizes the discharge sputtered atoms. By tightly focusing the laser onto solid samples, various ablation effects may also be investigated. The laser may be used to generate an ionized plasma which may be directly analyzed by mass spectrometry. Alternatively, the ablated neutral atoms may be used in post-ablation excitation/ionization processes, in this case the glow discharge. The results of these investigations are the basis of this paper

  4. Pulsed Laser Ablation and Deposition with the Thomas Jefferson National Accelerator Facility Free Electron Laser

    Science.gov (United States)

    Reilly, Anne; Allmond, Chris; Shinn, Michelle

    2002-05-01

    We have been conducting some of the first experiments in pulsed laser ablation and deposition with the Thomas Jefferson National Accelerator Facility Free Electron Laser (TJNAF-FEL). The wavelength tunability, high average power (up to 1.72 kW), very high repetition rate (cw rate up to 74 MHz) and ultrafast pulses ( 650 fs) of the TJNAF-FEL present a combination of parameters unmatched by any laser, which has marked benefits for ablation and deposition. We will be presenting results on ablation of metals (Co,NiFe,Ti,Nb). Comparison with thin films deposited with a standard nanosecond laser source and an ultrafast low-repetition rate laser system show the advantage of using the FEL to produce high quality films at high deposition rates. Preliminary optical spectroscopy studies of the ablation plume and electron/ion emission studies during ablation will also be presented.

  5. Photoactive dye-enhanced tissue ablation for endoscopic laser prostatectomy.

    Science.gov (United States)

    Ahn, Minwoo; Hau, Nguyen Trung; Van Phuc, Nguyen; Oh, Junghwan; Kang, Hyun Wook

    2014-11-01

    Laser light has been widely used as a surgical tool to treat benign prostate hyperplasia (BPH) over 20 years. Recently, application of high laser power up to 200 W was often reported to swiftly remove a large amount of prostatic tissue. The purpose of this study was to validate the feasibility of photoactive dye injection to enhance light absorption and eventually to facilitate tissue vaporization with low laser power. Chicken breast tissue was selected as a target tissue due to minimal optical absorption at the visible wavelength. Four biocompatible photoactive dyes, including amaranth (AR), black dye (BD), hemoglobin powder (HP), and endoscopic marker (EM), were selected and tested in vitro with a customized 532 nm laser system with radiant exposure ranging from 0.9 to 3.9 J/cm(2) . Light absorbance and ablation threshold were measured with UV-Vis spectrometer and Probit analysis, respectively, and compared to feature the function of the injected dyes. Ablation performance with dye-injection was evaluated in light of radiant exposure, dye concentration, and number of injection. Higher light absorption by injected dyes led to lower ablation threshold as well as more efficient tissue removal in the order of AR, BD, HP, and EM. Regardless of the injected dyes, ablation efficiency principally increased with radiant exposure, dye concentration, and number of injection. Among the dyes, AR created the highest ablation rate of 44.2 ± 0.2 µm/pulse due to higher absorbance and lower ablation threshold. High aspect ratios up to 7.1 ± 0.4 entailed saturation behavior in the tissue ablation injected with AR and BD, possibly resulting from plume shielding and increased scattering due to coagulation. Preliminary tests on canine prostate with a hydraulic injection system demonstrated that 80 W with dye injection yielded comparable ablation efficiency to 120 W with no injection, indicating 33% reduced laser power with almost equivalent performance. Due to

  6. Ablation from metals induced by visible and UV laser irradiation

    DEFF Research Database (Denmark)

    Svendsen, Winnie Edith; Schou, Jørgen; Thestrup Nielsen, Birgitte

    1996-01-01

    The deposition rate of laser-ablated silver has been determined for fluences between 0.5 and 15 J/cm2 at the wavelengths 532 and 355 nm for a beam spot area of around 0.01 cm2. The ablated metal was collected on a quartz crystal microbalance. The rate at 5 J/cm2 was about 4 × 1013 Ag/cm2 per puls...

  7. Two-Dimensional Fluorescence Spectroscopy for Measuring Uranium Isotopes in Femtosecond Laser Ablation

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Mark C.; Brumfield, Brian E.; Harilal, Sivanandan S.; Hartig, Kyle C.; Jovanovic, Igor

    2017-05-30

    We present the first two-dimensional fluorescence spectroscopy measurements of uranium isotopes in femtosecond laser ablation plasmas. A new method of signal normalization is presented to reduce noise in absorption-based measurements of laser ablation.

  8. Infrared Laser Ablation with Vacuum Capture for Fingermark Sampling

    Science.gov (United States)

    Donnarumma, Fabrizio; Camp, Eden E.; Cao, Fan; Murray, Kermit K.

    2017-09-01

    Infrared laser ablation coupled to vacuum capture was employed to collect material from fingermarks deposited on surfaces of different porosity and roughness. Laser ablation at 3 μm was performed in reflection mode with subsequent capture of the ejecta with a filter connected to vacuum. Ablation and capture of standards from fingermarks was demonstrated on glass, plastic, aluminum, and cardboard surfaces. Using matrix assisted laser desorption ionization (MALDI), it was possible to detect caffeine after spiking with amounts as low as 1 ng. MALDI detection of condom lubricants and detection of antibacterial peptides from an antiseptic cream was demonstrated. Detection of explosives from fingermarks left on plastic surfaces as well as from direct deposition on the same surface using gas chromatography mass spectrometry (GC-MS) was shown. [Figure not available: see fulltext.

  9. Aggregation effect on absorbance spectrum of laser ablated gold nanoparticles

    Science.gov (United States)

    Isnaeni; Irmaniar; Herbani, Y.

    2017-04-01

    Plasmon of gold nanoparticles is one of the hot topics nowadays due to various possible applications. The application is determined by plasmon peak in absorbance spectrum. We have fabricated gold nanoparticles using laser ablation technique and studied the influence of CTAB (Cetyl trimethylammonium bromide) effect on the optical characterization of fabricated gold nanoparticles. We ablated a gold plate using NdYAG pulsed laser at 1064 nm wavelength, 10 Hz pulse frequency at low energy density. We found there are two distinctive plasmon peaks, i.e., primary and secondary peaks, where the secondary peak is the main interests of this work. Our simulation results have revealed that the secondary plasmon peak is affected by random aggregation of gold nanoparticles. Our research leads to good techniques on fabrication of colloidal gold nanoparticles in aqueous solution using laser ablation technique.

  10. Anterior two-thirds corpus callosotomy via stereotactic laser ablation.

    Science.gov (United States)

    Karsy, Michael; Patel, Daxa M; Halvorson, Kyle; Mortimer, Vance; Bollo, Robert J

    2018-04-01

    Anterior two-thirds corpus callosotomy is a common palliative surgical intervention most commonly employed in patients with atonic or drop seizures. Recently, stereotactic laser ablation of the corpus callosum without a craniotomy has shown promise in achieving similar outcomes with fewer side effects and shorter hospitalizations. The authors demonstrate ablation of the anterior two-thirds corpus callosum in a patient with Lennox-Gastaut syndrome and drug-resistant drop seizures. Technical nuances of laser ablation with 3 laser fibers are described. Postoperatively, the patient showed a significant reduction in seizure frequency and severity over a 9-month follow-up period. The video can be found here: https://youtu.be/3-mMq5-PLiM .

  11. Glass particles produced by laser ablation for ICP-MSmeasurements

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, J.; Liu, C.; Wen, S.; Mao, X.; Russo, R.E.

    2007-06-01

    Pulsed laser ablation (266nm) was used to generate glass particles from two sets of standard reference materials using femtosecond (150fs) and nanosecond (4ns) laser pulses with identical fluences of 50 J cm{sup -2}. Scanning electron microscopy (SEM) images of the collected particles revealed that there are more and larger agglomerations of particles produced by nanosecond laser ablation. In contrast to the earlier findings for metal alloy samples, no correlation between the concentration of major elements and the median particle size was found. When the current data on glass were compared with the metal alloy data, there were clear differences in terms of particle size, crater depth, heat affected zone, and ICP-MS response. For example, glass particles were larger than metal alloy particles, the craters in glass were less deep than craters in metal alloys, and damage to the sample was less pronounced in glass compared to metal alloys samples. The femtosecond laser generated more intense ICP-MS signals compared to nanosecond laser ablation for both types of samples, although glass sample behavior was more similar between ns and fs-laser ablation than for metals alloys.

  12. Fundamental Mechanisms of Pulsed Laser Ablation of Biological Tissue

    Science.gov (United States)

    Albagli, Douglas

    The ability to cut and remove biological tissue with short pulsed laser light, a process called laser ablation, has the potential to revolutionize many surgical procedures. Ablation procedures using short pulsed lasers are currently being developed or used in many fields of medicine, including cardiology, ophthalmology, dermatology, dentistry, orthopedics, and urology. Despite this, the underlying physics of the ablation process is not well understood. In fact, there is wide disagreement over whether the fundamental mechanism is primarily photothermal, photomechanical, or photochemical. In this thesis, both experimental and theoretical techniques are developed to explore this issue. The photothermal model postulates that ablation proceeds through vaporization of the target material. The photomechanical model asserts that ablation is initiated when the laser-induced tensile stress exceeds the ultimate tensile strength of the target. I have developed a three dimensional model of the thermoelastic response of tissue to short pulsed laser irradiation which allows the time dependent stress distribution to be calculated given the optical, thermal and mechanical properties of the target. A complimentary experimental technique has been developed to verify this model, measure the needed physical properties of the tissue, and record the thermoelastic response of the tissue at the onset of ablation. The results of this work have been widely disseminated to the international research community and have led to significant findings which support the photomechanical model of ablation of tissue. First, the energy deposited in tissue is an order of magnitude less than that required for vaporization. Second, unlike the one-dimensional thermoelastic model of laser-induced stress generation that has appeared in the literature, the full three-dimensional model predicts the development of significant tensile stresses on the surface of the target, precisely where ablation is observed to

  13. Laser propulsion to earth orbit. Has its time come?

    Science.gov (United States)

    Kantrowitz, Arthur

    1989-01-01

    Recent developments in high energy lasers, adaptive optics, and atmospheric transmission bring laser propulsion much closer to realization. Proposed here is a reference vehicle for study which consists of payload and solid propellant (e.g. ice). A suitable laser pulse is proposed for using a Laser Supported Detonation wave to produce thrust efficiently. It seems likely that a minimum system (10 Mw CO2 laser and 10 m dia. mirror) could be constructed for about $150 M. This minimum system could launch payloads of about 13 kg to a 400 km orbit every 10 minutes. The annual launch capability would be about 683 tons times the duty factor. Laser propulsion would be an order of magnitude cheaper than chemical rockets if the duty factor was 20 percent (10,000 launches/yr). Launches beyond that would be even cheaper. The chief problem which needs to be addressed before these possibilities could be realized is the design of a propellant to turn laser energy into thrust efficiently and to withstand the launch environment.

  14. Pulsed CO2 laser tissue ablation: measurement of the ablation rate.

    Science.gov (United States)

    Walsh, J T; Deutsch, T F

    1988-01-01

    Ablation of guinea pig skin using a CO2 laser emitting 2-mu sec-long pulses has been quantified by measuring the mass of tissue removed as a function of incident fluence per pulse. The mass-loss curves show three distinct regimes in which water evaporation, explosive tissue removal, and laser-induced plasma formation dominate. The data are fit to two models that predict that the mass removed depends either linearly or logarithmically on fluence. Although the data are best fit by a linear dependence upon fluence, plasma formation at high fluences prohibited obtaining data over a wide enough fluence range to differentiate unambiguously between the two models. Ablation efficiency, ablation thresholds, and the optical penetration depth at 10.6 micron were obtained from the measurements.

  15. Observation of the initial stage of the laser ablation

    International Nuclear Information System (INIS)

    Miyashita, Atsumi; Yoda, Osamu; Ohyanagi, Takasumi; Murakami, Kouichi.

    1994-01-01

    The time and space resolved properties of laser ablated carbon particles were measured by X-ray absorption spectroscopy using Laser Plasma X-ray (LPX) as an X-ray source. The energy density of the irradiation laser on the sample was in the range of 0.5-20 J/cm 2 and the time delay was varied between 0 and 120ns. The absorption spectra exhibits several peaks originated from level to level transitions and an intense broad absorption in the energy range of C-K edge. At a delay time of 120ns, the absorption peak of 1s → 2p transition of neutral carbon atom (C 0 ), C - , C + and C 2+ ions were observed. The absorption peak from C 0 is stronger as the probing position is closer to the sample surface and its intensity decreases rapidly with distance from the sample surface. The absorption peak C 2+ ion was observed only at comparatively distant positions from surface. The maximum speed of highly charged ions are faster than that of neutral atoms and negative charged ions. The neutral atom and lower charged ions are emitted from the sample surface even after laser irradiation. The spatial distribution of the laser ablated particles in the localized helium gas environment were measured. In the helium gas environment, the ablation plume is depressed by the helium cloud generated on the top of ablation plume. (author)

  16. Formation and characterization of nanoparticles via laser ablation in solution

    Science.gov (United States)

    Golightly, Justin Samuel

    The work presented in this thesis encompassed laser ablation of various transition metals within a liquid environment. Through an improved understanding of the ablation process, control over the properties of the resultant nanoparticles can be obtained, and thusly nanoparticles can be tailored with specific properties. Creation of nanoparticles via laser ablation in solution is a relatively youngtechnique for nanoparticle synthesis, and the work presented should prove useful in guiding further exploration in ablation processes in liquids for nanomaterial production. When a laser is focused onto a target under a liquid environment, the target material and its surrounding liquid are vaporized. The concoction of vapor is ejected normal to the surface as a bubble. The bubble has a temperature reaching the boiling point of the metal, and has a gradient to the boiling point of the solvent. The bubble expands until it reaches a critical volume, and then subsequently collapses. It is within this bubble that nanoparticle formation occurs. As the bubble expands, the vapor cools and nanoparticle growth transpires. During the bubble collapse, pressures reaching GigaPascals have been reported, and a secondary nanoparticle formation occurs as a result of these high pressures. Chapter 1 delves a little more into the nanoparticle formation mechanisms, as well as an introduction to the analytical techniques used for characterization. Ablation of titanium took place in isopropanol, ethanol, water, and n-hexane, under various fluences, with a 532 nm Nd:YAG operating at 10 Hz. It was found that a myriad of nanoparticles could be made with vastly different compositions that were both solvent and fluence dependent. Nanoparticles were made that incorporated carbon and oxygen from the solvent, showing how solvent choice is an important factor in nanoparticle creation. Chapter 3 discusses the results of the titanium work in great detail and demonstrates carbide production with ablation in

  17. High resolution selective multilayer laser processing by nanosecond laser ablation of metal nanoparticle films

    International Nuclear Information System (INIS)

    Ko, Seung H.; Pan Heng; Hwang, David J.; Chung, Jaewon; Ryu, Sangil; Grigoropoulos, Costas P.; Poulikakos, Dimos

    2007-01-01

    Ablation of gold nanoparticle films on polymer was explored using a nanosecond pulsed laser, with the goal to achieve feature size reduction and functionality not amenable with inkjet printing. The ablation threshold fluence for the unsintered nanoparticle deposit was at least ten times lower than the reported threshold for the bulk film. This could be explained by the combined effects of melting temperature depression, lower conductive heat transfer loss, strong absorption of the incident laser beam, and the relatively weak bonding between nanoparticles. The ablation physics were verified by the nanoparticle sintering characterization, ablation threshold measurement, time resolved ablation plume shadowgraphs, analysis of ablation ejecta, and the measurement and calculation of optical properties. High resolution and clean feature fabrication with small energy and selective multilayer processing are demonstrated

  18. Emission spectroscopy analysis during Nopal cladodes dethorning by laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Pena-Diaz, M; Ponce, L; Arronte, M; Flores, T [Laboratorio TecnologIa Laser, CICATA-IPN, Unidad Altamira, Carretera Tampico-Puerto Ind. Altamira, 89600, TAMPS (Mexico)

    2007-04-15

    Optical emission spectroscopy of the pulsed laser ablation of spines and glochids from Opuntia (Nopal) cladodes was performed. Nopal cladodes were irradiated with Nd:YAG free-running laser pulses on their body, glochids and spines. Emission spectroscopy analyses in the 350-1000 nm region of the laser induced plasma were made. Plasma plume evolution characterization, theoretical calculations of plasma plume temperature and experiments varying the processing atmosphere showed that the process is dominated by a thermally activated combustion reaction which increases the dethorning process efficiency. Therefore, appropriate laser pulse energy for minimal damage of cladodes body and in the area beneath glochids and spines can be obtained.

  19. Emission spectroscopy analysis during Nopal cladodes dethorning by laser ablation

    Science.gov (United States)

    Peña-Díaz, M.; Ponce, L.; Arronte, M.; Flores, T.

    2007-04-01

    Optical emission spectroscopy of the pulsed laser ablation of spines and glochids from Opuntia (Nopal) cladodes was performed. Nopal cladodes were irradiated with Nd:YAG free-running laser pulses on their body, glochids and spines. Emission spectroscopy analyses in the 350-1000 nm region of the laser induced plasma were made. Plasma plume evolution characterization, theoretical calculations of plasma plume temperature and experiments varying the processing atmosphere showed that the process is dominated by a thermally activated combustion reaction which increases the dethorning process efficiency. Therefore, appropriate laser pulse energy for minimal damage of cladodes body and in the area beneath glochids and spines can be obtained.

  20. Laser ablation dynamics and production of thin films of lysozyme

    DEFF Research Database (Denmark)

    Schou, Jørgen; Canulescu, Stela; Matei, Andreea

    Lysozyme is a well-known protein, which is used in food processing because of its bacteriocidal properties. The mass (14307 u) is in the range, in which it easily can be controlled by mass spectrometric methods, for example by MALDI (Matrix assisted laser desorption ionisation). We have recently......, there was a considerable ablation weight loss of lysozyme from each shot. This is the first time the ablation by fs-lasers of a protein has been recorded quantitatively. Films of lysozyme produced by fs-laser irradiation will be analysed by MALDI in order to explore if there also is a significant amount of intact...... these experiments at CNR-SPIN, Napoli, to explore the excitation mechanics by laser impact. Samples of pressed lysozyme prepared in the same manner as in DTU have been irradiated at 523 nm with 300-fs pulses and a fluence of the same order of magnitude as in DYU. Even though the pulse energy was much smaller...

  1. Erosion of nanostructured tungsten by laser ablation, sputtering and arcing

    Directory of Open Access Journals (Sweden)

    Dogyun Hwangbo

    2017-08-01

    Full Text Available Mass loss of nanostructured tungsten, which was formed by helium plasma irradiation, due to laser ablation, sputtering, and arcing was investigated. Below the helium sputtering energy threshold (200eV. Reduction in sputtering on nanostructured surface was observed. Arcing was initiated using laser pulses, and the erosion rate by arcing was measured. The erosion rate increased with arc current, while the erosion per Coulomb was not affected by arc current.

  2. Langmuir probe study of plasma expansion in pulsed laser ablation

    DEFF Research Database (Denmark)

    Hansen, T.N.; Schou, Jørgen; Lunney, J.G.

    1999-01-01

    Langmuir probes were used to monitor the asymptotic expansion of the plasma produced by the laser ablation of a silver target in a vacuum. The measured angular and temporal distributions of the ion flux and electron temperature were found to be in good agreement with the self-similar isentropic...

  3. Absorption Enhanced Liquid Ablation with TEA CO2 Laser

    National Research Council Canada - National Science Library

    Sterling, Enrique

    2004-01-01

    ... that strongly absorbs radiation in the 8-11 m wavelength interval. A TEA CO2 laser (λ = 10.6 m), 300 ns pulse width and 8 J pulse energy, was used for ablation of water diluted NaBF4 contained in a conical aluminum nozzle...

  4. Online Monitoring of Nanoparticles Formed during Nanosecond Laser Ablation.

    Czech Academy of Sciences Publication Activity Database

    Nováková, H.; Holá, M.; Vojtíšek-Lomb, M.; Ondráček, Jakub; Kanický, V.

    2016-01-01

    Roč. 125, NOV 1 (2016), s. 52-60 ISSN 0584-8547 R&D Projects: GA ČR(CZ) GBP503/12/G147 Institutional support: RVO:67985858 Keywords : laser ablation * fast mobility particle sizer * inductively coupled plasma mass spectrometry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.241, year: 2016

  5. Zinc nanoparticles in solution by laser ablation technique

    Indian Academy of Sciences (India)

    TECS

    Physical and chemical properties of these materi- als are highly size dependent. Therefore, it is important ... provided a powerful tool for the synthesis of nanomaterials in both solutions and gas matrices (Hodak et al ... 2006) and magnetic characterization of Co–Pt nanoparti- cles are reported by laser ablation of Co–Pt bulk ...

  6. Superhydrophobic/superoleophilic magnetic elastomers by laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Milionis, Athanasios, E-mail: am2vy@virginia.edu [Smart Materials-Nanophysics, Istituto Italiano di Tecnologia (IIT), Via Morego 30, 16163 Genova (Italy); Fragouli, Despina; Brandi, Fernando; Liakos, Ioannis; Barroso, Suset [Smart Materials-Nanophysics, Istituto Italiano di Tecnologia (IIT), Via Morego 30, 16163 Genova (Italy); Ruffilli, Roberta [Nanochemistry, Istituto Italiano di Tecnologia (IIT), Via Morego 30, 16163 Genova (Italy); Athanassiou, Athanassia, E-mail: athanassia.athanassiou@iit.it [Smart Materials-Nanophysics, Istituto Italiano di Tecnologia (IIT), Via Morego 30, 16163 Genova (Italy)

    2015-10-01

    Highlights: • We report the development of magnetic nanocomposite sheets. • Laser irradiation of the nanocomposites induces chemical and structural changes to the surface. • The laser-patterned surfaces exhibit superhydrophobicity and superoleophilicity. • The particle contribution in altering the surface and bulk properties of the material is studied. - Abstract: We report the development of magnetic nanocomposite sheets with superhydrophobic and supeoleophilic surfaces generated by laser ablation. Polydimethylsiloxane elastomer free-standing films, loaded homogeneously with 2% wt. carbon coated iron nanoparticles, were ablated by UV (248 nm), nanosecond laser pulses. The laser irradiation induces chemical and structural changes (both in micro- and nano-scale) to the surfaces of the nanocomposites rendering them superhydrophobic. The use of nanoparticles increases the UV light absorption efficiency of the nanocomposite samples, and thus facilitates the ablation process, since the number of pulses and the laser fluence required are greatly reduced compared to the bare polymer. Additionally the magnetic nanoparticles enhance significantly the superhydrophobic and oleophilic properties of the PDMS sheets, and provide to PDMS magnetic properties making possible its actuation by a weak external magnetic field. These nanocomposite elastomers can be considered for applications requiring magnetic MEMS for the controlled separation of liquids.

  7. Pulsed laser deposition: metal versus oxide ablation

    NARCIS (Netherlands)

    Doeswijk, L.M.; Rijnders, Augustinus J.H.M.; Blank, David H.A.

    2004-01-01

    We present experimental results of pulsed laser interaction with metal (Ni, Fe, Nb) and oxide (TiO2, SrTiO3, BaTiO3) targets. The influence of the laser fluence and the number of laser pulses on the resulting target morphology are discussed. Although different responses for metal and oxide targets

  8. Study of Laser Ablation Efficiency for an Acrylic-Based Photopolymerizing Composition

    Science.gov (United States)

    Loktionov, E. Yu.

    2014-05-01

    Results are presented from study of the effi ciency (ablated mass per unit energy, mechanical recoil momentum per unit energy) of laser ablation for a light-curable polymer. A substantial difference is seen between the thresholds and indicated criteria for laser ablation effi ciency in the liquid and cured phases. The highest energy effi ciency for laser ablation (~22.6 %) is achieved when the initially liquid polymer is exposed to radiation with the wavelength optimal for photopolymerization (365 ± 15 nm).

  9. Percutaneous laser ablation of unresectable primary and metastatic adrenocortical carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Pacella, Claudio M. [Regina Apostolorum Hospital, Department of Diagnostic Imaging and Interventional Radiology, Via San Francesco 50, Albano Laziale, Rome 00041 (Italy)], E-mail: claudiomaurizio.pacella@fastwebnet.it; Stasi, Roberto; Bizzarri, Giancarlo; Pacella, Sara; Graziano, Filomena Maria; Guglielmi, Rinaldo; Papini, Enrico [Regina Apostolorum Hospital, Department of Diagnostic Imaging and Interventional Radiology, Via San Francesco 50, Albano Laziale, Rome 00041 (Italy)

    2008-04-15

    Purpose: To evaluate the feasibility, safety, and clinical benefits of percutaneous laser ablation (PLA) in patients with unresectable primary and metastatic adrenocortical carcinoma (ACC). Patients and methods: Four patients with hepatic metastases from ACC and a Cushing's syndrome underwent ultrasound-guided PLA. In one case the procedure was performed also on the primary tumor. Results: After three sessions of PLA, the primary tumor of 15 cm was ablated by 75%. After 1-4 (median 1) sessions of PLA, five liver metastases ranging from 2 to 5 cm were completely ablated, while the sixth tumor of 12 cm was ablated by 75%. There were no major complications. Treatment resulted in an improvement of performance status and a reduction of the daily dosage of mitotane in all patients. The three patients with liver metastases presented a marked decrease of 24-h urine cortisol levels, an improved control of hypertension and a mean weight loss of 2.8 kg. After a median follow-up after PLA of 27.0 months (range, 9-48 months), two patients have died of tumor progression, while two other patients remain alive and free of disease. Conclusions: Percutaneous laser ablation is a feasible, safe and well tolerated procedure for the palliative treatment of unresectable primary and metastatic ACC. Further study is required to evaluate the impact of PLA on survival.

  10. Numerical analysis of laser ablation and damage in glass with multiple picosecond laser pulses.

    Science.gov (United States)

    Sun, Mingying; Eppelt, Urs; Russ, Simone; Hartmann, Claudia; Siebert, Christof; Zhu, Jianqiang; Schulz, Wolfgang

    2013-04-08

    This study presents a novel numerical model for laser ablation and laser damage in glass including beam propagation and nonlinear absorption of multiple incident ultrashort laser pulses. The laser ablation and damage in the glass cutting process with a picosecond pulsed laser was studied. The numerical results were in good agreement with our experimental observations, thereby revealing the damage mechanism induced by laser ablation. Beam propagation effects such as interference, diffraction and refraction, play a major role in the evolution of the crater structure and the damage region. There are three different damage regions, a thin layer and two different kinds of spikes. Moreover, the electronic damage mechanism was verified and distinguished from heat modification using the experimental results with different pulse spatial overlaps.

  11. Thermal Ablation of Colorectal Lung Metastases: Retrospective Comparison Among Laser-Induced Thermotherapy, Radiofrequency Ablation, and Microwave Ablation.

    Science.gov (United States)

    Vogl, Thomas J; Eckert, Romina; Naguib, Nagy N N; Beeres, Martin; Gruber-Rouh, Tatjana; Nour-Eldin, Nour-Eldin A

    2016-12-01

    The purpose of this study is to retrospectively evaluate local tumor control, time to tumor progression, and survival rates among patients with lung metastatic colorectal cancer who have undergone ablation therapy performed using laser-induced thermotherapy (LITT), radiofrequency ablation (RFA), or microwave ablation (MWA). Data for this retrospective study were collected from 231 CT-guided ablation sessions performed for 109 patients (71 men and 38 women; mean [± SD] age, 68.6 ± 11.2 years; range, 34-94 years) from May 2000 to May 2014. Twenty-one patients underwent LITT (31 ablations), 41 patients underwent RFA (75 ablations), and 47 patients underwent MWA (125 ablations). CT scans were acquired 24 hours after each therapy session and at follow-up visits occurring at 3, 6, 12, 18, and 24 months after ablation. Survival rates were calculated from the time of the first ablation session, with the use of Kaplan-Meier and log-rank tests. Changes in the volume of the ablated lesions were measured using the Kruskal-Wallis method. Local tumor control was achieved in 17 of 25 lesions (68.0%) treated with LITT, 45 of 65 lesions (69.2%) treated with RFA, and 91 of 103 lesions (88.3%) treated with MWA. Statistically significant differences were noted when MWA was compared with LITT at 18 months after ablation (p = 0.01) and when MWA was compared with RFA at 6 months (p = 0.004) and 18 months (p = 0.01) after ablation. The overall median time to local tumor progression was 7.6 months. The median time to local tumor progression was 10.4 months for lesions treated with LITT, 7.2 months for lesions treated with RFA, and 7.5 months for lesions treated with MWA, with no statistically significant difference noted. New pulmonary metastases developed in 47.6% of patients treated with LITT, in 51.2% of patients treated with RFA, and in 53.2% of patients treated with MWA. According to the Kaplan-Meier test, median survival was 22.1 months for patients who underwent LITT, 24.2 months

  12. Frequency mixing in boron carbide laser ablation plasmas

    Science.gov (United States)

    Oujja, M.; Benítez-Cañete, A.; Sanz, M.; Lopez-Quintas, I.; Martín, M.; de Nalda, R.; Castillejo, M.

    2015-05-01

    Nonlinear frequency mixing induced by a bichromatic field (1064 nm + 532 nm obtained from a Q-switched Nd:YAG laser) in a boron carbide (B4C) plasma generated through laser ablation under vacuum is explored. A UV beam at the frequency of the fourth harmonic of the fundamental frequency (266 nm) was generated. The dependence of the efficiency of the process as function of the intensities of the driving lasers differs from the expected behavior for four-wave mixing, and point toward a six-wave mixing process. The frequency mixing process was strongly favored for parallel polarizations of the two driving beams. Through spatiotemporal mapping, the conditions for maximum efficiency were found for a significant delay from the ablation event (200 ns), when the medium is expected to be a low-ionized plasma. No late components of the harmonic signal were detected, indicating a largely atomized medium.

  13. Near-field mapping by laser ablation of PMMA coatings

    DEFF Research Database (Denmark)

    Fiutowski, J.; Maibohm, C.; Kostiucenko, O.

    2011-01-01

    enhancements on and around the gold nanostructures. At the positions of the enhancements, the ablation threshold of the polymer coating is significantly lowered creating subdiffractional topographic modifications on the surface which are quantified via scanning electron microscopy and atomic force microscopy......The optical near-field of lithography-defined gold nanostructures, arranged into regular arrays on a gold film, is characterized via ablation of a polymer coating by laser illumination. The method utilizes femto-second laser pulses from a laser scanning microscope which induces electrical field....... The obtained experimental results for different polymer coating thicknesses and nanostructure geometries are in good agreement with theoretical calculations of the near field distribution for corresponding enhancement mechanisms. The developed method and its tunable experimental parameters show...

  14. Angular distribution of laser ablation plasma

    International Nuclear Information System (INIS)

    Kondo, K.; Kanesue, T.; Dabrowski, R.; Okamura, M.

    2010-01-01

    An expansion of a laser induced plasma is fundamental and important phenomena in a laser ion source. To understand the expanding direction, an array of Langmuir probes were employed. The chosen ion for the experiment was Ag 1+ which was created by a second harmonics of a Nd-YAG laser. The obtained angular distribution was about ±10 degree. This result also indicates a proper positioning of a solenoid magnet which enhances ion beam current.

  15. Laser ablation of silver and gold in liquid ammonia

    Science.gov (United States)

    Šmejkal, Petr; Pfleger, Jiří; Vlčková, Blanka

    2010-10-01

    Laser ablation of a silver (Ag) and/or gold (Au) target was performed in liquid ammonia (l-NH3) at 233 K using nanosecond laser pulses of 1064, 532 and 355 nm wavelengths. An “in situ” monitoring of the ablation process by UV/vis/NIR spectroscopy has shown the evolution of the surface plasmon extinction band of silver or gold nanoparticles and thus confirmed their formation. While sols of Au nanoparticles in l-NH3 are quite stable in air, those of Ag nanoparticles undergo oxidation to Ag(I) complexes with NH3 ligands. On the other hand, formation of solvated electrons, namely of the (e-)NH3 solvates, has not been unequivocally confirmed under the conditions of our laser ablation/nanoparticle fragmentation experiment, since only very weak vis/NIR spectral features of these solvates were observed with a low reproducibility. Reference experiments have shown that the well-known chemical production of these solvates is hindered by the presence of Ag and Au plates. Ag and Au targets can thus possibly act as electron scavengers in our ablation experiments.

  16. Laser ablation of titanium in liquid in external electric field

    Energy Technology Data Exchange (ETDEWEB)

    Serkov, A.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); The Federal State Educational Institution of Higher Professional Education, “Moscow Institute of Physics and Technology (State University)”, 9 Institutskiy per., 141700, Dolgoprudny, Moscow Region (Russian Federation); Barmina, E.V., E-mail: barminaev@gmail.com [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); Shafeev, G.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 31, Kashirskoye Highway, 115409 Moscow (Russian Federation); Voronov, V.V. [A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation)

    2015-09-01

    Highlights: • Ablation of a bulk Ti target by 10 ps laser pulses in liquid is experimentally studied in external DC electric field. • Applied cathodic bias leads to increase in average size of self-organized nanostructures formed upon ablation of titanium target. • Laser ablation of Ti target in external electric field results in generation of elongated titanium oxide nanoparticles. - Abstract: Ablation of a bulk Ti target by 10 ps laser pulses in water is experimentally studied in external DC electric field. It is demonstrated that both lateral size of nanostructures (NS) on Ti surface and their density depend on the electric field applied to the target. Scanning Electron Microscopy of NS reveals the shift of their size distribution function toward larger sizes with applied field (cathodic bias, 25 V DC). Density of mushroom-like NS with applied electric field amounts to 10{sup 10} cm{sup −2}. X-ray diffraction of generated nanoparticles (NPs) shows difference in the crystallographic structure of NPs of non-stoichiometric Ti oxides generated with and without electric field. This conclusion is corroborated with the optical absorption spectroscopy of obtained colloids. Transmission Electron Microscopy of NPs also shows difference in morphology of particles produced with and without cathodic bias. The results are interpreted on the basis of instability of the melt on Ti surface in the electric field.

  17. Comparison of ablation stake measurements and Airborne Laser Scanning results

    Science.gov (United States)

    Rieg, Lorenzo; Galos, Stephan; Klug, Christoph; Sailer, Rudolf

    2014-05-01

    Ablation measurements using ablation stakes are a well-established method in glaciology, which sees a lot of use. However, ablation stakes cannot always be installed and read at a sufficient number of points on a glacier or on multiple glaciers, due to limited personnel and financial capacities or because of inaccessible areas due to dangerous zones (crevasses, rock falls, avalanches) or remote terrain. Furthermore, ablation stakes only enable measurements of surface melt, whereas basal or internal melt processes as well as surface change related to glacier dynamics cannot be measured. Multi temporal Airborne laser scanning (ALS) can provide high resolution and very accurate topographic information for the whole glacier area, which allows the calculation of the difference in surface height and therefore - if the density profile is known or can be estimated - the determination of the local mass balance, including processes like basal melt at least to a certain degree. To gain a better understanding of the differences between ablation stake readings and differential ALS data at the stake locations, the results of both methods have been compared in detail. At Langenferner, a glacier in the Italian Eastern Alps, where mass balance measurements have been carried out since 2004, three ALS campaigns have been conducted at the end of the hydrological year in 2005, 2010 and 2013. There are about 30 ablation stakes installed at the glacier, which have been read during or very close to the time of the flight campaigns. The ablation measurements are then compared to the surface differences calculated from ALS data at the locations of the ablation stakes. To take the movement of the stakes due to glacier dyanmics into account, the position of the stakes has been measured with a differential GPS.

  18. Laser-fusion rocket for interplanetary propulsion

    International Nuclear Information System (INIS)

    Hyde, R.A.

    1983-01-01

    A rocket powered by fusion microexplosions is well suited for quick interplanetary travel. Fusion pellets are sequentially injected into a magnetic thrust chamber. There, focused energy from a fusion Driver is used to implode and ignite them. Upon exploding, the plasma debris expands into the surrounding magnetic field and is redirected by it, producing thrust. This paper discusses the desired features and operation of the fusion pellet, its Driver, and magnetic thrust chamber. A rocket design is presented which uses slightly tritium-enriched deuterium as the fusion fuel, a high temperature KrF laser as the Driver, and a thrust chamber consisting of a single superconducting current loop protected from the pellet by a radiation shield. This rocket can be operated with a power-to-mass ratio of 110 W gm -1 , which permits missions ranging from occasional 9 day VIP service to Mars, to routine 1 year, 1500 ton, Plutonian cargo runs

  19. Microscopic and macroscopic modeling of femtosecond laser ablation of metals

    Energy Technology Data Exchange (ETDEWEB)

    Povarnitsyn, Mikhail E., E-mail: povar@ihed.ras.ru; Fokin, Vladimir B.; Levashov, Pavel R.

    2015-12-01

    Highlights: • We model laser ablation of aluminum using microscopic and macroscopic approaches. • We examine the domain of applicability for hydrodynamics and molecular dynamics. • Molecular dynamics describes ultra-fast processes of melting and fragmentation. • Hydrodynamics with a model of nucleation agrees well with molecular dynamics. • Both computational methods give similar ablation crater depths. - Abstract: Simulation of femtosecond laser ablation of a bulk aluminum target is performed using two complementary approaches. The first method is single-fluid two-temperature hydrodynamics (HD) completed with a two-temperature equation of state (EOS). The second approach is a combination of classical molecular dynamics (MD) and a continuum model of a free electron subsystem. In both methods, an identical and accurate description of optical and transport properties of the electron subsystem is based on wide-range models reproducing effects of electron heat wave propagation, electron–phonon/ion coupling and laser energy absorption on a time-dependent profile of the dielectric function. For simulation of homogeneous nucleation in a metastable liquid phase, a kinetic model of nucleation is implemented in the HD approach. The phase diagrams of the EOS and MD potential are in good agreement that gives opportunity to compare the dynamics of laser ablation obtained by both methods directly. Results of simulation are presented in the range of incident fluences 0.1–20 J/cm{sup 2} and match well with experimental findings for an ablation crater depth. The MD accurately reproduces nonequilibrium phase transitions and takes into account surface effects on nanoscale. The HD approach demonstrates good qualitative agreement with the MD method in the dynamics of phase explosion and spallation. Other advantages and disadvantages of both approaches are examined and discussed.

  20. PREFACE AND CONFERENCE INFORMATION: Eighth International Conference on Laser Ablation

    Science.gov (United States)

    Hess, Wayne P.; Herman, Peter R.; Bäuerle, Dieter; Koinuma, Hideomi

    2007-04-01

    Laser ablation encompasses a wide range of delicate to extreme light interactions with matter that present considerably challenging problems for scientists to study and understand. At the same time, laser ablation also represents a basic process of significant commercial importance in laser material processing—defining a multi-billion dollar industry today. These topics were widely addressed at the 8th International Conference on Laser Ablation (COLA), held in Banff, Canada on 11-16 September 2005. The meeting took place amongst the majestic and natural beauty of the Canadian Rocky Mountains at The Banff Centre, where delegates enjoyed many inspiring presentations and discussions in a unique campus learning environment. The conference brought together world leading scientists, students and industry representatives to examine the basic science of laser ablation and improve our understanding of the many physical, chemical and/or biological processes driven by the laser. The multi-disciplinary research presented at the meeting underlies some of our most important trends at the forefront of science and technology today that are represented in the papers collected in this volume. Here you will find new processes that are producing novel types of nanostructures and nano-materials with unusual and promising properties. Laser processes are described for delicately manipulating living cells or modifying their internal structure with unprecedented degrees of control and precision. Learn about short-pulse lasers that are driving extreme physical processes on record-fast time scales and opening new directions from material processing applications. The conference papers further highlight forefront application areas in pulsed laser deposition, nanoscience, analytical methods, materials, and microprocessing applications. Laser ablation continues to grow and evolve, touching forefront areas in science and driving new technological trends in laser processing applications. Please

  1. Histological evaluation of vertical laser channels from ablative fractional resurfacing

    DEFF Research Database (Denmark)

    Skovbølling Haak, Christina; Illes, Monica; Paasch, Uwe

    2011-01-01

    Ablative fractional resurfacing (AFR) represents a new treatment potential for various skin conditions and new laser devices are being introduced. It is important to gain information about the impact of laser settings on the dimensions of the created laser channels for obtaining a safe...... and efficient treatment outcome. The aim of this study was to establish a standard model to document the histological tissue damage profiles after AFR and to test a new laser device at diverse settings. Ex vivo abdominal pig skin was treated with a MedArt 620, prototype fractional carbon dioxide (CO(2)) laser...... measurements for each laser setting (n = 28). AFR created cone-shaped laser channels. Ablation depths varied from reaching the superficial dermis (2 mJ, median 41 μm) to approaching the subcutaneous fat (144 mJ, median 1,943 μm) and correlated to the applied energy levels in an approximate linear relation (r(2...

  2. Ablation of silicon with bursts of femtosecond laser pulses

    Science.gov (United States)

    Gaudiuso, Caterina; Kämmer, Helena; Dreisow, Felix; Ancona, Antonio; Tünnermann, Andreas; Nolte, Stefan

    2016-03-01

    We report on an experimental investigation of ultrafast laser ablation of silicon with bursts of pulses. The pristine 1030nm-wavelength 200-fs pulses were split into bursts of up to 16 sub-pulses with time separation ranging from 0.5ps to 4080ps. The total ablation threshold fluence was measured depending on the burst features, finding that it strongly increases with the number of sub-pulses for longer sub-pulse delays, while a slowly increasing trend is observed for shorter separation time. The ablation depth per burst follows two different trends according to the time separation between the sub-pulses, as well as the total threshold fluence. For delays shorter than 4ps it decreases with the number of pulses, while for time separations longer than 510ps, deeper craters were achieved by increasing the number of subpulses in the burst, probably due to a change of the effective penetration depth.

  3. Interaction between a bubble and a metal target for underwater laser propulsion.

    Science.gov (United States)

    Qiang, Hao; Chen, Jun; Han, Bing; Pan, Yunxiang; Zhang, Hongchao; Shen, Zhonghua; Lu, Jian; Ni, Xiaowu

    2017-04-10

    Optical beam deflection and high-speed photographic methods are employed to investigate the interaction mechanism between a laser-induced bubble and a metal target for underwater laser propulsion. A preliminary theory is proposed to reveal the step increases of the kinetic energy transferred to the target during the process of increasing the incident laser energy. This theory also helps to explain the increasing coupling efficiency with incident laser energy for underwater laser propulsion.

  4. Frequency mixing in boron carbide laser ablation plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Oujja, M.; Benítez-Cañete, A.; Sanz, M.; Lopez-Quintas, I.; Martín, M.; Nalda, R. de, E-mail: r.nalda@iqfr.csic.es; Castillejo, M.

    2015-05-01

    Graphical abstract: - Highlights: • Two-color frequency mixing has been studied in a laser ablation boron carbide plasma. • A space- and time-resolved study mapped the nonlinear optical species in the plasma. • The nonlinear process maximizes when charge recombination is expected to be completed. • Neutral atoms and small molecules are the main nonlinear species in this medium. • Evidence points to six-wave mixing as the most likely process. - Abstract: Nonlinear frequency mixing induced by a bichromatic field (1064 nm + 532 nm obtained from a Q-switched Nd:YAG laser) in a boron carbide (B{sub 4}C) plasma generated through laser ablation under vacuum is explored. A UV beam at the frequency of the fourth harmonic of the fundamental frequency (266 nm) was generated. The dependence of the efficiency of the process as function of the intensities of the driving lasers differs from the expected behavior for four-wave mixing, and point toward a six-wave mixing process. The frequency mixing process was strongly favored for parallel polarizations of the two driving beams. Through spatiotemporal mapping, the conditions for maximum efficiency were found for a significant delay from the ablation event (200 ns), when the medium is expected to be a low-ionized plasma. No late components of the harmonic signal were detected, indicating a largely atomized medium.

  5. Plasma dynamics from laser ablated solid lithium

    Indian Academy of Sciences (India)

    ) model, invoked for the high density laser plasma under study. Some interesting results pertaining to the analysis of plume structure and spatio-temporal behaviour ofTe and ne along the plume length will be presented and discussed.

  6. Spectroscopic studies of laser ablation plumes of artwork materials

    Science.gov (United States)

    Oujja, M.; Rebollar, E.; Castillejo, M.

    2003-04-01

    Studies on the plasma plume created during KrF laser (248 nm) ablation of dosimeter tempera samples in vacuum have been carried out to investigate the basic interactions of the laser with paint materials. Time resolved optical emission spectroscopy (OES) was used to measure the translational velocity of electronically excited transients in the plasma plume. Laser-induced fluorescence (LIF) studies using a probe dye laser, allowed to determine the velocities of non-emitting species. The propagation velocities of C 2 in the a 3π u and d 3π g electronic states and of excited atomic species are indicative of a high translational temperature. Differences between the velocities of organic and inorganic species and between emissions from the tempera systems and from the pigments as pellets allow to discuss the participation of photochemical mechanisms in the laser irradiation of the paint systems.

  7. A comparison of the characteristics of excimer and femtosecond laser ablation of acrylonitrile butadiene styrene (ABS)

    Science.gov (United States)

    See, Tian Long; Liu, Zhu; Li, Lin; Zhong, Xiang Li

    2016-02-01

    This paper presents an investigation on the ablation characteristics of excimer laser (λ = 248 nm, τ = 15 ns) and femtosecond laser (λ = 800 nm, τ = 100 fs) on ABS polymer sheets. The laser-material interaction parameters (ablation threshold, optical penetration depth and incubation factor) and the changes in material chemical properties were evaluated and compared between the two lasers. The work shows that the ablation threshold and effective optical penetration depth values are dependent on the wavelength of laser beam (photon energy) and the pulse width. The ablation threshold value is lower for the excimer laser ablation of ABS (Fth = 0.087 J/cm2) than that for the femtosecond laser ablation of ABS (Fth = 1.576 J/cm2), demonstrating a more dominating role of laser wavelength than the pulse width in influencing the ablation threshold. The ablation depth versus the logarithmic scale of laser fluence shows two linear regions for the fs laser ablation, not previously known for polymers. The effective optical penetration depth value is lower for excimer laser ablation (α-1 = 223 nm) than that for femtosecond laser ablation (α-1 = 2917 nm). The ablation threshold decreases with increasing number of pulses (NOP) due to the chain scission process that shortens the polymeric chains, resulting in a weaker polymeric configuration and the dependency is governed by the incubation factor. Excimer laser treatment of ABS eliminates the Cdbnd C bond completely through the chain scission process whereas Cdbnd C bond is partially eliminated through the femtosecond laser treatment due to the difference in photon energy of the two laser beams. A reduction in the Cdbnd C bond through the chain scission process creates free radical carbons which then form crosslinks with each other or react with oxygen, nitrogen and water in air producing oxygen-rich (Csbnd O and Cdbnd O bond) and nitrogen-rich (Csbnd N) functional groups.

  8. Polymers designed for laser ablation-influence of photochemical properties

    International Nuclear Information System (INIS)

    Lippert, T.; Dickinson, J.T.; Hauer, M.; Kopitkovas, G.; Langford, S.C.; Masuhara, H.; Nuyken, O.; Robert, J.; Salmio, H.; Tada, T.; Tomita, K.; Wokaun, A.

    2002-01-01

    The ablation characteristics of various polymers were studied at low and high fluences. The polymers can be divided into three groups, i.e. polymers containing triazene and ester groups, the same polymers without the triazene group, and polyimide as reference polymer. At high fluences similar ablation parameters, i.e. etch rates and effective absorption coefficients, were obtained for all polymers. The main difference is the absence of carbon deposits for the designed polymers. At low fluences (at 308 nm) very pronounced differences are detected. The polymers containing the photochemically most active group (triazene) exhibit the lowest threshold of ablation (as low as 25 mJ cm -2 ) and the highest etch rates (up to 3 μm/pulse), followed by the designed polyesters and then polyimide. The laser-induced decomposition of the designed polymers was studied by nanosecond-interferometry. Only the triazene-polymer reveals etching without any sign of surface swelling, which is observed for all other polymers. The etching of the triazene-polymer starts and ends with the laser pulse, clearly indicating photochemical etching. The triazene-polymer was also studied by time-of-flight mass spectrometry (TOF-MS). The intensities of the ablation fragments show pronounced differences between irradiation at the absorption band of the triazene group (308 nm) and irradiation at a shorter wavelength (248 nm)

  9. Analysis of fabric materials cut using ultraviolet laser ablation

    Science.gov (United States)

    Tsai, Hsin-Yi; Yang, Chih-Chung; Hsiao, Wen-Tse; Huang, Kuo-Cheng; Andrew Yeh, J.

    2016-04-01

    Laser ablation technology has widely been applied in the clothing industry in recent years. However, the laser mechanism would affect the quality of fabric contours and its components. Hence, this study examined carbonization and oxidation conditions and contour variation in nonwoven, cotton, and composite leather fabrics cut by using an ultraviolet laser at a wavelength of 355 nm. Processing parameters such as laser power, pulse frequency, scanning speed, and number of pulses per spot were adjusted to investigate component variation of the materials and to determine suitable cutting parameters for the fabrics. The experimental results showed that the weights of the component changed substantially by pulse frequency but slightly by laser power, so pulse frequency of 100 kHz and laser power of 14 W were the approximate parameters for three fabrics for the smaller carbonization and a sufficient energy for rapidly cutting, which the pulse duration of laser system was fixed at 300 μs and laser irradiance was 0.98 J/mm2 simultaneously. In addition, the etiolate phenomenon of nonwoven was reduced, and the component weight of cotton and composite leather was closed to the value of knife-cut fabric as the scanning speed increased. The approximate scanning speed for nonwoven and composite leather was 200 mm/s, and one for cotton was 150 mm/s, respectively. The sharper and firmer edge is obtained by laser ablation mechanism in comparison with traditional knife cutting. Experimental results can serve as the reference for laser cutting in the clothing industry, for rapidly providing smoother patterns with lower carbonization and oxidation edge in the fashion industry.

  10. Laser ablation of lysozyme with UV, visible and infrared femto- and nanosecond pulses

    OpenAIRE

    Schou, Jørgen; Canulescu, Stela; Matei, Andreea; Cazzaniga, Andrea Carlo; Constantinescu, Catalin; Amoruso, S.; Wang, X.; Bruzzese, R.; Dinescu, M.

    2013-01-01

    Lysozyme is an interesting molecule for laser ablation of organic materials, because the ablation has been comprehensively studied, it is a medium heavy molecule with a mass of 14305 Da, which can be detected by standard techniques, and because it is used as a bactericidal protein in the food industry. Lysozyme molecules do not absorb energy for wavelengths above 310 nm, but nevertheless there is a strong mass loss by ablation for laser irradiation in the visible regime. The total ablation yi...

  11. Precise femtosecond laser ablation of dental hard tissue: preliminary investigation on adequate laser parameters

    International Nuclear Information System (INIS)

    Hikov, Todor; Pecheva, Emilia; Petrov, Todor; Montgomery, Paul; Antoni, Frederic; Leong-Hoi, Audrey

    2017-01-01

    This work aims at evaluating the possibility of introducing state-of-the-art commercial femtosecond laser system in restorative dentistry by maintaining well-known benefits of lasers for caries removal, but also in overcoming disadvantages such as thermal damage of irradiated substrate. Femtosecond ablation of dental hard tissue is investigated by changing the irradiation parameters (pulsed laser energy, scanning speed and pulse repetition rate), assessed for enamel and dentin. The femtosecond laser system used in this work may be suitable for cavity preparation in dentin and enamel, due to the expected effective ablation and low temperature increase when using ultra short laser pulses. If adequate laser parameters are selected, this system seems to be promising for promoting a laser-assisted, minimally invasive approach in restorative dentistry. (paper)

  12. Precise femtosecond laser ablation of dental hard tissue: preliminary investigation on adequate laser parameters

    Science.gov (United States)

    Hikov, Todor; Pecheva, Emilia; Montgomery, Paul; Antoni, Frederic; Leong-Hoi, Audrey; Petrov, Todor

    2017-01-01

    This work aims at evaluating the possibility of introducing state-of-the-art commercial femtosecond laser system in restorative dentistry by maintaining well-known benefits of lasers for caries removal, but also in overcoming disadvantages such as thermal damage of irradiated substrate. Femtosecond ablation of dental hard tissue is investigated by changing the irradiation parameters (pulsed laser energy, scanning speed and pulse repetition rate), assessed for enamel and dentin. The femtosecond laser system used in this work may be suitable for cavity preparation in dentin and enamel, due to the expected effective ablation and low temperature increase when using ultra short laser pulses. If adequate laser parameters are selected, this system seems to be promising for promoting a laser-assisted, minimally invasive approach in restorative dentistry.

  13. Laser ablation synthesis of monodispersed magnetic alloy nanoparticles

    International Nuclear Information System (INIS)

    Seto, Takafumi; Koga, Kenji; Akinaga, Hiroyuki; Takano, Fumiyoshi; Orii, Takaaki; Hirasawa, Makoto

    2006-01-01

    Monodispersed CoPt alloy nanoparticles were synthesized by a pulsed laser ablation (PLA) technique coupled with a low-pressure operating differential mobility analyzer (LP-DMA). The CoPt alloy nanoparticles were generated by laser ablating a solid Co-Pt target. In CoPt alloy nanoparticles synthesized from a target with a Co composition of 75 at%, the nanoparticle surfaces were covered by an oxide layer and exhibited a core-shell structure. In contrast, no shell was observed in particles generated from a target with a Co:Pt ratio of 50:50 at%. According to an EDX analysis, the compositions of the individual nanoparticles were almost the same as that of the target material. Finally, the magnetic hysteresis loops of the CoPt alloy nanoparticles exhibited ferromagnetism

  14. Laser Ablation Experiments on the Tamdakht H5 Chondrite

    Science.gov (United States)

    White, Susan M.; Stern, Eric

    2017-01-01

    High-powered lasers were used to induce ablation and to form fusion crusts in the lab on Tamdakht H5 chondrites and basalt. These ground tests were undertaken to improve our understanding, and ultimately improve our abilty to model and predict, meteoroid ablation during atmospheric entry. The infrared fiber laser at the LHMEL facilty, operated in the continuous wave (i.e. non-pulsed) mode, provided radiation surface heat flux at levels similar to meteor entry for these tests. Results are presented from the first round of testing on samples of Tamdakht H5 ordinary chondrite which were ex-posed to entry-relevant heating rates between 2 and 10 kWcm2.

  15. Nanostructured films of metal particles obtained by laser ablation

    International Nuclear Information System (INIS)

    Muniz-Miranda, M.; Gellini, C.; Giorgetti, E.; Margheri, G.; Marsili, P.; Lascialfari, L.; Becucci, L.; Trigari, S.; Giammanco, F.

    2013-01-01

    Colloidal dispersions of silver and gold nanoparticles were obtained in pure water by ablation with nanosecond pulsed laser. Then, by filtration of the metal particles on alumina, we fabricated nanostructured films, whose surface morphology was examined by atomic force microscopy (AFM) and related to surface-enhanced Raman scattering (SERS) after adsorption of adenine. - Highlights: • Ag and Au colloidal nanoparticles were obtained by laser ablation. • Nanostructured Ag and Au films were fabricated by filtration of metal nanoparticles. • Surface morphology of metal films was investigated by atomic force microscopy. • Surface-enhanced Raman spectra (SERS) of adenine on metal films were obtained. • SERS enhancements were related to the surface roughness of the metal films

  16. Carbon nanotubes/laser ablation gold nanoparticles composites

    International Nuclear Information System (INIS)

    Lascialfari, Luisa; Marsili, Paolo; Caporali, Stefano; Muniz-Miranda, Maurizio; Margheri, Giancarlo; Serafini, Andrea; Brandi, Alberto; Giorgetti, Emilia; Cicchi, Stefano

    2014-01-01

    The production of nanohybrids formed by oxidized multiwalled carbon nanotubes (MWCNTs) and nanoparticles, produced by pulsed laser ablation in liquids process, is described. The use of linkers, obtained by transformation of pyrene-1-butanol, is mandatory to generate an efficient and stable interaction between the two components. Transmission electron microscopy and X-ray photoelectron spectroscopy analysis showed the obtainment of the efficient coverage of the MWCNTs by nanoparticles composed by metal gold and, partially, by oxides. - Highlights: • Laser ablation is a used for the production of gold nanoparticle colloids • An efficient decoration of carbon nanotubes with nanoparticles is obtained through the use of a linker • This method allows an efficient and tunable preparation of carbon nanotube hybrids

  17. Carbon nanotubes/laser ablation gold nanoparticles composites

    Energy Technology Data Exchange (ETDEWEB)

    Lascialfari, Luisa [Department of Chemistry, Università di Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, Firenze 50019 (Italy); Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, via Madonna del Piano 10, Sesto Fiorentino, Firenze 50019 (Italy); Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), Via Giusti 9, Firenze 50123 (Italy); Marsili, Paolo [Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, via Madonna del Piano 10, Sesto Fiorentino, Firenze 50019 (Italy); Caporali, Stefano [Department of Chemistry, Università di Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, Firenze 50019 (Italy); Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), Via Giusti 9, Firenze 50123 (Italy); Muniz-Miranda, Maurizio [Department of Chemistry, Università di Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, Firenze 50019 (Italy); Margheri, Giancarlo [Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, via Madonna del Piano 10, Sesto Fiorentino, Firenze 50019 (Italy); Serafini, Andrea; Brandi, Alberto [Department of Chemistry, Università di Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, Firenze 50019 (Italy); Giorgetti, Emilia, E-mail: emilia.giorgetti@fi.isc.cnr.it [Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, via Madonna del Piano 10, Sesto Fiorentino, Firenze 50019 (Italy); Cicchi, Stefano, E-mail: stefano.cicchi@unifi.it [Department of Chemistry, Università di Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, Firenze 50019 (Italy); Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), Via Giusti 9, Firenze 50123 (Italy)

    2014-10-31

    The production of nanohybrids formed by oxidized multiwalled carbon nanotubes (MWCNTs) and nanoparticles, produced by pulsed laser ablation in liquids process, is described. The use of linkers, obtained by transformation of pyrene-1-butanol, is mandatory to generate an efficient and stable interaction between the two components. Transmission electron microscopy and X-ray photoelectron spectroscopy analysis showed the obtainment of the efficient coverage of the MWCNTs by nanoparticles composed by metal gold and, partially, by oxides. - Highlights: • Laser ablation is a used for the production of gold nanoparticle colloids • An efficient decoration of carbon nanotubes with nanoparticles is obtained through the use of a linker • This method allows an efficient and tunable preparation of carbon nanotube hybrids.

  18. A comparison of the characteristics of excimer and femtosecond laser ablation of acrylonitrile butadiene styrene (ABS)

    Energy Technology Data Exchange (ETDEWEB)

    See, Tian Long, E-mail: tianlong.see@postgrad.manchester.ac.uk [Corrosion and Protection Centre, School of Materials, The Mill, The University of Manchester, M13 9PL Manchester (United Kingdom); Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, M13 9PL Manchester (United Kingdom); Liu, Zhu [Corrosion and Protection Centre, School of Materials, The Mill, The University of Manchester, M13 9PL Manchester (United Kingdom); Li, Lin [Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, M13 9PL Manchester (United Kingdom); Zhong, Xiang Li [Corrosion and Protection Centre, School of Materials, The Mill, The University of Manchester, M13 9PL Manchester (United Kingdom)

    2016-02-28

    Highlights: • Ablation threshold for excimer laser is lower compared to femtosecond laser. • Effective optical penetration depth for excimer laser is lower compared to femtosecond laser. • Two ablation characteristic regimes are observed for femtosecond laser ablation. • Reduction of C=C bond following excimer or fs laser ablation is observed. • Addition of oxygen- and nitrogen-rich functional groups is observed. - Abstract: This paper presents an investigation on the ablation characteristics of excimer laser (λ = 248 nm, τ = 15 ns) and femtosecond laser (λ = 800 nm, τ = 100 fs) on ABS polymer sheets. The laser–material interaction parameters (ablation threshold, optical penetration depth and incubation factor) and the changes in material chemical properties were evaluated and compared between the two lasers. The work shows that the ablation threshold and effective optical penetration depth values are dependent on the wavelength of laser beam (photon energy) and the pulse width. The ablation threshold value is lower for the excimer laser ablation of ABS (F{sub th} = 0.087 J/cm{sup 2}) than that for the femtosecond laser ablation of ABS (F{sub th} = 1.576 J/cm{sup 2}), demonstrating a more dominating role of laser wavelength than the pulse width in influencing the ablation threshold. The ablation depth versus the logarithmic scale of laser fluence shows two linear regions for the fs laser ablation, not previously known for polymers. The effective optical penetration depth value is lower for excimer laser ablation (α{sup −1} = 223 nm) than that for femtosecond laser ablation (α{sup −1} = 2917 nm). The ablation threshold decreases with increasing number of pulses (NOP) due to the chain scission process that shortens the polymeric chains, resulting in a weaker polymeric configuration and the dependency is governed by the incubation factor. Excimer laser treatment of ABS eliminates the C=C bond completely through the chain scission process whereas

  19. Aerospace propulsion using laser-driven plasma generator

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Daozhi (Beijing Univ. of Aeronautics and Astronautics (People' s Republic of China))

    1989-04-01

    The use of a remote pulsed laser beam for aerospace vehicle propulsion is suggested. The engine will be of variable cycle type using a plasma generator, and the vehicle will be of rotary plate type. It will be launched using an external radiated-heated VTOL thruster, lifted by an MHD fanjet, and accelerated by a rotary rocket pulsejet. It is speculated that, sending the same payload into low earth orbit, the vehicle mass at liftoff will be 1/20th that of the Space Shuttle, and the propellant mass carried by the new vehicle will be only 1/40th that of the Shuttle. 40 refs.

  20. Laser ablation of molecular carbon nitride compounds

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, D., E-mail: d.fischer@fkf.mpg.de [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Schwinghammer, K. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Department of Chemistry, University of Munich, LMU, Butenandtstr. 5-13, 81377 Munich (Germany); Nanosystems Initiative Munich (NIM) and Center for Nanoscience (CeNS), 80799 Munich (Germany); Sondermann, C. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Department of Chemistry, University of Munich, LMU, Butenandtstr. 5-13, 81377 Munich (Germany); Lau, V.W.; Mannhart, J. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Lotsch, B.V. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Department of Chemistry, University of Munich, LMU, Butenandtstr. 5-13, 81377 Munich (Germany); Nanosystems Initiative Munich (NIM) and Center for Nanoscience (CeNS), 80799 Munich (Germany)

    2015-09-15

    We present a method for the preparation of thin films on sapphire substrates of the carbon nitride precursors dicyandiamide (C{sub 2}N{sub 4}H{sub 4}), melamine (C{sub 3}N{sub 6}H{sub 6}), and melem (C{sub 6}N{sub 10}H{sub 6}), using the femtosecond-pulsed laser deposition technique (femto-PLD) at different temperatures. The depositions were carried out under high vacuum with a femtosecond-pulsed laser. The focused laser beam is scanned on the surface of a rotating target consisting of the pelletized compounds. The resulting polycrystalline, opaque films were characterized by X-ray powder diffraction, infrared, Raman, and X-ray photoelectron spectroscopy, photoluminescence, SEM, and MALDI-TOF mass spectrometry measurements. The crystal structures and optical/spectroscopic results of the obtained rough films largely match those of the bulk materials.

  1. Negative ion production by laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Wada, Motoi [Doshisha Univ., Tanabe, Kyoto (Japan). Faculty of Engineering; Sasao, Mamiko

    1997-02-01

    The status of the development of Li{sup -} production by generating a neutral Li flux with an intense radiation of a laser beam onto the surface of Li metal has been reported. The experimental apparatus was arranged to detect a mass separated Li{sup +} and Li{sup -} ion beams. A Li sputtering probe, immersed in the extraction region of a compact (6cm diam. 7cm long) magnetic multipole ion source was irradiated with a Nd-YAG laser of 0.4 J/pulse. The production of mass-separated positive ions of Li by laser irradiation has been confirmed, but the production of Li{sup -} has not been confirmed yet due to the noise caused by a temporal discharge. (author)

  2. Growth of epitaxial thin films by pulsed laser ablation

    International Nuclear Information System (INIS)

    Lowndes, D.H.

    1992-01-01

    High-quality, high-temperature superconductor (HTSc) films can be grown by the pulsed laser ablation (PLA) process. This article provides a detailed introduction to the advantages and curent limitations of PLA for epitaxial film growth. Emphasis is placed on experimental methods and on exploitation of PLA to control epitaxial growth at either the unit cell or the atomic-layer level. Examples are taken from recent HTSc film growth. 33 figs, 127 refs

  3. Laser ablation of Bi-substituted gadolinium iron garnet films

    International Nuclear Information System (INIS)

    Watanabe, N.; Hayashida, K.; Kawano, K.; Higuchi, K.; Ohkoshi, M.; Tsushima, K.

    1995-01-01

    Bi-substituted gadolinium iron garnet films were deposited by laser ablation. The composition, the structure and the magnetic properties of the films were found to be strongly dependent both on the compositions of the targets and on the pressure of oxygen. The highest values of Bi-substitution up to x=1.44 with uniform composition were obtained, after annealing in air. ((orig.))

  4. Characteristics of target polarization by laser ablation

    Czech Academy of Sciences Publication Activity Database

    Krása, Josef; Delle Side, D.; Giuffreda, E.; Nassisi, V.

    2015-01-01

    Roč. 33, č. 4 (2015), 601-605 ISSN 0263-0346 R&D Projects: GA ČR GAP205/12/0454; GA MŠk EE2.3.20.0279 Grant - others: Laser Zdroj (OP VK 3)(XE) CZ.1.07/2.3.00/20.0279 Institutional support: RVO:68378271 Keywords : Target current in laser -produced plasmas * positive and negative target polarization * space structure of ion front Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.649, year: 2015

  5. Tactile Sensing From Laser-Ablated Metallized PET Films

    KAUST Repository

    Nag, Anindya

    2016-10-17

    This paper reports the design, fabrication, and implementation of a novel sensor patch developed from commercial polyethylene terephthalate films metallized with aluminum on one side. The aluminum was ablated with laser to form interdigitated electrodes to make sensor prototypes. The interdigitated electrodes were patterned on the substrate with a laser cutter. Characterization of the prototypes was done to determine their operating frequency followed by experimentation. The prototypes have been used as a tactile sensor showing promising results for using these patches in applications with contact pressures considerably lesser than normal human contact pressure.

  6. Laser ablation deposition measurements from silver and nickel

    DEFF Research Database (Denmark)

    Svendsen, Winnie Edith; Ellegaard, Ole; Schou, Jørgen

    1996-01-01

    The deposition rate for laser ablated metals has been studied in a standard geometry for fluences up to 20 J/cm(2). The rate for silver and nickel is a few percent of a monolayer per pulse at the laser wavelengths 532 nm and 355 nm. The rate for nickel is significantly higher than that for silver...... at 532 nm, whereas the rate for the two metals is similar at 355 nm. This behaviour disagrees with calculations based on the thermal properties at low intensities as well as predictions based on formation of an absorbing plasma at high intensities. The deposition rate falls strongly with increasing...

  7. Optical Thomson scatter from laser-ablated plumes

    International Nuclear Information System (INIS)

    Delserieys, A.; Khattak, F. Y.; Lewis, C. L. S.; Riley, D.; Pedregosa Gutierrez, J.

    2008-01-01

    We have obtained density and temperature informations on an expanding KrF laser-ablated magnesium plume via optical Thomson scatter with a frequency doubled Nd:YAG laser. The electron temperature was found to decay with the expected T e ∝t -1 dependence. However, we have found the electron density to have a time dependence n e ∝t -4.95 which can be explained by strong recombination processes. We also observed atomic Raman satellites originating from transitions between the different angular momentum levels of the metastable 3 P 0 term in Mg I

  8. Plasma dynamics from laser ablated solid lithium

    Indian Academy of Sciences (India)

    ture with respect to an appropriate theoretical plasma model. For a high density laser plasma one invokes the concept of local thermodynamic equilibrium (LTE) as a model to explain the atomic collision processes [4]. The experimental results when fitted to the proposed model, will validate the assumptions underlying the ...

  9. Polarization of plastic targets by laser ablation

    Czech Academy of Sciences Publication Activity Database

    Giuffreda, E.; Delle Side, D.; Krása, Josef; Nassisi, V.

    2016-01-01

    Roč. 11, May (2016), s. 1-6, č. článku C05004. ISSN 1748-0221 Institutional support: RVO:68378271 Keywords : lasers * ion sources * wake-field acceleration Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.220, year: 2016

  10. Reassembling Solid Materials by Femtosecond Laser Ablation: Case of Aluminum Nitride

    Science.gov (United States)

    Kobayashi, Tohru; Matsuo, Yukari

    2013-06-01

    Through atomization and ionization, we could completely alter the composition of a nonconductive material, aluminum nitride, by femtosecond laser ablation. Preferential production of pure aluminum cluster cations Aln+ (n≤32) reflects not only their higher energetic stability compared with mixed clusters AlnNm+ but also completion of thermal relaxation in ablation plasma. Observation of metastable dissociation of Aln+ indicates that cluster cations have still enough internal energy for dissociation to occur, although the process is much slower than the cluster formation. Almost no cluster formation has been observed after nanosecond laser ablation of aluminum nitride, which highlights the distinct nature of ablation plasma produced by femtosecond laser ablation.

  11. Comparison of soft and hard tissue ablation with sub-ps and ns pulse lasers

    Energy Technology Data Exchange (ETDEWEB)

    Da Silva, L.B.; Stuart, B.C.; Celliers, P.M.; Feit, M.D.; Glinsky, M.E.; Heredia, N.J.; Herman, S.; Lane, S.M.; London, R.A.; Matthews, D.L.; Perry, M.D.; Rubenchik, A.M. [Lawrence Livermore National Lab., CA (United States); Chang, T.D. [Veterans Administration Hospital, Martinez, CA (United States); Neev, J. [Beckman Laser Inst. and Medical Clinic, Irvine, CA (United States)

    1996-05-01

    Tissue ablation with ultrashort laser pulses offers several unique advantages. The nonlinear energy deposition is insensitive to tissue type, allowing this tool to be used for soft and hard tissue ablation. The localized energy deposition lead to precise ablation depth and minimal collateral damage. This paper reports on efforts to study and demonstrate tissue ablation using an ultrashort pulse laser. Ablation efficiency and extent of collateral damage for 0.3 ps and 1000 ps duration laser pulses are compared. Temperature measurements of the rear surface of a tooth section is also presented.

  12. Surface wettability of silicon substrates enhanced by laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Tseng, Shih-Feng [National Applied Research Laboratories, Instrument Technology Research Center, Hsinchu (China); National Chiao Tung University, Department of Mechanical Engineering, Hsinchu (China); Hsiao, Wen-Tse; Huang, Kuo-Cheng; Hsiao, Sheng-Yi [National Applied Research Laboratories, Instrument Technology Research Center, Hsinchu (China); Chen, Ming-Fei [National Changhua University of Education, Department of Mechatronics Engineering, Changhua (China); Lin, Yung-Sheng [Hungkuang University, Department of Applied Cosmetology and Graduate Institute of Cosmetic Science, Taichung (China); Chou, Chang-Pin [National Chiao Tung University, Department of Mechanical Engineering, Hsinchu (China)

    2010-11-15

    Laser-ablation techniques have been widely applied for removing material from a solid surface using a laser-beam irradiating apparatus. This paper presents a surface-texturing technique to create rough patterns on a silicon substrate using a pulsed Nd:YAG laser system. The different degrees of microstructure and surface roughness were adjusted by the laser fluence and laser pulse duration. A scanning electron microscope (SEM) and a 3D confocal laser-scanning microscope are used to measure the surface micrograph and roughness of the patterns, respectively. The contact angle variations between droplets on the textured surface were measured using an FTA 188 video contact angle analyzer. The results indicate that increasing the values of laser fluence and laser pulse duration pushes more molten slag piled around these patterns to create micro-sized craters and leads to an increase in the crater height and surface roughness. A typical example of a droplet on a laser-textured surface shows that the droplet spreads very quickly and almost disappears within 0.5167 s, compared to a contact angle of 47.9 on an untextured surface. This processing technique can also be applied to fabricating Si solar panels to increase the absorption efficiency of light. (orig.)

  13. Laser ablation of hard tissue: correlation between the laser beam parameters and the post-ablative tissue characteristics

    Science.gov (United States)

    Serafetinides, Alexandros A.; Makropoulou, Mersini I.; Khabbaz, Maruan

    2003-11-01

    Hard dental tissue laser applications, such as preventive treatment, laser diagnosis of caries, laser etching of enamel, laser decay removal and cavity preparation, and more recently use of the laser light to enlarge the root canal during the endodontic therapy, have been investigated for in vitro and in vivo applications. Post-ablative surface characteristics, e.g. degree of charring, cracks and other surface deformation, can be evaluated using scanning electron microscopy. The experimental data are discussed in relevance with the laser beam characteristics, e.g. pulse duration, beam profile, and the beam delivery systems employed. Techniques based on the laser illumination of the dental tissues and the subsequent evaluation of the scattered fluorescent light will be a valuable tool in early diagnosis of tooth diseases, as carious dentin or enamel. The laser induced autofluorescence signal of healthy dentin is much stronger than that of the carious dentin. However, a better understanding of the transmission patterns of laser light in teeth, for both diagnosis and therapy is needed, before the laser procedures can be used in a clinical environment.

  14. Ablation of biological tissues by radiation of strontium vapor laser

    Energy Technology Data Exchange (ETDEWEB)

    Soldatov, A. N., E-mail: general@tic.tsu.ru; Vasilieva, A. V., E-mail: anita-tomsk@mail.ru [National Research Tomsk State University, Lenin ave., 36, 634050, Tomsk (Russian Federation)

    2015-11-17

    A two-stage laser system consisting of a master oscillator and a power amplifier based on sources of self- contained transitions in pairs SrI and SrII has been developed. The radiation spectrum contains 8 laser lines generating in the range of 1 – 6.45 μm, with a generation pulse length of 50 – 150 ns, and pulse energy of ∼ 2.5 mJ. The divergence of the output beam was close to the diffraction and did not exceed 0.5 mrad. The control range of the laser pulse repetition rate varied from 10 to 15 000 Hz. The given laser system has allowed to perform ablation of bone tissue samples without visible thermal damage.

  15. Nanostructuring of ITO thin films through femtosecond laser ablation

    Science.gov (United States)

    Sahin, Ramazan; Kabacelik, Ismail

    2016-04-01

    Due to reduced thermal effects, tightly focused femtosecond laser beams can yield submicron resolution with minimal side effects. In laser direct writing applications, diffraction-free nature of the Bessel beams relaxes alignment of the sample and shortens the production time. Micron-sized central spots and long depth of focused beams can be simultaneously produced. We apply fs Bessel beam single-pulse ablation method to transparent conductive oxide films. We use laser of 1030 nm wavelength and two different axicons (base angles are 25° and 40°). Fabricated structures are characterized by optical microscope, atomic force microscope and scanning electron microscope. Laser beam shaping and virtues of non-diffracted Bessel beams provide periodic structures for scribing in the solar cells or high-resolution displays and reduce the process time.

  16. Corneal topograph-guided laser subepithelial keratomileusis (LASEK) corrects decentered ablation after laser in situ.

    Science.gov (United States)

    Yu, Ke Ming; Zhang, Jing; Luo, Hui Hui

    2012-12-01

    Corneal topograph-guided laser subepithelial keratomileusis (LASEK) can effectively correct decentered ablation occurring post laser in situ keratomileusis (LASIK) and to enhance our understanding and diagnosis of decentered ablation following LASIK. Previous studies in the relevant literature are reviewed, and a case report is provided. A patient with high myopia undergoing LASIK in both eyes presented with distorted vision in the left eye, which interfered with the vision in the right eye and caused blurred vision in both eyes. The patient was unable to see objects with both eyes. After receiving corneal topography-guided LASEK, the signs of distorted vision in the left eye and bilateral blurred vision were significantly alleviated, and the patient could see objects with both eyes simultaneously. Clinical ophthalmologists should be aware of the occurrence of decentered ablation after LASIK. Corneal topography-guided LASEK is an efficacious tool for correcting decentered ablation.

  17. Filamented plasmas in laser ablation of solids

    Czech Academy of Sciences Publication Activity Database

    Davies, J.R.; Fajardo, M.; Kozlová, Michaela; Mocek, Tomáš; Polan, Jiří; Rus, Bedřich

    2009-01-01

    Roč. 51, č. 3 (2009), 035013/1-035013/12 ISSN 0741-3335 EU Projects: European Commission(XE) 12843 - TUIXS Grant - others:FCT(PT) POCI/FIS/59563/2004 Institutional research plan: CEZ:AV0Z10100523 Keywords : magneto-hydrodynamic modelling * perturbation * filaments * x-ray * plasma Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.409, year: 2009

  18. A study of particle generation during laser ablation with applications

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chunyi [Univ. of California, Berkeley, CA (United States)

    2005-01-01

    A study has been made of the generation of particles during laser ablation and has included size distribution measurements and observation of the formation processes. The particle size distribution with respect to different laser parameters was obtained in-line using a differential mobility analyzer (DMA) and a particle counter. The experimental results show that the particle size varies with laser energy, laser pulsewidth, ambient gas flow rate and sample properties. The results serve as a basis for controlling the size of nanoparticles generated by laser ablation. Laser shadowgraph imaging was used to study mass ejection processes and mechanisms. At higher laser irradiance, some particles were ejected in the liquid and even in the solid phase. Time-resolved images show the propagation of the shockwaves: external shockwaves propagate outward and decelerate, and internal shockwaves reflect back and forth between the gas contact surface and the sample surface. The internal shockwave is proposed to cause the ejection of liquid particles when the internal shockwave strikes the liquid molten layer. A simulation based on vapor plume expansion was carried out and provides satisfactory agreement with experimental results. Different material properties result in different particle ejection behavior:particle ejection for most materials including metals result in a conically shaped envelope for the ejected material while ejection for silicon resembles a liquid jet. The difference in density change when the materials melt was proposed to be an important factor in the different ejection behavior. The characteristics of particles generated by laser ablation have a strong influence on the chemical analysis of the irradiated sample. Large particles are more difficult to completely vaporize and ionize, and induced preferential vaporization causes fractionation (i.e. a detected chemical composition that differs from the sample material). Large particles also result in spikes in

  19. Synthesis and Properties of Platinum Nanoparticles by Pulsed Laser Ablation in Liquid

    Directory of Open Access Journals (Sweden)

    Maria Isabel Mendivil Palma

    2016-01-01

    Full Text Available Platinum (Pt nanoparticles were synthesized by pulsed laser ablation in liquid (PLAL technique in different liquids (acetone, ethanol, and methanol. Ablation was performed using a Q-switched Nd:YAG laser with output energy of 230 mJ/pulse for 532 nm wavelength. Ablation time and laser energy fluence were varied for all the liquids. Effects of laser energy fluence, ablation time, and nature of the liquid were reported. The mean size, size distributions, shape, elemental composition, and optical properties of Pt nanoparticles synthesized by PLAL were examined by transmission electron microscopy (TEM, X-ray photoelectron spectroscopy (XPS, and UV-Visible absorption spectroscopy.

  20. Laser ablation of liquid surface in air induced by laser irradiation through liquid medium

    Science.gov (United States)

    Utsunomiya, Yuji; Kajiwara, Takashi; Nishiyama, Takashi; Nagayama, Kunihito; Kubota, Shiro; Nakahara, Motonao

    2010-10-01

    The pulse laser ablation of a liquid surface in air when induced by laser irradiation through a liquid medium has been experimentally investigated. A supersonic liquid jet is observed at the liquid-air interface. The liquid surface layer is driven by a plasma plume that is produced by laser ablation at the layer, resulting in a liquid jet. This phenomenon occurs only when an Nd:YAG laser pulse (wavelength: 1064 nm) is focused from the liquid onto air at a low fluence of 20 J/cm2. In this case, as Fresnel’s law shows, the incident and reflected electric fields near the liquid surface layer are superposed constructively. In contrast, when the incident laser is focused from air onto the liquid, a liquid jet is produced only at an extremely high fluence, several times larger than that in the former case. The similarities and differences in the liquid jets and atomization processes are studied for several liquid samples, including water, ethanol, and vacuum oil. The laser ablation of the liquid surface is found to depend on the incident laser energy and laser fluence. A pulse laser light source and high-resolution film are required to observe the detailed structure of a liquid jet.

  1. Laser ablative synthesis of carbon nanotubes

    Science.gov (United States)

    Smith, Michael W.; Jordan, Kevin; Park, Cheol

    2010-03-02

    An improved method for the production of single walled carbon nanotubes that utilizes an RF-induction heated side-pumped synthesis chamber for the production of such. Such a method, while capable of producing large volumes of carbon nanotubes, concurrently permits the use of a simplified apparatus that allows for greatly reduced heat up and cool down times and flexible flowpaths that can be readily modified for production efficiency optimization. The method of the present invention utilizes a free electron laser operating at high average and peak fluence to illuminate a rotating and translating graphite/catalyst target to obtain high yields of SWNTs without the use of a vacuum chamber.

  2. Soft x-ray laser ablation of metals and dielectrics

    Science.gov (United States)

    Faenov, A.; Pikuz, T.; Ishino, M.; Inogamov, N.; Zhakhovsky, V.; Skobelev, I.; Hasegawa, N.; Nishikino, M.; Kando, M.; Kodama, R.; Kawachi, T.

    2017-05-01

    We present an overview of our systematic studies of the surface modifications resulting from the interactions of both single and multiple picosecond soft x-ray laser (SXRL) pulses with materials, such as gold (Au), copper (Cu), aluminum (Al), and lithium fluoride (LiF). We show experimentally the possibility of the precise nanometer size structures ( 10-40 nm) formation on their surfaces by ultra-low ( 10-30 mJ/cm2 ) fluencies of single picosecond SXRL pulse. Comparison experimental results with the atomistic model of ablation, which was developed for the single SXRL shot interaction with dielectrics and metals, is provided. Theoretical description of surface nanostructures is considered and is shown that such structures are formed after laser illumination in a process of mechanical spallation of ultrathin surface layer of molten metal. Spallation is accompanied by a strong foaming of melt, breaking of foam, and freezing of foam remnants. Those remnants form chaotic nanostructures, which are observed in experiments. Our measurements show that electron temperature of matter under irradiation of SXRL was lower than 1 eV. The model calculation also predicts that the ablation induced by the SXRL can create the significant low electron temperature. Our results demonstrate that tensile stress created in LiF and metals by short SXRL pulse can produce spallative ablation of target even for drastically small fluencies, which open new opportunities for material nano processing.

  3. Low density, non-ablative fractional CO2 laser rejuvenation.

    Science.gov (United States)

    Christiansen, Kaare; Bjerring, Peter

    2008-09-01

    Fractional skin rejuvenation has gained increased interest since its introduction in 2003. Both non-ablative and ablative lasers as well as different treatment techniques have been devised. Recent clinical studies indicate that a paradigm of low spot density combined with high fluences tend to produce better clinical results and less risk of post-inflammatory hyperpigmentation in darker skin types. The present study is focused on investigations of the clinical outcome by non-ablative fractional CO(2) treatments with a single pass with low spot density. A CO(2) laser was equipped with a scanner enabling it to perform fractional treatments with 36, 64 or 100 microthermal zones (MTZ)/cm(2). Twelve patients participated in the study. The perioral area was treated three times with 1-month intervals using a spot density of 64 MTZ/cm(2), a spot diameter of 0.5 mm, a micro-beam energy of 36-60 mJ, and a pulse duration of 3-5 milliseconds. Follow-up was performed 3 months after the last treatment. At the 3-month follow-up 72.7% of the volunteers had obtained improvement in ultrasonographically determined dermal density, and the average improvement was 40.2% (SD: 48.0%). This improvement was statistically significant (Plaser treatments.

  4. Resonant holographic measurements of laser ablation plume expansion in vacuum and argon gas backgrounds

    Energy Technology Data Exchange (ETDEWEB)

    Lindley, Roger Alan [Michigan Univ., Ann Arbor, MI (United States)

    1993-01-01

    This thesis discusses the following on resonant holographic measurements of laser ablation plume expansion: Introduction to laser ablation; applications of laser ablation; The study of plume expansion; holographic interferometry; resonant holographic interferometry; accounting for finite laser bandwidth; The solution for doppler broadening and finite bandwidth; the main optical table; the lumonics laser spot shape; developing and reconstructing the holograms; plume expansion in RF/Plasma Environments; Determining λ°; resonant refraction effects; fringe shift interpretation; shot-to-shot consistency; laser ablation in vacuum and low pressure, inert, background gas; theoretically modeling plume expansion in vacuum and low pressure, inert, background gas; and laser ablation in higher pressure, inert, background gas.

  5. Time-resolved diagnostics of excimer laser-generated ablation plasmas used for pulsed laser deposition

    International Nuclear Information System (INIS)

    Geohegan, D.B.

    1994-01-01

    Characteristics of laser plasmas used for pulsed laser deposition (PLD) of thin films are examined with four in situ diagnostic techniques: Optical emission spectroscopy, optical absorption spectroscopy, ion probe studies, and gated ICCD (intensified charge-coupled-device array) fast photography. These four techniques are complementary and permit simultaneous views of the transport of ions, excited states, ground state neutrals and ions, and hot particulates following KrF laser ablation of YBCO, BN, graphite and Si in vacuum and background gases. The implementation and advantages of the four techniques are first described in order to introduce the key features of laser plasmas for pulsed laser deposition. Aspects of the interaction of the ablation plume with background gases (i.e., thermalization, attenuation, shock formation) and the collision of the plasma plume with the substrate heater are then summarized. The techniques of fast ICCD photography and gated photon counting are then applied to investigate the temperature, velocity, and spatial distribution of hot particles generated during KrF ablation of YBCO, BN, Si and graphite. Finally, key features of fast imaging of the laser ablation of graphite into high pressure rare gases are presented in order to elucidate internal reflected shocks within the plume, redeposition of material on a surface, and formation of hot nanoparticles within the plume

  6. Time-resolved diagnostics of excimer laser-generated ablation plasmas used for pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Geohegan, D.B.

    1994-09-01

    Characteristics of laser plasmas used for pulsed laser deposition (PLD) of thin films are examined with four in situ diagnostic techniques: Optical emission spectroscopy, optical absorption spectroscopy, ion probe studies, and gated ICCD (intensified charge-coupled-device array) fast photography. These four techniques are complementary and permit simultaneous views of the transport of ions, excited states, ground state neutrals and ions, and hot particulates following KrF laser ablation of YBCO, BN, graphite and Si in vacuum and background gases. The implementation and advantages of the four techniques are first described in order to introduce the key features of laser plasmas for pulsed laser deposition. Aspects of the interaction of the ablation plume with background gases (i.e., thermalization, attenuation, shock formation) and the collision of the plasma plume with the substrate heater are then summarized. The techniques of fast ICCD photography and gated photon counting are then applied to investigate the temperature, velocity, and spatial distribution of hot particles generated during KrF ablation of YBCO, BN, Si and graphite. Finally, key features of fast imaging of the laser ablation of graphite into high pressure rare gases are presented in order to elucidate internal reflected shocks within the plume, redeposition of material on a surface, and formation of hot nanoparticles within the plume.

  7. Investigation of ultrashort pulse laser ablation of solid targets by measuring the ablation-generated momentum using a torsion pendulum.

    Science.gov (United States)

    Zhang, Nan; Wang, Wentao; Zhu, Xiaonong; Liu, Jiansheng; Xu, Kuanhong; Huang, Peng; Zhao, Jiefeng; Li, Ruxin; Wang, Mingwei

    2011-04-25

    50 fs - 12 ps laser pulses are employed to ablate aluminum, copper, iron, and graphite targets. The ablation-generated momentum is measured with a torsion pendulum. Corresponding time-resolved shadowgraphic measurements show that the ablation process at the optimal laser fluence achieving the maximal momentum is primarily dominated by the photomechanical mechanism. When laser pulses with specific laser fluence are used and the pulse duration is tuned from 50 fs to 12 ps, the generated momentum firstly increases and then remains almost constant, which could be attributed to the change of the ablation mechanism involved from atomization to phase explosion. The investigation of the ablation-generated momentum also reveals a nonlinear momentum-energy conversion scaling law, namely, as the pulse energy increases, the momentum obtained by the target increases nonlinearly. This may be caused by the effective reduction of the dissipated energy into the surrounding of the ablation zone as the pulse energy increases, which indicates that for femtosecond laser the dissipated energy into the surrounding target is still significant.

  8. Laser applications in nanotechnology: nanofabrication using laser ablation and laser nanolithography

    International Nuclear Information System (INIS)

    Makarov, G N

    2013-01-01

    The fact that nanoparticles and nanomaterials have fundamental properties different both from their constituent atoms or molecules and from their bulk counterparts has stimulated great interest, both theoretical and practical, in nanoparticles and nanoparticle-based assemblies (functional materials), with the result that these structures have become the subject of explosive research over the last twenty years or so. A great deal of progress in this field has relied on the use of lasers. In this paper, the directions followed and results obtained in laser nanotechnology research are reviewed. The parameters, properties, and applications of nanoparticles are discussed, along with the physical and chemical methods for their fabrication and investigation. Nanofabrication applications of and fundamental physical principles behind laser ablation and laser nanolithography are discussed in detail. The applications of laser radiation are shown to range from fabricating, melting, and evaporating nanoparticles to changing their shape, structure, size, and size distribution, through studying their dynamics and forming them into periodic arrays and various structures and assemblies. The historical development of research on nanoparticles and nanomaterials and the application of laser nanotechnology in various fields are briefly reviewed. (reviews of topical problems)

  9. The influence of laser-particle interaction in laser induced breakdown spectroscopy and laser ablation inductively coupled plasma spectrometry

    Science.gov (United States)

    Lindner, Helmut; Loper, Kristofer H.; Hahn, David W.; Niemax, Kay

    2011-02-01

    Particles produced by previous laser shots may have significant influence on the analytical signal in laser-induced breakdown spectroscopy (LIBS) and laser ablation inductively coupled plasma (LA-ICP) spectrometry if they remain close to the position of laser sampling. The effects of these particles on the laser-induced breakdown event are demonstrated in several ways. LIBS-experiments were conducted in an ablation cell at atmospheric conditions in argon or air applying a dual-pulse arrangement with orthogonal pre-pulse, i.e., plasma breakdown in a gas generated by a focussed laser beam parallel and close to the sample surface followed by a delayed crossing laser pulse in orthogonal direction which actually ablates material from the sample and produces the LIBS plasma. The optical emission of the LIBS plasma as well as the absorption of the pre-pulse laser was measured. In the presence of particles in the focus of the pre-pulse laser, the plasma breakdown is affected and more energy of the pre-pulse laser is absorbed than without particles. As a result, the analyte line emission from the LIBS plasma of the second laser is enhanced. It is assumed that the enhancement is not only due to an increase of mass ablated by the second laser but also to better atomization and excitation conditions favored by a reduced gas density in the pre-pulse plasma. Higher laser pulse frequencies increase the probability of particle-laser interaction and, therefore, reduce the shot-to-shot line intensity variation as compared to lower particle loadings in the cell. Additional experiments using an aerosol chamber were performed to further quantify the laser absorption by the plasma in dependence on time both with and without the presence of particles. The overall implication of laser-particle interactions for LIBS and LA-ICP-MS/OES are discussed.

  10. Customized ablation using an all-solid-state deep-UV laser

    Science.gov (United States)

    Korn, G.; Lenzner, M.; Kittelmann, O.; Zatonski, R.; Kirsch, M.; Kuklin, Y.

    2003-07-01

    We show first deep UV ablation results achieved with our new all solid state laser system. The system parameters allow high repetition rate ablation with a small spot diameter of about 0.250mm and a fluence of 350 mJ/cm2 at a wavelength of 210 nm using sequential frequency conversion of a diode pumped laser source. The single shot and multishot ablation rates as well as the ablation profiles have been defined using MicroProf (Fries Research and Technology GmbH, Germany). By means of computer controlled scanning we produce smooth ablation profiles corresponding to a correction of myopia, hyperopia or astigmatism. Due to the small spot size and high repetition rate of the laser we are able to generate in short time intervals complicated ablation profiles described by higher order polynomial functions which are required for the needs of customized corneal ablation.

  11. Production of silver nanoparticles by laser ablation in open air

    International Nuclear Information System (INIS)

    Boutinguiza, M.; Comesaña, R.; Lusquiños, F.; Riveiro, A.; Val, J. del; Pou, J.

    2015-01-01

    Highlights: • Silver nanoparticles have been obtained by laser ablation of metallic Ag in open air using nanosecond laser. • The continuous process enables increasing the production yield. • The obtained particles are rounded shape with narrow size distribution. - Abstract: Silver nanoparticles have attracted much attention as a subject of investigation due to their well-known properties, such as good conductivity, antibacterial and catalytic effects, etc. They are used in many different areas, such as medicine, industrial applications, scientific investigation, etc. There are different techniques for producing Ag nanoparticles, chemical, electrochemical, sonochemical, etc. These methods often lead to impurities together with nanoparticles or colloidal solutions. In this work, laser ablation of solids in open air conditions (LASOA) is used to produce silver nanoparticles and collect them on glass substrates. Production and deposition of silver nanoparticles are integrated in the same step to reduce the process. The obtained particles are analysed and the nanoparticles formation mechanism is discussed. The obtained nanoparticles were characterized by means of transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and UV/VIS absorption spectroscopy. The obtained nanoparticles consisted of Ag nanoparticles showing rounded shape with diameters ranging from few to 50 nm

  12. Laser ablation of posterior urethral valves by fetal cystoscopy.

    Science.gov (United States)

    Martínez, José María; Masoller, Narcis; Devlieger, Roland; Passchyn, Esther; Gómez, Olga; Rodo, Joan; Deprest, Jan A; Gratacós, Eduard

    2015-01-01

    To report the results of fetal cystoscopic laser ablation of posterior urethral valves (PUV) in a consecutive series in two referral centers. Twenty pregnant women with a presumptive isolated PUV were treated with fetal cystoscopy under local anesthesia. Identification and fulguration of the PUV by one or several firing-contacts with diode laser were attempted. Perinatal and long-term outcomes were prospectively recorded. The median gestational age at procedure was 18.1 weeks (range 15.0-25.6), and median operation time was 24 min (range 15-40). Access to the urethra was achieved in 19/20 (95%) cases, and postoperative, normalization of bladder size and amniotic fluid was observed in 16/20 (80%). Overall, there were 9 (45%) terminations of pregnancy and 11 women (55%) delivered a liveborn baby at a mean gestational age of 37.3 (29.1-40.2) weeks. No infants developed pulmonary hypoplasia and all were alive at 15-110 months. Eight (40% of all fetuses, 72.7% of newborns) had normal renal function and 3 (27.3%) had renal failure awaiting renal transplantation. Fetoscopic laser ablation for PUV can achieve bladder decompression and amniotic fluid normalization with a single procedure in selected cases with anyhydramnios. There is still a significant risk of progression to renal failure pre or postnatally. © 2014 S. Karger AG, Basel.

  13. Laser Ablation Plume Expansion In The Presence Of Charged Impurities

    International Nuclear Information System (INIS)

    Djebli, M.

    2008-01-01

    The expansion of plasma created by laser ablation is investigated using the fluid model. At the first stage of the expansion, electrons are considered in thermal equilibrium. The presence of highly charged impurities is considered through Poisson's equation. The set of nonlinear differential equations is solved using a moving boundary and taken into account the charge separation effect. The uniformly distributed impurities can accelerate or decelerate the ion motion depending on their charge and concentration. It is also found that the separation of the charge is valid for a specific time which depends on the impurities parameters.

  14. Laser ablation studies of solid aerosols on the Baltic coast

    Directory of Open Access Journals (Sweden)

    Robert Jaworski

    2004-09-01

    Full Text Available A Berner cascade impactor was used for the separation of solid urban aerosols in two localities of the Baltic coastal macro-region - Słupsk and Hel - in different seasons and weathers. Ten ranges of aerodynamic diameters between 0.009 and 8.11 µm were used. The elementary composition for each diameter was obtained in a complex procedure consisting of laser ablation of deposits, then their successive ionization in an inductively coupled plasma generator, and finally, mass selection in a quadrupole spectrometer. Despite its complexity, the chemical element analysis method proved to be versatile, allowing the identification air pollution from natural and industrial sources, and road traffic.

  15. Ablation characteristics of aluminum oxide and nitride ceramics during femtosecond laser micromachining

    International Nuclear Information System (INIS)

    Kim, Sung Hoon; Sohn, Ik-Bu; Jeong, Sungho

    2009-01-01

    Femtosecond laser ablation of aluminum oxide (Al 2 O 3 ) and aluminum nitride (AlN) ceramics was performed under normal atmospheric conditions (λ = 785 nm, τ p = 185 fs, repetition rate = 1 kHz), and threshold laser fluencies for single- and multi-pulse ablation were determined. The ablation characteristics of the two ceramics showed similar trends except for surface morphologies, which revealed virtually no melting in Al 2 O 3 but clear evidence of melting for AlN. Based on subsequent X-ray photoelectron spectroscopy (XPS) analyses, the chemistry of these ceramics appeared to remain the same before and after femtosecond laser ablation.

  16. Process and structures for fabrication of solar cells with laser ablation steps to form contact holes

    Science.gov (United States)

    Harley, Gabriel; Smith, David D; Dennis, Tim; Waldhauer, Ann; Kim, Taeseok; Cousins, Peter John

    2013-11-19

    Contact holes of solar cells are formed by laser ablation to accomodate various solar cell designs. Use of a laser to form the contact holes is facilitated by replacing films formed on the diffusion regions with a film that has substantially uniform thickness. Contact holes may be formed to deep diffusion regions to increase the laser ablation process margins. The laser configuration may be tailored to form contact holes through dielectric films of varying thickness.

  17. Effects of plasma confinement on the femtosecond laser ablation of silicon

    Science.gov (United States)

    Zhang, Chengyun; Yao, Jianwu; Lan, Sheng; Trofimov, Vyacheslav A.; Lysak, Tatiana M.

    2013-11-01

    We investigated the femtosecond laser ablation of silicon in a confined condition by covering the surface of a silicon wafer with a glass slide. The ablation was carried out by either irradiating the focused spot with different numbers of pulses or by scanning the laser beam on the surface of the silicon wafer. The morphology of the ablated surface was characterized by scanning electron microscope. For laser fluences much larger than the ablation threshold of silicon, cylindrical holes were generated in the confined ablation, in sharp contrast to the conical holes observed in the ablation performed in open air. Accordingly, grooves with U-shaped and V-shaped cross sections were achieved in the ablations carried out in the confined condition and in open air, respectively. For laser fluences close to the ablation threshold of silicon, the difference in the morphology of micro- and nanostructures obtained by these two ablation methods became not pronounced and two-dimensional nanohole arrays were created on the surface of silicon wafer. While the period of the nanohole arrays in the direction of the laser polarization was found to be close to the laser wavelength, the period in the direction perpendicular to the laser polarization was observed to be more than two times of the laser wavelength. In addition, the distribution of erupted nanoparticles was also found to be different in the two ablation processes. A ring-shaped distribution of nanoparticles was observed in the open air ablation while a monotonic decrease of nanoparticle density along the radial direction was found in the confined ablation.

  18. Time Resolved Shadowgraph Images of Silicon during Laser Ablation: Shockwaves and Particle Generation

    International Nuclear Information System (INIS)

    Liu, C Y; Mao, X L; Greif, R; Russo, R E

    2007-01-01

    Time resolved shadowgraph images were recorded of shockwaves and particle ejection from silicon during laser ablation. Particle ejection and expansion were correlated to an internal shockwave resonating between the shockwave front and the target surface. The number of particles ablated increased with laser energy and was related to the crater volume

  19. Time Resolved Shadowgraph Images of Silicon during Laser Ablation:Shockwaves and Particle Generation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.Y.; Mao, X.L.; Greif, R.; Russo, R.E.

    2006-05-06

    Time resolved shadowgraph images were recorded of shockwaves and particle ejection from silicon during laser ablation. Particle ejection and expansion were correlated to an internal shockwave resonating between the shockwave front and the target surface. The number of particles ablated increased with laser energy and was related to the crater volume.

  20. Ablation experiment and threshold calculation of titanium alloy irradiated by ultra-fast pulse laser

    Directory of Open Access Journals (Sweden)

    Buxiang Zheng

    2014-02-01

    Full Text Available The interaction between an ultra-fast pulse laser and a material's surface has become a research hotspot in recent years. Micromachining of titanium alloy with an ultra-fast pulse laser is a very important research direction, and it has very important theoretical significance and application value in investigating the ablation threshold of titanium alloy irradiated by ultra-fast pulse lasers. Irradiated by a picosecond pulse laser with wavelengths of 1064 nm and 532 nm, the surface morphology and feature sizes, including ablation crater width (i.e. diameter, ablation depth, ablation area, ablation volume, single pulse ablation rate, and so forth, of the titanium alloy were studied, and their ablation distributions were obtained. The experimental results show that titanium alloy irradiated by a picosecond pulse infrared laser with a 1064 nm wavelength has better ablation morphology than that of the green picosecond pulse laser with a 532 nm wavelength. The feature sizes are approximately linearly dependent on the laser pulse energy density at low energy density and the monotonic increase in laser pulse energy density. With the increase in energy density, the ablation feature sizes are increased. The rate of increase in the feature sizes slows down gradually once the energy density reaches a certain value, and gradually saturated trends occur at a relatively high energy density. Based on the linear relation between the laser pulse energy density and the crater area of the titanium alloy surface, and the Gaussian distribution of the laser intensity on the cross section, the ablation threshold of titanium alloy irradiated by an ultra-fast pulse laser was calculated to be about 0.109 J/cm2.

  1. MR guided percutaneous laser lumbar disk hernia ablation

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, Takuo; Terao, Tohru; Ishibashi, Toshihiro; Yuhki, Ichiro; Harada, Junta; Tashima, Michiko [Jikei Univ., Chiba (Japan). Kashiwa Hospital; Abe, Toshiaki

    1998-03-01

    An MRI unit for interventional procedure is very useful for minimally invasive surgery of the brain and spine. Percutaneous laser disc decompression (PLDD) utilizing X-ray fluoroscopy is a relatively new less invasive procedure for treatment of lumbar disc herniation. MR guided laser surgery is applied to patients with disc herniation at our department. Approaching the target of the disc protrusion was easily conducted and vaporizing the disc hernia directly using a laser was possible under MR fluoroscopy. The purpose of the present study is to evaluate the usefulness of MR guided percutaneous laser disc hernia ablation (MR-guided PLDHA). As subjects, 36 patients with lumbar disc herniation, including 23 cases with L4/5 involvement and 13 cases with L5/S1 involvement were studied. Among these, 26 were males and 10 were females, age ranging from 24 to 62. We used an open type MR system (Hitachi, Airis 0.3T), a permanent, open configuration MR system. A YAG laser (LaserScope, USA) was used for PLDHA. An MR compatible 18G titanium needle 15 cm in length was used to puncture the herniated discs. The MR compatible needle was clearly visualized, and used to safely and accurately puncture the target herniated disc in each case with multidimensional guidance. Application of the laser was performed with MR guidance. The energy dose from the laser ranged from 800 to 2100 joules. In most cases, signs and symptoms improved in the patients immediately after disc vaporization. The overall success rate was 88.9%. The complication rate was 2.8%, including one case of discitis after PLDHA. MR fluoroscopy sequence permits near real time imaging and provides an easy approach to the therapeutic target of disc herniation. MR guided PLDHA is a minimally invasive procedure and is very useful for the treatment of lumbar disc protrusion. (author)

  2. MR guided percutaneous laser lumbar disk hernia ablation

    International Nuclear Information System (INIS)

    Hashimoto, Takuo; Terao, Tohru; Ishibashi, Toshihiro; Yuhki, Ichiro; Harada, Junta; Tashima, Michiko; Abe, Toshiaki.

    1998-01-01

    An MRI unit for interventional procedure is very useful for minimally invasive surgery of the brain and spine. Percutaneous laser disc decompression (PLDD) utilizing X-ray fluoroscopy is a relatively new less invasive procedure for treatment of lumbar disc herniation. MR guided laser surgery is applied to patients with disc herniation at our department. Approaching the target of the disc protrusion was easily conducted and vaporizing the disc hernia directly using a laser was possible under MR fluoroscopy. The purpose of the present study is to evaluate the usefulness of MR guided percutaneous laser disc hernia ablation (MR-guided PLDHA). As subjects, 36 patients with lumbar disc herniation, including 23 cases with L4/5 involvement and 13 cases with L5/S1 involvement were studied. Among these, 26 were males and 10 were females, age ranging from 24 to 62. We used an open type MR system (Hitachi, Airis 0.3T), a permanent, open configuration MR system. A YAG laser (LaserScope, USA) was used for PLDHA. An MR compatible 18G titanium needle 15 cm in length was used to puncture the herniated discs. The MR compatible needle was clearly visualized, and used to safely and accurately puncture the target herniated disc in each case with multidimensional guidance. Application of the laser was performed with MR guidance. The energy dose from the laser ranged from 800 to 2100 joules. In most cases, signs and symptoms improved in the patients immediately after disc vaporization. The overall success rate was 88.9%. The complication rate was 2.8%, including one case of discitis after PLDHA. MR fluoroscopy sequence permits near real time imaging and provides an easy approach to the therapeutic target of disc herniation. MR guided PLDHA is a minimally invasive procedure and is very useful for the treatment of lumbar disc protrusion. (author)

  3. Endoscopic laser ablation of clival chordoma with magnetic resonance-guided laser induced thermal therapy

    Directory of Open Access Journals (Sweden)

    James Barrese

    2014-12-01

    Conclusion: The endoscopic endonasal approach to MRI-guided laser ablation is both technically feasible and safe. As a result, this therapy may be a useful alternative in hard-to-reach chordomas, or in recurrent cases that have failed other conventional treatment modalities.

  4. Specifications of nanosecond laser ablation with solid targets, aluminum, silicon rubber, and polymethylmethacrylate (PMMA)

    Science.gov (United States)

    Morshedian, Nader

    2017-09-01

    The ablation parameters such as threshold fluence, etch depth, ablation rate and the effect of material targets were investigated under the interaction of laser pulse with low intensity. The parameters of the laser system are: laser pulse energy in the range of 110-140 mJ, wavelength 1064 nm and pulse duration 20 ns. By macroscopic estimation of the outward images of the ablation and data obtained, we can conclude that the photothermal and photoionization processes have more influence for aluminum ablation. In contrast, for polymer samples, from the macroscopic observation of the border pattern at the irradiated spot, and also the data obtained from the experiment results, we deduce that both chemical change due to heating and photochemical dissociation were effective mechanisms of ablation. However, concerning the two polymer samples, apart from considering the same theoretical ablation model, it is conceived that the photomehanical specifications of PMMA are involved in the ablation parameters. The threshold fluence for an ablation rate of 30 laser shots were obtained as 12.4, 24.64, and 11.71 J cm-2, for aluminum, silicon rubber and polymethylmethacrylate (PMMA) respectively. The ablation rate is exponentially decreased by the laser-shot number, especially for aluminum. Furthermore, the etch depth after 30 laser shots was measured as 180, 630 and 870 μm, for aluminum, silicon rubber and PMMA, respectively.

  5. Benign thyroid nodules treatment using percutaneous laser ablation (PLA) and radiofrequency ablation (RFA).

    Science.gov (United States)

    Mauri, Giovanni; Cova, Luca; Monaco, Cristian Giuseppe; Sconfienza, Luca Maria; Corbetta, Sabrina; Benedini, Stefano; Ambrogi, Federico; Milani, Valentina; Baroli, Alberto; Ierace, Tiziana; Solbiati, Luigi

    2016-11-15

    To evaluate the reduction over time of benign thyroid nodules treated using percutaneous laser ablation (PLA) and radiofrequency ablation (RFA) by the same equipe. Ninety patients (age 55.6 ± 14.1 years) underwent ablation for benign thyroid nodule causing compression/aesthetic dissatisfaction from 2011. Fifty-nine (age 55.8 ± 14.1 years) underwent RFA and 31 (age 55.2 ± 14.2 years) PLA, ultrasound guided. Technical success, complications, duration of ablation and treatment, energy deployed, volumetric percentage reduction at 1, 6 and 12 months were derived. A regression model for longitudinal measurements was used with random intercept and random slope. Values are expressed as mean ± standard deviation or N (%). Technical success was always obtained. No major complications occurred. Mean ablation time was 30.1 ± 13.8 vs. 13.9 ± 5.9 min (p < .0001) and mean energy deployment was 5422.3 ± 2484.5 J vs. 34 662.7 ± 15 812.3 J in PLA vs. RFA group. Mean volume reduced from 20.3 ± 16.4 ml to 13.17 ± 10.74 ml (42% ± 17% reduction) at 1st month, 8.7 ± 7.4 ml (60% ± 15% reduction) at 6th month and 7.1 ± 7.7 ml (70%% ± 16% reduction) at 12th month, in PLA group, and from 32.7 ± 19.5 ml to 17.2 ± 12.9 ml (51%±15% reduction) at 1st month, 12.8 ± 9.6 ml (64 ± 14% reduction) at 6th month and 9.9 ± 9.2 ml (74% ± 14% reduction) at 12th month in RFA group. No difference in time course of the relative volume reduction between the two techniques was found. RFA and PLA are similarly feasible, safe and effective in treating benign thyroid nodules when performed by the same equipe. RFA is faster than PLA but require significantly higher energy.

  6. Three dimensional characterization of laser ablation craters using high resolution X-ray computed tomography

    Science.gov (United States)

    Galmed, A. H.; du Plessis, A.; le Roux, S. G.; Hartnick, E.; Von Bergmann, H.; Maaza, M.

    2018-01-01

    Laboratory X-ray computed tomography is an emerging technology for the 3D characterization and dimensional analysis of many types of materials. In this work we demonstrate the usefulness of this characterization method for the full three dimensional analysis of laser ablation craters, in the context of a laser induced breakdown spectroscopy setup. Laser induced breakdown spectroscopy relies on laser ablation for sampling the material of interest. We demonstrate here qualitatively (in images) and quantitatively (in terms of crater cone angles, depths, diameters and volume) laser ablation crater analysis in 3D for metal (aluminum) and rock (false gold ore). We show the effect of a Gaussian beam profile on the resulting crater geometry, as well as the first visual evidence of undercutting in the rock sample, most likely due to ejection of relatively large grains. The method holds promise for optimization of laser ablation setups especially for laser induced breakdown spectroscopy.

  7. Noncontact Er:YAG laser ablation: clinical evaluation.

    Science.gov (United States)

    Dostálová, T; Jelínková, H; Kucerová, H; Krejsa, O; Hamal, K; Kubelka, J; Procházka, S

    1998-10-01

    The aim of this study is to evaluate the quality of laser ablation in comparison with the classical drilling preparation. For the experiment, the Er:YAG laser drilling machine was used. The system had a laser head, water cooler, and power supply with automatic control. Spot size of 300-350 microns was used for the preparation. Repetition rate of 1-4 Hz, and pulse energies of 100-400 mJ with water spray were chosen. Cavity shape in comparison with classical drill, time of preparation, and influence of cavity shape on filling materials retention in accordance with the U.S. Public Health Service System were used. The evaluation criteria for noncontact Er:YAG ablation were done. The cavity shape is irregular, but spot surface has larger area and microretentive appearance. Caries of enamel and dentin were treated with a noncontact preparation. It was possible to remove the old insufficient fillings, except for amalgam or metal alloys. The average number of pulses was 111.22 (SE 67.57). Vibrations of microexplosions during preparation were felt by patients on 14 cavities; however, nobody felt unpleasant pain. The qualities of filling materials in laser cavities were very stable; however, cavo surface margin discoloration of 82-86% of Alfa rating could be a problem. Changes of the color and anatomic form of the tooth were observed in 4-8%. In comparison with the classical treatment, it could be said that the retention and quality of filling materials is the same or very similar.

  8. Photonic Doppler velocimetry of laser-ablated ultrathin metals.

    Science.gov (United States)

    Valenzuela, A R; Rodriguez, G; Clarke, S A; Thomas, K A

    2007-01-01

    Obtaining velocity information from the interaction of a laser pulse on a metal layer provides insight into the rapid dynamics of material removal and plasma plume physics during ablation. A traditional approach involves using a velocity interferometer system for any reflector (VISAR) on a reflective metal surface. However, when the target is a thin metal layer, the cohesion of the surface is quickly lost resulting in a large spread of particle velocities that cannot be easily resolved by VISAR. This is due to material ejection"confusing" the VISAR measurement surface, effectively washing out the spatial fringe visibility in the VISAR interferometer. A new heterodyne-based optical velocimeter method is the photonic Doppler velocimeter (PDV). Because PDV tracks motion in a frequency encoded temporal electro-optical signal, velocity information is preserved and allows for multiple velocity components to be recorded simultaneously. The challenge lies in extracting PDV velocity information at short (nanosecond) laser ablation time scales with rapidly varying heterodyne beats by using electronic, optical, and analytical techniques to recover the velocity information from a fleeting signal. Here we show how we have been able to obtain velocity information on the nanosecond time scale and are able to compare it to hydrodynamic simulations. Also, we examine refinements to our PDV system by increasing the bandwidth, utilizing different probes, and sampling different analysis techniques.

  9. Equation of state study of Laser Megajoule capsules ablator materials

    International Nuclear Information System (INIS)

    Colin-Lalu, Pierre

    2016-01-01

    This PhD thesis enters the field of inertial confinement fusion studies. In particular, it focuses on the equation of state tables of ablator materials synthesized on LMJ capsules. This work is indeed aims at improving the theoretical models introduced into the equation of state tables. We focused in the Mbar-eV pressure-temperature range because it can be access on kJ-scale laser facilities.In order to achieve this, we used the QEOS model, which is simple to use, configurable, and easily modifiable.First, quantum molecular dynamics (QMD) simulations were performed to generate cold compression curve as well as shock compression curves along the principal Hugoniot. Simulations were compared to QEOS model and showed that atomic bond dissociation has an effect on the compressibility. Results from these simulations are then used to parametrize the Grueneisen parameter in order to generate a tabulated equation of state that includes dissociation. It allowed us to show its influence on shock timing in a hydrodynamic simulation.Second, thermodynamic states along the Hugoniot were measured during three experimental campaigns upon the LULI2000 and GEKKO XII laser facilities. Experimental data confirm QMD simulations.This study was performed on two ablator materials which are an undoped polymer CHO, and a silicon-doped polymer CHOSi. Results showed universal shock compression properties. (author) [fr

  10. Hard tissue ablation with a spray-assisted mid-IR laser

    International Nuclear Information System (INIS)

    Kang, H W; Rizoiu, I; Welch, A J

    2007-01-01

    The objective of this study was to understand the dominant mechanism(s) for dental enamel ablation with the application of water spray. A free-running Er,Cr:YSGG (yttrium, scandium, gallium, garnet) laser was used to ablate human enamel tissue at various radiant exposures. During dental ablation, distilled water was sprayed on the sample surface, and these results were compared to ablation without a spray (dry ablation). In order to identify dominant ablation mechanisms, transient acoustic waves were compared to ablation thresholds and the volume of material removed. The ablation profile and depth were measured using optical coherence tomography (OCT). Irregular surface modification, charring and peripheral cracks were associated with dry ablation, whereas craters for spray samples were relatively clean without thermal damage. In spite of a 60% higher ablation threshold for spray associated irradiations owing to water absorption, acoustic peak pressures were six times higher and ablation volume was up to a factor of 2 larger compared to dry ablation. The enhanced pressure and ablation performance of the spray-assisted process was the result of rapid water vaporization, material ejection with recoil stress, interstitial water explosion and possibly liquid-jet formation. With water cooling and abrasive/disruptive mechanical effects, the spray ablation can be a safe and efficient modality for dental treatment

  11. Laser Ablation Increases PEM/Catalyst Interfacial Area

    Science.gov (United States)

    Whitacre, Jay; Yalisove, Steve

    2009-01-01

    An investigational method of improving the performance of a fuel cell that contains a polymer-electrolyte membrane (PEM) is based on the concept of roughening the surface of the PEM, prior to deposition of a thin layer of catalyst, in order to increase the PEM/catalyst interfacial area and thereby increase the degree of utilization of the catalyst. The roughening is done by means of laser ablation under carefully controlled conditions. Next, the roughened membrane surface is coated with the thin layer of catalyst (which is typically platinum), then sandwiched between two electrode/catalyst structures to form a membrane/ele c t - rode assembly. The feasibility of the roughening technique was demonstrated in experiments in which proton-conducting membranes made of a perfluorosulfonic acid-based hydrophilic, protonconducting polymer were ablated by use of femtosecond laser pulses. It was found that when proper combinations of the pulse intensity, pulse-repetition rate, and number of repetitions was chosen, the initially flat, smooth membrane surfaces became roughened to such an extent as to be converted to networks of nodules interconnected by filaments (see Figure 1). In further experiments, electrochemical impedance spectroscopy (EIS) was performed on a pristine (smooth) membrane and on two laser-roughened membranes after the membranes were coated with platinum on both sides. Some preliminary EIS data were interpreted as showing that notwithstanding the potential for laser-induced damage, the bulk conductivities of the membranes were not diminished in the roughening process. Other preliminary EIS data (see Figure 2) were interpreted as signifying that the surface areas of the laser-roughened membranes were significantly greater than those of the smooth membrane. Moreover, elemental analyses showed that the sulfur-containing molecular groups necessary for proton conduction remained intact, even near the laser-roughened surfaces. These preliminary results can be taken

  12. Assessment of in vivo laser ablation using MR elastography with an inertial driver.

    Science.gov (United States)

    Chen, Jun; Woodrum, David A; Glaser, Kevin J; Murphy, Matthew C; Gorny, Krzysztof; Ehman, Richard

    2014-07-01

    To evaluate the feasibility of using MR Elastography (MRE) to monitor tissue coagulation extent during in vivo percutaneous laser ablation of the liver. A novel inertial acoustic driver was developed to apply mechanical waves via the ablation instrument. Ablation testing was performed in live juvenile female pigs under anesthesia in a 1.5-T whole-body MRI scanner. The inertial driver produced suitable mechanical wave fields in the liver before, during, and after the laser ablation. During 2-min ablations using 4.5-, 7.5- and 15-W laser power, the stiffness of the lesions changed substantially in response to laser heating, indicative of protein denaturation. After a lethal thermal dose (2-min, 15-W) ablation, lesion stiffness was significantly greater than the baseline values (P W) ablations (64.4% vs. 22.5%, P = 0.009). MRE was shown capable of measuring tissue stiffness changes due to in vivo laser ablation. If confirmed through additional studies, this technology may be useful in clinical tumor ablation to monitor the spatial extent of tissue coagulation. Copyright © 2013 Wiley Periodicals, Inc.

  13. Morphological and spectroscopic characterization of laser-ablated tungsten at various laser irradiances

    Energy Technology Data Exchange (ETDEWEB)

    Akram, Mahreen; Bashir, Shazia; Hayat, Asma; Mahmood, Khaliq; Dawood, Asadullah [Government College University, Centre for Advanced Studies in Physics, Lahore (Pakistan); Rafique, Muhammad Shahid [University of Engineering and Technology, Department of Physics, Lahore (Pakistan); Bashir, M.F. [COMSATS Institute of Information Technology, Department of Physics, Lahore (Pakistan)

    2015-06-15

    The variation in surface morphology and plasma parameters of laser irradiated tungsten has been investigated as a function of irradiance. For this purpose, Nd:YAG laser (1064 nm, 10 ns, 10 Hz) is employed. Tungsten targets were exposed to various laser irradiances ranging from 6 to 50 GW/cm{sup 2} under ambient environment of argon at a pressure of 20 Torr. Scanning electron microscope analysis has been performed to analyze the surface modification of irradiated tungsten. It revealed the formation of micro- and nanoscale surface structures. In central ablated area, distinct grains and crack formation are observed, whereas peripheral ablated areas are dominated by cones and pinhole formation. It was observed that at irradiances exceeding a value of 13 GW/cm{sup 2}, the morphological trend of the observed structures has been changed from erosion to melting and re-deposition dominant phase. Ablation efficiency as a function of laser irradiance has also been investigated by measuring the crater depth using surface profilometry analysis. It is found to be maximum at an irradiance of 13 GW/cm{sup 2} and decreases at high laser irradiances. In order to correlate the accumulated effects of plasma parameters with the surface modification, laser-induced breakdown spectroscopy analysis has been performed. The electron temperature and number density of tungsten plasma have been evaluated at various laser irradiances. Initially with the increase of the laser irradiance up to 13 GW/cm{sup 2}, an increasing trend is observed for both plasma parameters due to enhanced energy deposition. Afterward, a decreasing trend is achieved which is attributed to the shielding effect. With further increase in irradiance, a saturation stage comes and insignificant changes are observed in plasma parameters. This saturation is explainable on the basis of the formation of a self-regulating regime near the target surface. Surface modifications of laser irradiated tungsten have been correlated with

  14. Thermal effect of laser ablation on the surface of carbon fiber reinforced plastic during laser processing

    Science.gov (United States)

    Ohkubo, Tomomasa; Sato, Yuji; Matsunaga, Ei-ichi; Tsukamoto, Masahiro

    2018-02-01

    Although laser processing is widely used for many applications, the cutting quality of carbon fiber reinforced plastic (CFRP) decreases around the heat-affected zone (HAZ) during laser processing. Carbon fibers are exposed around the HAZ, and tensile strength decreases with increasing length of the HAZ. Some theoretical studies of thermal conductions that do not consider fluid dynamics have been performed; however, theoretical considerations that include the dynamics of laser ablation are scarce. Using removed mass and depth observed from experiments, the dynamics of laser ablation of CFRP with high-temperature and high-pressure of compressive gas is simulated herein. In this calculation, the mushroom-like shape of laser ablation is qualitatively simulated compared with experiments using a high-speed camera. Considering the removal temperature of the resin and the temperature distribution at each point on the surface, the simulation results suggest that a wide area of the resin is removed when the processing depth is shallow, and a rounded kerf is generated as the processing depth increases.

  15. Laser ablation of dental materials using a microsecond Nd:YAG laser

    Science.gov (United States)

    Siniaeva, M. L.; Siniavsky, M. N.; Pashinin, V. P.; Mamedov, Ad. A.; Konov, V. I.; Kononenko, V. V.

    2009-05-01

    The action of microsecond laser pulses with a wavelength of 1064 nm on dental tissues (enamel and dentin) and various dental materials used for tooth replacement and filling (ceramics, metal alloys, and composites) is studied. It is demonstrated that the ablation thresholds of all of the dental materials are significantly lower than the threshold laser fluences for the dental tissue ( E thr = 200-300 J/cm2). At the laser fluences that do not allow ablation and damage of the dental tissues, the dental materials are effectively removed at a rate of no greater than 40 μm per pulse. It is shown that the laser ablation of the materials under study involves two processes (evaporation and volume explosion) depending on the optical density. The results obtained indicate that the laser radiation with a wavelength of 1064 nm and the microsecond pulse duration is promising for dental applications, since it allows effective cleaning of the tooth surface from various dental materials in the absence of the damages of dental tissues.

  16. Mid-IR enhanced laser ablation molecular isotopic spectrometry

    Science.gov (United States)

    Brown, Staci; Ford, Alan; Akpovo, Codjo A.; Johnson, Lewis

    2016-08-01

    A double-pulsed laser-induced breakdown spectroscopy (DP-LIBS) technique utilizing wavelengths in the mid-infrared (MIR) for the second pulse, referred to as double-pulse LAMIS (DP-LAMIS), was examined for its effect on detection limits compared to single-pulse laser ablation molecular isotopic spectrometry (LAMIS). A MIR carbon dioxide (CO2) laser pulse at 10.6 μm was employed to enhance spectral emissions from nanosecond-laser-induced plasma via mid-IR reheating and in turn, improve the determination of the relative abundance of isotopes in a sample. This technique was demonstrated on a collection of 10BO and 11BO molecular spectra created from enriched boric acid (H3BO3) isotopologues in varying concentrations. Effects on the overall ability of both LAMIS and DP-LAMIS to detect the relative abundance of boron isotopes in a starting sample were considered. Least-squares fitting to theoretical models was used to deduce plasma parameters and understand reproducibility of results. Furthermore, some optimization for conditions of the enhanced emission was achieved, along with a comparison of the overall emission intensity, plasma density, and plasma temperature generated by the two techniques.

  17. Data Fitting to Study Ablated Hard Dental Tissues by Nanosecond Laser Irradiation.

    Directory of Open Access Journals (Sweden)

    Y Al-Hadeethi

    Full Text Available Laser ablation of dental hard tissues is one of the most important laser applications in dentistry. Many works have reported the interaction of laser radiations with tooth material to optimize laser parameters such as wavelength, energy density, etc. This work has focused on determining the relationship between energy density and ablation thresholds using pulsed, 5 nanosecond, neodymium-doped yttrium aluminum garnet; Nd:Y3Al5O12 (Nd:YAG laser at 1064 nanometer. For enamel and dentin tissues, the ablations have been performed using laser-induced breakdown spectroscopy (LIBS technique. The ablation thresholds and relationship between energy densities and peak areas of calcium lines, which appeared in LIBS, were determined using data fitting. Furthermore, the morphological changes were studied using Scanning Electron Microscope (SEM. Moreover, the chemical stability of the tooth material after ablation has been studied using Energy-Dispersive X-Ray Spectroscopy (EDX. The differences between carbon atomic % of non-irradiated and irradiated samples were tested using statistical t-test. Results revealed that the best fitting between energy densities and peak areas of calcium lines were exponential and linear for enamel and dentin, respectively. In addition, the ablation threshold of Nd:YAG lasers in enamel was higher than that of dentin. The morphology of the surrounded ablated region of enamel showed thermal damages. For enamel, the EDX quantitative analysis showed that the atomic % of carbon increased significantly when laser energy density increased.

  18. Data Fitting to Study Ablated Hard Dental Tissues by Nanosecond Laser Irradiation.

    Science.gov (United States)

    Al-Hadeethi, Y; Al-Jedani, S; Razvi, M A N; Saeed, A; Abdel-Daiem, A M; Ansari, M Shahnawaze; Babkair, Saeed S; Salah, Numan A; Al-Mujtaba, A

    2016-01-01

    Laser ablation of dental hard tissues is one of the most important laser applications in dentistry. Many works have reported the interaction of laser radiations with tooth material to optimize laser parameters such as wavelength, energy density, etc. This work has focused on determining the relationship between energy density and ablation thresholds using pulsed, 5 nanosecond, neodymium-doped yttrium aluminum garnet; Nd:Y3Al5O12 (Nd:YAG) laser at 1064 nanometer. For enamel and dentin tissues, the ablations have been performed using laser-induced breakdown spectroscopy (LIBS) technique. The ablation thresholds and relationship between energy densities and peak areas of calcium lines, which appeared in LIBS, were determined using data fitting. Furthermore, the morphological changes were studied using Scanning Electron Microscope (SEM). Moreover, the chemical stability of the tooth material after ablation has been studied using Energy-Dispersive X-Ray Spectroscopy (EDX). The differences between carbon atomic % of non-irradiated and irradiated samples were tested using statistical t-test. Results revealed that the best fitting between energy densities and peak areas of calcium lines were exponential and linear for enamel and dentin, respectively. In addition, the ablation threshold of Nd:YAG lasers in enamel was higher than that of dentin. The morphology of the surrounded ablated region of enamel showed thermal damages. For enamel, the EDX quantitative analysis showed that the atomic % of carbon increased significantly when laser energy density increased.

  19. A Status Report of the X-50LR Program. A Laser Propulsion Program

    National Research Council Canada - National Science Library

    Mead, Frank

    2001-01-01

    ... a period of 5 years in order to demonstrate the concept and its attractive features. The concept was to be a nanosatellite in which the laser propulsion engine and satellite hardware were intimately shared...

  20. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Laser ablation plume dynamics in nanoparticle synthesis

    Science.gov (United States)

    Osipov, V. V.; Platonov, V. V.; Lisenkov, V. V.

    2009-06-01

    The dynamics of the plume ejected from the surface of solid targets (YSZ, Nd:YAG and graphite) by a CO2 laser pulse with a duration of ~500 μs (at the 0.03 level), energy of 1.0-1.3 J and peak power of 6-7 kW have been studied using high-speed photography of the plume luminescence and shadow. The targets were used to produce nanopowders by laser evaporation. About 200 μs after termination of the pulse, shadowgraph images of the plumes above the YSZ and Nd:YAG targets showed dark straight tracks produced by large particles. The formation of large (~10 μm) particles is tentatively attributed to cracking of the solidified melt at the bottom of the ablation crater. This is supported by the fact that no large particles are ejected from graphite, which sublimes without melting. Further support to this hypothesis is provided by numerical 3D modelling of melt cooling in craters produced by laser pulses of different shapes.

  1. Modification of polyimide wetting properties by laser ablated conical microstructures

    International Nuclear Information System (INIS)

    Least, Brandon T.; Willis, David A.

    2013-01-01

    Laser texturing of Kapton ® HN polyimide was performed by low-fluence ablation using a pulsed, frequency tripled (349 nm) Nd:YLF laser. The laser was scanned in two dimensions in order to generate texture over a large area. The laser overlap percentage and fluence were varied and the resulting texture was studied. The texture features were inspected by electron microscopy and energy dispersive X-Ray spectroscopy (EDS), while the static contact angle of de-ionized water was measured by a contact angle goniometer. Rounded bump features were formed at all fluences, which decreased in areal density with fluence and number of laser pulses. Conical microstructures or “cones” were also formed at most fluences. Cones were larger than the bumps and thus had lower areal density, which increased as a function of the number of laser pulses. The polyimide was hydrophilic before texturing, with a contact angle of approximately 76°. For most of the experimental conditions the contact angle increased as a result of texturing, with the contact angle exceeding 90° for some textured surfaces, and reaching values as high as 118°. In general, the surfaces with significant increases in contact angle had high density of texture features, either bumps or cones. The surfaces that experienced a decrease in contact angle generally had low density of texture features. The increase in contact angle from a wetting (θ 90°) cannot be explained by texturing alone. EDS measurements indicate that textured regions had higher carbon content than the untextured regions due to depletion of oxygen species. The increase in carbon content relative to the oxygen content increased the native contact angle of the surface, causing the transition from hydrophilic to hydrophobic behavior. The contact angle of a textured surface increased as the relative spacing of features (diameter to spacing) decreased.

  2. An investigation on 800 nm femtosecond laser ablation of K9 glass in air and vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Shi-zhen, E-mail: xusz@uestc.edu.cn [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Yao, Cai-zhen [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Dou, Hong-qiang [Department of Material Science and Engineering, Sichuan Engineering Technical College, Deyang 618000 (China); Liao, Wei, E-mail: liaowei@caep.cn [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Li, Xiao-yang; Ding, Ren-jie [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Zhang, Li-juan; Liu, Hao; Yuan, Xiao-dong [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Zu, Xiao-tao [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2017-06-01

    Highlights: • The fs laser ablation of borosilicate glass (K9) were investigated under 35 and 500 fs pulses. • At high fluence regime, the ablation rate at 35 fs in air increased to a plateau, and 500 fs in air and vacuum decreased. • The mechanisms of multiple-photon ionization and impact ionization were included. • The ablation morphologies of smooth zone and laser-induced periodic surface structures were presented and illustrated. • The ablation mechanisms of non-thermal and thermal ablation were included. - Abstract: Ablation rates of K9 glass were studied as a function of femtosecond laser fluences. The central wavelength was 800 nm, and pulse durations of 35 fs and 500 fs in air and vacuum were employed. Ablation thresholds of 0.42 J/cm{sup 2} and 2.1 J/cm{sup 2} were obtained at 35 fs and 500 fs, respectively, which were independent with the ambient conditions and depend on the incident pulse numbers due to incubation effects. The ablation rate of 35 fs pulse laser increased with the increasing of laser fluence in vacuum, while in air condition, it slowly increased to a plateau at high fluence. The ablation rate of 500 fs pulse laser showed an increase at low fluence and a slow drop of ablation rate was observed at high fluence in air and vacuum, which may due to the strong defocusing effects associated with the non-equilibrium ionization of air, and/or the shielding effects of conduction band electrons (CBEs) produced by multi-photon ionization and impact ionization in K9 glass surface. The typical ablation morphologies, e.g. smooth zone and laser-induced periodic surface structures (LIPSS) were also presented and illustrated.

  3. Theoretical and experimental analysis of the impact on ablation depth of microchannel milling using femtosecond laser

    Science.gov (United States)

    Lei, Chen; Pan, Zhang; Jianxiong, Chen; Tu, Yiliu

    2018-04-01

    The plasma brightness cannot be used as a direct indicator of ablation depth detection by femtosecond laser was experimentally demonstrated, which led to the difficulty of depth measurement in the maching process. The tests of microchannel milling on the silicon wafer were carried out in the micromachining center in order to obtain the influences of parameters on the ablation depth. The test results showed that the defocusing distance had no significant impact on ablation depth in LAV effective range. Meanwhile, the reason of this was explained in this paper based on the theoretical analysis and simulation calculation. Then it was proven that the ablation depth mainly depends on laser fluence, step distance and scanning velocity. Finally, a research was further carried out to study the laser parameters which relate with the microchannel ablation depth inside the quartz glass for more efficiency and less cost in processing by femtosecond laser.

  4. Non-ablative fractional laser provides long-term improvement of mature burn scars

    DEFF Research Database (Denmark)

    Taudorf, Elisabeth H; Danielsen, Patricia L; Paulsen, Ida F

    2015-01-01

    BACKGROUND AND OBJECTIVES: Non-ablative fractional laser-treatment is evolving for burn scars. The objective of this study was to evaluate clinical and histological long-term outcome of 1,540 nm fractional Erbium: Glass laser, targeting superficial, and deep components of mature burn scars...... of scar-appearance. CONCLUSIONS: Combined superficial and deep non-ablative fractional laser-treatments induce long-term clinical and histological improvement of mature burn scars....

  5. Frontiers in propulsion research: Laser, matter-antimatter, excited helium, energy exchange thermonuclear fusion

    Science.gov (United States)

    Papailiou, D. D. (Editor)

    1975-01-01

    Concepts are described that presently appear to have the potential for propulsion applications in the post-1990 era of space technology. The studies are still in progress, and only the current status of investigation is presented. The topics for possible propulsion application are lasers, nuclear fusion, matter-antimatter annihilation, electronically excited helium, energy exchange through the interaction of various fields, laser propagation, and thermonuclear fusion technology.

  6. Laser-Powered Thrusters for High Efficiency Variable Specific Impulse Missions (Preprint)

    National Research Council Canada - National Science Library

    Phipps, Claude R; Luke, J. R; Helgeson, W. D

    2007-01-01

    .... Considering a laser ablation propulsion device as an electric thruster, use of energetic ablation fuels can give thrust electrical efficiency greater than unity at the bottom of this Isp range...

  7. Measurements of erbium laser-ablation efficiency in hard dental tissues under different water cooling conditions.

    Science.gov (United States)

    Kuščer, Lovro; Diaci, Janez

    2013-10-01

    Laser triangulation measurements of Er:YAG and Er,Cr:YSGG laser-ablated volumes in hard dental tissues are made, in order to verify the possible existence of a "hydrokinetic" effect that has been proposed as an alternative to the "subsurface water expansion" mechanism for hard-tissue laser ablation. No evidence of the hydrokinetic effect could be observed under a broad range of tested laser parameters and water cooling conditions. On the contrary, the application of water spray during laser exposure of hard dental material is observed to diminish the laser-ablation efficiency (AE) in comparison with laser exposure under the absence of water spray. Our findings are in agreement with the generally accepted principle of action for erbium laser ablation, which is based on fast subsurface expansion of laser-heated water trapped within the interstitial structure of hard dental tissues. Our measurements also show that the well-known phenomenon of ablation stalling, during a series of consecutive laser pulses, can primarily be attributed to the blocking of laser light by the loosely bound and recondensed desiccated minerals that collect on the tooth surface during and following laser ablation. In addition to the prevention of tooth bulk temperature buildup, a positive function of the water spray that is typically used with erbium dental lasers is to rehydrate these minerals, and thus sustaining the subsurface expansion ablation process. A negative side effect of using a continuous water spray is that the AE gets reduced due to the laser light being partially absorbed in the water-spray particles above the tooth and in the collected water pool on the tooth surface. Finally, no evidence of the influence of the water absorption shift on the hypothesized increase in the AE of the Er,Cr:YSGG wavelength is observed.

  8. Physical mechanisms of SiN{sub x} layer structuring with ultrafast lasers by direct and confined laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, S., E-mail: rapp@hm.edu [Faculty of Applied Sciences and Mechatronics, Munich University of Applied Sciences, Lothstraße 34, 80335 Munich (Germany); Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Paul-Gordan-Straße 6, 91052 Erlangen (Germany); Heinrich, G. [Technische Universität Ilmenau, Institut für Physik, Weimarer Straße 25., 98693 Ilmenau (Germany); CiS Forschungsinstitut für Mikrosensorik und Photovoltaik GmbH, Konrad-Zuse-Straße 14, 99099 Erfurt (Germany); Wollgarten, M. [Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Huber, H. P. [Faculty of Applied Sciences and Mechatronics, Munich University of Applied Sciences, Lothstraße 34, 80335 Munich (Germany); Schmidt, M. [Friedrich-Alexander-Universität Erlangen-Nürnberg, Lehrstuhl für Photonische Technologien, Konrad-Zuse-Straße 3-5, 91052 Erlangen (Germany)

    2015-03-14

    In the production process of silicon microelectronic devices and high efficiency silicon solar cells, local contact openings in thin dielectric layers are required. Instead of photolithography, these openings can be selectively structured with ultra-short laser pulses by confined laser ablation in a fast and efficient lift off production step. Thereby, the ultrafast laser pulse is transmitted by the dielectric layer and absorbed at the substrate surface leading to a selective layer removal in the nanosecond time domain. Thermal damage in the substrate due to absorption is an unwanted side effect. The aim of this work is to obtain a deeper understanding of the physical laser-material interaction with the goal of finding a damage-free ablation mechanism. For this, thin silicon nitride (SiN{sub x}) layers on planar silicon (Si) wafers are processed with infrared fs-laser pulses. Two ablation types can be distinguished: The known confined ablation at fluences below 300 mJ/cm{sup 2} and a combined partial confined and partial direct ablation at higher fluences. The partial direct ablation process is caused by nonlinear absorption in the SiN{sub x} layer in the center of the applied Gaussian shaped laser pulses. Pump-probe investigations of the central area show ultra-fast reflectivity changes typical for direct laser ablation. Transmission electron microscopy results demonstrate that the Si surface under the remaining SiN{sub x} island is not damaged by the laser ablation process. At optimized process parameters, the method of direct laser ablation could be a good candidate for damage-free selective structuring of dielectric layers on absorbing substrates.

  9. Physical mechanisms of SiNx layer structuring with ultrafast lasers by direct and confined laser ablation

    International Nuclear Information System (INIS)

    Rapp, S.; Heinrich, G.; Wollgarten, M.; Huber, H. P.; Schmidt, M.

    2015-01-01

    In the production process of silicon microelectronic devices and high efficiency silicon solar cells, local contact openings in thin dielectric layers are required. Instead of photolithography, these openings can be selectively structured with ultra-short laser pulses by confined laser ablation in a fast and efficient lift off production step. Thereby, the ultrafast laser pulse is transmitted by the dielectric layer and absorbed at the substrate surface leading to a selective layer removal in the nanosecond time domain. Thermal damage in the substrate due to absorption is an unwanted side effect. The aim of this work is to obtain a deeper understanding of the physical laser-material interaction with the goal of finding a damage-free ablation mechanism. For this, thin silicon nitride (SiN x ) layers on planar silicon (Si) wafers are processed with infrared fs-laser pulses. Two ablation types can be distinguished: The known confined ablation at fluences below 300 mJ/cm 2 and a combined partial confined and partial direct ablation at higher fluences. The partial direct ablation process is caused by nonlinear absorption in the SiN x layer in the center of the applied Gaussian shaped laser pulses. Pump-probe investigations of the central area show ultra-fast reflectivity changes typical for direct laser ablation. Transmission electron microscopy results demonstrate that the Si surface under the remaining SiN x island is not damaged by the laser ablation process. At optimized process parameters, the method of direct laser ablation could be a good candidate for damage-free selective structuring of dielectric layers on absorbing substrates

  10. Precise ablation of dental hard tissues with ultra-short pulsed lasers. Preliminary exploratory investigation on adequate laser parameters.

    Science.gov (United States)

    Bello-Silva, Marina Stella; Wehner, Martin; Eduardo, Carlos de Paula; Lampert, Friedrich; Poprawe, Reinhart; Hermans, Martin; Esteves-Oliveira, Marcella

    2013-01-01

    This study aimed to evaluate the possibility of introducing ultra-short pulsed lasers (USPL) in restorative dentistry by maintaining the well-known benefits of lasers for caries removal, but also overcoming disadvantages, such as thermal damage of irradiated substrate. USPL ablation of dental hard tissues was investigated in two phases. Phase 1--different wavelengths (355, 532, 1,045, and 1,064 nm), pulse durations (picoseconds and femtoseconds) and irradiation parameters (scanning speed, output power, and pulse repetition rate) were assessed for enamel and dentin. Ablation rate was determined, and the temperature increase measured in real time. Phase 2--the most favorable laser parameters were evaluated to correlate temperature increase to ablation rate and ablation efficiency. The influence of cooling methods (air, air-water spray) on ablation process was further analyzed. All parameters tested provided precise and selective tissue ablation. For all lasers, faster scanning speeds resulted in better interaction and reduced temperature increase. The most adequate results were observed for the 1064-nm ps-laser and the 1045-nm fs-laser. Forced cooling caused moderate changes in temperature increase, but reduced ablation, being considered unnecessary during irradiation with USPL. For dentin, the correlation between temperature increase and ablation efficiency was satisfactory for both pulse durations, while for enamel, the best correlation was observed for fs-laser, independently of the power used. USPL may be suitable for cavity preparation in dentin and enamel, since effective ablation and low temperature increase were observed. If adequate laser parameters are selected, this technique seems to be promising for promoting the laser-assisted, minimally invasive approach.

  11. Double pulse laser ablation and plasma: Laser induced breakdown spectroscopy signal enhancement

    International Nuclear Information System (INIS)

    Babushok, V.I.; DeLucia, F.C.; Gottfried, J.L.; Munson, C.A.; Miziolek, A.W.

    2006-01-01

    A review of recent results of the studies of double laser pulse plasma and ablation for laser induced breakdown spectroscopy applications is presented. The double pulse laser induced breakdown spectroscopy configuration was suggested with the aim of overcoming the sensitivity shortcomings of the conventional single pulse laser induced breakdown spectroscopy technique. Several configurations have been suggested for the realization of the double pulse laser induced breakdown spectroscopy technique: collinear, orthogonal pre-spark, orthogonal pre-heating and dual pulse crossed beam modes. In addition, combinations of laser pulses with different wavelengths, different energies and durations were studied, thus providing flexibility in the choice of wavelength, pulse width, energy and pulse sequence. The double pulse laser induced breakdown spectroscopy approach provides a significant enhancement in the intensity of laser induced breakdown spectroscopy emission lines up to two orders of magnitude greater than a conventional single pulse laser induced breakdown spectroscopy. The double pulse technique leads to a better coupling of the laser beam with the plasma plume and target material, thus providing a more temporally effective energy delivery to the plasma and target. The experimental results demonstrate that the maximum effect is obtained at some optimum separation delay time between pulses. The optimum value of the interpulse delay depends on several factors, such as the target material, the energy level of excited states responsible for the emission, and the type of enhancement process considered. Depending on the specified parameter, the enhancement effects were observed on different time scales ranging from the picosecond time level (e.g., ion yield, ablation mass) up to the hundred microsecond level (e.g., increased emission intensity for laser induced breakdown spectroscopy of submerged metal target in water). Several suggestions have been proposed to explain

  12. Water content contribution in calculus phantom ablation during Q-switched Tm:YAG laser lithotripsy.

    Science.gov (United States)

    Zhang, Jian J; Rajabhandharaks, Danop; Xuan, Jason Rongwei; Wang, Hui; Chia, Ray W J; Hasenberg, Tom; Kang, Hyun Wook

    2015-01-01

    Q-switched (QS) Tm:YAG laser ablation mechanisms on urinary calculi are still unclear to researchers. Here, dependence of water content in calculus phantom on calculus ablation performance was investigated. White gypsum cement was used as a calculus phantom model. The calculus phantoms were ablated by a total 3-J laser pulse exposure (20 mJ, 100 Hz, 1.5 s) and contact mode with N=15 sample size. Ablation volume was obtained on average 0.079, 0.122, and 0.391  mm3 in dry calculus in air, wet calculus in air, and wet calculus in-water groups, respectively. There were three proposed ablation mechanisms that could explain the effect of water content in calculus phantom on calculus ablation performance, including shock wave due to laser pulse injection and bubble collapse, spallation, and microexplosion. Increased absorption coefficient of wet calculus can cause stronger spallation process compared with that caused by dry calculus; as a result, higher calculus ablation was observed in both wet calculus in air and wet calculus in water. The test result also indicates that the shock waves generated by short laser pulse under the in-water condition have great impact on the ablation volume by Tm:YAG QS laser.

  13. Evaluation of ablation efficiency and surface morphology of human teeth upon irradiation with femtosecond laser pulses

    Science.gov (United States)

    Shaheen, M. E.; Gagnon, J. E.; Fryer, B. J.

    2014-11-01

    This study investigates changes in ablation efficiency and surface morphology induced in human dental enamel and dentin upon interaction with femtosecond laser pulses at variable energies and number of laser pulses. Craters were created using a Ti:sapphire femtosecond laser ablation system operating at a wavelength of 785 nm, pulse width of 130 fs, and repetition rate of 20 Hz. Various techniques, such as optical and scanning electron microscopy and inductively coupled plasma mass spectrometry (ICP-MS), were used to evaluate ablation depth, amount of material ablated, and surface morphology of the craters. Ablation rate (ablation depth per pulse) was found to be lower in enamel than dentin with the maximum rate occurring at fluence of 12.4 J cm-2 in both materials. A drop in ablation rate was observed for fluence greater than 12.4 J cm-2 and was attributed to attenuation of laser energy due to interaction with the laser-generated particles. Above this fluence, signs of thermal effects, such as melting and formation of droplets of molten material at the sample surface, were observed. The response of the ICP-MS indicated that the amount of ablated material removed from dentin is greater than that removed from enamel by a factor of 1.5 or more at all investigated fluence.

  14. Study on the lithium compound clusters using laser ablation

    International Nuclear Information System (INIS)

    Yokoyama, Keiichi

    2001-01-01

    Lithium-rich nonstoichiometric binary clusters including hyperlithiated molecules were found to be produced by a nanosecond laser ablation of lithium metal or compound target. Structural information on Li 3 O was obtained for the first time from experiments by measuring and analyzing photoionization efficiency curves of mass-selected ions. For example, the structure of Li 3 O was concluded to have both D 3h and C 2v symmetry. In other words, the vibrational wavefunction even at the ground state spreads over the C 2v and D 3h minima, which has been predicted as the global minimum in the latest theoretical calculations. Also, this is the first experimental evidence for electronomers'. (author)

  15. A laser ablation ion source for the FRS ion catcher

    Energy Technology Data Exchange (ETDEWEB)

    Rink, Ann-Kathrin; Ebert, Jens; Petrick, Martin; Reiter, Pascal [Justus Liebig Universitaet Giessen (Germany); Dickel, Timo; Geissel, Hans; Plass, Wolfgang; Scheidenberger, Christoph [Justus Liebig Universitaet Giessen (Germany); GSI, Darmstadt (Germany); Purushothamen, Sivaji [GSI, Darmstadt (Germany)

    2013-07-01

    The FRS Ion Catcher was developed to serve as test bench for the low energy branch of the Super FRS to slow down exotic nuclei and prepare them for further measurements/ experiments. It consists of a cryogenic stopping cell to thermalise the ions, a diagnostic unit for stopping cell characterisation and various radiofrequency quadrupole structures to guide the ions to the Multiple-Reflection Time-of-Flight Mass Spectrometer for mass measurements, α spectroscopy and isobar separation. To characterise the extraction times of the stopping cell, which is one of the main performance parameters of such a cell, a laser ablation ion source has been develped and tested. This ion source provides a sharply defined starting point of the ions for the extraction time measurement. In the future this source will provide reference ions to calibrate the mass spectrometer for accurate mass measurements.

  16. Comparison of the Effectiveness of Ablative and Non-Ablative Fractional Laser Treatments for Early Stage Thyroidectomy Scars

    Directory of Open Access Journals (Sweden)

    Jin-Uk Jang

    2016-11-01

    Full Text Available BackgroundOpen thyroidectomy is conventionally performed at the anterior side of neck, which is a body part with a comparatively great degree of open exposure; due to this, postoperative scarring may cause distress in patients. We aimed to compare the effects of ablative and nonablative fractional laser treatments on thyroidectomy scars. We examined medical records in a retrospective manner and analyzed scars based on their digital images by using the modified Manchester Scar Scale (mMSS.MethodsBetween February 2012 and May 2013, 55 patients with thyroidectomy scars were treated with ablative (34 patients or nonablative (21 patients fractional laser. Each patient underwent 4 laser treatment sessions in 3–4 week intervals, 1–2 months postoperatively. Scar improvement was assessed using patient images and the mMSS scale.ResultsThe mean decrease in scar score was 3.91 and 3.47 in the ablative and nonablative groups, respectively; the reduction between 2 groups did not exhibit any significant difference (P=0.16. We used the scale once again to individually evaluate scar attributes. The nonablative group accounted for a considerably higher color score value (P=0.03; the ablative group accounted for a considerably higher contour score value (P<0.01. Patient satisfaction was high and no complications occurred.ConclusionsBoth types of fractional laser treatments can be used successfully for thyroidectomy scar treatment with minimal complications; however, results indicate that higher effectiveness may be obtained from the use of ablative and nonablative lasers for hypertrophic scars and early erythematous scars, respectively. Therefore, the appropriate laser for scar treatment should be selected according to its specific characteristics.

  17. Stress assisted selective ablation of ITO thin film by picosecond laser

    Science.gov (United States)

    Farid, Nazar; Chan, Helios; Milne, David; Brunton, Adam; M. O'Connor, Gerard

    2018-01-01

    Fast selective pattering with high precession on 175 nm ITO thin film with IR ps lasers is investigated. Ablation parameters are optimized with detailed studies on the scribed depth, topography, and particle generation using AFM and SEM. A comparison of 10 and 150 ps laser revealed that the shorter pulse (10 ps) laser is more appropriate in selective and partial ablation; up to 20 nm resolution for controlled depth with multipulses having energy below the damage threshold is demonstrated. The experimental results are interpreted to involve stress assisted ablation mechanism for the 10 ps laser while thermal ablation along with intense melting occurs for 150 ps laser. The transition between these regimes is estimated to occur at approximately 30 ps.

  18. Signal intensity enhancement of laser ablated volume holograms

    Science.gov (United States)

    Versnel, J. M.; Williams, C.; Davidson, C. A. B.; Wilkinson, T. D.; Lowe, C. R.

    2017-11-01

    Conventional volume holographic gratings (VHGs) fabricated in photosensitive emulsions such as gelatin containing silver salts enable the facile visualization of the holographic image in ambient lighting. However, for the fabrication of holographic sensors, which require more defined and chemically-functionalised polymer matrices, laser ablation has been introduced to create the VHGs and thereby broaden their applications, although the replay signal can be challenging to detect in ambient lighting. When traditional photochemical bleaching solutions used to reduce light scattering and modulate refractive index within the VHG are applied to laser ablated volume holographic gratings, these procedures decrease the holographic peak intensity. This is postulated to occur because both light and dark fringes contain a proportion of metal particles, which upon solubilisation are converted immediately to silver iodide, yielding no net refractive index modulation. This research advances a hypothesis that the reduced intensity of holographic replay signals is linked to a gradient of different sized metal particles within the emulsion, which reduces the holographic signal and may explain why traditional bleaching processes result in a reduction in intensity. In this report, a novel experimental protocol is provided, along with simulations based on an effective medium periodic 1D stack, that offers a solution to increase peak signal intensity of holographic sensors by greater than 200%. Nitric acid is used to etch the silver nanoparticles within the polymer matrix and is thought to remove the smaller particles to generate more defined metal fringes containing a soluble metal salt. Once the grating efficiency has been increased, this salt can be converted to a silver halide, to modulate the refractive index and increase the intensity of the holographic signal. This new protocol has been tested in a range of polymer chemistries; those containing functional groups that help to

  19. Mass spectrometric study of carbon cluster formation in laser ablation of graphite at 355 nm

    CERN Document Server

    Koo, Y M; Lee, K H; Jung, K W

    2002-01-01

    The ablation dynamics and cluster formation of C sub n sup + ions ejected from 355 nm laser ablation of a graphite target in vacuum are investigated using a reflectron time-of-flight (RTOF) mass spectrometer. At low laser fluence, odd-numbered cluster ions with 3 =30) are produced at relatively long delay times, indicating that atoms or small carbon clusters aggregate during plume propagation. The dependence of the intensity of ablated C sub n sup + ions on delay time after laser irradiation shows that the most probable velocity of each cluster ion decreases with cluster size.

  20. Laser ablation of lysozyme with UV, visible and infrared femto- and nanosecond pulses

    DEFF Research Database (Denmark)

    Schou, Jørgen; Canulescu, Stela; Matei, Andreea

    Lysozyme is an interesting molecule for laser ablation of organic materials, because the ablation has been comprehensively studied, it is a medium heavy molecule with a mass of 14305 Da, which can be detected by standard techniques, and because it is used as a bactericidal protein in the food...... industry. Lysozyme molecules do not absorb energy for wavelengths above 310 nm, but nevertheless there is a strong mass loss by ablation for laser irradiation in the visible regime. The total ablation yield of lysozyme at 355 nm and at 2 J/cm2 is about 155 µg/pulse, possibly one of the highest ablation...... yields ever measured. The mass loss is mainly caused by fragmentation of the lysozyme into simple gases, such as H2S, H2O and CO2 , which are rapidly pumped away in the vacuum chamber. We have investigated the mass loss by ablation of lysozyme in all regimes to see whether a similar mechanism governs...

  1. Preparation of Graphene Oxide Stabilized Nickel Nanoparticles with Thermal Effusivity Properties by Laser Ablation Method

    OpenAIRE

    Sadrolhosseini, Amir Reza; Noor, A. S. M.; Shameli, Kamyar; Kharazmi, Alireza; Huang, N. M.; Mahdi, M. A.

    2013-01-01

    Nickel nanoparticles were dispersed uniformly in a graphene oxide solution, using a laser ablation technique with different ablation times that ranged from 5 to 20 minutes. The results indicate that the nickel nanoparticle sizes inside the graphene oxide decreased, and the volume fraction for the nickel nanoparticles in the graphene oxide increased with an increasing ablation time. Further, using Fourier Transform Infrared Spectroscopy, the nickel nanoparticles in the graphene oxide demonstra...

  2. Experimental and theoretical studies of picosecond laser interactions with electronic materials-laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Samuel S. [Univ. of California, Berkeley, CA (United States)

    2000-05-01

    Lasers having picosecond and shorter pulse duration are receiving much attention due to their capabilities for direct-write micromachining on many materials with minimal substrate damage. Substantial progress has been made in the understanding of laser ablation processes, particularly the creation of plasmas that often shield the target and reduce the material processing efficiency at nanosecond time scales. However, a considerable challenge that still remains is the understanding of the underlying mechanisms during picosecond laser interactions with electronic solids. In this work we first study picosecond laser-induced electron emission from semiconductor surfaces. A theoretical model was set up based on carrier transport inside the semiconductor material during picosecond laser-semiconductor interactions. We demonstrate that nonequilibrium carrier dynamics plays a significant role for picosecond, as well as short nanosecond, laser induced electron emission from semiconductors. Photoelectric effect is found to be responsible for electron emission at low incident laser fluences, whereas thermionic emission is dominant at higher fluences. We have also performed experimental and theoretical studies on the formation and subsequent evolution of plasmas during laser-metal interactions at the picosecond time scale. Using picosecond time-resolved shadowgrams ahd interferograms, a novel type of plasma is observed, which has an electron density on the order of 1020cm-3.The origin of this picosecond plasma is attributed to gas breakdown, which is caused by laser-induced electron emission fi-om the target surface. After the laser pulse is completed, the longitudinal expansion of the plasma is suppressed. This suppression is found to result from an electric field above the target that prevents, after laser irradiation, fbrther movement of the electrons inside the plasma. Measurements of lateral plasma expansion indicate that the picosecond plasma may absorb

  3. Molecular signatures in femtosecond laser-induced organic plasmas: comparison with nanosecond laser ablation.

    Science.gov (United States)

    Serrano, Jorge; Moros, Javier; Laserna, J Javier

    2016-01-28

    During the last few years, laser-induced breakdown spectroscopy (LIBS) has evolved significantly in the molecular sensing area through the optical monitoring of emissions from organic plasmas. Large efforts have been made to study the formation pathways of diatomic radicals as well as their connections with the bonding framework of molecular solids. Together with the structural and chemical-physical properties of molecules, laser ablation parameters seem to be closely tied to the observed spectral signatures. This research focuses on evaluating the impact of laser pulse duration on the production of diatomic species that populate plasmas of organic materials. Differences in relative intensities of spectral signatures from the plasmas of several organic molecules induced in femtosecond (fs) and nanosecond (ns) ablation regimes have been studied. Beyond the abundance and origin of diatomic radicals that seed the plasma, findings reveal the crucial role of the ablation regime in the breakage pattern of the molecule. The laser pulse duration dictates the fragments and atoms resulting from the vaporized molecules, promoting some formation routes at the expense of other paths. The larger amount of fragments formed by fs pulses advocates a direct release of native bonds and a subsequent seeding of the plasma with diatomic species. In contrast, in the ns ablation regime, the atomic recombinations and single displacement processes dominate the contribution to diatomic radicals, as long as atomization of molecules prevails over their progressive decomposition. Consequently, fs-LIBS better reflects correlations between strengths of emissions from diatomic species and molecular structure as compared to ns-LIBS. These new results entail a further step towards the specificity in the analysis of molecular solids by fs-LIBS.

  4. Modeling CO2 laser ablation impulse of polymers in vapor and plasma regimes

    International Nuclear Information System (INIS)

    Sinko, John E.; Phipps, Claude R.

    2009-01-01

    An improved model for CO 2 laser ablation impulse in polyoxymethylene and similar polymers is presented that describes the transition effects from the onset of vaporization to the plasma regime in a continuous fashion. Several predictions are made for ablation behavior.

  5. Plasma luminescence feedback control system for precise ultrashort pulse laser tissue ablation

    Science.gov (United States)

    Kim, Beop-Min; Feit, Michael D.; Rubenchik, Alexander M.; Gold, David M.; Darrow, Christopher B.; Marion, John E., II; Da Silva, Luiz B.

    1998-05-01

    Plasma luminescence spectroscopy was used for precise ablation of bone tissue without damaging nearby soft tissue using an ultrashort pulse laser. Strong contrast of the luminescence spectra between bone marrow and spinal cord provided the real time feedback control so bone tissue is selectively ablated while preserving the spinal cord.

  6. CO2 TEA Laser-Enhanced Laser Ablation Molecular Isotopic Spectrometry (TELLAMIS)

    Science.gov (United States)

    Brown, Staci R.; Akpovo, Charlemagne A.; Ford, Alan; Herbert, Kenley; Johnson, Lewis

    2014-03-01

    Recently, it has been shown that the relative abundance of isotopes in enriched materials can be determined via laser-induced breakdown spectroscopy (LIBS) in a technique known as laser-ablation molecular isotopic spectroscopy (LAMIS). The original LAMIS work has focused on single-pulse (SP) LIBS for the excitation. However, dual-pulse (DP) LIBS reduces shot-to-shot variation and can lower detection limits of an element by about an order of magnitude or more. It also has the potential to improve the accuracy of the determination of the relative abundances of isotopes in LAMIS by minimizing the signal-to-noise ratio. In this work, a DP-LIBS technique for improving LAMIS relative-abundance information from a sample is presented. The new technique, called (TEA) Transverse-Excited breakdown in Atmosphere Laser-Enhanced Laser Ablation Molecular Isotopic Spectrometry (TELLAMIS), uses a carbon dioxide (CO2) laser to increase the breakdown emission from LIBS in the LAMIS method. This technique is demonstrated on a collection of relative abundance isotopes of boron- 10 and boron-11 in varying concentrations in boric acid. Least-squares fitting to theoretical models are used to deduce plasma parameters and understand reproducibility of results. DTRA.

  7. Experimental investigation on thermal ablation of carbon-fiber/epoxy composite irradiated by continuous wave laser

    Science.gov (United States)

    He, Minbo; Ma, Zhiliang; Chen, Linzhu; Lin, Xinwei; Zhou, Menglian

    2015-05-01

    The tests of carbon-fiber/epoxy composite laminates, subjected to a tangential gas-flow and 1070 nm continuous wave laser are carried out to acquire the ablation laws of samples on the conditions of different gas-flow. Simultaneously, considered the images from camera of large dynamic range, the damage laws of samples are also obtained for various laser power densities. Experimental results reveal that, without airflow on sample surface, the smoke caused by laser heating can be quickly on fire which causes a burn damage on the surface of samples so that the mass loss is most of all. However, the tangential airflow can remove away the smoke which has a weakening effect on the energy of incidence laser. So the ablation depth has an obvious increase in laser irradiation area. Unlike airflow, nitrogen flow can obviously restrain oxidation ablation on surface so that the ablation damage in laser irradiation area is relatively not severe. On the other hand, as laser power density increases, the mass loss of samples continues to rise but isn't proportional. And the ablation heat with the increase of power density shows a complex change. Below power density of 390 W/cm2, the mass loss mainly depends on the pyrolysis of epoxy while the ablation heat has a gradual decrease. Along with power density increasing but less than 1330 W/cm2 , the oxidation ablation of carbon fibers will be a leading factor and the ablation heat shows a little increase. Above power density of 1330 W/cm2 , the carbon fibers turn up the phenomenon of sublimation. What's more, airflow removed effects will be enhanced in high temperature. In this case, the ablation heat again has a trend of decrease.

  8. Water Vapour Propulsion Powered by a High-Power Laser-Diode

    Science.gov (United States)

    Minami, Y.; Uchida, S.

    Most of the laser propulsion schemes now being proposed and developed assume neither power supplies nor on-board laser devices and therefore are bound to remote laser stations like a kite via a laser beam “string”. This is a fatal disadvantage for a space vehicle that flies freely though it is often said that no need of installing an energy source is an advantage of a laser propulsion scheme. The possibility of an independent laser propulsion space vehicle that carries a laser source and a power supply on board is discussed. This is mainly due to the latest development of high power laser diode (LD) technology. Both high specific impulse-low thrust mode and high thrust-low specific impulse mode can be selected by controlling the laser output by using vapour or water as a propellant. This mode change can be performed by switching between a high power continuous wave (cw), LD engine for high thrust with a low specific impulse mode and high power LD pumping Q-switched Nd:YAG laser engine for low thrust with the high specific impulse mode. This paper describes an Orbital Transfer Vehicle equipped with the above-mentioned laser engine system and fuel cell that flies to the Moon from a space platform or space hotel in Earth orbit, with cargo shipment from lunar orbit to the surface of the Moon, including the possibility of a sightseeing trip.

  9. Reactive Laser-induced Ablation as Approach to Titanium Oxycarbide Films

    Czech Academy of Sciences Publication Activity Database

    Jandová, Věra; Fajgar, Radek; Dytrych, Pavel; Koštejn, Martin; Dřínek, Vladislav; Kupčík, Jaroslav

    2015-01-01

    Roč. 590, SEP 1 (2015), s. 270-275 ISSN 0040-6090 Institutional support: RVO:67985858 Keywords : IR laser * reactive ablation * titanium ethoxide Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.761, year: 2015

  10. Clinical risk factors to predict deep venous thrombosis post-endovenous laser ablation of saphenous veins.

    Science.gov (United States)

    Chi, Y-W; Woods, T C

    2014-04-01

    Endovenous laser ablation of saphenous veins is an alternative in treating symptomatic varicose veins. Deep venous thrombosis (DVT) has been reported in up to 7.7% of patients undergoing such procedure. We sought to establish clinical risk factors that predict DVT post-endovenous laser ablation. Patients who underwent endovenous laser ablation were prospectively followed. Clinical data and post-interventional duplex ultrasound were analysed. A P value 66 (P = 0.007), female gender (P = 0.048) and prior history of superficial thrombophlebitis (SVT) (P = 0.002) were associated with increased risk of DVT postprocedure. Age >66, female gender and history of SVT were significant predictors of DVT post-endovenous laser ablation of saphenous veins.

  11. Laser ablation of polymer coatings allows for electromagnetic field enhancement mapping around nanostructures

    DEFF Research Database (Denmark)

    Fiutowski, Jacek; Maibohm, Christian; Kjelstrup-Hansen, Jakob

    2011-01-01

    Subdiffraction spatially resolved, quantitative mapping of strongly localized field intensity enhancement on gold nanostructures via laser ablation of polymer thin films is reported. Illumination using a femtosecond laser scanning microscope excites surface plasmons in the nanostructures. The acc......Subdiffraction spatially resolved, quantitative mapping of strongly localized field intensity enhancement on gold nanostructures via laser ablation of polymer thin films is reported. Illumination using a femtosecond laser scanning microscope excites surface plasmons in the nanostructures....... The accompanying field enhancement substantially lowers the ablation threshold of the polymer film and thus creates local ablation spots and corresponding topographic modifications of the polymer film. Such modifications are quantified straightforwardly via scanning electron microscopy and atomic force microscopy...

  12. Oxidation and Carbidation of Laser-Ablated Amorphized Ti Particles in Carbon Monoxide

    Czech Academy of Sciences Publication Activity Database

    Jandová, Věra; Kupčík, Jaroslav; Bastl, Zdeněk; Šubrt, Jan; Pola, Josef

    2013-01-01

    Roč. 19, MAY (2013), s. 104-110 ISSN 1293-2558 Institutional support: RVO:67985858 ; RVO:61388980 ; RVO:61388955 Keywords : titanium * laser ablation * amorphization Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.679, year: 2013

  13. Nanopillar formation from two-shot femtosecond laser ablation of poly-methyl methacrylate

    Energy Technology Data Exchange (ETDEWEB)

    Baset, F.; Popov, K.; Villafranca, A.; Alshehri, A.M.; Guay, J.-M.; Ramunno, L.; Bhardwaj, V.R., E-mail: ravi.bhardwaj@uottawa.ca

    2015-12-01

    Highlights: • We studied morphological evolution and dynamics of two-pulse laser ablation in PMMA. • Nanopillar and volcanic eruption like structures are formed within the ablation crater. • Reflection of shockwave induced by the second laser pulse creates the structures. • Shockwave reflects from the boundary created by the first pulses. • Reflected shockwave causes density pinching in the middle of the ablation region. - Abstract: We present experimental and numerical studies on the morphological evolution and dynamics of femtosecond laser ablation of bulk poly-methyl methacrylate (PMMA) irradiated with a pair of pulses. We show that a nanopillar-like structure is formed in the middle of the ablation crater for pulse energies below single-shot ablation threshold. The nanopillar is ∼400 nm long, lies adjacent to a nanopore, and protrudes ∼150 nm above the sample surface. As the pulse energy is increased gradually, the nanopillar disappears and the nanopore inside the ablation crater becomes larger. At higher pulse energies, a volcanic eruption like structure appears in the middle of the crater whose size and height increases with energy. 2D molecular dynamics simulations reveal that a nanojet and other features observed at higher pulse energies can be formed when the reflection of a shockwave, induced by the second laser pulse, causes density pinching in the middle of the interaction region that rapidly pushes out molten material towards the surface. The shockwave is reflected from the cold boundaries of a modified region created by the first laser pulse.

  14. Spin-offs from laser ablation in art conservation

    Science.gov (United States)

    Asmus, J.; Elford, J.; Parfenov, V.

    2013-05-01

    In 1973 The Center for Art Conservation Studies (CASS) was established at the University of California, San Diego (UCSD). This was in response to demonstrations that were conducted during January-March 1972 in Venice for UNESCO, Venice in Peril, International Fund for Monuments, and the Italian Petroleum Institute (ENI). The feasibility investigation explored in-situ pulsed holography, holographic interferometry, and laser ablation divestment for applications in art conservation practice. During subsequent decades scores of UCSD graduate and undergraduate students as well as conservators, conservation scientists, academics, and engineers who resided in CASS as "Visiting Scholars" contributed to advancing the understanding and performance of radiation technologies in the arts. Several technologies in addition to those involving optical wavelengths were also investigated to aid in art conservation and conservation science. Magnetic Resonance Imaging (MRI) and Nuclear Magnetic Resonance (NMR) were employed to detect and map moisture within masonry. Lead isotopic analyses revealed authenticity and provenance of Benin bronzes. Inside-out x-ray radiography facilitated the detection of defects in stone. Ultrasonic imaging was introduced for the mapping of fresco strata. Photoacoustic Spectroscopy (PAS) was used to characterize varnish layers on paintings. Digital image processing was introduced in order to detect and visualize pentimenti within paintings as well as to perform virtual restoration and provide interactive museum displays. Holographic images were employed as imaginary theater sets. In the years that followed the graduation of students and the visits of professional collaborators, numerous other applications of radiation ablation began appearing in a wide variety of other fields such as aircraft maintenance, ship maintenance, toxic chemical remediation, biological sterilization, food processing, industrial fabrication, industrial maintenance, nuclear

  15. Advantages of dual-laser ablation in the growth of multicomponent thin films

    Science.gov (United States)

    Mukherjee, Devajyoti; Hyde, Robert; Mukherjee, Pritish; Witanachchi, Sarath

    2012-07-01

    We report the use of a dual-laser deposition process to grow stoichiometric films of the piezoelectric material PbZr0.52Ti0.48O3 (PZT) and the thermoelectric material Ba8Ga16Ge30. High volatility of Pb and Ba in these materials leads to non-stoichiometric growth in conventional PLD processes. Dual-laser ablation process preserves the Pb and Ba stoichiometry while significantly reducing the thickness variation and particulate density on the deposited films. This lead to the growth of smooth uniform films with enhanced ferroelectric and electrical properties. The dual-laser ablation combines the pulses of a KrF excimer laser (248 nm wavelength, 30 ns pulse width) and a CO2 laser (10.6 μm wavelength, 250 ns pulse width) where the beams are spatially overlapped on the ablation target and temporally delayed. At an optimum delay that is dependent on the physical properties of the material, CO2 pulse energy is coupled into the plume, generating a high temperature plasma (>25,000K). Laser-target interaction studies have shown the evaporation to be stoichiometric. Emission spectroscopy studies have shown ten-fold increase in emission intensities in dual-laser ablation while time-gated 2D ICCD imaging studies revealed the plume expansion to be stoichiometric over a large cone-angle of the plume under these conditions. Time-of-flight investigations in concert with hydrodynamic modeling provided a clear understanding of the mechanism of dual-laser ablation. Furthermore, plasma generated in the process is highly ionized (>75%) leading to films with high density and crystallinity. This paper will show the enhancement in properties attainable by the dual-laser ablation process in comparison to the single laser ablation.

  16. Particle size determination of silver nanoparticles generated by plasma laser ablation using a deconvolution method

    Czech Academy of Sciences Publication Activity Database

    Picciotto, A.; Torrisi, L.; Margarone, Daniele; Bellutti, P.

    2010-01-01

    Roč. 165, 6-10 (2010), s. 706-712 ISSN 1042-0150. [International Workshop on Pulsed Plasma Laser Ablation (PPLA)/4./. Monte Pieta, Messina, 18.06.2009-20.06.2009] Institutional research plan: CEZ:AV0Z10100522 Keywords : nanoparticles * plasma * laser ablation * surface plasmon resonance Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.660, year: 2010

  17. Thin film growing by the laser ablation technique: possibilities for growing of dosimetric materials

    International Nuclear Information System (INIS)

    Rojas R, E.M.; Melo M, M.; Enriquez Z, E.; Fernandez G, M.; Haro P, E.; Hernandez P, J.L.

    2005-01-01

    In this talk we will present the basics about the laser ablation technique and how it is used for thin film growing, either as a single film or a stack of thin films, as well as some methods to characterize in real time the film thickness. Finally, we will discuss the possibilities of using laser ablation for growing thin films with applications to dosimetry. (Author)

  18. Comprehensive studies of ultrashort laser pulse ablation of tin target at terawatt power

    Science.gov (United States)

    Elsied, Ahmed M.; Diwakar, Prasoon K.; Hassanein, Ahmed

    2018-01-01

    The fundamental properties of ultrashort laser interactions with metals using up to terawatt power were comprehensively studied, i.e., specifically mass ablation, nanoparticle formation, and ion dynamics using multitude of diagnostic techniques. Results of this study can be useful in many fields of research including spectroscopy, micromachining, thin film fabrication, particle acceleration, physics of warm dense matter, and equation-of-state determination. A Ti:Sapphire femtosecond laser system (110 mJ maximum energy, 40 fs, 800 nm, P-polarized, single pulse mode) was used, which delivered up to 3 terawatt laser power to ablate 1 mm tin film in vacuum. The experimental analysis includes the effect of the incident laser fluence on the ablated mass, size of the ablated area, and depth of ablation using white light profilometer. Atomic force microscope was used to measure the emitted particles size distribution at different laser fluence. Faraday cup (FC) detector was used to analyze the emitted ions flux by measuring the velocity, and the total charge of the emitted ions. The study shows that the size of emitted particles follows log-normal distribution with peak shifts depending on incident laser fluence. The size of the ablated particles ranges from 20 to 80 nm. The nanoparticles deposited on the wafer tend to aggregate and to be denser as the incident laser fluence increases as shown by AFM images. Laser ablation depth was found to increase logarithmically with laser fluence then leveling off at laser fluence > 400 J/cm2. The total ablated mass tends to increase logarithmically with laser fluence up to 60 J/cm2 while, increases gradually at higher fluence due to the increase in the ablated area. The measured ion emitted flux shows a linear dependence on laser fluence with two distinct regimes. Strong dependence on laser fluence was observed at fluences < 350 J/cm2. Also, a slight enhancement in ion velocity was observed with increasing laser fluence up to 350 J

  19. Laser-ablation-based ion source characterization and manipulation for laser-driven ion acceleration

    Science.gov (United States)

    Sommer, P.; Metzkes-Ng, J.; Brack, F.-E.; Cowan, T. E.; Kraft, S. D.; Obst, L.; Rehwald, M.; Schlenvoigt, H.-P.; Schramm, U.; Zeil, K.

    2018-05-01

    For laser-driven ion acceleration from thin foils (∼10 μm–100 nm) in the target normal sheath acceleration regime, the hydro-carbon contaminant layer at the target surface generally serves as the ion source and hence determines the accelerated ion species, i.e. mainly protons, carbon and oxygen ions. The specific characteristics of the source layer—thickness and relevant lateral extent—as well as its manipulation have both been investigated since the first experiments on laser-driven ion acceleration using a variety of techniques from direct source imaging to knife-edge or mesh imaging. In this publication, we present an experimental study in which laser ablation in two fluence regimes (low: F ∼ 0.6 J cm‑2, high: F ∼ 4 J cm‑2) was applied to characterize and manipulate the hydro-carbon source layer. The high-fluence ablation in combination with a timed laser pulse for particle acceleration allowed for an estimation of the relevant source layer thickness for proton acceleration. Moreover, from these data and independently from the low-fluence regime, the lateral extent of the ion source layer became accessible.

  20. Human cornea wound healing in organ culture after Er:YAG laser ablation

    Science.gov (United States)

    Shen, Jin-Hui; Joos, Karen M.; Robinson, Richard D.; Shetlar, Debra J.; O'Day, Denis M.

    1998-06-01

    Purpose: To study the healing process in cultured human corneas after Er:YAG laser ablation. Methods: Human cadaver corneas within 24 hours post mortem were ablated with a Q- switched Er:YAG laser at 2.94 micrometer wavelength. The radiant exposure was 500 mJ/cm2. The cornea was cultured on a tissue supporting frame immediately after the ablation. Culture media consisted of 92% minimum essential media, 8% fetal bovine serum, 0.125% HEPES buffer solution, 0.125% gentamicin, and 0.05% fungizone. The entire tissue frame and media container were kept in an incubator at 37 degrees Celsius and 5% CO2. Serial macroscopic photographs of the cultured corneas were taken during the healing process. Histology was performed after 30 days of culture. Results: A clear ablated crater into the stroma was observed immediately after the ablation. The thickness of thermal damage ranges between 1 and 25 micrometer. Haze development within the crater varies from the third day to the fourteenth day according to the depth and the roughness of the crater. Histologic sections of the cultured cornea showed complete re- epithelization of the lased area. Loose fibrous tissue is observed filling the ablated space beneath the epithelium. The endothelium appeared unaffected. Conclusions: The intensity and time of haze development appears dependent upon the depth of the ablation. Cultured human corneas may provide useful information regarding the healing process following laser ablation.

  1. Molybdenum oxide nanocolloids prepared by an external field-assisted laser ablation in water

    Directory of Open Access Journals (Sweden)

    Spadaro Salvatore

    2018-01-01

    Full Text Available he synthesis of extremely stable molybdenum oxide nanocolloids by pulsed laser ablation was studied. This green technique ensures the formation of contaminant-free nanostructures and the absence of by-products. A focused picosecond pulsed laser beam was used to ablate a solid molybdenum target immersed in deionized water. Molybdenum oxide nearly spherical nanoparticles with dimensions within few nanometers (20-100 nm are synthesized when the ablation processes were carried out, in water, at room temperature and 80°C. The application of an external electric field during the ablation process induces a nanostructures reorganization, as indicated by Scanning-Transmission Electron Microscopy images analysis. The ablation products were also characterized by some spectroscopic techniques: conventional UV-vis optical absorption, atomic absorption, dynamic light scattering, micro-Raman and X-ray photoelectron spectroscopies. Finally, NIH/3T3 mouse fibroblasts were used to evaluate cell viability by the sulforhodamine B assay

  2. Laser wavelength dependent properties of YBa2Cu3O7-δ thin films deposited by laser ablation

    International Nuclear Information System (INIS)

    Koren, G.; Gupta, A.; Baseman, R.J.; Lutwyche, M.I.; Laibowitz, R.B.

    1989-01-01

    YBa 2 Cu 3 O 7-δ thin films were deposited onto (100) SrTiO 3 substrates using 1064, 532, 355, 248, and 193 nm laser ablation. Transport measurements show lower normal-state resistivities and higher critical currents in films deposited by the shorter wavelength lasers. The surface morphology of the films was rough with large particulates when the 1064 nm laser was used whereas much smoother surfaces with fewer and smaller particulates were obtained with the UV lasers. It is suggested that the better film quality obtained when the UV lasers are used is due to a small absorption depth of the UV photons in the ceramic target and to higher absorption by the ablated fragments. This leads to smaller ablated species and further fragmentation in the hotter plume and, therefore, to smoother and denser films

  3. Treatment planning for prostate focal laser ablation in the face of needle placement uncertainty

    Energy Technology Data Exchange (ETDEWEB)

    Cepek, Jeremy, E-mail: jcepek@robarts.ca; Fenster, Aaron [Robarts Research Institute, London, Ontario N6A 5K8, Canada and Biomedical Engineering, The University of Western Ontario, London, Ontario N6A 5B9 (Canada); Lindner, Uri; Trachtenberg, John [Department of Surgical Oncology, Division of Urology, University Health Network, Toronto, Ontario M5G 2C4 (Canada); Davidson, Sean R. H. [Ontario Cancer Institute, University Health Network, Toronto, Ontario M5G 2M9 (Canada); Haider, Masoom A. [Department of Medical Imaging, Sunnybrook Health Sciences Center, Toronto, Ontario M4N 3M5, Canada and Department of Medical Imaging, University of Toronto, Toronto, Ontario M5S 2J7 (Canada); Ghai, Sangeet [Department of Medical Imaging, University Health Network, Toronto, Ontario M5G 2M9 (Canada)

    2014-01-15

    Purpose: To study the effect of needle placement uncertainty on the expected probability of achieving complete focal target destruction in focal laser ablation (FLA) of prostate cancer. Methods: Using a simplified model of prostate cancer focal target, and focal laser ablation region shapes, Monte Carlo simulations of needle placement error were performed to estimate the probability of completely ablating a region of target tissue. Results: Graphs of the probability of complete focal target ablation are presented over clinically relevant ranges of focal target sizes and shapes, ablation region sizes, and levels of needle placement uncertainty. In addition, a table is provided for estimating the maximum target size that is treatable. The results predict that targets whose length is at least 5 mm smaller than the diameter of each ablation region can be confidently ablated using, at most, four laser fibers if the standard deviation in each component of needle placement error is less than 3 mm. However, targets larger than this (i.e., near to or exceeding the diameter of each ablation region) require more careful planning. This process is facilitated by using the table provided. Conclusions: The probability of completely ablating a focal target using FLA is sensitive to the level of needle placement uncertainty, especially as the target length approaches and becomes greater than the diameter of ablated tissue that each individual laser fiber can achieve. The results of this work can be used to help determine individual patient eligibility for prostate FLA, to guide the planning of prostate FLA, and to quantify the clinical benefit of using advanced systems for accurate needle delivery for this treatment modality.

  4. Iron and iron oxide nanoparticles obtained by ultra-short laser ablation in liquid

    Energy Technology Data Exchange (ETDEWEB)

    De Bonis, A., E-mail: angela.debonis@unibas.it [Dipartimento di Scienze, Università della Basilicata, Viale dell’Ateneo Lucano, 10 – 85100 Potenza (Italy); Lovaglio, T.; Galasso, A. [Dipartimento di Scienze, Università della Basilicata, Viale dell’Ateneo Lucano, 10 – 85100 Potenza (Italy); Santagata, A. [CNR-ISM, U.O.S di Potenza, Zona Industriale di Tito, 85050 Tito Scalo (PZ) (Italy); Teghil, R. [Dipartimento di Scienze, Università della Basilicata, Viale dell’Ateneo Lucano, 10 – 85100 Potenza (Italy)

    2015-10-30

    Highlights: • Laser ablation of a iron target in water and acetone performed by an ultra-short laser source has been reported. • The size distributions of the obtained nanoparticles have been related to the ablation dynamics. • The formation of a graphitic shell prevents the oxidation of the iron nanoparticles. - Abstract: Laser ablation of an iron target in water and acetone has been carried out using a frequency doubled Nd:glass laser source (pulse duration of 250 fs and frequency repetition rate of 10 Hz). The observation of the nanostructures formed in the laser irradiated region of the metallic target and fast shadowgraphic analysis of the laser induced cavitation bubble have been performed in order to correlate the size distribution of the obtained nanoparticles to the dynamics of the ablation process. The composition, morphology and oxidation state of the synthesized nanoproducts have been investigated by XPS (X-ray Photoelectron Spectroscopy), TEM (Transmission Electron Microscopy) and microRaman spectroscopy. The experimental data support a relationship between the nanoparticles size distribution and the femtosecond laser ablation mechanism, while the chemical and structural characteristics of the nanoparticles can be tuned by varying the liquid medium.

  5. Iron and iron oxide nanoparticles obtained by ultra-short laser ablation in liquid

    International Nuclear Information System (INIS)

    De Bonis, A.; Lovaglio, T.; Galasso, A.; Santagata, A.; Teghil, R.

    2015-01-01

    Highlights: • Laser ablation of a iron target in water and acetone performed by an ultra-short laser source has been reported. • The size distributions of the obtained nanoparticles have been related to the ablation dynamics. • The formation of a graphitic shell prevents the oxidation of the iron nanoparticles. - Abstract: Laser ablation of an iron target in water and acetone has been carried out using a frequency doubled Nd:glass laser source (pulse duration of 250 fs and frequency repetition rate of 10 Hz). The observation of the nanostructures formed in the laser irradiated region of the metallic target and fast shadowgraphic analysis of the laser induced cavitation bubble have been performed in order to correlate the size distribution of the obtained nanoparticles to the dynamics of the ablation process. The composition, morphology and oxidation state of the synthesized nanoproducts have been investigated by XPS (X-ray Photoelectron Spectroscopy), TEM (Transmission Electron Microscopy) and microRaman spectroscopy. The experimental data support a relationship between the nanoparticles size distribution and the femtosecond laser ablation mechanism, while the chemical and structural characteristics of the nanoparticles can be tuned by varying the liquid medium.

  6. Comparison of transcatheter laser and direct-current shock ablation of endocardium near tricuspid anulus

    Science.gov (United States)

    Zhang, Yu-Zhen; Wang, Shi-Wen; Li, Junheng

    1993-03-01

    Forty to eighty percent of the patients with accessory pathways (APs) manifest themselves by tachyarrhythmias. Many of these patients needed either life-long medical therapy or surgery. In order to avoid the discomfort and expenses in surgical procedures, closed chest percutaneous catheter ablation of APs became a potentially desirable therapeutic approach. Many investigations indicated that ablation of right APs by transcatheter direct current (dc) shock could cause life-threatening arrhythmias, right coronary arterical (RCA) spasm, etc. With the development of transcatheter laser technique, it has been used in drug-incurable arrhythmias. The results show that laser ablation is much safer than surgery and electric shock therapy. The purpose of this study is to explore the effectiveness, advantages, and complications with transcatheter Nd:YAG laser and dc shock in the ablation of right atrioventricular accessory pathways in the atrium near the tricuspid annulus (TA) in 20 dogs.

  7. Laboratory experiments on the formation and recoil jet transport of aerosol by laser ablation

    Science.gov (United States)

    Hirooka, Yoshi; Tanaka, Kazuo A.; Imamura, Keisuke; Okazaki, Katsuya

    2016-05-01

    In a high-repetition rate inertial fusion reactor, the first wall will be subjected to repeated ablation along with pellet implosions, which then leads to the formation of aerosol to scatter and/or deflect laser beams for the subsequent implosion, affecting the overall reactor performance. Proposed in the present work is a method of in-situ directed transport of aerosol particles by the use of laser ablation-induced jet recoil momenta. Lithium and carbon are used as the primary ablation targets, the former of which is known to form aerosol in the form of droplet, and the latter of which tends to form carbon nanotubes. Laboratory-scale experiments have been conducted to irradiate airborne aerosol particles with high-intensity laser to produce ablation-induced jet. Data have indicated a change in aerosol flow direction, but only in the case of lithium.

  8. Effects of picosecond laser repetition rate on ablation of Cr12MoV cold work mold steel

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Baoye; Deng, Leimin; Liu, Peng; Zhang, Fei; Duan, Jun, E-mail: duans@hust.edu.cn; Zeng, Xiaoyan

    2017-07-01

    In this paper, the effects of pulse repetition rate on ablation efficiency and quality of Cr12MoV cold work mold steel have been studied using a picosecond (ps) pulse Nd:YVO{sub 4} laser system at λ= 1064 nm. The experimental results of area ablation on target surface reveal that laser repetition rate plays a significant role in controlling ablation efficiency and quality. Increasing the laser repetition rate, while keeping a constant mean power improves the ablation efficiency and quality. For each laser mean power, there is an optimal repetition rate to achieve a higher laser ablation efficiency with low surface roughness. A high ablation efficiency of 42.29, 44.11 and 47.52 μm{sup 3}/mJ, with surface roughness of 0.476, 0.463 and 0.706 μm could be achieved at laser repetition rate of 10 MHz, for laser mean power of 15, 17 and 19 W, respectively. Scanning electron microcopy images revels that the surface morphology evolves from rough with numerous craters, to flat without pores when we increased the laser repetition rate. The effects of laser repetition rate on the heat accumulation, plasma shield and ablation threshold were analyzed by numerical simulation, spectral analysis and multi-laser shot, respectively. The synergetic effects of laser repetition rate on laser ablation rate and machining quality were analyzed and discussed systemically in this paper.

  9. An investigation on 800 nm femtosecond laser ablation of K9 glass in air and vacuum

    Science.gov (United States)

    Xu, Shi-zhen; Yao, Cai-zhen; Dou, Hong-qiang; Liao, Wei; Li, Xiao-yang; Ding, Ren-jie; Zhang, Li-juan; Liu, Hao; Yuan, Xiao-dong; Zu, Xiao-tao

    2017-06-01

    Ablation rates of K9 glass were studied as a function of femtosecond laser fluences. The central wavelength was 800 nm, and pulse durations of 35 fs and 500 fs in air and vacuum were employed. Ablation thresholds of 0.42 J/cm2 and 2.1 J/cm2 were obtained at 35 fs and 500 fs, respectively, which were independent with the ambient conditions and depend on the incident pulse numbers due to incubation effects. The ablation rate of 35 fs pulse laser increased with the increasing of laser fluence in vacuum, while in air condition, it slowly increased to a plateau at high fluence. The ablation rate of 500 fs pulse laser showed an increase at low fluence and a slow drop of ablation rate was observed at high fluence in air and vacuum, which may due to the strong defocusing effects associated with the non-equilibrium ionization of air, and/or the shielding effects of conduction band electrons (CBEs) produced by multi-photon ionization and impact ionization in K9 glass surface. The typical ablation morphologies, e.g. smooth zone and laser-induced periodic surface structures (LIPSS) were also presented and illustrated.

  10. Fully Automated Laser Ablation Liquid Capture Sample Analysis using NanoElectrospray Ionization Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, Matthias [ORNL; Ovchinnikova, Olga S [ORNL; Van Berkel, Gary J [ORNL

    2014-01-01

    RATIONALE: Laser ablation provides for the possibility of sampling a large variety of surfaces with high spatial resolution. This type of sampling when employed in conjunction with liquid capture followed by nanoelectrospray ionization provides the opportunity for sensitive and prolonged interrogation of samples by mass spectrometry as well as the ability to analyze surfaces not amenable to direct liquid extraction. METHODS: A fully automated, reflection geometry, laser ablation liquid capture spot sampling system was achieved by incorporating appropriate laser fiber optics and a focusing lens into a commercially available, liquid extraction surface analysis (LESA ) ready Advion TriVersa NanoMate system. RESULTS: Under optimized conditions about 10% of laser ablated material could be captured in a droplet positioned vertically over the ablation region using the NanoMate robot controlled pipette. The sampling spot size area with this laser ablation liquid capture surface analysis (LA/LCSA) mode of operation (typically about 120 m x 160 m) was approximately 50 times smaller than that achievable by direct liquid extraction using LESA (ca. 1 mm diameter liquid extraction spot). The set-up was successfully applied for the analysis of ink on glass and paper as well as the endogenous components in Alstroemeria Yellow King flower petals. In a second mode of operation with a comparable sampling spot size, termed laser ablation/LESA , the laser system was used to drill through, penetrate, or otherwise expose material beneath a solvent resistant surface. Once drilled, LESA was effective in sampling soluble material exposed at that location on the surface. CONCLUSIONS: Incorporating the capability for different laser ablation liquid capture spot sampling modes of operation into a LESA ready Advion TriVersa NanoMate enhanced the spot sampling spatial resolution of this device and broadened the surface types amenable to analysis to include absorbent and solvent resistant

  11. Characterization of ablated species in laser-induced plasma plume

    International Nuclear Information System (INIS)

    Furusawa, Hideki; Sakka, Tetsuo; Ogata, Yukio H.

    2004-01-01

    Plasma electron density and atomic population densities in the plasma plume produced by a laser ablation of aluminum metal were determined in various ambient gases at relatively high pressures. The method is based on the fit of a spectral line profile of Al(I) 2 P (convolutionsign) - 2 S emission to the theoretical spectrum obtained by one-dimensional radiative transfer calculation. The electron density was higher for a higher ambient gas pressure, suggesting the confinement of the plume by an ambient gas. The electron density also depends on the type of ambient gases, i.e., it increased in the order He 4 2 4 , while the atomic population density is almost independent of the type of ambient species and pressure. The population densities of the upper and lower levels of the transition were compared, and the ratio between their spatial distribution widths was calculated. These results provide valuable information regarding the confinement of the plume by the ambient gas and give insight into the time evolution of the plume

  12. Nonstoichiometric Titanium Oxides via Pulsed Laser Ablation in Water

    Directory of Open Access Journals (Sweden)

    Chen Shuei-Yuan

    2010-01-01

    Full Text Available Abstract Titanium oxide compounds TiO,Ti2O3, and TiO2 with a considerable extent of nonstoichiometry were fabricated by pulsed laser ablation in water and characterized by X-ray/electron diffraction, X-ray photoelectron spectroscopy and electron energy loss spectroscopy. The titanium oxides were found to occur as nanoparticle aggregates with a predominant 3+ charge and amorphous microtubes when fabricated under an average power density of ca. 1 × 108W/cm2 and 1011W/cm2, respectively followed by dwelling in water. The crystalline colloidal particles have a relatively high content of Ti2+ and hence a lower minimum band gap of 3.4 eV in comparison with 5.2 eV for the amorphous state. The protonation on both crystalline and amorphous phase caused defects, mainly titanium rather than oxygen vacancies and charge and/or volume-compensating defects. The hydrophilic nature and presumably varied extent of undercoordination at the free surface of the amorphous lamellae accounts for their rolling as tubes at water/air and water/glass interfaces. The nonstoichiometric titania thus fabricated have potential optoelectronic and catalytic applications in UV–visible range and shed light on the Ti charge and phase behavior of titania-water binary in natural shock occurrence.

  13. Antibacterial effect of bismuth subsalicylate nanoparticles synthesized by laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Flores-Castañeda, Mariela [Instituto Nacional de Investigaciones Nucleares (Mexico); Vega-Jiménez, Alejandro L., E-mail: argelia.almaguer@mac.com; Almaguer-Flores, Argelia [Universidad Nacional Autónoma de México, Facultad de Odontología, DEPeI, I (Mexico); Camps, Enrique; Pérez, Mario [Instituto Nacional de Investigaciones Nucleares (Mexico); Silva-Bermudez, Phaedra [Instituto Nacional de Rehabilitación, Unidad de Ingeniería de Tejidos, Terapia Celular y Medicina Regenerativa (Mexico); Berea, Edgardo [FarmaQuimia SA de CV. (Mexico); Rodil, Sandra E. [Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales (Mexico)

    2015-11-15

    The antimicrobial properties of bismuth subsalicylate (BSS) nanoparticles against four opportunistic pathogens; E. coli, P. aeruginosa, S. aureus, and S. epidermidis were determined. BSS nanoparticles were synthesized by pulse laser ablation of a solid target in distilled water under different conditions. The nanoparticles were characterized using high-resolution transmission electron microscopy and absorption spectra and small angle X-ray scattering. The analysis shows that the colloids maintained the BSS structure and presented average particle size between 20 and 60 nm, while the concentration ranges from 95 to 195 mg/L. The antibacterial effect was reported as the inhibition ratio of the bacterial growth after 24 h and the cell viability was measured using the XTT assay. The results showed that the inhibition ratio of E. coli and S. epidermidis was dependant on the NPs size and/or concentration, meanwhile P. aeruginosa and S. aureus were more sensitive to the BSS nanoparticles independently of both the size and the concentration. In general, the BSS colloids with average particle size of 20 nm were the most effective, attaining inhibition ratios >80 %, similar or larger than those obtained with the antibiotic used as control. The results suggest that the BSS colloids could be used as effective antibacterial agents with potential applications in the medical area.

  14. Antibacterial effect of bismuth subsalicylate nanoparticles synthesized by laser ablation

    Science.gov (United States)

    Flores-Castañeda, Mariela; Vega-Jiménez, Alejandro L.; Almaguer-Flores, Argelia; Camps, Enrique; Pérez, Mario; Silva-Bermudez, Phaedra; Berea, Edgardo; Rodil, Sandra E.

    2015-11-01

    The antimicrobial properties of bismuth subsalicylate (BSS) nanoparticles against four opportunistic pathogens; E. coli, P. aeruginosa, S. aureus, and S. epidermidis were determined. BSS nanoparticles were synthesized by pulse laser ablation of a solid target in distilled water under different conditions. The nanoparticles were characterized using high-resolution transmission electron microscopy and absorption spectra and small angle X-ray scattering. The analysis shows that the colloids maintained the BSS structure and presented average particle size between 20 and 60 nm, while the concentration ranges from 95 to 195 mg/L. The antibacterial effect was reported as the inhibition ratio of the bacterial growth after 24 h and the cell viability was measured using the XTT assay. The results showed that the inhibition ratio of E. coli and S. epidermidis was dependant on the NPs size and/or concentration, meanwhile P. aeruginosa and S. aureus were more sensitive to the BSS nanoparticles independently of both the size and the concentration. In general, the BSS colloids with average particle size of 20 nm were the most effective, attaining inhibition ratios >80 %, similar or larger than those obtained with the antibiotic used as control. The results suggest that the BSS colloids could be used as effective antibacterial agents with potential applications in the medical area.

  15. Real time determination of the laser ablated mass by means of electric field-perturbation measurement

    Science.gov (United States)

    Pacheco, P.; Álvarez, J.; Sarmiento, R.; Bredice, F.; Sánchez-Aké, C.; Villagrán-Muniz, M.; Palleschi, V.

    2018-04-01

    A Nd:YAG ns-pulsed laser was used to ablate Al, Cd and Zn targets, which were placed between the plates of a planar charged capacitor. The plasma generates a transient redistribution of the electrical charges on the plates that can be measured as a voltage drop across a resistor connected to the ground plate. This signal is proportional to the capacitor applied voltage, the distance between the plates and the total number of ions produced in the ablation process which in turn is related to the laser energy and the ablated mass. After a series of pulses, the targets were weighed on a thermogravimetric balance to measure the ablated mass. Our results show that the electrical signal measured on the resistor is univocally related to the ablated mass from the target. Therefore, after a proper calibration depending on the material and the experimental geometry, the electrical signal can be used for real time quantitative measurement of the ablated mass in pulsed laser generated plasma experiments. The experiments were repeated on an aluminum target, with and without the presence of the external electric field in order to determine the possible influence of the applied electric field on the ablated mass.

  16. Laser ablation as monotherapy for penile squamous cell carcinoma: A multi-center cohort analysis.

    Science.gov (United States)

    Tang, Dominic H; Yan, Sylvia; Ottenhof, Sarah R; Draeger, Désirée; Baumgarten, Adam S; Chipollini, Juan; Protzel, Chris; Zhu, Yao; Ye, Ding-Wei; Hakenberg, Oliver W; Horenblas, Simon; Watkin, Nicholas A; Spiess, Philippe E

    2017-10-30

    Although the trend towards penile sparing therapy is increasing for penile squamous cell carcinoma, outcomes for laser ablation therapy have not been widely reported. We assessed the clinical outcomes of penile cancer patients treated with only laser ablation. A retrospective review was performed on 161 patients across 5 multi-center tertiary referral centers from 1985 to 2015. All patients underwent penile sparing surgery with only laser ablation for squamous cell carcinoma of the penis. Laser ablation was performed with neodymium-doped yttrium aluminum garnet or carbon dioxide. Overall and recurrence-free survival was calculated using the Kaplan-Meier method and compared with the log rank test. A total of 161 patients underwent laser ablation for penile cancer. The median age was 62 (IQR: 52-71) years and median follow-up was 57.7 (IQR: 28-90) months. The majority of patients were pTa/Tis (59, 37%) or pT1a (62, 39%). Only 19 (12%) had a poorly differentiated grade. The 5-year recurrence-free survival was 46%. When stratified by stage, the 5-year local recurrence-free survival was pTa/Tis: 50%; pT1a: 41%; pT1b: 38%; and pT2: 52%. The inguinal/pelvic nodal recurrence was pTa/Tis: 2%; pT1a: 5%; pT1b: 18%; and pT2: 22%. There were no differences among stages with respect to recurrence-free survival (P = 0.98) or overall survival (P = 0.20). Laser ablation therapy is safe for appropriately selected patients with penile squamous cell carcinoma. Due to the increased risk of nodal recurrence, laser ablation coupled with diagnostic nodal staging is indicated for patients with pT1b or higher. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Single and double long pulse laser ablation of aluminum induced in air and water ambient

    Energy Technology Data Exchange (ETDEWEB)

    Akbari Jafarabadi, Marzieh; Mahdieh, Mohammad Hossein, E-mail: mahdm@iust.ac.ir

    2017-02-28

    Highlights: • Laser ablation of aluminum target by single and double pulse (∼ 5 ns delay) in ambient air and distilled water • Comparing with air, in ambient water, plasma confinement results in higher crater depth. • In comparison with single pulse laser ablation, the absorption of the laser pulse energy is higher for double pulse regime. • As a result of ablated material expansion, the crater depth is decreased if the target is placed at lower depth. - Abstract: In this paper, single pulse and double pulse laser ablation of an aluminum target in two interaction ambient was investigated experimentally. The interaction was performed by nanosecond Nd:YAG laser beam in air and four depths (i.e. 9, 13, 17, and 21 mm) of distilled water ambient. The irradiation was carried out in single and collinear double pulse configurations in both air and liquid ambient. Crater geometry (depth and diameter) was measured by an optical microscope. The results indicated that the crater geometry strongly depends on both single pulse and double pulse configurations and interaction ambient. In single pulse regime, the crater diameter is higher for all water depths compared to that of air. However, the crater depth, depend on water depth, is higher or lower than the crater depth in air. In double pulse laser ablation, there are greater values for both crater diameters and crater depths in the water.

  18. Angular distributions of emitted particles by laser ablation of silver at 355 nm

    DEFF Research Database (Denmark)

    Svendsen, Winnie Edith; Schou, Jørgen; Hansen, T.

    1998-01-01

    The angular distribution of laser ablated silver in vacuum has been measured in situ with an array of quartz-crystal microbalances. The silver surface was irradiated by ns pulses from a Nd:YAG laser operating at 355 nm for fluences ranging from 0.7 J/cm2 to 8 J/cm2. The distribution is strongly...

  19. IR laser ablative modification of poly(ethylene-co-acrylic acid) zinc salt

    Czech Academy of Sciences Publication Activity Database

    Blazevska-Gilev, J.; Šubrt, Jan; Bastl, Zdeněk; Pola, Josef

    2006-01-01

    Roč. 91, č. 12 (2006), s. 2834-2839 ISSN 0141-3910 Institutional research plan: CEZ:AV0Z40320502; CEZ:AV0Z40400503; CEZ:AV0Z40720504 Keywords : poly(ethylene-co-acrylic acid) zinc salt * laser ablation * laser degradation Subject RIV: CA - Inorganic Chemistry Impact factor: 2.174, year: 2006

  20. Two-dimensional fluorescence spectroscopy of uranium isotopes in femtosecond laser ablation plumes

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Mark C.; Brumfield, Brian E.; LaHaye, Nicole L.; Harilal, Sivanandan S.; Hartig, Kyle C.; Jovanovic, Igor

    2017-06-19

    We demonstrate measurement of uranium isotopes in femtosecond laser ablation plumes using two-dimensional fluorescence spectroscopy (2DFS). The high-resolution, tunable CW-laser spectroscopy technique clearly distinguishes atomic absorption from 235U and 238U in natural and highly enriched uranium metal samples. We present analysis of spectral resolution and analytical performance of 2DFS as a function of ambient pressure. Simultaneous measurement using time-resolved absorption spectroscopy provides information on temporal dynamics of the laser ablation plume and saturation behavior of fluorescence signals. The rapid, non-contact measurement is promising for in-field, standoff measurements of uranium enrichment for nuclear safety and security applications.

  1. Analysis and removal of ITER relevant materials and deposits by laser ablation

    International Nuclear Information System (INIS)

    Xiao, Qingmei; Huber, Alexander; Philipps, Volker; Sergienko, Gennady; Gierse, Niels; Mertens, Philippe; Hai, Ran; Ding, Hongbin

    2014-01-01

    The analysis of the deposition of eroded wall material on the plasma-facing materials in fusion devices is one of the crucial issues to maintain the plasma performance and to fulfill safety requirements with respect to tritium retention by co-deposition. Laser ablation with minimal damage to the plasma facing material is a promising method for in situ monitoring and removal of the deposition, especially for plasma-shadowed areas which are difficult to reach by other cleaning methods like plasma discharge. It requires the information of ablation process and the ablation threshold for quantitative analysis and effective removal of the different deposits. This paper presents systemic laboratory experimental analysis of the behavior of the ITER relevant materials, graphite, tungsten, aluminum (as a substitution of beryllium) and mixed deposits ablated by a Nd:YAG laser (1064 nm) with different energy densities (1–27 J/cm 2 , power density 0.3–3.9 GW/cm 2 ). The mixed deposits consisted of W–Al–C layer were deposited on W substrate by magnetron sputtering and arc plasma deposition. The aim was to select the proper parameters for the quantitative analysis and for laser removal of the deposits by investigating the ablation efficiency and ablation threshold for the bulk materials and deposits. The comparison of the ablation and saturation energy thresholds for pure and mixed materials shows that the ablation threshold of the mixed layer depends on the concentration of the components. We propose laser induced breakdown spectroscopy for determination of the elemental composition of deposits and then we select the laser parameters for the layer removal. Comparison of quantitative analysis results from laboratory to that from TEXTOR shows reasonable agreements. The dependence of the spectra on plasma parameters and ambient gas pressure is investigated

  2. Determination of ablation threshold for composite resins and amalgam irradiated with femtosecond laser pulses

    Science.gov (United States)

    Freitas, A. Z.; Freschi, L. R.; Samad, R. E.; Zezell, D. M.; Gouw-Soares, S. C.; Vieira, N. D., Jr.

    2010-03-01

    The use of laser for caries removal and cavity preparation is already a reality in the dental clinic. The objective of the present study was to consider the viability of ultrashort laser pulses for restorative material selective removal, by determining the ablation threshold fluence for composite resins and amalgam irradiated with femtosecond laser pulses. Lasers pulses centered at 830 nm with 50 fs of duration and 1 kHz of repetition rate, with energies in the range of 300 to 770 μJ were used to irradiate the samples. The samples were irradiated using two different geometrical methods for ablation threshold fluence determinations and the volume ablation was measured by optical coherence tomography. The shape of the ablated surfaces were analyzed by optical microscopy and scanning electron microscopy. The determined ablation threshold fluence is 0.35 J/cm2 for the composite resins Z-100 and Z-350, and 0.25 J/cm2 for the amalgam. These values are half of the value for enamel in this temporal regime. Thermal damages were not observed in the samples. Using the OCT technique (optical coherence tomography) was possible to determine the ablated volume and the total mass removed.

  3. Nanosecond laser ablation processes in aluminum-doped zinc-oxide for photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    Canteli, D., E-mail: david.canteli@ciemat.es [Division de Energias Renovables, Energia Solar Fotovoltaica, CIEMAT, Avda. Complutense, 22, 28040 Madrid (Spain); Fernandez, S. [Division de Energias Renovables, Energia Solar Fotovoltaica, CIEMAT, Avda. Complutense, 22, 28040 Madrid (Spain); Molpeceres, C. [Centro Laser, Universidad Politecnica de Madrid, Ctra. de Valencia Km 7.3, 28031 Madrid (Spain); Torres, I.; Gandia, J.J. [Division de Energias Renovables, Energia Solar Fotovoltaica, CIEMAT, Avda. Complutense, 22, 28040 Madrid (Spain)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer A study of the ablation of AZO thin films deposited at different temperature conditions with nanosecond UV laser light for photovoltaic devices has been performed. Black-Right-Pointing-Pointer The ablation threshold of AZO thin films was measured and related with the absorption coefficient of the films at the laser wavelength, showing a direct correspondence. Black-Right-Pointing-Pointer A change in the material structure in the areas closest to the edges of laser grooves made in samples deposited at temperatures below 100 Degree-Sign C was observed and studied. - Abstract: Aiming to a future use in thin film solar modules, the processing of aluminum doped zinc oxide thin films with good optoelectronic properties with a nanosecond-pulsed ultraviolet laser has been studied. The ablation threshold fluence of the films has been determined and associated with the material properties. The ablation process has been optimized and grooves with good properties for photovoltaic devices have been obtained. The morphology of the ablated surfaces has been observed by confocal microscopy and its structure has been characterized by Raman spectroscopy. The influence of ablation parameters like focus distance, pulse energy and repetition frequency in the groove morphology has been studied with special attention to the thermal effects on the material structure.

  4. Nanosecond laser ablation processes in aluminum-doped zinc-oxide for photovoltaic devices

    International Nuclear Information System (INIS)

    Canteli, D.; Fernandez, S.; Molpeceres, C.; Torres, I.; Gandía, J.J.

    2012-01-01

    Highlights: ► A study of the ablation of AZO thin films deposited at different temperature conditions with nanosecond UV laser light for photovoltaic devices has been performed. ► The ablation threshold of AZO thin films was measured and related with the absorption coefficient of the films at the laser wavelength, showing a direct correspondence. ► A change in the material structure in the areas closest to the edges of laser grooves made in samples deposited at temperatures below 100 °C was observed and studied. - Abstract: Aiming to a future use in thin film solar modules, the processing of aluminum doped zinc oxide thin films with good optoelectronic properties with a nanosecond-pulsed ultraviolet laser has been studied. The ablation threshold fluence of the films has been determined and associated with the material properties. The ablation process has been optimized and grooves with good properties for photovoltaic devices have been obtained. The morphology of the ablated surfaces has been observed by confocal microscopy and its structure has been characterized by Raman spectroscopy. The influence of ablation parameters like focus distance, pulse energy and repetition frequency in the groove morphology has been studied with special attention to the thermal effects on the material structure.

  5. Dentin ablation-rate measurements in endodontics witj HF and CO2 laser radiation

    Science.gov (United States)

    Makropoulou, Mersini I.; Serafetinides, Alexander A.; Khabbaz, Marouan; Sykaras, Sotirios; Tsikrikas, G. N.

    1996-01-01

    Recent studies focused on the ability of the laser light to enlarge the root canal during the endodontic therapy. The aim of this research is the experimental and theoretical study of the ablation rate of two infrared laser wavelengths on dentin. Thirty freshly extracted human teeth were longitudinally sectioned at thicknesses ranged from 0.5 to 2 mm, and irradiated on the root canal dentin. The measured ablation rates in dentinal wall of the root canal showed that the HF laser at 2.9 micrometer can more effectively penetrate into the tissue, whereas the carbon dioxide laser at 10.6 micrometer leads to high thermal damage of the ablation crater surroundings.

  6. Processing condition influence on the characteristics of gold nanoparticles produced by pulsed laser ablation in liquids

    International Nuclear Information System (INIS)

    Nikov, R.G.; Nikolov, A.S.; Nedyalkov, N.N.; Atanasov, P.A.; Alexandrov, M.T.; Karashanova, D.B.

    2013-01-01

    A study is presented of Au nanoparticles (NPs) created by nanosecond pulsed laser ablation of a solid target in double distilled water. The influence was examined of the laser wavelength on the size, shape and optical properties of the resulting NPs. Three different wavelengths: the fundamental (λ = 1064 nm), second (λ SHG = 532) and third (λ THG = 355) harmonic of a Nd:YAG laser at the same fluence were utilized to produce various colloids. Ablation at the wavelength of 532 nm was investigated in more detail to reveal the influence of self-absorption by the already created NPs on their characteristics. The colloid produced was irradiated by λ irrad = 532 nm (laser energy 40 mJ) at different times up to 25 min after the end of ablation. The initial structure of welded NPs forming wires was modified. Transmission electron microscopy and optical transmission measurements were used to evaluate the shape and size distribution of the NPs.

  7. Isotope analysis of micro metal particles by adopting laser-ablation mass spectrometry

    International Nuclear Information System (INIS)

    Song, Kyu Seok; Ha, Young Kyung; Han, Sun Ho; Park, Yong Joon; Kim, Won Ho

    2005-01-01

    The isotope analysis of microparticles in environmental samples as well as laboratory samples is an important task. A special concern is necessary in particle analysis of swipe samples. Micro particles are normally analyzed either by dissolving particles in the solvents and adopting conventional analytical methods or direct analysis method such as a laser-ablation ICP mass spectrometry (LA-ICP-MS), SIMS, and SNMS (sputtered neutral mass spectrometry). But the LA-ICPMS uses large amount of samples because normally laser beam is tightly focused on the target particle for the complete ablation. The SIMS and SNMS utilize ion beams for the generation of sample ions from the particle. But the number of ions generated by an ion beam is less than 5% of the total generated particles in SIMS. The SNMS is also an excellent analytical technique for particle analysis, however, ion beam and frequency tunable laser system are required for the analysis. Recently a direct analysis of elements as well as isotopes by using laser-ablation is recognized one of the most efficient detection technology for particle samples. The laser-ablation mass spectrometry requires only one laser source without frequency tuneability with no sample pretreatment. Therefore this technique is one of the simplest analysis techniques for solid samples as well as particles. In this study as a part of the development of the new isotope analysis techniques for particles samples, a direct laser-ablation is adopted with mass spectrometry. Zinc and gadolinium were chosen as target samples, since these elements have isotopes with minor abundance (0.62% for Zn, and 0.2% for Gd). The preliminary result indicates that isotopes of these two elements are analyzed within 10% of natural abundance with good mass resolution by using direct laser-ablation mass spectrometry

  8. Potassium titanyl phosphate laser tissue ablation: development and experimental validation of a new numerical model.

    Science.gov (United States)

    Elkhalil, Hossam; Akkin, Taner; Pearce, John; Bischof, John

    2012-10-01

    The photoselective vaporization of prostate (PVP) green light (532 nm) laser is increasingly being used as an alternative to the transurethral resection of prostate (TURP) for treatment of benign prostatic hyperplasia (BPH) in older patients and those who are poor surgical candidates. In order to achieve the goals of increased tissue removal volume (i.e., "ablation" in the engineering sense) and reduced collateral thermal damage during the PVP green light treatment, a two dimensional computational model for laser tissue ablation based on available parameters in the literature has been developed and compared to experiments. The model is based on the control volume finite difference and the enthalpy method with a mechanistically defined energy necessary to ablate (i.e., physically remove) a volume of tissue (i.e., energy of ablation E(ab)). The model was able to capture the general trends experimentally observed in terms of ablation and coagulation areas, their ratio (therapeutic index (TI)), and the ablation rate (AR) (mm(3)/s). The model and experiment were in good agreement at a smaller working distance (WD) (distance from the tissue in mm) and a larger scanning speed (SS) (laser scan speed in mm/s). However, the model and experiment deviated somewhat with a larger WD and a smaller SS; this is most likely due to optical shielding and heat diffusion in the laser scanning direction, which are neglected in the model. This model is a useful first step in the mechanistic prediction of PVP based BPH laser tissue ablation. Future modeling efforts should focus on optical shielding, heat diffusion in the laser scanning direction (i.e., including 3D effects), convective heat losses at the tissue boundary, and the dynamic optical, thermal, and coagulation properties of BPH tissue.

  9. Laser ablation-laser induced breakdown spectroscopy for the measurement of total elemental concentration in soils.

    Science.gov (United States)

    Pareja, Jhon; López, Sebastian; Jaramillo, Daniel; Hahn, David W; Molina, Alejandro

    2013-04-10

    The performances of traditional laser-induced breakdown spectroscopy (LIBS) and laser ablation-LIBS (LA-LIBS) were compared by quantifying the total elemental concentration of potassium in highly heterogeneous solid samples, namely soils. Calibration curves for a set of fifteen samples with a wide range of potassium concentrations were generated. The LA-LIBS approach produced a superior linear response different than the traditional LIBS scheme. The analytical response of LA-LIBS was tested with a large set of different soil samples for the quantification of the total concentration of Fe, Mn, Mg, Ca, Na, and K. Results showed an acceptable linear response for Ca, Fe, Mg, and K while poor signal responses were found for Na and Mn. Signs of remaining matrix effects for the LA-LIBS approach in the case of soil analysis were found and discussed. Finally, some improvements and possibilities for future studies toward quantitative soil analysis with the LA-LIBS technique are suggested.

  10. Ultra-short laser pulse ablation using shear-force feedback: Femtosecond laser induced breakdown spectroscopy feasibility study

    International Nuclear Information System (INIS)

    Samek, Ota; Kurowski, Andre; Kittel, Silke; Kukhlevsky, Sergei; Hergenroeder, Roland

    2005-01-01

    This work reports on a feasibility study of proximity ablation using femtosecond pulses. Ultra-short pulses were launched to a bare tapered optical fiber and delivered to the sample. The tip-sample distance was controlled by means of shear-force feedback. Consequently, ablation craters with submicrometer dimensions were obtained. Potential analytical applications for Laser Induced Breakdown Spectroscopy (LIBS) technique, such as e.g. inclusions in steel or bio cells, are suggested

  11. UV laser ablation of intraocular lenses: SEM and AFM microscopy examination of the biomaterial surface

    International Nuclear Information System (INIS)

    Spyratou, E.; Asproudis, I.; Tsoutsi, D.; Bacharis, C.; Moutsouris, K.; Makropoulou, M.; Serafetinides, A.A.

    2010-01-01

    Several new materials and patterns are studied for the formation and etching of intraocular lenses (IOLs), in order to improve their optical properties, to reduce the diffractive aberrations and to decrease the incidence of posterior capsular opacification. The aim of this study is to investigate the use of UV (λ = 266 nm) laser pulses to ablate the intraocular lenses materials, and thus to provide an alternative to conventional surface shaping techniques for IOLs fabrication. Ablation experiments were conducted using various polymer substrates of hydrophobic acrylic IOLs and PMMA IOLs. We investigated the ablation efficiency and the morphology of the ablated area by imaging the surface modification with atomic force microscopy (AFM) and scanning electron microscopy (SEM). The morphological appearance of IOL samples reveals the effect of a photochemical and photothermal ablation mechanism.

  12. Integrated polymer polarization rotator based on tilted laser ablation

    Science.gov (United States)

    Poulopoulos, Giannis; Kalavrouziotis, Dimitrios; Missinne, Jeroen; Bosman, Erwin; Van Steenberge, Geert; Apostolopoulos, Dimitrios; Avramopoulos, Hercules

    2017-02-01

    sidewalls, employing the tilted laser ablation technology, currently available at CMST. Therefore, the aforementioned simulation steps adhere fully to the respective design rules, taking into account the anticipated fabrication variations

  13. Synthesis and characterization of a novel laser ablation sensitive triazene incorporated epoxy resin

    KAUST Repository

    Patole, Archana S.

    2014-01-01

    New triazene monomer was synthesized and further employed as a crosslinking agent partner with epoxy matrix using ethyl methyl imidazole as a curing agent in order to investigate the effect of triazene moieties on polymeric properties for laser ablation application. The synthesized triazene monomer was characterized by analytical and spectroscopic methods, while the surface morphology of resist after laser ablation was visualized by optical laser scanning images and scanning electron microscopy. Thermogravimetrical investigations indicate the loss of nitrogen being the initial thermal decomposition step and exhibit sufficient stabilities for the requirements for laser ablation application. Fourier transform infra-red, nuclear magnetic resonance, and gas chromatography analyses showed the successful synthesis of triazene. The ablation results from the optical laser scanning images revealed that the etching depth could be controlled by varying the concentration of triazene monomer in the formulation of epoxy. The shear strength analysis revealed that that the shear strength increased with increasing the amount of triazene in the formulation of direct ablation sensitive resist. © 2014 The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht.

  14. Heat generation caused by ablation of dental hard tissues with an ultrashort pulse laser (USPL) system.

    Science.gov (United States)

    Braun, Andreas; Krillke, Raphael Franz; Frentzen, Matthias; Bourauel, Christoph; Stark, Helmut; Schelle, Florian

    2015-02-01

    Heat generation during the removal of dental hard tissues may lead to a temperature increase and cause painful sensations or damage dental tissues. The aim of this study was to assess heat generation in dental hard tissues following laser ablation using an ultrashort pulse laser (USPL) system. A total of 85 specimens of dental hard tissues were used, comprising 45 specimens of human dentine evaluating a thickness of 1, 2, and 3 mm (15 samples each) and 40 specimens of human enamel with a thickness of 1 and 2 mm (20 samples each). Ablation was performed with an Nd:YVO4 laser at 1,064 nm, a pulse duration of 9 ps, and a repetition rate of 500 kHz with an average output power of 6 W. Specimens were irradiated for 0.8 s. Employing a scanner system, rectangular cavities of 1-mm edge length were generated. A temperature sensor was placed at the back of the specimens, recording the temperature during the ablation process. All measurements were made employing a heat-conductive paste without any additional cooling or spray. Heat generation during laser ablation depended on the dental hard tissue (enamel or dentine) and the thickness of the respective tissue (p dental hard tissues, heat generation has to be considered. Especially during laser ablation next to pulpal tissues, painful sensations and potential thermal injury of pulp tissue might occur.

  15. Ablative fractional laser enhances MAL-induced PpIX accumulation

    DEFF Research Database (Denmark)

    Haak, C S; Christiansen, K; Erlendsson, Andrés M

    2016-01-01

    BACKGROUND AND OBJECTIVES: Pretreatment of skin with ablative fractional laser enhances accumulation of topical provided photosensitizer, but essential information is lacking on the interaction between laser channel densities and pharmacokinetics. Hence our objectives were to investigate how...... protoporphyrin accumulation was affected by laser densities, incubation time and drug concentration. METHODS: We conducted the study on the back of healthy male volunteers (n=11). Test areas were pretreated with 2940nm ablative fractional Er:YAG laser, 11.2mJ per laser channel using densities of 1, 2, 5, 10...... incubation. The individual fluorescence intensity reached from the highest density (15%) and longest MAL 160mg/g incubation time (180min) was selected as reference (100%) for other interventional measurements. RESULTS: A low laser density of 1% markedly enhanced fluorescence intensities from 34% to 75% (no...

  16. Numerical analysis of laser ablation using the axisymmetric two-temperature model

    Science.gov (United States)

    Dziatkiewicz, Jolanta; Majchrzak, Ewa

    2018-01-01

    Laser ablation of the axisymmetric micro-domain is analyzed. To describe the thermal processes occurring in the micro-domain the two-temperature hyperbolic model supplemented by the boundary and initial conditions is used. This model takes into account the phase changes of material (solid-liquid and liquid-vapour) and the ablation process. At the stage of numerical computations the finite difference method with staggered grid is used. In the final part the results of computations are shown.

  17. Evaluation of the efficacy of excimer laser ablation of cross-linked porcine cornea.

    Directory of Open Access Journals (Sweden)

    Shihao Chen

    Full Text Available BACKGROUND: Combination of riboflavin/UVA cross-linking (CXL and excimer laser ablation is a promising therapy for treating corneal ectasia. The cornea is strengthened by cross-linking, while the irregular astigmatism is reduced by laser ablation. This study aims to compare the efficacy of excimer laser ablation on porcine corneas with and without cross-linking. METHODS AND FINDINGS: The porcine cornea was de-epithelialized and treated with 0.1% riboflavin solution for 30 minutes. A half of the cornea was exposed to UVA-radiation for another 30 minutes while the controlled half of the cornea was protected from the UVA using a metal shield. Photo therapeutic keratectomy (PTK was then performed on the central cornea. Corneal thickness of 5 paired locations on the horizontal line, ± 0.5, ± 1.0, ± 1.5, ± 2.0, and ± 2.5 mm from the central spot, were measured using optical coherence tomography prior to and after PTK. The ablation depth was then determined by the corneal thickness. There was a 9% difference (P<0.001 in the overall ablation depth between the CXL-half corneas (158 ± 22 µm and the control-half corneas (174 ± 26 µm. The ablation depths of all 5 correspondent locations on the CXL-half were significantly smaller (P<0.001. CONCLUSION: The efficacy of the laser ablation seems to be lower in cross-linked cornea. Current ablation algorithms may need to be modified for cross-linked corneas.

  18. XPS investigations on the UV-laser ablation mechanism of poly(ether imide)

    Energy Technology Data Exchange (ETDEWEB)

    Wambach, J.; Kunz, T.; Schnyder, B.; Koetz, R.; Wokaun, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    UV-Laser ablated samples of poly(ether imide) [Kapton{sup TM}] were studied with small-spot XPS. Applying fluences above the threshold level (0.167 J/cm{sup 2}) resulted in the expected behaviour of a decline of both nitrogen and oxygen. Below the threshold level a hint for an altered ablation mechanism was found. (author) 1 fig., 5 refs.

  19. Ablation of organic polymers by 46.9-nm-laser radiation

    Czech Academy of Sciences Publication Activity Database

    Juha, Libor; Bittner, Michal; Chvostová, Dagmar; Krása, Josef; Präg R., Ansgar; Ullschmied, Jiří; Pientka, Zbyněk; Krzywinski, J.; Wawro, A.; Grisham, M. E.; Menoni, C.S.; Rocca, J.J.; Otčenášek, Zdeněk; Pelka, B.; Vaschenko, G. O.

    2005-01-01

    Roč. 86, č. 3 (2005), 034109/1-034109/3 ISSN 0003-6951 R&D Projects: GA MŠk(CZ) 1P04LA235; GA MŠk(CZ) LN00A100 Institutional research plan: CEZ:AV0Z10100523 Keywords : ablation * XUV laser * capillary discharge laser Subject RIV: BH - Optics, Masers, Lasers Impact factor: 4.127, year: 2005

  20. XUV-laser induced ablation of PMMA with nano-, pico-, and femtosecond pulses

    Czech Academy of Sciences Publication Activity Database

    Juha, Libor; Bittner, Michal; Chvostová, Dagmar; Létal, V.; Krása, Josef; Otčenášek, Zdeněk; Kozlová, Michaela; Polan, Jiří; Präg R., Ansgar; Rus, Bedřich; Stupka, Michal; Krzywinski, J.; Andrejczuk, A.; Pelka, J. B.; Sobierajski, R.; Ryc, L.; Feldhaus, J.; Boody, F. P.; Grisham, M. E.; Vaschenko, G. O.; Menoni, C.S.; Rocca, J.J.

    144-147, - (2005), s. 929-932 ISSN 0368-2048 R&D Projects: GA MŠk(CZ) 1P04LA235; GA MŠk(CZ) LN00A100 Institutional research plan: CEZ:AV0Z10100523 Keywords : XUV lasers * soft x-ray lasers * ablation * pulse duration effects * wavelength effects * poly(methyl methacrylate) * PMMA Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.183, year: 2005

  1. Identification of photoacoustic transients during pulsed laser ablation of the human temporal bone: an experimental model.

    Science.gov (United States)

    Wong, B J; Dickinson, M R; Berns, M W; Neev, J

    1996-12-01

    Laser ablation of hard tissues during neurotologic operations has been accomplished with continuous-wave (CW) lasers in the visible and midinfrared spectrum. The mechanism of ablation at these wavelengths is secondary to photothermal-induced tissue destruction. As a result, significant thermal damage to surrounding tissue may occur. Pulsed ultraviolet (UV) lasers have been suggested as an alternative to the argon, KTP-532, and CO2 lasers currently used in clinical practice. The pulse length of Excimer lasers are considerably shorter than the thermal diffusion time of bone tissue, and as a consequence thermal injury is minimal. This makes pulsed lasers an attractive tool for tissue ablation in the ear: in essence a "cold knife." However, the short pulse width of Excimer lasers (typically 10-150 ns) can create large thermoelastic stresses in the ablation specimen. This study identifies the presence of these photoacoustic waves during the Excimer laser treatment of the cadaveric human temporal bone. A XeCl (lambda = 308 nm, tau p = 12 ns) excimer laser was used to ablate hard tissue surrounding the oval window and facial ridge with energies of 75, 45, 25, and 12 mJ/pulse. Spot size was estimated to be 0.5 mm2. Custom high-frequency polyvinyldifluoride (PVDF) piezoelectric film transducers were fabricated and attached to the promontory, round window niche, and facial ridges. The signals were amplified using a low-noise preamplifier and recorded on a digitizing oscilloscope. Photoacoustic waves were clearly identified. Notably, large acoustic waves were measured on the promontory and on both sides of the facial ridge. The implications and clinical relevance of these findings is discussed and compared to findings obtained from a model system.

  2. Optical feedback-induced light modulation for fiber-based laser ablation.

    Science.gov (United States)

    Kang, Hyun Wook

    2014-11-01

    Optical fibers have been used as a minimally invasive tool in various medical fields. However, due to excessive heat accumulation, the distal end of a fiber often suffers from severe melting or devitrification, leading to the eventual fiber failure during laser treatment. In order to minimize thermal damage at the fiber tip, an optical feedback sensor was developed and tested ex vivo. Porcine kidney tissue was used to evaluate the feasibility of optical feedback in terms of signal activation, ablation performance, and light transmission. Testing various signal thresholds demonstrated that 3 V was relatively appropriate to trigger the feedback sensor and to prevent the fiber deterioration during kidney tissue ablation. Based upon the development of temporal signal signatures, full contact mode rapidly activated the optical feedback sensor possibly due to heat accumulation. Modulated light delivery induced by optical feedback diminished ablation efficiency by 30% in comparison with no feedback case. However, long-term transmission results validated that laser ablation assisted with optical feedback was able to almost consistently sustain light delivery to the tissue as well as ablation efficiency. Therefore, an optical feedback sensor can be a feasible tool to protect optical fiber tips by minimizing debris contamination and delaying thermal damage process and to ensure more efficient and safer laser-induced tissue ablation.

  3. Surface microstructure and chemistry of polyimide by single pulse ablation of picosecond laser

    Science.gov (United States)

    Du, Qifeng; Chen, Ting; Liu, Jianguo; Zeng, Xiaoyan

    2018-03-01

    Polyimide (PI) surface was ablated by the single pulse of picosecond laser, and the effects of laser wavelength (λ= 355 nm and 1064 nm) and fluence on surface microstructure and chemistry were explored. Scanning electron microscopy (SEM) analysis found that different surface microstructures, i.e., the concave of concentric ring and the convex of porous circular disk, were generated by 355 nm and 1064 nm picosecond laser ablation, respectively. X-ray photoelectron spectroscopy (XPS) characterization indicated that due to the high peak energy density of picosecond laser, oxygen and nitrogen from the ambient were incorporated into the PI surface mainly in the form of Cdbnd O and Csbnd Nsbnd C groups. Thus, both of the O/C and N/C atomic content ratios increased, but the increase caused by 1064 nm wavelength laser was larger. It inferred that the differences of PI surface microstructures and chemistry resulted from different laser parameters were related to different laser-matter interaction effects. For 355 nm picosecond laser, no obvious thermal features were observed and the probable ablation process of PI was mainly governed by photochemical effect; while for 1064 nm picosecond laser, obvious thermal feature appeared and photothermal effect was thought to be dominant.

  4. Endovenous Laser Ablation as a Treatment for Postsurgical Recurrent Saphenous Insufficiency

    International Nuclear Information System (INIS)

    Anchala, Praveen R.; Wickman, Christopher; Chen, Richard; Faundeen, Tonya; Pearce, William; Narducy, Lisa; Resnick, Scott A.

    2010-01-01

    The purpose of this study was to investigate the safety and efficacy of endovenous laser ablation as a treatment for recurrent symptomatic saphenous insufficiency occurring after saphenous vein ligation and stripping. A single-center retrospective review of patients who received endovenous laser ablation as a treatment for recurrent symptomatic saphenous insufficiency after ligation and stripping between November 2003 and October 2006 was performed. Fifty-six insufficient saphenous systems were identified in 38 patients. Follow-up consisted of a clinical examination in all patients as well as selective lower-extremity duplex ultrasound as clinically indicated. All 38 patients demonstrated complete closure of the insufficient saphenous vein by clinical examination and/or duplex ultrasound evaluation. Preoperative symptoms resolved after treatment in all 38 patients. No major complications were identified. Endovenous laser ablation of recurrent symptomatic saphenous venous insufficiency is a safe and effective treatment in patients who develop recurrent symptoms after saphenous vein ligation and stripping.

  5. Laser ablation of metal into liquid: near critical point phenomena and hydrodynamic instability

    Science.gov (United States)

    Inogamov, Nail; Zhakhovsky, Vasily; Khokhlov, Viktor

    2017-06-01

    Laser ablation of metal in contact with liquid differs much from ablation into vacuum. In spite of importance of this kind of laser-matter interaction (e.g., for nanoparticles production), the involved processes are still poorly understood. We show that to produce nanoparticles the laser absorbed energy should overcome the ablation threshold into vacuum by a few times. Thus the required temperatures in the heat-affected zone increase above a critical temperature. The flow of the substances, including propagation of a strong shock in liquid and a rarefaction wave inside the metal target, is analyzed. We demonstrate that the contact between metal and liquid, both being in their supercritical states, is hydrodynamically unstable. The instability is of the Rayleigh-Taylor type. Dynamics of the instability is important for separation of melt droplets which are frozen up to solid nanoparticles later.

  6. Synthesis of molybdenum oxide-titanium dioxide nanocomposites with ultrashort laser ablation in water.

    Science.gov (United States)

    Khan, Abdul Qayyum; Yuan, Shuai; Niu, Sheng; Zheng, Lijuan; Li, Wenxue; Zeng, Heping

    2017-06-12

    Nanocomposites of Molybdenum oxide (MoO 3 ) and Titanium dioxide (TiO 2 ) were synthesized with femtosecond laser ablation of the pelleted powder in water. The pressing with Cold Isostatic press (CIP) provides facile method for pelletization of the oxides mixture. With this method the nanocomposites can be synthesized without replacement of the target during laser ablation. After laser ablation in water the stable MoO 3 -TiO 2 nanocomposites were synthesized. The morphology of the synthesized nanocomposites was investigated with transmission electron microscopy. While the band gap modifications of the synthesized nanocomposites were witnessed with UV-Visible diffuse reflectance spectroscopy analysis. Besides, the generated nanocomposites were used for photovoltaic and photocatalytic applications. The nanocomposites exhibit significant improvement in the rate of photo conversion and photodegradation as well.

  7. Synthesis of higher diamondoids by pulsed laser ablation plasmas in supercritical CO2

    Science.gov (United States)

    Nakahara, Sho; Stauss, Sven; Kato, Toru; Sasaki, Takehiko; Terashima, Kazuo

    2011-06-01

    Pulsed laser ablation (wavelength 532 nm; fluence 18 J/cm2; pulse width 7 ns; repetition rate 10 Hz) of highly oriented pyrolytic graphite was conducted in adamantane-dissolved supercritical CO2 with and without cyclohexane as a cosolvent. Micro-Raman spectroscopy of the products revealed the presence of hydrocarbons possessing sp3-hybridized carbons similar to diamond structures. The synthesis of diamantane and other possible diamondoids consisting of up to 12 cages was confirmed by gas chromatography-mass spectrometry. Furthermore, gas chromatography-mass spectrometry measurements of samples before and after pyrolysis treatment indicate the synthesis of the most compact decamantane, namely, superadamantane. It is thought that oxidant species originating from CO2 during pulsed laser ablation might lead to the selective dissociation of C-H bonds, enabling the synthesis of low H/C ratio molecules. Therefore, laser ablation in supercritical CO2 is proposed as a practical method for synthesizing diamondoids.

  8. Studies on perovskite film ablation and scribing with ns-, ps- and fs-laser pulses

    Science.gov (United States)

    Bayer, Lukas; Ye, Xinyuan; Lorenz, Pierre; Zimmer, Klaus

    2017-10-01

    Hybrid organic-inorganic perovskites attract much attention due to their exceptional optoelectronic properties, in particular for photovoltaic (PV) applications. The accurate, high-speed and reliable patterning of the PV films is required for perovskite solar modules fabrication. Laser scribing provides these characteristics needed for industrial fabrication processes. In this work, the laser ablation and scribing of perovskite layers (CH3NH3PbI3: MAPbI3) with different laser sources (ns-, ps-, fs-laser pulses with wavelengths of 248 nm to 2.5 µm) were systematically investigated. The perovskite material was irradiated from both the film side and the substrate (rear side) side to study and compare the particular processes. The patterning results of the perovskite film can be classified into (1) regular laser ablation, (2) thin-film delamination lift-off process, and (3) lift-off with thermal modifications. A particular process, the localised lift-off of single grains from the perovskite film, has been observed and is discussed in relation to the thin-film lift-off process. Ablation and ablation-related mechanisms provide good conditions for laser scribing of the perovskite layer required for module interconnection via P2.

  9. Interstitial laser-induced thermotherapy of the lung: evaluation of the influence of ablation continuity on ablation size in a swine model.

    Science.gov (United States)

    Schoellnast, Helmut; Monette, Sebastien; Ezell, Paula C; Keene, Andrew; Quehenberger, Franz; Erinjeri, Joseph P; Solomon, Stephen B

    2013-02-22

    The purpose of this study was to assess the relationship between size and the continuity of energy application in interstitial laser-induced thermotherapy. Percutaneous computed tomography-guided laser ablation (30 W, 600 nm diode) of the lung was performed in 7 Yorkshire pigs; a total of 42 ablation zones were created. Twenty ablations were performed using a continuous cycle of 2 min (protocol A) and 22 ablations were performed using 4 intermittent cycles with a duration of 1 min for each cycle interrupted by a 10-s stop between the cycles (protocol B). The lung was harvested immediately after euthanasia for gross pathology and histopathologic evaluation. Statistical analysis was performed using the Student t test and the Spearman correlation coefficient. Laser ablation resulted in complete necrosis of variable size of lung. The mean ablation zone dimensions (±SD) were 1.9 (±0.4) cm × 1.4 (±0.3) cm for protocol A and 2.2 (±0.5) cm × 1.4 (±0.4) cm for protocol B. The size of the necrosis is not significantly different when comparing a continuous 2-min ablation to a 4-cycle intermittent ablation for 1 min each cycle interrupted by a 10-s stop between the cycles (P = 0.98 and 0.53, respectively).

  10. An x-ray probe of nickel nanoparticles generated by laser ablation

    Science.gov (United States)

    Lehmann, C. S.; Doumy, G.; Southworth, S. H.; March, A. M.; Dichiara, A. D.; Gao, Y.; Kanter, E. P.; Krässig, B.; Moonshiram, D.; Young, L.; Chapman, K. W.; Chupas, P. J.

    2014-05-01

    A plume of nickel atoms and nanoparticles can be generated by an intense laser pulse hitting a solid nickel surface. We set up a Ni ablation source in a vacuum chamber on an x-ray beamline at the Advanced Photon Source and used x-ray absorption, x-ray emission, and ion spectroscopies to probe the ablation plume at x-ray energies above the Ni K-edge at 8.33 keV. The laser and x-ray pulses were overlapped in time and space with variable delay to measure the time evolution of the ablation plume. Measurements of the charge states produced by x-ray absorption were not possible due to the intense prompt ions ejected in the ablation process. However, Ni K α x-ray emission was measured as functions of laser fluence and pump-probe delay. The fluorescence yield was also used to record the near-edge x-ray absorption spectrum of the nanoparticles in the plume. The nanoparticles were collected and their diameters were determined to be ~9 nm from x-ray scattering pair-distribution-function measurements. The experiments demonstrate the use of x-ray techniques to characterize laser ablation processes. Work supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, US Dept of Energy, Contract DE-AC02-06CH11357.

  11. Investigations of morphological features of picosecond dual-wavelength laser ablation of stainless steel

    Science.gov (United States)

    Zhao, Wanqin; Wang, Wenjun; Mei, Xuesong; Jiang, Gedong; Liu, Bin

    2014-06-01

    Investigations on the morphological features of holes and grooves ablated on the surface of stainless steel using the picosecond dual-wavelength laser system with different powers combinations are presented based on the scarce researches on morphology of dual-wavelength laser ablation. The experimental results show the profiles of holes ablated by the visible beam appear V-shaped while those for the near-infrared have large openings and display U-shaped, which are independent of the ablation mechanism of ultrafast laser. For the dual-wavelength beam (a combination of visible beam and near-infrared), the holes resemble sunflower-like structures and have smoother ring patterns on the bottom. In general, the holes ablated by the dual-wavelength beam appear to have much flatter bottoms, linearly sloped side-walls and spinodal structures between the bottoms of the holes and the side-walls. Furthermore, through judiciously combining the powers of the dual-wavelength beam, high-quality grooves could be obtained with a flat worm-like structure at the bottom surface and less resolidified melt ejection edges. This study provides insight into optimizing ultrafast laser micromachining in order to obtain desired morphology.

  12. Tissue ablation and gas formation of two excimer laser systems: an in vitro evaluation on porcine aorta

    NARCIS (Netherlands)

    Appelman, Y. E.; Piek, J. J.; Verhoofstad, G. G.; Gijsbers, G. H.; van Gemert, M. J.

    1996-01-01

    BACKGROUND and The relationship between tissue ablation volume and the formation of insoluble gas of the currently available excimer laser systems is unknown. This aspect was evaluated in two excimer laser systems. STUDY DESIGN/MATERIALS and We measured tissue ablation volume and gas production of

  13. Investigations of the damage mechanisms during ultrashort pulse laser ablation of dental tissue

    Science.gov (United States)

    Domke, Matthias; Wick, Sebastian; Laible, Maike; Rapp, Stephan; Kuznetsova, Julia; Homann, Christian; Huber, Heinz P.; Sroka, Ronald

    2015-07-01

    Several investigations of dental tissue ablation with ultrashort pulsed lasers suggest that these lasers enable precise and selective material removal and reduce the formation of micro cracks and thermal effects, when compared to ns-pulses. In this study, two damage mechanisms are presented occurring during ablation of dentin using a laser emitting pulses of a duration of 380 fs at a wavelength of 1040 nm. First, it was found that nano cracks appear around the craters after single fs-pulse ablation. These cracks are directed to the crater and cross the dentinal tubules. Transient investigation of the single fs-pulse ablation process by pump-probe microscopy suggest that the driving mechanism could be a pressure wave that is released after stress confinement. Second, squared ablation holes were created by moving the laser focus at scan speeds between 0.5 mm/s and 2.0 m/s and fluences up to 14 J/cm2. It was found that deep cracks appear at the edges of the squared holes, if the scan speed is about 0.5 m/s. The fluence has only a minor impact on the crack formation. The crack propagation was investigated in the depth using x-ray micro tomography and optical coherence tomography. It was found that these cracks appear in the depth down to the dental pulp. These findings suggest that fast scanning of the laser beam is the key for damage free processing using ultrashort pulse lasers. Then, ablation rates of about 2.5 - 3.5 mm3/min/W can be achieved in dentine with pulse durations of 380 fs.

  14. Influence of external cooling on the femtosecond laser ablation of dentin.

    Science.gov (United States)

    Le, Q T; Vilar, R; Bertrand, C

    2017-12-01

    In the present work, the influence of external cooling on the temperature rise in the tooth pulpal chamber during femtosecond laser ablation was investigated. The influence of the cooling method on the morphology and constitution of the laser-treated surfaces was studied as well. The ablation experiments were performed on dentin specimens using an Yb:KYW chirped-pulse-regenerative amplification laser system (560 fs, 1030 nm). Cavities were created by scanning the specimens at a velocity of 5 mm/s while pulsing the stationary laser beam at 1 kHz and with fluences in the range of 2-14 J/cm 2 . The experiments were performed in air and with surface cooling by a lateral air jet and by a combination of an air jet and water irrigation. The temperature in the pulpal chamber of the tooth was measured during the laser experiments. The ablation surfaces were characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The temperature rise reached 17.5 °C for the treatments performed with 14 J/cm 2 and without cooling, which was reduced to 10.8 ± 1.0 and 6.6 ± 2.3 °C with forced air cooling and water cooling, respectively, without significant reduction of the ablation rate. The ablation surfaces were covered by ablation debris and resolidified droplets containing mainly amorphous calcium phosphate, but the amount of redeposited debris was much lower for the water-cooled specimens. The redeposited debris could be removed by ultrasonication, revealing that the structure and constitution of the tissue remained essentially unaltered. The present results show that water cooling is mandatory for the femtosecond laser treatment of dentin, in particular, when high fluences and high pulse repetition rates are used to achieve high material removal rates.

  15. Translational medicine in the field of ablative fractional laser (AFXL)-assisted drug delivery

    DEFF Research Database (Denmark)

    Haedersdal, Merete; Erlendsson, Andrés M; Paasch, Uwe

    2016-01-01

    Ablative fractional lasers enhance uptake of topical therapeutics and the concept of fractional laser-assisted drug delivery has now been taken into clinical practice. Objectives We systematically reviewed preclinical data and clinical evidence for fractional lasers to enhance drug uptake...... level of evidence was reached for actinic keratoses treated with methylaminolevulinate for photodynamic therapy (level IB, 5 randomized controlled trials), substantiating superior and long-lasting efficacy versus conventional photodynamic therapy. No adverse events were reported, but ablative fractional...... laser-assisted drug delivery implies risks of systemic drug absorption, especially when performed over large skin areas. Conclusions Fractional laser-assisted drug delivery is beneficial in enhancing preclinical and clinical outcomes for certain skin conditions....

  16. Mass spectroscopic analysis of a plume induced by laser ablation of pyrolytic boron nitride

    CERN Document Server

    Chae, H B; Lee, I H; Park, S M

    1998-01-01

    The laser ablation of a pyrolytic boron nitride (pBN) target was investigated by time-of- flight quadrupole mass spectroscopy. According to the laser-correlated ion mass spectra, B sup + and B sub 2 sup + ions were produced, but neither N sup + , N sub 2 sup + , or BN sup + ions were observed at laser fluences below 1 J/cm sup 2. Instead, neutral N sub 2 molecules were found to be formed. The mean velocities and kinetic energies of the B sup + ions were obtained by time-of-flight analysis. Also, reactive laser ablation under a N sub 2 atmosphere was attempted by using a pulsed valve synchronized with the laser pulse.

  17. Short-pulse laser ablation of solids: From phase explosion to fragmentation

    International Nuclear Information System (INIS)

    Lorazo, Patrick; Lewis, Laurent J.; Meunier, Michel

    2003-01-01

    The mechanisms of laser ablation in silicon are investigated close to the threshold energy for pulse durations of 500 fs and 50 ps. This is achieved using a unique model coupling carrier and atom dynamics within a unified Monte Carlo and molecular-dynamics scheme. Under femtosecond laser irradiation, isochoric heating and rapid adiabatic expansion of the material provide a natural pathway to phase explosion. This is not observed under slower, nonadiabatic cooling with picosecond pulses where fragmentation of the hot metallic fluid is the only relevant ablation mechanism

  18. Spot size and pulse number dependence of femtosecond laser ablation thresholds of silicon and stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Armbruster, Oskar; Naghilou, Aida [University of Vienna, Department of Physical Chemistry, Währinger Straße 42, A-1090 Vienna (Austria); Kitzler, Markus [TU Wien, Photonics Institute, Gusshausstraße 27-29, A-1040 Vienna (Austria); Kautek, Wolfgang, E-mail: wolfgang.kautek@univie.ac.at [University of Vienna, Department of Physical Chemistry, Währinger Straße 42, A-1090 Vienna (Austria)

    2017-02-28

    Highlights: • Influence of laser spot size and pulse number on the ablation of solids. • An extended defect model describes the dependence of the threshold fluence on the basis of high and low density defects. • Successfully applied to silicon and stainless steel. - Abstract: Laser spot size and pulse number are two major parameters influencing the ablation of solids. The extended defect model describes the dependence of the threshold fluence on the basis of high and low density defects. This model was successfully applied to silicon and stainless steel. It is demonstrated that heat accumulation cannot describe the experimental results.

  19. Study on high-speed deep etching of GaN film by UV laser ablation

    Science.gov (United States)

    Zhang, J.; Sugioka, K.; Wada, S.; Tashiro, H.; Midorikawa, K.

    1998-06-01

    High-speed deep etching of GaN thin films by UV (266 nm) laser ablation followed by a treatment in HCl solution, was achieved. The etch rate was as high as 50 nm/pulse. Scanning electron microscopy and scanning probe microscopy measurement results indicate that the surface of the etched films was structurally well-defined and cleanly patterned. Micro-photoluminescence measurements of ablated samples revealed no severe damage to the optical properties or the crystal structure. In addition, coupling with VUV (133-184 nm) laser beams, the etch quality of GaN was markedly improved. The etch rate was 55 nm/pulse

  20. Structure and Properties of Nanocrystalline Iron Oxide Powder Prepared by the Method of Pulsed Laser Ablation

    Science.gov (United States)

    Svetlichnyi, V. A.; Shabalina, A. V.; Lapin, I. N.

    2017-04-01

    Colloidal solution of iron oxide nanoparticles is synthesized by nanosecond pulsed laser ablation (Nd:YAG laser, 1064 nm, 7 ns, and 180 mJ) of a metallic iron target in water, and nanocrystalline powder is prepared from this solution by vacuum drying. A composition and structure of the material obtained are investigated by methods of electron microscopy, x-ray diffraction, and optical spectroscopy. It is established that oxide particles with average size of about 5 nm and Fe3O4 magnetite structure are mainly formed during ablation. Preliminary investigation of magnetic properties of the prepared nanoparticle powders shows that they can be in ferromagnetic and/or superparamagnetic states.

  1. Experimental study of laser ablation as sample introduction technique for inductively coupled plasma-mass spectrometry

    International Nuclear Information System (INIS)

    Van Winckel, S.

    2001-01-01

    The contribution consists of an abstract of a PhD thesis. In the PhD study, several complementary applications of laser-ablation were investigated in order to characterise experimentally laser ablation (LA) as a sample introduction technique for ICP-MS. Three applications of LA as a sample introduction technique are discussed: (1) the microchemical analysis of the patina of weathered marble; (2) the possibility to measure isotope ratios (in particular Pb isotope ratios in archaeological bronze artefacts); and (3) the determination of Si in Al as part of a dosimetric study of the BR2 reactor vessel

  2. Coagulative and ablative characteristics of a novel diode laser system (1470nm) for endonasal applications

    Science.gov (United States)

    Betz, C. S.; Havel, M.; Janda, P.; Leunig, A.; Sroka, R.

    2008-02-01

    Introduction: Being practical, efficient and inexpensive, fibre guided diode laser systems are preferable over others for endonasal applications. A new medical 1470 nm diode laser system is expected to offer good ablative and coagulative tissue effects. Methods: The new 1470 nm diode laser system was compared to a conventional 940 nm system with regards to laser tissue effects (ablation, coagulation, carbonization zones) in an ex vivo setup using fresh liver and muscle tissue. The laser fibres were fixed to a computer controlled stepper motor, and the light was applied using comparable power settings and a reproducible procedure under constant conditions. Clinical efficacy and postoperative morbidity was evaluated in two groups of 10 patients undergoing laser coagulation therapy of hyperplastic nasal turbinates. Results: In the experimental setup, the 1470 nm laser diode system proved to be more efficient in inducing tissue effects with an energy factor of 2-3 for highly perfused hepatic tissue to 30 for muscular tissue. In the clinical case series, the higher efficacy of the 1470 nm diode laser system led to reduced energy settings as compared to the conventional system with comparable clinical results. Postoperative crusting was less pronounced in the 1470 nm laser group. Conclusion: The 1470 nm diode laser system offers a highly efficient alternative to conventional diode laser systems for the coagulation of hyperplastic nasal turbinates. According to the experimental results it can be furthermore expected that it disposes of an excellent surgical potential with regards to its cutting abilities.

  3. Focal Laser Ablation of Prostate Cancer: Feasibility of Magnetic Resonance Imaging-Ultrasound Fusion for Guidance.

    Science.gov (United States)

    Natarajan, Shyam; Jones, Tonye A; Priester, Alan M; Geoghegan, Rory; Lieu, Patricia; Delfin, Merdie; Felker, Ely; Margolis, Daniel J A; Sisk, Anthony; Pantuck, Allan; Grundfest, Warren; Marks, Leonard S

    2017-10-01

    Focal laser ablation is a potential treatment in some men with prostate cancer. Currently focal laser ablation is performed by radiologists in a magnetic resonance imaging unit (in bore). We evaluated the safety and feasibility of performing focal laser ablation in a urology clinic (out of bore) using magnetic resonance imaging-ultrasound fusion for guidance. A total of 11 men with intermediate risk prostate cancer were enrolled in this prospective, institutional review board approved pilot study. Magnetic resonance imaging-ultrasound fusion was used to guide laser fibers transrectally into regions of interest harboring intermediate risk prostate cancer. Thermal probes were inserted for real-time monitoring of intraprostatic temperatures during laser activation. Multiparametric magnetic resonance imaging (3 Tesla) was done immediately after treatment and at 6 months along with comprehensive fusion biopsy. Ten of 11 patients were successfully treated while under local anesthesia. Mean procedure time was 95 minutes (range 71 to 105). Posttreatment magnetic resonance imaging revealed a confined zone of nonperfusion in all 10 men. Mean zone volume was 4.3 cc (range 2.1 to 6.0). No CTCAE grade 3 or greater adverse events developed and no changes were observed in urinary or sexual function. At 6 months magnetic resonance imaging-ultrasound fusion biopsy of the treatment site showed no cancer in 3 patients, microfocal Gleason 3 + 3 in another 3 and persistent intermediate risk prostate cancer in 4. Focal laser ablation of prostate cancer appears safe and feasible with the patient under local anesthesia in a urology clinic using magnetic resonance imaging-ultrasound fusion for guidance and thermal probes for monitoring. Further development is necessary to refine out of bore focal laser ablation and additional studies are needed to determine appropriate treatment margins and oncologic efficacy. Copyright © 2017 American Urological Association Education and Research, Inc

  4. REFINED MODEL OF THE OPTICAL SYSTEM FOR SPACE MINI-VEHICLES WITH LASER PROPULSION

    Directory of Open Access Journals (Sweden)

    M. S. Egorov

    2015-09-01

    Full Text Available Simulation results for on-board optical system of a space mini-vehicle with laser propulsion are presented. This system gives the possibility for receiving theremote laser radiation power independently of a system telescope mutual orientation to the vehicle orbiting direction. The on-board optical system is designed with the use of such optical elements as optical hinges and turrets. The system incorporates the optical switch that is a special optical system adapting optically both receiving telescope and laser propulsion engines. Modeling and numerical simulation of the system have been performed with the use of ZEMAX software (Radiant Ltd. The object matter of calculations lied in size definition of system optical elements, requirements to accuracy of their manufacturing and reciprocal adjusting to achieve an efficient radiation energy delivery to laser propulsion engine. Calculations have been performed with account to the limitations on the mini-vehicle mass, its overall dimensions, and radiation threshold density of the optical elements utilized. The requirements to the laser beam quality at the entrance aperture of laser propulsion engine have been considered too. State-of-the-art optical technologies make it possible to manufacture space reflectors made of CO-115M glassceramics with weight-reducing coefficient of 0.72 and the radiation threshold of 5 J/cm2 for the radiation with a 1.064 microns wavelength at 10-20 ns pulse duration. The optimal diameter of a receiving telescope primary mirror has been 0.5 m when a coordinated transmitting telescope diameter is equal to 1 m. This provides the reception of at least 84% of laser energy. The main losses of radiation energy are caused by improper installation of receiving telescope mirrors and by in-process errors arising at manufacturing the telescope mirrors with a parabolic surface. It is shown that requirements to the in-process admissible errors for the on-board optical system elements

  5. Corneal tissue ablation using 6.1 μm quantum cascade laser

    Science.gov (United States)

    Huang, Yong; Kang, Jin U.

    2012-03-01

    High absorption property of tissues in the IR range (λ> 2 μm) results in effective tissue ablation, especially near 3 μm. In the mid-infrared range, wavelengths of 6.1 μm and 6.45 μm fall into the absorption bands of the amide protein groups Amide-I and Amide-II, respectively. They also coincide with the deformation mode of water, which has an absorption peak at 6.1 μm. This coincidence makes 6.1 μm laser a better ablation tool that has promising effectiveness and minimum collateral damages than 3 μm lasers. In this work, we performed bovine corneal ablation test in-vitro using high-power 6.1μm quantum cascade laser (QCL) operated at pulse mode. Quantum cascade laser has the advantages of low cost, compact size and tunable wavelength, which makes it great alternative Mid-IR light source to conventional tunable free-electron lasers (FEL) for medical applications. Preliminary results show that effective corneal stroma craters were achieved with much less collateral damage in corneal tissue that contains less water. Future study will focus on optimizing the control parameters of QCL to attain neat and precise ablation of corneal tissue and development of high peak power QCL.

  6. Controlled Contamination of Epoxy Composites with PDMS and Removal by Laser Ablation

    Science.gov (United States)

    Palmieri, Frank; Ledesma, Rodolfo; Cataldo, Daniel; Lin, Yi; Wohl, Christopher; Gupta, Mool; Connell, John

    2016-01-01

    Surface preparation is critical to the performance of adhesively bonded composites. During manufacturing, minute quantities of mold release compounds are inevitably deposited on faying surfaces and may compromise bond performance. To ensure safety, mechanical fasteners and other crack arrest features must be installed in the bondlines of primary structures, which negates some advantages of adhesively bonded construction. Laser ablation is an automated, repeatable, and scalable process with high potential for the surface preparation of metals and composites in critical applications such as primary airframe structures. In this study, laser ablation is evaluated on composite surfaces for the removal of polydimethylsiloxane (PDMS), a common mold release material. Composite panels were contaminated uniformly with PDMS film thicknesses as low as 6.0 nm as measured by variable angle spectroscopic ellipsometry. Bond performance was assessed by mechanical testing using a 250 F cure, epoxy adhesive and compared with pre-bond surface inspection results. Water contact angle, optically stimulated electron emission, and laser induced breakdown spectroscopy were used to characterize contaminated and laser ablated surfaces. The failure mode obtained from double cantilever beam tests correlated well with surface characterization data. The test results indicated that even low levels of PDMS were not completely removed by laser ablation.

  7. Laser Ablation Surface Preparation of Ti-6A1-4V for Adhesive Bonding

    Science.gov (United States)

    Palmieri, Frank L.; Watson, Kent A.; Morales, Guillermo; Williams, Thomas; Hicks, Robert; Wohl, Christopher J.; Hopkins, John W.; Connell, John W.

    2012-01-01

    Adhesive bonding offers many advantages over mechanical fastening, but requires certification before it can be incorporated in primary structures for commercial aviation without disbond-arrestment features or redundant load paths. Surface preparation is widely recognized as the key step to producing robust and predictable bonds. Laser ablation imparts both topographical and chemical changes to a surface which can lead to increased bond durability. A laser based process provides an alternative to chemical-dip, manual abrasion and grit blast treatments which are expensive, hazardous, polluting, and less precise. This report documents preliminary testing of a surface preparation technique using laser ablation as a replacement for the chemical etch and abrasive processes currently applied to Ti-6Al-4V alloy adherends. Failure mode, surface roughness, and chemical makeup were analyzed using fluorescence enhanced visualization, microscopy, and X-ray photoelectron spectroscopy, respectively. Single lap shear tests were conducted on bonded and aged specimens to observe bond strength retention and failure mode. Some promising results showed increasing strength and durability of lap shear specimens as laser ablation coverage area and beam intensity increased. Chemical analyses showed trends for surface chemical species which correlated with improved bond strength and durability. Combined, these results suggest that laser ablation is a viable process for inclusion with or/and replacement of one or more currently used titanium surface treatments. On-going work will focus on additional mechanical tests to further demonstrate improved bond durability.

  8. Laser ablation isotope ratio mass spectrometry for enhanced sensitivity and spatial resolution in stable isotope analysis.

    Science.gov (United States)

    Moran, James J; Newburn, Matt K; Alexander, M Lizabeth; Sams, Robert L; Kelly, James F; Kreuzer, Helen W

    2011-05-15

    Stable isotope analysis permits the tracking of physical, chemical, and biological reactions and source materials at a wide variety of spatial scales. We present a laser ablation isotope ratio mass spectrometry (LA-IRMS) method that enables δ(13)C measurement of solid samples at 50 µm spatial resolution. The method does not require sample pre-treatment to physically separate spatial zones. We use laser ablation of solid samples followed by quantitative combustion of the ablated particulates to convert sample carbon into CO(2). Cryofocusing of the resulting CO(2) coupled with modulation in the carrier flow rate permits coherent peak introduction into an isotope ratio mass spectrometer, with only 65 ng carbon required per measurement. We conclusively demonstrate that the measured CO(2) is produced by combustion of laser-ablated aerosols from the sample surface. We measured δ(13)C for a series of solid compounds using laser ablation and traditional solid sample analysis techniques. Both techniques produced consistent isotopic results but the laser ablation method required over two orders of magnitude less sample. We demonstrated that LA-IRMS sensitivity coupled with its 50 µm spatial resolution could be used to measure δ(13) C values along a length of hair, making multiple sample measurements over distances corresponding to a single day's growth. This method will be highly valuable in cases where the δ(13)C analysis of small samples over prescribed spatial distances is required. Suitable applications include forensic analysis of hair samples, investigations of tightly woven microbial systems, and cases of surface analysis where there is a sharp delineation between different components of a sample. Copyright © 2011 John Wiley & Sons, Ltd.

  9. Optimization of silver nanoparticles production by laser ablation in water using a 150-ps laser

    International Nuclear Information System (INIS)

    Stašić, J.; Živković, Lj.; Trtica, M.

    2016-01-01

    Silver nanoparticles were synthesized by laser ablation in liquid (water) using a 150-ps Nd:YAG laser. Due to their extraordinary characteristics, especially when obtained by this method providing high purity and high stability of colloids, silver NPs are nowadays highly important in various applications. The objective of this study was to optimize the process parameters in order to achieve the highest possible yield while retaining small particle size. Yield/mass concentration of the obtained particles was measured depending on different parameters: time of irradiation, pulse energy, position regarding the focus, and number of irradiation locations. The conditions providing relatively high yield, small particle size, highest production rate, and highest efficiency are 7 mJ, 15-min irradiation time (9000 pulses), and target position ∼4 mm in front of the lens focus. The results are compared with the results obtained by the longer nanosecond as well as the ultrashort pulsed lasers. A possible physical explanation is given.

  10. Optimization of silver nanoparticles production by laser ablation in water using a 150-ps laser

    Energy Technology Data Exchange (ETDEWEB)

    Stašić, J.; Živković, Lj.; Trtica, M., E-mail: etrtica@vinca.rs [University of Belgrade, Institute of Nuclear Sciences “Vinča” (Serbia)

    2016-12-15

    Silver nanoparticles were synthesized by laser ablation in liquid (water) using a 150-ps Nd:YAG laser. Due to their extraordinary characteristics, especially when obtained by this method providing high purity and high stability of colloids, silver NPs are nowadays highly important in various applications. The objective of this study was to optimize the process parameters in order to achieve the highest possible yield while retaining small particle size. Yield/mass concentration of the obtained particles was measured depending on different parameters: time of irradiation, pulse energy, position regarding the focus, and number of irradiation locations. The conditions providing relatively high yield, small particle size, highest production rate, and highest efficiency are 7 mJ, 15-min irradiation time (9000 pulses), and target position ∼4 mm in front of the lens focus. The results are compared with the results obtained by the longer nanosecond as well as the ultrashort pulsed lasers. A possible physical explanation is given.

  11. UV laser induced proton-transfer of protein molecule in the gas phase produced by droplet-beam laser ablation

    Science.gov (United States)

    Kohno, Jun-ya; Kondow, Tamotsu

    2008-09-01

    Droplet-beam laser-ablation mass-spectrometry was applied for a study of the UV-laser induced proton-transfer reaction of protonated lysozyme hydrated clusters in the gas phase. Protonated lysozyme hydrated clusters were produced by irradiation of an IR laser onto a droplet-beam of an aqueous solution of lysozyme and were subsequently irradiated by a UV laser. It is found that H + and H 3O + are produced through photodissociation of protonated lysozyme hydrated clusters. The mechanism of the proton-transfer reaction is discussed.

  12. Infrared laser-induced chaos and conformational disorder in a model polymer crystal: Melting vs ablation

    International Nuclear Information System (INIS)

    Sumpter, B.G.; Noid, D.W.; Voth, G.A.; Wunderlich, B.

    1990-01-01

    Molecular dynamics-based computer simulations are presented for the interaction of one and two infrared (IR) laser beams with a model polymer surface. When a single laser beam system is studied over a wide range of intensities, only melting of the polymer, or melting followed by bond dissociation, is observed for up to 100 picoseconds. In contrast, the two-laser simulation results exhibit a marked difference in the energy absorption behavior of the irradiated polymer which, in turn, results in multiple bond dissociations. The results for the one- and two-laser cases studied can be divided into four different classes of physical behavior: (a) the polymer remains in the solid state; (b) the polymer crystal melts; (c) the polymer ablates, but with significant melting (charring); or (d) the polymer ablates with minimal melting. Damage to the model polymer crystal from absorption of energy from either one or two lasers occurs through a mechanism that involves the competition between the absorption of energy and internal energy redistribution. The rate of energy loss from the absorption site(s) relative to the rate of absorption of energy from the radiation field determines rather the polymer melts or ablates (low absorption rates lead to melting or no change and high rates lead to ablation). A sufficiently large rate of energy absorption is only obtainable through the use of two lasers. Two lasers also significantly decrease the total laser intensity required to cause polymer crystal melting. The differences between the one- and two-laser cases are studied by adapting novel signal/subspace techniques to analyze the dynamical changes in the mode spectrum of the polymer as it melts

  13. Estimation of Al2O3 critical temperature using a Langmuir probe in laser ablation

    Science.gov (United States)

    Yahiaoui, K.; Abdelli-Messaci, S.; Messaoud Aberkane, S.; Kellou, A.

    2016-11-01

    Pulsed laser deposition (PLD) has demonstrated its capacity in thin films growing under the moderate laser intensity. But when the laser intensity increases, the presence of droplets on the thin film limits the PLD efficiency such that the process needs an optimization study. In this way, an experimental study has been conducted in order to correlate between the appearance of those droplets and the laser fluence. The comprehension of the physical mechanism during ablation and the control of the deposition parameters allowed to get a safe process. Our experiment consists in measuring the amount of ejected matter from polycrystalline alumina target as a function of the laser fluence when irradiated by a KrF laser. According to laser fluence, several kinds of ablation regimes have been identified. Below a threshold value found as 12 J/cm2, the mechanism of ablation was assigned to normal evaporation, desorption and nonthermal processes. While above this threshold value, the mechanism of ablation was assigned to phase explosion phenomenon which is responsible of droplets formation when the surface temperature approaches the critical temperature T tc. A negative charge collector was used to collect the positive ions in the plume. Their times of flight (TOF) signal were used to estimate the appropriate T tc for alumina target. Ions yield, current as well as kinetic energy were deduced from the TOF signal. Their evolutions show the occurrence of an optical breakdown in the vapor plume which is well correlated with the onset of the phase explosion phenomenon. At 10 J/cm2, the ions velocities collected by the probe have been compared to those obtained from optical emission spectroscopy diagnostic and were discussed. To prove the occurrence of phase explosion by the appearance of droplets, several thin films were elaborated on Si (100) substrate at different laser fluence into vacuum. They have been characterized by scanning electron microscope. The results were well

  14. Laser ablation for analytical sampling: what can we learn from modeling?

    International Nuclear Information System (INIS)

    Bogaerts, Annemie; Chen Zhaoyang; Gijbels, Renaat; Vertes, Akos

    2003-01-01

    The paper is built up in two parts. First, a rather comprehensive introduction is given, with a brief overview of the different application fields of laser ablation, focusing mainly on the analytical applications, and an overview of the different modeling approaches available for laser ablation. Further, a discussion is presented here about the laser evaporated plume expansion in vacuum or in a background gas, as well as about the different mechanisms for particle formation in the laser ablation process, which is most relevant for laser ablation as solid sampling technique for inductively coupled plasma (ICP) spectrometry. In the second part, a model is presented that describes the interaction of an ns-pulsed laser with a Cu target, as well as the resulting plume expansion and plasma formation. The results presented here, include the temperature distribution in the target, the melting and evaporation of the target, the vapor density, velocity and temperature distribution in the evaporated plume, the ionization degree and the density profiles of Cu 0 atoms, Cu + and Cu 2+ ions and electrons in the plume (plasma), as well as the resulting plasma shielding of the incoming laser beam. Results are presented as a function of time during and after the laser pulse, and as a function of position in the target or in the plume. The influence of the target reflection coefficient on the above calculation results is investigated. Finally, the effect of the laser pulse fluence on the target heating, melting and vaporization, and on the plume characteristics and plasma formation is studied. Our modeling results are in reasonable agreement with calculated and measured data from literature

  15. Heat generation caused by ablation of dental restorative materials with an ultra short pulse laser (USPL) system

    Science.gov (United States)

    Braun, Andreas; Wehry, Richard; Brede, Olivier; Frentzen, Matthias; Schelle, Florian

    2011-03-01

    The aim of this study was to assess heat generation in dental restoration materials following laser ablation using an Ultra Short Pulse Laser (USPL) system. Specimens of phosphate cement (PC), ceramic (CE) and composite (C) were used. Ablation was performed with an Nd:YVO4 laser at 1064 nm and a pulse length of 8 ps. Heat generation during laser ablation depended on the thickness of the restoration material. A time delay for temperature increase was observed in the PC and C group. Employing the USPL system for removal of restorative materials, heat generation has to be considered.

  16. An improved three-dimensional two-temperature model for multi-pulse femtosecond laser ablation of aluminum

    International Nuclear Information System (INIS)

    Zhang, Jinping; Chen, Yuping; Hu, Mengning; Chen, Xianfeng

    2015-01-01

    In this paper, an improved three-dimensional two-temperature model for multi-pulse femtosecond laser ablation of aluminum was proposed and proved in our experiment. Aiming to achieve hole-drilling with a high ratio of depth/entrance diameter in vacuum, this model can predict the depth and radius of the drilled holes precisely when employing different laser parameters. Additionally, for multi-pulse laser ablation, we found that the laser fluence and number of pulses are the dominant parameters and the multi-pulse ablation threshold is much lower than the single-pulse one, which will help to obtain high-quality holes

  17. An improved three-dimensional two-temperature model for multi-pulse femtosecond laser ablation of aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jinping; Chen, Yuping, E-mail: ypchen@sjtu.edu.cn; Hu, Mengning; Chen, Xianfeng [State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2015-02-14

    In this paper, an improved three-dimensional two-temperature model for multi-pulse femtosecond laser ablation of aluminum was proposed and proved in our experiment. Aiming to achieve hole-drilling with a high ratio of depth/entrance diameter in vacuum, this model can predict the depth and radius of the drilled holes precisely when employing different laser parameters. Additionally, for multi-pulse laser ablation, we found that the laser fluence and number of pulses are the dominant parameters and the multi-pulse ablation threshold is much lower than the single-pulse one, which will help to obtain high-quality holes.

  18. Impacts of Ambient and Ablation Plasmas on Short- and Ultrashort-Pulse Laser Processing of Surfaces

    Directory of Open Access Journals (Sweden)

    Nadezhda M. Bulgakova

    2014-12-01

    Full Text Available In spite of the fact that more than five decades have passed since the invention of laser, some topics of laser-matter interaction still remain incompletely studied. One of such topics is plasma impact on the overall phenomenon of the interaction and its particular features, including influence of the laser-excited plasma re-radiation, back flux of energetic plasma species, and massive material redeposition, on the surface quality and processing efficiency. In this paper, we analyze different plasma aspects, which go beyond a simple consideration of the well-known effect of plasma shielding of laser radiation. The following effects are considered: ambient gas ionization above the target on material processing with formation of a “plasma pipe”; back heating of the target by both laser-driven ambient and ablation plasmas through conductive and radiative heat transfer; plasma chemical effects on surface processing including microstructure growth on liquid metals; complicated dynamics of the ablation plasma flow interacting with an ambient gas that can result in substantial redeposition of material around the ablation spot. Together with a review summarizing our main to-date achievements and outlining research directions, we present new results underlining importance of laser plasma dynamics and photoionization of the gas environment upon laser processing of materials.

  19. Plasma characterization of cross-beam pulsed-laser ablation used for carbon thin film deposition

    International Nuclear Information System (INIS)

    Sanchez Ake, C.; Sobral, H.; Villagran-Muniz, M.

    2007-01-01

    The dynamics of the interaction between two delayed plasmas induced by cross-beam pulsed-laser ablation was analyzed by fast photography using narrow interference filters. In this configuration, two perpendicular rotating carbon targets were ablated by two synchronized laser beams generating two interacting plasma plumes. A Nd: yttrium-aluminum-garnet (1064 nm) laser beam is focused onto a target generating a highly directed plume; subsequently an excimer laser (248 nm) produces a second perpendicular plasma, which expands through the plume region generated by the first laser. In the cross-beam configuration, collision processes cause a reduction in the C II ion kinetic energy from ∼ 110 to 35 eV; moreover, the species of the second plasma which travel on the normal direction to the target surface (toward the substrate) are mainly C II. Interaction between plasmas has been compared with laser-induced plume propagation through a background gas in terms to the drag model. Carbon thin films were deposited by the cross-beam technique for different delays between lasers. Raman spectroscopy was employed to study the changes in the bonding carbon films as a function of the kinetic energy of ablated C ions

  20. Nickel Nanoparticles Production using Pulsed Laser Ablation under Pressurized CO2

    Science.gov (United States)

    Mardis, Mardiansyah; Takada, Noriharu; Machmudah, Siti; Diono, Wahyu; Kanda, Hideki; Sasaki, Koichi; Goto, Motonobu

    2014-10-01

    We used nickel (Ni) plate as a target and irradiated pulse laser ablation with a fundamental wavelength of 1064 nm under pressurized CO2. The Ni plate was ablated at various pressure (5-15 MPa), temperature (15-80°), and irradiation time (3-30 min). The method successfully generated Ni nanoparticles in various shape and size. Generated Ni nanoparticles collected on a Si wafer and the ablated Ni plate were analyzed by Field Emission Scanning Electron Microscope (FE-SEM). With changing pressure and temperature, the structures of Ni nanoparticles also changed. The shape of generated particles is sphere-like structure with diameter around 10--100 nm. Also it was observed that a network structure of smaller particles was fabricated. The mechanism of nanoparticles fabrication could be explained as follows. Ablated nickel plate melted during the ablation process and larger particles formed, then ejected smaller spherical nanoparticles, which formed nanoclusters attached on the large particles. This morphology of particles was also observed for gold and silver nanoparticles with same condition. Further, the optical emission intensity from ablation plasma and the volume of the ablated crater were also examined under pressurized CO2.

  1. Combination of Q-switched and quasi long-pulsed 1064-nm Nd:YAG laser, non-ablative 1450-nm diode laser, and ablative 10 600-nm carbon dioxide fractional laser for enlarged pores.

    Science.gov (United States)

    Cho, Sung Bin; Noh, Seongmin; Lee, Sang Ju; Kang, Jin Moon; Kim, Young Koo; Lee, Ju Hee

    2010-07-01

    Currently, there is no gold standard for the treatment of enlarged facial pores. In this report, we describe a patient with enlarged nasal pores which were treated with a combination of a non-ablative 1450-nm diode laser, a Q-switched and quasi long-pulsed 1064-nm Nd:YAG laser, and an ablative 10 600-nm carbon dioxide fractional laser system. Four months after the final treatment, the condition of the patient's pores had markedly improved, and the patient was satisfied with the results.

  2. Ridge waveguide lasers in Nd:GGG crystals produced by swift carbon ion irradiation and femtosecond laser ablation.

    Science.gov (United States)

    Jia, Yuechen; Dong, Ningning; Chen, Feng; Vázquez de Aldana, Javier R; Akhmadaliev, Sh; Zhou, Shengqiang

    2012-04-23

    We report on the fabrication of ridge waveguide in Nd:GGG crystal by using swift C(5+) ion irradiation and femtosecond laser ablation. At room temperature continuous wave laser oscillation at wavelength of ~1063 nm has been realized through the optical pump at 808 nm with a slope efficiency of 41.8% and the pump threshold is 71.6 mW. © 2012 Optical Society of America

  3. Impacts of ambient and ablation plasmas on short- and ultrashort-pulse laser processing of surfaces

    Czech Academy of Sciences Publication Activity Database

    Bulgakova, Nadezhda M.; Panchenko, A.N.; Zhukov, V.P.; Kudryashov, S.I.; Pereira, A.; Marine, W.; Mocek, Tomáš; Bulgakov, A.V.

    2014-01-01

    Roč. 5, č. 4 (2014), s. 1344-1372 ISSN 2072-666X R&D Projects: GA MŠk ED2.1.00/01.0027; GA MŠk EE2.3.20.0143 Grant - others:HILASE(XE) CZ.1.05/2.1.00/01.0027; OP VK 6(XE) CZ.1.07/2.3.00/20.0143 Institutional support: RVO:68378271 Keywords : pulsed laser ablation * laser material processing * laser plasma * ambient gas breakdown * material redeposition * plasma pipe formation * microstructures Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.269, year: 2014

  4. Dental hard tissue ablation using mid-infrared tunable nanosecond pulsed Cr:CdSe laser.

    Science.gov (United States)

    Lin, Taichen; Aoki, Akira; Saito, Norihito; Yumoto, Masaki; Nakajima, Sadahiro; Nagasaka, Keigo; Ichinose, Shizuko; Mizutani, Koji; Wada, Satoshi; Izumi, Yuichi

    2016-12-01

    Mid-infrared erbium: yttrium-aluminum-garnet (Er:YAG) and erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) lasers (2.94- and 2.78-μm, respectively) are utilized for effective dental hard tissue treatment because of their high absorption in water, hydroxide ion, or both. Recently, a mid-infrared tunable, nanosecond pulsed, all-solid-state chromium-doped: cadmium-selenide (Cr:CdSe) laser system was developed, which enables laser oscillation in the broad spectral range around 2.9 μm. The purpose of this study was to evaluate the ablation of dental hard tissue by the nanosecond pulsed Cr:CdSe laser at a wavelength range of 2.76-3.00 μm. Enamel, dentin, and cementum tissue were irradiated at a spot or line at a fluence of 0-11.20 J/cm 2 /pulse (energy output: 0-2.00 mJ/pulse) with a repetition rate of 10 Hz and beam diameter of ∼150 μm on the target (pulse width ∼250 ns). After irradiation, morphological changes, ablation threshold, depth, and efficiency, and thickness of the structurally and thermally affected layer of irradiated surfaces were analyzed using stereomicroscopy, scanning electron microscopy (SEM), and light microscopy of non-decalcified histological sections. The nanosecond pulsed irradiation without water spray effectively ablated dental hard tissue with no visible thermal damage such as carbonization. The SEM analysis revealed characteristic micro-irregularities without major melting and cracks in the lased tissue. The ablation threshold of dentin was the lowest at 2.76 μm and the highest at 3.00 μm. The histological analysis revealed minimal thermal and structural changes ∼20 μm wide on the irradiated dentin surfaces with no significant differences between wavelengths. The efficiency of dentin ablation gradually increased from 3.00 to 2.76 μm, at which point the highest ablation efficiency was observed. The nanosecond pulsed Cr:CdSe laser demonstrated an effective ablation ability of hard dental tissues

  5. Laser-ablated active doping technique for visible spectroscopy measurements on Z.

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Matthew Robert

    2013-09-01

    Visible spectroscopy is a powerful diagnostic, allowing plasma parameters ranging from temperature and density to electric and magnetic fields to be measured. Spectroscopic dopants are commonly introduced to make these measurements. On Z, dopants are introduced passively (i.e. a salt deposited on a current-carrying surface); however, in some cases, passive doping can limit the times and locations at which measurements can be made. Active doping utilizes an auxiliary energy source to disperse the dopant independently from the rest of the experiment. The objective of this LDRD project was to explore laser ablation as a method of actively introducing spectroscopic dopants. Ideally, the laser energy would be delivered to the dopant via fiber optic, which would eliminate the need for time-intensive laser alignments in the Z chamber. Experiments conducted in a light lab to assess the feasibility of fibercoupled and open-beam laser-ablated doping are discussed.

  6. Synthesis by picosecond laser ablation of ligand-free Ag and Au nanoparticles for SERS applications

    Science.gov (United States)

    Fazio, Enza; Spadaro, Salvatore; Santoro, Marco; Trusso, Sebastiano; Lucotti, Andrea.; Tommasini, Matteo.; Neri, Fortunato; Maria Ossi, Paolo

    2018-01-01

    The morphological and optical properties of noble metal nanoparticles prepared by picosecond laser generated plasmas in water were investigated. First, the ablation efficiency was maximized searching the optimal focusing conditions. The nanoparticle size, measured by Scanning Transmission Electron Microscopy, strongly depends on the laser fluence, keeping fixed the other deposition parameters such as the target to scanner objective distance and laser repetition frequency. STEM images indicate narrow gradients of NP sizes. Hence the optimization of ablation parameters favours a fine tuning of nanoparticles. UV-Visible spectroscopy helped to determine the appropriate laser wavelength to resonantly excite the localized surface plasmon to carry out Surface Enhanced Raman Scattering (SERS) measurements. The SERS activity of Ag and Au substrates, obtained spraying the colloids synthesized in water, was tested using crystal violet as a probe molecule. The good SERS performance, observed at excitation wavelength 785 nm, is attributed to aggregation phenomena of nanoparticles sprayed on the support.

  7. 3D transient model to predict temperature and ablated areas during laser processing of metallic surfaces

    Directory of Open Access Journals (Sweden)

    Babak. B. Naghshine

    2017-02-01

    Full Text Available Laser processing is one of the most popular small-scale patterning methods and has many applications in semiconductor device fabrication and biomedical engineering. Numerical modelling of this process can be used for better understanding of the process, optimization, and predicting the quality of the final product. An accurate 3D model is presented here for short laser pulses that can predict the ablation depth and temperature distribution on any section of the material in a minimal amount of time. In this transient model, variations of thermal properties, plasma shielding, and phase change are considered. Ablation depth was measured using a 3D optical profiler. Calculated depths are in good agreement with measured values on laser treated titanium surfaces. The proposed model can be applied to a wide range of materials and laser systems.

  8. Ultrashort-pulse laser ablation of gold thin film targets: Theory and experiment

    International Nuclear Information System (INIS)

    Amoruso, S.; Nedyalkov, N.N.; Wang, X.; Ausanio, G.; Bruzzese, R.; Atanasov, P.A.

    2014-01-01

    Laser ablation of a gold thin film irradiated by ultrashort pulses is studied using molecular-dynamics simulations, and compared with that of a bulk target. A film thickness comparable to the ballistic electron depth in gold (≈ 100 nm) is considered, evidencing a significant change of the temperature spatial profile inside the target material, which eventually influences the material decomposition. Particular emphasis is given to the process of nanoparticle generation. The simulations indicate a more uniform heating of the sample in the case of the thin film, which is accompanied by a more homogeneous size distribution of the nanoparticles produced in the ablation process. An experimental characterization of the ultrashort-pulse ablation process is also carried out. The produced nanoparticles are collected on suitable substrates, and atomic force microscopy analysis of less than one layer deposits is performed. An ≈ 2 × narrowing of the nanoparticles equivalent to spherical diameter size distribution is observed in the case of ablation of the gold thin film, in fairly good agreement with the theoretical predictions. Moreover, interesting changes of the nanoparticle shape are evidenced, which are correlated to the changes in the nanoparticle ablation plume dynamics, as studied by time-gated imaging of its self-emission. Our findings suggest ultrashort-pulse laser ablation of thin films as a viable route to achieve a more uniform nanoparticle size distribution. - Highlights: • Nanoparticle generation at fs laser ablation of Au bulk target and thin film is studied. • The spatial confinement in depth at thin film geometry results in homogeneous heating. • Narrower and more homogeneous particle size distribution is observed for thin film

  9. Harmonic generation by atomic and nanoparticle precursors in a ZnS laser ablation plasma

    Energy Technology Data Exchange (ETDEWEB)

    Oujja, M.; Lopez-Quintas, I.; Benítez-Cañete, A.; Nalda, R. de; Castillejo, M., E-mail: marta.castillejo@iqfr.csic.es

    2017-01-15

    Highlights: • Plume species in infrared ns laser ablation of ZnS studied by low-order harmonic generation. • Different spatiotemporal properties of harmonics from atoms and nanoparticles. • Results compared with calculations of optical frequency up-conversion in perturbative regime. - Abstract: Harmonic generation of a driving laser propagating across a laser ablation plasma serves for the diagnosis of multicomponent plumes. Here we study the contribution of atomic and nanoparticle precursors to the generation of coherent ultraviolet and vacuum ultraviolet light as low-order harmonics of the fundamental emission (1064 nm) of a Q-switched Nd:YAG laser in a nanosecond infrared ZnS laser ablation plasma. Odd harmonics from the 3rd up to the 9th order (118.2 nm) have been observed with distinct temporal and spatial characteristics which were determined by varying the delay between the ablation and driving nanosecond pulses and by spatially scanning the plasma with the focused driving beam propagating parallel to the target. At short distances from the target surface (≤1 mm), the harmonic intensity displays two temporal components peaked at around 250 ns and 10 μs. While the early component dies off quickly with increasing harmonic order and vanishes for the 9th order, the late component is notably intense for the 7th harmonic and is still clearly visible for the 9th. Spectral analysis of spontaneous plume emissions help to assign the origin of the two components. While the early plasma component is mainly constituted by neutral Zn atoms, the late component is mostly due to nanoparticles, which upon interaction with the driving laser are subject to breakup and ionization. With the aid of calculations of the phase matching integrals within the perturbative model of optical harmonic generation, these results illustrate how atom and nanoparticle populations, with differing temporal and spatial distributions within the ablation plasma, contribute to the nonlinear

  10. Self-consistent model of the Rayleigh--Taylor instability in ablatively accelerated laser plasma

    International Nuclear Information System (INIS)

    Bychkov, V.V.; Golberg, S.M.; Liberman, M.A.

    1994-01-01

    A self-consistent approach to the problem of the growth rate of the Rayleigh--Taylor instability in laser accelerated targets is developed. The analytical solution of the problem is obtained by solving the complete system of the hydrodynamical equations which include both thermal conductivity and energy release due to absorption of the laser light. The developed theory provides a rigorous justification for the supplementary boundary condition in the limiting case of the discontinuity model. An analysis of the suppression of the Rayleigh--Taylor instability by the ablation flow is done and it is found that there is a good agreement between the obtained solution and the approximate formula σ = 0.9√gk - 3u 1 k, where g is the acceleration, u 1 is the ablation velocity. This paper discusses different regimes of the ablative stabilization and compares them with previous analytical and numerical works

  11. Energy distribution of ions produced by laser ablation of silver in vacuum

    DEFF Research Database (Denmark)

    Christensen, Bo Toftmann; Schou, Jørgen; Canulescu, Stela

    2013-01-01

    the ablation process. A silver target in vacuum was irradiated with a Nd:YAG laser at a wavelength of 355nm and detailed measurements of the time-resolved angular distribution of plume ions were made. In contrast to earlier work, the beam spot was circular such that any flip-over effect of the plume is avoided......The ion energy in a silver ablation plume for fluence in the range of 0.6–2.4Jcm−2, typical for a pulsed laser deposition (PLD) experiment has been investigated. In this fluence range the ion fraction of the ablated particles becomes gradually dominant and can be utilized to characterize...

  12. Nanosecond laser ablation and deposition of silver, copper, zinc and tin

    DEFF Research Database (Denmark)

    Cazzaniga, Andrea Carlo; Ettlinger, Rebecca Bolt; Canulescu, Stela

    2014-01-01

    Nanosecond pulsed laser deposition of different metals (Ag, Cu, Sn, Zn) has been studied in high vacuum at a laser wavelength of 355 nm and pulse length of 6 ns. The deposition rate is roughly similar for Sn, Cu and Ag, which have comparable cohesive energies, and much higher for the deposition...... of Zn which has a low cohesive energy. The deposition rate for all metals is strongly correlated with the total ablation yield, i.e., the total mass ablated per pulse, reported in the literature except for Sn, for which the deposition rate is low, but the total ablation yield is high. This may...... be explained by the continuous erosion by nanoparticles during deposition of the Sn films which appear to have a much rougher surface than those of the other metals studied in the present work....

  13. Plasmonic angular tunability of gold nanoparticles generated by fs laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Pace, M.L.; Guarnaccio, A.; Ranù, F. [CNR, ISM UOS Tito Scalo, Zona Industriale, Tito Scalo (PZ) 85050 (Italy); Trucchi, D. [CNR, ISM UOS Montelibretti, Via Salaria km 29.300, Monterotondo Scalo, (RM) 00015 (Italy); Orlando, S., E-mail: stefano.orlando@ism.cnr.it [CNR, ISM UOS Tito Scalo, Zona Industriale, Tito Scalo (PZ) 85050 (Italy); Mollica, D.; Parisi, G.P. [CNR, ISM UOS Tito Scalo, Zona Industriale, Tito Scalo (PZ) 85050 (Italy); Medici, L.; Lettino, A. [CNR, IMAA, Area della Ricerca di Potenza -Zona Industriale, Tito Scalo, (PZ) 85050 (Italy); De Bonis, A.; Teghil, R. [Dipart. di Scienze,Università della Basilicata, Viale dell’Ateneo Lucano 10, Potenza, 85100 (Italy); Santagata, A. [CNR, ISM UOS Tito Scalo, Zona Industriale, Tito Scalo (PZ) 85050 (Italy)

    2016-06-30

    Highlights: • fs pulsed laser ablation as a technique to produce nanoparticles. • Nanoparticle distribution as an evidence for plasmonic tunable resonances. • Correlation between angular distribution of deposited nanoparticles and specific plasmonic resonances. - Abstract: With the aim to study the influence of deposition parameters on the plasmonic properties of gold (Au) nanoparticles (NPs) deposited by ultra-short ablation, we have focused our attention in evaluating how their size distribution can be varied. In this work, the role played by the NPs’ angular distribution, agglomeration and growth is related to the resulting optical properties. UV–vis-NIR absorption spectra together with Scanning Electron Microscopy, Transmission Electron Microscopy and X-ray microdiffraction observations are presented in order to show how the angular distribution of fs laser ablation and deposition of Au NPs provides different plasmonic properties which can be beneficial for several aims, from optoelectronic to biosensor applications.

  14. Preparation of silver nanoparticles in virgin coconut oil using laser ablation

    Science.gov (United States)

    Zamiri, Reza; Azmi, B Z; Sadrolhosseini, Amir Reza; Ahangar, Hossein Abbastabar; Zaidan, A W; Mahdi, M A

    2011-01-01

    Laser ablation of a silver plate immersed in virgin coconut oil was carried out for fabrication of silver nanoparticles. A Nd:YAG laser at wavelengths of 1064 nm was used for ablation of the plate at different times. The virgin coconut oil allowed formation of nanoparticles with well-dispersed, uniform particle diameters that were stable for a reasonable length of time. The particle sizes and volume fraction of nanoparticles inside the solutions obtained at 15, 30, 45 min ablation times were 4.84, 5.18, 6.33 nm and 1.0 × 10−8, 1.6 × 10−8, 2.4 × 10−8, respectively. The presented method for preparation of silver nanoparticles in virgin coconut oil is environmentally friendly and may be considered a green method. PMID:21289983

  15. Design of a chamber for deposit of thin films by laser ablation

    International Nuclear Information System (INIS)

    Chirino O, S.

    2001-01-01

    The present work has as purpose to design a vacuum chamber, to the one that is denominated chamber of ablation, in which were carried out deposits of thin films using the well-known technique as laser ablation. To fulfill the purpose, the work has been distributed in the following way: in the chapter 1 there are discussed the generalities of the technique of ablation laser for the obtaining of materials in form of thin film, in the chapter 2 the basic concepts of the vacuum technology are mentioned that includes among other things, systems to produce vacuum and vacuum gages and in the chapter 3 the design of the chamber is presented with the accessories and specific systems. (Author)

  16. Post ablation recanalization of varicose veins of the limbs: Comparison ablation method of mechanochemical and laser procedure

    Science.gov (United States)

    Suhartono, R.; Irfan, W.; Wangge, G.; Moenadjat, Y.; Destanto, W. I.

    2017-08-01

    Endovenous ablation has been performed for varicose veins of the limbs in Indonesia since 2010. Endovenous laser ablation (EVLA) therapy has been performed in Cipto Mangunkusumo Hospital (RSCM) in Jakarta, and mechanochemical ablation (MOCA) has been conducted in Fatmawati Hospital. This was a descriptive analytical study, with a cross-sectional design to analyze post-ablation recanalization after MOCA and EVLA procedures. Patients who had undergone MOCA or EVLA treatment were interviewed 3-18 months after the procedures. All the patients underwent vascular ultrasonography (USG) of the operated limb to assess recanalization. Secondary presurgery data were obtained from the patients’ from patients’ medical records. The clinical characteristics of the subjects were recorded to compare the potential correlation between these characteristics and recanalization post-MOCA and EVLA procedures. All the data were analyzed using SPSS ver. 20.0. The study consisted of 43 limbs: 24 treated by MOCA and 19 treated by EVLA. Most subjects in the MOCA group were 7 mm in 13/19 extremities. In the MOCA group, total recanalization occurred in 2/24 extremities, and partial recanalization occurred in 8/24 extremities. In the EVLA group, total recanalization occurred in 1/19 extremities, and partial recanalization occurred in 3/19 extremities. The association between the clinical characteristics of the patients and recanalization was not statistically significant (p > 0.05). The recanalization tendency was higher in the MOCA group than in the EVLA group. Although there was no statistically significant association between the clinical characteristics of the patients and recanalization, the largest diameter of the VSM presurgery (>7 mm) was higher in 3/4 extremities in the MOCA group, as compared to 3/13 extremities in the EVLA group.

  17. The impact of laser ablation on optical soft tissue differentiation for tissue specific laser surgery-an experimental ex vivo study

    Directory of Open Access Journals (Sweden)

    Stelzle Florian

    2012-06-01

    Full Text Available Abstract Background Optical diffuse reflectance can remotely differentiate various bio tissues. To implement this technique in an optical feedback system to guide laser surgery in a tissue-specific way, the alteration of optical tissue properties by laser ablation has to be taken into account. It was the aim of this study to evaluate the general feasibility of optical soft tissue differentiation by diffuse reflectance spectroscopy under the influence of laser ablation, comparing the tissue differentiation results before and after laser intervention. Methods A total of 70 ex vivo tissue samples (5 tissue types were taken from 14 bisected pig heads. Diffuse reflectance spectra were recorded before and after Er:YAG-laser ablation. The spectra were analyzed and differentiated using principal component analysis (PCA, followed by linear discriminant analysis (LDA. To assess the potential of tissue differentiation, area under the curve (AUC, sensitivity and specificity was computed for each pair of tissue types before and after laser ablation, and compared to each other. Results Optical tissue differentiation showed good results before laser exposure (total classification error 13.51%. However, the tissue pair nerve and fat yielded lower AUC results of only 0.75. After laser ablation slightly reduced differentiation results were found with a total classification error of 16.83%. The tissue pair nerve and fat showed enhanced differentiation (AUC: 0.85. Laser ablation reduced the sensitivity in 50% and specificity in 80% of the cases of tissue pair comparison. The sensitivity of nerve–fat differentiation was enhanced by 35%. Conclusions The observed results show the general feasibility of tissue differentiation by diffuse reflectance spectroscopy even under conditions of tissue alteration by laser ablation. The contrast enhancement for the differentiation between nerve and fat tissue after ablation is assumed to be due to laser removal of the

  18. Green synthesis of selenium nanoparticles by excimer pulsed laser ablation in water

    OpenAIRE

    O. Van Overschelde; G. Guisbiers; R. Snyders

    2013-01-01

    Pure selenium nanoparticles were successfully synthesized by Liquid Phase - Pulsed Laser Ablation (LP-PLA) in de-ionized water. Excimer laser (248 nm) operating at low fluence (F ∼ 1 J/cm2) was used to generate colloidal solutions of selenium nanoparticles. The obtained selenium nanoparticles were characterized by UV-visible spectroscopy, Raman spectroscopy, Dynamic Light Scattering, and Transmission Electron Microscopy. We describe the multi-modal size distributions generated and use the cen...

  19. Tuning Optical Nonlinearity of Laser-Ablation-Synthesized Silicon Nanoparticles via Doping Concentration

    Directory of Open Access Journals (Sweden)

    Lianwei Chen

    2014-01-01

    Full Text Available Silicon nanoparticles at different doping concentrations are investigated for tuning their optical nonlinear performance. The silicon nanoparticles are synthesized from doped silicon wafers by pulsed laser ablation. Their dispersions in water are studied for both nonlinear absorption and nonlinear refraction properties. It is found that the optical nonlinear performance can be modified by the doping concentration. Nanoparticles at a higher doping concentration exhibit better saturable absorption performance for femtosecond laser pulse, which is ascribed to the free carrier absorption mechanism.

  20. Note: Laser ablation technique for electrically contacting a buried implant layer in single crystal diamond

    International Nuclear Information System (INIS)

    Ray, M. P.; Baldwin, J. W.; Butler, J. E.; Pate, B. B.; Feygelson, T. I.

    2011-01-01

    The creation of thin, buried, and electrically conducting layers within an otherwise insulating diamond by annealed ion implantation damage is well known. Establishing facile electrical contact to the shallow buried layer has been an unmet challenge. We demonstrate a new method, based on laser micro-machining (laser ablation), to make reliable electrical contact to a buried implant layer in diamond. Comparison is made to focused ion beam milling.

  1. Nanosecond pulsed laser ablation of Ge investigated by employing photoacoustic deflection technique and SEM analysis

    Energy Technology Data Exchange (ETDEWEB)

    Yaseen, Nazish; Bashir, Shazia; Shabbir, Muhammad Kaif; Jalil, Sohail Abdul; Akram, Mahreen; Hayat, Asma; Mahmood, Khaliq; Haq, Faizan-ul; Ahmad, Riaz; Hussain, Tousif

    2016-06-01

    Nanosecond pulsed laser ablation phenomena of single crystal Ge (100) has been investigated by employing photoacoustic deflection as well as SEM analysis techniques. Nd: YAG laser (1064 nm, 10 ns, 1–10 Hz) at various laser fluences ranging from 0.2 to 11 J cm{sup −2} is employed as pump beam to ablate Ge targets. In order to evaluate in-situe ablation threshold fluence of Ge by photoacoustic deflection technique, Continuous Wave (CW) He–Ne laser (632 nm, power 10 mW) is employed as a probe beam. It travels parallel to the target surface at a distance of 3 mm and after passing through Ge plasma it causes deflection due to density gradient of acoustic waves. The deflected signal is detected by photodiode and is recorded by oscilloscope. The threshold fluence of Ge, the velocity of ablated species and the amplitude of the deflected signal are evaluated. The threshold fluence of Ge comes out to be 0.5 J cm{sup −2} and is comparable with the analytical value. In order to compare the estimated value of threshold with ex-situe measurements, the quantitative analysis of laser irradiated Ge is performed by using SEM analysis. For this purpose Ge is exposed to single and multiple shots of 5, 10, 50 and 100 at various laser fluences ranging from 0.2 to 11 J cm{sup −2}. The threshold fluence for single and multiple shots as well as incubation coefficients are evaluated. It is observed that the value of incubation co-efficient decreases with increasing number of pulses and is therefore responsible for lowering the threshold fluence of Ge. SEM analysis also reveals the growth of various features such as porous structures, non-uniform ripples and blisters on the laser irradiated Ge. It is observed that both the fluence as well as number of laser shots plays a significant role for the growth of these structures.

  2. Nanosecond pulsed laser ablation of Ge investigated by employing photoacoustic deflection technique and SEM analysis

    International Nuclear Information System (INIS)

    Yaseen, Nazish; Bashir, Shazia; Shabbir, Muhammad Kaif; Jalil, Sohail Abdul; Akram, Mahreen; Hayat, Asma; Mahmood, Khaliq; Haq, Faizan-ul; Ahmad, Riaz; Hussain, Tousif

    2016-01-01

    Nanosecond pulsed laser ablation phenomena of single crystal Ge (100) has been investigated by employing photoacoustic deflection as well as SEM analysis techniques. Nd: YAG laser (1064 nm, 10 ns, 1–10 Hz) at various laser fluences ranging from 0.2 to 11 J cm −2 is employed as pump beam to ablate Ge targets. In order to evaluate in-situe ablation threshold fluence of Ge by photoacoustic deflection technique, Continuous Wave (CW) He–Ne laser (632 nm, power 10 mW) is employed as a probe beam. It travels parallel to the target surface at a distance of 3 mm and after passing through Ge plasma it causes deflection due to density gradient of acoustic waves. The deflected signal is detected by photodiode and is recorded by oscilloscope. The threshold fluence of Ge, the velocity of ablated species and the amplitude of the deflected signal are evaluated. The threshold fluence of Ge comes out to be 0.5 J cm −2 and is comparable with the analytical value. In order to compare the estimated value of threshold with ex-situe measurements, the quantitative analysis of laser irradiated Ge is performed by using SEM analysis. For this purpose Ge is exposed to single and multiple shots of 5, 10, 50 and 100 at various laser fluences ranging from 0.2 to 11 J cm −2 . The threshold fluence for single and multiple shots as well as incubation coefficients are evaluated. It is observed that the value of incubation co-efficient decreases with increasing number of pulses and is therefore responsible for lowering the threshold fluence of Ge. SEM analysis also reveals the growth of various features such as porous structures, non-uniform ripples and blisters on the laser irradiated Ge. It is observed that both the fluence as well as number of laser shots plays a significant role for the growth of these structures.

  3. Zinc nanoparticles in solution by laser ablation technique

    Indian Academy of Sciences (India)

    TECS

    ablation in aqueous media (PLAAM) has provided a new technique for synthesis of size controlled metallic nanopar- ticles. Metallic nanoparticles in colloidal and powder phase were synthesized using different techniques by several investigators (Mulvaney et al 1993; Macdonald and Smith. 1996; Li et al 2004; Darugar et ...

  4. Stabilization of Au nanoparticles prepared by laser ablation in chloroform with free-base porphyrin molecules

    Czech Academy of Sciences Publication Activity Database

    Šišková, Karolína; Pfleger, Jiří; Procházka, M.

    2010-01-01

    Roč. 256, č. 9 (2010), s. 2979-2987 ISSN 0169-4332 R&D Projects: GA AV ČR KAN100500652; GA ČR GA203/07/0717 Institutional research plan: CEZ:AV0Z40500505 Keywords : Au nanoparticles * laser ablation * chloroform Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.795, year: 2010

  5. Photodynamic therapy using upconversion nanoparticles prepared by laser ablation in liquid

    Energy Technology Data Exchange (ETDEWEB)

    Ikehata, Tomohiro; Onodera, Yuji; Nunokawa, Takashi [Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan); Hirano, Tomohisa; Ogura, Shun-ichiro; Kamachi, Toshiaki [Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan); Odawara, Osamu [Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan); Wada, Hiroyuki, E-mail: wada.h.ac@m.titech.ac.jp [Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan)

    2015-09-01

    Highlights: • Highly crystalline upconversion nanoparticles were prepared by laser ablation in liquid. • Highly transparent near-IR irradiation generated singlet oxygen. • Viability of cancer cells was significantly decreased by near-IR irradiation. - Abstract: Upconversion nanoparticles were prepared by laser ablation in liquid, and the potential use of the nanoparticles for cancer treatment was investigated. A Nd:YAG/SHG laser (532 nm, 13 ns, 10 Hz) was used for ablation, and the cancer treatment studied was photodynamic therapy (PDT). Morphology and crystallinity of prepared nanoparticles were examined by transmission electron microscopy and X-ray diffraction. Red and green emissions resulting from near-infrared excitation were observed by a fluorescence spectrophotometer. Generation of singlet oxygen was confirmed by a photochemical method using 1,3-diphenylisobenzofuran (DPBF). In vitro experiments using cultivated cancer cells were conducted to investigate PDT effects. Uptake of the photosensitizer by cancer cells and cytotoxicities of cancer cells were also examined. We conclude that the combination of PDT and highly crystalline nanoparticles, which were prepared by laser ablation in liquid, is an effective cancer treatment.

  6. Laser ablation of a biliary duct for treatment of a persistent biliary-cutaneous fistula.

    Science.gov (United States)

    Eicher, Chad A; Adelson, Anthony B; Himmelberg, Jeffrey A; Chintalapudi, Udaya

    2008-02-01

    A persistent biliary-cutaneous fistula detected after biliary drainage catheter removal could not be resolved with diversionary techniques and Gelfoam and fibrin glue administration in the fistulous tract. As an alternative approach for treatment of the fistula, obliteration of the contributing bile duct with laser ablation was performed.

  7. Angle-resolved energy distributions of laser ablated silver ions in vacuum

    DEFF Research Database (Denmark)

    Hansen, T.N.; Schou, Jørgen; Lunney, J.G.

    1998-01-01

    The energy distributions of ions ablated from silver in vacuum have been measured in situ for pulsed laser irradiation at 355 nm. We have determined the energy spectra for directions ranging from 5 degrees to 75 degrees with respect to the normal in the intensity range from 100 to 400 MW/cm(2...

  8. IR laser ablative desulfurization of poly (1,4-phenylene sulfide)

    Czech Academy of Sciences Publication Activity Database

    Durani, S. M. A.; Khawaja, E. E.; Masoudi, H. M.; Bastl, Zdeněk; Šubrt, Jan; Galíková, Anna; Pola, Josef

    2005-01-01

    Roč. 73, č. 1 (2005), s. 145-149 ISSN 0165-2370 R&D Projects: GA ČR GA104/04/2028 Institutional research plan: CEZ:AV0Z40400503 Keywords : poly (1,4-phenylene sulfide) * laser ablation * desulfurization Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.265, year: 2005

  9. Some controversies in endovenous laser ablation of varicose veins addressed by optical-thermal mathematical modeling

    NARCIS (Netherlands)

    Poluektova, Anna A.; Malskat, Wendy S. J.; van Gemert, Martin J. C.; Vuylsteke, Marc E.; Bruijninckx, Cornelis M. A.; Neumann, H. A. Martino; van der Geld, Cees W. M.

    2014-01-01

    Minimally invasive treatment of varicose veins by endovenous laser ablation (EVLA) becomes more and more popular. However, despite significant research efforts performed during the last years, there is still a lack of agreement regarding EVLA mechanisms and therapeutic strategies. The aim of this

  10. Diagnosis of laser ablated carbon particles measured by time-resolved X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Miyashita, Atsumi; Yoda, Osamu; Ohyanagi, T.; Murakami, K.

    1995-01-01

    The time and space resolved properties of laser ablated carbon particles were measured by X-ray absorption spectroscopy using LPX as an X-ray source. The energy density of the irradiation laser on the sample was in the range of 0.5-20J/cm 2 and the time delay was varied between 0 and 120ns. The absorption spectra exhibited several peaks originated from level to level transitions and an intense broad absorption in the energy range of C-K edge. At a delay time of 120ns, the absorption peak from 1s→2p transition of neutral carbon atom (C 0 ), C - , C + and C 2+ ions were observed. The absorption peak from C 0 was stronger as the probing position was closer to the sample surface and decreased rapidly with distance from the sample surface. The absorption peak C 2+ ion was observed only at comparatively distant positions from surface. The maximum speeds of highly charged ions were faster than that of neutral atoms and negative charged ions. The neutral atom and lower charged ions were emitted from the sample even after laser irradiation. The spatial distributions of the laser ablated carbon particles in the localized helium gas environment were measured. In the helium gas environment, the ablation plume was depressed by the helium cloud generated on the top of ablation plume. (author)

  11. Endovenous laser ablation (EVLA): a review of mechanisms, modeling outcomes, and issues for debate

    NARCIS (Netherlands)

    W.S.J. Malskat (Wendy S.); A.A. Poluektova (Anna); C.W.M. van der Geld (Cees); H.A.M. Neumann (Martino); R.A. Weiss (Robert); C.M.A. Bruijninckx; M.J.C. van Gemert (Martin)

    2013-01-01

    textabstractEndovenous laser ablation (EVLA) is a commonly used and very effective minimally invasive therapy to manage leg varicosities. Yet, and despite a clinical history of 16 years, no international consensus on a best treatment protocol has been reached so far. Evidence presented in this paper

  12. Ablative fractional laser therapy as treatment for Becker nevus: a randomized controlled pilot study

    NARCIS (Netherlands)

    Meesters, Arne A.; Wind, Bas S.; Kroon, Marije W.; Wolkerstorfer, Albert; van der Veen, J. P. Wietze; Nieuweboer-Krobotová, Ludmila; van der Wal, Allard C.; Bos, Jan D.; Beek, Johan F.

    2011-01-01

    Becker nevus (BN) is an uncommon pigment disorder characterized by hyperpigmentation and sometimes hypertrichosis. To date, no effective treatment has been available. We sought to assess efficacy and safety of ablative 10,600-nm fractional laser therapy (FLT) in the treatment of BN. Eleven patients

  13. Formation of carbon quantum dots and nanodiamonds in laser ablation of a carbon film

    Science.gov (United States)

    Sidorov, A. I.; Lebedev, V. F.; Kobranova, A. A.; Nashchekin, A. V.

    2018-01-01

    We have experimentally shown that nanosecond near-IR pulsed laser ablation of a thin amorphous carbon film produces carbon quantum dots with a graphite structure and nanodiamonds with a characteristic size of 20 - 500 nm on the substrate surface. The formation of these nanostructures is confirmed by electron microscopic images, luminescence spectra and Raman spectra. The mechanisms explaining the observed effects are proposed.

  14. Fabrication of fluorescent nanoparticles of dendronized perylenediimide by laser ablation in water

    NARCIS (Netherlands)

    Yasukuni, R.; Asahi, T.; Sugiyama, T.; Masuhara, H.; Sliwa, M.; Hofkens, J.; De Schryver, F. C.; Van der Auweraer, M.; Herrmann, A.; Mueller, K.; Müllen, K.

    2008-01-01

    Highly fluorescent organic nanoparticles with size of about 300 nm were prepared by nanosecond laser ablation of micrometer-sized powder of dendronized perylenediimide dispersed in water. The nanoparticle colloidal solution provided a fluorescence quantum yield of 0.58. The absorption and emission

  15. Ion time-of-flight study of laser ablation of silver in low pressure gases

    DEFF Research Database (Denmark)

    Hansen, T.N.; Schou, Jørgen; Lunney, J.G.

    1999-01-01

    The dynamics of ions from a laser-ablated silver target in low pressure background atmospheres have been investigated in a simple geometry using an electrical probe. A simple scattering picture for the first transmitted peak of the observed plume splitting has been used to calculate cross sections...

  16. Laser Ablative Structural Modification of Poly(ethylene-alt-maleic anhydride)

    Czech Academy of Sciences Publication Activity Database

    Pola, Josef; Kupčík, Jaroslav; Durani, S. M. A.; Khavaja, E. E.; Masoudi, H. M.; Bastl, Zdeněk; Šubrt, Jan

    2003-01-01

    Roč. 15, č. 20 (2003), s. 3887-3893 ISSN 0897-4756 Institutional research plan: CEZ:AV0Z4032918; CEZ:AV0Z4072921 Keywords : laser ablation * poly(ethylene- alt -maleic)anhydride Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 4.374, year: 2003

  17. Analysis of roll-stamped light guide plate fabricated with laser-ablated stamper

    Science.gov (United States)

    Na, Hyunjun; Hong, Seokkwan; Kim, Jongsun; Hwang, Jeongho; Joo, Byungyun; Yoon, Kyunghwan; Kang, Jeongjin

    2017-12-01

    LGP (light guide plate) is one of the major components of LCD (liquid crystal display), and it makes surface illumination for LCD backlit. LGP is a transparent plastic plate usually produced by injection molding process. On the back of LGP there are micron size patterns for extraction of light. Recently a roll-stamping process has achieved the high mass productivity of thinner LGPs. In order to fabricate optical patterns on LGPs, a fabricating tool called as a stamper is used. Micro patterns on metallic stampers are made by several micro machining processes such as chemical etching, LIGA-reflow, and laser ablation. In this study, a roll-stamping process by using a laser ablated metallic stamper was dealt with in consideration of the compatibility with the roll-stamping process. LGP fabricating tests were performed using a roll-stamping process with four different roll pressures. Pattern shapes on the stamper fabricated by laser ablation and transcription ratios of the roll-stamping process were analyzed, and LGP luminance was evaluated. Based on the evaluation, optical simulation model for LGP was made and simulation accuracy was evaluated. Simulation results showed good agreements with optical performance of LGPs in the brightness and uniformity. It was also shown that the roll-stamped LGP has the possibility of better optical performance than the conventional injection molded LGP. It was also shown that the roll-stamped LGP with the laser ablated stamper is potential to have better optical performance than the conventional injection molded LGP.

  18. Optical-thermal mathematical model for endovenous laser ablation of varicose veins

    NARCIS (Netherlands)

    P.W.M. van Ruijven (Peter); A.A. Poluektova (Anna); M.J.C. van Gemert (Martin); H.A.M. Neumann (Martino); T.E.C. Nijsten (Tamar); C.W.M. van der Geld (Cees)

    2014-01-01

    textabstractEndovenous laser ablation (EVLA) is successfully used to treat varicose veins. However, the exact working mechanism is still not fully identified and the clinical procedure is not yet standardized. Mathematical modeling of EVLA could strongly improve our understanding of the influence of

  19. Optical-thermal mathematical model for endovenous laser ablation of varicose veins

    NARCIS (Netherlands)

    van Ruijven, Peter W. M.; Poluektova, Anna A.; van Gemert, Martin J. C.; Neumann, H. A. Martino; Nijsten, Tamar; van der Geld, Cees W. M.

    2014-01-01

    Endovenous laser ablation (EVLA) is successfully used to treat varicose veins. However, the exact working mechanism is still not fully identified and the clinical procedure is not yet standardized. Mathematical modeling of EVLA could strongly improve our understanding of the influence of the various

  20. Evolution of the plasma parameters in the expanding laser ablation plume of silver

    DEFF Research Database (Denmark)

    Christensen, Bo Toftmann; Schou, Jørgen; Hansen, T.N.

    2002-01-01

    The angular and radial variation of the ion density and electron temperature in the plasma plume produced by laser ablation of silver at fluences of 0.8-1.3 J cm(-2) at 355 nm have been studied using a time-resolving Langmuir probe. The angular dependence of the electron temperature...

  1. Perspective on One Decade of Laser Propulsion Research at the Air Force Research Laboratory, November 1995-2005 (DVD)

    National Research Council Canada - National Science Library

    2007-01-01

    .... PHYSICAL DESCRIPTION: 1 DVD-ROM and 1 CD-ROM; 4 3/4 in.; 395 MB. ABSTRACT: A short film and presentation on laser propulsion research at the Air Force Research Laboratory, spanning November 1995 through October 2005...

  2. Evaluation of laser ablation of knee cartilage as an alternative to microfracture surgery: pilot investigations

    Science.gov (United States)

    Su, Erica; Wong, Brian J. F.; Sun, Hui; Juhasz, Tibor

    2010-02-01

    An emerging clinical treatment option for articular cartilage injury includes bone marrow stimulation techniques, such as microfracture, which has grown increasingly popular among athletes. During the microfracture procedure, the surgeon penetrates the subchondral bone with an awl and creates "microholes" deep enough to ensure bleeding from the bone marrow. This procedure triggers a spontaneous repair response that results in the formation of fibrocartilaginous repair tissue. This preliminary study aimed to evaluate the potential use of femtosecond lasers and Erbium:YAG lasers as alternatives to microfracture surgery of the knee by assessing the effects of ablation on bovine femoral condyles. Bovine femoral condyles were obtained and 8mm cube blocks were extracted. The specimen were ablated with various laser dosimetry parameters and observed using a high power dissecting microscope to examine the effects of the lasers. Further imaging with conventional histology (hematoxylin and eosin staining) was done to provide more accurate information. Preliminary results show some carbonization but demonstrate little thermal damage to surrounding tissues. The femtosecond laser offers a more precise and efficient ablation than the Erbium:YAG laser, but both are demonstrated to be possible alternatives to the surgical-skill dependent microfracture procedure.

  3. Non-Fourier heat conduction and phase transition in laser ablation of polytetrafluoroethylene (PTFE)

    Science.gov (United States)

    Zhang, Yu; Zhang, Daixian; Wu, Jianjun; Li, Jian; He, Zhaofu

    2017-11-01

    The phase transition in heat conduction of polytetrafluoroethylene-like polymers was investigated and applied in many fields of science and engineering. Considering more details including internal absorption of laser radiation, reflectivity of material and non-Fourier effect etc., the combined heat conduction and phase transition in laser ablation of polytetrafluoroethylene were modeled and investigated numerically. The thermal and mechanic issues in laser ablation were illustrated and analyzed. Especially, the phenomenon of temperature discontinuity formed in the combined phase transition and non-Fourier heat conduction was discussed. Comparisons of target temperature profiles between Fourier and non-Fourier heat conduction in melting process were implemented. It was indicated that the effect of non-Fourier plays an important role in the temperature evolvement. The effect of laser fluence was proven to be significant and the thermal wave propagation was independent on the laser intensity for the non-Fourier heat conduction. Besides, the effect of absorption coefficients on temperature evolvements was studied. For different ranges of absorption coefficients, different temperature evolvements can be achieved. The above numerical simulation provided insight into physical processes of combined non-Fourier heat conduction and phase transition in laser ablation.

  4. A comparison of the DPSS UV laser ablation characteristic of 1024 and H10F WC-Co

    Science.gov (United States)

    See, Tian Long; Chantzis, Dimitrios; Royer, Raphael; Metsios, Ioannis; Antar, Mohammad; Marimuthu, Sundar

    2017-07-01

    An investigation on ablation characteristics of 1024 and H10F cobalt cemented tungsten carbide (WC-Co) with a DPSS nanosecond UV laser (50 ns pulse width, 355 nm wavelength, 90 W average power and 10 kHz repetition rate) is presented. The ablation characteristic parameters such as ablation threshold, incubation effect and optical penetration depth were evaluated based on the spot ablation diameter and depth. It was observed that the ablation threshold is significantly influenced by the number of pulses (NOP) and it decreases with increase NOP which is attributed to the incubation effect. Only one ablation region is observed at low laser fluence and an additional molten ablation region is observed at high laser fluence accompanied with cracks. The cracks formation is due to the thermal induced stress and changes in WC microstructure during laser beam irradiation. The crack depth is proportional to the thickness of the molten WC region. The ablation threshold of 1024 WC-Co and H10F WC-Co were found to be Fth1 =4.32 J/cm2 and Fth1 =4.26 J/cm2 respectively. The difference in chemical composition has insignificant effect on the ablation threshold value of the material. The incubation factor and optical penetration depth values of 1024 WC-Co and H10F WC-Co were found to be ξ=0.73, α-1 =411 nm and ξ=0.75, α-1 =397 nm respectively.

  5. In Situ Geochemical Analysis and Age Dating of Rocks Using Laser Ablation-Miniature Mass Spectrometer

    Science.gov (United States)

    Sinha, Mahadeva P.; Hecht, Michael H.; Hurowitz, Joel A.

    2012-01-01

    A miniaturized instrument for performing chemical and isotopic analysis of rocks has been developed. The rock sample is ablated by a laser and the neutral species produced are analyzed using the JPL-invented miniature mass spectrometer. The direct sampling of neutral ablated material and the simultaneous measurement of all the elemental and isotopic species are the novelties of this method. In this laser ablation-miniature mass spectrometer (LA-MMS) method, the ablated neutral atoms are led into the electron impact ionization source of the MMS, where they are ionized by a 70-eV electron beam. This results in a secondary ion pulse typically 10-100 microsecond wide, compared to the original 5-10-nanosecond laser pulse duration. Ions of different masses are then spatially dispersed along the focal plane of the magnetic sector of the miniature mass spectrometer and measured in parallel by a modified CCD (charge-coupled device) array detector capable of detecting ions directly. Compared to conventional scanning techniques, simultaneous measurement of the ion pulse along the focal plane effectively offers a 100% duty cycle over a wide mass range. LAMMS offers a more quantitative assessment of elemental composition than techniques that detect laser-ionized species produced directly in the ablation process because the latter can be strongly influenced by matrix effects that vary with the structure and geometry of the surface, the laser beam, and the ionization energies of the elements. The measurement of high-precision isotopic ratios and elemental composition of different rock minerals by LAMMS method has been demonstrated. The LA-MMS can be applied for the absolute age determination of rocks. There is no such instrument available presently in a miniaturized version that can be used for NASA space missions. Work is in progress in the laboratory for geochronology of rocks using LA-MMS that is based on K-Ar radiogenic dating technique.

  6. Dynamics of excimer laser-ablated aluminum neutral atom plume measured by dye laser resonance absorption photography

    International Nuclear Information System (INIS)

    Gilgenbach, R.M.; Ventzek, P.L.G.

    1991-01-01

    We report the first dye laser resonance absorption photographs of a single species of aluminum ground-state neutral atoms in the plume ablated from solid aluminum by KrF excimer laser radiation. Aluminum ground-state neutral atoms were diagnosed by illuminating the ablated plume with a dye laser tuned to the 3 2 P 1/2 --4 2 S 1/2 transition at 394.4 nm. Measurements have been performed in vacuum as well as in argon and air environments. Streaming velocities measured for neutral aluminum atoms in vacuum ranged from 0.5x10 6 cm/s at low excimer laser fluences of 1--2 J/cm 2 to 3.4x10 6 cm/s at high fluences of 7 J/cm 2 . Dye laser resonance absorption photography measurements of ablated aluminum in argon and air showed slower expansion at 50 and 200 Torr, while observations at 760 Torr indicate turbulent mixing of aluminum neutrals near the surface. Differences between data in argon and air may be due to oxidation of neutral aluminum atoms

  7. Substrate-Mediated Laser Ablation under Ambient Conditions for Spatially-Resolved Tissue Proteomics.

    Science.gov (United States)

    Fatou, Benoit; Wisztorski, Maxence; Focsa, Cristian; Salzet, Michel; Ziskind, Michael; Fournier, Isabelle

    2015-12-17

    Numerous applications of ambient Mass Spectrometry (MS) have been demonstrated over the past decade. They promoted the emergence of various micro-sampling techniques such as Laser Ablation/Droplet Capture (LADC). LADC consists in the ablation of analytes from a surface and their subsequent capture in a solvent droplet which can then be analyzed by MS. LADC is thus generally performed in the UV or IR range, using a wavelength at which analytes or the matrix absorb. In this work, we explore the potential of visible range LADC (532 nm) as a micro-sampling technology for large-scale proteomics analyses. We demonstrate that biomolecule analyses using 532 nm LADC are possible, despite the low absorbance of biomolecules at this wavelength. This is due to the preponderance of an indirect substrate-mediated ablation mechanism at low laser energy which contrasts with the conventional direct ablation driven by sample absorption. Using our custom LADC system and taking advantage of this substrate-mediated ablation mechanism, we were able to perform large-scale proteomic analyses of micro-sampled tissue sections and demonstrated the possible identification of proteins with relevant biological functions. Consequently, the 532 nm LADC technique offers a new tool for biological and clinical applications.

  8. Substrate-Mediated Laser Ablation under Ambient Conditions for Spatially-Resolved Tissue Proteomics

    Science.gov (United States)

    Fatou, Benoit; Wisztorski, Maxence; Focsa, Cristian; Salzet, Michel; Ziskind, Michael; Fournier, Isabelle

    2015-01-01

    Numerous applications of ambient Mass Spectrometry (MS) have been demonstrated over the past decade. They promoted the emergence of various micro-sampling techniques such as Laser Ablation/Droplet Capture (LADC). LADC consists in the ablation of analytes from a surface and their subsequent capture in a solvent droplet which can then be analyzed by MS. LADC is thus generally performed in the UV or IR range, using a wavelength at which analytes or the matrix absorb. In this work, we explore the potential of visible range LADC (532 nm) as a micro-sampling technology for large-scale proteomics analyses. We demonstrate that biomolecule analyses using 532 nm LADC are possible, despite the low absorbance of biomolecules at this wavelength. This is due to the preponderance of an indirect substrate-mediated ablation mechanism at low laser energy which contrasts with the conventional direct ablation driven by sample absorption. Using our custom LADC system and taking advantage of this substrate-mediated ablation mechanism, we were able to perform large-scale proteomic analyses of micro-sampled tissue sections and demonstrated the possible identification of proteins with relevant biological functions. Consequently, the 532 nm LADC technique offers a new tool for biological and clinical applications. PMID:26674367

  9. Fabrication of gold and silver nanoparticles with pulsed laser ablation under pressurized CO2

    Science.gov (United States)

    Machmudah, Siti; Wahyudiono; Takada, Noriharu; Kanda, Hideki; Sasaki, Koichi; Goto, Motonobu

    2013-12-01

    Pulsed laser ablation (PLA) has become a promising method for the synthesis of nanoclusters for photonics, electronics and medicine. In this work PLA in pressurized CO2 has been applied for fabrication of gold and silver nanoparticles. Laser ablation was performed with an excitation wavelength of 532 nm under various pressures (0.1-20 MPa), temperatures (40-80 °C) of CO2 medium and ablation times (1500-9000 s). On the basis of the experimental result, it follows that structures of gold (Au) and silver (Ag) nanoparticles were significantly affected by the changes in CO2 density. The structures of gold and silver nanoparticles also changed with an increase of ablation time. From a field-emission scanning electron microscopy (FE-SEM) image of the fabricated gold nano-structured particles on silicon wafer, it was seen that a network structure of smaller gold particles was fabricated. A similar morphology of particles fabricated from silver plate was observed. Silver particles contain nanoparticles with large-varied diameter ranging from 5 nm to 1.2 μm. The mechanism of nanoparticles fabrication could be observed as follows. Bigger gold/silver particles melted during the ablation process and then ejected smaller spherical nanoparticles, which formed nanoclusters attached on the molten particles.

  10. CuInGaSe{sub 2} nanoparticles by pulsed laser ablation in liquid medium

    Energy Technology Data Exchange (ETDEWEB)

    Mendivil, M.I.; García, L.V. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); Krishnan, B. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); CIIDIT—Universidad Autónoma de Nuevo León, Apodaca, Nuevo León (Mexico); Avellaneda, D. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); and others

    2015-12-15

    Highlights: • CIGS nanocolloids were synthesized using PLAL technique. • Characterized their morphology, structure, composition and optical properties. • Morphologies were dependent on ablation wavelength and liquid medium. • Optical absorption and bandgap of these nanocolloids were tunable. - Abstract: Pulsed laser ablation in liquid medium (PLALM) is a nanofabrication technique to produce complex nanostructures. CuInGaSe{sub 2} (CIGS) is an alloy with applications in photovoltaic industry. In this work, we studied the effects of laser ablation wavelength, energy fluence and liquid medium on the properties of the CIGS nanoparticles synthesized by PLALM. The nanoparticles obtained were analyzed by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS) and UV–vis absorption spectroscopy. XPS results confirmed the chemical states and composition of the ablated products. TEM analysis showed different morphologies for the nanomaterials obtained in different liquid media and ablation wavelengths. The optical properties for these CIGS nanocolloids were analyzed using UV–vis absorption spectroscopy. The results demonstrated the use of PLALM as a useful synthesis technique for nanoparticles of quaternary photovoltaic materials.

  11. Fabrication of gold and silver nanoparticles with pulsed laser ablation under pressurized CO2

    International Nuclear Information System (INIS)

    Machmudah, Siti; Wahyudiono; Kanda, Hideki; Goto, Motonobu; Takada, Noriharu; Sasaki, Koichi

    2013-01-01

    Pulsed laser ablation (PLA) has become a promising method for the synthesis of nanoclusters for photonics, electronics and medicine. In this work PLA in pressurized CO 2 has been applied for fabrication of gold and silver nanoparticles. Laser ablation was performed with an excitation wavelength of 532 nm under various pressures (0.1–20 MPa), temperatures (40–80 °C) of CO 2 medium and ablation times (1500–9000 s). On the basis of the experimental result, it follows that structures of gold (Au) and silver (Ag) nanoparticles were significantly affected by the changes in CO 2 density. The structures of gold and silver nanoparticles also changed with an increase of ablation time. From a field-emission scanning electron microscopy (FE-SEM) image of the fabricated gold nano-structured particles on silicon wafer, it was seen that a network structure of smaller gold particles was fabricated. A similar morphology of particles fabricated from silver plate was observed. Silver particles contain nanoparticles with large-varied diameter ranging from 5 nm to 1.2 μm. The mechanism of nanoparticles fabrication could be observed as follows. Bigger gold/silver particles melted during the ablation process and then ejected smaller spherical nanoparticles, which formed nanoclusters attached on the molten particles. (paper)

  12. Ablation by-products of dental materials from the Er:YAG laser and the dental handpiece

    Science.gov (United States)

    Wigdor, Harvey A.; Visuri, Steven R.; Walsh, Joseph T., Jr.

    1995-05-01

    Recently there has been much interest in lasers and their potential use to replace the dental drill. The research has been directed towards vital dental tissues. It must be understood that any laser to be used in dentistry which will replace the dental drill must also ablate and remove existing dental materials. Some concern exists about the ablation products when the Er:YAG laser is used to ablate dental materials. It is incumbent on the professionals using these lasers to understand the materials being produced by these lasers and protect themselves and their patients from possible toxic products. It is the intent of this paper to evaluate the products produced by the ablation of both dental amalgam and composite dental restorative materials and compare them with those produced by the traditional dental handpiece (drill).

  13. Synthesis of silver nanoparticles by laser ablation in ethanol: A pulsed photoacoustic study

    International Nuclear Information System (INIS)

    Valverde-Alva, M.A.; García-Fernández, T.; Villagrán-Muniz, M.; Sánchez-Aké, C.; Castañeda-Guzmán, R.; Esparza-Alegría, E.; Sánchez-Valdés, C.F.

    2015-01-01

    Graphical abstract: - Highlights: • Pulsed photoacoustic technique allowed to determine the production rate of NPs. • Pulsed photoacoustic technique allows to determine the Ag concentration in colloids. • The nanoparticles production rate drops quickly during the first laser pulses. • Nanoparticles production rate is almost constant after few hundreds of laser shots. • Photoacoustic signal amplitude was proportional to fluence on the target surface. - Abstract: The pulsed photoacoustic (PA) technique was used to study the synthesis by laser ablation of silver nanoparticles (Ag-NPs) in ethanol. PA technique allowed to determine the production rate per laser pulse and concentration of synthesized Ag-NPs. The samples were produced by using a pulsed Nd:YAG laser with 1064 nm of wavelength and 7 ns of pulse duration. The laser pulse energy varied from 10 to 100 mJ. Transmission electron microscopy micrographs demonstrated that the obtained nanoparticles were spherical with an average size close to 10 nm. The absorption spectra of the colloids showed a plasmon absorption peak around 400 nm. The PA analyses showed a significant reduction of the production rate of Ag-NPs during the first hundreds of laser pulses. For a higher number of pulses this rate was kept almost constant. Finally, we found that the root mean square (RMS) value of the PA signal was proportional to the laser pulse fluence on the target surface. Thus PA technique was useful to monitor the ablation process.

  14. Synthesis of silver nanoparticles by laser ablation in ethanol: A pulsed photoacoustic study

    Energy Technology Data Exchange (ETDEWEB)

    Valverde-Alva, M.A., E-mail: azbmiguel@gmail.com [Posgrado en Ciencia e Ingeniería de Materiales, Universidad Nacional Autónoma de México (UNAM), México D.F., C.P. 04510, México (Mexico); García-Fernández, T. [Universidad Autónoma de la Ciudad de México (UACM), Prolongación San Isidro 151, Col. San Lorenzo Tezonco, México D.F., C.P. 09790, México (Mexico); Villagrán-Muniz, M.; Sánchez-Aké, C.; Castañeda-Guzmán, R. [CCADET Universidad Nacional Autónoma de México (UNAM), México D.F., C.P. 04510, México (Mexico); Esparza-Alegría, E. [Facultad de Ciencias, Universidad Nacional Autónoma de México (UNAM), México D.F., C.P. 04510, México (Mexico); Sánchez-Valdés, C.F. [Instituto Potosino de Investigación Científica y Tecnológica A.C., Camino a la Presa San José 2055, Col. Lomas 4a sección, San Luis Potosí, S.L.P., C.P. 78216, México (Mexico); and others

    2015-11-15

    Graphical abstract: - Highlights: • Pulsed photoacoustic technique allowed to determine the production rate of NPs. • Pulsed photoacoustic technique allows to determine the Ag concentration in colloids. • The nanoparticles production rate drops quickly during the first laser pulses. • Nanoparticles production rate is almost constant after few hundreds of laser shots. • Photoacoustic signal amplitude was proportional to fluence on the target surface. - Abstract: The pulsed photoacoustic (PA) technique was used to study the synthesis by laser ablation of silver nanoparticles (Ag-NPs) in ethanol. PA technique allowed to determine the production rate per laser pulse and concentration of synthesized Ag-NPs. The samples were produced by using a pulsed Nd:YAG laser with 1064 nm of wavelength and 7 ns of pulse duration. The laser pulse energy varied from 10 to 100 mJ. Transmission electron microscopy micrographs demonstrated that the obtained nanoparticles were spherical with an average size close to 10 nm. The absorption spectra of the colloids showed a plasmon absorption peak around 400 nm. The PA analyses showed a significant reduction of the production rate of Ag-NPs during the first hundreds of laser pulses. For a higher number of pulses this rate was kept almost constant. Finally, we found that the root mean square (RMS) value of the PA signal was proportional to the laser pulse fluence on the target surface. Thus PA technique was useful to monitor the ablation process.

  15. Ultrafast laser ablation in liquids for nanomaterials and applications.

    Science.gov (United States)

    Rao, S Venugopal; Podagatlapalli, G Krishna; Hamad, Syed

    2014-02-01

    We present an inclusive overview of the ultrafast ablation technique performed in liquids. Being a comparatively new method, we bring out the recent progress achieved, present the challenges ahead, and outline the future prospects for this technique. The review is conveniently divided into five parts: (a) a succinct preamble to the technique of ultrafast ablation in liquids (ULAL) is provided. A brief introduction to the conventional ns ablation is also presented for the sake of completeness (b) fundamental physical processes involved in this technique are elaborated (c) specific advantages of the technique compared to other physical and chemical methodologies are enumerated (d) applications of this technique in photonics; biomedical and explosives detection [using surface-enhanced Raman scattering (SERS)] is updated (e) future prospects describing the potential of this technique for creating unique nanoparticles (NPs) and nanostructures (NSs) for niche applications. We also discuss some of the recently reported significant results achieved in a variety of materials, especially metals, using this technique. Furthermore, we present some of our own experimental data obtained from ULAL of Ag, Cu, and Zn in a variety of liquids such as acetone, water, acetonitrile etc. The generated NPs (colloidal solutions) and NSs (on substrates) have been successfully utilized for nonlinear optical, SERS, and biomedical applications.

  16. Carbon dioxide laser ablation with immediate autografting in a full-thickness porcine burn model.

    Science.gov (United States)

    Glatter, R D; Goldberg, J S; Schomacker, K T; Compton, C C; Flotte, T J; Bua, D P; Greaves, K W; Nishioka, N S; Sheridan, R L

    1998-08-01

    To compare the long-term clinical and histologic outcome of immediate autografting of full-thickness burn wounds ablated with a high-power continuous-wave CO2 laser to sharply débrided wounds in a porcine model. Continuous-wave CO2 lasers have performed poorly as tools for burn excision because the large amount of thermal damage to viable subeschar tissues precluded successful autografting. However, a new technique, in which a high-power laser is rapidly scanned over the eschar, results in eschar vaporization without significant damage to underlying viable tissues, allowing successful immediate autografting. Full-thickness paravertebral burn wounds measuring 36 cm2 were created on 11 farm swine. Wounds were ablated to adipose tissue 48 hours later using either a surgical blade or a 150-Watt continuous-wave CO2 laser deflected by an x-y galvanometric scanner that translated the beam over the tissue surface, removing 200 microm of tissue per scan. Both sites were immediately autografted and serially evaluated clinically and histologically for 180 days. The laser-treated sites were nearly bloodless. The mean residual thermal damage was 0.18+/-0.05 mm. The mean graft take was 96+/-11% in manual sites and 93+/-8% in laser sites. On postoperative day 7, the thickness of granulation tissue at the graft-wound bed interface was greater in laser-debrided sites. By postoperative day 180, the manual and laser sites were histologically identical. Vancouver scar assessment revealed no differences in scarring at postoperative day 180. Long-term scarring, based on Vancouver scar assessments and histologic evaluation, was equivalent at 6 months in laser-ablated and sharply excised sites. Should this technology become practical, the potential clinical implications include a reduction in surgical blood loss without sacrifice of immediate engraftment rates or long-term outcome.

  17. Inductively Coupled Plasma: Fundamental Particle Investigations with Laser Ablation and Applications in Magnetic Sector Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Saetveit, Nathan Joe [Iowa State Univ., Ames, IA (United States)

    2008-01-01

    Particle size effects and elemental fractionation in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) are investigated with nanosecond and femtosecond laser ablation, differential mobility analysis, and magnetic sector ICP-MS. Laser pulse width was found to have a significant influence on the LA particle size distribution and the elemental composition of the aerosol and thus fractionation. Emission from individual particles from solution nebulization, glass, and a pressed powder pellet are observed with high speed digital photography. The presence of intact particles in an ICP is shown to be a likely source of fractionation. A technique for the online detection of stimulated elemental release from neural tissue using magnetic sector ICP-MS is described. Detection limits of 1 μg L-1 or better were found for P, Mn, Fe, Cu, and Zn in a 60 μL injection in a physiological saline matrix.

  18. Inductively Coupled Plasma: Fundamental Particle Investigations with Laser Ablation and Applications in Magnetic Sector Mass Spectrometry

    International Nuclear Information System (INIS)

    Nathan Joe Saetveit

    2008-01-01

    Particle size effects and elemental fractionation in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) are investigated with nanosecond and femtosecond laser ablation, differential mobility analysis, and magnetic sector ICP-MS. Laser pulse width was found to have a significant influence on the LA particle size distribution and the elemental composition of the aerosol and thus fractionation. Emission from individual particles from solution nebulization, glass, and a pressed powder pellet are observed with high speed digital photography. The presence of intact particles in an ICP is shown to be a likely source of fractionation. A technique for the online detection of stimulated elemental release from neural tissue using magnetic sector ICP-MS is described. Detection limits of 1 (micro)g L -1 or better were found for P, Mn, Fe, Cu, and Zn in a 60 (micro)L injection in a physiological saline matrix

  19. Trace contaminant determination in fish scale by laser-ablation technique

    International Nuclear Information System (INIS)

    Lee, I.; Coutant, C.C.; Arakawa, E.T.

    1993-01-01

    Laser ablation on rings of fish scale has been used to analyze the historical accumulation of polychlorinated biphenyls (PCB) in striped bass in the Watts Bar Reservoir. Rings on a fish scale grow in a pattern that forms a record of the fish's chemical intake. In conjunction with the migration patterns of fish monitored by ecologists, relative PCB concentrations in the seasonal rings of fish scale can be used to study the PCB distribution in the reservoir. In this study, a tightly-focused laser beam from a XeCl excimer laser was used to ablate and ionize a small portion of a fish scale placed in a vacuum chamber. The ions were identified and quantified by a time-of-flight mass spectrometer. Studies of this type can provide valuable information for the Department of Energy (DOE) off-site clean-up efforts as well as identifying the impacts of other sources to local aquatic populations

  20. Femtosecond laser ablation of polymeric substrates for the fabrication of microfluidic channels

    International Nuclear Information System (INIS)

    Suriano, Raffaella; Kuznetsov, Arseniy; Eaton, Shane M.; Kiyan, Roman; Cerullo, Giulio; Osellame, Roberto; Chichkov, Boris N.; Levi, Marinella; Turri, Stefano

    2011-01-01

    This manuscript presents a study of physical and chemical properties of microchannels fabricated by femtosecond laser processing technology in thermoplastic polymeric materials, including poly(methyl methacrylate) (PMMA), polystyrene (PS) and cyclic olefin polymer (COP). By surface electron microscopy and optical profilometry, the dimensions of microchannels in the polymers were found to be easily tunable, with surface roughness values comparable to those obtained by standard prototyping techniques such as micromilling. Through colorimetric analysis and optical microscopy, PMMA was found to remain nearly transparent after ablation while COP and PS darkened significantly. Using infrared spectroscopy, the darkening in PS and COP was attributed to significant oxidation and dehydrogenation during laser ablation, unlike PMMA, which was found to degrade by a thermal depolymerization process. The more stable molecular structure of PMMA makes it the most viable thermoplastic polymer for femtosecond laser fabrication of microfluidic channels.

  1. Femtosecond laser ablation of polymeric substrates for the fabrication of microfluidic channels

    Energy Technology Data Exchange (ETDEWEB)

    Suriano, Raffaella, E-mail: raffaella.suriano@chem.polimi.it [Dipartimento di Chimica, Materiali e Ingegneria Chimica ' Giulio Natta' , Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy); Kuznetsov, Arseniy [Laser Zentrum Hannover e.V., Hollerithallee 8, 30419 Hannover (Germany); Eaton, Shane M. [Istituto di Fotonica e Nanotecnologie (IFN)-CNR, Piazza Leonardo da Vinci 32, 20133 Milan (Italy); Kiyan, Roman [Laser Zentrum Hannover e.V., Hollerithallee 8, 30419 Hannover (Germany); Cerullo, Giulio [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy); Osellame, Roberto [Istituto di Fotonica e Nanotecnologie (IFN)-CNR, Piazza Leonardo da Vinci 32, 20133 Milan (Italy); Chichkov, Boris N. [Laser Zentrum Hannover e.V., Hollerithallee 8, 30419 Hannover (Germany); Levi, Marinella; Turri, Stefano [Dipartimento di Chimica, Materiali e Ingegneria Chimica ' Giulio Natta' , Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy)

    2011-05-01

    This manuscript presents a study of physical and chemical properties of microchannels fabricated by femtosecond laser processing technology in thermoplastic polymeric materials, including poly(methyl methacrylate) (PMMA), polystyrene (PS) and cyclic olefin polymer (COP). By surface electron microscopy and optical profilometry, the dimensions of microchannels in the polymers were found to be easily tunable, with surface roughness values comparable to those obtained by standard prototyping techniques such as micromilling. Through colorimetric analysis and optical microscopy, PMMA was found to remain nearly transparent after ablation while COP and PS darkened significantly. Using infrared spectroscopy, the darkening in PS and COP was attributed to significant oxidation and dehydrogenation during laser ablation, unlike PMMA, which was found to degrade by a thermal depolymerization process. The more stable molecular structure of PMMA makes it the most viable thermoplastic polymer for femtosecond laser fabrication of microfluidic channels.

  2. Ablative fractional laser alters biodistribution of ingenol mebutate in the skin

    DEFF Research Database (Denmark)

    Erlendsson, A M; Taudorf, E H; Eriksson, A. H.

    2015-01-01

    Topically applied ingenol mebutate (IngMeb) is approved for field-treatment of actinic keratosis and is currently being investigated for treatment of non-melanoma skin cancer (NMSC). Ablative fractional lasers (AFXLs) generate microscopic ablation zones (MAZs) in the skin, which may help induce...... a deep penetration needed for effective treatment of NMSC. Using Franz diffusion cells, uptake and bio-distribution were investigated over 21 h in intact (n = 9) and AFXL-exposed porcine skin (n = 58). A 2940-nm fractional Er:YAG laser generated intraepidermal (11.2 mJ/MAZ; 66 μm deep, 177 μm wide...... accumulated in SC and epidermis. Uptake depended entirely on laser density; increasing coverage from 0 % to 0.5 %, 1 %, 2.5 %, 5 %, and 10.5 % enhanced dermal uptake 1.6-, 2.1-, 3.1-, 3.4-, and 3.9-fold, respectively (p

  3. Ablation and cone formation mechanism on CR-39 by ArF laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shakeri Jooybari, B., E-mail: baninshakery@gmail.com, E-mail: hafarideh@aut.ac.ir [Department of Energy Engineering and Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Nuclear Science and Technology Research Institute NSRT, Tehran (Iran, Islamic Republic of); Afarideh, H., E-mail: baninshakery@gmail.com, E-mail: hafarideh@aut.ac.ir [Department of Energy Engineering and Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Lamehi-Rachti, M. [Nuclear Science and Technology Research Institute NSRT, Tehran (Iran, Islamic Republic of); Ghergherehchi, M. [Department of Energy Engineering and Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); College of Information and Communication Engineering, Sungkyunkwan University, Suwon (Korea, Republic of)

    2015-03-07

    In this work, chemical properties, surface modification, and micro structures formation on ablated polyallyl di-glycol carbonate (CR-39) polymer by ArF laser irradiation (λ = 193 nm) at various fluences and pulse number were investigated. CR-39 samples have been irradiated with an ArF laser (193 nm) at a repetition rate of 1 Hz. Threshold fluence of ablation and effective absorption coefficient of CR-39 were determined. Conical microstructures (Taylor cone) formed on laser-ablated CR-39 exhibit: smooth, Taylor cone shape walls and sharp tips together with interference and well defined fringe-structure with a period of 230 nm, around cone base. Mechanism of cone formation and cone evolution of CR-39 ablated surface were investigated by change of fluences (at a given pulse number) and pulse number (at a given fluence). Cone height, cone base, and region of interface were increased in micrometer steps by increasing the total fluence. Depression on the base of the cone and the circular fringe were simulated. FTIR spectra were measured and energy dispersive x-ray analysis of irradiated and un-irradiated samples was performed.

  4. Design and fabrication of a chamber for the deposit of thin films by laser ablation

    International Nuclear Information System (INIS)

    Chirino O, S.; Escobar A, I.; Camps C, E.; Garcia E, J.I.

    2000-01-01

    The laser ablation technique is an alternative for the obtention of thin films which is less expensive, more reliable, efficient and with some advantages with respect to conventional processes. On of the most important components which forms a laser ablation system is the vacuum chamber, that has as general purposes the following: a) To carry out studies about plasma such as optical emission spectroscopy and measurements by deflectometry. b) To carry out an In situ monitoring about the film growth through the reflectivity measurements of the combination substrate-film. c) To deposit thin films of different materials such as oxides, carbon, metals, etc. In this work it is showed how the vacuum chamber was designed and made to perform the store of thin films by laser ablation and for characterising the formed plasma as a result of the ablation process. The chamber design was enough versatile that will allow to add it more accessory just making it simple modifications. Its cost was very cheap more or less one twentieth of a commercial chamber. (Author)

  5. Facile and fast synthesis of SnS2 nanoparticles by pulsed laser ablation in liquid

    Science.gov (United States)

    Johny, J.; Sepulveda-Guzman, S.; Krishnan, B.; Avellaneda, D.; Shaji, S.

    2018-03-01

    Nanoparticles (NPs) of tin disulfide (SnS2) were synthesized using pulsed laser ablation in liquid (PLAL) technique. Effects of different liquid media and ablation wavelengths on the morphology and optical properties of the nanoparticles were studied. Nd: YAG laser wavelengths of 532 nm and 1064 nm (frequency 10 Hz and pulse width 10 ns) were used to irradiate SnS2 target immersed in liquid for the synthesis of SnS2 nanoparticles. Here PLAL was a fast synthesis technique, the ablation was only for 30 s. Transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV-vis absorption spectroscopy and photoluminescence spectroscopy were used to characterize the SnS2 NPs. TEM images showed that the liquid medium and laser wavelength influence the morphology of the NPs. SAED patterns and high resolution TEM (HRTEM) images confirmed the crystallinity of the particles. XRD and XPS analyses confirmed that SnS2 NPs were having exact crystalline structure and chemical states as that of the target. Raman analysis also supported the results obtained by XRD and XPS. Optical band gaps of the nanocolloids evaluated from their UV-vis absorption spectra were 2.4-3.05 eV. SnS2 NPs were having luminescence spectra in the blue-green region irrespective of the liquid media and ablation wavelength.

  6. Preparation of silver nanoparticles in virgin coconut oil using laser ablation

    Directory of Open Access Journals (Sweden)

    Reza Zamiri,B Z Azmi. Amir Reza Sadrolhosseini

    2011-01-01

    Full Text Available Reza Zamiri1, B Z Azmi1,2, Amir Reza Sadrolhosseini1, Hossein Abbastabar Ahangar3, A W Zaidan1, M A Mahdi41Department of Physics, 2Advanced Materials and Nanotechnology Laboratory, 3Department of Chemistry, 4Wireless and Photonics Networks Research Center, Universiti Putra Malaysia, Serdang, Selangor, MalaysiaAbstract: Laser ablation of a silver plate immersed in virgin coconut oil was carried out for fabrication of silver nanoparticles. A Nd:YAG laser at wavelengths of 1064 nm was used for ablation of the plate at different times. The virgin coconut oil allowed formation of nanoparticles with well-dispersed, uniform particle diameters that were stable for a reasonable length of time. The particle sizes and volume fraction of nanoparticles inside the solutions obtained at 15, 30, 45 min ablation times were 4.84, 5.18, 6.33 nm and 1.0 × 10-8, 1.6 × 10-8, 2.4 × 10-8, respectively. The presented method for preparation of silver nanoparticles in virgin coconut oil is environmentally friendly and may be considered a green method.Keywords: silver nanoparticles, laser ablation, virgin coconut oil

  7. Three-Dimensional Numerical Analysis for Posture Stability of Laser Propulsion Vehicle

    Science.gov (United States)

    Takahashi, Masayuki; Ohnishi, Naofumi

    2011-11-01

    We have developed a three-dimensional hydrodynamics code coupling equation of motion of a rigid body for analyzing posture stability of laser propulsion vehicle through numerical simulations of flowfield interacting with unsteady motion of the vehicle. Asymmetric energy distribution is initially added around the focal spot (ring) in order to examine posture stability against an asymmetric blast wave resulting from a laser offset for a lightcraft-type vehicle. The vehicle moves to cancel out the offset from initial offset. However, the Euler angle grows and never returns to zero in a time scale of laser pulse. Also, we found that the vehicle moves to cancel tipping angle when the laser is irradiated to the vehicle with initial tipping angle over the wide angle range, through the vehicle cannot get sufficient restoring force in particular angle, and the tipping angle does not decrease from the initial value for that case.

  8. [Delivery of megawatts high energy laser pulse with large core diameter silica fiber and its application in dual-wavelength laser-ablation laser-induced breakdown spectroscopy].

    Science.gov (United States)

    Zhou, Qi; Peng, Fei-Fei; Li, Run-Hua; Chen, Yu-Qi; Yang, Xue-Jiao

    2013-12-01

    To resolve the contradiction between spatial resolution and analysis sensitivity in single pulse laser-induced breakdown spectroscopy (LIBS), a study on dual-wavelength laser-ablation laser-induced breakdown spectroscopy (LA-LIBS) was carried out by using one Nd : YAG laser which was capable of two laser beam outputs with different wavelengths, where, the second harmonic output, 532 nm laser beam, was used as laser-ablation source, and the fundamental output, 1064 nm laser beam, was delivered with a large core diameter silica fiber to realize nanoseconds time-delay and then used to breakdown the ablated samples. Two laser beams were orthogonally arranged to realize element analysis with high spatial resolution and high sensitivity. Some key techniques on the coupling of 1064 nm laser beam into fiber, the collimation of laser at the fiber end and re-focusing of the laser beam were studied. The energy delivery capabilities of four fibers of different types were studied and the maximum values were determined experimentally. A Q-switched laser pulse with 15 mJ pulse energy was successfully delivered by selecting a 50 meter long silica fiber with 800 microm core diameter and 0. 39 numerical aperture. And 250 ns time-delay was realized. A copper alloy was analyzed by spectra with current established LA-LIBS system and the possibility of realizing dual-wavelength LA-LIBS analysis based on one Nd : YAG laser was demonstrated experimentally. In this technique, only one Nd: YAG laser was required to carry out spectral analysis. It has a few advantages, such as simple equipment structure, and being convenient to miniaturize the whole system etc. This dual-wavelength LA-LIBS technique was suitable for in-situ elements microanalysis for different samples with both high spatial resolution and high sensitivity.

  9. Monitoring of the morphologic reconstruction of deposited ablation products in laser irradiation of silicon

    Directory of Open Access Journals (Sweden)

    Vlasova M.

    2008-01-01

    Full Text Available Using electron microscopy, atomic force microscopy, X-ray microanalysis, and IR spectroscopy, it was established that, in the regime of continuous laser irradiation of silicon at P = 170 W in different gaseous atmospheres with an oxygen impurity, SiOx composite films with a complex morphology form. The main components of ablation products are clusters that form during flight of ablation products and as a result of separation of SiOx-clusters from the zone of the irradiation channel. The roughness and density of the films depend on the heating temperature of the target surface and the type of deposited clusters.

  10. Preparation of CuO nanoparticles by laser ablation in liquid

    Energy Technology Data Exchange (ETDEWEB)

    Abdulateef, Sinan A., E-mail: sinan1974@yahoo.com; MatJafri, M. Z.; Omar, A. F., E-mail: thinker-academy@yahoo.com; Ahmed, Naser M.; Azzez, Shrook A. [School of Physics, USM, 11800 Penang (Malaysia); Ibrahim, Issam M. [Baghdad university, physics department (Iraq); Al-Jumaili, Batool E. B. [Department of Physics, (UPM), Serdang, Selangor 43400 (Malaysia)

    2016-07-06

    Colloidal Cu nanoparticles (NPs) were synthesized by pulsed Nd:YAG laser ablation in acetone. Cu NPs were converted into CuO. The size and optical properties of these NPs were characterized using an UV/Vis spectrophotometer, transmission electron microscopy, and X-ray diffraction. Cu NPs were spherical, and their mean diameter in acetone was 8 nm–10 nm. Optical extinction immediately after the ablation showed surface Plasmon resonance peaks at 602 nm. The color of Cu NPs in acetone was green and stable even after a long time.

  11. Optical Nonlinear Refractive Index of Laser-Ablated Gold Nanoparticles Graphene Oxide Composite

    OpenAIRE

    Amir Reza Sadrolhosseini; A. S. M. Noor; Nastaran Faraji; Alireza Kharazmi; Mohd. Adzir Mahdi

    2014-01-01

    Gold nanoparticles were prepared in graphene oxide using laser ablation technique. The ablation times were varied from 10 to 40 minutes, and the particle size was decreased from 16.55 nm to 5.18 nm in spherical shape. The nanoparticles were capped with carboxyl and the hydroxyl groups were obtained from Fourier transform infrared spectroscopy. Furthermore, the UV-visible peak shifted with decreasing of nanoparticles size, appearing from 528 nm to 510 nm. The Z-scan technique was used to measu...

  12. Evaporation as a diagnostic test for hydrodynamic cooling of laser-ablated clusters

    International Nuclear Information System (INIS)

    Klots, C.E.

    1991-01-01

    The properties of materials laser-ablated from a surface are of considerable interest. The interrogation of these properties inevitably occurs at a point some distance from the surface. One might then ask what processes have occurred in the intervening path length. Immediately, for example, one wonders whether the material was released as such from the surface or was formed as a result of collisions at a distant point. Similarly, one might ask if an observed ''temperature'' of the materials is characteristic of the ablation process of of subsequent events. We will indicate here how measurements of metastable evaporation rates can provide clues which are pertinent to these questions. 7 refs

  13. Spatio-temporal mapping of ablated species in ultrafast laser-produced graphite plasmas

    International Nuclear Information System (INIS)

    Al-Shboul, K. F.; Harilal, S. S.; Hassanein, A.

    2012-01-01

    We studied the spatial and temporal distributions of ionic, neutral, and molecular species generated by femtosecond laser produced plasma under varying ambient nitrogen gas pressures. Plasmas were generated by irradiating planar graphite targets using 40 fs pulses of 800 nm radiation from a Ti:Sapphire laser. The results show that in the presence of an ambient gas, the molecular species spatial extension and lifetime are directly correlated to the evolution of excited ions. The present studies also provide valuable insights into the evolution history of various species and their excitation during ultrafast laser ablation.

  14. Non-monotonic variation of Au nanoparticle yield during femtosecond/picosecond laser ablation in water

    Science.gov (United States)

    Danilov, P. A.; Ionin, A. A.; Kudryashov, S. I.; Rudenko, A. A.; Saraeva, I. N.; Zayarny, D. A.

    2017-05-01

    Ablative multi-shot preparation of gold nanoparticle hydrosols was carried out by raster-scanning a gold plate in deionized water using focused 1030 nm laser pulses of variable pulse width (0.3-6 ps). The relative nanoparticle yield, correlated with the extinction coefficient of colloidal solutions, exhibited an extraordinary non-monotonic variation versus the laser pulse width, which is explained by the electronic dynamics in gold in the lower limit, and either film water boiling or sub-critical peak laser powers in the upper limit.

  15. Modelling the formation of nanostructures on metal surface induced by femtosecond laser ablation

    International Nuclear Information System (INIS)

    Djouder, M.; Itina, T.E.; Deghiche, D.; Lamrous, O.

    2012-01-01

    We employ the particle-in-cell method to simulate the mechanisms of femtosecond (fs) laser interactions with a metallic target. The theoretical approach considers the solid as a gas of free electrons in a lattice of immobile ions and the laser fluences close to the ablation threshold. At first moments of the interaction, our simulations mapped out different nanostructures. We carefully characterized the rippling phase and found that its morphology is dependent on the distribution of the electron density and the period of the ripples depends on the laser intensity. The simulation method provides new insights into the mechanisms that are responsible for surface grating formation.

  16. Modelling the formation of nanostructures on metal surface induced by femtosecond laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Djouder, M. [Laboratoire de Physique et Chimie Quantique, Universite Mouloud Mammeri de Tizi-ouzou, BP 17 RP, 15000 Tizi-Ouzou (Algeria); Itina, T.E. [Laboratoire Hubert Curien, UMR CNRS 5516/Universite Jean Monnet, 18 rue de Professeur Benoit Lauras, 42000 Saint-Etienne (France); Deghiche, D. [Laboratoire de Physique et Chimie Quantique, Universite Mouloud Mammeri de Tizi-ouzou, BP 17 RP, 15000 Tizi-Ouzou (Algeria); Lamrous, O., E-mail: omarlamrous@mail.ummto.dz [Laboratoire de Physique et Chimie Quantique, Universite Mouloud Mammeri de Tizi-ouzou, BP 17 RP, 15000 Tizi-Ouzou (Algeria)

    2012-01-15

    We employ the particle-in-cell method to simulate the mechanisms of femtosecond (fs) laser interactions with a metallic target. The theoretical approach considers the solid as a gas of free electrons in a lattice of immobile ions and the laser fluences close to the ablation threshold. At first moments of the interaction, our simulations mapped out different nanostructures. We carefully characterized the rippling phase and found that its morphology is dependent on the distribution of the electron density and the period of the ripples depends on the laser intensity. The simulation method provides new insights into the mechanisms that are responsible for surface grating formation.

  17. Ablation and transmission of thin solid targets irradiated by intense extreme ultraviolet laser radiation

    Directory of Open Access Journals (Sweden)

    V. Aslanyan

    2016-09-01

    Full Text Available The interaction of an extreme ultraviolet (EUV laser beam with a parylene foil was studied by experiments and simulation. A single EUV laser pulse of nanosecond duration focused to an intensity of 3 × 1010 W cm−2 perforated micrometer thick targets. The same laser pulse was simultaneously used to diagnose the interaction by a transmission measurement. A combination of 2-dimensional radiation-hydrodynamic and diffraction calculations was used to model the ablation, leading to good agreement with experiment. This theoretical approach allows predictive modelling of the interaction with matter of intense EUV beams over a broad range of parameters.

  18. Ablation of brain by erbium laser: study of dynamic behavior and tissue damage

    Science.gov (United States)

    Cubeddu, Rinaldo; Sozzi, C.; Taroni, Paola; Valentini, Gianluca; Bottiroli, Giovanni F.; Croce, Anna C.

    1994-02-01

    In this work two aspects of the ablation of brain by Erbium laser have been mainly addressed: the time evolution of the phenomenon and the damages, both thermal and mechanical, produced in the tissues. The time resolved images acquired during the laser interaction revealed that deep lacerations develop in the tissue due to a mechanical stress. The damages have been evaluated by studying the changes in the autofluorescence emission properties and the reduction in enzymatic activities (NADH Oxidase and ATPase). The results obtained in this study indicate that the thermal alterations resulting from the exposure to Erbium laser are limited, whereas the mechanical damages can be very pronounced.

  19. Selective ablation of photovoltaic materials with UV laser sources for monolithic interconnection of devices based on a-Si:H

    Energy Technology Data Exchange (ETDEWEB)

    Molpeceres, C. [Centro Laser UPM, Univ. Politecnica de Madrid, Crta. de Valencia Km 7.3, 28031 Madrid (Spain)], E-mail: carlos.molpeceres@upm.es; Lauzurica, S.; Garcia-Ballesteros, J.J.; Morales, M.; Guadano, G.; Ocana, J.L. [Centro Laser UPM, Univ. Politecnica de Madrid, Crta. de Valencia Km 7.3, 28031 Madrid (Spain); Fernandez, S.; Gandia, J.J. [Dept. de Energias Renovables, Energia Solar Fotovoltaica, CIEMAT, Avda, Complutense 22, 28040 Madrid (Spain); Villar, F.; Nos, O.; Bertomeu, J. [CeRMAE Dept. Fisica Aplicada i Optica, Universitat de Barcelona, Av. Diagonal 647, 08028 Barcelona (Spain)

    2009-03-15

    Lasers are essential tools for cell isolation and monolithic interconnection in thin-film-silicon photovoltaic technologies. Laser ablation of transparent conductive oxides (TCOs), amorphous silicon structures and back contact removal are standard processes in industry for monolithic device interconnection. However, material ablation with minimum debris and small heat affected zone is one of the main difficulty is to achieve, to reduce costs and to improve device efficiency. In this paper we present recent results in laser ablation of photovoltaic materials using excimer and UV wavelengths of diode-pumped solid-state (DPSS) laser sources. We discuss results concerning UV ablation of different TCO and thin-film silicon (a-Si:H and nc-Si:H), focussing our study on ablation threshold measurements and process-quality assessment using advanced optical microscopy techniques. In that way we show the advantages of using UV wavelengths for minimizing the characteristic material thermal affection of laser irradiation in the ns regime at higher wavelengths. Additionally we include preliminary results of selective ablation of film on film structures irradiating from the film side (direct writing configuration) including the problem of selective ablation of ZnO films on a-Si:H layers. In that way we demonstrate the potential use of UV wavelengths of fully commercial laser sources as an alternative to standard backscribing process in device fabrication.

  20. Selective ablation of photovoltaic materials with UV laser sources for monolithic interconnection of devices based on a-Si:H

    International Nuclear Information System (INIS)

    Molpeceres, C.; Lauzurica, S.; Garcia-Ballesteros, J.J.; Morales, M.; Guadano, G.; Ocana, J.L.; Fernandez, S.; Gandia, J.J.; Villar, F.; Nos, O.; Bertomeu, J.

    2009-01-01

    Lasers are essential tools for cell isolation and monolithic interconnection in thin-film-silicon photovoltaic technologies. Laser ablation of transparent conductive oxides (TCOs), amorphous silicon structures and back contact removal are standard processes in industry for monolithic device interconnection. However, material ablation with minimum debris and small heat affected zone is one of the main difficulty is to achieve, to reduce costs and to improve device efficiency. In this paper we present recent results in laser ablation of photovoltaic materials using excimer and UV wavelengths of diode-pumped solid-state (DPSS) laser sources. We discuss results concerning UV ablation of different TCO and thin-film silicon (a-Si:H and nc-Si:H), focussing our study on ablation threshold measurements and process-quality assessment using advanced optical microscopy techniques. In that way we show the advantages of using UV wavelengths for minimizing the characteristic material thermal affection of laser irradiation in the ns regime at higher wavelengths. Additionally we include preliminary results of selective ablation of film on film structures irradiating from the film side (direct writing configuration) including the problem of selective ablation of ZnO films on a-Si:H layers. In that way we demonstrate the potential use of UV wavelengths of fully commercial laser sources as an alternative to standard backscribing process in device fabrication.

  1. Pascal panretinal laser ablation and regression analysis in proliferative diabetic retinopathy: Manchester Pascal Study Report 4.

    Science.gov (United States)

    Muqit, M M K; Marcellino, G R; Henson, D B; Young, L B; Turner, G S; Stanga, P E

    2011-11-01

    To quantify the 20-ms Pattern Scan Laser (Pascal) panretinal laser photocoagulation (PRP) ablation dosage required for regression of proliferative diabetic retinopathy (PDR), and to explore factors related to long-term regression. We retrospectively studied a cohort of patients who participated in a randomised clinical trial, the Manchester Pascal Study. In all, 36 eyes of 22 patients were investigated over a follow-up period of 18 months. Primary outcome measures included visual acuity (VA) and complete PDR regression. Secondary outcomes included laser burn dosimetry, calculation of retinal PRP ablation areas, and effect of patient-related factors on disease regression. A PDR subgroup analysis was undertaken to assess all factors related to PDR regression according to disease severity. There were no significant changes in logMAR VA for any group over time. In total, 10 eyes (28%) regressed after a single PRP. Following top-up PRP treatment, regression rates varied according to severity: 75% for mild PDR (n=6), 67% for moderate PDR (n=14), and 43% in severe PDR (n=3). To achieve complete disease regression, mild PDR required a mean of 2187 PRP burns and 264 mm(2) ablation area, moderate PDR required 3998 PRP burns and area 456 mm(2), and severe PDR needed 6924 PRP laser burns (836 mm(2); P<0.05). Multiple 20-ms PRP treatments applied over time does not adversely affect visual outcomes, with favourable PDR regression rates and minimal laser burn expansion over 18 months. The average laser dosimetry and retinal ablation areas to achieve complete regression increased significantly with worsening PDR.

  2. Static and Hypersonic Experimental Analysis of Impulse Generation in Air-Breathing Laser-Thermal Propulsion

    Science.gov (United States)

    Salvador, Israel Irone

    The present research campaign centered on static and hypersonic experiments performed with a two-dimensional, repetitively-pulsed (RP) laser Lightcraft model. The future application of interest for this basic research endeavor is the laser launch of nano- and micro-satellites (i.e., 1-100 kg payloads) into Low Earth Orbit (LEO), at low-cost and "on-demand". This research began with an international collaboration on Beamed Energy Propulsion between the United States Air Force and Brazilian Air Force to conduct experiments at the Henry T. Nagamatsu Laboratory of Aerothermodynamics and Hypersonics (HTN-LAH). The laser propulsion (LP) experiments employed the T3 Hypersonic Shock Tunnel (HST), integrated with twin gigawatt pulsed Lumonics 620-TEA CO2 lasers to produce the required test conditions. Following an introduction of the pulsed laser thermal propulsion concept and a state-of-the-art review of the topic, the principal physical processes are outlined starting from the onset of the laser pulse and subsequent laser-induced air-breakdown, to the expansion and exhaust of the resulting blast wave. After installation of the 254 mm wide, 2D Lightcraft model into the T3 tunnel, static LP tests were performed under quiescent (no-flow) conditions at ambient pressures of 0.06, 0.15, 0.3 and 1 bar, using the T3 test-section/dump-tank as a vacuum chamber. Time-dependent surface pressure distributions were measured over the engine thrust-generating surfaces following laser energy deposition; the delivered impulse and momentum coupling coefficients (Cm) were calculated from that pressure data. A Schlieren visualization system (using a high-speed Cordin digital camera) captured the laser breakdown and blast wave expansion process. The 2D model's Cm performance of 600 to 3000 N/MW was 2.5-5x higher than theoretical projections available in the literature, but indeed in the realm of feasibility for static conditions. Also, these Cm values exceed that for smaller Lightcraft models

  3. Histological evaluation of vertical laser channels from ablative fractional resurfacing

    DEFF Research Database (Denmark)

    Skovbølling Haak, Christina; Illes, Monica; Paasch, Uwe

    2011-01-01

    and efficient treatment outcome. The aim of this study was to establish a standard model to document the histological tissue damage profiles after AFR and to test a new laser device at diverse settings. Ex vivo abdominal pig skin was treated with a MedArt 620, prototype fractional carbon dioxide (CO(2)) laser...

  4. Acceleration of polyethelene foils by laser driven ablation

    International Nuclear Information System (INIS)

    Ahlstrom, H.G.; Burginyon, G.A.; Haas, R.A.

    1974-01-01

    The production of thermonuclear energy, by laser driven implosion of spherical DT shells, with achievable laser technology, requires the development of an efficient and stable implosion. Certain aspects of the acceleration of the spherical shells can be studied experimentally by irradiating thin, 5 to 25 μm, polyethelene foils. The results of foil acceleration experiments performed using a Nd:YAG-Glass laser capable of producing 150 J, 1 nsec pulses will be discussed. The dynamics of the accelerated foil, the ion blow off, high energy electron spectrum (6 to 180 keV), x-ray spectrum (1 to 150 keV) the spatial distribution of the x-ray emission, the laser beam focal spot energy distribution, the laser temporal pulse shape and spectrum for reflected and transmitted radiation have all been measured simultaneously. The results of these measurements are compared with detailed numerical simulations. (U.S.)

  5. Novel endoscopic application of a new flexible-fiber CO2 laser for esophageal mucosal ablation in a porcine model.

    Science.gov (United States)

    Anandasabapathy, S; Maru, D; Klumpp, S; Uthamanthil, R; Borne, A; Bhutani, M S

    2009-02-01

    The CO (2) laser is a surgical tool that is widely used because of its predictable penetration depth and minimal collateral damage due to efficient absorption of CO (2) laser energy by tissue water. Until recently, endoscopic use was limited by lack of an efficient, flexible delivery system. The aim of the current study was to evaluate the performance, efficacy, and safety of a novel, photonic band-gap CO (2) laser configured for esophageal mucosal ablation. This was an endoscopic experimental study in a porcine survival model. Initial evaluation was done on ex vivo tissue followed by endoscopic studies at 7-, 10-, 15-, and 20-W power and at 0-, 1-, 2-, 5-, and 10-mm distances, using continuous and pulsed currents, to determine optimal performance settings. In an IACUC-approved protocol, six pigs underwent circumferential ablation of the distal 6 cm of the esophagus at 10W continuous current. The animals were monitored for 2 or 4 weeks to evaluate delayed effects. Prior to euthanasia, the proximal esophagus was ablated to evaluate the homogeneity of ablation and depth of injury immediately after single and repeat ablation. The animals resumed normal diets within 24 hours and experienced no dysphagia or weight loss. Pathology at 2 and 4 weeks revealed complete re-epithelialization with minimal histologic injury. A single application of the laser produced complete transepithelial ablation of a mean of 83.3 % of the surface area (range 55 % - 100 %); depth of injury was to the muscularis mucosa in five pigs and to the superficial submucosa in one pig. With ablation, sloughing, and re-ablation, a mean of 95 % transepithelial ablation was achieved (range 80 % -100 %) with similar depth of injury. Using a novel, flexible CO (2) laser, homogeneous ablation was achieved with predictable penetration and minimal deep tissue injury. These results warrant further evaluation of the laser in Barrett's esophagus, as it may overcome the limitations of current technologies

  6. Characterization of Ag and Au nanoparticles created by nanosecond pulsed laser ablation in double distilled water

    Energy Technology Data Exchange (ETDEWEB)

    Nikolov, A.S., E-mail: anastas_nikolov@abv.bg [Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko shousse 72, Sofia 1784 (Bulgaria); Nedyalkov, N.N.; Nikov, R.G.; Atanasov, P.A. [Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko shousse 72, Sofia 1784 (Bulgaria); Alexandrov, M.T. [Institute of Experimental Pathology and Parasitology, Bulgarian Academy of Sciences, G. Bonchev Street, bl. 25, Sofia 1113 (Bulgaria)

    2011-04-01

    Pulsed laser ablation of Ag and Au targets, immersed in double-distilled water is used to synthesize metallic nanoparticles (NPs). The targets are irradiated for 20 min by laser pulses at different wavelengths-the fundamental and the second harmonic (SHG) ({lambda} = 1064 and 532 nm, respectively) of a Nd:YAG laser system. The ablation process is performed at a repetition rate of 10 Hz and with pulse duration of 15 ns. Two boundary values of the laser fluence for each wavelength under the experimental conditions chosen were used-it varied from several J/cm{sup 2} to tens of J/cm{sup 2}. Only as-prepared samples were measured not later than two hours after fabrication. The NPs shape and size distribution were evaluated from transmission electron microscopy (TEM) images. The suspensions obtained were investigated by optical transmission spectroscopy in the near UV and in the visible region in order to get information about these parameters. Spherical shape of the NPs at the low laser fluence and appearance of aggregation and building of nanowires at the SHG and high laser fluence was seen. Dependence of the mean particle size at the SHG on the laser fluence was established. Comments on the results obtained have been also presented.

  7. Laser Guidance in C-Arm Cone-Beam CT-Guided Radiofrequency Ablation of Osteoid Osteoma Reduces Fluoroscopy Time

    NARCIS (Netherlands)

    Kroes, M.W.; Busser, W.M.H.; Hoogeveen, Y.L.; Lange, F. de; Schultze Kool, L.J.

    2017-01-01

    PURPOSE: To assess whether laser guidance can reduce fluoroscopy and procedure time of cone-beam computed tomography (CBCT)-guided radiofrequency (RF) ablations of osteoid osteoma compared to freehand CBCT guidance. MATERIALS AND METHODS: 32 RF ablations were retrospectively analyzed, 17

  8. In vitro investigations of propulsion during laser lithotripsy using video tracking.

    Science.gov (United States)

    Eisel, Maximilian; Ströbl, Stephan; Pongratz, Thomas; Strittmatter, Frank; Sroka, Ronald

    2017-12-20

    Ureteroscopic laser lithotripsy is an important and widely used method for destroying ureter stones. It represents an alternative to ultrasonic and pneumatic lithotripsy techniques. Although these techniques have been thoroughly investigated, the influence of some physical parameters that may be relevant to further improve the treatment results is not fully understood. One crucial topic is the propulsive stone movement induced by the applied laser pulses. To simplify and speed up the optimization of laser parameters in this regard, a video tracking method was developed in connection with a vertical column setup that allows recording and subsequently analyzing the propulsive stone movement in dependence of different laser parameters in a particularly convenient and fast manner. Pulsed laser light was applied from below to a cubic BegoStone phantom loosely guided within a vertical column setup. The video tracking method uses an algorithm to determine the vertical stone position in each frame of the recorded scene. The time-dependence of the vertical stone position is characterized by an irregular series of peaks. By analyzing the slopes of the peaks in this signal it was possible to determine the mean upward stone velocity for a whole pulse train and to compare it for different laser settings. For a proof of principle of the video tracking method, a specific pulse energy setting (1 J/pulse) was used in combination with three different pulse durations: short pulse (0.3 ms), medium pulse (0.6 ms), and long pulse (1.0 ms). The three pulse durations were compared in terms of their influence on the propulsive stone movement in terms of upward velocity. Furthermore, the propulsions induced by two different pulse energy settings (0.8 J/pulse and 1.2 J/pulse) for a fixed pulse duration (0.3 ms) were compared. A pulse repetition rate of 10 Hz was chosen for all experiments, and for each laser setting, the experiment was repeated on 15 different freshly

  9. Matrix-Independent Calibration of Laser Ablation Microanalysis by High Resolution ICP- MS

    Science.gov (United States)

    Gaboardi, M.; Humayun, M.

    2008-05-01

    The combination of laser ablation and inductively coupled plasma mass spectrometry (LA-ICPMS) allows for rapid chemical analysis of solid samples at high spatial resolution. Calibration of the technique is limited by the small number of reliable standards available and by the diversity of solid matrices, including silicates, oxides, sulfides, carbonates, metals, etc. The situation is best for silicate glasses, for which both USGS standards and MPI-DING glass standards are available spanning a wide range of silica content. In laser ablation, the laser produces an aerosol that is ionized by the argon plasma source, so that ionization efficiency depends primarily on the plasma and not on the ablation process. Thus, internally standardized measurements by laser ablation should, in principle, be insensitive to matrix composition. Concerns about the necessity for sample-standard matrix matching have previously limited the possible quantitative applications of the method, but the necessity of matrix matching has not been previously studied in detail. We will present the results of a detailed study of matrix- dependence on inter-calibration of a broad range of elements in silicate, sulfide, metal and aqueous matrices, using a UP213 (213 nm) laser ablation system coupled to high resolution ICP-MS (Element1 and Element XR). We define a relative sensitivity factor (RSF) for each element which, when multiplied by the ion intensity ratio, yields a concentration ratio to an internal standard element. This study documents that the RSFs for practically all elements with a First Ionization Potential (FIP) below 8 ev are matrix-independent. The calibration of laser ablation analysis of such elements can be performed using aqueous or desolvated aqueous standards. Finally, using the faraday cup detector of an Element XR, we examine the influence of the measured oxygen and argon ion intensities on the RSFs of other elements. We find that as the oxygen ion to argon ion ratio increases

  10. Large volume ablation of Sapphire with ultra-short laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Shamir, A., E-mail: shamirav@post.bgu.ac.il [Department of Electrical and Computer Engineering, Ben-Gurion University of the Negev, P.O.B. 653, Beer-Sheva 84105 (Israel); Electro-optics Unit, Ben-Gurion University of the Negev, P.O.B. 653, Beer-Sheva 84105 (Israel); Ishaaya, A.A. [Department of Electrical and Computer Engineering, Ben-Gurion University of the Negev, P.O.B. 653, Beer-Sheva 84105 (Israel)

    2013-04-01

    The superior optical and mechanical properties of Sapphire (Al{sub 2}O{sub 3}) are highly desirable in various opto-electronics and micro-mechanical applications. However, Sapphire's intrinsic hardness and resistance to most chemicals result in significant processing difficulties. Laser micro-machining is emerging as a promising technology, in particular, the use of ultra-short pulses for material ablation. In this work we investigate and characterize experimentally large volume ablation of Sapphire with femtosecond pulses, and compare the results to previously reported drilling and cutting experiments. We manage to identify optimized parameters for overcoming deleterious thermal effects and debris scattering, and demonstrate high quality 180 μm-deep ablation of 1 mm × 15 mm area in Sapphire.

  11. Plasma ignition thresholds in UV laser ablation plumes

    Science.gov (United States)

    Clarke, P.; Dyer, P. E.; Key, P. H.; Snelling, H. V.

    Ultraviolet (UV) laser thresholds for plasma ignition on solid targets predicted from electron-neutral collisional heating are generally much higher than those observed experimentally. This inconsistency was reconciled by Rosen, et al. [2], who showed that excited-state photoionization played a key role in long-pulse UV laser breakdown. Here we develop a related model but with emphasis on pulses of 10 ns duration. Experimental results are also reported for titanium, copper, silicon, and ferulic acid targets in vacuum, irradiated with combinations of the XeF, KrF, and ArF lasers for comparison with predictions.

  12. Processing condition influence on the characteristics of gold nanoparticles produced by pulsed laser ablation in liquids

    Energy Technology Data Exchange (ETDEWEB)

    Nikov, R.G., E-mail: rosen_nikov@abv.bg [Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko Chaussee 72, Sofia 1784 (Bulgaria); Nikolov, A.S.; Nedyalkov, N.N.; Atanasov, P.A. [Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko Chaussee 72, Sofia 1784 (Bulgaria); Alexandrov, M.T. [Institute of Experimental Pathology and Parasitology, Bulgarian Academy of Sciences, G. Bonchev Street, Building 25, Sofia 1113 (Bulgaria); Karashanova, D.B. [Institute of Optical Materials and Technologies, Bulgarian Academy of Sciences, G. Bonchev Street, Building 109, Sofia 1113 (Bulgaria)

    2013-06-01

    A study is presented of Au nanoparticles (NPs) created by nanosecond pulsed laser ablation of a solid target in double distilled water. The influence was examined of the laser wavelength on the size, shape and optical properties of the resulting NPs. Three different wavelengths: the fundamental (λ = 1064 nm), second (λ{sub SHG} = 532) and third (λ{sub THG} = 355) harmonic of a Nd:YAG laser at the same fluence were utilized to produce various colloids. Ablation at the wavelength of 532 nm was investigated in more detail to reveal the influence of self-absorption by the already created NPs on their characteristics. The colloid produced was irradiated by λ{sub irrad} = 532 nm (laser energy 40 mJ) at different times up to 25 min after the end of ablation. The initial structure of welded NPs forming wires was modified. Transmission electron microscopy and optical transmission measurements were used to evaluate the shape and size distribution of the NPs.

  13. Effect of liquid environment on the titanium surface modification by laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Nisar, E-mail: chnisarali@gmail.com [Laser Laboratories, Institute for Applied Physics, Vienna University of Technology, 1040 Vienna (Austria); Department of Basic Science and Humanities, University of Engineering and Technology Lahore, Faisalabad Campus, Faisalabad (Pakistan); Laser Laboratories, Centre for Advanced Studies in Physics, GC University, 1-Church Road, Lahore (Pakistan); Department of Physics, GC University, Kachehri Road, Lahore (Pakistan); Bashir, Shazia [Laser Laboratories, Centre for Advanced Studies in Physics, GC University, 1-Church Road, Lahore (Pakistan); Umm-i-Kalsoom [Laser Laboratories, Institute for Applied Physics, Vienna University of Technology, 1040 Vienna (Austria); Laser Laboratories, Centre for Advanced Studies in Physics, GC University, 1-Church Road, Lahore (Pakistan); Department of Physics, GC University, Kachehri Road, Lahore (Pakistan); Department of Basic Science and Humanities, University of Engineering and Technology Lahore, Kala Shah Kaku Campus, Lahore (Pakistan); Begum, Narjis [Department of Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan); Rafique, Muhammad Shahid [Department of Physics, University of Engineering and Technology Lahore (Pakistan); Husinsky, Wolfgang [Laser Laboratories, Institute for Applied Physics, Vienna University of Technology, 1040 Vienna (Austria)

    2017-05-31

    Highlights: • Liquid assisted ablation effects on the titanium under varying number of laser pulses is investigated. • SEM analysis reveals the growth of various features like ripples, dendritic structures, pores, grains and craters. • Raman and XRD analyses shows the presence of TiO{sub 2} & TiH in both media whereas, TiC, TiCxOy are only identified in propanol. • Hardness of ablated Ti explored by Nano indentation is found to decrease with increasing number of pulses in both media. • Relationship between surface, structural and mechanical modifications is established. - Abstract: The effect of liquid environment (de-ionized water and propanol) on surface, structural and mechanical properties of femtosecond laser ablated titanium has been investigated. For this purpose, Ti: sapphire laser (800 nm, 30 fs, 1 kHz) has been employed, at a fluence of 3.6 J/cm{sup 2} in ambient environments of de-ionized water, and propanol for various number of laser pulses i.e. 500, 1000, 1500 and 2000. The surface features, chemical composition, structural analysis and mechanical properties of irradiated targets have been evaluated by using Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), X -ray Diffraction (XRD), Raman Spectroscopy and Nano-hardness tester. Various features like dendritic structures, globules, porous granular morphology, cones, crater, circular ripples and thermal stress cracking are observed at the ablated area after irradiation. These features are instigated by various thermal and chemical phenomena induced by laser heating at the solid–liquid interface. Decrease in nano-hardness observed in both ambient environments is attributable to the formation of hydrides after irradiation in both media.

  14. "Common" lead isotopic measurements in silicate glasses and minerals by laser ablation double-focusing SC-ICPMS (2017)

    Data.gov (United States)

    Department of the Interior — This dataset is related to a 2017 journal article by A. J. Pietruszka and L. A. Neymark titled "Evaluation of laser ablation double-focusing SC-ICPMS for “common”...

  15. One-step synthesis of Zn/ZnO hollow nanoparticles by the laser ablation in liquid technique

    International Nuclear Information System (INIS)

    Desarkar, H S; Kumbhakar, P; Mitra, A K

    2013-01-01

    Here, one-step synthesis of Zn/ZnO hollow nanoparticles along with solid nanoparticles is reported using the laser ablation in liquid (LAL) technique. Laser radiation of the 1064 nm wavelength is emitted from a Q-switched Nd:YAG laser and is incident on a solid zinc target kept in a water medium. The as-obtained hollow and solid particles are characterized by transmission electron microscopy (TEM) and UV–visible absorption spectroscopy. Hollow nanoparticles are produced by the laser generated bubbles produced in water. The surface of a hollow nanoparticle is assembled from smaller solid nanoparticles. A strong laser–particle interaction is also observed when laser ablation is carried out for a longer time duration. Photoluminescence (PL) emission measurements at room temperature show that all samples exhibit PL emission in the UV–visible region. A reduction in size and an increase in concentration of the synthesized nanoparticles is observed with increasing laser ablation time. (letter)

  16. Comparison of ultraviolet femtosecond and nanosecond laser ablation inductively coupled plasma mass spectrometry analysis in glass, monazite, and zircon.

    Science.gov (United States)

    Poitrasson, Franck; Mao, Xianglei; Mao, Samuel S; Freydier, Rémi; Russo, Richard E

    2003-11-15

    We compared the analytical performance of ultraviolet femtosecond and nanosecond laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). The benefit of ultrafast lasers was evaluated regarding thermal-induced chemical fractionation, that is otherwise well known to limit LA-ICPMS. Both lasers had a Gaussian beam energy profile and were tested using the same ablation system and ICPMS analyzer. Resulting crater morphologies and analytical signals showed more straightforward femtosecond laser ablation processes, with minimal thermal effects. Despite a less stable energy output, the ultrafast laser yielded elemental (Pb/U, Pb/Th) and Pb isotopic ratios that were more precise, repeatable, and accurate, even when compared to the best analytical conditions for the nanosecond laser. Measurements on NIST glasses, monazites, and zircon also showed that femtosecond LA-ICPMS calibration was less matrix-matched dependent and therefore more versatile.

  17. Characterization, diagnosis and ablation of human teeth using blue laser at 457 nm

    Science.gov (United States)

    El-Sherif, Ashraf F.; Gomaa, Walid; El-Sharkawy, Yasser H.

    2014-02-01

    The light interaction with tissue is governed by the specific wavelength of the laser used and the optical properties of target tissue. Absorption, scattering and fluorescence together can probably be used as the basis of quantitative diagnostic methods for teeth caries. The absorption coefficient of human teeth was determined from detached wet teeth (incisors and premolars). Laser absorption of these teeth was measured using compact blue laser source at wavelength of 457 nm and a high resolution spectrometer equipped with an integrating sphere. The average absorption coefficient of abnormal caries tissue of human teeth is observed to be higher than the normal ones. Detection and diagnosis of caries tissues were monitored by high resolution translational scanning of human teeth. We have a powerful tool to diagnosis a caries region of human teeth using blue laser at 457 nm. Ablations of caries region are investigated using higher power of blue laser at 457 nm.

  18. Photomechanical ablation of biological tissue induced by focused femtosecond laser and its application for acupuncture

    Science.gov (United States)

    Hosokawa, Yoichiroh; Ohta, Mika; Ito, Akihiko; Takaoka, Yutaka

    2013-03-01

    Photomechanical laser ablation due to focused femtosecond laser irradiation was induced on the hind legs of living mice, and its clinical influence on muscle cell proliferation was investigated via histological examination and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis to examine the expression of the gene encoding myostatin, which is a growth repressor in muscle satellite cells. The histological examination suggested that damage of the tissue due to the femtosecond laser irradiation was localized on epidermis and dermis and hardly induced in the muscle tissue below. On the other hand, gene expression of the myostatin of muscle tissue after laser irradiation was suppressed. The suppression of myostatin expression facilitates the proliferation of muscle cells, because myostatin is a growth repressor in muscle satellite cells. On the basis of these results, we recognize the potential of the femtosecond laser as a tool for noncontact, high-throughput acupuncture in the treatment of muscle disease.

  19. Keratin film ablation for the fabrication of brick and mortar skin structure using femtosecond laser pulses

    Science.gov (United States)

    Haq, Bibi Safia; Khan, Hidayat Ullah; Dou, Yuehua; Alam, Khan; Attaullah, Shehnaz; Zari, Islam

    2015-09-01

    The patterning of thin keratin films has been explored to manufacture model skin surfaces based on the "bricks and mortar" view of the relationship between keratin and lipids. It has been demonstrated that laser light is capable of preparing keratin-based "bricks and mortar" wall structure as in epidermis, the outermost layer of the human skin. "Bricks and mortar" pattern in keratin films has been fabricated using an ArF excimer laser (193 nm wavelength) and femtosecond laser (800 and 400 nm wavelength). Due to the very low ablation threshold of keratin, femtosecond laser systems are practical for laser processing of proteins. These model skin structures are fabricated for the first time that will help to produce potentially effective moisturizing products for the protection of skin from dryness, diseases and wrinkles.

  20. Structural characterization on in vitro porcine skin treated by ablative fractional laser using optical coherence tomography

    Science.gov (United States)

    Feng, Kairui; Zhou, Kanheng; Ling, Yuting; O'Mahoney, Paul; Ewan, Eadie; Ibbotson, Sally H.; Li, Chunhui; Huang, Zhihong

    2018-02-01

    Ablative fractional skin laser is widely applied for various skin conditions, especially for cosmetic repairing and promoting the located drug delivery. Although the influence of laser treatment over the skin has been explored before in means of excision and biopsy with microscopy, these approaches are invasive, only morphological and capable of distorting the skin. In this paper the authors use fresh porcine skin samples irradiated by the lasers, followed by detected by using Optical Coherence Tomography (OCT). This advanced optical technique has the ability to present the high resolution structure image of treated sample. The results shows that laser beams can produce holes left on the surface after the irradiation. The depth of holes can be affected by changes of laser energy while the diameter of holes have no corresponding relation. Plus, OCT, as a valuable imaging technology, is capable of monitoring the clinical therapy procedure and assisting the calibration.

  1. Improvement of the surface finish obtained by laser ablation with a Nd: YAG laser on pre-ablated tool steel

    CSIR Research Space (South Africa)

    Steyn, J

    2007-01-01

    Full Text Available Surface finish is an important requirement for tool and die makers and remains a challenge with conventional machining technologies. Nd: YAG lasers have been utilised for many years in the area of laser marking, engraving and micro machining...

  2. Aberration-sensing and wavefront-guided laser in situ keratomileusis: management of decentered ablation.

    Science.gov (United States)

    Mrochen, Michael; Krueger, Ronald R; Bueeler, Michael; Seiler, Theo

    2002-01-01

    To clarify the feasibility of aberration-sensing and wavefront-guided laser in situ keratomileusis (LASIK) to manage grossly decentered ablation and to discuss the limitations of the technology. Three patients with previous decentrations of the ablation zone between 1.5 to 2.0 mm were scheduled for wavefront-guided LASIK. All patients reported monocular diplopia and halos. Wavefront aberrations were measured with a Tscherning-type aberrometer. Laser ablation was done with a WaveLight Allegretto in a one-step procedure with ablation profiles calculated only from the individual wavefront map. Decentrations were determined from corneal topography. Three months after surgery, patient WM and patient SU had gained uncorrected and best spectacle-corrected visual acuity. The root mean square-wavefront error decreased up to 61% and 33%, respectively, for total and higher order aberrations (Zernike modes of 3rd order and higher). There was significant enlargement of the optical zone determined by corneal topography, and both patients no longer reported diplopia and halos at 3 months postoperatively. The optical aberration of the third patient (RE), after a 5.00-D overcorrection with a 2-mm decentration, was too high for aberration-sensing; retinal images obtained from the wavefront device were too smeared and not of sufficient contrast. In addition, this patient had a residual corneal thickness of 416 microm and thus wavefront-guided LASIK was not done. Wavefront-guided LASIK offers a new way of managing grossly decentered laser ablations. Unfortunately, there are still patients who have aberrations too large for wavefront sensing or with other clinical limitations such as a residual corneal thickness too thin for further treatment.

  3. Laser ablation deposition of superconducting Bi-Sr-Ca-Cu-O thin films on zirconia-buffered crystalline quartz

    International Nuclear Information System (INIS)

    Thin films of Bi-Sr-Ca-Cu-O have been deposited on crystalline quartz substrates by laser ablation. Without a buffer layer, superconducting regions exist in the films as detected by magnetically modulated microwave absorption. However, with a 1000-A zirconia buffer layer, also deposited by laser ablation, continuous, superconducting thin films were obtained. It is shown that both annealing temperature and annealing time greatly affect the film quality

  4. Tissue ablation and gas formation of two excimer laser systems: an in vitro evaluation on porcine aorta.

    Science.gov (United States)

    Appelman, Y E; Piek, J J; Verhoofstad, G G; Gijsbers, G H; Van Gemert, M J

    1996-01-01

    The relationship between tissue ablation volume and the formation of insoluble gas of the currently available excimer laser systems is unknown. This aspect was evaluated in two excimer laser systems. We measured tissue ablation volume and gas production of two excimer laser systems (308 nm) on porcine aortic tissue immersed in saline (the CVX-300 using 1.4 and 1.7 mm laser catheters and the Dymer 200 + using 1.3, 1.3z and 1.6 mm laser catheters). Tissue ablation volume and gas production increased proportionally with the applied energy fluence, ranging from 30-60 mJ/mm2. The gas production per unit of ablated tissue volume of the 1.4 mm laser catheter was significantly higher than the 1.3 mm laser catheter (mean difference +117%, 95% CI from +64% till +188%, PCVX-300 laser system results in significantly higher gas production than the Dymer 200+ laser system, which can be markedly reduced by lowering the applied energy fluence. The 1.3z laser catheter constitutes an exception, showing similar characteristics as the CVX-300 laser catheters.

  5. Stereotactic Laser Ablation for Medically Intractable Epilepsy: The Next Generation of Minimally Invasive Epilepsy Surgery

    Directory of Open Access Journals (Sweden)

    Michael Joseph LaRiviere

    2016-12-01

    Full Text Available Epilepsy is a common, disabling illness that is refractory to medical treatment in approximately one third of patients, particularly among those with mesial temporal lobe epilepsy. While standard open mesial temporal resection is effective, achieving seizure freedom in most patients, efforts to develop safer, minimally invasive techniques have been underway for over half a century. Stereotactic ablative techniques, in particular radiofrequency ablation, were first developed in the 1960s, with refinements in the 1990s with the advent of modern computed tomography and magnetic resonance-based imaging. In the past 5 years, the most recent techniques have used MRI-guided laser interstitial thermotherapy (LITT, whose development began in the 1980s, saw refinements in MRI thermal imaging through the 1990s, and was initially used primarily for the treatment of intracranial and extracranial tumors. The present review describes the original stereotactic ablation trials, followed by modern imaging-guided radiofrequency ablation series for mesial temporal lobe epilepsy. The development of LITT and MRI thermometry are then discussed. Finally, the two currently available MRI-guided laser interstitial thermotherapy systems are reviewed for their role in the treatment of mesial temporal lobe and other medically refractory epilepsies.

  6. Experiment and Prediction of Ablation Depth in Excimer Laser Micromachining of Optical Polymer Waveguides

    Directory of Open Access Journals (Sweden)

    K. F. Tamrin

    2018-01-01

    Full Text Available Extending the data transfer rates through dense interconnections at inter- and intraboard levels is a well-established technique especially in consumer electronics at the expense of more cross talk, electromagnetic interference (EMI, and power dissipation. Optical transmission using optical fibre is practically immune to the aforementioned factors. Among the manufacturing methods, UV laser ablation using an excimer laser has been repeatedly demonstrated as a suitable technique to fabricate multimode polymer waveguides. However, the main challenge is to precisely control and predict the topology of the waveguides without the need for extensive characterisation which is both time consuming and costly. In this paper, the authors present experimental results of investigation to relate the fluence, scanning speed, number of shots, and passes at varying pulse repetition rate with the depth of ablation of an acrylate-based photopolymer. The depth of ablation essentially affects total internal reflection and insertion loss, and these must be kept at minimum for a successful optical interconnection on printed circuit boards. The results are then used to predict depth of ablation for this material by means of adaptive neurofuzzy inference system (ANFIS modelling. The predicted results, with a correlation of 0.9993, show good agreement with the experimental values. This finding will be useful in better predictions along with resource optimisation and ultimately helps in reducing cost of polymer waveguide fabrication.

  7. Interferometric laser detection of nanomechanical perturbations in biological media under ablation conditions

    International Nuclear Information System (INIS)

    Morales-Bonilla, S; Torres-Torres, C; Urriolagoitia-Sosa, G; Hernandez-Gomez, L H; Urriolagoitia-Calderon, G

    2011-01-01

    This article has to do with the development of a reliable and sensitive non-invasive laser technique for assessing damage of structures and systems involved in laser ablation processes. The optical response of a Michelson Interferometer in combination with a Measuring Reflectance System has been analyzed in order to identify the stability of the mechanical properties of the sample, the physical perturbations associated with the systems and the environment where the target is contained. This test includes the use of a cyan laser system with 10 mW at 488 nm wavelength as optical source. We found out that with the inclusion of an optical feedback in a sensing system it is possible to determine the modification of the physical properties exhibited by a biological medium under sharp ablation conditions with a high accuracy degree. The results reported in this research have potential applications related to the amount of light intensity that can be tolerated by human tissue. A wide array of disciplines, such as medicine, mechanical industry and optical instrumentation can benefit from this ultrafast optical feedback for controlling high intensity laser signals. Collateral damage of tissue around the laser irradiated zones can be reduced by using intelligent lasers systems with ultra-short temporal response.

  8. Interferometric laser detection of nanomechanical perturbations in biological media under ablation conditions

    Science.gov (United States)

    Morales-Bonilla, S.; Torres-Torres, C.; Urriolagoitia-Sosa, G.; Hernández-Gómez, L. H.; Urriolagoitia-Calderón, G.

    2011-07-01

    This article has to do with the development of a reliable and sensitive non-invasive laser technique for assessing damage of structures and systems involved in laser ablation processes. The optical response of a Michelson Interferometer in combination with a Measuring Reflectance System has been analyzed in order to identify the stability of the mechanical properties of the sample, the physical perturbations associated with the systems and the environment where the target is contained. This test includes the use of a cyan laser system with 10 mW at 488 nm wavelength as optical source. We found out that with the inclusion of an optical feedback in a sensing system it is possible to determine the modification of the physical properties exhibited by a biological medium under sharp ablation conditions with a high accuracy degree. The results reported in this research have potential applications related to the amount of light intensity that can be tolerated by human tissue. A wide array of disciplines, such as medicine, mechanical industry and optical instrumentation can benefit from this ultrafast optical feedback for controlling high intensity laser signals. Collateral damage of tissue around the laser irradiated zones can be reduced by using intelligent lasers systems with ultra-short temporal response.

  9. Synthesis and characterization of PVK/AgNPs nanocomposites prepared by laser ablation

    Science.gov (United States)

    Abd El-kader, F. H.; Hakeem, N. A.; Elashmawi, I. S.; Menazea, A. A.

    2015-03-01

    Nanocomposites of Poly (n-vinylcarbazole) PVK/Ag nanoparticles were prepared by laser ablation of a silver plate in aqueous solution of chlorobenzene. The influences of laser parameters such as; time of irradiation, source power and wavelength (photon energy) on structural, morphological and optical properties have been investigated using X-ray diffraction (XRD), Transmission electron microscopy (TEM), Ultraviolet-visible (UV-Vis) and Photoluminescence (PL). A correlation between the investigated properties has been discussed. XRD, TEM and PL indicated that the complexation between AgNPs and PVK in the composite system is possible. Only the reflection peak at 2θ = 38° of AgNPs appeared in the composite nanoparticles while the other reflection peaks were destroyed. The nanoparticles shape and size distribution were evaluated from TEM images. TEM analysis revealed a lower average particle size at long laser irradiation time 40 min and short laser wavelength 532 nm together with high laser power 570 mW. From UV-Visible spectra the values of absorption coefficient, absorption edge and energy tail were calculated. The reduction of band tail value with increasing the laser ablation parameters confirms the decrease of the disorder in such composite system. The PL and UV-Vis. spectra confirm that nanocomposite samples showed quantum confinement effect.

  10. Laser-induced thermo ablation of hepatic tumors: an update review; Termoablacao a laser de tumores hepaticos: atualizacao

    Energy Technology Data Exchange (ETDEWEB)

    D' Ippolito, Giuseppe [Universidade Federal de Sao Paulo (UNIFESP/EPM), SP (Brazil). Dept. de Diagnostico por Imagem]. E-mail: scopo@terra.com.br; Ribeiro, Marcelo [Sao Paulo Univ., SP (Brazil). Hospital das Clinicas. Grupo de Cirurgia de Figado e Hipertensao Portal

    2004-06-01

    Laser-induced thermo ablation has been used as a reliable method for producing coagulation necrosis in hepatic tumors in patients who are not suitable for surgical treatment. The procedure can be performed percutaneously, using image-guiding methods, by open laparotomy or laparoscopy. We review the current literature and discuss the principles, indications, complications and clinical results as well as the potential limitations and contraindications of this novel technique. (author)

  11. Pulsed laser ablation of Germanium under vacuum and hydrogen environments at various fluences

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Muhammad Hassan [Centre for Advanced Studies in Physics, Government College University, Lahore (Pakistan); Bashir, Shazia, E-mail: shaziabashir@gcu.edu.pk [Centre for Advanced Studies in Physics, Government College University, Lahore (Pakistan); Rafique, Muhammad Shahid [Department of Physics, University of Engineering and Technology, Lahore (Pakistan); Dawood, Asadullah; Akram, Mahreen; Mahmood, Khaliq; Hayat, Asma; Ahmad, Riaz; Hussain, Tousif [Centre for Advanced Studies in Physics, Government College University, Lahore (Pakistan); Mahmood, Arshad [National Institute of Laser and Optronics (NILOP), Islamabad (Pakistan)

    2015-07-30

    Highlights: • Germanium targets were exposed under vacuum and H{sub 2} environment by nanosecond laser pulses. • The effect of laser fluence and ambient environment has been investigated. • The surface morphology is investigated by SEM analysis. • Raman and FTIR Spectroscopy are performed to reveal structural modification. • Electrical conductivity is probed by four probe method. - Abstract: Laser fluence and ambient environment play a significant role for the formation and development of the micro/nano-structures on the laser irradiated targets. Single crystal (1 0 0) Germanium (Ge) has been ablated under two environments of vacuum (10{sup −3} Torr) and hydrogen (100 Torr) at various fluences ranging from 4.5 J cm{sup −2} to 6 J cm{sup −2}. For this purpose KrF Excimer laser with wavelength of 248 nm, pulse duration of 18 ns and repetition rate of 20 Hz has been employed. Surface morphology has been observed by Scanning Electron Microscope (SEM). Whereas, structural modification of irradiated targets was explored by Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy. Electrical conductivity of the irradiated Ge is measured by four probe method. SEM analysis exhibits the formation of laser-induced periodic surface structures (LIPSS), cones and micro-bumps in both ambient environments (vacuum and hydrogen). The formation as well as development of these structures is strongly dependent upon the laser fluence and environmental conditions. The periodicity of LIPSS or ripples varies from 38 μm to 60 μm in case of vacuum whereas in case of hydrogen environment, the periodicity varies from 20 μm to 45 μm. The difference in number of ripples and periodicity as well as in shape and size of cones and bumps in vacuum and hydrogen is explained on the basis of confinement and shielding effect of plasma. FTIR spectroscopy reveals that no new bands are formed for laser ablated Ge under vacuum, whereas C−H stretching vibration band is

  12. Fabrication of multipoint side-firing optical fiber by laser micro-ablation.

    Science.gov (United States)

    Nguyen, Hoang; Parvez Arnob, Md Masud; Becker, Aaron T; Wolfe, John C; Hogan, Matthew K; Horner, Philip J; Shih, Wei-Chuan

    2017-05-01

    A multipoint, side-firing design enables an optical fiber to output light at multiple desired locations along the fiber body. This provides advantages over traditional end-to-end fibers, especially in applications requiring fiber bundles such as brain stimulation or remote sensing. This Letter demonstrates that continuous wave (CW) laser micro-ablation can controllably create conical-shaped cavities, or side windows, for outputting light. The dimensions of these cavities determine the amount of firing light and their firing angle. Experimental data show that a single side window on a 730 μm fiber can deliver more than 8% of the input light. This can be increased to more than 19% on a 65 μm fiber with side windows created using femtosecond laser ablation and chemical etching. Fine control of light distribution along an optical fiber is critical for various biomedical applications such as light-activated drug-release and optogenetics studies.

  13. Structural characterization of thin films of titanium nitride deposited by laser ablation

    International Nuclear Information System (INIS)

    Castro C, M.A.; Escobar A, L.; Camps C, E.; Mejia H, J.A.

    2004-01-01

    Thin films of titanium nitride were deposited using the technique of laser ablation. It was studied the effect of the density of laser energy used for ablation the target as well as of the pressure of the work gas about the structure and the hardness of the deposited thin films. Depending on the pressure of the work gas films was obtained with preferential orientation in the directions (200) and (111). At a pressure of 1 x 10 -2 Torr only the direction (200) was observed. On the other hand to the pressure of 5 x 10 -3 Torr the deposited material this formed by a mixture of the orientation (200) and (111), being the direction (111) the predominant one. Thin films of Ti N were obtained with hardness of up to 24.0 GPa that makes to these attractive materials for mechanical applications. The hardness showed an approximately linear dependence with the energy density. (Author)

  14. Expansion phenomena of aerosols generated by laser ablation under helium and argon atmosphere

    International Nuclear Information System (INIS)

    Koch, J.; Waelle, M.; Schlamp, S.; Roesgen, T.; Guenther, D.

    2008-01-01

    Specific expansion phenomena of aerosols generated by near infrared femtosecond laser ablation (NIR-fs-LA) of brass under helium and argon atmosphere were studied. For this purpose, particles were visualized by light scattering using a pulsed laser source. Aerosols were found to be captured in symmetric vortices when striking a solid boundary during their kinetic stage of expansion. Furthermore, high-repetitive LA resulted in the formation of a complex, macroscopic flow pattern driven by a pressure gradient locally built up. Our data indicate that aerosols released under those conditions experience only minor losses of around 1% if they get in contact with the inner walls of ablation cells operated at atmospheric pressures

  15. Influence of the atomic mass of the background gas on laser ablation plume propagation

    DEFF Research Database (Denmark)

    Amoruso, Salvatore; Schou, Jørgen; Lunney, James G.

    2008-01-01

    A combination of time-of-flight ion probe measurements and gas dynamical modeling has been used to investigate the propagation of a laser ablation plume in gases of different atomic/molecular weight. The pressure variation of the ion time-of-flight was found to be well described by the gas...... dynamical model of Predtechensky and Mayorov (Appl. Supercond. 1:2011, 1993). In particular, the model describes how the pressure required to stop the plume in a given distance depends on the atomic/molecular weight of the gas, which is a feature that cannot be explained by standard point......-blast-wave descriptions of laser ablation plume expansion in gas....

  16. Angular distribution of electron temperature and density in a laser-ablation plume

    DEFF Research Database (Denmark)

    Toftmann, B.; Schou, Jørgen; Hansen, T.N.

    2000-01-01

    The angular distribution of electron temperature and density in a laser-ablation plume has been studied for the first time. The electron temperature ranges from 0.1 to 0.5 eV and is only weakly dependent on the angle in the low-intensity range studied here. In contrast, the typical ion energy is ...... is about 2 orders of magnitude larger, and its angular distribution is mon peaked about the target normal. The derived Values of the electron density are in agreement with the measured values of ion density.......The angular distribution of electron temperature and density in a laser-ablation plume has been studied for the first time. The electron temperature ranges from 0.1 to 0.5 eV and is only weakly dependent on the angle in the low-intensity range studied here. In contrast, the typical ion energy...

  17. Infrared laser ablation and ionization of water clusters and biomolecules from ice

    International Nuclear Information System (INIS)

    Baltz-Knorr, M.L.; Schriver, K.E.; Haglund, R.F.

    2002-01-01

    We demonstrate the direct desorption and ionization of angiotensin II from frozen water ice samples without supplementary matrix, using a pulse train of approximately 340 intense (∼10 9 W/cm 2 ) picosecond pulses from a tunable, mid-infrared free-electron laser, at a wavelength of 5.9 μm. The pulse train was delivered at equally spaced intervals over a total duration of 120 ns. Ions thus formed were detected using a reflectron time-of-flight mass spectrometer. Single-shot ablation at spatially separated locations on the ice surface produced parent ions as well as Na and K adducts. Multiple pulse impact at a single location on the ice generated the parent ion signal and also protonated water clusters of the form (H 2 O) n-1 H 3 O + . Investigations of clusters produced by infrared laser ablation of frozen trifluoroacetic acid solution support a mechanism involving electrostatic ejection of pre-formed ions

  18. Analytical signal normalization in laser-enhanced ionization spectrometry with laser ablation of solid samples into a flame

    International Nuclear Information System (INIS)

    Labutin, T.A.; Popov, A.M.; Gorbatenko, A.A.; Zorov, N.B.

    2005-01-01

    The characteristics of analytical and reference signals (RS) were studied in laser-enhanced ionization (LEI) spectrometry combined with laser ablation of solid samples into a flame. Optoacoustic (OA) and atomic emission (AE) signals have been considered as possible RS. An algorithm of RS selection has been developed. Correlations between LEI signals and RS, which carry information on sample evaporation processes, have been explored. OA (the 1st minimum) and AE (AlI, λ = 396.1 nm) signals were found to be useful as RS (the correlation coefficients were 0.992 and 0.993, respectively). Both RS did not depend on the analyte (Li) content in the sample. It has been shown that the slope of the correlation plots (LEI vs. RS) depends on the Li content in the solid sample. This slope may be used as a novel type of normalized analytical signal, which does not depend on the ablation pulse energy. The influence of both ablating laser radiation characteristics and sample matrix composition on the analytical signal is eliminated (or at least diminished) when using this normalization

  19. Thin films of silver nanoparticles deposited in vacuum by pulsed laser ablation using a YAG:Nd laser

    International Nuclear Information System (INIS)

    Alonso, J.C.; Diamant, R.; Castillo, P.; Acosta-Garcia, M.C.; Batina, N.; Haro-Poniatowski, E.

    2009-01-01

    We report the deposition of thin films of silver (Ag) nanoparticles by pulsed laser ablation in vacuum using the third line (355 nm) of a YAG:Nd laser. The nanostructure and/or morphology of the films was investigated as a function of the number of ablation pulses, by means of transmission electron microscopy and atomic force microscopy. Our results show that films deposited with a small number of ablation pulses (500 or less), are not continuous, but formed of isolated nearly spherical Ag nanoparticles with diameters in the range from 1 nm to 8 nm. The effect of increasing the number of pulses by one order of magnitude (5000) is to increase the mean diameter of the globular nanoparticles and also the Ag areal density. Further increase of the number of pulses, up to 10,000, produces the formation of larger and anisotropic nanoparticles, and for 15,000 pulses, quasi-percolated Ag films are obtained. The presence of Ag nanoparticles in the films was also evidenced from the appearance of a strong optical absorption band associated with surface plasmon resonance. This band was widened and its peak shifted from 425 nm to 700 nm as the number of laser pulses was increased from 500 to 15,000.

  20. Selective laser etching or ablation for fabrication of devices

    KAUST Repository

    Buttner, Ulrich

    2017-01-12

    Methods of fabricating devices vial selective laser etching are provided. The methods can include selective laser etching of a portion of a metal layer, e.g. using a laser light source having a wavelength of 1,000 nm to 1,500 nm. The methods can be used to fabricate a variety of features, including an electrode, an interconnect, a channel, a reservoir, a contact hole, a trench, a pad, or a combination thereof. A variety of devices fabricated according to the methods are also provided. In some aspects, capacitive humidity sensors are provided that can be fabricated according to the provided methods. The capacitive humidity sensors can be fabricated with intricate electrodes, e.g. having a fractal pattern such as a Peano curve, a Hilbert curve, a Moore curve, or a combination thereof.

  1. Nonlinear spectrum of the ablative Rayleigh-Taylor instability in laser-accelerated planar plasmas

    International Nuclear Information System (INIS)

    Keskinen, M. J.; Schmitt, A.

    2007-01-01

    A model for the nonlinear spectrum of the ablative Rayleigh-Taylor instability in laser-accelerated planar plasmas has been developed for a wide range of Froude numbers and scale sizes. It is found that the spectrum can be characterized by an inverse power law with spectral index of approximately 2 in the limit of small-wavenumber spectrum cutoffs and small-scale density gradient scale lengths. Comparison of the model spectrum with recent experimental observations is made with good agreement

  2. IR Laser Ablative Decomposition of Poly(vinyl acetate) Loaded with Fe and Cu Particles

    Czech Academy of Sciences Publication Activity Database

    Blazevska-Gilev, J.; Kupčík, Jaroslav; Šubrt, Jan; Bastl, Zdeněk; Galíková, Anna; Pola, Josef

    2006-01-01

    Roč. 91, č. 9 (2006), s. 2241-2248 ISSN 0141-3910 R&D Projects: GA ČR(CZ) GA104/04/2028 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z40320502; CEZ:AV0Z40400503 Keywords : laser ablation * poly(vinyl acetate) * metal particles Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 2.174, year: 2006

  3. Low-Cost Facile Fabrication of Flexible Transparent Copper Electrodes by Nanosecond Laser Ablation

    KAUST Repository

    Paeng, Dongwoo

    2015-03-27

    © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Low-cost Cu flexible transparent conducting electrodes (FTCEs) are fabricated by facile nanosecond laser ablation. The fabricated Cu FTCEs show excellent opto-electrical properties (transmittance: 83%, sheet resistance: 17.48 Ω sq-1) with outstanding mechanical durability. Successful demonstration of a touch-screen panel confirms the potential applicability of Cu FTCEs to the flexible optoelectronic devices.

  4. US-Guided Femoral and Sciatic Nerve Blocks for Analgesia During Endovenous Laser Ablation

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, Saim, E-mail: ysaim@akdeniz.edu.tr; Ceken, Kagan; Alimoglu, Emel; Sindel, Timur [Akdeniz University School of Medicine, Department of Radiology (Turkey)

    2013-02-15

    Endovenous laser ablation may be associated with significant pain when performed under standard local tumescent anesthesia. The purpose of this study was to investigate the efficacy of femoral and sciatic nerve blocks for analgesia during endovenous ablation in patients with lower extremity venous insufficiency. During a 28-month period, ultrasound-guided femoral or sciatic nerve blocks were performed to provide analgesia during endovenous laser ablation in 506 legs and 307 patients. The femoral block (n = 402) was performed at the level of the inguinal ligament, and the sciatic block at the posterior midthigh (n = 124), by injecting a diluted lidocaine solution under ultrasound guidance. After the blocks, endovenous laser ablations and other treatments (phlebectomy or foam sclerotherapy) were performed in the standard fashion. After the procedures, a visual analogue pain scale (1-10) was used for pain assessment. After the blocks, pain scores were 0 or 1 (no pain) in 240 legs, 2 or 3 (uncomfortable) in 225 legs, and 4 or 5 (annoying) in 41 legs. Patients never experienced any pain higher than score 5. The statistical analysis revealed no significant difference between the pain scores of the right leg versus the left leg (p = 0.321) and between the pain scores after the femoral versus sciatic block (p = 0.7). Ultrasound-guided femoral and sciatic nerve blocks may provide considerable reduction of pain during endovenous laser and other treatments, such as ambulatory phlebectomy and foam sclerotherapy. They may make these procedures more comfortable for the patient and easier for the operator.

  5. IR Laser Ablation of Silicon Monoxide in Gaseous Methanol and Hydrocarbons: Deposition of Polyoxocarbosilane

    Czech Academy of Sciences Publication Activity Database

    Dřínek, Vladislav; Bastl, Zdeněk; Šubrt, Jan; Pola, Josef

    2004-01-01

    Roč. 71, č. 2 (2004), s. 431-444 ISSN 0165-2370 R&D Projects: GA ČR GA203/00/1288 Institutional research plan: CEZ:AV0Z4072921; CEZ:AV0Z4032918; CEZ:AV0Z4040901 Keywords : silicon monoxide * reactive laser ablation * polyoxocarbosilane coatings Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 1.352, year: 2004

  6. Linear and nonlinear characterization of surfaces from a laser beam melt ablation process

    Energy Technology Data Exchange (ETDEWEB)

    Bube, Kevin [Institut fuer Chemie und Biologie des Meeres, Carl-von-Ossietzky Universitaet Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany); Neto, Camilo Rodrigues [Institut fuer Chemie und Biologie des Meeres, Carl-von-Ossietzky Universitaet Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany); University of Sao Paulo, Av. Arlindo Bettio 1000, EACH, 03828-000 Sao Paulo (Brazil); Donner, Reik [Department of Physics, University of Potsdam, Am Neuen Palais 10, D-14469 Potsdam (Germany); Schwarz, Udo [Department of Physics, University of Potsdam, Am Neuen Palais 10, D-14469 Potsdam (Germany); Feudel, Ulrike [Institut fuer Chemie und Biologie des Meeres, Carl-von-Ossietzky Universitaet Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany)

    2006-04-07

    We apply linear and nonlinear methods to study the properties of surfaces generated by a laser beam melt ablation process. As a result we present a characterization and ordering of the surfaces depending on the adjusted process parameters. Our findings give some insight into the performance of two widely applied multifractal analysis methods-the detrended fluctuation analysis and the wavelet transform modulus maxima method-on short real world data.

  7. Laser-induced thermo ablation of hepatic tumors: an update review

    International Nuclear Information System (INIS)

    D'Ippolito, Giuseppe; Ribeiro, Marcelo

    2004-01-01

    Laser-induced thermo ablation has been used as a reliable method for producing coagulation necrosis in hepatic tumors in patients who are not suitable for surgical treatment. The procedure can be performed percutaneously, using image-guiding methods, by open laparotomy or laparoscopy. We review the current literature and discuss the principles, indications, complications and clinical results as well as the potential limitations and contraindications of this novel technique. (author)

  8. Advanced Coats’ disease treated with intravitreal bevacizumab combined with laser vascular ablation

    Directory of Open Access Journals (Sweden)

    Villegas VM

    2014-05-01

    Full Text Available Victor M Villegas,1 Aaron S Gold,1 Audina M Berrocal,2 Timothy G Murray11Ocular Oncology and Retina, Miami, FL, USA; 2Department of Ophthalmology, Bascom Palmer Eye Institute, Miller School of Medicine, University of Miami, Miami, FL, USAPurpose: To evaluate the impact of intravitreal bevacizumab combined with laser vascular ablation in the management of advanced Coats’ disease presenting with exudative retinal detachment.Methods: This was a retrospective review of 24 children that presented with exudative retinal detachments associated with advanced Coats’ disease. Mean patient age was 62 months (range 9–160 months. Presenting signs included retinal detachment in 24 children (100%, vascular telangiectasia in 24 children (100%, and retinal ischemia in 24 children (100%. Twenty of 24 children presented with elevated, vascular leakage in the fovea (83%. Two children presented with sub-retinal fibrosis associated with presumed long-standing retinal detachment without evidence of rhegmatogenous retinal detachment. Ten patients exhibited vascular alterations in the periphery of the second eye without clinical evidence of exudation. All 24 children were treated with a large-spot-size diode laser directly to areas of abnormal telangiectatic vasculature. All 24 children received intravitreal bevacizumab injection. Results: All 24 children had resolution of exudative retinal detachment, ablation of vascular telangiectasia, and anatomic improvement of the retina. No child exhibited progressive retinal detachment and no eye required enucleation. No cases of neovascular glaucoma were seen. Fellow eyes with peripheral vascular alterations showed no progression to exudative vasculopathy during the observation period. Intravitreal bevacizumab injection was not associated with endophthalmitis or systemically-observed complications.Conclusion: Repetitive intravitreal bevacizumab combined with laser vascular ablation may be utilized effectively

  9. US-Guided Femoral and Sciatic Nerve Blocks for Analgesia During Endovenous Laser Ablation

    International Nuclear Information System (INIS)

    Yilmaz, Saim; Ceken, Kagan; Alimoglu, Emel; Sindel, Timur

    2013-01-01

    Endovenous laser ablation may be associated with significant pain when performed under standard local tumescent anesthesia. The purpose of this study was to investigate the efficacy of femoral and sciatic nerve blocks for analgesia during endovenous ablation in patients with lower extremity venous insufficiency. During a 28-month period, ultrasound-guided femoral or sciatic nerve blocks were performed to provide analgesia during endovenous laser ablation in 506 legs and 307 patients. The femoral block (n = 402) was performed at the level of the inguinal ligament, and the sciatic block at the posterior midthigh (n = 124), by injecting a diluted lidocaine solution under ultrasound guidance. After the blocks, endovenous laser ablations and other treatments (phlebectomy or foam sclerotherapy) were performed in the standard fashion. After the procedures, a visual analogue pain scale (1–10) was used for pain assessment. After the blocks, pain scores were 0 or 1 (no pain) in 240 legs, 2 or 3 (uncomfortable) in 225 legs, and 4 or 5 (annoying) in 41 legs. Patients never experienced any pain higher than score 5. The statistical analysis revealed no significant difference between the pain scores of the right leg versus the left leg (p = 0.321) and between the pain scores after the femoral versus sciatic block (p = 0.7). Ultrasound-guided femoral and sciatic nerve blocks may provide considerable reduction of pain during endovenous laser and other treatments, such as ambulatory phlebectomy and foam sclerotherapy. They may make these procedures more comfortable for the patient and easier for the operator.

  10. Growth and structural properties of pulsed laser-ablated CuInSe2 nanoparticles by pulsed-laser ablation and selenization process

    International Nuclear Information System (INIS)

    Jeong, A.R.; Jo, W.; Ko, C.; Han, M.; Kang, S.J.; Kim, M.; Park, D.Y.; Cheong, H.; Yun, H.J.

    2011-01-01

    Highlights: → Pulsed laser ablated CuInSe 2 (CIS) nanoparticles show diverse structure for selenization. → Raman spectra show structural changes of CIS nanoparicles after selenization at different temperatures. → The A 1 mode 176 cm -1 indicates the chalcopyrite phase and coexistence with the CuAu-ordered phase. → Sphalerite structure with In 2 Se 3 is found at 182 cm -1 overlapped with the A 1 mode. → HR-TEM confirms the chalcopyrite structure in the nanoparticles. - Abstract: Nanoparticles of CuInSe 2 (CIS) were synthesized by pulsed laser ablation. The effect of the preparation conditions on the structural properties of the CIS nanoparticles was investigated. The CIS nanoparticles showed a more developed structural property after treatment in Se-evaporated atmosphere. By X-ray photoelectron spectroscopy, increase of Se amounts in the CIS nanoparticles was confirmed. Enhancement of phonon modes in the CIS nanoparticles was observed in Raman scattering spectroscopy while secondary phases like In 2 Se 3 or CuAu structure-related peak were identified in the spectra. High-resolution transmission electron microscopy indicated that the individual nanoparticles were embedded in matrix of some amorphous layers and diffraction patterns representing the chalcopyrite structure were also scrutinized.

  11. High Tc superconducting thin film deposition by excimer laser ablation

    International Nuclear Information System (INIS)

    Fogarassy, E.; Fuchs, C.; Stoquert, J.P.; Siffert, P.; Defourneau, R.M.; Perriere, J.; Rochet, F.; Rosenman, I.; Simon, C.

    1988-01-01

    The possibility to deposite YBaCuO and BiSrCaCuO thin films by laser evaporation in a clean environment has been studied using a pulsed ArF excimer laser. The as-deposited thin films were converted into the superconducting phase by a subsequent anneal in oxygen in the 850-900 0 C temperature range. The onset critical temperatures were respectively 85 and 92 K with a zero resistance at 83 K for BiSrCaCuO [fr

  12. Nanosecond pulsed laser ablation of brass in a dry and liquid-confined environment

    Science.gov (United States)

    Bashir, Shazia; Vaheed, Hamza; Mahmood, Khaliq

    2013-02-01

    The effect of ambient environment (dry or wet) and overlapping laser pulses on the laser ablation performance of brass has been investigated. For this purpose, a Q-switched, frequency doubled Nd:YAG laser with a wavelength of 532 nm, pulse energy of 150 mJ, pulse width of 6 ns and repetition rate of 10 Hz is employed. In order to explore the effect of ambient environments, brass targets have been exposed in deionized water, methanol and air. The targets are exposed for 1000, 2000, 3000 and 4000 succeeding pulses in each atmosphere. The surface morphology and chemical composition of ablated targets have been characterized by using Scanning Electron Microscope (SEM), Atomic Force Microscope (AFM) and Attenuated Total Reflection (ATR) techniques. In case of liquid environment, various features like nano- and micro-scale laser-induced periodic surface structures with periodicity 500 nm-1 μm, cavities of size few micrometers with multiple ablative layers and phenomenon of thermal stress cracking are observed. These features are originated by various chemical and thermal phenomena induced by laser heating at the liquid-solid interfaces. The convective bubble motion, explosive boiling, pressure gradients, cluster and colloid formation due to confinement effects of liquids are possible cause for such kind of features. The metal oxides and alcohol formed on irradiated surface are also playing the significant role for the formation of these kinds of structure. In case of air one huge crater is formed along with the redeposition of sputtered material and is ascribed to laser-induced evaporation and oxide formation.

  13. Preclinical investigations of articular cartilage ablation with femtosecond and pulsed infrared lasers as an alternative to microfracture surgery

    Science.gov (United States)

    Su, Erica; Sun, Hui; Juhasz, Tibor; Wong, Brian J. F.

    2014-01-01

    Abstract. Microfracture surgery is a bone marrow stimulation technique for treating cartilage defects and injuries in the knee. Current methods rely on surgical skill and instrumentation. This study investigates the potential use of laser technology as an alternate means to create the microfracture holes. Lasers investigated in this study include an erbium:YAG laser (λ=2.94  μm), titanium:sapphire femtosecond laser system (λ=1700  nm), and Nd:glass femtosecond laser (λ=1053  nm). Bovine samples were ablated at fluences of 8 to 18  J/cm2 with the erbium:YAG laser, at a power of 300±15  mW with the titanium:sapphire femtosecond system, and at an energy of 3  μJ/pulse with the Nd:glass laser. Samples were digitally photographed and histological sections were taken for analysis. The erbium:YAG laser is capable of fast and efficient ablation; specimen treated with fluences of 12 and 18  J/cm2 experienced significant amounts of bone removal and minimal carbonization with saline hydration. The femtosecond laser systems successfully removed cartilage but not clinically significant amounts of bone. Precise tissue removal was possible but not to substantial depths due to limitations of the systems. With additional studies and development, the use of femtosecond laser systems to ablate bone may be achieved at clinically valuable ablation rates. PMID:25200394

  14. Laser ablation of a silicon target in chloroform: formation of multilayer graphite nanostructures

    Science.gov (United States)

    Abderrafi, Kamal; García-Calzada, Raúl; Sanchez-Royo, Juan F.; Chirvony, Vladimir S.; Agouram, Saïd; Abargues, Rafael; Ibáñez, Rafael; Martínez-Pastor, Juan P.

    2013-04-01

    With the use of high-resolution transmission electron microscopy, selected area electron diffraction and x-ray photoelectron spectroscopy methods of analysis we show that the laser ablation of a Si target in chloroform (CHCl3) by nanosecond UV pulses (40 ns, 355 nm) results in the formation of about 50-80 nm core-shell nanoparticles with a polycrystalline core composed of small (5-10 nm) Si and SiC mono-crystallites, the core being coated by several layers of carbon with the structure of graphite (the shell). In addition, free carbon multilayer nanostructures (carbon nano-onions) are also found in the suspension. On the basis of a comparison with similar laser ablation experiments implemented in carbon tetrachloride (CCl4), where only bare (uncoated) Si nanoparticles are produced, we suggest that a chemical (solvent decomposition giving rise to highly reactive CH-containing radicals) rather than a physical (solvent atomization followed by carbon nanostructure formation) mechanism is responsible for the formation of graphitic shells. The silicon carbonization process found for the case of laser ablation in chloroform may be promising for silicon surface protection and functionalization.

  15. Quantitative images of metals in plant tissues measured by laser ablation inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Becker, J.S.; Dietrich, R.C.; Matusch, A.; Pozebon, D.; Dressler, V.L.

    2008-01-01

    Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used for quantitative imaging of toxic and essential elements in thin sections (thickness of 30 or 40 μm) of tobacco plant tissues. Two-dimensional images of Mg, Fe, Mn, Zn, Cu, Cd, Rh, Pt and Pb in leaves, shoots and roots of tobacco were produced. Sections of the plant tissues (fixed onto glass slides) were scanned by a focused beam of a Nd:YAG laser in a laser ablation chamber. The ablated material was transported with argon as carrier gas to the ICP ion source at a quadrupole ICP-MS instrument. Ion intensities of the investigated elements were measured together with 13 C + , 33 S + and 34 S + within the entire plant tissue section. Matrix matching standards (prepared using powder of dried tobacco leaves) were used to constitute calibration curves, whereas the regression coefficient of the attained calibration curves was typically 0.99. The variability of LA-ICP-MS process, sample heterogeneity and water content in the sample were corrected by using 13 C + as internal standard. Quantitative imaging of the selected elements revealed their inhomogeneous distribution in leaves, shoots and roots

  16. Capabilities of laser ablation mass spectrometry in the differentiation of natural and artificial opal gemstones.

    Science.gov (United States)

    Erel, Eric; Aubriet, Frédéric; Finqueneisel, Gisèle; Muller, Jean-François

    2003-12-01

    The potentialities of laser ablation coupled to ion cyclotron resonance Fourier transform mass spectrometry are evaluated to distinguish natural and artificial opals. The detection of specific species in both ion detection modes leads us to obtain relevant criteria of differentiation. In positive ions, species including hafnium and large amounts of zirconium atoms are found to be specific for artificial opal. In contrast, aluminum, titanium, iron, and rubidium are systematically detected in the study of natural opals. Moreover, some ions allow us to distinguish between natural opal from Australia and from Mexico. Australian gemstone includes specifically strontium, cesium, and barium. Moreover, it is also found that the yield of (H2O)0-1(SiO2)nX- (X- = O-, OH-, KO-, NaO-, SiO2-, AlO1-2-, FeO2-, ZrO2-, and ZrO3-) and (Al2O3)(SiO2)nAlO2- ions depends on the composition of the sample when opals are laser ablated. Ions, which include zirconium oxide species, are characteristics of artificial gem. In contrast, natural opals lead us, after laser ablation, to the production of ions including H2O, Al2O3 motifs and AlO-, KO-, NaO-, and FeO2- species.

  17. One-step fabrication of superhydrophobic hierarchical structures by femtosecond laser ablation

    International Nuclear Information System (INIS)

    Rukosuyev, Maxym V.; Lee, Jason; Cho, Seong Jin; Lim, Geunbae; Jun, Martin B.G.

    2014-01-01

    Highlights: • Superhydrophobic surface patterns by femtosecond laser ablation in open air. • Micron scale ridge-like structure with superimposed submicron convex features. • Hydrophobic or even superhydrophobic behavior with no additional silanization. - Abstract: Hydrophobic surface properties are sought after in many areas of research, engineering, and consumer product development. Traditionally, hydrophobic surfaces are produced by using various types of coatings. However, introduction of foreign material onto the surface is often undesirable as it changes surface chemistry and cannot provide a long lasting solution (i.e. reapplication is needed). Therefore, surface modification by transforming the base material itself can be preferable in many applications. Femtosecond laser ablation is one of the methods that can be used to create structures on the surface that will exhibit hydrophobic behavior. The goal of the presented research was to create micro and nano-scale patterns that will exhibit hydrophobic properties with no additional post treatment. As a result, dual scale patterned structures were created on the surface of steel aluminum and tungsten carbide samples. Ablation was performed in the open air with no subsequent treatment. Resultant surfaces appeared to be strongly hydrophobic or even superhydrophobic with contact angle values of 140° and higher. In conclusion, the nature of surface hydrophobicity proved to be highly dependent on surface morphology as the base materials used are intrinsically hydrophilic. It was also proven that the hydrophobicity inducing structures could be manufactured using femtosecond laser machining in a single step with no subsequent post treatment

  18. Endovenous laser ablation is an effective treatment for great saphenous vein incompetence in teenagers.

    Science.gov (United States)

    Terlecki, Piotr; Przywara, Stanislaw; Iłżecki, Marek; Terlecki, Karol; Kawecki, Piotr; Zubilewicz, Tomasz

    2016-04-01

    The current knowledge of chronic venous disease in teenagers and its treatment is very limited. The aim of the study is to present our experience and the available literature data on the treatment of varicose veins in teenagers with endovenous laser ablation of the great saphenous vein. Five patients, aged 15-17 years, were qualified for surgery, based on typical signs and symptoms of chronic venous disease. Minimally invasive treatment with endovenous laser ablation of the great saphenous vein was applied. The technical success of surgery was achieved in all patients. Over a 2-year follow-up we did not observe any case of recanalisation of the great saphenous vein, recurrence of varicose veins, or serious complications, such as deep vein thrombosis or pulmonary embolism. One patient presented with resolving of post-operative bruising, and two cases of local numbness were transient. Endovenous laser ablation of the great saphenous vein in the treatment of chronic venous disease in teenagers is effective and safe. The method provides excellent cosmetic effects, very short recovery time and high levels of patient satisfaction. © The Author(s) 2015.

  19. Green synthesis of selenium nanoparticles by excimer pulsed laser ablation in water

    Directory of Open Access Journals (Sweden)

    O. Van Overschelde

    2013-10-01

    Full Text Available Pure selenium nanoparticles were successfully synthesized by Liquid Phase - Pulsed Laser Ablation (LP-PLA in de-ionized water. Excimer laser (248 nm operating at low fluence (F ∼ 1 J/cm2 was used to generate colloidal solutions of selenium nanoparticles. The obtained selenium nanoparticles were characterized by UV-visible spectroscopy, Raman spectroscopy, Dynamic Light Scattering, and Transmission Electron Microscopy. We describe the multi-modal size distributions generated and use the centrifugation method to isolate the smallest nanoparticles (∼60 nm in diameter.

  20. Analysis of arsenic and calcium in soil samples by laser ablation mass spectrometry

    International Nuclear Information System (INIS)

    Beccaglia, Ana M.; Rinaldi, Carlos A.; Ferrero, Juan C.

    2006-01-01

    We present an analytical procedure based on laser ablation mass spectrometry (LAMS) in order to detect and quantify arsenic and calcium in soil samples and we analyze the diverse factors that influence the precision of LAMS, such as laser fluence and matrix effect. The results indicate that a Zn matrix is a good choice for the analysis of those metals in soil samples. This work also provides a method for the direct determination of As in soil samples whose concentrations are lower than 100 ppm with a 70 ppm minimum detection limits (MDL)

  1. Preparation of silver nanoparticles in virgin coconut oil using laser ablation

    OpenAIRE

    Zamiri, Reza; Azmi, B Z; Sadrolhosseini, Amir Reza; Ahangar, Hossein Abbastabar; Zaidan, A W; Mahdi, M A

    2011-01-01

    Reza Zamiri1, B Z Azmi1,2, Amir Reza Sadrolhosseini1, Hossein Abbastabar Ahangar3, A W Zaidan1, M A Mahdi41Department of Physics, 2Advanced Materials and Nanotechnology Laboratory, 3Department of Chemistry, 4Wireless and Photonics Networks Research Center, Universiti Putra Malaysia, Serdang, Selangor, MalaysiaAbstract: Laser ablation of a silver plate immersed in virgin coconut oil was carried out for fabrication of silver nanoparticles. A Nd:YAG laser at wavelengths of 1064 nm was used for a...

  2. Reduction of secondary electron yield for E-cloud mitigation by laser ablation surface engineering

    Energy Technology Data Exchange (ETDEWEB)

    Valizadeh, R., E-mail: reza.valizadeh@stfc.ac.uk [ASTeC, STFC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Malyshev, O.B. [ASTeC, STFC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Wang, S. [ASTeC, STFC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Department of Physics, Loughborough University, Loughborough LE11 3TU (United Kingdom); Sian, T. [ASTeC, STFC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); The Photon Science Institute, The University of Manchester, Manchester M13 9PL (United Kingdom); Cropper, M.D. [Department of Physics, Loughborough University, Loughborough LE11 3TU (United Kingdom); Sykes, N. [Micronanics Ltd., Didcot, Oxon OX11 0QX (United Kingdom)

    2017-05-15

    Highlights: • SEY below 1 can be achieved with Laser ablation surface engineering. • SEY <1 surface can be produced with different types of nanosecond lasers. • Both microstructure (groves) and nano-structures are playing a role in reducing SEY. - Abstract: Developing a surface with low Secondary Electron Yield (SEY) is one of the main ways of mitigating electron cloud and beam-induced electron multipacting in high-energy charged particle accelerators. In our previous publications, a low SEY < 0.9 for as-received metal surfaces modified by a nanosecond pulsed laser was reported. In this paper, the SEY of laser-treated blackened copper has been investigated as a function of different laser irradiation parameters. We explore and study the influence of micro- and nano-structures induced by laser surface treatment in air of copper samples as a function of various laser irradiation parameters such as peak power, laser wavelength (λ = 355 nm and 1064 nm), number of pulses per point (scan speed and repetition rate) and fluence, on the SEY. The surface chemical composition was determined by x-ray photoelectron spectroscopy (XPS) which revealed that heating resulted in diffusion of oxygen into the bulk and induced the transformation of CuO to sub-stoichiometric oxide. The surface topography was examined with high resolution scanning electron microscopy (HRSEM) which showed that the laser-treated surfaces are dominated by microstructure grooves and nanostructure features.

  3. Investigation of Ag nanoparticles produced by nanosecond pulsed laser ablation in water

    Energy Technology Data Exchange (ETDEWEB)

    Nikolov, A.S.; Nedyalkov, N.N.; Nikov, R.G.; Atanasov, P.A. [Bulgarian Academy of Sciences, Institute of Electronics, Sofia (Bulgaria); Alexandrov, M.T. [Bulgarian Academy of Sciences, Institute of Experimental Pathology and Parasitology, Sofia (Bulgaria); Karashanova, D.B. [Bulgarian Academy of Sciences, Institute of Optical Materials and Technologies, Sofia (Bulgaria)

    2012-11-15

    A study is presented of the properties of Ag nanoparticles produced by nanosecond pulsed laser ablation in twice-distilled water. An Ag target was immersed in the liquid and irradiated by the fundamental, second, third and fourth harmonics of a Nd:YAG laser system to create different colloids. Two specific boundary values of the laser fluence were applied for each wavelength. The properties of the nanoparticles at different wavelengths of the laser radiation were examined. The characterization of the colloids was performed immediately after their fabrication. Spherical and spherical-like shapes of the nanoparticles created were established. The formation of nanowires was observed when the second and the third harmonics of the laser were used. It is connected with self-absorption of the incident laser light from the already-created nanoparticles and depends also on the laser fluence. The size distribution of the nanoparticles is estimated by transmission electron microscopy. Generally, their mean size and standard deviation decreased as the wavelength of the incident laser light was increased and increased with the increase of the laser fluence. The substantial discrepancy between the results already commented on for both characteristics considered and others, obtained by dynamic light scattering, is discussed. The structure of the nanoparticles was established to be single and polycrystalline, and the phase composition in both cases is identified as consisting of cubic silver. The nanoparticles are slightly oxidized. (orig.)

  4. Time-resolved analysis of thickness-dependent dewetting and ablation of silver films upon nanosecond laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Dongfeng [Laser Thermal Laboratory, Department of Mechanical Engineering, University of California, Berkeley, California 94720-1740 (United States); Semiconductor Photonics Research Center, Department of Physics, Xiamen University, Xiamen 361005 (China); Paeng, Dongwoo; Yeo, Junyeob; Kim, Eunpa; Wang, Letian; Grigoropoulos, Costas P., E-mail: cgrigoro@berkeley.edu [Laser Thermal Laboratory, Department of Mechanical Engineering, University of California, Berkeley, California 94720-1740 (United States); Chen, Songyan [Semiconductor Photonics Research Center, Department of Physics, Xiamen University, Xiamen 361005 (China)

    2016-05-23

    Nanosecond pulsed laser dewetting and ablation of thin silver films is investigated by time-resolved imaging. Laser pulses of 532 nm wavelength and 5 ns temporal width are irradiated on silver films of different thicknesses (50 nm, 80 nm, and 350 nm). Below the ablation threshold, it is observed that the dewetting process does not conclude until 630 ns after the laser irradiation for all samples, forming droplet-like particles in the spot central region. At higher laser intensities, ablative material removal occurs in the spot center. Cylindrical rims are formed in the peripheral dewetting zone due to the solidification of transported matter at about 700 ns following the laser pulse exposure. In addition to these features, droplet fingers are superposed upon irradiation of 350-nm thick silver films with higher intensity.

  5. Diode-laser ablation therapy for submucosal gastric cancer using indocyanine-green solution injection to the submucosa

    Science.gov (United States)

    Hayashi, Takuya; Arai, Tsunenori; Tokonabe, Shigeki; Itoh, Harumi; Kikuchi, Makoto; Hino, Shoryoku; Masuda, Katsunori; Suzuki, Hiroaki; Tajiri, Hisao; Hino, Kunihiko; Nogami, Yashiroh

    1997-06-01

    A 805-nm diode laser ablation therapy with indocyanine green (ICG) was studied for the endoscopic treatment of early gastric cancer. The ICG solution with 1mg/ml was administrated to the submucosa of the resected porcine and anesthetized canine stomach for the purpose of enhancing the tissue absorption to the laser light. We established complete removal of the mucosa and the submucosa with laser power of 12 or 25 watts. The proper muscle was intact because the ICG solution prevents the laser light penetration to the proper muscle. An ablated depth could be easily recognized by observing the ablated surface color. Our results showed that the combination of the 805 nm diode laser irradiation and the submucosal injection of the ICG solution might provide selective and controllable endoscopic treatment for early gastric cancer.

  6. Femtosecond pulsed laser ablation to enhance drug delivery across the skin.

    Science.gov (United States)

    Garvie-Cook, Hazel; Stone, James M; Yu, Fei; Guy, Richard H; Gordeev, Sergey N

    2016-01-01

    Laser poration of the skin locally removes its outermost, barrier layer, and thereby provides a route for the diffusion of topically applied drugs. Ideally, no thermal damage would surround the pores created in the skin, as tissue coagulation would be expected to limit drug diffusion. Here, a femtosecond pulsed fiber laser is used to porate mammalian skin ex vivo. This first application of a hollow core negative curvature fiber (HC-NCF) to convey a femtosecond pulsed, visible laser beam results in reproducible skin poration. The effect of applying ink to the skin surface, prior to ultra-short pulsed ablation, has been examined and Raman spectroscopy reveals that the least, collateral thermal damage occurs in inked skin. Pre-application of ink reduces the laser power threshold for poration, an effect attributed to the initiation of plasma formation by thermionic electron emission from the dye in the ink. Poration under these conditions significantly increases the percutaneous permeation of caffeine in vitro. Dye-enhanced, plasma-mediated ablation of the skin is therefore a potentially advantageous approach to enhance topical/transdermal drug absorption. The combination of a fiber laser and a HC-NCF, capable of emitting and delivering femtosecond pulsed, visible light, may permit a compact poration device to be developed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. High contrast optical imaging methods for image guided laser ablation of dental caries lesions

    Science.gov (United States)

    LaMantia, Nicole R.; Tom, Henry; Chan, Kenneth H.; Simon, Jacob C.; Darling, Cynthia L.; Fried, Daniel

    2014-02-01

    Laser based methods are well suited for automation and can be used to selectively remove dental caries to minimize the loss of healthy tissues and render the underlying enamel more resistant to acid dissolution. The purpose of this study was to determine which imaging methods are best suited for image-guided ablation of natural non-cavitated carious lesions on occlusal surfaces. Multiple caries imaging methods were compared including near-IR and visible reflectance and quantitative light fluorescence (QLF). In order for image-guided laser ablation to be feasible, chemical and physical modification of tooth surfaces due to laser irradiation cannot greatly reduce the contrast between sound and demineralized dental hard tissues. Sound and demineralized surfaces of 48 extracted human molar teeth with non-cavitated lesions were examined. Images were acquired before and after laser irradiation using visible and near-IR reflectance and QLF at several wavelengths. Polarization sensitive-optical coherence tomography was used to confirm that lesions were present. The highest contrast was attained at 1460-nm and 1500-1700-nm, wavelengths coincident with higher water absorption. The reflectance did not decrease significantly after laser irradiation for those wavelengths.

  8. Optical properties of Germanium nanoparticles synthesized by pulsed laser ablation in acetone

    Directory of Open Access Journals (Sweden)

    Saikiran eVadavalli

    2014-10-01

    Full Text Available Germanium (Ge nanoparticles (NPs are synthesized by means of pulsed laser ablation of bulk germanium target immersed in acetone with ns laser pulses at different pulse energies. The fabricated NPs are characterized by employing different techniques such as UV-visible absorption spectroscopy, photoluminescence, micro-Raman spectroscopy, transmission electron microscopy (TEM and field emission scanning electron microscopy (FESEM. The mean size of the Ge NPs is found to vary from few nm to 40 nm with the increase in laser pulse energy. Shift in the position of the absorption spectra is observed and also the photoluminescence peak shift is observed due to quantum confinement effects. High resolution TEM combined with micro-Raman spectroscopy confirms the crystalline nature of the generated germanium nanoparticles. The formation of various sizes of germanium NPs at different laser pulse energies is evident from the asymmetry in the Raman spectra and the shift in its peak position towards the lower wavenumber side. The FESEM micrographs confirm the formation of germanium micro/nanostructures at the laser ablated position of the bulk germanium. In particular, the measured NP sizes from the micro-Raman phonon quantum confinement model are found in good agreement with TEM measurements of Ge NPs.

  9. Minimizing matrix effect by femtosecond laser ablation and ionization in elemental determination.

    Science.gov (United States)

    Zhang, Bochao; He, Miaohong; Hang, Wei; Huang, Benli

    2013-05-07

    Matrix effect is unavoidable in direct solid analysis, which usually is a leading cause of the nonstoichiometric effect in quantitative analysis. In this research, experiments were carried out to study the overall characteristics of atomization and ionization in laser-solid interaction. Both nanosecond (ns) and femtosecond (fs) lasers were applied in a buffer-gas-assisted ionization source coupled with an orthogonal time-of-flight mass spectrometer. Twenty-nine solid standards of ten different matrices, including six metals and four dielectrics, were analyzed. The results indicate that the fs-laser mode offers more stable relative sensitivity coefficients (RSCs) with irradiance higher than 7 × 10(13) W·cm(-2), which could be more reliable in the determination of element composition of solids. The matrix effect is reduced by half when the fs-laser is employed, owing to the fact that the fs-laser ablation and ionization (fs-LAI) incurs an almost heat-free ablation process and creates a dense plasma for the stable ionization.

  10. Synthesis of bimetallic nanostructures by nanosecond laser ablation of multicomponent thin films in water

    Science.gov (United States)

    Nikov, R. G.; Nedyalkov, N. N.; Atanasov, P. A.; Karashanova, D. B.

    2018-03-01

    The paper presents results on nanosecond laser ablation of thin films immersed in a liquid. The thin films were prepared by consecutive deposition of layers of different metals by thermal evaporation (first layer) and classical on-axis pulsed laser deposition (second layer); Ni/Au, Ag/Au and Ni/Ag thin films were thus deposited on glass substrates. The as-prepared films were then placed at the bottom of a glass vessel filled with double distilled water and irradiated by nanosecond laser pulses delivered by a Nd:YAG laser system at λ = 355 nm. This resulted in the formation of colloids of the thin films’ material. We also compared the processes of ablation of a bulk target and a thin film in the liquid by irradiating a Au target and a Au thin film by the same laser wavelength and fluence (λ = 355 nm, F = 5 J/cm2). The optical properties of the colloids were evaluated by optical transmittance measurements in the UV– VIS spectral range. Transmission electron microscopy was employed to estimate the particles’ size distribution.

  11. Selective ablation of dental enamel and dentin using femtosecond laser pulses

    International Nuclear Information System (INIS)

    Lizarelli, R F Z; Costa, M M; Carvalho-Filho, E; Bagnato, V S; Nunes, F D

    2008-01-01

    The study of the interaction of intense laser light with matter, as well as transient response of atoms and molecules is very appropriated because of the laser energy concentration in a femtosecond optical pulses. The fundamental problem to be solved is to find tools and techniques which allow us to observe and manipulate on a femtosecond time scale the photonics events on and into the matter. Six third human extracted molars were exposed to a femtosecond Ti:Sapphire Q-switched and mode locked laser (Libra-S, Coherent, Palo Alto, CA, USA), emitting pulses with 70 fs width, radiation wavelength of 801 nm, at a constant pulse repetition rate of 1 KHz. The laser was operated at different power levels (70 to 400 mW) with constant exposition time of 10 seconds, at focused and defocused mode. Enamel and dentin surfaces were evaluated concerned ablation rate and morphological aspects under scanning electron microscopic. The results in this present experiment suggest that at the focused mode and under higher average power, enamel tissues present microcavities with higher depth and very precise edges, but, while dentin shows a larger melt-flushing, lower depth and melting and solidification aspect. In conclusion, it is possible to choose hard or soft ablation, under lower and higher average power, respectively, revealing different aspects of dental enamel and dentin, depending on the average power, fluence and distance from the focal point of the ultra-short pulse laser on the tooth surface

  12. Initiation of an early-stage plasma during picosecond laser ablation of solids

    International Nuclear Information System (INIS)

    Mao, Samuel S.; Mao, Xianglei; Greif, Ralph; Russo, Richard E.

    2000-01-01

    Picosecond time-resolved images of plasma initiation were recorded during pulsed-laser ablation of metal targets in an air atmosphere. An early-stage plasma was observed to form before the release of a material vapor plume. Close to the target surface, interferometry measurements indicate that the early-stage plasma has an electron number density on the order of 10 20 cm -3 . The longitudinal expansion of the ionization front for this plasma has a velocity 10 9 cm/s, during the laser pulse. In contrast, a material--vapor plume forms approximately 200 ps after the laser pulse, and it moves away from the target at 10 6 cm/s. The experimental observations of the early-stage plasma were simulated by using a theoretical model based on a two-fluids description of laser plasmas. The results indicate that the initiation of the plasma is due to air breakdown assisted by electron emission from the target

  13. KrF laser ablation of a polyethersulfone film: Effect of pulse duration on structure formation

    International Nuclear Information System (INIS)

    Pazokian, Hedieh; Selimis, Alexandros; Stratakis, Emmanuel; Mollabashi, Mahmoud; Barzin, Jalal; Jelvani, Saeid

    2011-01-01

    Polyethersulfone (PES) films were processed with KrF laser irradiation of different pulse durations (τ). Scanning electron microscopy (SEM) and Raman spectroscopy were employed for the examination of the morphology and chemical composition of the irradiated surfaces, respectively. During ablation with 500 fs and 5 ps pulses, localized deformations (beads), micro-ripple and conical structures were observed on the surface depending on the irradiation fluence (F) and the number of pulses (N). In addition, the number density of the structures is affected by the irradiation parameters (τ, F, N). Furthermore, at longer pulse durations (τ = 30 ns), conical structures appear at lower laser fluence values, which are converted into columnar structures upon irradiation at higher fluences. The Raman spectra collected from the top of the structures following irradiation at different pulse durations revealed graphitization of the ns laser treated areas, in contrast to those processed with ultra-short laser pulses.

  14. Lichen amyloidosis successfully treated with fractional ablative laser CO2: A new alternative therapeutic.

    Science.gov (United States)

    Korbi, Mouna; Akkari, Hayet; Soua, Yosra; Mohamed, Mariem; Youssef, Monia; Belhajdali, Hichem; Zili, Jameledine

    2018-02-05

    Lichen amyloidosis is a primary localized cutaneous amyloidosis. Different types of treatment have been used without complete resolution. Herein, we report a case of patient suffering from lichen amyloidosis successfully treated with fractional ablative laser CO 2 . He was a 59-year-old man diagnosed lichen amyloidosis localized on the legs 10 years ago. He was treated with topical corticosteroids without any improvement. Then, we started treating the affected area with CO 2 laser (limmer*) at a setting of 5-8 J/cm 2 and 8 mm laser spot size. A considerable improvement was noticed after the first session. A total healing was reported after four sessions. To the best of our knowledge, only 11 reported cases of lichen amyloidosis have been successfully treated with laser CO 2 . However, our clinical finding seems to be one of the best reported results.

  15. Influence of consecutive picosecond pulses at 532 nm wavelength on laser ablation of human teeth

    Science.gov (United States)

    Mirdan, Balsam M.; Antonelli, Luca; Batani, Dimitri; Jafer, Rashida; Jakubowska, Katarzyna; Tarazi, Saad al; Villa, Anna Maria; Vodopivec, Bruno; Volpe, Luca

    2014-07-01

    The interaction of 40 ps pulse duration laser emitting at 532 nm wavelength with human dental tissue (enamel, dentin, and dentin-enamel junction) has been investigated. The crater profile and the surface morphology have been studied by using a confocal auto-fluorescence microscope (working in reflection mode) and a scanning electron microscope. Crater profile and crater morphology were studied after applying consecutive laser pulses and it was found that the ablation depth increases with the number of consecutive pulses, leaving the crater diameter unchanged. We found that the thermal damage is reduced by using short duration laser pulses, which implies an increased retention of restorative material. We observe carbonization of the irradiated samples, which does not imply changes in the chemical composition. Finally, the use of 40 ps pulse duration laser may become a state of art in conservative dentistry.

  16. Microchannel fabrication on cyclic olefin polymer substrates via 1064 nm Nd:YAG laser ablation

    International Nuclear Information System (INIS)

    McCann, Ronán; Bagga, Komal; Groarke, Robert; Stalcup, Apryll; Vázquez, Mercedes; Brabazon, Dermot

    2016-01-01

    Highlights: • Rapid single-step microchannel fabrication on optically transparent cyclic olefin polymer using IR Nd:YAG laser. • Ability to tailor channel depth between 12–47 μm demonstrated for single laser pass. • Use of multiple laser passes showed capability for finer depth control. • Potential applications in lab-on-chip and microfluidic devices. - Abstract: This paper presents a method for fabrication of microchannels on cyclic olefin polymer films that have application in the field of microfluidics and chemical sensing. Continuous microchannels were fabricated on 188-μm-thick cyclic olefin polymer substrates using a picosecond pulsed 1064 nm Nd:YAG laser. The effect of laser fluence on the microchannel morphology and dimensions was analysed via scanning electron microscopy and optical profilometry. Single laser passes were found to produce v-shaped microchannels with depths ranging from 12 μm to 47 μm and widths from 44 μm to 154 μm. The ablation rate during processing was lower than predicted theoretically. Multiple laser passes were applied to examine the ability for finer control over microchannel morphology with channel depths ranging from 22 μm to 77 μm and channel widths from 59 μm to 155 μm. For up to five repeat passes, acceptable reproducibility was found in the produced microchannel morphology. Infrared spectroscopy revealed oxidation and dehydrogenation of the polymer surface following laser ablation. These results were compared to other work conducted on cyclic olefin polymers.

  17. Laser Ablation Characterization in Laboratori Nazionali di Legnaro

    Science.gov (United States)

    Scarpa, D.; Nicolosi, P.; Franci, A.; Tomaselli, A.; Manzolaro, M.; Corradetti, S.; Vasquez, J.; Rossignoli, M.; Calderolla, M.; Monetti, A.; Andrighetto, A.; Prete, G.

    2014-04-01

    Using high power laser focalized into a target material generates plasma and it has the consequence to immediately extract and ionize atoms from the target itself. This process is the starting point to have a simple and compact ion source, usually named Laser Ion Source (LIS). This kind of sources are arising in the scenario of ion sources especially in refractory elements ions production, where the atomization of the material to ionize is the main issue because of its high evaporating temperature. These considerations and the fact that ion sources are becoming nowadays more and more important to several fields of science and technology, open an interesting line of research that our group at Laboratori Nazionali di Legnaro wants to investigate. Experiment involves characterization of produced ions by measuring charge state and amount of ions created. Measurements will be performed with several power densities and varying ions collector distance and potential respect to the target. These simple experiments are the necessary preliminary steps to characterize the system and to start a solid future development onto possible different and effective ways to perform ions sources using laser.

  18. Dynamics of colliding aluminium plasmas produced by laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Gambino, N., E-mail: gambino@lec.mavt.ethz.ch [INFN-Laboratori Nazionali del Sud, Via S.Sofia, 62, I95123 Catania (Italy); IET-Institute of Energy Technology, LEC-Laboratory for Energy Conversion, ETH Zurich, Sonneggstrasse 3, CH-8092 Zurich (Switzerland); Hayden, P. [School of Physical Sciences and National Centre for Plasma Science and Technology, Dublin City University, Glasnevin, Dublin 9 (Ireland); Mascali, D. [INFN-Laboratori Nazionali del Sud, Via S.Sofia, 62, I95123 Catania (Italy); Costello, J.; Fallon, C.; Hough, P.; Yeates, P. [School of Physical Sciences and National Centre for Plasma Science and Technology, Dublin City University, Glasnevin, Dublin 9 (Ireland); Anzalone, A.; Musumeci, F.; Tudisco, S. [INFN-Laboratori Nazionali del Sud, Via S.Sofia, 62, I95123 Catania (Italy)

    2013-05-01

    The collision of two aluminium plasmas was investigated by combining both time and space resolved spectroscopy and Langmuir probe measurements. Plasma plumes were produced by a Continuum™ Surelite Nd:YAG Laser System with pulse duration of FWHM of 6 ns and wavelength of 1064 nm, at a laser irradiance of 10{sup 11} W/cm{sup 2} on slab Al targets. By analyzing the emission spectra, the temporally and spatially resolved electron density and electron temperature at the stagnation layer were extracted, with a time resolution of 10 ns. Data analysis confirms that the electron density of the stagnation layer evolves over a longer timescale than in the single plume case. On the other hand, the temperature trends show that the electron temperature decreases much more rapidly at the stagnation layer than in the case for the single expanding plasma. In addition, a Langmuir probe was used to investigate the properties of the collisional front evolution. The overall experimental results show that colliding laser produced plasmas could be useful in the design of experiments devoted to fusion reaction rate measurements in a low energy domain by including the effect of the electron screening (ES).

  19. Utility of intracardiac ultrasound imaging to guide pulmonary vein ablation using laser balloon catheter.

    Science.gov (United States)

    Leite, Luiz; Su, Wilber; Johnson, Susan B; Milton, Mark; Henz, Benhur; Sarabanda, Alvaro; Santos, Simone N; Packer, Douglas L

    2009-12-01

    Pulmonary vein isolation (PVI) with balloon catheter has been used as the endpoint for AF ablation. To determine the usefulness of intracardiac ultrasound (ICUS) to guide PVI using laser balloon catheter. 59 PVs were ablated in 27 dogs. Doppler imaging was used to identify blood flow leaks between PV and balloon. After each energy delivery, the circular mapping catheter was repositioned to check if isolation had been achieved. The leak position was then correlated with the gap position at the pathological study. Multivariate logistic regression analysis was undertaken. 59 PV were ablated. Mean burn time was 279+/-177 sec, mean balloon diameter was 23+/-3 mm, and mean balloon length was 25+/-4 mm. Complete isolation was achieved in 38/59 (64%) cases, and it was significantly more common when there was no leak: [30/38 (79%) versus 8/23 (35%), p<0.001]. This occurred regardless of time of laser application (302+/-223 sec. vs. 266+/-148 sec., p=ns), laser power (3.5 W/cm, 4.5 W/cm, and 5.5 W/cm), balloon diameter (24+/- 3 mm vs. 22+/- 3 mm, p=ns) and length (27+/-4 mm vs. 24+/-4mm, p=ns). The positive predictive value for predicting incomplete isolation was 65% and the negative predictive value was 83%. An identifiable leak between PV and the LBA device seen at the ICUS is predictive of lower PV isolation rates. ICUS may be useful for leak detection to avoid ineffective energy application during circumferential PV ablation. This could also be helpful when other types of energy are used.

  20. Influence of water layer thickness on hard tissue ablation with pulsed CO2 laser

    Science.gov (United States)

    Zhang, Xianzeng; Zhan, Zhenlin; Liu, Haishan; Zhao, Haibin; Xie, Shusen; Ye, Qing

    2012-03-01

    The theory of hard tissue ablation reported for IR lasers is based on a process of thermomechanical interaction, which is explained by the absorption of the radiation in the water component of the tissue. The microexplosion of the water is the cause of tissue fragments being blasted from hard tissue. The aim of this study is to evaluate the influence of the interdependence of water layer thickness and incident radiant exposure on ablation performance. A total of 282 specimens of bovine shank bone were irradiated with a pulse CO2 laser. Irradiation was carried out in groups: without a water layer and with a static water layer of thickness ranging from 0.2 to 1.2 mm. Each group was subdivided into five subgroups for different radiant exposures ranging from 18 to 84 J/cm2, respectively. The incision geometry, surface morphology, and microstructure of the cut walls as well as thermal injury were examined as a function of the water layer thickness at different radiant exposures. Our results demonstrate that the additional water layer is actually a mediator of laser-tissue interaction. There exists a critical thickness of water layer for a given radiant exposure, at which the additional water layer plays multiple roles, not only acting as a cleaner to produce a clean cut but also as a coolant to prevent bone heating and reduce thermal injury, but also helping to improve the regularity of the cut shape, smooth the cut surface, and enhance ablation rate and efficiency. The results suggest that desired ablation results depend on optimal selection of both water layer thickness and radiant exposure.

  1. Reflectance confocal microscopy-guided laser ablation of basal cell carcinomas: initial clinical experience

    Science.gov (United States)

    Sierra, Heidy; Yélamos, Oriol; Cordova, Miguel; Chen, Chih-Shan Jason; Rajadhyaksha, Milind

    2017-08-01

    Laser ablation offers a procedure for precise, fast, and minimally invasive removal of superficial and early nodular basal cell carcinomas (BCCs). However, the lack of histopathological confirmation has been a limitation toward widespread use in the clinic. A reflectance confocal microscopy (RCM) imaging-guided approach offers cellular-level histopathology-like feedback directly on the patient, which may then guide and help improve the efficacy of the ablation procedure. Following an ex vivo benchtop study (reported in our earlier papers), we performed an initial study on 44 BCCs on 21 patients in vivo, using a pulsed erbium:ytterbium aluminum garnet laser and a contrast agent (aluminum chloride). In 10 lesions on six patients, the RCM imaging-guided detection of either presence of residual tumor or complete clearance was immediately confirmed with histopathology. Additionally, 34 BCCs on 15 patients were treated with RCM imaging-guided laser ablation, with immediate confirmation for clearance of tumor (no histopathology), followed by longer-term monitoring, currently in progress, with follow-up imaging (again, no histopathology) at 3, 6, and 18 months. Thus far, the imaging resolution appears to be sufficient and consistent for monitoring efficacy of ablation in the wound, both immediately postablation and subsequently during recovery. The efficacy results appear to be promising, with observed clearance in 19 cases of 22 cases with follow-ups ranging from 6 to 21 months. An additional 12 cases with 1 to 3 months of follow-ups has shown clearance of tumor but a longer follow-up time is required to establish conclusive results. Further instrumentation development will be necessary to cover larger areas with a more automatically controlled instrument for more uniform, faster, and deeper imaging of margins.

  2. Multi-criteria optimization in CO2 laser ablation of multimode polymer waveguides

    Science.gov (United States)

    Tamrin, K. F.; Zakariyah, S. S.; Sheikh, N. A.

    2015-12-01

    High interconnection density associated with current electronics products poses certain challenges in designing circuit boards. Methods, including laser-assisted microvia drilling and surface mount technologies for example, are being used to minimize the impacts of the problems. However, the bottleneck is significantly pronounced at bit data rates above 10 Gbit/s where losses, especially those due to crosstalk, become high. One solution is optical interconnections (OI) based on polymer waveguides. Laser ablation of the optical waveguides is viewed as a very compatible technique with ultraviolet laser sources, such as excimer and UV Nd:YAG lasers, being used due to their photochemical nature and minimal thermal effect when they interact with optical materials. In this paper, the authors demonstrate the application of grey relational analysis to determine the optimized processing parameters concerning fabrication of multimode optical polymer waveguides by using infra-red 10.6 μm CO2 laser micromachining to etch acrylate-based photopolymer (Truemode™). CO2 laser micromachining offers a low cost and high speed fabrication route needed for high volume productions as the wavelength of CO2 lasers can couple well with a variety of polymer substrates. Based on the highest grey relational grade, the optimized processing parameters are determined at laser power of 3 W and scanning speed of 100 mm/s.

  3. Micro-scale novel stable isotope fractionation during weathering disclosed by femtosecond laser ablation

    Science.gov (United States)

    Schuessler, J. A.; von Blanckenburg, F.

    2012-12-01

    The stable isotope fractionation of metals and metalloids during chemical weathering and alteration of rocks at low temperature is a topic receiving increasing scientific attention. For these systems, weathering of primary minerals leads to selective partitioning of isotopes between the secondary minerals formed from them, and the dissolved phase of soil or river water. While the isotopic signatures of these processes have been mapped-out at the catchment or the soil scale, the actual isotopic fractionation is occurring at the mineral scale. To identify the processes underlying such micro-scale fractionation, the development of micro-analytical tools allows to investigate mechanisms of isotope fractionation in-situ, in combination with textural information of weathering reactions. We have developed a second-generation UV femtosecond (fs) laser system at GFZ Potsdam. The advantage of UV-fs laser ablation is the reduction of laser-induced isotopic and elemental fractionation by avoiding 'thermal effects' during ablation, such that accurate isotope ratios can be measured by standard-sample-standard bracketing using laser ablation multicollector ICP-MS; where the matrix of the bracketing standard does not need to match that of the sample [1]. Our system consists of the latest generation femtosecond solid-state laser (Newport Spectra Physics Solstice), producing an ultra short pulse width of about 100 femtoseconds at a wavelength of 196 nm. The system is combined with a custom-build computer-controlled sample stage and allows fully automated isotope analyses through synchronised operation of the laser with the Neptune MC-ICP-MS. To assess precision and accuracy of our laser ablation method, we analysed various geological reference materials. We obtained δ30Si values of -0.31 ± 0.23 (2SD, n = 13) for basalt glass BHVO-2G, and -1.25 ± 0.21 (2SD, n = 27) for pure Si IRMM17 when bracketed against NBS-28 quartz. δ56Fe and δ26Mg values obtained from non-matrix matched

  4. Laser structuring of metallic mold inserts by using μs, ns, and ps-laser ablation

    Science.gov (United States)

    Scholz, Steffen G.; Kolew, Alexander; Griffiths, Christian

    2012-03-01

    Bio-inspired surfaces targeting functional characteristics such as anti-reflectivity, self-cleaning effects or a drag reduction are of significant interest to industry. In this feasibility study, process chains for the mass production of so-called shark skin structured surfaces are investigated. Due to their drag reduction properties, such bio-inspired surfaces are of relevance to a number of applications in which particular aqua- and aerodynamic characteristics are required. The design of the shark skin structure relies on a bio-mimetic analytical model to generate the 3D surface model necessary to achieve the targeted surface functionality. The process chains presented combine laser ablation as a method for micro structuring masters for high throughput replication employing injection molding. In particular, three different process chains that rely on micro second (μs), nano second (ns) and pico second (ps) laser ablation systems to pattern mold inserts were investigated. Then, these inserts were integrated into a tool for micro injection molding and replication trials were carried out. The results show that all three laser sources can be utilized to create this kind of micro cavities. This research indicates that these micro structures can be replicated successfully, but further work is required to optimize the replication and laser structuring process.

  5. Transmission Geometry Laser Ablation into a Non-Contact Liquid Vortex Capture Probe for Mass Spectrometry Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Ovchinnikova, Olga S [ORNL; Bhandari, Deepak [ORNL; Lorenz, Matthias [ORNL; Van Berkel, Gary J [ORNL

    2014-01-01

    RATIONALE: Capture of material from a laser ablation plume into a continuous flow stream of solvent provides the means for uninterrupted sampling, transport and ionization of collected material for coupling with mass spectral analysis. Reported here is the use of vertically aligned transmission geometry laser ablation in combination with a new non-contact liquid vortex capture probe coupled with electrospray ionization for spot sampling and chemical imaging with mass spectrometry. Methods: A vertically aligned continuous flow liquid vortex capture probe was positioned directly underneath a sample surface in a transmission geometry laser ablation (355 nm, 10 Hz, 7 ns pulse width) setup to capture into solution the ablated material. The outlet of the vortex probe was coupled to the Turbo V ion source of an AB SCIEX TripleTOF 5600+ mass spectrometer. System operation and performance metrics were tested using inked patterns and thin tissue sections. Glass slides and slides designed especially for laser capture microdissection, viz., DIRECTOR slides and PEN 1.0 (polyethylene naphthalate) membrane slides, were used as sample substrates. Results: The estimated capture efficiency of laser ablated material was 24%, which was enabled by the use of a probe with large liquid surface area (~ 2.8 mm2) and with gravity to help direct ablated material vertically down towards the probe. The swirling vortex action of the liquid surface potentially enhanced capture and dissolution of not only particulates, but also gaseous products of the laser ablation. The use of DIRECTOR slides and PEN 1.0 (polyethylene naphthalate) membrane slides as sample substrates enabled effective ablation of a wide range of sample types (basic blue 7, polypropylene glycol, insulin and cyctochrome c) without photodamage using a UV laser. Imaging resolution of about 6 m was demonstrated for stamped ink on DIRECTOR slides based on the ability to distinguish features present both in the optical and in the

  6. Thermal activation in KrF laser ablation of CuCl

    Science.gov (United States)

    Kuper, S.; Brannon, J.

    1994-07-01

    248 nm excimer abaltion of carefully prepared CuCi samples is reported, and shown to occur by a predominantly thermal mechanism. Using a quartz-crystal microbalance (QCM) to monitor abaltion, a precise detailed plot of single-pulse mass removal versus incident fluence was obtained for fluences up to 150 mJ/sq cm. A two-parameter Arrhenius exponential function was found to fit the experimental abaltion data. Calculations of laser-induced surface heating were caried out by use of a finite-difference heating code, formulated in terms of enthalpy. Ablation was observed to commence at a fluence of 25 mJ/sq cm, where the calculated surface temperature is approximately 910 K-some 200 K above the melting point. Dynamic ablation was included in the finite-difference calculation by allowing the position of the CuCl surface Xi to vary in time. The best data fit is provided by the zeroth-order kinetic equation: d Xi/dt = (16 A/ns)exp(-38 kJ/mole)/RT(sub Xi) where T(sub Xi) is the surface temperature. A thermodynamic calculation shows the average heat of CuCl vaporization in the temperature range from 900 to 2000 K to be near the fit of value of 38 kJ/mole. From plots of the ablation depth versus time, the CuCl surface was estimated to recede during the ablation at rates up to 10 cm/s.

  7. A randomized prospective long-term (>1 year) clinical trial comparing the efficacy and safety of radiofrequency ablation to 980 nm laser ablation of the great saphenous vein.

    Science.gov (United States)

    Sydnor, Malcolm; Mavropoulos, John; Slobodnik, Natalia; Wolfe, Luke; Strife, Brian; Komorowski, Daniel

    2017-07-01

    Purpose To compare the short- and long-term (>1 year) efficacy and safety of radiofrequency ablation (ClosureFAST™) versus endovenous laser ablation (980 nm diode laser) for the treatment of superficial venous insufficiency of the great saphenous vein. Materials and methods Two hundred patients with superficial venous insufficiency of the great saphenous vein were randomized to receive either radiofrequency ablation or endovenous laser ablation (and simultaneous adjunctive therapies for surface varicosities when appropriate). Post-treatment sonographic and clinical assessment was conducted at one week, six weeks, and six months for closure, complications, and patient satisfaction. Clinical assessment of each patient was conducted at one year and then at yearly intervals for patient satisfaction. Results Post-procedure pain ( p radiofrequency ablation group. Improvements in venous clinical severity score were noted through six months in both groups (endovenous laser ablation 6.6 to 1; radiofrequency ablation 6.2 to 1) with no significant difference in venous clinical severity score ( p = 0.4066) or measured adverse effects; 89 endovenous laser ablation and 87 radiofrequency patients were interviewed at least 12 months out with a mean long-term follow-up of 44 and 42 months ( p = 0.1096), respectively. There were four treatment failures in each group, and every case was correctable with further treatment. Overall, there were no significant differences with regard to patient satisfaction between radiofrequency ablation and endovenous laser ablation ( p = 0.3009). There were no cases of deep venous thrombosis in either group at any time during this study. Conclusions Radiofrequency ablation and endovenous laser ablation are highly effective and safe from both anatomic and clinical standpoints over a multi-year period and neither modality achieved superiority over the other.

  8. Target current: a useful parameter for characterizing laser ablation

    Czech Academy of Sciences Publication Activity Database

    Krása, Josef; Giuffreda, E.; Delle Side, D.; Nassisi, V.; Klír, Daniel; Cikhardt, Jakub; Řezáč, Karel

    2017-01-01

    Roč. 35, č. 1 (2017), s. 170-176 ISSN 0263-0346 R&D Projects: GA ČR GA16-07036S; GA MŠk(CZ) LD14089; GA MŠk(CZ) LM2015083 Institutional support: RVO:68378271 ; RVO:61389021 Keywords : impurities on target surface * positive and negative target polarization * space structure of ion front * target current in laser-produced plasmas Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 1.420, year: 2016

  9. Measurement of ventilation- and perfusion-mediated cooling during laser ablation in ex vivo human lung tumors.

    Science.gov (United States)

    Vietze, Andrea; Koch, Franziska; Laskowski, Ulrich; Linder, Albert; Hosten, Norbert

    2011-11-01

    Perfusion-mediated tissue cooling has often been described in the literature for thermal ablation therapies of liver tumors. The objective of this study was to investigate the cooling effects of both perfusion and ventilation during laser ablation of lung malignancies. An ex vivo lung model was used to maintain near physiological conditions for the specimens. Fourteen human lung lobes containing only primary lung tumors (non-small cell lung cancer) were used. Laser ablation was carried out using a Nd:YAG laser with a wavelength of 1064 nm and laser fibers with 30 mm diffusing tips. Continuous invasive temperature measurement in 10 mm distance from the laser fiber was performed. Laser power was increased at 2 W increments starting at 10 W up to a maximum power of 12-20 W until a temperature plateau around 60 °C was reached at one sensor. Ventilation and perfusion were discontinued for 6 min each to assess their effects on temperature development. The experiments lead to 25 usable temperature profiles. A significant temperature increase was observed for both discontinued ventilation and perfusion. In 6 min without perfusion, the temperature rose about 5.5 °C (mean value, Pcooling are significant influencing factors on temperature development during thermal ablation. They should be taken into account during the planning and preparation of minimally invasive lung tumor treatment in order to achieve complete ablation. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  10. Near-infrared image-guided laser ablation of dental decay

    Science.gov (United States)

    Tao, You-Chen; Fried, Daniel

    2009-09-01

    Image-guided laser ablation systems are now feasible for dentistry with the recent development of nondestructive high-contrast imaging modalities such as near-IR (NIR) imaging and optical coherence tomography (OCT) that are capable of discriminating between sound and demineralized dental enamel at the early stages of development. Our objective is to demonstrate that images of demineralized tooth surfaces have sufficient contrast to be used to guide a CO2 laser for the selective removal of natural and artificial caries lesions. NIR imaging and polarization-sensitive optical coherence tomography (PS-OCT) operating at 1310-nm are used to acquire images of natural lesions on extracted human teeth and highly patterned artificial lesions produced on bovine enamel. NIR and PS-OCT images are analyzed and converted to binary maps designating the areas on the samples to be removed by a CO2 laser to selectively remove the lesions. Postablation NIR and PS-OCT images confirmed preferential removal of demineralized areas with minimal damage to sound enamel areas. These promising results suggest that NIR and PS-OCT imaging systems can be integrated with a CO2 laser ablation system for the selective removal of dental caries.

  11. Effect of ambient pressure on laser ablation and plume expansion dynamics: A numerical simulation

    International Nuclear Information System (INIS)

    Chen Zhaoyang; Bleiner, Davide; Bogaerts, Annemie

    2006-01-01

    A comprehensive numerical model is applied to the study of the effect of ambient pressure in laser ablation, more specifically on the copper target heating, melting and vaporization, and the resulting plume expansion in the helium gas, as well as on plasma formation in the plume. Under the laser pulse condition investigated [5 ns full width at half maximum (FWHM) and 10 9 W/cm 2 peak irradiance], the calculated results show that the characteristics of the surface temperature and the evaporation depth are very similar even when the ambient pressure varies greatly. The influence of the ambient pressure on the fraction of absorbed laser energy is also small. The maximum ablated material vapor density in the plume is influenced slightly by the different pressures. Before 40 ns, the maximum plume temperature for various ambient pressures is in the order of a few 10 4 K. However, the effect of ambient pressure on the plume length is quite large. A specific calculation for a Gaussian-shaped laser pulse with 6 ns FWHM and 2.76x10 9 W/cm 2 peak irradiance is made. The calculated evaporation depth agrees well with the experimental data. Therefore, the model can be useful to predict trends in target and plume (plasma) characteristics, which are difficult to obtain experimentally for various ambient pressures

  12. Production of TiO2 crystalline nanoparticles by laser ablation in ethanol

    International Nuclear Information System (INIS)

    Boutinguiza, M.; Rodriguez-Gonzalez, B.; Val, J. del; Comesaña, R.; Lusquiños, F.; Pou, J.

    2012-01-01

    Highlights: ► Nanoparticles of TiO 2 have been obtained by laser ablation of Ti submerged in ethanol using CW laser. ► The use of CW laser contributes to control the size distribution and to complete oxidation. ► The particles formation mechanism is the melting and rapid solidification. - Abstract: TiO 2 nanoparticles have received a special attention due to their applications in many different fields, such as catalysis, biomedical engineering, and energy conversion in solar cells. In this paper we report on the production of TiO 2 nanoparticles by means of a pulsed laser to ablate titanium metallic target submerged in ethanol. The results show that titanium crystalline dioxide nanoparticles can be obtained in a narrow size distribution. Crystalline phases, morphology and optical properties of the obtained colloidal nanoparticles were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and UV/vis absorption spectroscopy. The produced particles consisted mainly of titanium oxide crystalline nanoparticles showing spherical shape with most diameters ranging from 5 to 50 nm. Nanoparticles are polycrystalline exhibiting the coexistence of the three main phases with the predominance of brookite.

  13. Improving adhesion of copper/epoxy joints by pulsed laser ablation

    KAUST Repository

    Hernandez, Edwin

    2015-10-19

    The purpose of the present work is to analyze the effect of pulsed laser ablation on copper substrates (CuZn40) deployed for adhesive bonding. Surface pre-treatment was carried using an Yb-fiber laser beam. Treated surfaces were probed using Scanning Electron Microscopy (SEM) and X-Ray Photoelectron Spectroscopy (XPS). The mechanical performance of CuZn40/epoxy bonded joints was assessed using the T-peel test coupon. In order to resolve the mechanisms of failure and adhesive penetration within surface asperities induced by the laser treatment, fracture surfaces were surveyed using SEM. Finite element simulations, based on the use of the cohesive zone model of fracture, were carried out to evaluate the variation of bond toughness. Results indicated that the laser ablation process effectively modifies surface morphology and chemistry and enables enhanced mechanical interlocking and cohesive failure within the adhesive layer. Remarkable improvements of apparent peel energy and bond toughness were observed with respect to control samples with sanded substrates.

  14. Formation of plasmonic colloidal silver for flexible and printed electronics using laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Kassavetis, S., E-mail: skasa@physics.auth.gr [University of Ioannina, Department of Materials Science and Engineering, 45110 Ioannina (Greece); Kaziannis, S. [University of Ioannina, Department of Physics, 45110 Ioannina (Greece); Pliatsikas, N. [University of Ioannina, Department of Materials Science and Engineering, 45110 Ioannina (Greece); Aristotle University of Thessaloniki, Department of Physics, 54124 Thessaloniki (Greece); Avgeropoulos, A.; Karantzalis, A.E. [University of Ioannina, Department of Materials Science and Engineering, 45110 Ioannina (Greece); Kosmidis, C. [University of Ioannina, Department of Physics, 45110 Ioannina (Greece); Lidorikis, E. [University of Ioannina, Department of Materials Science and Engineering, 45110 Ioannina (Greece); Patsalas, P. [Aristotle University of Thessaloniki, Department of Physics, 54124 Thessaloniki (Greece)

    2015-05-01

    Highlights: • Silver plasmonic colloidal in organic solvents by ps laser ablation process. • Ag NPs that meet size requirements of the printed organic electronics technology. • Ag NPs size refinement by secondary process using the 355 nm beam of a ns laser. - Abstract: Laser ablation (LA) in liquids has been used for the development of various nanoparticles (NPs); among them, Ag NPs in aqueous solutions (usually produced by nanosecond (ns) LA) have attracted exceptional interest due to its strong plasmonic response. In this work, we present a comprehensive study of the LA of Ag in water, chloroform and toluene, with and without PVP, using a picosecond (ps) Nd:YAG laser and we consider a wide range of LA parameters such as the laser wavelength (1064, 532, 355 nm), the pulse energy (0.3–17 mJ) and the number of pulses. In addition, we consider the use of a secondary nanosecond laser beam for the refinement of the NPs size distribution. The optical properties of the NPs were evaluated by in situ optical transmittance measurements in the UV–vis spectral ranges. The morphology of the NPs and the formation of aggregates were investigated by Scanning Electron Microscopy and High-Resolution Transmission Electron Microscopy. The ps LA process resulted in the development of bigger Ag NPs, compared to the ns LA, compatible with the size requirements of the printed organic electronics technology. The optimum conditions for the ps LA of Ag in organic solvents include the use of the 355 nm beam at low pulse energy (<1 mJ); these conditions rendered isolated Ag nanoparticles manifesting strong and well defined surface plasmon resonance peak. The use of the secondary ns laser beam was proven to be able to refine the nanoparticles to intermediate size between those produced by the single ns or ps LA.

  15. Supra-threshold epidermis injury from near-infrared laser radiation prior to ablation onset

    Science.gov (United States)

    DeLisi, Michael P.; Peterson, Amanda M.; Lile, Lily A.; Noojin, Gary D.; Shingledecker, Aurora D.; Stolarski, David J.; Zohner, Justin J.; Kumru, Semih S.; Thomas, Robert J.

    2017-02-01

    With continued advancement of solid-state laser technology, high-energy lasers operating in the near-infrared (NIR) band are being applied in an increasing number of manufacturing techniques and medical treatments. Safety-related investigations of potentially harmful laser interaction with skin are commonplace, consisting of establishing the maximum permissible exposure (MPE) thresholds under various conditions, often utilizing the minimally-visible lesion (MVL) metric as an indication of damage. Likewise, characterization of ablation onset and velocity is of interest for therapeutic and surgical use, and concerns exceptionally high irradiance levels. However, skin injury response between these two exposure ranges is not well understood. This study utilized a 1070-nm Yb-doped, diode-pumped fiber laser to explore the response of excised porcine skin tissue to high-energy exposures within the supra-threshold injury region without inducing ablation. Concurrent high-speed videography was employed to assess the effect on the epidermis, with a dichotomous response determination given for three progressive damage event categories: observable permanent distortion on the surface, formation of an epidermal bubble due to bounded intra-cutaneous water vaporization, and rupture of said bubble during laser exposure. ED50 values were calculated for these categories under various pulse configurations and beam diameters, and logistic regression models predicted injury events with approximately 90% accuracy. The distinction of skin response into categories of increasing degrees of damage expands the current understanding of high-energy laser safety while also underlining the unique biophysical effects during induced water phase change in tissue. These observations could prove useful in augmenting biothermomechanical models of laser exposure in the supra-threshold region.

  16. Particulates reduction in laser-ablated YBa2Cu3O7-δ thin films by laser-induced plume heating

    International Nuclear Information System (INIS)

    Koren, G.; Baseman, R.J.; Gupta, A.; Lutwyche, M.I.; Laibowitz, R.B.

    1990-01-01

    Experimental demonstration of reduction in the number and size of particulates formed in the laser ablation deposition of YBa 2 Cu 3 O 7-δ thin films is obtained by the use of a second laser which further heats and fragments the blowoff material in the plume formed by the first laser. This results in a smoother film with higher critical current density as compared to that obtained without the second laser irradiation of the plume

  17. Growth of anatase and rutile phase TiO{sub 2} nanoparticles using pulsed laser ablation in liquid: Influence of surfactant addition and ablation time variation

    Energy Technology Data Exchange (ETDEWEB)

    Chaturvedi, Amita, E-mail: amita-chaturvedi@rrcat.gov.in [Laser Material Processing Division, Raja Ramanna Centre for Advanced Technology, Indore 452013, MP (India); Joshi, M.P. [Laser Material Processing Division, Raja Ramanna Centre for Advanced Technology, Indore 452013, MP (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai – 400094 (India); Mondal, P.; Sinha, A.K.; Srivastava, A.K. [Indus Synchrotron Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore 452013, MP (India)

    2017-02-28

    Highlights: • Ablations of Ti metal target were carried out in DI water and in 0.001 M SDS solution for different times using PLAL process. • Different characterization studies have been carried out to confirm the growth of TiO{sub 2} nanoparticles in both the liquid mediums. • Anatase phase TiO{sub 2} nanoparticles were obtained in DI water and rutile phase in 0.001 M SDS aqueous solution. • In surfactant solution, longer time ablation leads depletion of SDS molecules causes growth of anatase phase for 90 min. • Our studies confirmed the role of liquid ambience conditions variation over the different phase formations of nanoparticles. - Abstract: Titanium dioxide (TiO{sub 2}) nanoparticles were grown using nanosecond pulsed laser ablation of Ti target in DI water and in 0.001 M sodium dodecyl sulfate (SDS) surfactant aqueous solution. Growth was carried out with varying ablation times i. e. 30 min, 60 min and 90 min. The objective of our study was to investigate the influence of variations in liquid ambience conditions on the growth of the nanoparticles in a pulsed laser ablation in liquid (PLAL) process. Size, composition and optical properties of the grown TiO{sub 2} nanoparticles were investigated using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), optical absorption, photoluminescence (PL) spectroscopy and X-ray diffraction (XRD) studies. The obtained nanoparticles of TiO{sub 2} were found almost spherical in shape and polycrystalline in nature in both the liquid mediums i.e. DI water and aqueous solution of surfactant. Nanoparticles number density was also found to increase with increasing ablation time in both the liquid mediums. However crystalline phase of the grown TiO{sub 2} nanoparticles differs with the change in liquid ambience conditions. Selected area electron diffraction (SAED), PL and XRD studies suggest that DI water ambience is favorable for the growth of anatase phase TiO{sub 2} nanoparticles for all

  18. Low level laser intensity improves propulsive appliance effects on condylar cartilage

    Science.gov (United States)

    Figueiredo, Augusto C. R.; dos Santos, Fernanda C. A.; Capeletti, Lucas R.; Galdino, Marcos V. B.; Araújo, Renan V.; Marques, Mara R.

    2012-01-01

    Mandibular propulsive appliance (MPA) stimulates cell proliferation and gene expression on mandible condylar cartilage (Marques et al., 2008). However, its association with low level laser therapy (LLLT) is unknown. This study evaluated the effects of LLLT associated to MPA on mandibular condyle. Twenty Wistar rats were divided into four groups. Group I received any treatment. Group II was bilaterally irradiated on temporomandibular joint with 10 J/cm2 low level laser (780nm, 40mW and 10s) on alternate days. Group III used the propulsive appliance for ten hours daily and Group IV used the appliance daily and was irradiated on alternate days. After 15 days the animals were killed by lethal doses of anesthetics. The condyles were fixed in Methacarn solution and decalcified in 4.13% EDTA solution for 30 days. Seriate saggital 5 μm-thick sections were stained by the hematoxilin-eosin method. Morphological and morphometric analyses were performed to measure the length and the height of the mandibular condyle, the thickness of the condilar cartilage and the bone mass. Results were expressed as mean +/- standard deviation (one-way ANOVA, Tukey's post-test.) The appliance increased all measures compared to the control group, except bone mass. Alone, LLLT had no effects on all measures, however, the association of the appliance with the LLLT increased condylar cartilage and bone mass significantly compared to the others groups. These results suggest that LLLT improves the effects of mandibular propulsive appliance in the condylar cartilage growth and formation of bone mass.

  19. Selective removal of esthetic composite restorations with spectral guided laser ablation

    Science.gov (United States)

    Yi, Ivana; Chan, Kenneth H.; Tsuji, Grant H.; Staninec, Michal; Darling, Cynthia L.; Fried, Daniel

    2016-02-01

    Dental composites are used for a wide range of applications such as fillings for cavities, adhesives for orthodontic brackets, and closure of gaps (diastemas) between teeth by esthetic bonding. Anterior restorations are used to replace missing, diseased and unsightly tooth structure for both appearance and function. When these restorations must be replaced, they are difficult to remove mechanically without causing excessive removal or damage to enamel because dental composites are color matched to teeth. Previous studies have shown that CO2 lasers have high ablation selectivity and are well suited for removal of composite on occlusal surfaces while minimizing healthy tissue loss. A spectral feedback guidance system may be used to discriminate between dental composite and dental hard tissue for selective ablation of composite material. The removal of composite restorations filling diastemas is more challenging due to the esthetic concern for anterior teeth. The objective of this study is to determine if composite spanning a diastema between anterior teeth can be removed by spectral guided laser ablation at clinically relevant rates with minimal damage to peripheral healthy tissue and with higher selectivity than a high speed dental handpiece.

  20. X-ray microtomography and laser ablation in the analysis of ink distribution in coated paper

    Science.gov (United States)

    Myllys, M.; Häkkänen, H.; Korppi-Tommola, J.; Backfolk, K.; Sirviö, P.; Timonen, J.

    2015-04-01

    A novel method was developed for studying the ink-paper interface and the structural variations of a deposited layer of ink. Combining high-resolution x-ray tomography with laser ablation, the depth profile of ink (toner), i.e., its varying thickness, could be determined in a paper substrate. X-ray tomography was used to produce the 3D structure of paper with about 1 μm spatial resolution. Laser ablation combined with optical imaging was used to produce the 3D structure of the printed layer of ink on top of that paper with about 70 nm depth resolution. Ablation depth was calibrated with an optical profilometer. It can be concluded that a toner layer on a light-weight-coated paper substrate was strongly perturbed by protruding fibers of the base paper. Such fibers together with the surface topography of the base paper seem to be the major factors that control the leveling of toner and its penetration into a thinly coated paper substrate.