WorldWideScience

Sample records for laser-induced hole filling

  1. Standard methods for filled hole tension testing of textile composites

    Science.gov (United States)

    Portanova, M. A.; Masters, J. E.

    1995-01-01

    The effects of two test specimen geometry parameters, the specimen width and W/D ratio, on filled-hole tensile strength were determined for textile composite materials. Test data generated by Boeing and Lockheed on 2-D and 3-D braids, and 3-D weaves were used to make these evaluations. The investigation indicated that filled-hole tensile-strength showed little sensitivity to either parameter. Test specimen configurations used in open-hole tension tests, such as those suggested by ASTM D5766 - Standard Test Method for Open Hole Tensile Strength of Polymer Matrix Composite Laminates or those proposed by MIL-HDBK-17-lD should provide adequate results for material comparisons studies. Comparisons of the materials' open-hole and filled-hole tensile strengths indicated that the latter were generally lower than the former. The 3-D braids were the exception; their filled-hole strengths were unexpected larger than their open-hole strengths. However, these increases were small compared to the scatter in the data. Thus, filled hole tension may be a critical design consideration for textile composite materials.

  2. Two-dimensional photonic crystals from semiconductor material with polymer filled holes

    NARCIS (Netherlands)

    Van der Heijden, R.; Kjellander, C.; Carlström, C.-F.; Snijders, J.; Van der Heijden, R.W.; Bastiaansen, K.; Broer, D.; Karouta, F.; Nötzel, R.; Van der Drift, E.

    2006-01-01

    Polymer filling of the air holes of indiumphosphide based two-dimensional photonic crystals is reported. The filling is performed by infiltration with a liquid monomer and solidification of the infill in situ by thermal polymerization. Complete hole filling is obtained with infiltration under ambien

  3. Two-dimensional photonic crystals from semiconductor material with polymer filled holes

    Science.gov (United States)

    van der Heijden, Rob; Kjellander, Charlotte; Carlström, Carl-Fredrik; Snijders, Juri; van der Heijden, Rob W.; Bastiaansen, Kees; Broer, Dick; Karouta, Fouad; Nötzel, Richard; van der Drift, Emile; Salemink, Huub W. M.

    2006-04-01

    Polymer filling of the air holes of indiumphosphide based two-dimensional photonic crystals is reported. The filling is performed by infiltration with a liquid monomer and solidification of the infill in situ by thermal polymerization. Complete hole filling is obtained with infiltration under ambient pressure. This conclusion is based both on cross-sectional scanning electron microscope inspection of the filled samples as well as on optical transmission measurements.

  4. Algorithm of Detecting and Filling Small Holes in Triangular Mesh Surface

    Institute of Scientific and Technical Information of China (English)

    ZHOU Dong-sheng; JIANG Chao; DONG Jing; LIU Rui

    2014-01-01

    In some scattered point cloud triangular mesh restoration algorithm, small triangular mesh holes problem will often affect the quality of the model. For small holes at the details, this paper propose a method for identifying and extracting hollow edge,and use a triangle growth way based on boundary edge angle to fill the empty void. First, according the relationship of the point, side and face of the triangle mesh model to identify the hole, then extracting the holes boundary edge and classifying it. Finally, using a triangle growth method based on holes boundary edge angle to fill each small holes separated from the boundary. Compared with other algorithm of filling holes, this method is high efficiency for small holes of smooth surface,and itimprovesthe quality of the triangular mesh model.

  5. Filling the holes: Evolving excised binary black hole initial data with puncture techniques

    CERN Document Server

    Etienne, Zachariah B; Liu, Yuk Tung; Shapiro, Stuart L; Baumgarte, Thomas W

    2007-01-01

    We follow the inspiral and merger of equal-mass black holes (BHs) by the moving puncture technique and demonstrate that both the exterior solution and the asymptotic gravitational waveforms are unchanged when the initial interior solution is replaced by constraint-violating ``junk'' initial data. We apply this result to evolve conformal thin-sandwich (CTS) binary BH initial data by filling their excised interiors with arbitrary, but smooth, initial data and evolving with standard puncture gauge choices. The waveforms generated for both puncture and filled-CTS initial data are remarkably similar, and there are only minor differences between irrotational and corotational CTS BH binaries. Even the interior solutions appear to evolve to the same constraint-satisfying solution at late times, independent of the initial data.

  6. 3D Ultrasound Reconstruction of Spinal Images using an Improved Olympic Hole-Filling Method

    NARCIS (Netherlands)

    Dewi, D.E.O.; Wilkinson, M.H.F.; Mengko, T.L.R.; Purnama, I.K.E.; Ooijen, P.M.A. van; Veldhuizen, A.G.; Maurits, N.M.; Verkerke, G.J.

    2009-01-01

    We propose a new Hole-filling algorithm by improving the Olympic operator, and we also apply it to generate the volume in our freehand 3D ultrasound reconstruction of the spine. First, the ultrasound frames and position information are compounded into a 3D volume using the Bin-filling method. Then,

  7. A computationally efficient denoising and hole-filling method for depth image enhancement

    Science.gov (United States)

    Liu, Soulan; Chen, Chen; Kehtarnavaz, Nasser

    2016-04-01

    Depth maps captured by Kinect depth cameras are being widely used for 3D action recognition. However, such images often appear noisy and contain missing pixels or black holes. This paper presents a computationally efficient method for both denoising and hole-filling in depth images. The denoising is achieved by utilizing a combination of Gaussian kernel filtering and anisotropic filtering. The hole-filling is achieved by utilizing a combination of morphological filtering and zero block filtering. Experimental results using the publicly available datasets are provided indicating the superiority of the developed method in terms of both depth error and computational efficiency compared to three existing methods.

  8. Hole-Filling for DIBR Based on Depth and Gradient Information

    Directory of Open Access Journals (Sweden)

    Dan Wang

    2015-02-01

    Full Text Available Depth image-based rendering (DIBR is a method for generating new virtual images from known viewpoints. However, holes often appear in the rendered virtual images due to occlusion and inaccurate depth information. In this paper, we present a novel hole-filling algorithm to improve the image quality of DIBR. In the proposed method, depth information is added to the priority calculation function when determining the order of hole-filling. Then, the gradient information is used as auxiliary information when searching for the optimal matching block. Experimental results show that the proposed algorithm achieves better objective quality and also improves the subjective quality of the rendered images.

  9. Filling or draining a water bottle with two holes

    Science.gov (United States)

    Cross, Rod

    2016-07-01

    Three simple experiments are described using a small water bottle with two holes in the side of the bottle. The main challenge is to predict and then explain the observations, but the arrangements can also be used for quantitative measurements concerning hydrostatic pressure, Bernoulli’s equation, surface tension and bubble formation.

  10. Weiss oscillations and particle-hole symmetry at the half-filled Landau level

    CERN Document Server

    Cheung, Alfred K C; Mulligan, Michael

    2016-01-01

    Particle-hole symmetry in the lowest Landau level of the two-dimensional electron gas requires the electrical Hall conductivity to equal $\\pm e^2/2h$ at half-filling. We study the consequences of weakly broken particle-hole symmetry for magnetoresistance oscillations about half-filling in the presence of an applied periodic one-dimensional electrostatic potential. At fixed electron density, the oscillation minima are asymmetrically biased towards higher magnetic fields, while at fixed magnetic field, the oscillations occur symmetrically as the electron density is varied about half-filling. We find an approximate "sum rule" obeyed for all pairs of oscillation minima that can be tested in experiment. We discuss the implications of our results and approximations for the description of the half-filled Landau level.

  11. Development and application of a high-speed planar laser-induced fluorescence imaging system to evaluate liquid and vapor phases of sprays from a multi-hole diesel fuel injector

    Science.gov (United States)

    Parrish, S. E.; Zink, R. J.

    2013-02-01

    A high-speed imaging system capable of acquiring elastic scattering images and planar laser-induced fluorescence (PLIF) images in a near-simultaneous fashion has been developed. Acquiring both elastic scattering and PLIF images enables the liquid phase to be discriminated from the vapor phase. High-speed imaging allows the temporal evolution of flow structures to be evaluated. Images of sprays from a multi-hole diesel fuel injector operating under engine-like conditions were acquired. The vapor phase images reveal intricate fluid dynamic structures that exhibit a high degree of variability, indicative of a turbulent gas jet.

  12. Predation by odonates depresses mosquito abundance in water-filled tree holes in Panama.

    Science.gov (United States)

    Fincke, Ola M; Yanoviak, Stephen P; Hanschu, Richard D

    1997-10-01

    In the lowland moist forest of Barro Colorado Island (BCI), Panama, larvae of four common species of odonates, a mosquito, and a tadpole are the major predators in water-filled tree holes. Mosquito larvae are their most common prey. Holes colonized naturally by predators and prey had lower densities of mosquitoes if odonates were present than if they were absent. Using artificial tree holes placed in the field, we tested the effects of odonates on their mosquito prey while controlling for the quantity and species of predator, hole volume, and nutrient input. In large and small holes with low nutrient input, odonates depressed the number of mosquitoes present and the number that survived to pupation. Increasing nutrient input (and consequently, mosquito abundance) to abnormally high levels dampened the effect of predation when odonates were relatively small. However, the predators grew faster with higher nutrients, and large larvae in all three genera reduced the number of mosquitoes surviving to pupation, even though the abundance of mosquito larvae remained high. Size-selective predation by the odonates is a likely explanation for this result; large mosquito larvae were less abundant in the predator treatment than in the controls. Because species assemblages were similar between natural and artificial tree holes, our results suggest that odonates are keystone species in tree holes on BCI, where they are the most common large predators.

  13. Reversible electric field induced spectral hole filling in a doped polymer film

    Science.gov (United States)

    Gu, Wei; Hanson, David M.

    1988-09-01

    The effect of a dc electric field on persistent spectral holes in the absorption spectra of perylene doped polyvinyl butyral films has been measured. This effect is not like a typical Stark effect that is obtained with polymer films doped with polar dye molecules. Instead, a new phenomenon of reversible spectral hole filling is observed. This phenomenon is attributed to the elastic deformation of the interaction potentials of the dopant and the polymer associated with reversible field-induced tunneling in the intrinsic two-level systems. A quantitative theory of the phenomenon is proposed.

  14. Influence of Filling Medium of Holes on the Negative-Index Response of Sandwiched Metamaterials

    Institute of Scientific and Technical Information of China (English)

    WANG Xu-Dong; YE Yong-Hong; MA Ji; JIANG Mei-Ping

    2010-01-01

    @@ We numerically study the negative index properties of sandwiched metamaterials,perforated with a square array of circle holes filled with different media.Transmission spectra indicate that the filling medium can effectively change the position of the localized resonant peak,while keeping the position of the other transmission peaks hardly changed.Reflection spectra and retrieved effective impedance verify that an appropriate choice of the filling medium can provide a perfect impedance match.Due to the perfect impedance match,the electromagnetic responses of the negative index band based on the internal surface plasmon polaritons change in many aspects,such as a stronger magnetic resonance,a higher figure of merit and a narrower negative refractive index band.

  15. Acoustic hole filling for sparse enrollment data using a cohort universal corpus for speaker recognition.

    Science.gov (United States)

    Suh, Jun-Won; Hansen, John H L

    2012-02-01

    In this study, the problem of sparse enrollment data for in-set versus out-of-set speaker recognition is addressed. The challenge here is that both the training speaker data (5 s) and test material (2~6 s) is of limited test duration. The limited enrollment data result in a sparse acoustic model space for the desired speaker model. The focus of this study is on filling these acoustic holes by harvesting neighbor speaker information to leverage overall system performance. Acoustically similar speakers are selected from a separate available corpus via three different methods for speaker similarity measurement. The selected data from these similar acoustic speakers are exploited to fill the lack of phone coverage caused by the original sparse enrollment data. The proposed speaker modeling process mimics the naturally distributed acoustic space for conversational speech. The Gaussian mixture model (GMM) tagging process allows simulated natural conversation speech to be included for in-set speaker modeling, which maintains the original system requirement of text independent speaker recognition. A human listener evaluation is also performed to compare machine versus human speaker recognition performance, with machine performance of 95% compared to 72.2% accuracy for human in-set/out-of-set performance. Results show that for extreme sparse train/reference audio streams, human speaker recognition is not nearly as reliable as machine based speaker recognition. The proposed acoustic hole filling solution (MRNC) produces an averaging 7.42% relative improvement over a GMM-Cohort UBM baseline and a 19% relative improvement over the Eigenvoice baseline using the FISHER corpus.

  16. Geologic Characterization of Young Alluvial Basin-Fill Deposits from Drill Hole Data in Yucca Flat, Nye County, Nevada.

    Energy Technology Data Exchange (ETDEWEB)

    Donald S. Sweetkind; Ronald M. Drake II

    2007-01-22

    Yucca Flat is a topographic and structural basin in the northeastern part of the Nevada Test Site (NTS) in Nye County, Nevada, that has been the site of numerous underground nuclear tests; many of these tests occurred within the young alluvial basin-fill deposits. The migration of radionuclides to the Paleozoic carbonate aquifer involves passage through this thick, heterogeneous section of Tertiary and Quaternary rock. An understanding of the lateral and vertical changes in the material properties of young alluvial basin-fill deposits will aid in the further development of the hydrogeologic framework and the delineation of hydrostratigraphic units and hydraulic properties required for simulating ground-water flow in the Yucca Flat area. This report by the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, presents data and interpretation regarding the three-dimensional variability of the shallow alluvial aquifers in areas of testing at Yucca Flat, data that are potentially useful in the understanding of the subsurface flow system. This report includes a summary and interpretation of alluvial basin-fill stratigraphy in the Yucca Flat area based on drill hole data from 285 selected drill holes. Spatial variations in lithology and grain size of the Neogene basin-fill sediments can be established when data from numerous drill holes are considered together. Lithologic variations are related to different depositional environments within the basin including alluvial fan, channel, basin axis, and playa deposits.

  17. Geologic Characterization of Young Alluvial Basin-Fill Deposits from Drill-Hole Data in Yucca Flat, Nye County, Nevada

    Science.gov (United States)

    Sweetkind, Donald S.; Drake II, Ronald M.

    2007-01-01

    Yucca Flat is a topographic and structural basin in the northeastern part of the Nevada Test Site in Nye County, Nevada, that has been the site of numerous underground nuclear tests; many of these tests occurred within the young alluvial basin-fill deposits. The migration of radionuclides to the Paleozoic carbonate aquifer involves passage through this thick, heterogeneous section of Tertiary and Quaternary rock. An understanding of the lateral and vertical changes in the material properties of young alluvial basin-fill deposits will aid in the further development of the hydrogeologic framework and the delineation of hydrostratigraphic units and hydraulic properties required for simulating ground-water flow in the Yucca Flat area. This report by the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, presents data and interpretation regarding the three-dimensional variability of the shallow alluvial aquifers in areas of testing at Yucca Flat, data that are potentially useful in the understanding of the subsurface flow system. This report includes a summary and interpretation of alluvial basin-fill stratigraphy in the Yucca Flat area based on drill-hole data from 285 selected drill holes. Spatial variations in lithology and grain size of the Neogene basin-fill sediments can be established when data from numerous drill holes are considered together. Lithologic variations are related to different depositional environments within the basin such as alluvial fan, channel, basin axis, and playa deposits.

  18. Geologic Characterization of Young Alluvial Basin-Fill Deposits from Drill Hole Data in Yucca Flat, Nye County, Nevada

    Science.gov (United States)

    Sweetkind, Donald S.; Drake II, Ronald M.

    2007-01-01

    Yucca Flat is a topographic and structural basin in the northeastern part of the Nevada Test Site (NTS) in Nye County, Nevada, that has been the site of numerous underground nuclear tests; many of these tests occurred within the young alluvial basin-fill deposits. The migration of radionuclides to the Paleozoic carbonate aquifer involves passage through this thick, heterogeneous section of Tertiary and Quaternary rock. An understanding of the lateral and vertical changes in the material properties of young alluvial basin-fill deposits will aid in the further development of the hydrogeologic framework and the delineation of hydrostratigraphic units and hydraulic properties required for simulating ground-water flow in the Yucca Flat area. This report by the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, presents data and interpretation regarding the three-dimensional variability of the shallow alluvial aquifers in areas of testing at Yucca Flat, data that are potentially useful in the understanding of the subsurface flow system. This report includes a summary and interpretation of alluvial basin-fill stratigraphy in the Yucca Flat area based on drill hole data from 285 selected drill holes. Spatial variations in lithology and grain size of the Neogene basin-fill sediments can be established when data from numerous drill holes are considered together. Lithologic variations are related to different depositional environments within the basin including alluvial fan, channel, basin axis, and playa deposits.

  19. Laser-induced grating in ZnO

    DEFF Research Database (Denmark)

    Ravn, Jesper N.

    1992-01-01

    A simple approach for the calculation of self-diffraction in a thin combined phase and amplitude grating is presented. The third order nonlinearity, the electron-hole recombination time, and the ambipolar diffusion coefficient in a ZnO crystal are measured by means of laser-induced self-diffracti......A simple approach for the calculation of self-diffraction in a thin combined phase and amplitude grating is presented. The third order nonlinearity, the electron-hole recombination time, and the ambipolar diffusion coefficient in a ZnO crystal are measured by means of laser-induced self...

  20. The Effect of Hole Transport Material Pore Filling on Photovoltaic Performance in Solid-State Dye-Sensitized Solar Cells

    KAUST Repository

    Melas-Kyriazi, John

    2011-04-05

    A detailed investigation of the effect of hole transport material (HTM) pore filling on the photovoltaic performance of solid-state dye-sensitized solar cells (ss-DSCs) and the specific mechanisms involved is reported. It is demonstrated that the efficiency and photovoltaic characteristics of ss-DSCs improve with the pore filling fraction (PFF) of the HTM, 2,2\\',7,7\\'-tetrakis-(N, N-di-p-methoxyphenylamine)9,9\\'-spirobifluorene(spiro-OMeTAD). The mechanisms through which the improvement of photovoltaic characteristics takes place were studied with transient absorption spectroscopy and transient photovoltage/photocurrent measurements. It is shown that as the spiro-OMeTAD PFF is increased from 26% to 65%, there is a higher hole injection efficiency from dye cations to spiro-OMeTAD because more dye molecules are covered with spiro-OMeTAD, an order-of-magnitude slower recombination rate because holes can diffuse further away from the dye/HTM interface, and a 50% higher ambipolar diffusion coefficient due to an improved percolation network. Device simulations predict that if 100% PFF could be achieved for thicker devices, the efficiency of ss-DSCs using a conventional rutheniumdye would increase by 25% beyond its current value. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Particle-Hole Symmetry in the Fermion-Chern-Simons and Dirac Descriptions of a Half-Filled Landau Level

    Science.gov (United States)

    Wang, Chong; Cooper, Nigel R.; Halperin, Bertrand I.; Stern, Ady

    2017-07-01

    It is well known that there is a particle-hole symmetry for spin-polarized electrons with two-body interactions in a partially filled Landau level, which becomes exact in the limit where the cyclotron energy is large compared to the interaction strength; thus, one can ignore mixing between Landau levels. This symmetry is explicit in the description of a half-filled Landau level recently introduced by Son, using Dirac fermions, but it was thought to be absent in the older fermion-Chern-Simons approach, developed by Halperin, Lee, and Read (HLR) and subsequent authors. We show here, however, that when properly evaluated, the HLR theory gives results for long-wavelength low-energy physical properties—including the Hall conductance in the presence of impurities and the positions of minima in the magnetoroton spectra for fractional quantized Hall states close to half-filling—that are identical to predictions of the Dirac formulation. In fact, the HLR theory predicts an emergent particle-hole symmetry near half-filling, even when the cyclotron energy is finite.

  2. Electron backscatter diffraction analysis on the microstructures of electrolytic Cu deposition in the through hole filling process

    Energy Technology Data Exchange (ETDEWEB)

    Ho, C.E., E-mail: ceho1975@hotmail.com [Department of Chemical Engineering and Materials Science, Yuan Ze University, Taiwan, ROC (China); Liao, C.W. [Department of Chemical Engineering and Materials Science, Yuan Ze University, Taiwan, ROC (China); School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072 (China); Pan, C.X. [School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072 (China); Chen, H.J. [Department of Chemical Engineering and Materials Science, Yuan Ze University, Taiwan, ROC (China); Kuo, J.C.; Chen, D. [Department of Materials Science and Engineering, National Cheng Kung University, Taiwan, ROC (China)

    2013-10-01

    Through hole (TH) filling by electrolytic Cu deposition has become a critical process for high density interconnection technologies associated with three-dimensional packaging. In this study, the morphological and crystallographic evolutions of the electrolytic Cu TH filling with the plating time (t) were investigated using an optical microscope and a field-emission scanning electron microscope equipped with an electron backscatter diffraction (EBSD) analysis system. The Cu deposition rate in the TH was strongly dependent on t, which was established at a moderate rate of ∼ 0.3 μm/min at t = 40 min–74 min, then dramatically accelerated to ∼ 4 μm/min at t = 74 min–80 min (termed “fast deposition regime”), and subsequently decelerated in the final plating regime (t = 80 min–100 min). EBSD analyses showed that the electrolytic Cu predominantly possessed high-angle grain boundaries with strong coincidence site lattices at ∑3 (60° rotation at <111>) and ∑9 (38.9° rotation at <101>) for all t examined. Interestingly, the [111]‖TD (transverse direction) orientation displayed a relatively strong presence in the initial induction regime, while the [111]‖TD + [101]‖TD orientations with large grain sizes became dominant in the fast deposition regime (i.e., t = 74 min–80 min), and there was a very low concentration of the [111]‖TD orientation in the final deposition regime. This research offered a better understanding of the morphological and crystallographic evolutions in each stage of the electrolytic Cu TH filling. - Highlights: • Through hole (TH) filling by electrolytic Cu deposition • The Cu deposition rate is strongly dependent on the plating time in the THs. • The dominant Cu orientations were [111]‖TD (transverse direction) and [101]‖TD. • Cu possessed high angle grain boundaries with strong coincidence site lattices.

  3. ESA's high-energy observatories spot doughnut-shaped cloud with a black-hole filling

    Science.gov (United States)

    2004-07-01

    hi-res Size hi-res: 7265 KB Credits: ESA, V. Beckmann (GSFC) Doughnut-shaped cloud surrounds black hole This artist's impression shows the thick dust torus that astronomers believe surrounds supermassive black holes and their accretion discs, like the one harboured in the nucleus of the spiral galaxy NGC 4388. When the torus is seen `edge-on’ as in this case, the visible light emitted by the accretion disc is partially blocked. However, the sharp X-ray and gamma-ray eyes of XMM-Newton and Integral can peer through the thick dust and see how the energy released by the accretion disc interacts with and is absorbed by the torus. Black holes are objects so compact and with gravity so strong that not even light can escape from them. Scientists think that `supermassive’ black holes are located in the cores of most galaxies, including our Milky Way galaxy. They can contain the mass of thousands of millions of suns, confined within a region no larger than our Solar System. They appear to be surrounded by a hot, thin disk of accreting gas and, farther out, the thick doughnut-shaped torus. Depending on the inclination of the torus, it can hide the black hole and the hot accretion disc from the line of sight. Galaxies in which a torus blocks the light from the central accretion disc are called `Seyfert 2’ types and are usually faint to optical telescopes. Another theory, however, is that these galaxies appear rather faint because the central black hole is not actively accreting gas and the disc surrounding it is therefore faint. An international team of astronomers led by Dr Volker Beckmann, Goddard Space Flight Center (Greenbelt, USA) has studied one of the nearest objects of this type, a spiral galaxy called NGC 4388, located 65 million light years away in the constellation Virgo. Since NGC 4388 is relatively close, and therefore unusually bright for its class, it is easier to study. Astronomers often study black holes that are aligned face-on, thus avoiding the

  4. Exploring the Landscape of Modern Academic Psychology: Finding and Filling the Holes

    Science.gov (United States)

    Rozin, Paul

    2007-01-01

    Like any other domain of human activity, psychology has its fads and fashions. One consequence of fads is an overconcentration of resources on specific problems or approaches, which leaves other important problems or approaches (holes) underappreciated and understudied. This article is primarily about different factors (such as negativity bias,…

  5. Qualitative Analysis of Teeth and Evaluation of Amalgam Elements Penetration into Dental Matrix Using Laser Induced Breakdown Spectroscopy

    Science.gov (United States)

    Gazmeh, Meisam; Bahreini, Maryam; Tavassoli, Seyed Hassan; Asnaashari, Mohammad

    2015-01-01

    Introduction: In this study, laser induced breakdown spectroscopy (LIBS) is used for qualitative analysis of healthy and carious teeth. The technique of laser ablation is receiving increasing attention for applications in dentistry, specifically for the treatment of teeth such as drilling of micro-holes and plaque removal. Methods: A quality-switched (Q-switched) Neodymium-Doped Yttrium Aluminium Garnet (Nd:YAG) laser operating at wavelength of 1064 nm, pulse energy of 90 mJ/pulse, repetition rate of 2Hz and pulse duration of 6 ns was used in this analysis. In the process of ablation a luminous micro-plasma is normally generated which may be exploited for on-line elemental analysis via laser induced breakdown spectroscopy technique. We propose laser induced breakdown spectroscopy as a rapid, in situ and easy method for monitoring drilling process. Results: The results of elemental analysis show the presence of some trace elements in teeth including P, Ca, Mg, Zn, K, Sr, C, Na, H, O and the permeability of some amalgam (teeth filling materials) elements including Hg, Ag, Cu and Sn into dental matrix. Conclusion: This study addresses the ability of LIBS in elemental analysis of teeth and its feasibility in acute identification of healthy and carious teeth during drilling process for future clinical applications. PMID:25987971

  6. Particle-hole symmetry and electromagnetic response of a half-filled Landau level

    Science.gov (United States)

    Levin, Michael; Son, Dam Thanh

    2017-03-01

    We derive exact physical consequences of particle-hole symmetry of the ν =1 /2 state of electrons in a strong magnetic field. We show that if the symmetry is not spontaneously broken, the Hall conductivity and the susceptibility satisfy an exact relationship, valid at any wave number and frequencies much below the cyclotron frequency. The relationship holds for clean systems and also for systems with statistically particle-hole symmetric disorder. We work out the constraints this relationship imposes on the theory of the Dirac composite fermion. We also argue that that the exact relationship is violated in the Halperin-Lee-Read (HLR) field theory and present an explicit calculation within a Galilean invariant mean-field approximation to the HLR theory to illustrate the breakdown.

  7. Experimental Verification of the Use of Metal Filled Via Hole Fences for Crosstalk Control of Microstrip Lines in LTCC Packages

    Science.gov (United States)

    Ponchak, George E.; Chun, Donghoon; Yook, Jong-Gwan; Katehi, Linda P. B.

    2001-01-01

    Coupling between microstrip lines in dense RF packages is a common problem that degrades circuit performance. Prior three-dimensional-finite element method (3-D-FEM) electromagnetic simulations have shown that metal filled via hole fences between two adjacent microstrip lines actually Increases coupling between the lines: however, if the top of the via posts are connected by a metal strip, coupling is reduced. In this paper, experimental verification of the 3-D-FEM simulations is demonstrated for commercially fabricated low temperature cofired ceramic (LTCC) packages. In addition, measured attenuation of microstrip lines surrounded by the shielding structures is presented and shows that shielding structures do not change the attenuation characteristics of the line.

  8. In vitro evaluation of a modified 4-META/MMA-TBB resin for filling access holes of screw-retained implant prostheses.

    Science.gov (United States)

    Tanimura, Remy; Suzuki, Shiro

    2015-07-01

    This study evaluates a modified 4-META/MMA-TBB resin (M4M) as a candidate material for filling screw-retained implant access hole. Its characteristics were compared with a conventional composite resin (CR) with or without a bonding agent (BA) or a ceramic primer (CP). Ceramic blocks were divided into five groups, including (A) CR, (B) CR with BA, (C) CR with CP and BA, (D) M4M, and (E) M4M with CP. Shear bond strengths were measured after 5000 times of thermocycling. Groups A, B, and D were excluded from further tests as they showed no adhesion. A cylindrical cavity (2.5 mm diameter, 3 mm depth) simulating access hole was prepared in a ceramic block and glazed to evaluate micro-leakage and wear test of groups C and E. The results were statistically analyzed with Mann-Whitney test (p  fill the ceramic access holes of the implant upper structure.

  9. High fill factor polymer solar cells incorporating a low temperature solution processed WO{sub 3} hole extraction layer

    Energy Technology Data Exchange (ETDEWEB)

    Stubhan, Tobias; Li, Ning; Matt, Gebhard J. [Institute of Materials for Electronics and Energy Technology (I-MEET), Friedrich-Alexander-University Erlangen-Nuremberg, Martensstrasse 7, 91058 Erlangen (Germany); Luechinger, Norman A.; Halim, Samuel C. [Nanograde Llc., Wolfgang-Pauli-Strasse, P/O Box 239, 8093 Zurich (Switzerland); Brabec, Christoph J. [Institute of Materials for Electronics and Energy Technology (I-MEET), Friedrich-Alexander-University Erlangen-Nuremberg, Martensstrasse 7, 91058 Erlangen (Germany); Bavarian Center for Applied Energy Research (ZAE Bayern), Haberstrasse 2a, 91058 Erlangen (Germany)

    2012-12-15

    We demonstrate solution-processed tungsten trioxide (WO{sub 3}) incorporated as hole extraction layer (HEL) in polymer solar cells (PSCs) with active layers comprising either poly(3-hexylthiophene) (P3HT) or poly[(4,4'-bis(2-ethylhexyl)dithieno[3,2-b:2',3'-d]silole)-2,6-diyl-alt-(4,7-bis(2-thienyl)-2,1,3-benzothiadiazole)-5,50-diyl] (Si-PCPDTBT) mixed with a fullerene derivative. The WO{sub 3} layers are deposited from an alcohol-based, surfactant-free nanoparticle solution. A short, low-temperature (80 C) annealing is sufficient to result in fully functional films without the need for an oxygen-plasma treatment. This allows the application of the WO{sub 3} buffer layer in normal as well as inverted architecture solar cells. Normal architecture devices based on WO{sub 3} HELs show comparable performance to the PEDOT:PSS reference devices with slightly better fill factors and open circuit voltages. Very high shunt resistances (over 1 M{Omega} cm{sup 2}) and excellent diode rectification underline the charge selectivity of the solution-processed WO{sub 3} layers. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Filling the Holes: Work Schedulers as Job Crafters of Employment Practice in Long-Term Health Care.

    Science.gov (United States)

    Kossek, Ellen Ernst; Piszczek, Matthew M; Mcalpine, Kristie L; Hammer, Leslie B; Burke, Lisa

    2016-08-01

    Although work schedulers serve an organizational role influencing decisions about balancing conflicting stakeholder interests over schedules and staffing, scheduling has primarily been described as an objective activity or individual job characteristic. The authors use the lens of job crafting to examine how schedulers in 26 health care facilities enact their roles as they "fill holes" to schedule workers. Qualitative analysis of interview data suggests that schedulers expand their formal scope and influence to meet their interpretations of how to manage stakeholders (employers, workers, and patients). The authors analyze variations in the extent of job crafting (cognitive, physical, relational) to broaden role repertoires. They find evidence that some schedulers engage in rule-bound interpretation to avoid role expansion. They also identify four types of schedulers: enforcers, patient-focused schedulers, employee-focused schedulers, and balancers. The article adds to the job-crafting literature by showing that job crafting is conducted not only to create meaningful work but also to manage conflicting demands and to mediate among the competing labor interests of workers, clients, and employers.

  11. Evaluation of Interlaminar Stresses in Composite Laminates with a Bolt-Filled Hole Using a Linear Elastic Traction-Separation Description

    Directory of Open Access Journals (Sweden)

    Yong Cao

    2017-01-01

    Full Text Available Determination of the local interlaminar stress distribution in a laminate with a bolt-filled hole is helpful for optimal bolted joint design, due to the three-dimensional (3D nature of the stress field near the bolt hole. A new interlaminar stress distribution phenomenon induced by the bolt-head and clamp-up load, which occurs in a filled-hole composite laminate, is investigated. In order to efficiently evaluate interlaminar stresses under the complex boundary condition, a calculation strategy that using zero-thickness cohesive interface element is presented and validated. The interface element is based on a linear elastic traction-separation description. It is found that the interlaminar stress concentrations occur at the hole edge, as well as the interior of the laminate near the periphery of the bolt head. In addition, the interlaminar stresses near the periphery of the bolt head increased with an increase in the clamp-up load, and the interlaminar normal and shear stresses are not at the same circular position. Therefore, the clamp-up load cannot improve the interlaminar stress distribution in the laminate near the periphery of the bolt head, although it can reduce the magnitude of the interlaminar shear stress at the hole edge. Thus, the interlaminar stress distribution phenomena may lead to delamination initiation in the laminate near the periphery of the bolt head, and should be considered in composite bolted joint design.

  12. Treatment of Laser-Induced Retinal Injuries

    Science.gov (United States)

    1989-06-29

    Distribution List (enclosed) bI’TF rruIoN STATEMEN A Approved for publi reljaso Disatbunon Unlimited TREATMENT OF LASER-INDUCED RETINAL INJURIES FINAL...suprathreshold retinal laser lesions II. Subthreshold retinal laser lesions III. Effect of steroid treatment on laser-induced retinal injury Discussion and...In the present study we investigated the effect of corticosteroid treatment of argon laser-induced retinal injury on vitreal accumulation of both

  13. Influence of pressure conditions and back-filling materials on the durability of bore-hole ground loops; Lebensdauer von Erdwaermesonden in Bezug auf Druckverhaeltnisse und Hinterfuellung

    Energy Technology Data Exchange (ETDEWEB)

    Rohner, R. [E. Rohner, Arnegg (Switzerland); Rybach, L.; Salton, M. [Swiss Federal Institute of Technology (ETHZ), Institut fuer Geophysik, Zuerich (Switzerland)

    2001-07-01

    This final report for the Swiss Federal Office of Energy (SFOE) discusses the influence of the relatively high pressures found in ground loops at depths of more than 200 metres and the effects caused by overloading the ground loops. The latter can cause the back-filling between the ground loop and the surrounding rock to freeze. The report describes tests carried out on 70-metre and 265-metre deep test bore-hole installations. The results of investigations into the influence of such pressure conditions on the materials of the ground loop and their service life are presented. The results are also compared with simulations using the FRACTure and EED calculation programmes. Details are given on the bore-holes with respect to their geology and construction. The report concludes that bore-hole ground loops can be considered as being very robust components with a long service life, provided they are designed and installed according to accepted professional standards.

  14. The size and structure of the laser entrance hole in gas-filled hohlraums at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, M. B., E-mail: schneider5@llnl.gov; MacLaren, S. A.; Widmann, K.; Meezan, N. B.; Hammer, J. H.; Yoxall, B. E.; Bell, P. M.; Benedetti, L. R.; Bradley, D. K.; Callahan, D. A.; Dewald, E. L.; Döppner, T.; Eder, D. C.; Edwards, M. J.; Hinkel, D. E.; Hsing, W. W.; Kervin, M. L.; Landen, O. L.; Lindl, J. D.; May, M. J. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); and others

    2015-12-15

    At the National Ignition Facility, a thermal X-ray drive is created by laser energy from 192 beams heating the inside walls of a gold cylinder called a “hohlraum.” The x-ray drive heats and implodes a fuel capsule. The laser beams enter the hohlraum via laser entrance holes (LEHs) at each end. The LEH radius decreases as heated plasma from the LEH material blows radially inward but this is largely balanced by hot plasma from the high-intensity region in the center of the LEH pushing radially outward. The x-ray drive on the capsule is deduced by measuring the time evolution and spectra of the x-radiation coming out of the LEH and correcting for geometry and for the radius of the LEH. Previously, the LEH radius was measured using time-integrated images in an x-ray band of 3–5 keV (outside the thermal x-ray region). For gas-filled hohlraums, the measurements showed that the LEH radius is larger than that predicted by the standard High Flux radiation-hydrodynamic model by about 10%. A new platform using a truncated hohlraum (“ViewFactor hohlraum”) is described, which allows time-resolved measurements of the LEH radius at thermal x-ray energies from two views, from outside the hohlraum and from inside the hohlraum. These measurements show that the LEH radius closes during the low power part of the pulse but opens up again at peak power. The LEH radius at peak power is larger than that predicted by the models by about 15%–20% and does not change very much with time. In addition, time-resolved images in a >4 keV (non-thermal) x-ray band show a ring of hot, optically thin gold plasma just inside the optically thick LEH plasma. The structure of this plasma varies with time and with Cross Beam Energy Transfer.

  15. Laser-Induced Energy Transfer in Solids

    NARCIS (Netherlands)

    Morsink, J.B.W.; Rullmann, Johan; Wiersma, Douwe

    1981-01-01

    Laser-induced energy transfer was observed and studied in the system pentacene doped into naphthalene. The transfer spectrum shows a remarkable correspondence with the host density of states function. The rate for laser-induced energy transfer is given and it is concluded that most likely, intermole

  16. High conductivity Ag-based metal organic complexes as dopant-free hole-transport materials for perovskite solar cells with high fill factors.

    Science.gov (United States)

    Hua, Yong; Xu, Bo; Liu, Peng; Chen, Hong; Tian, Haining; Cheng, Ming; Kloo, Lars; Sun, Licheng

    2016-04-21

    Hole-transport materials (HTMs) play an important role as hole scavenger materials in the most efficient perovskite solar cells (PSCs). Here, for the first time, two Ag-based metal organic complexes (HA1 and HA2) are employed as a new class of dopant-free hole-transport material for application in PSCs. These HTMs show excellent conductivity and hole-transport mobility. Consequently, the devices based on these two HTMs exhibit unusually high fill factors of 0.76 for HA1 and 0.78 for HA2, which are significantly higher than that obtained using spiro-OMeTAD (0.69). The cell based on HA1-HTM in its pristine form achieved a high power conversion efficiency of 11.98% under air conditions, which is comparable to the PCE of the cell employing the well-known doped spiro-MeOTAD (12.27%) under the same conditions. More importantly, their facile synthesis and purification without using column chromatography makes these new silver-based HTMs highly promising for future commercial applications of PSCs. These results provide a new way to develop more low-cost and high conductivity metal-complex based HTMs for efficient PSCs.

  17. Laser-induced damage in optical materials

    CERN Document Server

    Ristau, Detlev

    2014-01-01

    Dedicated to users and developers of high-powered systems, Laser-Induced Damage in Optical Materials focuses on the research field of laser-induced damage and explores the significant and steady growth of applications for high-power lasers in the academic, industrial, and military arenas. Written by renowned experts in the field, this book concentrates on the major topics of laser-induced damage in optical materials and most specifically addresses research in laser damage that occurs in the bulk and on the surface or the coating of optical components. It considers key issues in the field of hi

  18. Advancing Front Method in Triangular Meshes Hole-Filling Application%波前法在三角网格孔洞修补中的应用

    Institute of Scientific and Technical Information of China (English)

    王小超; 曹俊杰; 刘秀平; 李宝军

    2011-01-01

    In order to restore the missing shape of holes in triangular meshes, especially big ones locating at a high curved region, a hole-filling algorithm based on advancing front method is proposed in this paper.After detecting the boundary of holes, normals of the boundary vertices are well estimated.Combining the normals with the Laplacian coordinates, the boundary vertices are classified into two types: concave and convex.Then, based on the normal, the concavity-convexity feature of each boundary vertex and a proper adjustment parameter, optimal vertices are carefully computed and new triangles are created to fill holes.Many experimental results show that our method has powerful ability to recover the missing shape with high quality triangular meshes for even big holes located at the high curved region.Without post-processing, such as refinement and smoothing, the hole-filing meshes obtained by our method interpolate the shape and have consistent mesh distribution and smooth transition with the surrounding meshes.%为了有效地修补出三角网格中缺失部分的形状,针对弯曲较大的大面积缺失孔洞,提出一种基于波前法的孔洞修补算法.在提取孔洞边界后,首先估计出相对准确的边界点法向,结合Laplacian坐标对边界点进行凹凸性分类;利用边界点的法向和凹凸性信息适当选取控制参数,计算合理的新增顶点位置,并生成新的三角网格,以实现对孔洞的修补.实验结果表明,该算法对弯曲较大的大面积缺失孔洞有较好的修补效果;在未经后续优化处理的情况下,如细化、光顺等,修补网格的顶点密度与原有网格相近,并且与原有网格之间自然过渡.

  19. Surgical Treatment of Laser Induced Eye Injuries

    Science.gov (United States)

    1990-12-05

    AD-A234 849 CONTRACT NO.: DAMD17-89-C-9026 TITLE: SURGICAL TREATMENT OF LASER INDUCED EYE INJURIES AUTHORS: Leonard M. Hjelmeland, Maurice B. Landers...62787A 62787A878 BA JDA318205 11. TITLE (Include Secirity Classification) (U) Surgical Treatment of Laser Induced Eye Injuries 12. PERSONAL AUTHOR(S...TERMS (Continue on reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP RA 3; Lasers; Eye injury ; Surgery 09 03 06 04 19. ABSTRACT

  20. Toxicity of Sulfide and Ammonium to Aedes triseriatus Larvae (Diptera: Culicidae) in Water-Filled Tree Holes and Tires.

    Science.gov (United States)

    Walker, Edward D

    2016-05-01

    Ammonium and sulfide in water of tree hole and tire habitats of Aedes triseriatus Say larvae could accumulate to toxic levels, limiting growth and production of larvae and adults. Both ions were detected in water samples taken in longitudinal series over 11 dates from 10 habitats of each type during the larval growth season, at concentrations suggestive of reducing conditions in these habitats. Ammonium was more concentrated overall in water of both habitat types, while sulfide was more concentrated in tires than in tree holes. Water of tree holes was more acidic, whereas water in tires tended to be more basic, an important difference relative to the tendency of ammonium to form the more toxic ammonia moiety under basic conditions. Oxygen saturation was low in both habitat types, indicative of hypoxic conditions such that aerobic respiration would be limited. First-and fourth-instar larvae were sensitive to ammonium and sulfide in acute dose-response assays, but LC50 values were above maximum concentrations observed under field conditions, suggesting that toxic effects of ammonium and sulfide on larvae are not acute, but could be chronic.

  1. Study of the pore filling fraction of carbazole-based hole-transporting materials in solid-state dye-sensitized solar cells

    Directory of Open Access Journals (Sweden)

    Marwa Ben Manaa

    2016-07-01

    Full Text Available Carbazole-based molecular glasses have emerged as a promising alternative to the widely used hole-transporting materials (HTM spiro-OMeTAD in solid-state dye-sensitized solar cells (DSSCs. The pore filling fraction (PFF of the mesoporous TiO2 layer by the HTM appears as a key parameter determining the final efficiency of a DSSC. In this work, the pore-filling properties of a family of carbazole-based HTMs are investigated for the first time and the photovoltaic behavior of DSSC devices (fabricated using the D102 dye is discussed in light of the present findings. It is found that N-aryl substituted 3,6-bis(diphenylaminyl-carbazole derivatives exhibit relatively low PFF of ca. 60%. Methoxy groups on the diphenylamine moieties have little influence on the PFF, indicating that the strong enhancement in power conversion efficiency (PCE is not related to an improved filling of the pores by the HTM. N-alkylated HTMs lead to higher PFF, increasing with the alkyl chain length, up to 78%.

  2. Treatment of Laser Induced Retinal Injuries.

    Science.gov (United States)

    1986-04-02

    END 1.0 1.18 Yl(-ROCOPY Ri yjTuION If ’,! (HART !. UIH; iLruud @ N TREATMENT OF LASER INDUCED RETINAL INJURIES (ANNUAL REPORT 00 DTIC Michael Belkin...NO. CCESSION NO _______________________________61102A I102BS1O0 CF 1i. 446 TITLE (Indude S*.curny Claifkaion) TREATMENT OF LASER INDUCED RETINAL... INJURIES PERSONAL AUTHOR(S) M. BELKIN N. NAVEH a. TYPE OF REPORT 13b. TIME COVERED 14. DATE OF REPORT (Year, Mont. D y) S. PAGE COUNT FROM Xaj& TO l 2Ann

  3. Laser-induced breakdown spectroscopy of tantalum plasma

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Sidra; Bashir, Shazia; Hayat, Asma; Khaleeq-ur-Rahman, M.; Faizan–ul-Haq [Centre for Advanced Studies in Physics, GC University, Lahore (Pakistan)

    2013-07-15

    Laser Induced Breakdown spectroscopy (LIBS) of Tantalum (Ta) plasma has been investigated. For this purpose Q-switched Nd: YAG laser pulses (λ∼ 1064 nm, τ∼ 10 ns) of maximum pulse energy of 100 mJ have been employed as an ablation source. Ta targets were exposed under the ambient environment of various gases of Ar, mixture (CO{sub 2}: N{sub 2}: He), O{sub 2}, N{sub 2}, and He under various filling pressure. The emission spectrum of Ta is observed by using LIBS spectrometer. The emission intensity, excitation temperature, and electron number density of Ta plasma have been evaluated as a function of pressure for various gases. Our experimental results reveal that the optical emission intensity, the electron temperature and density are strongly dependent upon the nature and pressure of ambient environment. The SEM analysis of the ablated Ta target has also been carried out to explore the effect of ambient environment on the laser induced grown structures. The growth of grain like structures in case of molecular gases and cone-formation in case of inert gases is observed. The evaluated plasma parameters by LIBS analysis such as electron temperature and the electron density are well correlated with the surface modification of laser irradiated Ta revealed by SEM analysis.

  4. Laser induced white lighting of graphene foam

    Science.gov (United States)

    Strek, Wieslaw; Tomala, Robert; Lukaszewicz, Mikolaj; Cichy, Bartlomiej; Gerasymchuk, Yuriy; Gluchowski, Pawel; Marciniak, Lukasz; Bednarkiewicz, Artur; Hreniak, Dariusz

    2017-01-01

    Laser induced white light emission was observed from porous graphene foam irradiated with a focused continuous wave beam of the infrared laser diode. It was found that the intensity of the emission increases exponentially with increasing laser power density, having a saturation level at ca. 1.5 W and being characterized by stable emission conditions. It was also observed that the white light emission is spatially confined to the focal point dimensions of the illuminating laser light. Several other features of the laser induced white light emission were also discussed. It was observed that the white light emission is highly dependent on the electric field intensity, allowing one to modulate the emission intensity. The electric field intensity ca. 0.5 V/μm was able to decrease the white light intensity by half. Origins of the laser-induced white light emission along with its characteristic features were discussed in terms of avalanche multiphoton ionization, inter-valence charge transfer and possible plasma build-up processes. It is shown that the laser-induced white light emission may be well utilized in new types of white light sources.

  5. Laser induced white lighting of graphene foam

    Science.gov (United States)

    Strek, Wieslaw; Tomala, Robert; Lukaszewicz, Mikolaj; Cichy, Bartlomiej; Gerasymchuk, Yuriy; Gluchowski, Pawel; Marciniak, Lukasz; Bednarkiewicz, Artur; Hreniak, Dariusz

    2017-01-01

    Laser induced white light emission was observed from porous graphene foam irradiated with a focused continuous wave beam of the infrared laser diode. It was found that the intensity of the emission increases exponentially with increasing laser power density, having a saturation level at ca. 1.5 W and being characterized by stable emission conditions. It was also observed that the white light emission is spatially confined to the focal point dimensions of the illuminating laser light. Several other features of the laser induced white light emission were also discussed. It was observed that the white light emission is highly dependent on the electric field intensity, allowing one to modulate the emission intensity. The electric field intensity ca. 0.5 V/μm was able to decrease the white light intensity by half. Origins of the laser-induced white light emission along with its characteristic features were discussed in terms of avalanche multiphoton ionization, inter-valence charge transfer and possible plasma build-up processes. It is shown that the laser-induced white light emission may be well utilized in new types of white light sources. PMID:28112254

  6. Laser-induced tobacco protoplast fusion

    Institute of Scientific and Technical Information of China (English)

    李银妹; 关力劼; 楼立人; 崔国强; 姚湲; 王浩威; 操传顺; 鲁润龙; 陈曦

    1999-01-01

    Laser tweezers can manipulate small particles, such as cells and organdies. When coupling them with laser microbeam selective fusion of two tobacco protoplasts containing some chloroplast was achieved. Physical and biological variables that affect laser trapping and laser-induced fusion were also discussed. The results show that the effect of chloroplast content and distribution on the yield of cell fusion is remarkable.

  7. Modeling of laser induced periodic surface structures

    NARCIS (Netherlands)

    Skolski, J.Z.P.; Römer, G.R.B.E.; Huis in 't Veld, A.J.; Mitko, V.S.; Obona, J.V.; Ocelik, V.; Hosson, J.T.M. de

    2010-01-01

    In surfaces irradiated by short laser pulses, Laser Induced Periodic Surface Structures (LIPSS) have been observed on all kind of materials for over forty years. These LIPSS, also referred to as ripples, consist of wavy surfaces with periodicity equal or smaller than the wavelength of the laser radi

  8. A Spectral Analysis of Laser Induced Fluorescence of Iodine

    CERN Document Server

    Bayram, S B

    2015-01-01

    When optically excited, iodine absorbs in the 490- to 650-nm visible region of the spectrum and, after radiative relaxation, it displays an emission spectrum of discrete vibrational bands at moderate resolution. This makes laser-induced fuorescence spectrum of molecular iodine especially suitable to study the energy structure of homonuclear diatomic molecules at room temperature. In this spirit, we present a rather straightforward and inexpensive experimental setup and the associated spectral analysis which provides an excellent exercise of applied quantum mechanics fit for advanced laboratory courses. The students would be required to assign spectral lines, fill a Deslandres table, process the data to estimate the harmonic and anharmonic characteristics of the ground vibronic state involved in the radiative transitions, and thenceforth calculate a set of molecular constants and discuss a model of molecular vibrator.

  9. Meio- and Macrofaunal Communities in Artificial Water-Filled Tree Holes: Effects of Seasonality, Physical and Chemical Parameters, and Availability of Food Resources.

    Directory of Open Access Journals (Sweden)

    Christoph Ptatscheck

    Full Text Available In this study we investigated the dynamics of meiofaunal and macrofaunal communities in artificial water-filled tree holes. The abundances and, for the first time, biomasses and secondary production rates of these communities were examined. The experimental set-up consisted of 300 brown plastic cups placed in temperate mixed forests and sampled five times over a period of 16 months to determine the impact of (i seasonal events, (ii physicochemical parameters, and (iii food resources on the tree hole metazoans.Metazoan organisms, especially the meiofauna (rotifers and nematodes occupied nearly all of the cups (> 99% throughout the year. Between 55% and 99% of the metazoan community was represented by rotifers (max. 557,000 individuals 100 cm-2 and nematodes (max. 58,000 individuals 100 cm-2. Diptera taxa, particularly Dasyhelea sp. (max. 256 individuals 100 cm-2 dominated the macrofaunal community. Macrofauna accounted for the majority of the metazoan biomass, with a mean dry weight of 5,800 μg 100 cm-2 and an annual production rate of 20,400 μg C 100 cm-2, whereas for meiofauna mean biomass and annual production were 100 μg 100 cm-2 and 5,300 μg C 100 cm-2, respectively. The macrofaunal taxa tended to show more fluctuating population dynamic while the meiofaunal dynamic was rather low with partly asynchronous development. Seasonality (average temperature and rain intervals had a significant impact on both meiofauna and macrofauna. Furthermore, bottom-up control (chlorophyll-a and organic carbon, mainly attributable to algae, was a significant factor that shaped the metazoan communities. In contrast, physicochemical water parameters had no evident influence. 23.7% of organism density distribution was explained by redundancy analysis (RDA indicating a high dynamic and asynchrony of the systems.

  10. Laser-Induced Breakdown Spectroscopy in Africa

    Directory of Open Access Journals (Sweden)

    M. A. Kasem

    2015-01-01

    Full Text Available Laser-induced breakdown spectroscopy (LIBS, known also as laser-induced plasma spectroscopy (LIPS, is a well-known spectrochemical elemental analysis technique. The field of LIBS has been rapidly matured as a consequence of growing interest in real-time analysis across a broad spectrum of applied sciences and recent development of commercial LIBS analytical systems. In this brief review, we introduce the contributions of the research groups in the African continent in the field of the fundamentals and applications of LIBS. As it will be shown, the fast development of LIBS in Africa during the last decade was mainly due to the broad environmental, industrial, archaeological, and biomedical applications of this technique.

  11. Laser induced breakdown spectroscopy on meteorites

    Energy Technology Data Exchange (ETDEWEB)

    De Giacomo, A. [Department of Chemistry, University of Bari (Italy); MIP-CNR sec Bari (Italy)], E-mail: alessandro.degiacomo@ba.imip.cnr.it; Dell' Aglio, M.; De Pascale, O. [MIP-CNR sec Bari (Italy); Longo, S.; Capitelli, M. [Department of Chemistry, University of Bari (Italy); MIP-CNR sec Bari (Italy)

    2007-12-15

    The classification of meteorites when geological analysis is unfeasible is generally made by the spectral line emission ratio of some characteristic elements. Indeed when a meteorite impacts Earth's atmosphere, hot plasma is generated, as a consequence of the braking effect of air, with the consequent ablation of the falling body. Usually, by the plasma emission spectrum, the meteorite composition is determined, assuming the Boltzmann equilibrium. The plasma generated during Laser Induced Breakdown Spectroscopy (LIBS) experiment shows similar characteristics and allows one to verify the mentioned method with higher accuracy. On the other hand the study of Laser Induced Breakdown Spectroscopy on meteorite can be useful for both improving meteorite classification methods and developing on-flight techniques for asteroid investigation. In this paper certified meteorites belonging to different typologies have been investigated by LIBS: Dofhar 461 (lunar meteorite), Chondrite L6 (stony meteorite), Dofhar 019 (Mars meteorite) and Sikhote Alin (irony meteorite)

  12. 基于轮廓的 kinect 深度图像的空洞填补%KINECT DEPTH IMAGE HOLE FILLING BASED ON CONTOUR

    Institute of Scientific and Technical Information of China (English)

    操宣鹏; 陈一民

    2016-01-01

    For the noise characteristics of depth map obtained by Kinect and the problems of existing denoising algorithm,we presented a contour-based adaptive asymmetric Gaussian filtering methods (OAAG).This method,aiming at the characteristic of Kinect that it can obtain the depth image and colour image simultaneously,uses colour image to find objects’contour in the scene.When filling the depth,it selects the appropriate points with contour.Since the selected points are asymmetric,so it needs to change the symmetry of Gaussian filtering. Moreover,it changes the scale of Gaussian filtering to make it vary along with the changes of depth value of the area to be filled,this enables the Gaussian filtering to be adaptive.It is demonstrated through experimental comparison that the method can accurately fill the hole of depth image,and meanwhile it can well protect the edge information of image as well.%针对 Kinect 获得深度图噪声的特点,以及现有去噪算法存在的问题,提出一种基于轮廓的自适应非对称高斯滤波方法。该方法针对 Kinect 能够同时获得深度图像和彩色图像的特点,利用彩色图找到场景中物体的轮廓;在对深度图进行填补时,利用轮廓选取合适的有效点;选取的有效点是非对称的,所以需要改变高斯滤波的对称性;另外,改变高斯滤波的尺度,使其随着被填补区域深度值的变化而变化,使得高斯滤波具有自适应特性。通过实验对比,表明该方法能准确地填补深度图的空洞,同时还能很好地保护图像中边缘信息。

  13. 定向钻进及随钻测量技术在充填孔施工中的应用%Application of Directional Drilling and MWD Technology in the Filling Hole Construction

    Institute of Scientific and Technical Information of China (English)

    程红文

    2015-01-01

    Filling hole is a kind of vertical drilling hole with high precision, drilling hole trajectory can not be controlled by the conventional drilling method under the conditions of formation deflection-promoting and large natural bending.By using directional drilling and MWD technology, the drilling trajectory in the whole construction process can be monitored and ex-tended according to the trajectory design.The paper introduces the design of directional drilling, MWD, drilling hole straightening and sidetracking in the filling hole construction.%充填钻孔是一种高精度垂直孔,地层促斜、钻孔自然弯曲率较大时,常规钻进方法难以控制钻孔轨迹。在施工中应用定向钻进及随钻测量技术,则可以对钻孔实施全程轨迹监控,使其按照设计轨迹延伸。主要介绍了广西华锡集团股份有限公司铜坑矿将充填站充填孔施工中定向钻进设计、随钻测量、纠斜、侧钻等技术及工艺等。

  14. Laser induced forward transfer of soft materials

    Science.gov (United States)

    Palla-Papavlu, A.; Dinca, V.; Luculescu, C.; Shaw-Stewart, J.; Nagel, M.; Lippert, T.; Dinescu, M.

    2010-12-01

    A strong research effort is presently aimed at patterning methodologies for obtaining controlled defined micrometric polymeric structures for a wide range of applications, including electronics, optoelectronics, sensors, medicine etc. Lasers have been identified as appropriate tools for processing of different materials, such as ceramics and metals, but also for soft, easily damageable materials (biological compounds and polymers). In this work we study the dynamics of laser induced forward transfer (LIFT) with a gap between the donor and the receiver substrates, which is the basis for possible applications that require multilayer depositions with high spatial resolution.

  15. Laser induced fluorescence technique for environmental applications

    Science.gov (United States)

    Utkin, Andrei B.; Felizardo, Rui; Gameiro, Carla; Matos, Ana R.; Cartaxana, Paulo

    2014-08-01

    We discuss the development of laser induced fluorescence sensors and their application in the evaluation of water pollution and physiological status of higher plants and algae. The sensors were built on the basis of reliable and robust solid-state Nd:YAG lasers. They demonstrated good efficiency in: i) detecting and characterizing oil spills and dissolved organic matter; ii) evaluating the impact of stress on higher plants (cork oak, maritime pine, and genetically modified Arabidopsis); iii) tracking biomass changes in intertidal microphytobenthos; and iv) mapping macroalgal communities in the Tagus Estuary.

  16. Laser-induced breakdown spectroscopy in Asia

    Science.gov (United States)

    Wang, Zhen-Zhen; Deguchi, Yoshihiro; Zhang, Zhen-Zhen; Wang, Zhe; Zeng, Xiao-Yan; Yan, Jun-Jie

    2016-12-01

    Laser-induced breakdown spectroscopy (LIBS) is an analytical detection technique based on atomic emission spectroscopy to measure the elemental composition. LIBS has been extensively studied and developed due to the non-contact, fast response, high sensitivity, real-time and multi-elemental detection features. The development and applications of LIBS technique in Asia are summarized and discussed in this review paper. The researchers in Asia work on different aspects of the LIBS study in fundamentals, data processing and modeling, applications and instrumentations. According to the current research status, the challenges, opportunities and further development of LIBS technique in Asia are also evaluated to promote LIBS research and its applications.

  17. Laser-Induced Breakdown Spectroscopy: Capabilities and Applications

    Science.gov (United States)

    2010-07-01

    sample preparation. 14 6. References 1. Cremers D.A.; Radziemski, L. J. Handbook of Laser-Induced Breakdown Spectroscopy; West Sussex, England...30 (21), 2882–2884. 17. Salle, B.; Lacour, J. L.; Vors, E.; Fichet, P.; Maurice, S.; Cremers , D. A.; et al. Laser- Induced Breakdown Spectroscopy...90. Martin , M. Z.; Labbe, N.; Andre, N.; Harris, R.; Ebinger, M.; Wullschleger, S. D.; et al. High Resolution Applications of Laser-Induced

  18. Laser-induced torques in metallic ferromagnets

    Science.gov (United States)

    Freimuth, Frank; Blügel, Stefan; Mokrousov, Yuriy

    2016-10-01

    We study laser-induced torques in bcc Fe, hcp Co, and L 10 FePt based on first-principles electronic structure calculations and the Keldysh nonequilibrium formalism. We find that the torques have two contributions, one from the inverse Faraday effect (IFE) and one from the optical spin-transfer torque (OSTT). Depending on the ferromagnet at hand and on the quasiparticle broadening the two contributions may be of similar magnitude, or one contribution may dominate over the other. Additionally, we determine the nonequilibrium spin polarization in order to investigate its relation to the torque. We find the torques and the perpendicular component of the nonequilibrium spin polarization to be odd in the helicity of the laser light, while the spin polarization that is induced parallel to the magnetization is helicity independent. The parallel component of the nonequilibrium spin polarization is orders of magnitude larger than the perpendicular component. In the case of hcp Co we find good agreement between the calculated laser-induced torque and a recent experiment.

  19. Laser induced phase locking of hydrogen plasma striations

    Energy Technology Data Exchange (ETDEWEB)

    Glab, W.; Nayfeh, M.H.

    1982-04-01

    Laser induced transient striations of a hydrogen discharge plasma are studied as a function of the ''detuning'' of the discharge parameters from the steady-state oscillatory response conditions. We observed laser induced phase locking of the steady-state striations.

  20. Laser Induced Selective Activation For Subsequent Autocatalytic Electroless Plating

    DEFF Research Database (Denmark)

    Zhang, Yang

    The subject of this PhD thesis is “Laser induced selective activation for subsequent autocatalytic electroless plating.” The objective of the project is to investigate the process chains for micro structuring of polymer surfaces for selective micro metallization. Laser induced selective activation...

  1. Laser-induced fluorescence imaging of bacteria

    Science.gov (United States)

    Hilton, Peter J.

    1998-12-01

    This paper outlines a method for optically detecting bacteria on various backgrounds, such as meat, by imaging their laser induced auto-fluorescence response. This method can potentially operate in real-time, which is many times faster than current bacterial detection methods, which require culturing of bacterial samples. This paper describes the imaging technique employed whereby a laser spot is scanned across an object while capturing, filtering, and digitizing the returned light. Preliminary results of the bacterial auto-fluorescence are reported and plans for future research are discussed. The results to date are encouraging with six of the eight bacterial strains investigated exhibiting auto-fluorescence when excited at 488 nm. Discrimination of these bacterial strains against red meat is shown and techniques for reducing background fluorescence discussed.

  2. Laser induced fluorescence of dental caries

    Science.gov (United States)

    Albin, S.; Byvik, C. E.; Buoncristiani, A. M.

    1988-01-01

    Significant differences between the optical spectra taken from sound regions of teeth and carious regions have been observed. These differences appear both in absorption and in laser induced fluorescence spectra. Excitation by the 488 nm line of an argon ion laser beam showed a peak in the emission intensity around 553 nm for the sound dental material while the emission peak from the carious region was red-shifted by approximately 40 nm. The relative absorption of carious region was significantly higher at 488 nm; however its fluorescence intensity peak was lower by an order of magnitude compared to the sound tooth. Implications of these results for a safe, reliable and early detection of dental caries are discussed.

  3. Laser induced fluorescence of dental caries

    Science.gov (United States)

    Albin, S.; Byvik, C. E.; Buoncristiani, A. M.

    1988-01-01

    Significant differences between the optical spectra taken from sound regions of teeth and carious regions have been observed. These differences appear both in absorption and in laser induced fluorescence spectra. Excitation by the 488 nm line of an argon ion laser beam showed a peak in the emission intensity around 553 nm for the sound dental material while the emission peak from the carious region was red-shifted by approximately 40 nm. The relative absorption of carious region was significantly higher at 488 nm; however its fluorescence intensity peak was lower by an order of magnitude compared to the sound tooth. Implications of these results for a safe, reliable and early detection of dental caries are discussed.

  4. Laser induced single spot oxidation of titanium

    Energy Technology Data Exchange (ETDEWEB)

    Jwad, Tahseen, E-mail: taj355@bham.ac.uk; Deng, Sunan; Butt, Haider; Dimov, S.

    2016-11-30

    Highlights: • A new high resolution laser induced oxidation (colouring) method is proposed (single spot oxidation). • The method is applied to control oxide films thicknesses and hence colours on titanium substrates in micro-scale. • The method enable imprinting high resolution coloured image on Ti substrate. • Optical and morphological periodic surface structures are also produced by an array of oxide spots using the proposed method. • Colour coding of two colours into one field is presented. - Abstract: Titanium oxides have a wide range of applications in industry, and they can be formed on pure titanium using different methods. Laser-induced oxidation is one of the most reliable methods due to its controllability and selectivity. Colour marking is one of the main applications of the oxidation process. However, the colourizing process based on laser scanning strategies is limited by the relative large processing area in comparison to the beam size. Single spot oxidation of titanium substrates is proposed in this research in order to increase the resolution of the processed area and also to address the requirements of potential new applications. The method is applied to produce oxide films with different thicknesses and hence colours on titanium substrates. High resolution colour image is imprinted on a sheet of pure titanium by converting its pixels’ colours into laser parameter settings. Optical and morphological periodic surface structures are also produced by an array of oxide spots and then analysed. Two colours have been coded into one field and the dependencies of the reflected colours on incident and azimuthal angles of the light are discussed. The findings are of interest to a range of application areas, as they can be used to imprint optical devices such as diffusers and Fresnel lenses on metallic surfaces as well as for colour marking.

  5. 锪窝填充孔孔边角裂纹应力强度因子的有限元分析%Stress Intensity Factor Finite Element Analysis of Corner Crack at Rivet-filled Countersink Hole

    Institute of Scientific and Technical Information of China (English)

    屠少威; 黄其青; 郭今; 谢伟

    2012-01-01

    对锪窝填充孔孔边角裂纹应力强度因子进行研究对提高结构安全性具有重要意义。根据飞机上常用的锪窝铆接典型结构,运用ANSYS软件对锪窝孔孔边角裂纹进行有限元分析,建立铆钉与锪窝孔接触模拟铆钉对锪窝孔的填充作用。计算得到含铆钉填充以及空孔时锪窝孔边不同裂纹尺寸下裂纹前缘的应力强度因子分布。对比分析结果表明:铆钉填充能显著降低锪窝孔边角裂纹的应力强度因子,提高结构寿命。%Reseach of stress intensity factor on corner crack at rivet-filled countersink hole is of important significance for improving the safety of structure. Countersunk riveted joints are commonly used in aircraft structures and are the principle structures sensitive to fatigue cracking. Corner cracks initiated from both sides of a rivetfilled countersunk hole and an open hole with no riveting were analyzed using ANSYS, a finite element analysis package, to obtain the stress intensity factors (SIFs) along the crack fronts. The results indicate that the river filled process can significantly reduce the SIF of the corner cracks of countersunk holes and thus enhance the fa tigue resistance.

  6. Laser-Induced Incandescence in Microgravity

    Science.gov (United States)

    VanderWal, Randy L.

    1997-01-01

    Knowledge of soot concentration is important due to its presence and impact upon a wide range of combustion processes ranging from diffusion to premixed flames, laminar to turbulent processes and homogeneous to heterogeneous combustion. Measurement of soot volume fraction (f(sub v)) is essential to discerning its formation and growth. The presence of soot also affects other physical and chemical properties of combustion thereby affecting studies not directly concerned with either its formation or growth, such as radiative heat transfer, CO oxidation and fuel vaporization or pyrolysis rates. Microgravity offers unique opportunities for studying both soot growth and the effect of soot radiation upon flame structure and spread. Spatial scales and residence time scales are greatly extended in 0-g facilitating soot growth studies. With the varied geometries, short duration microgravity test times and time-varying processes there is a demand for measurement of f(sub v) with high spatial and temporal resolution. Laser-induced incandescence (LII) has advanced f(sub v) measurements in many 1-g combustion processes. To create laser-induced incandescence, a pulsed high intensity laser heats soot to incandescence temperatures. Using appropriate spectral and temporal detection conditions, the resulting incandescence can be selectively detected apart from the non-laser-heated soot and flame gases. Theoretical modelling and experiments have shown that the resulting incandescence is representative of f(sub v). Using an intensified array camera and a laser sheet for excitation, one- and two-dimensionally resolved LII images of f(sub v) have been obtained in 1-g. LII has been characterized and developed at NASA-Lewis for soot volume fraction determination in a wide range of 1-g combustion applications. Broadly grouped, the characterization work has included studies of excitation intensity, excitation wavelength and the optimum temporal and spectral detection conditions to enable an

  7. Suppression of superconductivity in the (La 2.5- xGd 0.5+ x)CaBa 3- xSr x(Cu 1- yIn y) 7O z system due to hole filling by In and its revival by hole doping with Ca

    Science.gov (United States)

    Vij, Reeta; Kundaliya, Darshan C.; Joshi, Amish G.; Kuberkar, Deelip G.; Kulkarni, Ramchandra G.

    2002-07-01

    The structural and superconducting properties of single phase (La 2.5- xGd 0.5+ x)CaBa 3- xSr x(Cu 1- yIn y) 7O z (LGCBSCuIn) with 0⩽ x⩽1 and 0⩽ y⩽0.1 as well as Ca-substituted (La 1.5- x‧Ca x‧Gd 1.5)CaBa 2Sr(Cu 0.90In 0.10)O z (LCGCBSCuIn) with 0⩽ x‧⩽0.6 compounds having triple-perovskite structure are investigated using X-ray diffraction, oxygen content, electrical resistivity and d.c. magnetization measurements. The effect of increasing simultaneous substitutions of Gd, Sr and In in LGCBSCuIn is to lower the carrier concentration and decrease Tc to zero at x=1 and y=0.1, which is attributed to hole filling by In. This suppression in Tc has been compensated for by appropriate hole doping with Ca, for instance in the oxide LCGCBSCuIn, the Tc increases from 0 K ( x‧=0) to 68 K ( x‧=0.6) due to the balance between the hole filling by In and hole doping by Ca.

  8. Laser-induced lipolysis on adipose cells

    Science.gov (United States)

    Solarte, Efrain; Gutierrez, O.; Neira, Rodrigo; Arroyave, J.; Isaza, Carolina; Ramirez, Hugo; Rebolledo, Aldo F.; Criollo, Willian; Ortiz, C.

    2004-10-01

    Recently, a new liposuction technique, using a low-level laser (LLL) device and Ultrawet solution prior to the procedure, demonstrated the movement of fat from the inside to the outside of the adipocyte (Neira et al., 2002). To determine the mechanisms involved, we have performed Scanning and Transmission Electron Microscopy studies; Light transmittance measurements on adipocyte dilutions; and a study of laser light propagation in adipose tissue. This studies show: 1. Cellular membrane alterations. 2. LLL is capable to reach the deep adipose tissue layer, and 3. The tumescence solution enhances the light propagation by clearing the tissue. MRI studies demonstrated the appearance of fat on laser treated abdominal tissue. Besides, adipocytes were cultivated and irradiated to observe the effects on isolated cells. These last studies show: 1. 635 nm-laser alone is capable of mobilizing cholesterol from the cell membrane; this action is enhanced by the presence of adrenaline and lidocaine. 2. Intracellular fat is released from adipocytes by co joint action of adrenaline, aminophyline and 635 nm-laser. Results are consistent with a laser induced cellular process, which causes fat release from the adipocytes into the intercellular space, besides the modification of the cellular membranes.

  9. Medical Applications of Laser Induced Breakdown Spectroscopy

    Science.gov (United States)

    Pathak, A. K.; Rai, N. K.; Singh, Ankita; Rai, A. K.; Rai, Pradeep K.; Rai, Pramod K.

    2014-11-01

    Sedentary lifestyle of human beings has resulted in various diseases and in turn we require a potential tool that can be used to address various issues related to human health. Laser Induced Breakdown Spectroscopy (LIBS) is one such potential optical analytical tool that has become quite popular because of its distinctive features that include applicability to any type/phase of samples with almost no sample preparation. Several reports are available that discusses the capabilities of LIBS, suitable for various applications in different branches of science which cannot be addressed by traditional analytical methods but only few reports are available for the medical applications of LIBS. In the present work, LIBS has been implemented to understand the role of various elements in the formation of gallstones (formed under the empyema and mucocele state of gallbladder) samples along with patient history that were collected from Purvancal region of Uttar Pradesh, India. The occurrence statistics of gallstones under the present study reveal higher occurrence of gallstones in female patients. The gallstone occurrence was found more prevalent for those male patients who were having the habit of either tobacco chewing, smoking or drinking alcohols. This work further reports in-situ LIBS study of deciduous tooth and in-vivo LIBS study of human nail.

  10. DNA deposition through laser induced forward transfer.

    Science.gov (United States)

    Colina, M; Serra, P; Fernández-Pradas, J M; Sevilla, L; Morenza, J L

    2005-02-15

    Laser induced forward transfer (LIFT) is a laser direct write technique that appears to be specially adequate for the production of biosensors, since it permits to deposit patterns of biomolecules with high spatial resolution. In the LIFT technique, a laser pulse is focused on a thin film of the material to be transferred through a transparent support, and under the action of the laser pulse, a small fraction of the film is transferred to a receptor substrate that is placed parallel to the film-support system. In the case of biomolecules transfer, the thin film consists in a liquid solution containing the biomolecules. In this work, microarrays of two different cDNAs have been both spotted by LIFT and pin microspotting onto a poly-L-lysine treated glass slide. Once transferred, all the microarrays have been submitted to hybridization with the complementary strands of the spotted cDNAs, each one tagged with a different fluorochrome. Comparative fluorescence scanner analyses have revealed that the microarrays transferred through LIFT are equivalent to those transferred through pin microspotting in terms of signal intensity and gene discrimination capacity, and that the action of the laser pulse does not result in significant damage of the transferred DNA.

  11. Laser induced single spot oxidation of titanium

    Science.gov (United States)

    Jwad, Tahseen; Deng, Sunan; Butt, Haider; Dimov, S.

    2016-11-01

    Titanium oxides have a wide range of applications in industry, and they can be formed on pure titanium using different methods. Laser-induced oxidation is one of the most reliable methods due to its controllability and selectivity. Colour marking is one of the main applications of the oxidation process. However, the colourizing process based on laser scanning strategies is limited by the relative large processing area in comparison to the beam size. Single spot oxidation of titanium substrates is proposed in this research in order to increase the resolution of the processed area and also to address the requirements of potential new applications. The method is applied to produce oxide films with different thicknesses and hence colours on titanium substrates. High resolution colour image is imprinted on a sheet of pure titanium by converting its pixels' colours into laser parameter settings. Optical and morphological periodic surface structures are also produced by an array of oxide spots and then analysed. Two colours have been coded into one field and the dependencies of the reflected colours on incident and azimuthal angles of the light are discussed. The findings are of interest to a range of application areas, as they can be used to imprint optical devices such as diffusers and Fresnel lenses on metallic surfaces as well as for colour marking.

  12. Compact High Sensitive Laser-Induced Breakdown Spectroscopy Instrument Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Laser induced breakdown spectroscopy (LIBS) is a versatile tool for in situ substance characterization. Existing LIBS instruments are not compact enough for space...

  13. Pulsed laser-induced formation of silica nanogrids

    National Research Council Canada - National Science Library

    Ihlemann, Jürgen; Weichenhain-Schriever, Ruth

    2014-01-01

    ... ) coating through the transparent substrate. A polydimethylsiloxane (PDMS) superstrate (cover layer) coated on top of the SiO x film prior to laser exposure serves as confinement for controlled laser-induced structure formation...

  14. Fabricating micro embossments on the metal surface through spatially modulating laser-induced shock wave

    Science.gov (United States)

    Ye, Y. X.; Xuan, T.; Lian, Z. C.; Hua, X. J.; Fu, Y. H.

    2015-12-01

    In this paper, we propose one improved method to fabricate micro embossments on the metal surface through laser shock processing. One mapping layer with holes must be actively designed and produced on the metal surface, with which, laser-induced shock wave will be spatially modulated. Laser shock experiments were conducted. Then the surface morphologies, and metallographic microstructures were characterized. The forming process of the micro embossments was simulated with ABAQUS. The results show that under the spatially modulated shock loading, the surface material flows from the high-pressure zone to the low-pressure zone, which is responsible for forming the micro embossments. The shapes, sizes and arrangements of the micro embossments conform to those of the mapping holes. The hardnesses on the entire laser-shocked zones improve remarkably due to the plastic deformation at a high strain rate. The influences of the laser energy and mask pattern on the embossed structures are presented. Within certain limits, increasing laser energy is beneficial for making the embossment more convex. However, further excessively increasing the laser energy, the embossment will exhibit the height saturation due to the pressure rise within the closed mapping hole. The transverse sizes of the mapping holes also can influence the embossment heights significantly. Process parameters need to be chosen carefully to suppress the severe adiabatic compression of the gas within the mapping holes, and then avoid weakening the mechanical properties of the micro embossments. This method has a potential application in manufacturing protruded structures on the metal surface.

  15. Femtosecond laser-induced cavitations in the lens of the human eye

    DEFF Research Database (Denmark)

    Kessel, Line; Nymand, Jose; Harbst, Michael;

    2007-01-01

    Ultrafast femtosecond lasers are used increasingly for a wide range of medicai purposes. The immediate tissue response to pulses above a certain threshold is optically or laser induced breakdown, which is often visible as gas-filled cavities that persist for some time. In the present study, we at...... laser effects in the len s that have a potential for therapeutic application and treatment of eye dis ease though further studies are needed to shed light on the nature of the formation of delayed cavitations.......Ultrafast femtosecond lasers are used increasingly for a wide range of medicai purposes. The immediate tissue response to pulses above a certain threshold is optically or laser induced breakdown, which is often visible as gas-filled cavities that persist for some time. In the present study, we...... attempted to define the cavitation threshold in the human lens in vitro using multiphoton effects base d on radiation from a femtosecond 800 nm Ti:Sapphire laser. Cavitations were observed from pulse energy densities exceeding 16 mJ/cm2, but only after several minutes of exposure and not as a result...

  16. Femtosecond laser-induced cavitations in the lens of the human eye

    DEFF Research Database (Denmark)

    Kessel, Line; Nymand, Jose; Harbst, Michael;

    Ultrafast femtosecond lasers are used increasingly for a wide range of medicai purposes. The immediate tissue response to pulses above a certain threshold is optically or laser induced breakdown, which is often visible as gas-filled cavities that persist for some time. In the present study, we at...... laser effects in the len s that have a potential for therapeutic application and treatment of eye dis ease though further studies are needed to shed light on the nature of the formation of delayed cavitations.......Ultrafast femtosecond lasers are used increasingly for a wide range of medicai purposes. The immediate tissue response to pulses above a certain threshold is optically or laser induced breakdown, which is often visible as gas-filled cavities that persist for some time. In the present study, we...... attempted to define the cavitation threshold in the human lens in vitro using multiphoton effects base d on radiation from a femtosecond 800 nm Ti:Sapphire laser. Cavitations were observed from pulse energy densities exceeding 16 mJ/cm2, but only after several minutes of exposure and not as a result...

  17. Laser-Induced Incandescence: Excitation Intensity

    Science.gov (United States)

    Vander Wal, Randall L.; Jensen, Kirk A.

    1998-03-01

    Assumptions of theoretical laser-induced incandescence (LII) models along with possible effects of high-intensity laser light on soot aggregates and the constituent primary particles are discussed in relation to selection of excitation laser fluence. Ex situ visualization of laser-heated soot by use of transmission electron microscopy reveals significant morphological changes (graphitization) induced by pulsed laser heating. Pulsed laser transmission measurements within a premixed laminar sooting flame suggest that soot vaporization occurs for laser fluences greater than 0.5 J cm 2 at 1064 nm. Radial LII intensity profiles at different axial heights in a laminar ethylene gas jet diffusion flame reveal a wide range of signal levels depending on the laser fluence that is varied over an eight fold range. Results of double-pulse excitation experiments in which a second laser pulse heats in situ the same soot that was heated by a prior laser pulse are detailed. These two-pulse measurements suggest varying degrees of soot structural change for fluences below and above a vaporization threshold of 0.5 J cm 2 at 1064 nm. Normalization of the radial-resolved LII signals based on integrated intensities, however, yields self-similar profiles. The self-similarity suggests robustness of LII for accurate relative measurement of soot volume fraction despite the morphological changes induced in the soot, variations in soot aggregate and primary particle size, and local gas temperature. Comparison of LII intensity profiles with soot volume fractions ( f v ) derived by light extinction validates LII for quantitative determination of f v upon calibration for laser fluences ranging from 0.09 to 0.73 J cm 2 .

  18. Metal surface nitriding by laser induced plasma

    Science.gov (United States)

    Thomann, A. L.; Boulmer-Leborgne, C.; Andreazza-Vignolle, C.; Andreazza, P.; Hermann, J.; Blondiaux, G.

    1996-10-01

    We study a nitriding technique of metals by means of laser induced plasma. The synthesized layers are composed of a nitrogen concentration gradient over several μm depth, and are expected to be useful for tribological applications with no adhesion problem. The nitriding method is tested on the synthesis of titanium nitride which is a well-known compound, obtained at present by many deposition and diffusion techniques. In the method of interest, a laser beam is focused on a titanium target in a nitrogen atmosphere, leading to the creation of a plasma over the metal surface. In order to understand the layer formation, it is necessary to characterize the plasma as well as the surface that it has been in contact with. Progressive nitrogen incorporation in the titanium lattice and TiN synthesis are studied by characterizing samples prepared with increasing laser shot number (100-4000). The role of the laser wavelength is also inspected by comparing layers obtained with two kinds of pulsed lasers: a transversal-excited-atmospheric-pressure-CO2 laser (λ=10.6 μm) and a XeCl excimer laser (λ=308 nm). Simulations of the target temperature rise under laser irradiation are performed, which evidence differences in the initial laser/material interaction (material heated thickness, heating time duration, etc.) depending on the laser features (wavelength and pulse time duration). Results from plasma characterization also point out that the plasma composition and propagation mode depend on the laser wavelength. Correlation of these results with those obtained from layer analyses shows at first the important role played by the plasma in the nitrogen incorporation. Its presence is necessary and allows N2 dissociation and a better energy coupling with the target. Second, it appears that the nitrogen diffusion governs the nitriding process. The study of the metal nitriding efficiency, depending on the laser used, allows us to explain the differences observed in the layer features

  19. Effect of native defects and laser-induced defects on multi-shot laser-induced damage in multilayer mirrors

    Institute of Scientific and Technical Information of China (English)

    Ying Wang; Yuanan Zhao; Tanda Shao; Zhengxiu Fan

    2011-01-01

    The roles of laser-induced defects and native defects in multilayer mirrors under multi-shot irradiation condition are investigated. The HfO2/SiO2 dielectric mirrors are deposited by electron beam evaporation (EBE). Laser damage testing is carried out on both the 1-on-l and S-on-1 regimes using 355-nm pulsed laser at a duration of 8 ns. It is found that the single-shot laser-induced damage threshold (LIDT) is much higher than the multi-shot LIDT. In the multi-shot mode, the main factor influencing LIDT is the accumulation of irreversible laser-induced defects and native defects. The surface morphologies of the samples are observed by optical microscopy. Moreover, the number of laser-induced defects affects the damage probability of the samples. A correlative model based on critical conduction band (CB) electron density (ED) is presented to simulate the multi-shot damage behavior.%@@ The roles of laser-induced defects and native defects in multilayer mirrors under multi-shot irradiation condition are investigated.The Hf02/SiO2 dielectric mirrors are deposited by electron beam evaporation (EBE).Laser damage testing is carried out on both the 1-on-1 and S-on-1 regimes using 355-nn pulsed laser at a duration of 8 us.It is found that the single-shot laser-induced damage threshold(LIDT)is much higher than the multi-shot LIDT.In the multi-shot mode,the main factor influencing LIDT is the accumulation of irreversible laser-induced defects and native defects.The surface morphologies of the samples are observed by optical microscopy.Moreover,the number of laser-induced defects affects the damage probability of the samples.A correlative model based on critical conduction band(CB)electron density(ED)is presented to simulate the multi-shot damage behavior.

  20. Laser Induced Damage in Optical Materials: 1980.

    Science.gov (United States)

    1981-10-01

    hypodermic needle . The cell has valves which permit purging or filling with gases other than air when necessary. The absolute absorption calibration of...Schmid The High Frequency Electron Scattering Rate and Drude Zener Theory in Compound Semiconductors...446 N. Judell, S.S. Mitra, A. Vaidyanathan and A.H. Guenther Theory of Nonlinear Beam Propagation in Optical Waveguides

  1. CONSTRUCTION TECHNOLOGY OF ROTARY DRILLING HOLE DRY IN BORED FILLING PILE%钻孔灌注桩旋挖干取土成孔施工技术

    Institute of Scientific and Technical Information of China (English)

    王玮

    2012-01-01

    According to the different strata and ground water level,construction of rotary drilling hole may using process with drilling pile dry and mud. Drilling pile dry without mud, hole wall do not produce sludge, thickness of waste in hole bottom is small,conducive to play the bearing capacity of pile. Meanwhile,high construction efficiency, mud - free emission,pollution of small,especially suitable for construction of urban construction foundation.%根据不同的地层及地下水位情况,旋挖钻成孔灌注桩可采用干取土成孔和泥浆护壁成孔工艺。干取土成孔工艺不需泥浆护壁,孔壁不产生泥皮,孔底渣土厚度小,利于桩基承载力的发挥。同时,施丁效率高,无泥浆排放,对环境污染小,尤其适合于城市建设基础的施工。

  2. Laser Induced Damage in Optical Materials: 1979.

    Science.gov (United States)

    1980-07-01

    electrical properties shows that the group of high-conductivity chalco - genides are typical electronic semiconductors with a hole conduction mechanism. The...with the long-range order and tne different role impurities play in a glass and in a crystal. Zone purification of chalco - genide leads to a strong...considered since it was assumed that anti-reflection coatings would be used in the actual switch. Furthermore, internal reflections at the support chalco

  3. Research on laser induced acoustic source based underwater communication system

    Science.gov (United States)

    Lei, Lihua; Zhou, Ju; Zhang, Lei; Wan, Xiaoyun

    2016-10-01

    Acoustic transducers are traditionally used to generate underwater acoustical energy with the device physically immersed in water. Novel methods are required for communicating from an in-air platform or surface vessel to a submerged vessel. One possible noncontact downlink communication system involves the use of laser induced acoustic source. The most common mechanisms of opto-acoustic energy conversion are, by order of increasing laser energy density and efficiency, thermal expansion, surface evaporation and optical breakdown. The laser induced acoustic source inherently bears the obvious advantage of not requiring any physical transducer in the medium. At the same time, acoustic energy propagation is efficient in water, whereas optical energy propagate well in air, leading to a more efficiency opto-acoustic communication method. In this paper, an opto-acoustic underwater Communication system is described, aiming to study and analysis whether laser induced sound could achieve good performance for effective communication in practical application.

  4. Surgical Treatment of Laser Induced Eye Injuries

    Science.gov (United States)

    1992-08-21

    le-ions t [etvThe animalls werte is’ointvi ttw .r , to) V; andIri etl"Ilta i in vin.\\ Icc’hxil ~. Was a cvntral arefa ’it rnlzIci’ hifrs after sulrge...phagocytic cells wete observed in the dense erythr’ - ~ ex-te laver and~ immedliatelY overlvii::Z ~ ~ the RI’E laver. In peripheral art .;L4 over mothle he...latYs after Ilu-rn- I art iallyý vascularized i retinal nmode-l photoreceiptir ý1111sv r-etinal degenefration (fill- orrhauit-. or have not investigatedI

  5. Ultrafast Molecular Imaging by Laser Induced Electron Diffraction

    CERN Document Server

    Peters, Michel; Cornaggia, Christian; Saugout, Sébastien; Charron, Eric; Keller, Arne; Atabek, Osman

    2010-01-01

    We address the feasibility of imaging geometric and orbital structure of a polyatomic molecule on an attosecond time-scale using the Laser Induced Electron Diffraction, LIED, technique [T. Zuo \\textit{et al.}, Chem. Phys. Lett. \\textbf{259}, 313 (1996)]. We present numerical results obtained for the CO$_2$ molecule using a single active electron model. The molecular geometry (bond-lengths) is determined within 3% of accuracy from a diffraction pattern which also reflects the nodal properties of the initial molecular orbital. Robustness of the structure determination is discussed with respect to vibrational and rotational motions with a complete interpretation of the laser-induced mechanisms.

  6. Absorption tomography of laser induced plasmas with a large aperture

    CERN Document Server

    Shabanov, Sergei V

    2010-01-01

    An emission tomography of laser-induced plasmas employed in the laser induced breakdown spectroscopy (LIBS) requires long signal integration times during which the plasma cannot be considered stationary. To reduce the integration time, it is proposed to measure a plasma absorption in parallel rays with an aperture that collects light coming from large fractions of the plasma plume at each aperture position. The needed spatial resolution is achieved by a special numerical data processing. Another advantage of the proposed procedure is that inexpensive linear CCD or non-discrete (PMT, photodiode) detectors can be used instead of costly 2-dimensional detectors.

  7. Propane decomposition and conversion into other hydrocarbons using metal target assisted laser induced plasma

    Science.gov (United States)

    Moosakhani, A.; Parvin, P.; Reyhani, A.; Mortazavi, S. Z.

    2017-01-01

    It is shown that the propane molecules are strongly decomposed in the metal assisted laser induced plasma based on the nano-catalytic adsorption. A Q-Switched Nd:YAG laser is employed to irradiate the propane gas filled in the control chamber in the presence of the reactive metals such as Ni, Fe, Pd, and Cu in order to study the effect of catalysts during the decomposition. The catalytic targets simultaneously facilitate the plasma formation and the decomposition events leading to generate a wide distribution of the light and heavy hydrocarbon molecules, mainly due to the recombination processes. Fourier transform infrared spectroscopy and gas chromatography instruments support the findings by detecting the synthetic components. Furthermore, the optical emission spectroscopy of the laser induced plasma emissions realizes the real time monitoring of the reactions taking place during each laser shot. The subsequent recombination events give rise to the generation of a variety of the hydrocarbon molecules. The dissociation rate, conversion ratio, selectivity, and yield as well as the performance factor arise mainly from the catalytic effects of the metal species. Moreover, the ablation rate of the targets of interest is taken into account as a measure of the catalytic reactivity due to the abundance of the metal species ablated from the target. This leads to assess the better performance factor for Pd among four metal catalysts of interest during propane decomposition. Finally, the molecules such as ethane and ethylene are identified as the stable abundant species created during the successive molecular recombination processes.

  8. 某铁矿冻结孔的缓凝水泥浆固管充填技术%Study on the Filling Technology of Freezing Hole Using Retarding Cement Grout in an Iron Mine

    Institute of Scientific and Technical Information of China (English)

    王衍森; 杨福军; 冷阳光

    2012-01-01

    近年来,冻结法凿井技术在我国富水岩层矿井建设中的应用越来越广泛.为防止冻结壁融化后冻结孔成为竖向导水通道,威胁矿井的安全,冻结孔必须开展固管充填处理.针对某铁矿回风井冻结法凿井面临的地层条件及钻孔泥浆特点,通过室内及现场试验研究,获得了具有良好稳定性、较长缓凝时间且能与钻孔化学泥浆相容的缓凝水泥浆液配方,并研究制订了合理的冻结孔固管充填施工技术与工艺.冻结孔固管充填技术在该矿井的成功应用,证实了所研发的缓凝水泥浆液配方及相关施工技术与工艺的可行性与可靠性.%In recent years, freezing sinking technology is widely used in water-bearing rock strata in our country. To prevent the freezing hole becoming vertical water channels after the ice wall thawing, consequently threatening the safety of the mine,the hollow space around freezing pipes in freezing holes must be filled. Aiming at the strara condition and drilling mud features in freeze sinking in the ventilation shaft of an iron mine, the retarding cement grout formula, which is stable and has long slow setting time and considerable compatibility with drilling mud,was obtained through a large number of laboratory and field tests; then,the reasonable technology and process were produced for the freezing holes filling. The successful application of this technology in the iron mine, proved its feasibility and reliability of the formula and the related process.

  9. Measurement of gas flow velocities by laser-induced gratings

    Energy Technology Data Exchange (ETDEWEB)

    Hemmerling, B.; Stampanoni-Panariello, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Kozlov, A.D.N. [General Physics Institute, Moscow (Russian Federation)

    1999-08-01

    Time resolved light scattering from laser-induced electrostrictive gratings was used for the determination of flow velocities in air at room temperature. By measuring the velocity profile across the width of a slit nozzle we demonstrated the high spatial resolution (about 200 mm) of this novel technique. (author) 3 figs., 1 ref.

  10. Laser-Induced Breakdown Spectroscopy and Chlorophyll a Flourescence Transients

    DEFF Research Database (Denmark)

    Frydenvang, Jens

    of a sufficient quality; something that remains a problem for many in-situ methods. In my PhD, I present my work with two such in-situ methods, Laser-Induced Breakdown Spectroscopy (LIBS) and OJIP transients, the rising part of chlorophyll a fluorescence transients from dark-adapted leaves....

  11. Laser-induced fluorescence of oral mucosa cancer

    Science.gov (United States)

    Jaliashvili, Z. V.; Medoidze, T. D.; Melikishvili, Z. G.; Gogilashvili, K. T.

    2017-10-01

    The laser-induced fluorescence (LIF) spectra have been measured for cancer-infused and control mice mucosa tissues. It was established that there is quite a difference between their LIF spectral shapes. These spectral shapes are used to express the diagnostic of different states of tissues: from normal to cancer.

  12. Gas permeation and temperature effects in laser-induced delamination

    NARCIS (Netherlands)

    Fedorov, Alexander; Vellinga, Willem-Pier; De Hosson, Jeff

    Laser-induced delamination (LID) is a technique aimed at measuring the work of adhesion of thin polymer coatings on metal substrates. A laser Pulse is used to create a blister that initiates delamination of the film under pressure. The stress fields in the blister wall and the work of adhesion of

  13. Adhesion of polymer coatings studied by laser-induced delamination

    NARCIS (Netherlands)

    Fedorov, A; De Hosson, JTM

    2005-01-01

    This paper concentrates on the laser-induced delamination technique, aimed at measuring the practical work of adhesion of thin polymer coatings on metal substrates. In this technique an infrared laser-pulsed beam is used to create an initial blister. Upon increasing the pulse intensity, the size of

  14. Laser-Induced Breakdown Spectroscopy and Chlorophyll a Flourescence Transients

    DEFF Research Database (Denmark)

    Frydenvang, Jens

    of a sufficient quality; something that remains a problem for many in-situ methods. In my PhD, I present my work with two such in-situ methods, Laser-Induced Breakdown Spectroscopy (LIBS) and OJIP transients, the rising part of chlorophyll a fluorescence transients from dark-adapted leaves....

  15. Laser-Induced Rotation of Iodine Molecules in Helium Nanodroplets

    DEFF Research Database (Denmark)

    Shepperson, Benjamin; Sondergaard, Anders A.; Christiansen, Lars

    2017-01-01

    Rotation of molecules embedded in helium nanodroplets is explored by a combination of fs laser-induced alignment experiments and angulon quasiparticle theory. We demonstrate that at low fluence of the fs alignment pulse, the molecule and its solvation shell can be set into coherent collective...... its helium shell. Our results open novel opportunities for studying nonequilibrium solute-solvent dynamics and quantum thermalization....

  16. Laser-induced incandescence : recent trends and current questions

    NARCIS (Netherlands)

    Schulz, C.; Kock, B.F.; Hofmann, M.; Michelsen, H.; Will, S.; Bougie, B.; Suntz, R.; Smallwood, G.

    2006-01-01

    This paper provides an overview of a workshop focused on fundamental experimental and theoretical aspects of soot measurements by laser-induced incandescence (LII). This workshop was held in Duisburg, Germany in September 2005. The goal of the workshop was to review the current understanding of the

  17. Laser-Induced Breakdown Spectroscopy of Trace Metals

    Science.gov (United States)

    Simons, Stephen (Technical Monitor); VanderWal, Randall L.; Ticich, Thomas M.; West, Joseph R., Jr.

    2004-01-01

    An alternative approach for laser-induced breakdown spectroscopy (LIBS) determination of trace metal determination in liquids is demonstrated. The limits of detection (LOD) for the technique ranged from 10 ppb to 10 ppm for 15 metals metals (Mg, Al, Si, Ca, Ti, Cr, Fe, Co, Ni, Cu, Zn, As, Cd, Hg, Pb) tested.

  18. Laser-induced incandescence : recent trends and current questions

    NARCIS (Netherlands)

    Schulz, C.; Kock, B.F.; Hofmann, M.; Michelsen, H.; Will, S.; Bougie, B.; Suntz, R.; Smallwood, G.

    2006-01-01

    This paper provides an overview of a workshop focused on fundamental experimental and theoretical aspects of soot measurements by laser-induced incandescence (LII). This workshop was held in Duisburg, Germany in September 2005. The goal of the workshop was to review the current understanding of the

  19. Additive interconnect fabrication by picosecond Laser Induced Forward Transfer

    NARCIS (Netherlands)

    Oosterhuis, G.; Veld, B.H. in 't; Ebberink, G.; Del Cerro, D.A.; Eijnden, E. van den; Chall, P.; Zon, B. van der

    2010-01-01

    Laser Induced Forward Transfer (LIFT) is a single step, dry deposition process which shows great potential for interconnect fabrication. TNO, in cooperation with ALSI and University of Twente have studied the feature size and resistivity of copper structures deposited using picosecond (ps) LIFT. Sma

  20. Additive interconnect fabrication by picosecond Laser Induced Forward Transfer

    NARCIS (Netherlands)

    Oosterhuis, G.; Veld, B.H. in 't; Ebberink, G.; Del Cerro, D.A.; Eijnden, E. van den; Chall, P.; Zon, B. van der

    2010-01-01

    Laser Induced Forward Transfer (LIFT) is a single step, dry deposition process which shows great potential for interconnect fabrication. TNO, in cooperation with ALSI and University of Twente have studied the feature size and resistivity of copper structures deposited using picosecond (ps) LIFT. Sma

  1. Laser-induced collisional autoionization in europium and strontium atoms.

    Science.gov (United States)

    Buffa, R

    1995-01-15

    An experiment that involves laser-induced collisional autoionization in europium and strontium atoms is proposed and the spectral line shape of the cross section is calculated on the basis of data available in the literature. The feasibility of the experiment both in oven cells and in a crossed-atomic-beam geometry is discussed.

  2. Towards Friction Control using laser-induced periodic Surface Structures

    NARCIS (Netherlands)

    Eichstädt, J.; Römer, G.R.B.E.; Huis in 't Veld, A.J.

    2011-01-01

    This paper aims at contributing to the study of laser-induced periodic surface structures (LIPSS) and the description of their tribological properties in order to facilitate the knowledge for contact mechanical applications. To obtain laser parameters for LIPSS formation, we propose to execute two D

  3. A comparative study of laser-induced demagnetization dynamics in Fe, Co, and Ni

    Science.gov (United States)

    Gopalakrishnan, Maithreyi; Gentry, Christian; Zusin, Dmitriy; Grychtol, Patrik; Knut, Ronny; Shaw, Justin; Nembach, Hans; Mathias, Stefan; Aeschlimann, Martin; Oppeneer, Peter; Schneider, Claus; Kapteyn, Henry; Murnane, Margaret

    Even twenty years after the discovery of ultrafast demagnetization of ferromagnetic materials induced by a femtosecond laser pulse there is still an ongoing debate about the mechanisms that drive the process. Surprisingly, a comprehensive study that compares demagnetization dynamics in different materials on equal footing is lacking. Yet, the scientific community would greatly benefit from such study. We fill this gap by performing a systematic comparison of ultrafast demagnetization behavior in Iron, Cobalt and Nickel, the simplest itinerant ferromagnets, under a wide range of pump fluences. In this experiment, we utilize a tabletop broadband extreme ultraviolet source to probe magnetization dynamics at the M2,3 absorption edges of these three elements using the transverse magneto-optical Kerr effect. The obtained data can be used to inform theory and, thereby, assist in resolving the remaining questions about the micro- and macroscopic mechanisms behind ultrafast laser-induced magnetization dynamics in materials.

  4. Laser induced breakdown detection for the assessment of colloid mediated radionuclide migration

    CERN Document Server

    Walther, C; Hauser, W; Kim, J I; Scherbaum, F J

    2002-01-01

    Colloids play an important role in the transport of pollutants in the environment. Harmful substances can undergo transport over large distances if bound to colloids in aqueous surrounding. One important example is the migration of Pu(IV) at unexpectedly high rates over several miles at a Nevada nuclear detonation test site. For long term safety assessments of radioactive waste repositories, it is hence crucial to know about the amount, size distribution and chemical composition of colloids in the ground water. Standard methods (e.g. light scattering) can be applied for high concentrations and large sizes of particles. Colloids smaller than 50 nm, however, are detected with very low efficiency. Laser induced breakdown detection (LIBD) can fill this gap. A new instrumentation is presented, which as compared to previous instruments, opens up a much wider operational dynamic range, now covering three orders of magnitude in size (5-1000 nm) and seven orders of magnitude in particle concentration (1 ppt - several ...

  5. Low-reflectance laser-induced surface nanostructures created with a picosecond laser

    Science.gov (United States)

    Sarbada, Shashank; Huang, Zhifeng; Shin, Yung C.; Ruan, Xiulin

    2016-04-01

    Using high-speed picosecond laser pulse irradiation, low-reflectance laser-induced periodic surface structures (LIPSS) have been created on polycrystalline silicon. The effects of laser fluence, scan speed, overlapping ratio and polarization angle on the formation of LIPSS are reported. The anti-reflective properties of periodic structures are discussed, and the ideal LIPSS for low surface reflectance is presented. A decrease of 35.7 % in average reflectance of the silicon wafer was achieved over the wavelength range of 400-860 nm when it was textured with LIPSS at high scan speeds of 4000 mm/s. Experimental results of broadband reflectance of silicon wafers textured with LIPSS have been compared with finite difference time domain simulations and are in good agreement, showing high predictability in reflectance values for different structures. The effects of changing the LIPSS profile, fill factor and valley depth on the surface reflectance were also analyzed through simulations.

  6. Filling the holes in the CaFe4As3 structure: Synthesis and magnetism of CaCo5As3

    Science.gov (United States)

    Rosa, P. F. S.; Scott, B. L.; Ronning, F.; Bauer, E. D.; Thompson, J. D.

    2017-07-01

    Here, we investigate single crystals of CaCo5As3 by means of single-crystal x-ray diffraction, microprobe, magnetic susceptibility, heat capacity, and pressure-dependent transport measurements. CaCo5As3 shares the same structure of CaFe4As3 with an additional Co atom filling a lattice vacancy and undergoes a magnetic transition at TM=16 K associated with a frustrated magnetic order. CaCo5As3 displays metallic behavior and its Sommerfeld coefficient (γ =70 mJ/mol K2) indicates a moderate enhancement of electron-electron correlations. Transport data under pressures to 2.5 GPa reveal a suppression of TM at a rate of -0.008 K/GPa. First-principles electronic structure calculations show a complex three-dimensional band structure and magnetic moments that depend on the local environment at each Co site. Our results are compared with previous data on CaFe4As3 and provide a scenario for a magnetically frustrated ground state in this family of compounds.

  7. Femtosecond-laser induced dynamics of CO on Ru(0001): Deep insights from a hot-electron friction model including surface motion

    Science.gov (United States)

    Scholz, Robert; Floß, Gereon; Saalfrank, Peter; Füchsel, Gernot; Lončarić, Ivor; Juaristi, J. I.

    2016-10-01

    A Langevin model accounting for all six molecular degrees of freedom is applied to femtosecond-laser induced, hot-electron driven dynamics of Ru(0001)(2 ×2 ):CO. In our molecular dynamics with electronic friction approach, a recently developed potential energy surface based on gradient-corrected density functional theory accounting for van der Waals interactions is adopted. Electronic friction due to the coupling of molecular degrees of freedom to electron-hole pairs in the metal are included via a local density friction approximation, and surface phonons by a generalized Langevin oscillator model. The action of ultrashort laser pulses enters through a substrate-mediated, hot-electron mechanism via a time-dependent electronic temperature (derived from a two-temperature model), causing random forces acting on the molecule. The model is applied to laser induced lateral diffusion of CO on the surface, "hot adsorbate" formation, and laser induced desorption. Reaction probabilities are strongly enhanced compared to purely thermal processes, both for diffusion and desorption. Reaction yields depend in a characteristic (nonlinear) fashion on the applied laser fluence, as well as branching ratios for various reaction channels. Computed two-pulse correlation traces for desorption and other indicators suggest that aside from electron-hole pairs, phonons play a non-negligible role for laser induced dynamics in this system, acting on a surprisingly short time scale. Our simulations on precomputed potentials allow for good statistics and the treatment of long-time dynamics (300 ps), giving insight into this system which hitherto has not been reached. We find generally good agreement with experimental data where available and make predictions in addition. A recently proposed laser induced population of physisorbed precursor states could not be observed with the present low-coverage model.

  8. 利用电镀铜填充微米盲孔与通孔之应用%Applications of Microvia and Through-Hole Filling by Copper Electroplating

    Institute of Scientific and Technical Information of China (English)

    窦维平

    2012-01-01

    电子产品之高密度内连结制程技术,从上游的半导体制程到中游的封装基板制程,一直到下游的电路板制程,似乎都需要依赖电镀铜填孔技术.近几年来,电镀铜填孔技术日趋受到重视,相关专秘的电镀配方、技术、设备以及周边配套的仪器设施等,如雨后春笋般地发展起来.以往常用但未能深入了解的电镀铜技术有了跃进式的突破,值得探讨.这些技术的发展,似乎有着轮回应用的走势,即下游电路板的电镀铜制程技术似乎渐渐朝半导体制程技术发展,因此衍生出电镀铜填充盲孔的制程技术;而上游的半导体制程工艺中以往没有所谓的镀通孔(PTH),如今却因为3D芯片整合的需要,出现了所谓的穿硅孔(TSV),而所谓的TSV,其实与镀通孔具有类似的制程步骤以及相同的功能与目的,只是介电材料、设备等不同而已.针对目前电镀铜填充微米级盲孔与通孔的相关技术作概略式的介绍与回顾.%The interconnect process technology of electronic products, from the upstream semiconductor process to the midstream packaging process and to the downstream printed circuit board (PCB) process, greatly need copper filling technology by electroplating. Therefore, copper filling by electroplating is being taken much attention. The related confidential formulas, technologies, tools and corresponding instruments are being developed as bamboo shoots after a spring rain. Hence, the copper electroplating technology, which is often used but not understood well, has been greatly improved and explored. Interestingly, the copper metallization technology has a trend that rotates between two industry fields, that is, the development of copper electroplating in downstream PCB gradually approaches to that of semiconductor. Therefore, microvia filling by copper electroplating emerges in PCB. On the other hand, the upstream semiconductor process had no plated through hole

  9. Applications of laser-induced gratings to spectroscopy and dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Rohlfing, E.A. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    This program has traditionally emphasized two principal areas of research. The first is the spectroscopic characterization of large-amplitude motion on the ground-state potential surface of small, transient molecules. The second is the reactivity of carbonaceous clusters and its relevance to soot and fullerene formation in combustion. Motivated initially by the desire to find improved methods of obtaining stimulated emission pumping (SEP) spectra of transients, most of our recent work has centered on the use of laser-induced gratings or resonant four-wave mixing in free-jet expansions. These techniques show great promise for several chemical applications, including molecular spectroscopy and photodissociation dynamics. The author describes recent applications of two-color laser-induced grating spectroscopy (LIGS) to obtain background-free SEP spectra of transients and double resonance spectra of nonfluorescing species, and the use of photofragment transient gratings to probe photodissociation dynamics.

  10. Laser Induced Fluorescence Spectroscopy of IrN

    Institute of Scientific and Technical Information of China (English)

    H. F. Pang; A. S. C. Cheung

    2009-01-01

    High resolution laser induced fluorescence spectra of IrN in the spectral region between 394and 520 nm were recorded using laser vaporization/reaction free jet expansion and laser induced fluorescence spectroscopy. Seven new vibronic transition bands were observed and analyzed. TwoΩ=1 and five Ω=0 new states were identified. Least squares fit of rotationally resolved transition lines yielded accurate molecular constants for the upper states. Spectra of isotopic molecules were observed, which provided confirmation for the vibrational assignment. Comparison of the observed electronic states of IrB, IrC, and IrN provides a good understanding of the chemical bonding of this group of molecules.

  11. Supersonic laser-induced jetting of aluminum micro-droplets

    Energy Technology Data Exchange (ETDEWEB)

    Zenou, M. [Racah Institute of Physics and the Harvey M. Kruger Family Center for Nano-science and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Additive Manufacturing Lab, Orbotech Ltd., P.O. Box 215, 81101 Yavne (Israel); Sa' ar, A. [Racah Institute of Physics and the Harvey M. Kruger Family Center for Nano-science and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Kotler, Z. [Additive Manufacturing Lab, Orbotech Ltd., P.O. Box 215, 81101 Yavne (Israel)

    2015-05-04

    The droplet velocity and the incubation time of pure aluminum micro-droplets, printed using the method of sub-nanosecond laser induced forward transfer, have been measured indicating the formation of supersonic laser-induced jetting. The incubation time and the droplet velocity were extracted by measuring a transient electrical signal associated with droplet landing on the surface of the acceptor substrate. This technique has been exploited for studying small volume droplets, in the range of 10–100 femto-litters for which supersonic velocities were measured. The results suggest elastic propagation of the droplets across the donor-to-acceptor gap, a nonlinear deposition dynamics on the surface of the acceptor and overall efficient energy transfer from the laser beam to the droplets.

  12. Compositional Analysis of Drugs by Laser-Induced Breakdown Spectroscopy

    Science.gov (United States)

    Beldjilali, S. A.; Axente, E.; Belasri, A.; Baba-Hamed, T.; Hermann, J.

    2017-07-01

    The feasibility of the compositional analysis of drugs by calibration-free laser-induced breakdown spectroscopy (LIBS) was investigated using multivitamin tablets as a sample material. The plasma was produced by a frequencyquadrupled Nd:YAG laser delivering UV pulses with a duration of 5 ns and an energy of 12 mJ, operated at a repetition rate of 10 Hz. The relative fractions of the elements composing the multivitamin drug were determined by comparing the emission spectrum of the laser-produced plume with the spectral radiance computed for a plasma in a local thermodynamic equilibrium. Fair agreement of the measured fractions with those given by the manufacturer was observed for all elements mentioned in the leafl et of the drug. Additional elements such as Ca, Na, Sr, Al, Li, K, and Si were detected and quantifi ed. The present investigations demonstrate that laser-induced breakdown spectroscopy is a viable technique for the quality control of drugs.

  13. Laser-induced periodic surface structuring of biopolymers

    Science.gov (United States)

    Pérez, Susana; Rebollar, Esther; Oujja, Mohamed; Martín, Margarita; Castillejo, Marta

    2013-03-01

    We report here on a systematic study about the formation of laser-induced periodic surface structures (LIPSS) on biopolymers. Self-standing films of the biopolymers chitosan, starch and the blend of chitosan with the synthetic polymer poly (vinyl pyrrolidone), PVP, were irradiated in air with linearly polarized laser beams at 193, 213 and 266 nm, with pulse durations in the range of 6-17 ns. The laser-induced periodic surface structures were topographically characterized by atomic force microscopy and the chemical modifications induced by laser irradiation were inspected via Raman spectroscopy. Formation of LIPSS parallel to the laser polarization direction, with periods similar to the laser wavelength, was observed at efficiently absorbed wavelengths in the case of the amorphous biopolymer chitosan and its blend with PVP, while formation of LIPSS is prevented in the crystalline starch biopolymer.

  14. Laser-induced incandescence calibration via gravimetric sampling

    Science.gov (United States)

    Choi, M. Y.; Vander Wal, R. L.; Zhou, Z.

    1996-01-01

    Absolute calibration of laser-induced incandescence (LII) is demonstrated via comparison of LII signal intensities with gravimetrically determined soot volume fractions. This calibration technique does not rely upon calculated or measured optical characteristics of soot. The variation of the LII signal with gravimetrically measured soot volume fractions ranging from 0.078 to 1.1 ppm established the linearly of the calibration. With the high spatial and temporal resolution capabilities of laser-induced incandescence (LII), the spatial and temporal fluctuations of the soot field within a gravimetric chimney were characterized. Radial uniformity of the soot volume fraction, f(sub v) was demonstrated with sufficient averaging of the single laser-shot LII images of the soot field thus confirming the validity of the calibration method for imaging applications. As illustration, instantaneous soot volume fractions within a Re = 5000 ethylene/air diffusion flame measured via planar LII were established quantitatively with this calibration.

  15. Time-resolved laser-induced breakdown spectroscopy of aluminum

    Institute of Scientific and Technical Information of China (English)

    LIU Xian-yun; ZHANG Wei-jun; WANG Zhen-ya; HAO Li-qing; HUANG Ming-qiang; ZHAO Wen-wu; LONG Bo; Zhao Wei

    2008-01-01

    We develop a system to measure the elemental composition of unprepared samples using laser-induced breakdown spectroscopy (LIBS) in our laboratory, which can be used for the determination of elements in solids, liquids and aerosols. A description of the instrumentation, including laser, sample chamber and detection, is followed by a brief discussion. The time-resolved LIBS of aluminum at atmospheric pressure is presented. At the end, the possibilities and later uses of this technique are briefly discussed.

  16. Laser-Induced Breakdown Spectroscopy: Fundamentals, Applications, and Challenges

    OpenAIRE

    Anabitarte, F.; Cobo, A.; J. M. Lopez-Higuera

    2012-01-01

    Laser-induced breakdown spectroscopy (LIBS) is a technique that provides an accurate in situ quantitative chemical analysis and, thanks to the developments in new spectral processing algorithms in the last decade, has achieved a promising performance as a quantitative chemical analyzer at the atomic level. These possibilities along with the fact that little or no sample preparation is necessary have expanded the application fields of LIBS. In this paper, we review the state of the ar...

  17. Towards Friction Control using laser-induced periodic Surface Structures

    OpenAIRE

    Eichstädt, J.; Römer, G.R.B.E.; Huis in 't Veld, A.J.

    2011-01-01

    This paper aims at contributing to the study of laser-induced periodic surface structures (LIPSS) and the description of their tribological properties in order to facilitate the knowledge for contact mechanical applications. To obtain laser parameters for LIPSS formation, we propose to execute two D2-Experiments. For the transfer of results from static experiments to areas of LIPSS we propose the discrete accumulation of fluences. Areas covered by homogeneously distributed LIPSS were machined...

  18. A Mouse Model for Laser-induced Choroidal Neovascularization.

    Science.gov (United States)

    Shah, Ronil S; Soetikno, Brian T; Lajko, Michelle; Fawzi, Amani A

    2015-12-27

    The mouse laser-induced choroidal neovascularization (CNV) model has been a crucial mainstay model for neovascular age-related macular degeneration (AMD) research. By administering targeted laser injury to the RPE and Bruch's membrane, the procedure induces angiogenesis, modeling the hallmark pathology observed in neovascular AMD. First developed in non-human primates, the laser-induced CNV model has come to be implemented into many other species, the most recent of which being the mouse. Mouse experiments are advantageously more cost-effective, experiments can be executed on a much faster timeline, and they allow the use of various transgenic models. The miniature size of the mouse eye, however, poses a particular challenge when performing the procedure. Manipulation of the eye to visualize the retina requires practice of fine dexterity skills as well as simultaneous hand-eye-foot coordination to operate the laser. However, once mastered, the model can be applied to study many aspects of neovascular AMD such as molecular mechanisms, the effect of genetic manipulations, and drug treatment effects. The laser-induced CNV model, though useful, is not a perfect model of the disease. The wild-type mouse eye is otherwise healthy, and the chorio-retinal environment does not mimic the pathologic changes in human AMD. Furthermore, injury-induced angiogenesis does not reflect the same pathways as angiogenesis occurring in an age-related and chronic disease state as in AMD. Despite its shortcomings, the laser-induced CNV model is one of the best methods currently available to study the debilitating pathology of neovascular AMD. Its implementation has led to a deeper understanding of the pathogenesis of AMD, as well as contributing to the development of many of the AMD therapies currently available.

  19. All-SPEEK flexible supercapacitor exploiting laser-induced graphenization

    Science.gov (United States)

    Lamberti, A.; Serrapede, M.; Ferraro, G.; Fontana, M.; Perrucci, F.; Bianco, S.; Chiolerio, A.; Bocchini, S.

    2017-09-01

    Flexible supercapacitors have emerged as one of the more promising and efficient space-saving energy storage system for portable and wearable electronics. Laser-induced graphenization has been recently proposed as a powerful and scalable method to directly convert a polymeric substrate into a 3D network of few layer graphene as high-performance supercapacitor electrode. Unfortunately this outstanding process has been reported to be feasible only for few thermoplastic polymers, strongly limiting its future developments. Here we show that laser induced graphenization of sulfonated poly(ether ether ketone) (SPEEK) can be obtained and the mechanism of this novel process is proposed. The resulting material can act at the same time as binder-free electrode and current collector. Moreover SPEEK is also used both as separator and polymeric electrolyte allowing the assembling of an all-SPEEK flexible supercapacitor. Chemico-physical characterization provides deep understanding of the laser-induced graphenization process, reported on this polymer for the first time, while the device performance studied by cyclic voltammetry, charging-discharging, and impedance spectroscopy prove the enormous potential of the proposed approach.

  20. Determination of hydrocarbon levels in water via laser-induced acoustics wave

    Science.gov (United States)

    Bidin, Noriah; Hossenian, Raheleh; Duralim, Maisarah; Krishnan, Ganesan; Marsin, Faridah Mohd; Nughro, Waskito; Zainal, Jasman

    2016-04-01

    Hydrocarbon contamination in water is a major environmental concern in terms of foreseen collapse of the natural ecosystem. Hydrocarbon level in water was determined by generating acoustic wave via an innovative laser-induced breakdown in conjunction with high-speed photographic coupling with piezoelectric transducer to trace acoustic wave propagation. A Q-switched Nd:YAG (40 mJ) was focused in cuvette-filled hydrocarbon solution at various concentrations (0-2000 ppm) to induce optical breakdown, shock wave generation and later acoustic wave propagation. A nitro-dye (ND) laser (10 mJ) was used as a flash to illuminate and frozen the acoustic wave propagation. Lasers were synchronised using a digital delay generator. The image of acoustic waves was grabbed and recorded via charged couple device (CCD) video camera at the speed of 30 frames/second with the aid of Matrox software version 9. The optical delay (0.8-10.0 μs) between the acoustic wave formation and its frozen time is recorded through photodetectors. A piezo-electric transducer (PZT) was used to trace the acoustic wave (sound signal), which cascades to a digital oscilloscope. The acoustic speed is calculated from the ratio of acoustic wave radius (1-8 mm) and optical time delay. Acoustic wave speed is found to linearly increase with hydrocarbon concentrations. The acoustic signal generation at higher hydrocarbon levels in water is attributed to supplementary mass transfer and impact on the probe. Integrated high-speed photography with transducer detection system authenticated that the signals indeed emerged from the laser-induced acoustic wave instead of photothermal processes. It is established that the acoustic wave speed in water is used as a fingerprint to detect the hydrocarbon levels.

  1. Multiple structure of a laser-induced underwater shock wave

    CERN Document Server

    Tagawa, Yoshiyuki; Hayasaka, Keisuke; Kameda, Masaharu

    2015-01-01

    The structure of a laser-induced underwater shock wave is examined. Plasma formation, shock-wave expansion, and temporal evolution of shock pressure are observed simultaneously using a combined measurement system that obtains high-resolution nanosecond-order image sequences. In contrast to a well-known spherical-shock model, these detailed measurements reveal a non-spherically-symmteric distribution of pressure peak for a wide range of experimental parameters. The structure is determined to be a collection of multiple spherical shocks originated from elongated plasmas.

  2. Biomedical and environmental applications of laser-induced breakdown spectroscopy

    Indian Academy of Sciences (India)

    V K Unnikrishnan; K S Choudhari; Suresh D Kulkarni; Rajesh Nayak; V B Kartha; C Santhosh; B M Suri

    2014-02-01

    Laser-induced breakdown spectroscopy (LIBS) is an emerging analytical technique with numerous advantages such as rapidity, multi-elemental analysis, minimal sample preparation, minimal destruction, low cost and versatility of being applied to a wide range of materials. In this paper, we report the preliminary observations we obtained using LIBS for clinical and environmental samples. Elemental analysis has been done qualitatively in human teeth samples which show encouraging results. It has also been demonstrated in this paper that LIBS can be very well utilized in field applications such as plastic waste sorting and recycling.

  3. Capillary electrophoresis with laser-induced fluorescence: environmental applications.

    Science.gov (United States)

    Riddick, Lee; Brumley, William C

    2008-01-01

    Capillary electrophoresis (CE), especially free-zone CE, offers a relatively simple separation with moderate selectivity based on the mobility of ions in solution. Laser-induced fluorescence (LIF) detection, an extremely sensitive technique, can be coupled with a variety of separation conditions to achieve sensitive and quantitative results. When these techniques are combined, CE/LIF provides the sensitivity and increased selectivity that makes trace level environmental analysis of fluorescent compounds possible at or below levels typical for gas chromatography (GC)/mass spectrometry (MS). We offer a panoramic review of the role of these tools in solving environmental and related analytical problems before providing a detailed experimental protocol.

  4. Laser-induced fluorescence in high pressure solid propellant flames.

    Science.gov (United States)

    Edwards, T; Weaver, D P; Campbell, D H

    1987-09-01

    The application of laser-induced fluorescence (LIF) to the study of high pressure solid propellant flames is described. The distribution of the OH and CN radicals was determined in several solid propellant flames at pressures up to 3.5 MPa. The greatest difficulty in these measurements was the separation of the desired LIF signals from the large scattering at the laser wavelength from the very optically thick propellant flames. Raman experiments using 308-nm excitation were also attempted in the propellant flames but were unsuccessful due to LIF interferences from OH and NH.

  5. Tissue tearing caused by pulsed laser-induced ablation pressure.

    Science.gov (United States)

    Cummings, J P; Walsh, J T

    1993-02-01

    Pressure induced by ablative pulses of laser radiation is shown to correlate with the mechanical disruption of tissue. The ablation pressure induced during Er:YSGG laser irradiation of skin, liver, and aorta was calculated from a ballistic pendulum-based measurement of recoil momentum. The ejected material and ablation crater were examined grossly and microscopically after ablation. A gas-dynamic model of laser-induced vaporization was used to understand the measured pressures. The results show that mechanical disruption of tissue occurs when the ablation pressure exceeds the strength of the irradiated tissue at sites of intrinsic weakness.

  6. Trace metal mapping by laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, Jozef [ORNL; Novotny, Dr. Karel [Masaryk University; Hrdlicka, A [Brno University of Technology, Czech Republic; Malina, R [Brno University of Technology, Czech Republic; Hartl, M [Brno University of Technology, Czech Republic; Kizek, R [Mendel University of Brno; Adam, V [Mendel University of Brno

    2012-01-01

    Abstract: Laser-Induced Breakdown Spectroscopy (LIBS) is a sensitive optical technique capable of fast multi-elemental analysis of solid, gaseous and liquid samples. The potential applications of lasers for spectrochemical analysis were developed shortly after its invention; however the massive development of LIBS is connected with the availability of powerful pulsed laser sources. Since the late 80s of 20th century LIBS dominated the analytical atomic spectroscopy scene and its application are developed continuously. Here we review the utilization of LIBS for trace elements mapping in different matrices. The main emphasis is on trace metal mapping in biological samples.

  7. Computer simulations of laser-induced melting of aluminum

    Science.gov (United States)

    Tang, Hong; Bai, Mingze; Dou, Yusheng; Ran, Qi; Lo, Glenn V.

    2013-04-01

    Laser-induced solid-to-liquid phase transitions in 100 nm aluminum film were simulated using a hybrid model that combines molecular dynamics (MD) with a continuum description of the laser excitation and a two-temperature method (TTM) to model the relaxation of conduction band electrons. When the laser fluence provides more energy than needed for a complete melting of the film, the phase transition is characterized by an ultrafast collapse of the crystal structure within 2-3 ps. Otherwise, the transition involves a homogeneous nucleation and growth of liquid zones inside the crystal and a heterogeneous propagation of transition fronts from the external surfaces or nucleated liquid zones.

  8. Controlled calibration method for laser induced breakdown spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Li Wang; Chijian Zhang; Yuan Feng

    2008-01-01

    Laser induced breakdown spectroscopy (LIBS) is a potential technique for rapid analysis of samples present in solids, gases and liquids. In the last two decades it was an object of extensive studies. Controlled calibration method used to analysis the LIBS spectra is investigated. Compared with the inner calibration and calibration-free (CF) methods, this new method overcomes "matrix effect", and demonstrates a better ability to cope with the spectra. It is used to analyze natural soil, and errors of the concentration are decreased about 5%. The result shows that the new method is feasible and accurate.

  9. Laser-induced incandescence from laser-heated silicon nanoparticles

    Science.gov (United States)

    Menser, Jan; Daun, Kyle; Dreier, Thomas; Schulz, Christof

    2016-11-01

    This work describes the application of temporally and spectrally resolved laser-induced incandescence to silicon nanoparticles synthesized in a microwave plasma reactor. Optical properties for bulk silicon presented in the literature were extended for nanostructured particles analyzed in this paper. Uncertainties of parameters in the evaporation submodel, as well as measurement noise, are incorporated into the inference process by Bayesian statistics. The inferred nanoparticle sizes agree with results from transmission electron microscopy, and the determined accommodation coefficient matches the values of the preceding study.

  10. Progress in fieldable laser-induced breakdown spectroscopy (LIBS)

    Science.gov (United States)

    Miziolek, Andrzej W.

    2012-06-01

    In recent years there has been great progress in the Laser Induced Breakdown Spectroscopy (LIBS) technology field. Significant advances have been made both in fundamental and applied research as well as in data processing/chemometrics. Improvements in components, most notably lasers/optics and spectrometers are enabling the development of new devices that are suitable for field use. These new commercial devices recently released to the marketplace, as well as ones currently under development, are bringing the potential of LIBS for CBRNE threat analysis into real-world applications.

  11. Selective filling of Photonic Crystal Fibres

    DEFF Research Database (Denmark)

    Nielsen, Kristian; Noordegraaf, Danny; Sørensen, Thorkild

    2005-01-01

    A model for calculating the time necessary for filling one or more specific holes in a photonic crystal fibre is made. This model is verified for water, and its enabling potential is illustrated by a polymer application. Selective filling of the core in an air-guide photonic crystal fibre...

  12. Selective filling of Photonic Crystal Fibres

    DEFF Research Database (Denmark)

    Nielsen, Kristian; Noordegraaf, Danny; Sørensen, Thorkild

    2005-01-01

    A model for calculating the time necessary for filling one or more specific holes in a photonic crystal fibre is made. This model is verified for water, and its enabling potential is illustrated by a polymer application. Selective filling of the core in an air-guide photonic crystal fibre is demo...

  13. Experimental investigation on laser-induced plasma ignition of hydrocarbon fuel in scramjet engine at takeover flight conditions

    Science.gov (United States)

    Li, Xipeng; Liu, Weidong; Pan, Yu; Yang, Leichao; An, Bin

    2017-09-01

    Laser-induced plasma ignition of an ethylene fuelled cavity is successfully conducted in a model scramjet engine combustor with dual cavities. The simulated flight condition corresponds to takeover flight Mach 4, with isolator entrance Mach number of 2.1, the total pressure of 0.65 MPa and stagnation temperature of 947 K. Ethylene is injected 35 mm upstream of cavity flameholder from four orifices with 2-mm-diameter. The 1064 nm laser beam, from a Q-switched Nd:YAG laser source running at 10 Hz and 940 mJ per pulse, is focused into cavity for ignition. High speed photography is used to capture the transient ignition process. The laser-induced gas breakdown, flame kernel generation and propagation are all recorded and ensuing stable supersonic combustion is established in cavity. The highly ionized plasma zone is almost round at starting, and then the surface of the flame kernel is wrinkled severely in 150 μs after the laser pulse due to the strong turbulence flow in cavity. The flame kernel is found rotating anti-clockwise and gradually moves upstream as the entrainment of circulation flow in cavity. The flame is stabilized at the corner of the cavity for about 200 μs, and then spreads from leading edge to trailing edge via the under part of shear layer to fully fill the entire cavity. The corner recirculation zone of cavity is of great importance for flame spreading. Eventually, a cavity shear-layer stabilized combustion is established in the supersonic flow roughly 2.9 ms after the laser pulse. Both the temporal evolution of normalized chemiluminescence intensity and normalized flame area show that the entire ignition process can be divided into four stages, which are referred as turbulent dissipation stage, combustion enhancement stage, reverting stage and combustion stabilization stage. The results show promising potentials of laser induced plasma for ignition in real scramjets.

  14. Laser-Induced Damage Initiation and Growth of Optical Materials

    Directory of Open Access Journals (Sweden)

    Jingxia Yu

    2014-01-01

    Full Text Available The lifetime of optical components is determined by the combination of laser-induced damage initiation probability and damage propagation rate during subsequent laser shots. This paper reviews both theoretical and experimental investigations on laser-induced damage initiation and growth at the surface of optics. The damage mechanism is generally considered as thermal absorption and electron avalanche, which play dominant roles for the different laser pulse durations. The typical damage morphology in the surface of components observed in experiments is also closely related to the damage mechanism. The damage crater in thermal absorption process, which can be estimated by thermal diffusion model, is typical distortion, melting, and ablation debris often with an elevated rim caused by melted material flow and resolidification. However, damage initiated by electron avalanche is often accompanied by generation of plasma, crush, and fracture, which can be explained by thermal explosion model. Damage growth at rear surface of components is extremely severe which can be explained by several models, such as fireball growth, impact crater, brittle fracture, and electric field enhancement. All the physical effects are not independent but mutually coupling. Developing theoretical models of multiphysics coupling are an important trend for future theoretical research. Meanwhile, more attention should be paid to integrated analysis both in theory and experiment.

  15. Direct probing of chromatography columns by laser-induced fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    McGuffin, V.L.

    1992-12-07

    This report summarizes the progress and accomplishments of this research project from September 1, 1989 to February 28, 1993. During this period, we have accomplished all of the primary scientific objectives of the research proposal: (1) constructed and evaluated a laser-induced fluorescence detection system that allows direct examination of the chromatographic column, (2) examined nonequilibrium processes that occur upon solute injection and elution, (3) examined solute retention in liquid chromatography as a function of temperature and pressure, (4) examined solute zone dispersion in liquid chromatography as a function of temperature and pressure, and (5) developed appropriate theoretical models to describe these phenomena. In each of these studies, substantial knowledge has been gained of the fundamental processes that are responsible for chromatographic separations. In addition to these primary research objectives, we have made significant progress in three related areas: (1) examined pyrene as a fluorescent polarity probe insupercritical fluids and liquids as a function of temperature and pressure, (2) developed methods for the class-selective identification of polynuclear aromatic hydrocarbons in coal-derived fluids by microcolumn liquid chromatography with fluorescence quenching detection, and (3) developed methods for the determination of saturated and unsaturated (including omega-3) fatty acids in fish oil extracts by microcolumn liquid chromatography with laser-induced fluorescence detection. In these studies, the advanced separation and detection techniques developed in our laboratory are applied to practical problems of environmental and biomedical significance.

  16. Analysis of Pulverized Coal by Laser-Induced Breakdown Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Laser-induced breakdown spectroscopy (LIBS) has been used to detect atomic species in various environments. The quantitative analysis (C, H, O, N and S) of representative coal samples are being carried out with LIBS, and the effects of particle size are analyzed.A powerful pulse Nd:YAG laser is focused on the coal sample at atmosphere pressure, and the emission spectra from laser-induced plasmas are measured by time-resolved spectroscopy, and the intensity of analyzed spectral lines is obtained through observing the laser plasma with a delay time of 0.4μs. The experimental results show that the slope of calibration curve is nearly 1 when the concentration of the analyzed element is relatively low, and the slope of curve is nearly 0.5 when the concentration of C is higher than other elements. In addition, using the calibration-free model without self-absorption effect, the results show that the decreasing of particle size leads to an increase of the plasma temperature.

  17. Laser-induced fluorescence detection of stomach cancer using hypericin

    Science.gov (United States)

    Dets, Sergiy M.; Buryi, Alexander N.; Melnik, Ivan S.; Joffe, Alexander Y.; Rusina, Tatyana V.

    1996-12-01

    Natural photodynamic pigment hypericin having intrinsic antitumor properties was applied for fluorescence detection of cancer. Clinical investigation of hypericin was performed to ensure high tumor/normal fluorescence contrast in digestion organs. Laser-induced autofluorescence and exogenous fluorescence analysis of normal tissue and stomach adenocarcinoma was performed using helium-cadmium laser (8 mW, 442 nm). Twenty-one patients have undergone procedure of fluorescence detection of tumors before and after photosensitization. For sensitization of patients we used five or seven capsules containing hypericin in amount of 1 mg which have been administered orally. Strong yellow-red fluorescence of hypericin in tissue with maximum at 603 nm and autofluorescence peak at 535 nm gives an intensity ratio I(603 nm)/I(535 nm) of 2 - 2.5 from cancerous tissue and provides 85% specificity. Preliminary in vivo results of auto- and fluorescence analysis using hypericin photosensitization from one patient with esophageal cancer and eleven patients with stomach cancer proven histologically are encouraging and indicate the high reliability of laser-induced fluorescence technique with hypericin in detection of early stage malignant lesions.

  18. Dynamical behavior of laser-induced nanoparticles during remote processing

    Science.gov (United States)

    Scholz, Tobias; Dickmann, Klaus; Ostendorf, Andreas

    2014-02-01

    Laser remote processing is used in a wide field of industrial applications. Among other things, it is characterized by flexible beam guidance in combination with high processing velocities. But in most cases process gas support in the interaction zone is omitted. Consequently, interaction mechanism between the vapor plume and the incident laser radiation can dynamically affect the process stability. Referring to remote welding with high brilliant laser sources having a wavelength around 1 μm, the interaction between the incident laser radiation and formed particles plays an important role. The presented work shows results of the investigation of the laser-induced particle formation during the laser welding of stainless steel with a 2 kW fiber laser under remote conditions. It is therefore concentrated on the dynamical behavior of the laser-induced particle formation and the dependence of the particle formation on the laser beam power. TEM images of formed particles were analyzed. In addition, the radiation of a LED was directed through the vapor plume. On the one hand, the dynamic of the attenuation was considered. On the other hand, the Rayleigh approximation was used in order to evaluate the detected signals.

  19. Laser-induced thermal desorption of aniline from silica surfaces

    Science.gov (United States)

    Voumard, Pierre; Zenobi, Renato

    1995-10-01

    A complete study on the energy partitioning upon laser-induced thermal desorption of aniline from silica surfaces was undertaken. The measurements include characterization of the aniline-quartz adsorption system using temperature-programmed desorption, the extrapolation of quasiequilibrium desorption temperatures to the regime of laser heating rates on the order of 109-1010 K/s by computational means, measurement of the kinetic energy distributions of desorbing aniline using a pump-probe method, and the determination of internal energies with resonance-enhanced multiphoton ionization spectroscopy. The measurements are compared to calculations of the surface temperature rise and the resulting desorption rates, based on a finite-difference mathematical description of pulsed laser heating. While the surface temperature of laser-heated silica reaches about 600-700 K at the time of desorption, the translational temperature of laser-desorbed aniline was measured to be Tkin=420±60 K, Tvib was 360±60 K, and Trot was 350±100 K. These results are discussed using different models for laser-induced thermal desorption from surfaces.

  20. Direct probing of chromatography columns by laser-induced fluorescence

    Science.gov (United States)

    McGuffin, V. L.

    1992-12-01

    This report summarizes the progress and accomplishments of this research project from 1 Sep. 1989 to 28 Feb. 1993. During this period, we have accomplished all of the primary scientific objectives of the research proposal: (1) constructed and evaluated a laser-induced fluorescence detection system that allows direct examination of the chromatographic column, (2) examined nonequilibrium processes that occur upon solute injection and elution, (3) examined solute retention in liquid chromatography as a function of temperature and pressure, (4) examined solute zone dispersion in liquid chromatography as a function of temperature and pressure, and (5) developed appropriate theoretical models to describe these phenomena. In each of these studies, substantial knowledge has been gained of the fundamental processes that are responsible for chromatographic separations. In addition to these primary research objectives, we have made significant progress in three related areas: (1) examined pyrene as a fluorescent polarity probe in supercritical fluids and liquids as a function of temperature and pressure, (2) developed methods for the class-selective identification of polynuclear aromatic hydrocarbons in coal-derived fluids by microcolumn liquid chromatography with fluorescence quenching detection, and (3) developed methods for the determination of saturated and unsaturated (including omega-3) fatty acids in fish oil extracts by microcolumn liquid chromatography with laser-induced fluorescence detection. In these studies, the advanced separation and detection techniques developed in our laboratory are applied to practical problems of environmental and biomedical significance.

  1. Thermal transport in suspended silicon membranes measured by laser-induced transient gratings

    Directory of Open Access Journals (Sweden)

    A. Vega-Flick

    2016-12-01

    Full Text Available Studying thermal transport at the nanoscale poses formidable experimental challenges due both to the physics of the measurement process and to the issues of accuracy and reproducibility. The laser-induced transient thermal grating (TTG technique permits non-contact measurements on nanostructured samples without a need for metal heaters or any other extraneous structures, offering the advantage of inherently high absolute accuracy. We present a review of recent studies of thermal transport in nanoscale silicon membranes using the TTG technique. An overview of the methodology, including an analysis of measurements errors, is followed by a discussion of new findings obtained from measurements on both “solid” and nanopatterned membranes. The most important results have been a direct observation of non-diffusive phonon-mediated transport at room temperature and measurements of thickness-dependent thermal conductivity of suspended membranes across a wide thickness range, showing good agreement with first-principles-based theory assuming diffuse scattering at the boundaries. Measurements on a membrane with a periodic pattern of nanosized holes (135nm indicated fully diffusive transport and yielded thermal diffusivity values in agreement with Monte Carlo simulations. Based on the results obtained to-date, we conclude that room-temperature thermal transport in membrane-based silicon nanostructures is now reasonably well understood.

  2. Photoluminescence from silicon nano-particles synthesized by laser-induced decomposition of silane

    Science.gov (United States)

    Botti, S.; Coppola, R.; Gourbilleau, F.; Rizk, R.

    2000-09-01

    This work deals with photoluminescence study of silicon nanoparticles produced by CO2-laser-induced decomposition of SiH4 mixed to helium in a controlled atmosphere reactor. By adjusting the pressure of both reactor and precursor gas and its dilution rate in helium, we were able to control, to a certain extent, the silicon growth rate and hence the particle diameter. This latter was determined by both small angle neutron scattering techniques and high resolution transmission electron microscopy observations. Particles with mean diameter ranging between 3 and 10 nm were submitted to photoluminescence and infrared absorption spectroscopy measurements. The photoluminescence spectra revealed two main peaks at about 1.7 and 2.1 eV. The peak position of the former was insensitive to the change of particle size, while its intensity increased after oxidation. The latter showed, however, a slight size dependence but had undergone a drastic decrease after oxidation. These features enabled us to ascribe the red peak (1.7 eV) to some radiative surface defect, while the yellow peak (2.1 eV) appeared consistent with an emission from an oxygen-related defect such as the nonbridging oxygen hole center.

  3. Use of a laser-induced fluorescence thermal imaging system for film cooling heat transfer measurement

    Energy Technology Data Exchange (ETDEWEB)

    Chyu, M.K. [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    1995-10-01

    This paper describes a novel approach based on fluorescence imaging of thermographic phosphor that enables the simultaneous determination of both local film effectiveness and local heat transfer on a film-cooled surface. The film cooling model demonstrated consists of a single row of three discrete holes on a flat plate. The transient temperature measurement relies on the temperature-sensitive fluorescent properties of europium-doped lanthanum oxysulfide (La{sub 2}O{sub 2}S:EU{sup 3+}) thermographic phosphor. A series of full-field surface temperatures, mainstream temperatures, and coolant film temperatures were acquired during the heating of a test surface. These temperatures are used to calculate the heat transfer coefficients and the film effectiveness simultaneously. Because of the superior spatial resolution capability for the heat transfer data reduced from these temperature frames, the laser-induced fluorescence (LIF) imaging system, the present study observes the detailed heat transfer characteristics over a film-protected surface. The trend of the results agrees with those obtained using other conventional thermal methods, as well as the liquid crystal imaging technique. One major advantage of this technique is the capability to record a large number of temperature frames over a given testing period. This offers multiple-sample consistency.

  4. Full matrix capture and the total focusing imaging algorithm using laser induced ultrasonic phased arrays

    Science.gov (United States)

    Stratoudaki, Theodosia; Clark, Matt; Wilcox, Paul D.

    2017-02-01

    Laser ultrasonics is a technique where lasers are used for the generation and detection of ultrasound instead of conventional piezoelectric transducers. The technique is broadband, non-contact, and couplant free, suitable for large stand-off distances, inspection of components of complex geometries and hazardous environments. In this paper, array imaging is presented by obtaining the full matrix of all possible laser generation, laser detection combinations in the array (Full Matrix Capture), at the nondestructive, thermoelastic regime. An advanced imaging technique developed for conventional ultrasonic transducers, the Total Focusing Method (TFM), is adapted for laser ultrasonics and then applied to the captured data, focusing at each point of the reconstruction area. In this way, the beamforming and steering of the ultrasound is done during the post processing. A 1-D laser induced ultrasonic phased array is synthesized with significantly improved spatial resolution and defect detectability. In this study, shear waves are used for the imaging, since they are more efficiently produced than longitudinal waves in the nondestructive, thermoelastic regime. Experimental results are presented from nondestructive, laser ultrasonic inspection of aluminum samples with side drilled holes and slots at depths varying between 5 and 20mm from the surface.

  5. Laser-Induced Fluorescence in Gaseous [I[subscript]2] Excited with a Green Laser Pointer

    Science.gov (United States)

    Tellinghuisen, Joel

    2007-01-01

    A green laser pointer could be used in a flashy demonstration of laser-induced fluorescence in the gas phase by directing the beam of the laser through a cell containing [I[subscript]2] at its room temperature vapor pressure. The experiment could be used to provide valuable insight into the requirements for laser-induced fluorescence (LIF) and the…

  6. Thermal conductivity enhancement of laser induced graphene foam upon P3HT infiltration

    Science.gov (United States)

    Smith, M. K.; Luong, D. X.; Bougher, T. L.; Kalaitzidou, K.; Tour, J. M.; Cola, B. A.

    2016-12-01

    Significant research has been dedicated to the exploration of high thermal conductivity polymer composite materials with conductive filler particles for use in heat transfer applications. However, poor particle dispersibility and interfacial phonon scattering have limited the effective composite thermal conductivity. Three-dimensional foams with high ligament thermal conductivity offer a potential solution to the two aforementioned problems but are traditionally fabricated through expensive and/or complex manufacturing methods. Here, laser induced graphene foams, fabricated through a simple and cost effective laser ablation method, are infiltrated with poly(3-hexylthiophene) in a step-wise fashion to demonstrate the impact of polymer on the thermal conductivity of the composite system. Surprisingly, the addition of polymer results in a drastic (250%) improvement in material thermal conductivity, enhancing the graphene foam's thermal conductivity from 0.68 W/m-K to 1.72 W/m-K for the fully infiltrated composite material. Graphene foam density measurements and theoretical models are utilized to estimate the effective ribbon thermal conductivity as a function of polymer filling. Here, it is proposed that the polymer solution acts as a binding material, which draws graphene ligaments together through elastocapillary coalescence and bonds these ligaments upon drying, resulting in greatly reduced contact resistance within the foam and an effective thermal conductivity improvement greater than what would be expected from the addition of polymer alone.

  7. Evaluation of sandstone surface relaxivity using laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Washburn, Kathryn E; Sandor, Magdalena; Cheng, Yuesheng

    2017-02-01

    Nuclear magnetic resonance (NMR) relaxometry is a common technique used to assess the pore size of fluid-filled porous materials in a wide variety of fields. However, the NMR signal itself only provides a relative distribution of pore size. To calculate an absolute pore size distribution from the NMR data, the material's surface relaxivity needs to be known. Here, a method is presented using laser-induced breakdown spectroscopy (LIBS) to evaluate surface relaxivity in sandstones. NMR transverse and longitudinal relaxation was measured on a set of sandstone samples and the surface relaxivity was calculated from the pore size distribution determined with MICP measurements. Using multivariate analysis, it was determined that the LIBS data can predict with good accuracy the longitudinal (R(2)∼0.84) and transverse (R(2)∼0.79) surface relaxivity. Analysis of the regression coefficients shows significant influence from several elements. Some of these are elements previously established to have an effect on surface relaxivity, such as iron and manganese, while others are not commonly associated with surface relaxivity, such as cobalt and titanium. Furthermore, LIBS provides advantages compared to current methods to calibrate surface relaxivity in terms of speed, portability, and sample size requirements. While this paper focuses on geological samples, the method could potentially be expanded to other types of porous materials.

  8. Influence of absorption induced thermal initiation pathway on irradiance threshold for laser induced breakdown

    Science.gov (United States)

    Varghese, Babu; Bonito, Valentina; Jurna, Martin; Palero, Jonathan; Verhagen, Margaret Hortonand Rieko

    2015-01-01

    We investigated the influence of thermal initiation pathway on the irradiance threshold for laser induced breakdown in transparent, absorbing and scattering phantoms. We observed a transition from laser-induced optical breakdown to laser-induced thermal breakdown as the absorption coefficient of the medium is increased. We found that the irradiance threshold after correction for the path length dependent absorption and scattering losses in the medium is lower due to the thermal pathway for the generation of seed electrons compared to the laser-induced optical breakdown. Furthermore, irradiance threshold gradually decreases with the increase in the absorption properties of the medium. Creating breakdown with lower irradiance threshold that is specific at the target chromophore can provide intrinsic target selectivity and improve safety and efficacy of skin treatment methods that use laser induced breakdown. PMID:25909007

  9. Inexpensive laser-induced surface modification in bismuth thin films

    Energy Technology Data Exchange (ETDEWEB)

    Contreras, A. Reyes [Facultad de Ciencias, Universidad Autónoma del Estado de México, Carretera Toluca, Ixtlahuaca Kilómetro 15.5, C.P. 50200 Edo. de México (Mexico); Hautefeuille, M., E-mail: mathieu_h@ciencias.unam.mx [Facultad de Ciencias, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Circuito Exterior S/N, Coyoacán, Ciudad Universitaria, C.P. 04510 D.F. Mexico (Mexico); García, A. Esparza [Fotofísica y Películas Delgadas, Departamento de Tecnociencias, CCADET-UNAM, Circuito exterior s/n C.P. 04510 Cd. Universitaria, D.F. Mexico (Mexico); Mejia, O. Olea [Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM, Carretera Toluca-Atlacomulco, Km 14.5, Unidad El Rosedal, 50200 San Cayetano, Estado de México (Mexico); López, M.A. Camacho [Facultad de Química, Universidad Autónoma del Estado de México, Tollocan s/n, esq. Paseo Colón, Toluca, Estado de México 50110 (Mexico)

    2015-05-01

    Highlights: • Laser-induced microbumps were formed on bismuth films using a simple, low-cost, laser setup. • The patterns, similar to those typically obtained with high-power lasers, were characterized. • Control of laser ablation conditions is critical in the fabrication of surface microbumps. - Abstract: In this work, we present results on texturing a 500 nm thick bismuth film, deposited by sputtering onto a glass slide using a low-cost homemade, near-infrared pulsed laser platform. A 785 nm laser diode of a CD–DVD pickup head was precisely focused on the sample mounted on a motorized two-axis translation stage to generate localized surface microbumps on the bismuth films. This simple method successfully transferred desired micropatterns on the films in a computer-numerical control fashion. Irradiated zones were characterized by atomic force microscopy and scanning electron microscopy. It was observed that final results are strongly dependent on irradiation parameters.

  10. Laser-induced incandescence: Towards quantitative soot volume fraction measurements

    Energy Technology Data Exchange (ETDEWEB)

    Tzannis, A.P.; Wienbeucker, F.; Beaud, P.; Frey, H.-M.; Gerber, T.; Mischler, B.; Radi, P.P. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Laser-Induced Incandescence has recently emerged as a versatile tool for measuring soot volume fraction in a wide range of combustion systems. In this work we investigate the essential features of the method. LII is based on the acquisition of the incandescence of soot when heated through a high power laser pulse. Initial experiments have been performed on a model laboratory flame. The behaviour of the LII signal is studied experimentally. By applying numerical calculations we investigate the possibility to obtain two-dimensional soot volume fraction distributions. For this purpose a combination of LII with other techniques is required. This part is discussed in some extent and the future work is outlined. (author) 4 figs., 3 refs.

  11. Laser-induced vibration of a thin soap film.

    Science.gov (United States)

    Emile, Olivier; Emile, Janine

    2014-09-21

    We report on the vibration of a thin soap film based on the optical radiation pressure force. The modulated low power laser induces a counter gravity flow in a vertical free-standing draining film. The thickness of the soap film is then higher in the upper region than in the lower region of the film. Moreover, the lifetime of the film is dramatically increased by a factor of 2. Since the laser beam only acts mechanically on the film interfaces, such a film can be employed in an optofluidic diaphragm pump, the interfaces behaving like a vibrating membrane and the liquid in-between being the fluid to be pumped. Such a pump could then be used in delicate micro-equipment, in chips where temperature variations are detrimental and even in biological systems.

  12. Apparatus, system, and method for laser-induced breakdown spectroscopy

    Science.gov (United States)

    Effenberger, Jr., Andrew J; Scott, Jill R; McJunkin, Timothy R

    2014-11-18

    In laser-induced breakdown spectroscopy (LIBS), an apparatus includes a pulsed laser configured to generate a pulsed laser signal toward a sample, a constructive interference object and an optical element, each located in a path of light from the sample. The constructive interference object is configured to generate constructive interference patterns of the light. The optical element is configured to disperse the light. A LIBS system includes a first and a second optical element, and a data acquisition module. The data acquisition module is configured to determine an isotope measurement based, at least in part, on light received by an image sensor from the first and second optical elements. A method for performing LIBS includes generating a pulsed laser on a sample to generate light from a plasma, generating constructive interference patterns of the light, and dispersing the light into a plurality of wavelengths.

  13. Femtosecond laser induced phenomena in transparent solid materials

    DEFF Research Database (Denmark)

    Tan, D.Z.; Sharafudeen, K.N.; Yue, Yuanzheng

    2016-01-01

    The interaction of intense femtosecond laser pulses with transparent materials is a topic that has caused great interest of scientists over the past two decades. It will continue to be a fascinating field in the coming years. This is because many challenging fundamental problems have not been...... solved, especially concerning the interaction of strong, ultra-short electromagnetic pulses with matter, and also because potential advanced technologies will emerge due to the impressive capability of the intense femtosecond laser to create new material structures and hence functionalities. When......–matter interaction, and fabricate various integrated micro-devices. In recent years we have witnessed exciting development in understanding and applying femtosecond laser induced phenomena in transparent materials. The interaction of femtosecond laser pulses with transparent materials relies on non...

  14. Laser-induced micro-jetting from armored droplets

    KAUST Repository

    Marston, J. O.

    2015-06-23

    We present findings from an experimental study of laser-induced cavitation within a liquid drop coated with a granular material, commonly referred to as “armored droplets” or “liquid marbles.” The cavitation event follows the formation of plasma after a nanosecond laser pulse. Using ultra-high-speed imaging up to 320,610 fps, we investigate the extremely rapid dynamics following the cavitation, which manifests itself in the form of a plethora of micro-jets emanating simultaneously from the spaces between particles on the surface of the drop. These fine jets break up into droplets with a relatively narrow diameter range, on the order of 10 μm. © 2015, Springer-Verlag Berlin Heidelberg.

  15. Detection of early caries by laser-induced breakdown spectroscopy

    Science.gov (United States)

    Sasazawa, Shuhei; Kakino, Satoko; Matsuura, Yuji

    2015-07-01

    To improve sensitivity of dental caries detection by laser-induced breakdown spectroscopy (LIBS) analysis, it is proposed to utilize emission peaks in the ultraviolet. We newly focused on zinc whose emission peaks exist in ultraviolet because zinc exists at high concentration in the outer layer of enamel. It was shown that by using ratios between heights of an emission peak of Zn and that of Ca, the detection sensitivity and stability are largely improved. It was also shown that early caries are differentiated from healthy part by properly setting a threshold in the detected ratios. The proposed caries detection system can be applied to dental laser systems such as ones based on Er:YAG-lasers. When ablating early caries part by laser light, the system notices the dentist that the ablation of caries part is finished. We also show the intensity of emission peaks of zinc decreased with ablation with Er:YAG laser light.

  16. Prediction of absorption coefficients by pulsed laser induced photoacoustic measurements.

    Science.gov (United States)

    Priya, Mallika; Satish Rao, B S; Ray, Satadru; Mahato, K K

    2014-06-05

    In the current study, a pulsed laser induced photoacoustic spectroscopy setup was designed and developed, aiming its application in clinical diagnostics. The setup was optimized with carbon black samples in water and with various tryptophan concentrations at 281nm excitations. The sensitivity of the setup was estimated by determining minimum detectable concentration of tryptophan in water at the same excitation, and was found to be 0.035mM. The photoacoustic experiments were also performed with various tryptophan concentrations at 281nm excitation for predicting optical absorption coefficients in them and for comparing the outcomes with the spectrophotometrically-determined absorption coefficients for the same samples. Absorption coefficients for a few serum samples, obtained from some healthy female volunteers, were also determined through photoacoustic and spectrophotometric measurements at the same excitations, which showed good agreement between them, indicating its clinical implications.

  17. Picosecond laser-induced water condensation in a cloud chamber.

    Science.gov (United States)

    Sun, Haiyi; Liu, Yonghong; Ju, Jingjing; Tian, Ye; Bai, Yafeng; Liu, Yaoxiang; Du, Shengzhe; Wang, Cheng; Wang, Tiejun; Liu, Jiansheng; Chin, See Leang; Li, Ruxin; Xu, Zhizhan

    2016-09-05

    We investigated water condensation in a laboratory cloud chamber induced by picosecond (ps) laser pulses at ~350 ps (800 nm/1-1000 Hz) with a maximum peak power of ~25 MW. The peak power was much lower than the critical power for self-focusing in air (~3-10 GW depending on the pulse duration). Sparks, airflow and snow formation were observed under different laser energies or repetition rates. It was found that weaker ps laser pulses can also induce water condensation by exploding and breaking down ice crystals and/or water droplets into tiny particles although there was no formation of laser filament. These tiny particles would grow until precipitation in a super-saturation zone due to laser-induced airflow in a cold region with a large temperature gradient.

  18. Printing biological solutions through laser-induced forward transfer

    Science.gov (United States)

    Duocastella, M.; Fernández-Pradas, J. M.; Domínguez, J.; Serra, P.; Morenza, J. L.

    2008-12-01

    Laser-induced forward transfer (LIFT) is a direct-writing technique adequate for the high-resolution printing of a wide range of materials, including biological molecules. In this article, the preparation through LIFT of microarrays of droplets from a solution containing rabbit antibody immunoglobulin G (IgG) is presented. The microarrays were prepared at different laser pulse energy conditions, obtaining microdroplets with a circular and well-defined contour. The transfer process has a double threshold: a minimum energy density required to generate an impulsion on the liquid film, and a minimum pulse energy, which corresponds to the onset for material ejection. In addition, it was demonstrated that the transfer process can be correctly described through a simple model which relates the energy density threshold with the amount of released material. Finally, a fluorescence assay was carried out in which the preservation of the activity of the transferred biomolecules was demonstrated.

  19. Laser-induced breakdown spectroscopy fundamentals and applications

    CERN Document Server

    Noll, Reinhard

    2012-01-01

    This book is a comprehensive source of the fundamentals, process parameters, instrumental components and applications of laser-induced breakdown spectroscopy (LIBS). The effect of multiple pulses on material ablation, plasma dynamics and plasma emission is presented. A heuristic plasma modeling allows to simulate complex experimental plasma spectra. These methods and findings form the basis for a variety of applications to perform quantitative multi-element analysis with LIBS. These application potentials of LIBS have really boosted in the last years ranging from bulk analysis of metallic alloys and non-conducting materials, via spatially resolved analysis and depth profiling covering measuring objects in all physical states: gaseous, liquid and solid. Dedicated chapters present LIBS investigations for these tasks with special emphasis on the methodical and instrumental concepts as well as the optimization strategies for a quantitative analysis. Requirements, concepts, design and characteristic features of LI...

  20. Spectrum standardization for laser-induced breakdown spectroscopy measurements

    CERN Document Server

    Wang, Zhe; West, Logan; Li, Zheng; Ni, Weidou

    2011-01-01

    This paper presents a spectra normalization method for laser-induced breakdown spectroscopy (LIBS) measurements by converting the recorded characteristic line intensity at varying conditions to the intensity under a standard condition with standard plasma temperature, degree of ionization, and total number density of the interested species to reduce the measurement uncertainty. The characteristic line intensities of the interested species are first converted to the intensity at a fixed temperature and standard degree of ionization but varying total number density for each laser pulse analysis. Under this state, if the influence of the variation of plasma morphology is neglected, the sum of multiple spectral line intensities for the measured element can be regarded proportional to the total number density of the specific element, and the fluctuation of the total number density, or the variation of ablation mass, was compensated for by the application of this relationship. In the experiments with 29 brass alloy...

  1. Quantitative analysis of gallstones using laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Singh, Vivek K; Singh, Vinita; Rai, Awadhesh K; Thakur, Surya N; Rai, Pradeep K; Singh, Jagdish P

    2008-11-01

    The utility of laser-induced breakdown spectroscopy (LIBS) for categorizing different types of gallbladder stone has been demonstrated by analyzing their major and minor constituents. LIBS spectra of three types of gallstone have been recorded in the 200-900 nm spectral region. Calcium is found to be the major element in all types of gallbladder stone. The spectrophotometric method has been used to classify the stones. A calibration-free LIBS method has been used for the quantitative analysis of metal elements, and the results have been compared with those obtained from inductively coupled plasma atomic emission spectroscopy (ICP-AES) measurements. The single-shot LIBS spectra from different points on the cross section (in steps of 0.5 mm from one end to the other) of gallstones have also been recorded to study the variation of constituents from the center to the surface. The presence of different metal elements and their possible role in gallstone formation is discussed.

  2. Containerless study of metal evaporation by laser induced fluorescence

    Science.gov (United States)

    Schiffman, Robert A.; Nordine, Paul C.

    1987-01-01

    Laser induced fluorescence (LIF) detection of atomic vapors was used to study evaporation from electromagnetically levitated and CW CO2 laser-heated molybdenum spheres and resistively-heated tungsten filaments. Electromagnetic (EM) levitation in combination with laser heating of tungsten, zirconium, and aluminum specimens was also investigated. LIF intensity vs temperature data were obtained for molybdenum atoms and six electronic states of atomic tungsten, at temperatures up to the melting point of each metal. The detected fraction of the emitted radiation was reduced by self-absorption effects at the higher experimental temperatures. Vaporization enthalpies derived from data for which less than half the LIF intensity was self-absorbed were -636 + or - 24 kJ/g-mol for Mo and 831 + or - 32 kJ/g-mol for W. Space-based applications of EM levitation in combination with radiative heating are discussed.

  3. Laser-induced breakdown spectroscopy theory and applications

    CERN Document Server

    Perini, Umberto

    2014-01-01

    This book deals with the Laser-Induced Breakdown Spectroscopy (LIBS), a widely used atomic emission spectroscopy technique for elemental analysis of materials. It is based on the use of a high-power, short pulse laser excitation. The book is divided into two main sections: the first one concerning theoretical aspects of the technique, the second one describing the state of the art in applications of the technique in different scientific/technological areas. Numerous examples of state of the art applications provide the readers an almost complete scenario of the LIBS technique. The LIBS theoretical aspects are reviewed. The book helps the readers who are less familiar with the technique to understand the basic principles. Numerous examples of state of the art applications give an almost complete scenario of the LIBS technique potentiality. These examples of applications may have a strong impact on future industrial utilization. The authors made important contributions to the development of this field.

  4. Microfabrication of Fresnel zone plates by laser induced solid ablation

    Science.gov (United States)

    Rodrigues, Vanessa R. M.; Thomas, John; Santhosh, Chidangil; Ramachandran, Hema; Mathur, Deepak

    2016-07-01

    A novel and simple single-step method of inscribing optical elements on metal-coated transparent substrates is demonstrated. Laser induced solid ablation (LISA) demands very low laser energies (nJ), as can be amply provided by a femtosecond laser oscillator. Here, LISA is used to write Fresnel zone plates on indium and tungsten coated glass. With up to 100 zones, remarkable agreement is obtained between measured and expected values of the focal length. LISA has enabled attainment of focal spot sizes that are 38% smaller than what would be obtained using conventional lenses of the same numerical aperture. The simplicity with which a high degree of automation can readily be achieved using LISA makes this cost-effective method amenable to a wide variety of applications related to microfabrication of optical elements.

  5. Laser-induced recombination of D{sup +}

    Energy Technology Data Exchange (ETDEWEB)

    Asp, S. [Stockholm Univ. (Sweden). Dept. of Atomic Phys.; Schuch, R. [Stockholm Univ. (Sweden). Dept. of Atomic Phys.; DeWitt, D.R. [Stockholm Univ. (Sweden). Dept. of Atomic Phys.; Biedermann, C. [Stockholm Univ. (Sweden). Dept. of Atomic Phys.; Gao, H. [Stockholm Univ. (Sweden). Dept. of Atomic Phys.; Zong, W. [Stockholm Univ. (Sweden). Dept. of Atomic Phys.; Andler, G. [Manne Siegbahn Laboratory, Stockholm University, S-104 05 Stockholm (Sweden); Justiniano, E. [Stockholm Univ. (Sweden). Dept. of Atomic Phys.

    1996-08-01

    Laser induced recombination into the L shell (n=2) of deuterium was investigated at the heavy-ion cooler storage ring CRYRING for two values of the electron density. The data shows the expected enhancement of radiative recombination, induced by the intense laser field applied, over the spontaneous case. Like in previous measurements, a strong intensity below the photoionization threshold was observed. Qualitatively, this gain is described by an average field induced threshold shift model. However, when reducing the electron density by roughly a factor of two, the effective field increased by an order of magnitude. This surprising result indicates that the precise origin of the observed fields is not simply related to the known field sources. (orig.).

  6. Laser-induced phase separation of silicon carbide

    Science.gov (United States)

    Choi, Insung; Jeong, Hu Young; Shin, Hyeyoung; Kang, Gyeongwon; Byun, Myunghwan; Kim, Hyungjun; Chitu, Adrian M.; Im, James S.; Ruoff, Rodney S.; Choi, Sung-Yool; Lee, Keon Jae

    2016-11-01

    Understanding the phase separation mechanism of solid-state binary compounds induced by laser-material interaction is a challenge because of the complexity of the compound materials and short processing times. Here we present xenon chloride excimer laser-induced melt-mediated phase separation and surface reconstruction of single-crystal silicon carbide and study this process by high-resolution transmission electron microscopy and a time-resolved reflectance method. A single-pulse laser irradiation triggers melting of the silicon carbide surface, resulting in a phase separation into a disordered carbon layer with partially graphitic domains (~2.5 nm) and polycrystalline silicon (~5 nm). Additional pulse irradiations cause sublimation of only the separated silicon element and subsequent transformation of the disordered carbon layer into multilayer graphene. The results demonstrate viability of synthesizing ultra-thin nanomaterials by the decomposition of a binary system.

  7. Elemental Analysis of Soils by Laser Induced Breakdown Spectroscopy

    Science.gov (United States)

    Gondal, Mohammed Ashraf; Dastageer, Mohamed A.

    The chemical and elemental composition of soil is very complex as it contains many constituents like minerals, organic matters, living organisms, fossils, air and water. Considering the diversity of soil contents, quality and usability, a systematic scientific study on the elemental and chemical composition of soil is very important. In order to study the chemical composition of soil, Laser induced breakdown spectroscopy (LIBS) has been applied recently. The important features of LIBS system and its applications for the measurement of nutrients in green house soil, on-line monitoring of remediation process of chromium polluted soil, determination of trace elements in volcanic erupted soil samples collected from ancient cenozoic lava eruption sites and detection of toxic metals in Gulf war oil spill contaminated soil using LIBS are described in this chapter.

  8. Microfabrication of polystyrene microbead arrays by laser induced forward transfer

    Science.gov (United States)

    Palla-Papavlu, Alexandra; Dinca, Valentina; Paraico, Iurie; Moldovan, Antoniu; Shaw-Stewart, James; Schneider, Christof W.; Kovacs, Eugenia; Lippert, Thomas; Dinescu, Maria

    2010-08-01

    In this study we describe a simple method to fabricate microarrays of polystyrene microbeads (PS-μbeads) on Thermanox coverslip surfaces using laser induced forward transfer (LIFT). A triazene polymer layer which acts as a dynamic release layer and propels the closely packed microspheres on the receiving substrate was used for this approach. The deposited features were characterized by optical microscopy, scanning electron microscopy, atomic force microscopy, and Raman spectroscopy. Ultrasonication was used to test the adherence of the transferred beads. In addition, the laser ejection of the PS-μbead pixels was investigated by time resolved shadowgraphy. It was found that stable PS-μbeads micropatterns without any specific immobilization process could be realized by LIFT. These results highlight the increasing role of LIFT in the development of biomaterials, drug delivery, and tissue engineering.

  9. Analysis of fresco by laser induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Caneve, L., E-mail: luisa.caneve@enea.i [ENEA, CR Frascati, Via E. Fermi 45, 00044 Frascati (Italy); Diamanti, A. [Universita ' Tor Vergata' , Dipartimento di Scienze e Tecnologie Chimiche, via della Ricerca Scientifica 1, 00133 Roma (Italy); Grimaldi, F. [ENEA, CR Frascati, Via E. Fermi 45, 00044 Frascati (Italy); Palleschi, G. [Universita ' Tor Vergata' , Dipartimento di Scienze e Tecnologie Chimiche, via della Ricerca Scientifica 1, 00133 Roma (Italy); Spizzichino, V. [ENEA, CR Frascati, Via E. Fermi 45, 00044 Frascati (Italy); Valentini, F. [Universita ' Tor Vergata' , Dipartimento di Scienze e Tecnologie Chimiche, via della Ricerca Scientifica 1, 00133 Roma (Italy)

    2010-08-15

    The laser-based techniques have been shown to be a very powerful tool for artworks characterization and are used in the field of cultural heritage for the offered advantages of minimum invasiveness, in situ applicability and high sensitivity. Laser induced breakdown spectroscopy, in particular, has been applied in this field to many different kinds of ancient materials with successful results. In this work, a fragment of a Roman wall painting from the archaeological area of Pompeii has been investigated by LIBS. The sample elemental composition resulting from LIBS measurements suggested the presence of certain pigments. The ratio of the intensities of different lines related to some characteristic elements is proposed as an indicator for pigment recognition. The depth profiling permitted to put in evidence the presence of successive paint layers with different compositions. A comparison with the results obtained by the microscopy inspection of the sample has been done.

  10. Analysis of fresco by laser induced breakdown spectroscopy

    Science.gov (United States)

    Caneve, L.; Diamanti, A.; Grimaldi, F.; Palleschi, G.; Spizzichino, V.; Valentini, F.

    2010-08-01

    The laser-based techniques have been shown to be a very powerful tool for artworks characterization and are used in the field of cultural heritage for the offered advantages of minimum invasiveness, in situ applicability and high sensitivity. Laser induced breakdown spectroscopy, in particular, has been applied in this field to many different kinds of ancient materials with successful results. In this work, a fragment of a Roman wall painting from the archaeological area of Pompeii has been investigated by LIBS. The sample elemental composition resulting from LIBS measurements suggested the presence of certain pigments. The ratio of the intensities of different lines related to some characteristic elements is proposed as an indicator for pigment recognition. The depth profiling permitted to put in evidence the presence of successive paint layers with different compositions. A comparison with the results obtained by the microscopy inspection of the sample has been done.

  11. Dynamic response of shear thickening fluid under laser induced shock

    Science.gov (United States)

    Wu, Xianqian; Zhong, Fachun; Yin, Qiuyun; Huang, Chenguang

    2015-02-01

    The dynamic response of the 57 vol./vol. % dense spherical silica particle-polyethylene glycol suspension at high pressure was investigated through short pulsed laser induced shock experiments. The measured back free surface velocities by a photonic Doppler velocimetry showed that the shock and the particle velocities decreased while the shock wave transmitted in the shear thickening fluid (STF), from which an equation of state for the STF was obtained. In addition, the peak stress decreased and the absorbed energy increased rapidly with increasing the thickness for a thin layer of the STF, which should be attributed to the impact-jammed behavior through compression of particle matrix, the deformation or crack of the hard-sphere particles, and the volume compression of the particles and the polyethylene glycol.

  12. Multiphoton processes in KrF-laser induced gas breakdown

    Energy Technology Data Exchange (ETDEWEB)

    Poprawe, R.; Herziger, G.

    1986-05-01

    Ionization by multiphoton processes is the dominant generation mechanism of first electrons in the UV-laser-induced gas breakdown. A strongly simplified analytical model for the ion generation rate is used to give an estimate of the threshold intensity I/sub TH/. The result is compared to descriptions by Keldish and Bebb to check its limits of applicability. Solving the kinetic conservation equations for the focus volume gives an estimation of the breakdown intensity where the Debye criterion has been used in the sense of a plasma definition. As an example, breakdown experiments with a KrF-escimer laser have been carried out at different pressures in an argon atmosphere. The pressure dependency of the breakdown threshold intensity and its order of magnitude are predicted by the model.

  13. Optofluidic lens actuated by laser-induced solutocapillary forces

    Science.gov (United States)

    Malyuk, A. Yu.; Ivanova, N. A.

    2017-06-01

    We demonstrate an adaptive liquid lens controlled by laser-induced solutocapillary forces. The liquid droplet serving as a lens is formed in a thin layer of binary liquid mixture by surface tension driven flows caused by the thermal action of laser irradiation. The shape of droplet, its aperture and the focal length are reversibly changed without hysteresis by varying the intensity of the laser beam. The focal length variation range of the droplet-lens lies in between infinity (a flat layer) to 15 mm (a curved interface). The droplet-lens is capable to adjust the in-plane lateral position in response to a displacement of the laser beam. The proposed laser controlled droplet-lens will enable to develop smart liquid optical devices, which can imitate the accommodation reflex and pupillary light reflex of the eye.

  14. Femtosecond laser-induced blazed periodic grooves on metals.

    Science.gov (United States)

    Hwang, Taek Yong; Guo, Chunlei

    2011-07-01

    In this Letter, we generate laser-induced periodic surface structures (LIPSSs) on platinum following femtosecond laser pulse irradiation. For the first time to our knowledge, we study the morphological profile of LIPSSs over a broad incident angular range, and find that the morphological profile of LIPSSs depends significantly on the incident angle of the laser beam. We show that LIPSS grooves become more asymmetric at a larger incident angle, and the morphological profile of LIPSSs formed at an incident angle over 55° eventually resembles that of a blazed grating. Our study suggests that the formation of the blazed groove structures is attributed to the selective ablation of grooves through the asymmetric periodic surface heating following femtosecond pulse irradiation. The blazed grooves are useful for controlling the diffraction efficiency of LIPSSs.

  15. Femtosecond laser-induced surface structures on carbon fibers.

    Science.gov (United States)

    Sajzew, Roman; Schröder, Jan; Kunz, Clemens; Engel, Sebastian; Müller, Frank A; Gräf, Stephan

    2015-12-15

    The influence of different polarization states during the generation of periodic nanostructures on the surface of carbon fibers was investigated using a femtosecond laser with a pulse duration τ=300  fs, a wavelength λ=1025  nm, and a peak fluence F=4  J/cm². It was shown that linear polarization results in a well-aligned periodic pattern with different orders of magnitude concerning their period and an alignment parallel and perpendicular to fiber direction, respectively. For circular polarization, both types of uniform laser-induced periodic surface structures (LIPSS) patterns appear simultaneously with different dominance in dependence on the position at the fiber surface. Their orientation was explained by the polarization-dependent absorptivity and the geometrical anisotropy of the carbon fibers.

  16. Controllable Femtosecond Laser-Induced Dewetting for Plasmonic Applications

    CERN Document Server

    Makarov, Sergey V; Mukhin, Ivan S; Shishkin, Ivan I; Zuev, Dmitriy A; Mozharov, Alexey M; Krasnok, Alexander E; Belov, Pavel A

    2015-01-01

    Dewetting of thin metal films is one of the most widespread method for functional plasmonic nanostructures fabrication. However, simple thermal-induced dewetting does not allow to control degree of nanostructures order without additional lithographic process steps. Here we propose a novel method for lithography-free and large-scale fabrication of plasmonic nanostructures via controllable femtosecond laser-induced dewetting. The method is based on femtosecond laser surface pattering of a thin film followed by a nanoscale hydrodynamical instability, which is found to be very controllable under specific irradiation conditions. We achieve control over degree of nanostructures order by changing laser irradiation parametrs and film thickness. This allowed us to exploit the method for the broad range of applications: resonant light absorbtion and scattering, sensing, and potential improving of thin-film solar cells.

  17. Laser-induced atomic adsorption: a mechanism for nanofilm formation

    CERN Document Server

    Martins, Weliton S; Oriá, Marcos; Chevrollier, Martine

    2013-01-01

    We demonstrate and interpret a technique of laser-induced formation of thin metallic films using alkali atoms on the window of a dense-vapour cell. We show that this intriguing photo-stimulated process originates from the adsorption of Cs atoms via the neutralisation of Cs$^+$ ions by substrate electrons. The Cs$^+$ ions are produced via two-photon absorption by excited Cs atoms very close to the surface, which enables the transfer of the laser spatial intensity profile to the film thickness. An initial decrease of the surface work function is required to guarantee Cs$^+$ neutralisation and results in a threshold in the vapour density. This understanding of the film growth mechanism may facilitate the development of new techniques of laser-controlled lithography, starting from thermal vapours.

  18. Laser induced electron diffraction: a tool for molecular orbital imaging

    CERN Document Server

    Peters, Michel; Charron, Eric; Keller, Arne; Atabek, Osman

    2012-01-01

    We explore the laser-induced ionization dynamics of N2 and CO2 molecules subjected to a few-cycle, linearly polarized, 800\\,nm laser pulse using effective two-dimensional single active electron time-dependent quantum simulations. We show that the electron recollision process taking place after an initial tunnel ionization stage results in quantum interference patterns in the energy resolved photo-electron signals. If the molecule is initially aligned perpendicular to the field polarization, the position and relative heights of the associated fringes can be related to the molecular geometrical and orbital structure, using a simple inversion algorithm which takes into account the symmetry of the initial molecular orbital from which the ionized electron is produced. We show that it is possible to extract inter-atomic distances in the molecule from an averaged photon-electron signal with an accuracy of a few percents.

  19. Heterogeneous atoms in laser-induced synthesis of carbon black

    Science.gov (United States)

    Popovici, E.; Gavrila Florescu, L.; Soare, I.; Scarisoreanu, M.; Sandu, I.; Prodan, G.; Fleaca, C. T.; Morjan, I.; Voicu, I.

    2009-03-01

    Based on a high temperature hydrocarbon/heterogeneous atoms system of well-established composition, the formation of carbon nanostructures by laser-induced pyrolysis is related to the presence of heteroatoms in the reactants. In this paper, the goal is to underline the influence of some heteroatoms on the morphology and functionalizing nanostructured carbon materials by changing both gas composition and experimental parameters, with the focus to drive these materials into a regime where they can naturally interface with the surrounding matter. To investigate, in the versatile laser pyrolysis method, how to in situ modulate - through the presence of heterogeneous atoms - the characteristics of carbon nanopowders claimed by specific application is a challenge. Some preliminary results confirm experimentally their particular behavior during interaction with polymer matrices of some nanocomposites.

  20. Thomson scattering from laser induced plasma in air

    Energy Technology Data Exchange (ETDEWEB)

    Dzierzega, K; Mendys, A [Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Krakow (Poland); Pellerin, S; Thouin, E [GREMI - site de Bourges, Universite d' Orleans, rue Gaston Berger BP 4043, 18028 Bourges (France); Travaille, G; Bousquet, B; Canioni, L [Centre de Physique Moleculaire Optique et Hertzienne, Universite Bordeaux I, 351 Cours de la Liberation, 33405 Talence CEDEX (France); Pokrzywka, B, E-mail: krzysztof.dzierzega@uj.edu.p [Mt. Suhora Observatory, Pedagogical University of Cracow, ul. Podchorazych 2, 30-084 Krakow (Poland)

    2010-05-01

    The laser induced plasma in air produced by 6 ns, 532 nm Nd:YAG pulses with 25 mJ energy was studied using the Thomson scattering method and plasma imaging techniques. Plasma images and Thomson scattered spectra were registered at delay times ranging from 150 ns to 1 {mu}s after the breakdown pulses. The electron density and temperature, as determined in the core of the plasma plume, were found to decrease from 7.4 x 10{sup 17} cm{sup -3} to about 1.03 x 10{sup 17} cm{sup -3} and from 100 900 K to 22 700 K. The highly elevated electron temperatures are the result of plasma heating by the second, probe pulse in the Thomson scattering experiments.

  1. Laser-induced break-up of water jet waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Couty, P.; Hoffmann, P. [EPFL/STI/IOA/Advanced Photonics Laboratory, Lausanne BM, 1015, Lausanne (Switzerland); Spiegel, A.; Vago, N. [Department of Atomic Physics, Budapest University of Technology and Economics, Budafoki ut 8, 1111, Budapest (Hungary); Ugurtas, B.I. [EPFL/STI/IMHEF/Laboratory Fluid Mechanics, Lausanne, 1015, Lausanne (Switzerland)

    2004-06-01

    In this article, an optical method to control the break-up of high-speed liquid jets is proposed. The method consists of focusing the light of a pulsed laser source into the jet behaving as a waveguide. Experiments were performed with the help of a Q-switched frequency doubled Nd:Yag laser ({lambda}=532 nm). The jet diameter was 48 {mu}m and jet velocities from 100 to 200 m/s. To study the laser-induced water jet break-up, observations of the jet coupled with the high power laser were performed for variable coupling and jet velocity conditions. Experimentally determined wavelength and growth rate of the laser-generated disturbance were also compared with the ones predicted by linear stability theory of free jets. (orig.)

  2. Nanocrystalline silicon films prepared by laser-induced crystallization

    Institute of Scientific and Technical Information of China (English)

    傅广生; 于威; 李社强; 侯海虹; 彭英才; 韩理

    2003-01-01

    The excimer laser-induced crystallization technique has been used to investigate the preparation of nanocrystalline silicon (nc-Si) from amorphous silicon (α-Si) thin films on silicon or glass substrates. The α-Si films without hydrogen grown by pulsed-laser deposition are chosen as precursor to avoid the problem of hydrogen effluence during annealing.Analyses have been performed by scanning electron microscopy, atomic force microscopy, Raman scattering spectroscopy and high-resolution transmission-electron microscopy. Experimental results show that silicon nanocrystals can be formed through laser annealing. The growth characters of nc-Si are strongly dependent on the laser energy density. It is shown that the volume of the molten silicon predominates essentially the grain size of nc-Si, and the surface tension of the crystallized silicon is responsible for the mechanism of nc-Si growth.

  3. Theory of laser-induced demagnetization at high temperatures

    KAUST Repository

    Manchon, Aurelien

    2012-02-17

    Laser-induced demagnetization is theoretically studied by explicitly taking into account interactions among electrons, spins, and lattice. Assuming that the demagnetization processes take place during the thermalization of the subsystems, the temperature dynamics is given by the energy transfer between the thermalized interacting baths. These energy transfers are accounted for explicitly through electron-magnon and electron-phonon interactions, which govern the demagnetization time scale. By properly treating the spin system in a self-consistent random phase approximation, we derive magnetization dynamic equations for a broad range of temperature. The dependence of demagnetization on the temperature and pumping laser intensity is calculated in detail. In particular, we show several salient features for understanding magnetization dynamics near the Curie temperature. While the critical slowdown in dynamics occurs, we find that an external magnetic field can restore the fast dynamics. We discuss the implication of the fast dynamics in the application of heat-assisted magnetic recording.

  4. Laser-induced thermoelastic effects can evoke tactile sensations

    Science.gov (United States)

    Jun, Jae-Hoon; Park, Jong-Rak; Kim, Sung-Phil; Min Bae, Young; Park, Jang-Yeon; Kim, Hyung-Sik; Choi, Seungmoon; Jung, Sung Jun; Hwa Park, Seung; Yeom, Dong-Il; Jung, Gu-In; Kim, Ji-Sun; Chung, Soon-Cheol

    2015-06-01

    Humans process a plethora of sensory information that is provided by various entities in the surrounding environment. Among the five major senses, technology for touch, haptics, is relatively young and has relatively limited applications largely due to its need for physical contact. In this article, we suggest a new way for non-contact haptic stimulation that uses laser, which has potential advantages such as mid-air stimulation, high spatial precision, and long working distance. We demonstrate such tactile stimulation can be enabled by laser-induced thermoelastic effects by means of physical and perceptual studies, as well as simulations. In the physical study, the mechanical effect of laser on a human skin sample is detected using low-power radiation in accordance with safety guidelines. Limited increases (reports of the non-nociceptive sensation of laser stimuli.

  5. Analytical study of seashell using laser-induced breakdown spectroscopy

    Science.gov (United States)

    Ying, LI; Yanhong, GU; Ying, Zhang; Yuandong, LI; Yuan, LU

    2017-02-01

    Seashell has been applied as an indicator for ocean research and element analysis of the seashell is used to track biological or environmental evolution. In this work, laser-induced breakdown spectroscopy (LIBS) was applied for elementary analysis of an ezo scallop-shell, and a graphite enrichment method was used as the assistance. It was found that LIBS signal intensity of Ca fluctuated less than 5%, in spite of the sampling positions, and Sr/Ca was related to the shell growth. A similar variation was also found when using a direct LIBS analysis on the shell surface, and it might be more practicable to track shell growth by investigating Sr/Ca ratio with Sr ionic line at 421.6 nm. The obtained results prove that calcium (Ca) is qualified as an internal reference for shell analysis, and LIBS is a potential analytical method for seashell study.

  6. Laser-induced forward transfer of hybrid carbon nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Palla-Papavlu, A. [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen-PSI (Switzerland); National Institute for Lasers, Plasma, and Radiation Physics, Lasers Department, Atomistilor 409, 077125 Magurele (Romania); University of Bucharest, Faculty of Physics, 405 Atomistilor Street, 077125 Magurele (Romania); Filipescu, M., E-mail: mihaela.filipescu@inflpr.ro [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen-PSI (Switzerland); National Institute for Lasers, Plasma, and Radiation Physics, Lasers Department, Atomistilor 409, 077125 Magurele (Romania); Vizireanu, S. [National Institute for Lasers, Plasma, and Radiation Physics, Lasers Department, Atomistilor 409, 077125 Magurele (Romania); Vogt, L. [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen-PSI (Switzerland); Antohe, S. [University of Bucharest, Faculty of Physics, 405 Atomistilor Street, 077125 Magurele (Romania); Academy of Romanian Scientists, Splaiul Independentei 54, 050094 Bucharest (Romania); Dinescu, M. [National Institute for Lasers, Plasma, and Radiation Physics, Lasers Department, Atomistilor 409, 077125 Magurele (Romania); Wokaun, A.; Lippert, T. [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen-PSI (Switzerland)

    2016-06-30

    Highlights: • Rapid prototyping of carbon nanowalls (CNW) and functionalized CNWs is described. • CNW and CNW:SnO{sub 2} pixels are successfully printed by laser-induced forward transfer. • Flexible (polyimide) and rigid (glass) supports are used as substrates. • 4 μm thick CNW and CNW:SnO{sub 2} pixels maintain their morphology and structure after LIFT. - Abstract: Chemically functionalized carbon nanowalls (CNWs) are promising materials for a wide range of applications, i.e. gas sensors, membranes for fuel cells, or as supports for catalysts. However, the difficulty of manipulation of these materials hinders their integration into devices. In this manuscript a procedure for rapid prototyping of CNWs and functionalized CNWs (i.e. decorated with SnO{sub 2} nanoparticles) is described. This procedure enables the use of laser-induced forward transfer (LIFT) as a powerful technique for printing CNWs and CNW:SnO{sub 2} pixels onto rigid and flexible substrates. A morphological study shows that for a large range of laser fluences i.e. 500–700 mJ/cm{sup 2} it is possible to transfer thick (4 μm) CNW and CNW:SnO{sub 2} pixels. Micro-Raman investigation of the transferred pixels reveals that the chemical composition of the CNWs and functionalized CNWs does not change as a result of the laser transfer. Following these results one can envision that CNWs and CNW:SnO{sub 2} pixels obtained by LIFT can be ultimately applied in technological applications.

  7. Influence of template fill in graphoepitaxy DSA

    Science.gov (United States)

    Doise, Jan; Bekaert, Joost; Chan, Boon Teik; Hong, SungEun; Lin, Guanyang; Gronheid, Roel

    2016-03-01

    Directed self-assembly (DSA) of block copolymers (BCP) is considered a promising patterning approach for the 7 nm node and beyond. Specifically, a grapho-epitaxy process using a cylindrical phase BCP may offer an efficient solution for patterning randomly distributed contact holes with sub-resolution pitches, such as found in via and cut mask levels. In any grapho-epitaxy process, the pattern density impacts the template fill (local BCP thickness inside the template) and may cause defects due to respectively over- or underfilling of the template. In order to tackle this issue thoroughly, the parameters that determine template fill and the influence of template fill on the resulting pattern should be investigated. In this work, using three process flow variations (with different template surface energy), template fill is experimentally characterized as a function of pattern density and film thickness. The impact of these parameters on template fill is highly dependent on the process flow, and thus pre-pattern surface energy. Template fill has a considerable effect on the pattern transfer of the DSA contact holes into the underlying layer. Higher fill levels give rise to smaller contact holes and worse critical dimension uniformity. These results are important towards DSA-aware design and show that fill is a crucial parameter in grapho-epitaxy DSA.

  8. Laser marking on soda-lime glass by laser-induced backside wet etching with two-beam interference

    Science.gov (United States)

    Nakazumi, Tomoka; Sato, Tadatake; Narazaki, Aiko; Niino, Hiroyuki

    2016-09-01

    For crack-free marking of glass materials, a beam-scanning laser-induced backside wet etching (LIBWE) process by a beam spot with a fine periodic structure was examined. The fine periodic structure was produced within a beam spot by means of a Mach-Zehnder interferometer incorporated to the optical setup for the beam-scanning LIBWE. A fine structure with a period of 9 µm was observed within the microstructures with a diameter of ca. 40 µm fabricated by a laser shot under double-beam irradiation, and they could be homogeneously fabricated within an area of 800  ×  800 µm. The area filled with the microstructures, including fine periodic structures, could be observed in high contrast under a diffuse, on-axis illumination that was used in commercial QR code readers.

  9. 用深孔爆破成井次品矿充填技术治理采空区%Mined-out Area Treatment with the Deep-hole Blasting Shaft-forming Method and Filling Technique with Poor Ore

    Institute of Scientific and Technical Information of China (English)

    麦尚德; 王洛锋; 李迎峰; 刘亮; 张超

    2012-01-01

    According to the characteristic of large danger goafs in Sandaozhuang open-pit mine, combined the domestic basic methods of mined-out area treatment that are blasting, filling, supporting, closing, mined-out area treatment technique of deep-hole blasting shaft-forming and filling poor mine was discussed, which relates blasting, filling, supporting. According to the existing equipments, design the plan of deep-hole blasting shaft-forming, parameters selection, charge structure and blasting network was studied. Advances the layout principle of equilateral triangle of filling shafts, the geometric model of evaluating filling effect was established, the function relationship among the distance of adjacent walk of filling shafts, height of mined area and filling shaft radius, which is the basement of evaluating filling effect and the multi-shaft design optimization in large mined-out area, was deduces. The mined-out area treatment with the deep-hole blasting shaft-forming is field tested. The experiment result testifies this plan is reasonable and economic. Research and application of the deep-hole blasting shaft-forming method and filling technique improve production safety, the contradiction of large-scale mining and mined-out area treatment is solved. It is useful for two level mineral management Resources comprehensive utilization is achieved, and the purpose of reconciling ore is executed.%针对三道庄露天矿大型高危复合空区的特点,结合国内目前“崩、充、撑、封”等处理采空区的方法,论述了深孔爆破成井次品矿充填处理采空区技本:根据设备现状设计了深孔爆破成井方案,重点研究了参数选择方法、装药结构和爆破网络:提出了充填井等边三角形的布置原则,建立了充填效果评估几何模型,推导出井壁间距与采空区高度、充填井半径之间的函数关系,为评估空区填充效果以及优化大空区多井布置方案奠定了基础:进行了深孔成井处

  10. Theoretical modeling on the laser induced effect of liquid crystal optical phased beam steering

    Science.gov (United States)

    He, Xiaoxian; Wang, Xiangru; Wu, Liang; Tan, Qinggui; Li, Man; Shang, Jiyang; Wu, Shuanghong; Huang, Ziqiang

    2017-01-01

    Non-mechanical laser beam steering has been reported previously in liquid crystal array devices. To be one of the most promising candidates to be practical non-mechanical laser deflector, its laser induced effect still has few theoretical model. In this paper, we propose a theoretical model to analyze this laser induced effect of LC-OPA to evaluate the deterioration on phased beam steering. The model has three parts: laser induced thermal distribution; temperature dependence of material parameters and beam steering deterioration. After these three steps, the far field of laser beam is obtained to demonstrate the steering performance with the respect to the incident laser beam power and beam waist.

  11. Time-Resolved Spectroscopy Diagnostic of Laser-Induced Optical Breakdown

    OpenAIRE

    Parigger, Christian G.; Hornkohl, James O.; László Nemes

    2010-01-01

    Transient laser plasma is generated in laser-induced optical breakdown (LIOB). Here we report experiments conducted with 10.6-micron CO2 laser radiation, and with 1.064-micron fundamental, 0.532-micron frequency-doubled, 0.355-micron frequency-tripled Nd:YAG laser radiation. Characterization of laser induced plasma utilizes laser-induced breakdown spectroscopy (LIBS) techniques. Atomic hydrogen Balmer series emissions show electron number density of 1017 cm−3 measured approximately 10 μs and ...

  12. Theoretical analysis for temperature dependence of laser- induced damage threshold of optical thin films

    Science.gov (United States)

    Mikami, K.; Motokoshi, S.; Somekawa, T.; Jitsuno, T.; Fujita, M.; Tanaka, KA; Azechi, H.

    2016-03-01

    The temperature dependence of the laser-induced damage threshold on optical coatings was studied in detail for laser pulses from 123 K to 473 K at different temperatures. The laser-induced damage threshold increased with decreasing temperatures when we tested long pulses (200 ps and 4 ns). The temperature dependence, however, was reversed for pulses shorter than a few picoseconds (100 fs testing). We propose a scaling model with a flowchart that includes three separate processes: free-electron generation, electron multiplication, and electron heating. Furthermore, we calculated the temperature dependence of laser-induced damage thresholds at different temperatures. Our calculation results agreed well with the experimental results.

  13. Effect of Vacuum on the Laser-Induced Damage of Anti-Reflection Coatings

    Institute of Scientific and Technical Information of China (English)

    LING Xiu-Lan; ZHAO Yuan-An; LI Da-Wei; ZHOU Ming; SHAO Jian-Da; FAN Zheng-Xiu

    2009-01-01

    In the comparison of damage modifications, absorption measurement and energy dispersive x-ray analysis, the effect of vacuum on the laser-induced damage of anti-reflection coatings is analyzed. It is found that vacuum decreases the laser-induced damage threshold of the films. The low laser-induced damage threshold in vacuum environments as opposed to air environments is attributed to water absorption and the formation of the O/Si,O/Zr sub-stoichiometry in the course of laser irradiation.

  14. Laser-induced forward transfer (LIFT) of congruent voxels

    Energy Technology Data Exchange (ETDEWEB)

    Piqué, Alberto, E-mail: pique@nrl.navy.mil [Materials Science and Technology Division, Code 6364, Naval Research Laboratory, Washington, DC 20375 (United States); Kim, Heungsoo; Auyeung, Raymond C.Y.; Beniam, Iyoel [Materials Science and Technology Division, Code 6364, Naval Research Laboratory, Washington, DC 20375 (United States); Breckenfeld, Eric [National Research Council Fellow at the Naval Research Laboratory, Washington, DC 20375 (United States)

    2016-06-30

    Highlights: • Laser-induced forward transfer (LIFT) is demonstrated with high viscosity Ag nanopaste. • Under the right conditions (viscosity and fluence) the transfer of congruent voxels was achieved. • For viscosities under 100 Pa s, congruent voxel transfer of silver nano-suspensions is only possible under a very narrow range of conditions. • For viscosities over 100 Pa s, congruent voxel transfer of silver nano-pastes works over a wider range of fluences, donor substrate thickness, gap distances and voxel areas. • The laser transfer of congruent voxels can be used for printing electronic patterns in particular interconnects. - Abstract: Laser-induced forward transfer (LIFT) of functional materials offers unique advantages and capabilities for the rapid prototyping of electronic, optical and sensor elements. The use of LIFT for printing high viscosity metallic nano-inks and nano-pastes can be optimized for the transfer of voxels congruent with the shape of the laser pulse, forming thin film-like structures non-lithographically. These processes are capable of printing patterns with excellent lateral resolution and thickness uniformity typically found in 3-dimensional stacked assemblies, MEMS-like structures and free-standing interconnects. However, in order to achieve congruent voxel transfer with LIFT, the particle size and viscosity of the ink or paste suspensions must be adjusted to minimize variations due to wetting and drying effects. When LIFT is carried out with high-viscosity nano-suspensions, the printed voxel size and shape become controllable parameters, allowing the printing of thin-film like structures whose shape is determined by the spatial distribution of the laser pulse. The result is a new level of parallelization beyond current serial direct-write processes whereby the geometry of each printed voxel can be optimized according to the pattern design. This work shows how LIFT of congruent voxels can be applied to the fabrication of 2D

  15. Stereoscopic Imaging in Hypersonics Boundary Layers using Planar Laser-Induced Fluorescence

    Science.gov (United States)

    Danehy, Paul M.; Bathel, Brett; Inman, Jennifer A.; Alderfer, David W.; Jones, Stephen B.

    2008-01-01

    Stereoscopic time-resolved visualization of three-dimensional structures in a hypersonic flow has been performed for the first time. Nitric Oxide (NO) was seeded into hypersonic boundary layer flows that were designed to transition from laminar to turbulent. A thick laser sheet illuminated and excited the NO, causing spatially-varying fluorescence. Two cameras in a stereoscopic configuration were used to image the fluorescence. The images were processed in a computer visualization environment to provide stereoscopic image pairs. Two methods were used to display these image pairs: a cross-eyed viewing method which can be viewed by naked eyes, and red/blue anaglyphs, which require viewing through red/blue glasses. The images visualized three-dimensional information that would be lost if conventional planar laser-induced fluorescence imaging had been used. Two model configurations were studied in NASA Langley Research Center's 31-Inch Mach 10 Air Wind tunnel. One model was a 10 degree half-angle wedge containing a small protuberance to force the flow to transition. The other model was a 1/3-scale, truncated Hyper-X forebody model with blowing through a series of holes to force the boundary layer flow to transition to turbulence. In the former case, low flowrates of pure NO seeded and marked the boundary layer fluid. In the latter, a trace concentration of NO was seeded into the injected N2 gas. The three-dimensional visualizations have an effective time resolution of about 500 ns, which is fast enough to freeze this hypersonic flow. The 512x512 resolution of the resulting images is much higher than high-speed laser-sheet scanning systems with similar time response, which typically measure 10-20 planes.

  16. Enhancing the analytical performance of laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cremers, D.A.; Chinni, R.C.; Pichahchy, A.E.; Thornquist, H.K.

    1998-12-31

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The objective of this work is to enhance the analytical capabilities of laser-induced breakdown spectroscopy (LIBS). LIBS is a method of elemental analysis in which powerful laser pulses are focused on a sample to form a microplasma. LIBS is perhaps the most versatile elemental analysis method, applicable to a variety of different real-world analysis problems. Therefore, it is important to enhance the capabilities of the method as much as possible. Accomplishments include: (1) demonstration of signal enhancements of 5--30 times from soils and metals using a double pulse method; (2) development of a model of the observed enhancement obtained using double pulses; (3) demonstration that the analytical performance achievable using low laser-pulse energies (10 and 25 mJ) can match that achievable using an energy of 100 mJ; and (4) demonstration that time-gated detection is not necessary with LIBS.

  17. Laser induced damage studies in mercury cadmium telluride

    Science.gov (United States)

    Garg, Amit; Kapoor, Avinashi; Tripathi, K. N.; Bansal, S. K.

    2007-10-01

    We have investigated laser induced damage at 1.06 μm laser wavelength in diamond paste polished (mirror finish) and carborundum polished Hg0.8Cd0.2Te (MCT) samples with increasing fluence as well as number of pulses. Evolution of damage morphology in two types of samples is quite different. In case of diamond paste polished samples, evolution of damage morphological features is consistent with Hg evaporation with transport of Cd/Te globules towards the periphery of the molten region. Cd/Te globules get accumulated with successive laser pulses at the periphery indicating an accumulation effect. Real time reflectivity (RTR) measurement has been done to understand melt pool dynamics. RTR measurements along with the thermal profile of the melt pool are in good agreement with thermal melting model of laser irradiated MCT samples. In case of carborundum polished samples, laser damage threshold is significantly reduced. Damage morphological features are significantly influenced by surface microstructural condition. From comparison of the morphological features in the two cases, it can be inferred that laser processing of MCT for device applications depends significantly on surface preparation conditions.

  18. Fast analysis of wood preservers using laser induced breakdown spectroscopy

    Science.gov (United States)

    Uhl, A.; Loebe, K.; Kreuchwig, L.

    2001-06-01

    Laser-induced breakdown spectroscopy (LIBS) is used for the investigation of wood preservers in timber and in furniture. Both experiments in laboratory and practical applications in recycling facilities and on a building site prove the new possibilities for the fast detection of harmful agents in wood. A commercial system was developed for mobile laser-plasma-analysis as well as for industrial use in sorting plants. The universal measuring principle in combination with an Echelle optics permits real simultaneous multi-element-analysis in the range of 200-780 nm with a resolution of a few picometers. It enables the user to detect main and trace elements in wood within a few seconds, nearly independent of the matrix, knowing that different kinds of wood show an equal elemental composition. Sample preparation is not required. The quantitative analysis of inorganic wood preservers (containing, e.g. Cu, Cr, B, As, Pb, Hg) has been performed exactly using carbon as reference element. It can be shown that the detection limits for heavy metals in wood are in the ppm-range. Additional information is given concerning the quantitative analysis. Statistical data, e.g. the standard deviation (S.D.), were determined and calibration curves were used for each particular element. A comparison between ICP-AES and LIBS is given using depth profile correction factors regarding the different penetration depths with respect to the different volumes in wood analyzed by both analytical methods.

  19. Evaluation of immunoglobulins in bovine colostrum using laser induced fluorescence.

    Science.gov (United States)

    Abdel-Salam, Z; Abdel Ghany, Sh; Harith, M A

    2014-11-01

    The objective of the present study was to exploit laser induced fluorescence (LIF) as a spectrochemical analytical technique for evaluation of immunoglobulin (IgG) in bovine colostrum. Colostrum samples were collected from different American Holstein cows at different times after calving. Four samples were gathered from each cow; the first three samples were obtained from the first three milkings (colostrum) and the fourth sample (milk) was obtained a week after calving. It has been demonstrated that LIF can be used as a simple, fast, sensitive and less costly spectrochemical analytical technique for qualitative estimation of IgG in colostrum. LIF results have been confirmed via the quantitative evaluation of IgG in the same samples adopting the single radial immunodiffusion conventional technique and a very good agreement has been obtained. Through LIF it was possible to evaluate bovine colostrum after different milking times and to differentiate qualitatively between colostrum from different animals which may reflect their general health status. A fluorescence linear calibration curve for IgG concentrations from 0 up to 120 g L(-1) has been obtained. In addition, it is feasible to adopt this technique for in situ measurements, i.e. in dairy cattle farms as a simple and fast method for evaluation of IgG in bovine colostrum instead of using lengthy and complicated conventional techniques in laboratories.

  20. Laser induced breakdown spectroscopy with picosecond pulse train

    Science.gov (United States)

    Lednev, Vasily N.; Pershin, Sergey M.; Sdvizhenskii, Pavel A.; Grishin, Mikhail Ya; Davydov, Mikhail A.; Stavertiy, Anton Ya; Tretyakov, Roman S.

    2017-02-01

    Picosecond pulse train and nanosecond pulse were compared for laser ablation and laser induced breakdown spectroscopy (LIBS) measurements. A detailed study revealed that the picosecond pulse train ablation improved the quality of laser craters (symmetric crater walls and the absence of large redeposited droplets), which was explained by a smaller heat affected zone and suppression of melt splash. Greater plasma dimensions and brighter plasma emission were observed by gated imaging for picosecond pulse train compared to nanosecond pulse ablation. Increased intensity of atomic and ionic lines in gated and time integrated spectra provided better signal-to-noise ratio for picosecond pulse train sampling. Higher temperature and electron density were detected during first microsecond for the plasma induced by the picosecond pulse train. Improved shot-to-shot reproducibility for atomic/ionic line intensity in the case of picosecond pulse train LIBS was explained by more effective atomization of target material in plasma and better quality of laser craters. Improved precision and limits of detections were determined for picosecond pulse train LIBS due to better reproducibility of laser sampling and increased signal-to-noise ratio.

  1. Laser-induced backside wet cleaning technique for glass substrates

    Science.gov (United States)

    Weng, Tsu-Shien; Tsai, Chwan-Huei

    2014-08-01

    The aim of this paper is to study the laser-induced backside wet cleaning techniques for glass substrates. Two kinds of laser cleaning techniques are proposed in this study. The first involves applying an Nd:YAG laser to the backside of the substrate which is submerged in water. A metal plate is placed below the glass substrate. Most of the laser energy will be absorbed by the metal plate. The metal then vaporizes the water and generates a turbulent bubble flow. The bubble flow removes the alumina particles from the surface of the glass substrate. The second involves using a CO2 laser to generate turbulent bubble flow to remove the particles. Both methods were successfully demonstrated for the removal of submicron particles of 0.5 μm in size. The phenomena of bubble generation and diffusion are presented in the paper. Because the laser is applied to the backside of the substrate, the damage due to the laser heat can be significantly reduced. The quality and efficient of the backside processing is better than those of the front side processing. The proposed techniques have great potential to provide an improved solution for glass cleaning.

  2. Measurement of Irradiated Pyroprocessing Samples via Laser Induced Breakdown Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Phongikaroon, Supathorn [Virginia Commonwealth Univ., Richmond, VA (United States)

    2016-10-31

    The primary objective of this research is to develop an applied technology and provide an assessment to remotely measure and analyze the real time or near real time concentrations of used nuclear fuel (UNF) dissolute in electrorefiners. Here, Laser-Induced Breakdown Spectroscopy (LIBS), in UNF pyroprocessing facilities will be investigated. LIBS is an elemental analysis method, which is based on the emission from plasma generated by focusing a laser beam into the medium. This technology has been reported to be applicable in the media of solids, liquids (includes molten metals), and gases for detecting elements of special nuclear materials. The advantages of applying the technology for pyroprocessing facilities are: (i) Rapid real-time elemental analysis|one measurement/laser pulse, or average spectra from multiple laser pulses for greater accuracy in < 2 minutes; (ii) Direct detection of elements and impurities in the system with low detection limits|element specific, ranging from 2-1000 ppm for most elements; and (iii) Near non-destructive elemental analysis method (about 1 g material). One important challenge to overcome is achieving high-resolution spectral analysis to quantitatively analyze all important fission products and actinides. Another important challenge is related to accessibility of molten salt, which is heated in a heavily insulated, remotely operated furnace in a high radiation environment with an argon atmosphere.

  3. Theory of terahertz emission from femtosecond-laser-induced microplasmas

    Science.gov (United States)

    Thiele, I.; Nuter, R.; Bousquet, B.; Tikhonchuk, V.; Skupin, S.; Davoine, X.; Gremillet, L.; Bergé, L.

    2016-12-01

    We present a theoretical investigation of terahertz (THz) generation in laser-induced gas plasmas. The work is strongly motivated by recent experimental results on microplasmas, but our general findings are not limited to such a configuration. The electrons and ions are created by tunnel ionization of neutral atoms, and the resulting plasma is heated by collisions. Electrons are driven by electromagnetic, convective, and diffusive sources and produce a macroscopic current which is responsible for THz emission. The model naturally includes both ionization current and transition-Cherenkov mechanisms for THz emission, which are usually investigated separately in the literature. The latter mechanism is shown to dominate for single-color multicycle laser pulses, where the observed THz radiation originates from longitudinal electron currents. However, we find that the often discussed oscillations at the plasma frequency do not contribute to the THz emission spectrum. In order to predict the scaling of the conversion efficiency with pulse energy and focusing conditions, we propose a simplified description that is in excellent agreement with rigorous particle-in-cell simulations.

  4. The LILIA (laser induced light ions acceleration) experiment at LNF

    Energy Technology Data Exchange (ETDEWEB)

    Agosteo, S. [Energy Department, Polytechnic of Milan and INFN, Milan (Italy); Anania, M.P. [INFN LNF Frascati, Frascati (Italy); Caresana, M. [Energy Department, Polytechnic of Milan and INFN, Milan (Italy); Cirrone, G.A.P. [INFN LNS Catania, Catania (Italy); De Martinis, C. [Physics Department, University of Milan and INFN, Milan (Italy); Delle Side, D. [LEAS, University of Salento and INFN, Lecce (Italy); Fazzi, A. [Energy Department, Polytechnic of Milan and INFN, Milan (Italy); Gatti, G. [INFN LNF Frascati, Frascati (Italy); Giove, D. [Physics Department, University of Milan and INFN, Milan (Italy); Giulietti, D. [Physics Department, University of Pisa and INFN, Pisa (Italy); Gizzi, L.A.; Labate, L. [INO-CNR and INFN, Pisa (Italy); Londrillo, P. [Physics Department, University of Bologna and INFN, Bologna (Italy); Maggiore, M. [INFN LNL, Legnaro (Italy); Nassisi, V., E-mail: vincenzo.nassisi@le.infn.it [LEAS, University of Salento and INFN, Lecce (Italy); Sinigardi, S. [Physics Department, University of Bologna and INFN, Bologna (Italy); Tramontana, A.; Schillaci, F. [INFN LNS Catania, Catania (Italy); Scuderi, V. [INFN LNS Catania, Catania (Italy); Institute of Physics of the ASCR, Prague (Czech Republic); Turchetti, G. [Physics Department, University of Bologna and INFN, Bologna (Italy); and others

    2014-07-15

    Laser-matter interaction at relativistic intensities opens up new research fields in the particle acceleration and related secondary sources, with immediate applications in medical diagnostics, biophysics, material science, inertial confinement fusion, up to laboratory astrophysics. In particular laser-driven ion acceleration is very promising for hadron therapy once the ion energy will attain a few hundred MeV. The limited value of the energy up to now obtained for the accelerated ions is the drawback of such innovative technique to the real applications. LILIA (laser induced light ions acceleration) is an experiment now running at LNF (Frascati) with the goal of producing a real proton beam able to be driven for significant distances (50–75 cm) away from the interaction point and which will act as a source for further accelerating structure. In this paper the description of the experimental setup, the preliminary results of solid target irradiation and start to end simulation for a post-accelerated beam up to 60 MeV are given.

  5. Determination of flame temperature using laser induced fluorescence (LIF)

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Lina Augusta Martins Ramos da [Instituto Tecnologico de Aeronautica (ITA/DCTA), Sao Jose dos Campos, SP (Brazil); Barreta, Gilberto; Carinhana Junior, Dermeval; Toledo, Antonio Osny de [Instituto de Estudos Avancados (IEAv/DCTA), Sao Jose dos Campos, SP (Brazil)

    2011-07-01

    Full text: Laser Induced Fluorescence, LIF, is one of the most used techniques in combustion diagnostics. The excitation method is based on the spontaneous spectrum from atoms or molecules that were excited by laser radiation. In general, intermediated combustion species, as OH and CH radicals, are used as temperature probes. Usually, several rotational levels are used by tuning the laser afterwards across the corresponding absorption transitions. The emission spectrum is detected in a convenient spectral range. The accuracy of measurements depends on the laser linewidth, the delay between the laser excitation and spectra detection and, mainly, the spectral interval of laser excitation. In this work, OH LIF spectra from stoichiometric LPG (Liquefied Petroleum Gas) flames were obtained using a tuned laser with a spectral range set from 282 nm up to 283 nm. This corresponds to the rotation levels of the 0-1 vibration band of OH radical. The laser energy was ca. 0.2 mJ. The emission spectrum was collected in the spectral range of the 305-310 nm, which corresponds to the region of the 0-0 band. The temperature was determined by the Boltzmann method. This is based on the measurement of the relative peak intensities of the emission spectrum. A plot of natural logarithm of line intensities versus energy level returns a straight line, whose slope is the inverse of the rotational temperature. The flame temperature was ca. 2300 K. This value is consistent with previous results obtained in our laboratory. (author)

  6. Laser-induced forward transfer of hybrid carbon nanostructures

    Science.gov (United States)

    Palla-Papavlu, A.; Filipescu, M.; Vizireanu, S.; Vogt, L.; Antohe, S.; Dinescu, M.; Wokaun, A.; Lippert, T.

    2016-06-01

    Chemically functionalized carbon nanowalls (CNWs) are promising materials for a wide range of applications, i.e. gas sensors, membranes for fuel cells, or as supports for catalysts. However, the difficulty of manipulation of these materials hinders their integration into devices. In this manuscript a procedure for rapid prototyping of CNWs and functionalized CNWs (i.e. decorated with SnO2 nanoparticles) is described. This procedure enables the use of laser-induced forward transfer (LIFT) as a powerful technique for printing CNWs and CNW:SnO2 pixels onto rigid and flexible substrates. A morphological study shows that for a large range of laser fluences i.e. 500-700 mJ/cm2 it is possible to transfer thick (4 μm) CNW and CNW:SnO2 pixels. Micro-Raman investigation of the transferred pixels reveals that the chemical composition of the CNWs and functionalized CNWs does not change as a result of the laser transfer. Following these results one can envision that CNWs and CNW:SnO2 pixels obtained by LIFT can be ultimately applied in technological applications.

  7. Laser-induced forward transfer (LIFT) of congruent voxels

    Science.gov (United States)

    Piqué, Alberto; Kim, Heungsoo; Auyeung, Raymond C. Y.; Beniam, Iyoel; Breckenfeld, Eric

    2016-06-01

    Laser-induced forward transfer (LIFT) of functional materials offers unique advantages and capabilities for the rapid prototyping of electronic, optical and sensor elements. The use of LIFT for printing high viscosity metallic nano-inks and nano-pastes can be optimized for the transfer of voxels congruent with the shape of the laser pulse, forming thin film-like structures non-lithographically. These processes are capable of printing patterns with excellent lateral resolution and thickness uniformity typically found in 3-dimensional stacked assemblies, MEMS-like structures and free-standing interconnects. However, in order to achieve congruent voxel transfer with LIFT, the particle size and viscosity of the ink or paste suspensions must be adjusted to minimize variations due to wetting and drying effects. When LIFT is carried out with high-viscosity nano-suspensions, the printed voxel size and shape become controllable parameters, allowing the printing of thin-film like structures whose shape is determined by the spatial distribution of the laser pulse. The result is a new level of parallelization beyond current serial direct-write processes whereby the geometry of each printed voxel can be optimized according to the pattern design. This work shows how LIFT of congruent voxels can be applied to the fabrication of 2D and 3D microstructures by adjusting the viscosity of the nano-suspension and laser transfer parameters.

  8. Analysis of bakery products by laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Bilge, Gonca; Boyacı, İsmail Hakkı; Eseller, Kemal Efe; Tamer, Uğur; Çakır, Serhat

    2015-08-15

    In this study, we focused on the detection of Na in bakery products by using laser-induced breakdown spectroscopy (LIBS) as a quick and simple method. LIBS experiments were performed to examine the Na at 589 nm to quantify NaCl. A series of standard bread sample pellets containing various concentrations of NaCl (0.025-3.5%) were used to construct the calibration curves and to determine the detection limits of the measurements. Calibration graphs were drawn to indicate functions of NaCl and Na concentrations, which showed good linearity in the range of 0.025-3.5% NaCl and 0.01-1.4% Na concentrations with correlation coefficients (R(2)) values greater than 0.98 and 0.96. The obtained detection limits for NaCl and Na were 175 and 69 ppm, respectively. Performed experimental studies showed that LIBS is a convenient method for commercial bakery products to quantify NaCl concentrations as a rapid and in situ technique.

  9. Liquids microprinting through laser-induced forward transfer

    Energy Technology Data Exchange (ETDEWEB)

    Serra, P. [Universitat de Barcelona, Departament de Fisica Aplicada i Optica, Marti i Franques 1, E-08028 Barcelona (Spain)], E-mail: pserra@ub.edu; Duocastella, M.; Fernandez-Pradas, J.M.; Morenza, J.L. [Universitat de Barcelona, Departament de Fisica Aplicada i Optica, Marti i Franques 1, E-08028 Barcelona (Spain)

    2009-03-01

    Laser-induced forward transfer (LIFT) is a direct-writing technique which allows the deposition of tiny amounts of material from a donor thin film onto a receptor substrate. When LIFT is applied to liquid donor films, the laser radiation affects only a localized fraction of the liquid, thereby impelling the unaffected portion towards the receptor substrate. Thus, transfer takes place with no melting or vaporization of the deposited fraction and, in this way, LIFT can be used to successfully print complex materials like inorganic inks and pastes, biomolecules in solution, and even living cells and microorganisms. In addition, and for a wide range of liquid rheologies, the material can be deposited in the form of circular microdroplets; this provides LIFT with a high degree of spatial resolution leading to feature sizes below 10 {mu}m, and making it competitive in front of conventional printing techniques. In this work, a revision of the main achievements of the LIFT of liquids is carried out, correlating the morphological characteristics of the generated features with the results of the study of the transfer process. Special emphasis is put on the characterization of the dynamics of liquid ejection, which has provided valuable information for the understanding of microdroplets deposition. Thus, new time-resolved imaging analyses have shown a material release behavior which contrasts with most of the previously made assumptions, and that allows clarifying some of the questions open during the study of the LIFT technique.

  10. Production of miniaturized biosensors through laser-induced forward transfer

    Science.gov (United States)

    Fernández-Pradas, J. M.; Duocastella, M.; Colina, M.; Serra, P.; Morenza, J. L.

    2007-05-01

    Lasers are adequate tools for the production of patterns with high spatial resolution owing to the high focusing power of their radiation. Laser induced forward transfer (LIFT) is a direct-writing technique allowing the deposition of tiny amounts of material from a donor thin film through the action of a pulsed laser beam. A laser pulse is focused onto the donor thin film through a transparent support, what results in the transference of a small area of the film onto a receptor substrate that is placed parallel to the film-support system. Although LIFT was originally developed to operate with solid films, it has been demonstrated that deposition is also viable from liquid films. In this case, a small amount of liquid is directly ejected from the film onto the receptor substrate, where it rests deposited in the form of a microdroplet. This makes LIFT adequate for biosensors preparation, since biological solutions can be transferred onto solid substrates to produce micrometric patterns of biomolecules. In this case, the liquid solvent acts as transport vector of the biomolecules. The viability of the technique has been demonstrated through the preparation of functional miniaturized biosensors showing similar performances and higher scales of integration than those prepared through more conventional techniques.

  11. Liquids microprinting through laser-induced forward transfer

    Science.gov (United States)

    Serra, P.; Duocastella, M.; Fernández-Pradas, J. M.; Morenza, J. L.

    2009-03-01

    Laser-induced forward transfer (LIFT) is a direct-writing technique which allows the deposition of tiny amounts of material from a donor thin film onto a receptor substrate. When LIFT is applied to liquid donor films, the laser radiation affects only a localized fraction of the liquid, thereby impelling the unaffected portion towards the receptor substrate. Thus, transfer takes place with no melting or vaporization of the deposited fraction and, in this way, LIFT can be used to successfully print complex materials like inorganic inks and pastes, biomolecules in solution, and even living cells and microorganisms. In addition, and for a wide range of liquid rheologies, the material can be deposited in the form of circular microdroplets; this provides LIFT with a high degree of spatial resolution leading to feature sizes below 10 μm, and making it competitive in front of conventional printing techniques. In this work, a revision of the main achievements of the LIFT of liquids is carried out, correlating the morphological characteristics of the generated features with the results of the study of the transfer process. Special emphasis is put on the characterization of the dynamics of liquid ejection, which has provided valuable information for the understanding of microdroplets deposition. Thus, new time-resolved imaging analyses have shown a material release behavior which contrasts with most of the previously made assumptions, and that allows clarifying some of the questions open during the study of the LIFT technique.

  12. Dust Removal on Mars Using Laser-Induced Breakdown Spectroscopy

    Science.gov (United States)

    Graff, T. G.; Morris, R. V.; Clegg, S. M.; Wiens, R. C.; Anderson, R. B.

    2011-01-01

    Dust coatings on the surface of Mars complicate and, if sufficiently thick, mask the spectral characteristics and compositional determination of underlying material from in situ and remote sensing instrumentation. The Laser-Induced Breakdown Spectroscopy (LIBS) portion of the Chemistry & Camera (ChemCam) instrument, aboard the Mars Science Laboratory (MSL) rover, will be the first active remote sensing technique deployed on Mars able to remove dust. ChemCam utilizes a 5 ns pulsed 1067 nm high-powered laser focused to less than 400 m diameter on targets at distances up to 7 m [1,2]. With multiple laser pulses, dust and weathering coatings can be remotely analyzed and potentially removed using this technique [2,3]. A typical LIBS measurement during MSL surface operations is planned to consist of 50 laser pulses at 14 mJ, with the first 5 to 10 pulses used to analyze as well as remove any surface coating. Additionally, ChemCam's Remote Micro-Imager (RMI) is capable of resolving 200 m details at a distance of 2 m, or 1 mm at 10 m [1,4]. In this study, we report on initial laboratory experiments conducted to characterize the removal of dust coatings using similar LIBS parameters as ChemCam under Mars-like conditions. These experiments serve to better understand the removal of surface dust using LIBS and to facilitate the analysis of ChemCam LIBS spectral data and RMI images.

  13. Analysis of human nails by laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Hosseinimakarem, Zahra; Tavassoli, Seyed Hassan

    2011-05-01

    Laser-induced breakdown spectroscopy (LIBS) is applied to analyze human fingernails using nanosecond laser pulses. Measurements on 45 nail samples are carried out and 14 key species are identified. The elements detected with the present system are: Al, C, Ca, Fe, H, K, Mg, N, Na, O, Si, Sr, Ti as well as CN molecule. Sixty three emission lines have been identified in the spectrum that are dominated by calcium lines. A discriminant function analysis is used to discriminate among different genders and age groups. This analysis demonstrates efficient discrimination among these groups. The mean concentration of each element is compared between different groups. Correlation between concentrations of elements in fingernails is calculated. A strong correlation is found between sodium and potassium while calcium and magnesium levels are inversely correlated. A case report on high levels of sodium and potassium in patients with hyperthyroidism is presented. It is shown that LIBS could be a promising technique for the analysis of nails and therefore identification of health problems.

  14. Thermal desorption from surfaces with laser-induced defects

    Energy Technology Data Exchange (ETDEWEB)

    Szabelski, Pawel; Panczyk, Tomasz; Rudzinski, Wladyslaw

    2002-12-30

    Monte Carlo simulation method was used to mimic surface damage development caused by short laser pulses. The influence of pulsed laser irradiation on the creation of defect concentration was examined in the case of a model surface. In particular, the dependence of the intact surface area on a number of laser scans was studied and compared with the experimental results obtained for Rh(1 1 1) crystal face. Changes in the adsorptivoperties of the surface produced by laser irradiation are explained with the help of a simple geometric model connecting the laser intensity and the disordered area generated by a single laser shot. It was demonstrated that exponential decay of the Low Energy Electron Diffraction (LEED) signal with the number of laser scans, which is observed experimentally, may result directly from the overlapping of the laser spots created on the surface. This effect becomes enhanced when the laser intensity, hence the spot size, increases. The importance of laser-induced defects in the kinetics of catalytic/separation processes was examined in the case of temperature programmed desorption (TPD) spectra from surfaces subjected to a different number of laser shots. The spectra were simulated by employing the Monte Carlo method as well as by application of the absolute rate theory (ART) coupled with the mean field approximation. The results obtained with both methods were in a good agreement even when weak lateral interactions in the adsorbed phase were allowed.

  15. Ultraviolet Laser-induced ignition of RDX single crystal

    Science.gov (United States)

    Yan, Zhonghua; Zhang, Chuanchao; Liu, Wei; Li, Jinshan; Huang, Ming; Wang, Xuming; Zhou, Guorui; Tan, Bisheng; Yang, Zongwei; Li, Zhijie; Li, Li; Yan, Hongwei; Yuan, Xiaodong; Zu, Xiaotao

    2016-02-01

    The RDX single crystals are ignited by ultraviolet laser (355 nm, 6.4 ns) pulses. The laser-induced damage morphology consisted of two distinct regions: a core region of layered fracture and a peripheral region of stripped material surrounding the core. As laser fluence increases, the area of the whole crack region increases all the way, while both the area and depth of the core region increase firstly, and then stay stable over the laser fluence of 12 J/cm2. The experimental details indicate the dynamics during laser ignition process. Plasma fireball of high temperature and pressure occurs firstly, followed by the micro-explosions on the (210) surface, and finally shock waves propagate through the materials to further strip materials outside and yield in-depth cracks in larger surrounding region. The plasma fireball evolves from isotropic to anisotropic under higher laser fluence resulting in the damage expansion only in lateral direction while maintaining the fixed depth. The primary insights into the interaction dynamics between laser and energetic materials can help developing the superior laser ignition technique.

  16. Single cell isolation process with laser induced forward transfer.

    Science.gov (United States)

    Deng, Yu; Renaud, Philippe; Guo, Zhongning; Huang, Zhigang; Chen, Ying

    2017-01-01

    A viable single cell is crucial for studies of single cell biology. In this paper, laser-induced forward transfer (LIFT) was used to isolate individual cell with a closed chamber designed to avoid contamination and maintain humidity. Hela cells were used to study the impact of laser pulse energy, laser spot size, sacrificed layer thickness and working distance. The size distribution, number and proliferation ratio of separated cells were statistically evaluated. Glycerol was used to increase the viscosity of the medium and alginate were introduced to soften the landing process. The role of laser pulse energy, the spot size and the thickness of titanium in energy absorption in LIFT process was theoretically analyzed with Lambert-Beer and a thermal conductive model. After comprehensive analysis, mechanical damage was found to be the dominant factor affecting the size and proliferation ratio of the isolated cells. An orthogonal experiment was conducted, and the optimal conditions were determined as: laser pulse energy, 9 μJ; spot size, 60 μm; thickness of titanium, 12 nm; working distance, 700 μm;, glycerol, 2% and alginate depth, greater than 1 μm. With these conditions, along with continuous incubation, a single cell could be transferred by the LIFT with one shot, with limited effect on cell size and viability. LIFT conducted in a closed chamber under optimized condition is a promising method for reliably isolating single cells.

  17. Laser-induced Forward Transfer of Ag Nanopaste.

    Science.gov (United States)

    Breckenfeld, Eric; Kim, Heungsoo; Auyeung, Raymond C Y; Piqué, Alberto

    2016-03-31

    Over the past decade, there has been much development of non-lithographic methods(1-3) for printing metallic inks or other functional materials. Many of these processes such as inkjet(3) and laser-induced forward transfer (LIFT)(4) have become increasingly popular as interest in printable electronics and maskless patterning has grown. These additive manufacturing processes are inexpensive, environmentally friendly, and well suited for rapid prototyping, when compared to more traditional semiconductor processing techniques. While most direct-write processes are confined to two-dimensional structures and cannot handle materials with high viscosity (particularly inkjet), LIFT can transcend both constraints if performed properly. Congruent transfer of three dimensional pixels (called voxels), also referred to as laser decal transfer (LDT)(5-9), has recently been demonstrated with the LIFT technique using highly viscous Ag nanopastes to fabricate freestanding interconnects, complex voxel shapes, and high-aspect-ratio structures. In this paper, we demonstrate a simple yet versatile process for fabricating a variety of micro- and macroscale Ag structures. Structures include simple shapes for patterning electrical contacts, bridging and cantilever structures, high-aspect-ratio structures, and single-shot, large area transfers using a commercial digital micromirror device (DMD) chip.

  18. Laser-induced breakdown spectroscopy for polymer identification.

    Science.gov (United States)

    Grégoire, Sylvain; Boudinet, Marjorie; Pelascini, Frédéric; Surma, Fabrice; Detalle, Vincent; Holl, Yves

    2011-07-01

    This study aims at differentiating several organic materials, particularly polymers, by laser induced breakdown spectroscopy. The goal is to apply this technique to the fields of polymer recycling and cultural heritage conservation. We worked with some usual polymers families: polyethylene (PE), polypropylene (PP), polyoxymethylene, (POM), poly(vinyl chloride), polytetrafluoroethylene, polyoxyethylene (POE), and polyamide for the aliphatic ones, and poly(butylene terephthalate), acrylonitrile-butadiene-styrene, polystyrene, and polycarbonate for the aromatic ones. The fourth harmonic of a Nd:YAG laser (266 nm) in ambient air at atmospheric pressure was used. A careful analysis of the C(2) Swan system (0,0) band in polymers containing no C-C (POM), few C-C (POE), or aromatic C-C linkages led us to the conclusion that the C(2) signal might be native, i.e., the result of direct ablation from the sample. With use of these results, aliphatic and aromatic polymers could be differentiated. Further data treatments, such as properly chosen line ratios, principal component analysis, and partial least squares regression, were evaluated. It was shown that many polymers could be separated, including PE and PP, despite their similar chemical structures.

  19. Picosecond laser induced periodic surface structure on copper thin films

    Energy Technology Data Exchange (ETDEWEB)

    Huynh, Thi Trang Dai; Petit, Agnès; Semmar, Nadjib, E-mail: nadjib.semmar@univ-orleans.fr

    2014-05-01

    LIPSS (Laser Induced Periodic Surface Structure) formation on copper thin films induced by a picosecond laser beam (Nd:YAG laser at 266 nm, 42 ps and 10 Hz) was studied experimentally. Copper thin films were deposited on glass and silicon substrates by magnetron sputtering. The surface modifications of irradiated zones were analyzed by scanning electron microscopy. Two distinct types of LIPSS were identified with respect to the laser fluence (F), number of laser shots (N) and substrate material. Namely, with a number of laser shots (1000 < N < 10,000) and a fluence of (200 mJ/cm{sup 2} < F < 500 mJ/cm{sup 2}), Low Spatial Frequency LIPSS (LSFL with a spatial period of Λ ∼ 260 nm and an orientation perpendicular to polarization) and High Spatial Frequency LIPSS (HSFL with a spatial period of Λ ∼ 130 nm and an orientation parallel to the polarization) were observed. The regime of regular spikes formation was determined for N ≥ 1000. Moreover, the 2D-map of the relationship among LIPSS formation, laser fluence and number of laser shots on copper thin film with two different substrates was established. A physics interpretation of regular spikes and LIPSS formation on copper thin film induced by ps laser with overlapping multi-shots is proposed based on experimental data and the theory of Plateau-Rayleigh instability.

  20. Fabrication of laser induced periodic surface structure for geometrical engineering

    Energy Technology Data Exchange (ETDEWEB)

    Tsutsumi, Naoto [Department of Macromolecular Science and Engineering, Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo, Kyoto 606-8585 (Japan)], E-mail: tsutsumi@kit.jp; Fujihara, Arata; Nagata, Kazuya [Department of Macromolecular Science and Engineering, Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo, Kyoto 606-8585 (Japan)

    2008-12-31

    The paper presents the highly ordered geometrical structures of laser induced periodic surface structure (LIPSS) in azobenzene urethane polymer (DR19 polymer) from 4-(N,N-dihydroxyethylamino)-4'-nitroazobenzene (Disperse red 19) with tolylene-2,4-diisocyanate (TDI). One or two regulated striped LIPSS was formed in confined spaces between surface relief gratings (SRG) induced by the s-polarized interfered beams. The pitch of LIPSS was one-half or one-third of SRG pitch. Standing wave with some selected mode between SRG in the surface waveguide is responsible for the formation of the regulated striped LIPSS. The crossed illumination of the interfered beams showed the waffle-like structure for s-polarization beam and the egg crate-like (ECL) structure for p-polarized beam. Photoinduced microscopic molecular ordering was also investigated. The linear polarized beam gave the large optical anisotropy in the polymer and the circularly polarized beam produced the chiral structure. The circular dichroism spectra showed the sharp peak due to the circular Bragg reflection from which the chiral pitch was evaluated.

  1. Picosecond laser induced periodic surface structure on copper thin films

    Science.gov (United States)

    Huynh, Thi Trang Dai; Petit, Agnès; Semmar, Nadjib

    2014-05-01

    LIPSS (Laser Induced Periodic Surface Structure) formation on copper thin films induced by a picosecond laser beam (Nd:YAG laser at 266 nm, 42 ps and 10 Hz) was studied experimentally. Copper thin films were deposited on glass and silicon substrates by magnetron sputtering. The surface modifications of irradiated zones were analyzed by scanning electron microscopy. Two distinct types of LIPSS were identified with respect to the laser fluence (F), number of laser shots (N) and substrate material. Namely, with a number of laser shots (1000 LIPSS (LSFL with a spatial period of Λ ∼ 260 nm and an orientation perpendicular to polarization) and High Spatial Frequency LIPSS (HSFL with a spatial period of Λ ∼ 130 nm and an orientation parallel to the polarization) were observed. The regime of regular spikes formation was determined for N ≥ 1000. Moreover, the 2D-map of the relationship among LIPSS formation, laser fluence and number of laser shots on copper thin film with two different substrates was established. A physics interpretation of regular spikes and LIPSS formation on copper thin film induced by ps laser with overlapping multi-shots is proposed based on experimental data and the theory of Plateau-Rayleigh instability.

  2. Femtosecond laser-induced periodic surface structures on silica

    Energy Technology Data Exchange (ETDEWEB)

    Hoehm, S.; Rosenfeld, A. [Max-Born-Institut fuer Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Strasse 2A, D-12489 Berlin (Germany); Krueger, J.; Bonse, J. [BAM Bundesanstalt fuer Materialforschung und-pruefung, Unter den Eichen 87, D-12205 Berlin (Germany)

    2012-07-01

    The formation of laser-induced periodic surface structures (LIPSS) on two different silica polymorphs (single-crystalline synthetic quartz and commercial fused silica glass) upon irradiation in air with multiple linearly polarized single- and double-fs-laser pulse sequences ({tau} = 150 fs pulse duration, {lambda} = 800 nm center wavelength, temporal pulse separation {Delta}t < 40 ps) is studied experimentally and theoretically. Two distinct types of fs-LIPSS [so-called low-spatial-frequency LIPSS (LSFL) and high-spatial-frequency LIPSS (HSFL)] with different spatial periods and orientations were identified. Their appearance was characterized with respect to the experimental parameters peak laser fluence and number of laser pulses per spot. Additionally, the 'dynamics' of the LIPSS formation was addressed in complementary double-fs-pulse experiments with varying delays, revealing a characteristic change of the LSFL periods. The experimental results are interpreted on the basis of a Sipe-Drude model considering the carrier dependence of the optical properties of fs-laser excited silica. This new approach provides an explanation of the LSFL orientation parallel to the laser beam polarisation in silica - as opposed to the behaviour of most other materials.

  3. Coherence in ultrafast laser-induced periodic surface structures

    Science.gov (United States)

    Zhang, Hao; Colombier, Jean-Philippe; Li, Chen; Faure, Nicolas; Cheng, Guanghua; Stoian, Razvan

    2015-11-01

    Ultrafast laser irradiation can trigger anisotropically structured nanoscaled gratinglike arrangements of matter, the laser-induced periodic surface structures (LIPSSs). We demonstrate here that the formation of LIPSS is intrinsically related to the coherence of the laser field. Employing several test materials that allow large optical excursions, we observe the effect of randomizing spatial phase in generating finite domains of ripples. Using three-dimensional finite-difference time-domain methods, we evaluate energy deposition patterns below a material's rough surface and show that modulated pattern, i.e., a spatially ordered electromagnetic solution, results from the coherent superposition of waves. By separating the field scattered from a surface rough topography from the total field, the inhomogeneous energy absorption problem is reduced to a simple interference equation. We further distinguish the contribution of the scattered near field and scattered far field on various types of inhomogeneous energy absorption features. It is found that the inhomogeneous energy absorption which could trigger the low-spatial-frequency LIPSSs (LSFLs) and high-spatial-frequency LIPSSs (HSFLs) of periodicity Λ >λ /Re(n ˜) are due to coherent superposition between the scattered far field (propagation) and the refracted field, while HSFLs of Λ λ ) related to a feedback-driven topography evolution. Those results strongly suggest the electromagnetic interpretation of LIPSSs in interplay with an evolving surface topography.

  4. Refining femtosecond laser induced periodical surface structures with liquid assist

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, L.S. [School of Mechanical and Aerospace Engineering, College of Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Ng, E.Y.K., E-mail: mykng@ntu.edu.sg [School of Mechanical and Aerospace Engineering, College of Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Zheng, H.Y. [Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, 638075 Singapore (Singapore)

    2013-01-01

    Highlights: Black-Right-Pointing-Pointer LIPSS on silicon wafer was made in air and in ethanol environment. Black-Right-Pointing-Pointer Ethanol environment produce cleaner surface ripples. Black-Right-Pointing-Pointer Ethanol environment decrease spatial wavelength of the LIPSS by 30%. Black-Right-Pointing-Pointer More number of pulses produce smaller spatial wavelength in air. Black-Right-Pointing-Pointer Number of pulses do not influence spatial wavelength in ethanol environment. - Abstract: Laser induced periodic surface structures were generated on silicon wafer using femtosecond laser. The medium used in this study is both air and ethanol. The laser process parameters such as wavelength, number of pulse, laser fluence were kept constant for both the mediums. The focus of the study is to analyze spatial wavelength. When generating surface structures with air as a medium and same process parameter of the laser, spatial wavelength results showed a 30% increase compared to ethanol. The cleanliness of the surface generated using ethanol showed considerably less debris than in air. The results observed from the above investigation showed that the medium plays a predominant role in the generation of surface structures.

  5. Unsupervised verification of laser-induced breakdown spectroscopy dataset clustering

    Science.gov (United States)

    Wójcik, Michał R.; Zdunek, Rafał; Antończak, Arkadiusz J.

    2016-12-01

    Laser-induced breakdown spectroscopy is a versatile, optical technique used in a wide range of qualitative and quantitative analyses conducted with the use of various chemometric techniques. The aim of this research is to demonstrate the possibility of unsupervised clustering of an unknown dataset using K-means clustering algorithm, and verifying its input parameters through investigating generalized eigenvalues derived with linear discriminant analysis. In all the cases, principal component analyses have been applied to reduce data dimensionality and shorten computation time of the whole operation. The experiment was conducted on a dataset collected from twenty four different materials divided into six groups: metals, semiconductors, ceramics, rocks, metal alloys and others with the use of a three-channel spectrometer (298.02-628.73nm overall spectral range) and a UV (248nm) excimer laser. Additionally, two more complex groups containing all specimens and all specimens excluding rocks were created. The resulting spaces of eigenvalues were calculated for every group and three different distances in the multidimensional space (cosine, square Euclidean and L1). As expected, the correct numbers of specimens within groups with small deviations were obtained, and the validity of the unsupervised method has thus been proven.

  6. Study of Bacterial Samples Using Laser Induced Breakdown Spectroscopy

    Science.gov (United States)

    W, A. Farooq; M, Atif; W, Tawfik; M, S. Alsalhi; Z, A. Alahmed; M, Sarfraz; J, P. Singh

    2014-12-01

    Laser-induced breakdown spectroscopy (LIBS) technique has been applied to investigate two different types of bacteria, Escherichia coli (B1) and Micrococcus luteus (B2) deposited on glass slides using Spectrolaser 7000. LIBS spectra were analyzed using spectrolaser software. LIBS spectrum of glass substrate was compared with bacteria spectra. Ca, Mg, Na, K, P, S, Cl, Fe, Al, Mn, Cu, C, H and CN-band appeared in bacterial samples in air. Two carbon lines at 193.02 nm, 247.88 nm and one hydrogen line at 656.28 nm with intensity ratios of 1.9, 1.83 and 1.53 appeared in bacterial samples B1 and B2 respectively. Carbon and hydrogen are the important components of the bio-samples like bacteria and other cancer cells. Investigation on LIBS spectra of the samples in He and Ar atmospheres is also presented. Ni lines appeared only in B2 sample in Ar atmosphere. From the present experimental results we are able to show that LIBS technique has a potential in the identification and discrimination of different types of bacteria.

  7. Discrimination of forensic trace evidence using laser induced breakdown spectroscopy

    Science.gov (United States)

    Bridge, Candice Mae

    Elemental analysis in forensic laboratories can be tedious and many trace evidence items are not analyzed to determine their elemental composition. Presently, scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDS) is the primary analytical tool for determining the elemental composition of trace evidence items. However, due to the time it takes to obtain the required vacuum and the limited number of samples that can be analyzed at any one time, SEM-EDS can be impractical for a high volume of evidence items. An alternative instrument that can be used for this type of analysis is laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). While LA-ICP-MS is a very precise and quantitative analytical method that determines elemental composition based on isotopic mass measurements; however, the instrumentation is relatively expensive and therefore is budgetarily prohibitive for many forensic laboratories. It is the purpose of this research to evaluate an inexpensive instrument that can potentially provide rapid elemental analysis for many forensic laboratories. Laser induced breakdown spectroscopy (LIBS) is an analytical method that meets these requirements and offers information about the elemental composition based on ionic, atomic and diatomic molecular emissions.

  8. Characteristics of Ions Emitted from Laser-Induced Silver Plasma

    Institute of Scientific and Technical Information of China (English)

    M. S. RAFIQUE; M. KHALEEQ-UR-RAHMAN; Shakoor MUNAZZA; K. A. BHATTI

    2008-01-01

    In this work, study of laser-induced ions is presented. The plasma was produced by focusing a Nd:YAG laser, with a wavelength of 1064 nm, a pulsed width of 9~14 ns, a power of 1.1 MW and energy of 10 mJ, on silver target in vacuum (10'-3> Torr = 1.3332 Pa). The charac-teristics of ion streams were investigated by CR-39 detectors located at angles of 0°, 30°, 60° and 90° with respect to normal of the target. The distance between the silver target and each detector was 11 cm. The energy of silver ions was found ranging from 1.5 eV to 1.06E4 eV. There was a high concentration of ions with low energy as compared to those with high energy, showing the energy distribution amongst the ions. The flux of ions was maximum in the axial direction which was decreasing with the angle increase with respect to normal of the target, and finally became minimum in the radial direction. Hence the silver ions have shown anisotropic behaviour.

  9. The LILIA (laser induced light ions acceleration) experiment at LNF

    Science.gov (United States)

    Agosteo, S.; Anania, M. P.; Caresana, M.; Cirrone, G. A. P.; De Martinis, C.; Delle Side, D.; Fazzi, A.; Gatti, G.; Giove, D.; Giulietti, D.; Gizzi, L. A.; Labate, L.; Londrillo, P.; Maggiore, M.; Nassisi, V.; Sinigardi, S.; Tramontana, A.; Schillaci, F.; Scuderi, V.; Turchetti, G.; Varoli, V.; Velardi, L.

    2014-07-01

    Laser-matter interaction at relativistic intensities opens up new research fields in the particle acceleration and related secondary sources, with immediate applications in medical diagnostics, biophysics, material science, inertial confinement fusion, up to laboratory astrophysics. In particular laser-driven ion acceleration is very promising for hadron therapy once the ion energy will attain a few hundred MeV. The limited value of the energy up to now obtained for the accelerated ions is the drawback of such innovative technique to the real applications. LILIA (laser induced light ions acceleration) is an experiment now running at LNF (Frascati) with the goal of producing a real proton beam able to be driven for significant distances (50-75 cm) away from the interaction point and which will act as a source for further accelerating structure. In this paper the description of the experimental setup, the preliminary results of solid target irradiation and start to end simulation for a post-accelerated beam up to 60 MeV are given.

  10. Laser-induced breakdown plasma-based sensors

    Science.gov (United States)

    Griffin, Steven T.

    2010-04-01

    Laser Induced Breakdown Spectroscopy (LIBS) is dependent on the interaction between the initiating Laser sequence, the sampled material and the intermediate plasma states. Pulse shaping and timing have been empirically demonstrated to have significant impact on the signal available for active/passive detection and identification. The transient nature of empirical LIBS work makes data collection for optimization an expensive process. Guidance from effective computer simulation represents an alternative. This computational method for CBRNE sensing applications models the Laser, material and plasma interaction for the purpose of performance prediction and enhancement. This paper emphasizes the aspects of light, plasma, and material interaction relevant to portable sensor development for LIBS. The modeling structure emphasizes energy balances and empirical fit descriptions with limited detailed-balance and finite element approaches where required. Dusty plasma from partially decomposed material sample interaction with pulse dynamics is considered. This heuristic is used to reduce run times and computer loads. Computer simulations and some data for validation are presented. A new University of Memphis HPC/super-computer (~15 TFLOPS) is used to enhance simulation. Results coordinated with related effort at Arkansas State University. Implications for ongoing empirical work are presented with special attention paid to the application of compressive sensing for signal processing, feature extraction, and classification.

  11. Hyperspectral laser-induced autofluorescence imaging of dental caries

    Science.gov (United States)

    Bürmen, Miran; Fidler, Aleš; Pernuš, Franjo; Likar, Boštjan

    2012-01-01

    Dental caries is a disease characterized by demineralization of enamel crystals leading to the penetration of bacteria into the dentine and pulp. Early detection of enamel demineralization resulting in increased enamel porosity, commonly known as white spots, is a difficult diagnostic task. Laser induced autofluorescence was shown to be a useful method for early detection of demineralization. The existing studies involved either a single point spectroscopic measurements or imaging at a single spectral band. In the case of spectroscopic measurements, very little or no spatial information is acquired and the measured autofluorescence signal strongly depends on the position and orientation of the probe. On the other hand, single-band spectral imaging can be substantially affected by local spectral artefacts. Such effects can significantly interfere with automated methods for detection of early caries lesions. In contrast, hyperspectral imaging effectively combines the spatial information of imaging methods with the spectral information of spectroscopic methods providing excellent basis for development of robust and reliable algorithms for automated classification and analysis of hard dental tissues. In this paper, we employ 405 nm laser excitation of natural caries lesions. The fluorescence signal is acquired by a state-of-the-art hyperspectral imaging system consisting of a high-resolution acousto-optic tunable filter (AOTF) and a highly sensitive Scientific CMOS camera in the spectral range from 550 nm to 800 nm. The results are compared to the contrast obtained by near-infrared hyperspectral imaging technique employed in the existing studies on early detection of dental caries.

  12. Hydrogen Filling Station

    Energy Technology Data Exchange (ETDEWEB)

    Boehm, Robert F; Sabacky, Bruce; Anderson II, Everett B; Haberman, David; Al-Hassin, Mowafak; He, Xiaoming; Morriseau, Brian

    2010-02-24

    future. Project partners also conducted a workshop on hydrogen safety and permitting. This provided an opportunity for the various permitting agencies and end users to gather to share experiences and knowledge. As a result of this workshop, the permitting process for the hydrogen filling station on the Las Vegas Valley Water District’s land was done more efficiently and those who would be responsible for the operation were better educated on the safety and reliability of hydrogen production and storage. The lessons learned in permitting the filling station and conducting this workshop provided a basis for future hydrogen projects in the region. Continuing efforts to increase the working pressure of electrolysis and efficiency have been pursued. Research was also performed on improving the cost, efficiency and durability of Proton Exchange Membrane (PEM) hydrogen technology. Research elements focused upon PEM membranes, electrodes/catalysts, membrane-electrode assemblies, seals, bipolar plates, utilization of renewable power, reliability issues, scale, and advanced conversion topics. Additionally, direct solar-to-hydrogen conversion research to demonstrate stable and efficient photoelectrochemistry (PEC) hydrogen production systems based on a number of optional concepts was performed. Candidate PEC concepts included technical obstacles such as inefficient photocatalysis, inadequate photocurrent due to non-optimal material band gap energies, rapid electron-hole recombination, reduced hole mobility and diminished operational lifetimes of surface materials exposed to electrolytes. Project Objective 1: Design, build, operate hydrogen filling station Project Objective 2: Perform research and development for utilizing solar technologies on the hydrogen filling station and convert two utility vehicles for use by the station operators Project Objective 3: Increase capacity of hydrogen filling station; add additional vehicle; conduct safety workshop; develop a roadmap for

  13. Hydrogen Filling Station

    Energy Technology Data Exchange (ETDEWEB)

    Boehm, Robert F; Sabacky, Bruce; Anderson II, Everett B; Haberman, David; Al-Hassin, Mowafak; He, Xiaoming; Morriseau, Brian

    2010-02-24

    future. Project partners also conducted a workshop on hydrogen safety and permitting. This provided an opportunity for the various permitting agencies and end users to gather to share experiences and knowledge. As a result of this workshop, the permitting process for the hydrogen filling station on the Las Vegas Valley Water District’s land was done more efficiently and those who would be responsible for the operation were better educated on the safety and reliability of hydrogen production and storage. The lessons learned in permitting the filling station and conducting this workshop provided a basis for future hydrogen projects in the region. Continuing efforts to increase the working pressure of electrolysis and efficiency have been pursued. Research was also performed on improving the cost, efficiency and durability of Proton Exchange Membrane (PEM) hydrogen technology. Research elements focused upon PEM membranes, electrodes/catalysts, membrane-electrode assemblies, seals, bipolar plates, utilization of renewable power, reliability issues, scale, and advanced conversion topics. Additionally, direct solar-to-hydrogen conversion research to demonstrate stable and efficient photoelectrochemistry (PEC) hydrogen production systems based on a number of optional concepts was performed. Candidate PEC concepts included technical obstacles such as inefficient photocatalysis, inadequate photocurrent due to non-optimal material band gap energies, rapid electron-hole recombination, reduced hole mobility and diminished operational lifetimes of surface materials exposed to electrolytes. Project Objective 1: Design, build, operate hydrogen filling station Project Objective 2: Perform research and development for utilizing solar technologies on the hydrogen filling station and convert two utility vehicles for use by the station operators Project Objective 3: Increase capacity of hydrogen filling station; add additional vehicle; conduct safety workshop; develop a roadmap for

  14. Laser-induced periodic surface structures formed on the sidewalls of microholes trepanned by a femtosecond laser

    Science.gov (United States)

    Pham, Khai Xuan; Tanabe, Rie; Ito, Yoshiro

    2013-08-01

    Laser-induced periodic surface structures (LIPSSs) were observed on the sidewalls of 300-μm-diameter holes trepanned on cemented tungsten carbide using femtosecond laser pulses at a wavelength of 800 nm. For a circularly polarized beam, LIPSSs were formed at a period of 300 nm and oriented perpendicularly to the plane of incidence on the sidewalls. For a linearly polarized beam, LIPSS formation was dependent on the relative angle α between the polarization direction and the plane of incidence. For relative angles α from 0° to 70° and from 110° to 180°, LIPSS spacing was 300 nm. However, there were two types of LIPSSs coexisting from 70° to 110°. One had a spacing of 120 nm and the other had a spacing that varied from 500 to 760 nm. It was found that the orientation angle of LIPSSs measured between the LIPSS orientation and the plane of incidence had a nonlinear dependence on α. To understand this dependence, a model was proposed in which LIPSSs are assumed to align perpendicularly to the direction of the absorbed electric field lying in the tangent plane of the sidewall of a drilled hole. The calculated results from this model showed good agreement with the experimental results.

  15. Laser-Induced Emissions Sensor for Soot Mass in Rocket Plumes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A method is proposed to measure soot mass concentration non-intrusively from a distance in a rocket engine exhaust stream during ground tests using laser-induced...

  16. 3D Imaging of Nanoparticle Distribution in Biological Tissue by Laser-Induced Breakdown Spectroscopy

    National Research Council Canada - National Science Library

    Gimenez, Y; Busser, B; Trichard, F; Kulesza, A; Laurent, J M; Zaun, V; Lux, F; Benoit, J M; Panczer, G; Dugourd, P; Tillement, O; Pelascini, F; Sancey, L; Motto-Ros, V

    2016-01-01

    .... The technology used is known as laser-induced breakdown spectroscopy (LIBS) and possesses several advantages such as speed of operation, ease of use and full compatibility with optical microscopy...

  17. Flexible Patterning of Functional Microdot by Laser-Induced Dot Transfer

    National Research Council Canada - National Science Library

    Aiko Narazaki; Ryozo Kurosaki; Tadatake Sato; Hiroyuki Niino

    2014-01-01

      Laser-induced dot transfer (LIDT) is one of promising additive manufacturing techniques because it can realize flexible patterning of micron and submicron-sized dots even at atmospheric room-temperature conditions...

  18. Mechanism of laser-induced plasma shock wave evolution in air

    Institute of Scientific and Technical Information of China (English)

    Zhao Rui; Liang Zhong-Cheng; Han Bing; Zhang Hong-Chao; Xu Rong-Qing; Lu Jian; Ni Xiao-Wu

    2009-01-01

    A theoretical model is proposed to describe the mechanism of laser-induced plasma shock wave evolution in air. To verify the validity of the theoretical model, an optical beam deflection technique is employed to track the plasma shock wave evolution process. The theoretical model and the experimental signals are found to be in good agreement with each other. It is shown that the laser-induced plasma shock wave undergoes formation, increase and decay processes; the increase and the decay processes of the laser-induced plasma shock wave result from the overlapping of the compression wave and the rarefaction wave, respectively. In addition, the laser-induced plasma shock wave speed and pressure distributions, both a function of distance, are presented.

  19. Laser-induced multi-point ignition for enabling high-performance engines

    KAUST Repository

    Chung, Suk-Ho

    2015-01-01

    Various multi-point laser-induced ignition techniques were reviewed, which adopted conical cavity and prechamber configurations. Up to five-point ignitions have been achieved with significant reduction in combustion duration, demonstrating potential increase in combustion system efficiency.

  20. Laser-induced quadrupole-quadrupole collisional energy transfer in Xe-Kr

    Institute of Scientific and Technical Information of China (English)

    Lu Zhen-Zhong; Chen De-Ying; Fan Rong-Wei; Xia Yuan-Qin

    2011-01-01

    By considering the relative velocity distribution function and multipole expansion interaction Hamiltonian, a three-state model for calculating the cross section of laser-induced quadrupole-quadrupole collisional energy transfer is presented. Calculated results in Xe-Kr system show that in the present system, the laser-induced collision process occurs for ~4 ps, which is much shorter than the dipole-dipole laser-induced collisional energy transfer (LICET) process.The spectrum of laser-induced quadrupole-quadrupole collisional energy transfer in Xe-Kr system has wider tunable range in an order of magnitude than the dipole-dipole LICET spectra. The peak cross section decreases and moves to the quasi-static wing with increasing temperature and the full width at half peak of the profile becomes larger as the system temperature increases.

  1. Multivariate Analysis of Laser-Induced Breakdown Spectroscopy for Discrimination between Explosives and Plastics

    Institute of Scientific and Technical Information of China (English)

    WANG Qian-Qian; LIU Kai; ZHAO Hua

    2012-01-01

    A method to distinguish explosives from plastics using laser-induced breakdown spectroscopy is discussed. A model for classification with cross-validation theory is built based on the partial least-square discriminant analysis method. Seven types of plastics and one explosive are used as samples to test the model. The experimental results demonstrate that laser-induced breakdown spectroscopy has the capacity to discriminate explosives from plastics combined with chemometrics methods. The results could be useful for prospective research of laser-induced breakdown spectroscopy on the differentiation of explosives and other materials.%A method to distinguish explosives from plastics using laser-induced breakdown spectroscopy is discussed.A model for classification with cross-validation theory is built based on the partial least-square discriminant analysis method.Seven types of plastics and one explosive are used as samples to test the model.The experimental results demonstrate that laser-induced breakdown spectroscopy has the capacity to discriminate explosives from plastics combined with chemometrics methods.The results could be useful for prospective research of laser-induced breakdown spectroscopy on the differentiation of explosives and other materials.

  2. Laser induced x-ray `RADAR' particle physics model

    Science.gov (United States)

    Lockley, D.; Deas, R.; Moss, R.; Wilson, L. A.; Rusby, D.; Neely, D.

    2016-05-01

    The technique of high-power laser-induced plasma acceleration can be used to generate a variety of diverse effects including the emission of X-rays, electrons, neutrons, protons and radio-frequency radiation. A compact variable source of this nature could support a wide range of potential applications including single-sided through-barrier imaging, cargo and vehicle screening, infrastructure inspection, oncology and structural failure analysis. This paper presents a verified particle physics simulation which replicates recent results from experiments conducted at the Central Laser Facility at Rutherford Appleton Laboratory (RAL), Didcot, UK. The RAL experiment demonstrated the generation of backscattered X-rays from test objects via the bremsstrahlung of an incident electron beam, the electron beam itself being produced by Laser Wakefield Acceleration. A key initial objective of the computer simulation was to inform the experimental planning phase on the predicted magnitude of the backscattered X-rays likely from the test objects. This objective was achieved and the computer simulation was used to show the viability of the proposed concept (Laser-induced X-ray `RADAR'). At the more advanced stages of the experimental planning phase, the simulation was used to gain critical knowledge of where it would be technically feasible to locate key diagnostic equipment within the experiment. The experiment successfully demonstrated the concept of X-ray `RADAR' imaging, achieved by using the accurate timing information of the backscattered X-rays relative to the ultra-short laser pulse used to generate the electron beam. By using fast response X-ray detectors it was possible to derive range information for the test objects being scanned. An X-ray radar `image' (equivalent to a RADAR B-scan slice) was produced by combining individual X-ray temporal profiles collected at different points along a horizontal distance line scan. The same image formation process was used to generate

  3. Laser induced heat source distribution in bio-tissues

    Science.gov (United States)

    Li, Xiaoxia; Fan, Shifu; Zhao, Youquan

    2006-09-01

    During numerical simulation of laser and tissue thermal interaction, the light fluence rate distribution should be formularized and constituted to the source term in the heat transfer equation. Usually the solution of light irradiative transport equation is given in extreme conditions such as full absorption (Lambert-Beer Law), full scattering (Lubelka-Munk theory), most scattering (Diffusion Approximation) et al. But in specific conditions, these solutions will induce different errors. The usually used Monte Carlo simulation (MCS) is more universal and exact but has difficulty to deal with dynamic parameter and fast simulation. Its area partition pattern has limits when applying FEM (finite element method) to solve the bio-heat transfer partial differential coefficient equation. Laser heat source plots of above methods showed much difference with MCS. In order to solve this problem, through analyzing different optical actions such as reflection, scattering and absorption on the laser induced heat generation in bio-tissue, a new attempt was made out which combined the modified beam broaden model and the diffusion approximation model. First the scattering coefficient was replaced by reduced scattering coefficient in the beam broaden model, which is more reasonable when scattering was treated as anisotropic scattering. Secondly the attenuation coefficient was replaced by effective attenuation coefficient in scattering dominating turbid bio-tissue. The computation results of the modified method were compared with Monte Carlo simulation and showed the model provided reasonable predictions of heat source term distribution than past methods. Such a research is useful for explaining the physical characteristics of heat source in the heat transfer equation, establishing effective photo-thermal model, and providing theory contrast for related laser medicine experiments.

  4. Liquid Jet Formation in Laser-Induced Forward Transfer

    Science.gov (United States)

    Brasz, C. Frederik

    Laser-induced forward transfer (LIFT) is a direct-write technique capable of printing precise patterns of a wide variety of materials. In this process, a laser pulse is focused through a transparent support and absorbed in a thin donor film, propelling material onto an adjacent acceptor substrate. For fluid materials, this transfer occurs through the formation of a narrow liquid jet, which eventually pinches off due to surface tension. This thesis examines in detail the fluid mechanics of the jet formation process occurring in LIFT. The main focus is on a variant of LIFT known as blister-actuated LIFT (BA-LIFT), in which the laser pulse is absorbed in an ink-coated polymer layer, rapidly deforming it locally into a blister to induce liquid jet formation. The early-time response of a fluid layer to a deforming boundary is analyzed with a domain perturbation method and potential-flow simulations, revealing scalings for energy and momentum transfer to the fluid and providing physical insight on how and why a jet forms in BA-LIFT. The remaining chapters explore more complex applications and modifications of LIFT. One is the possibility of high-repetition rate printing and limits on time delay and separation between pulses imposed by a tilting effect found for adjacent jets. Another examines a focusing effect achieved by perturbing the interface with ring-shaped disturbances. The third contains an experimental study of LIFT using a silver paste as the donor material instead of a Newtonian liquid. The transfer mechanism is significantly different, although with repeated pulses at one location, a focusing effect is again observed. All three of these chapters investigate how perturbations to the interface can strongly influence the jet formation process.

  5. Laser-induced fluorescence in diagnosis of dental caries

    Science.gov (United States)

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

    2003-09-01

    laser induces better discrimination in deep caries diagnosis.

  6. Application of Laser Induced Breakdown Spectroscopy under Polar Conditions

    Science.gov (United States)

    Clausen, J. L.; Hark, R.; Bol'shakov, A.; Plumer, J.

    2015-12-01

    Over the past decade our research team has evaluated the use of commercial-off-the-shelf laser-induced breakdown spectroscopy (LIBS) for chemical analysis of snow and ice samples under polar conditions. One avenue of research explored LIBS suitability as a detector of paleo-climate proxy indicators (Ca, K, Mg, and Na) in ice as it relates to atmospheric circulation. LIBS results revealed detection of peaks for C and N, consistent with the presence of organic material, as well as major ions (Ca, K, Mg, and Na) and trace metals (Al, Cu, Fe, Mn, Ti). The detection of Ca, K, Mg, and Na confirmed that LIBS has sufficient sensitivity to be used as a tool for characterization of paleo-climate proxy indicators in ice-core samples. Techniques were developed for direct analysis of ice as well as indirect measurements of ice via melting and filtering. Pitfalls and issues of direct ice analysis using several cooling techniques to maintain ice integrity will be discussed. In addition, a new technique, laser ablation molecular isotopic spectroscopy (LAMIS) was applied to detection of hydrogen and oxygen isotopes in ice as isotopic analysis of ice is the main tool in paleoclimatology and glaciology studies. Our results demonstrated that spectra of hydroxyl isotopologues 16OH, 18OH, and 16OD can be recorded with a compact spectrograph to determine hydrogen and oxygen isotopes simultaneously. Quantitative isotopic calibration for ice analysis can be accomplished using multivariate chemometric regression as previously realized for water vapor. Analysis with LIBS and LAMIS required no special sample preparation and was about ten times faster than analysis using ICP-MS. Combination of the two techniques in one portable instrument for in-field analysis appears possible and would eliminate the logistical and cost issues associated with ice core management.

  7. Diamond detectors with laser induced surface graphite electrodes

    Science.gov (United States)

    Komlenok, M.; Bolshakov, A.; Ralchenko, V.; Konov, V.; Conte, G.; Girolami, M.; Oliva, P.; Salvatori, S.

    2016-11-01

    We report on the response of metal-less CVD polycrystalline-diamond pixel sensors under β-particles irradiation. A 21×21 array of 0.18×0.18 mm2 pixels was realized on one side of a 10.0×10.0×0.5 mm3 polycrystalline diamond substrate by means of laser induced surface graphitization. With the same technique, a large graphite contact, used for detector biasing, was fabricated on the opposite side. A coincidence detecting method was used with two other reference polycrystalline diamond detectors for triggering, instead of commonly used scintillators, positioned in the front and on the back of the sensor-array with respect to the impinging particles trajectory. The collected charge distribution at each pixel was analyzed as a function of the applied bias. No change in the pulse height distribution was recorded by inverting the bias voltage polarity, denoting contacts ohmicity and symmetry. A fairly good pixel response uniformity was obtained: the collected charge most probable value saturates for all the pixels at an electric field strength of about ±0.6 V/μm. Under saturation condition, the average collected charge was equal to =1.64±0.02 fC, implying a charge collection distance of about 285 μm. A similar result, within 2%, was also obtained for 400 MeV electrons at beam test facility at INFN Frascati National Laboratory. Experimental results highlighted that more than 84% of impinging particles involved only one pixel, with no significant observed cross-talk effects.

  8. Characterisation of estuarine intertidal macroalgae by laser-induced fluorescence

    Science.gov (United States)

    Gameiro, Carla; Utkin, Andrei B.; Cartaxana, Paulo

    2015-12-01

    The article reports the application of laser-induced fluorescence (LIF) for the assessment of macroalgae communities of estuarine intertidal areas. The method was applied for the characterisation of fifteen intertidal macroalgae species of the Tagus estuary, Portugal, and adjacent coastal area. Three bands characterised the LIF spectra of red macroalgae with emission maxima in the ranges 577-583 nm, 621-642 nm and 705-731 nm. Green and brown macroalgae showed one emission maximum in the red region (687-690 nm) and/or one in the far-red region (726-732 nm). Characteristics of LIF emission spectra were determined by differences in the main fluorescing pigments: phycoerythrin, phycocyanin and chlorophyll a (Chl a). In the green and brown macroalgae groups, the relative significance of the two emission maxima seems to be related to the thickness of the photosynthetic layer. In thick macroalgae, like Codium tomentosum or Fucus vesiculosus, the contribution of the far-red emission fluorescence peak was more significant, most probably due to re-absorption of the emitted red Chl a fluorescence within the dense photosynthetic layer. Similarly, an increase in the number of layers of the thin-blade green macroalgae Ulva rigida caused a shift to longer wavelengths of the red emission maximum and the development of a fluorescence peak at the far-red region. Water loss from Ulva's algal tissue also led to a decrease in the red/far-red Chl fluorescence ratio (F685/F735), indicating an increase in the density of chloroplasts in the shrinking macroalgal tissue during low tide exposure.

  9. Novel Applications of Laser-Induced Breakdown Spectroscopy.

    Science.gov (United States)

    Bauer, Amy J Ray; Buckley, Steven G

    2017-04-01

    The goal of this review article is to provide a description of recent and novel laser-induced breakdown spectroscopy (LIBS) applications and developments, especially those discussed during the NASLIBS Conference, held during SciX in Providence, RI, in September 2015. This topic was selected in view of the numerous recent overall review papers that have successfully given a broad view of the current understanding of laser-material interactions and plasma development and have also discussed the wide landscape of analytical applications of LIBS. This paper is divided into sections that focus on a few of the many applications under development in the LIBS community. We provide a summary of updates to calibration-free LIBS (CF-LIBS) and associated developments using plasma characteristics to improve quantification in LIBS output, both in a dedicated section and as applications are discussed. We have also described the most recent publications studying the sources, generation, and use of molecular features in LIBS, including those naturally present in the spectra of organic materials, and those induced with the addition of salts to enable the measurement of halogens, not typically present in LIBS signals. In terms of development of applications of LIBS, we focused on the use of LIBS for indirect measurements such as pH and degree of humification in soil and heating value in coal. We also reviewed the extant literature on LIBS analysis of agricultural materials, coal, minerals, and metals. Finally, we discuss the nascent developments of spatially heterodyne spectroscopy, a method that seeks to circumnavigate a serious drawback of most spectrometers - very small optical throughput - through the use of interferometers.

  10. Single shot thermometry using laser induced thermal grating

    Science.gov (United States)

    Qu, Pubo; Guan, Xiaowei; Zhang, Zhenrong; Wang, Sheng; Li, Guohua; Ye, Jingfeng; Hu, Zhiyun

    2015-05-01

    With the concern of environmental protection and reducing the fossil fuel consumption, combustion processes need to be more efficient and less contaminable. Therefore, the ability to obtain important thermophysical parameters is crucial to combustion research and combustor design. Traditional surveying techniques were difficult to apply in a confined space, especially the physically intrusions of detectors can alter the combustion processes. Laser-based diagnostic techniques, like CARS, SVRS, PLIF and TDLAS, allow the in situ, non-intrusive, spatially and temporally resolved measurements of combustion parameters in hostile environments. We report here a new non-intrusive optical diagnostic technique, based on laser-induced thermal grating. Thermal gratings generated in NO2/N2 binary mixtures, arise from the nonlinear interaction between the medium and the light radiation from the interference of two pulsed, frequency-doubled Nd:YAG lasers (532 nm). This leads to the formation of a dynamic grating through the resonant absorption and the subsequent collisional relaxation. By the temporally resolved detection of a continuous wave, frequency-doubled Nd:YVO4 probe laser beam (671 nm) diffracted by LITG. The temporal behavior of the signal is a function of the local temperature and other properties of gas, various parameters of the target gas can be extracted by analyzing the signal. The accurate singleshot temperature measurements were carried out at different test conditions using a stainless steel pressurized cell, data averaged on 100 laser shots were compared with simultaneously recorded thermocouple data, and the results were consistent with each other. The LITG signal is shown to grow with increasing the gas pressure and is spatially coherent, which makes the LITG thermometry technique a promising candidate in high pressure environments.

  11. Characterization Of High Explosives Detonations Via Laser-Induced Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Villa-Aleman, E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-08

    One objective of the Department of Energy’s National Security Administration is to develop technologies that can help the United States government to detect foreign nuclear weapons development activities. The realm of high explosive (HE) experiments is one of the key areas to assess the nuclear ambitions of a country. SRNL has participated in the collection of particulates from HE experiments and characterized the material with the purpose to correlate particulate matter with HE. Since these field campaigns are expensive, on-demand simulated laboratory-scale explosion experiments are needed to further our knowledge of the chemistry and particle formation in the process. Our goal is to develop an experimental test bed in the laboratory to test measurement concepts and correlate particle formation processes with the observables from the detonation fireball. The final objective is to use this knowledge to tailor our experimental setups in future field campaigns. The test bed uses pulsed laser-induced plasmas to simulate micro-explosions, with the intent to study the temporal behavior of the fireball observed in field tests. During FY15, a plan was prepared and executed which assembled two laser ablation systems, procured materials for study, and tested a Step-Scan Fourier Transform Infrared Spectrometer (SS-FTIR). Designs for a shadowgraph system for shock wave analysis, design for a micro-particulate collector from ablated pulse were accomplished. A novel spectroscopic system was conceived and a prototype system built for acquisition of spectral/temporal characterization of a high speed event such as from a high explosive detonation. Experiments and analyses will continue into FY16.

  12. Independent component analysis classification of laser induced breakdown spectroscopy spectra

    Energy Technology Data Exchange (ETDEWEB)

    Forni, Olivier, E-mail: olivier.forni@irap.omp.eu [Université de Toulouse, UPS-OMP, Institut de Recherche en Astrophysiqe et Planétologie, Toulouse (France); CNRS, IRAP, 9, av. Colonel Roche, BP 44346, F-31028 Cedex 4, Toulouse (France); Maurice, Sylvestre, E-mail: sylvestre.maurice@irap.omp.eu [Université de Toulouse, UPS-OMP, Institut de Recherche en Astrophysiqe et Planétologie, Toulouse (France); CNRS, IRAP, 9, av. Colonel Roche, BP 44346, F-31028 Cedex 4, Toulouse (France); Gasnault, Olivier, E-mail: olivier.gasnault@irap.omp.eu [Université de Toulouse, UPS-OMP, Institut de Recherche en Astrophysiqe et Planétologie, Toulouse (France); CNRS, IRAP, 9, av. Colonel Roche, BP 44346, F-31028 Cedex 4, Toulouse (France); Wiens, Roger C., E-mail: rwiens@lanl.gov [Space Remote Sensing, Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Cousin, Agnès, E-mail: acousin@lanl.gov [Université de Toulouse, UPS-OMP, Institut de Recherche en Astrophysiqe et Planétologie, Toulouse (France); CNRS, IRAP, 9, av. Colonel Roche, BP 44346, F-31028 Cedex 4, Toulouse (France); Chemical Division, Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Clegg, Samuel M., E-mail: sclegg@lanl.gov [Chemical Division, Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Sirven, Jean-Baptiste, E-mail: jean-baptiste.sirven@cea.f [CEA Saclay, DEN/DPC/SCP, 91191 Cedex, Gif sur Yvette (France); Lasue, Jérémie, E-mail: jeremie.lasue@irap.omp.eu [Université de Toulouse, UPS-OMP, Institut de Recherche en Astrophysiqe et Planétologie, Toulouse (France); CNRS, IRAP, 9, av. Colonel Roche, BP 44346, F-31028 Cedex 4, Toulouse (France)

    2013-08-01

    The ChemCam instrument on board Mars Science Laboratory (MSL) rover uses the laser-induced breakdown spectroscopy (LIBS) technique to remotely analyze Martian rocks. It retrieves spectra up to a distance of seven meters to quantify and to quantitatively analyze the sampled rocks. Like any field application, on-site measurements by LIBS are altered by diverse matrix effects which induce signal variations that are specific to the nature of the sample. Qualitative aspects remain to be studied, particularly LIBS sample identification to determine which samples are of interest for further analysis by ChemCam and other rover instruments. This can be performed with the help of different chemometric methods that model the spectra variance in order to identify a the rock from its spectrum. In this paper we test independent components analysis (ICA) rock classification by remote LIBS. We show that using measures of distance in ICA space, namely the Manhattan and the Mahalanobis distance, we can efficiently classify spectra of an unknown rock. The Mahalanobis distance gives overall better performances and is easier to manage than the Manhattan distance for which the determination of the cut-off distance is not easy. However these two techniques are complementary and their analytical performances will improve with time during MSL operations as the quantity of available Martian spectra will grow. The analysis accuracy and performances will benefit from a combination of the two approaches. - Highlights: • We use a novel independent component analysis method to classify LIBS spectra. • We demonstrate the usefulness of ICA. • We report the performances of the ICA classification. • We compare it to other classical classification schemes.

  13. Lanthanide-based laser-induced phosphorescence for spray diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Voort, D. D. van der, E-mail: d.d.v.d.voort@tue.nl; Water, W. van de; Kunnen, R. P. J.; Clercx, H. J. H.; Heijst, G. J. F. van [Applied Physics Department, Eindhoven University of Technology, 5612 AZ Eindhoven (Netherlands); Maes, N. C. J.; Sweep, A. M.; Dam, N. J. [Mechanical Engineering Department, Eindhoven University of Technology, 5612 AZ Eindhoven (Netherlands); Lamberts, T. [Institute of Theoretical Chemistry, University of Stuttgart, D-70569 Stuttgart (Germany)

    2016-03-15

    Laser-induced phosphorescence (LIP) is a relatively recent and versatile development for studying flow dynamics. This work investigates certain lanthanide-based molecular complexes for their use in LIP for high-speed sprays. Lanthanide complexes in solutions have been shown to possess long phosphorescence lifetimes (∼1-2 ms) and to emit light in the visible wavelength range. In particular, europium and terbium complexes are investigated using fluorescence/phosphorescence spectrometry, showing that europium-thenoyltrifluoracetone-trioctylphosphineoxide (Eu-TTA-TOPO) can be easily and efficiently excited using a standard frequency-tripled Nd:YAG laser. The emitted spectrum, with maximum intensity at a wavelength of 614 nm, is shown not to vary strongly with temperature (293-383 K). The decay constant of the phosphorescence, while independent of ambient pressure, decreases by approximately 12 μs/K between 323 and 373 K, with the base level of the decay constant dependent on the used solvent. The complex does not luminesce in the gas or solid state, meaning only the liquid phase is visualized, even in an evaporating spray. By using an internally excited spray containing the phosphorescent complex, the effect of vaporization is shown through the decrease in measured intensity over the length of the spray, together with droplet size measurements using interferometric particle imaging. This study shows that LIP, using the Eu-TTA-TOPO complex, can be used with different solvents, including diesel surrogates. Furthermore, it can be easily handled and used in sprays to investigate spray breakup and evaporation.

  14. Laser-induced growth of nanocrystals embedded in porous materials

    Science.gov (United States)

    Capoen, Bruno; Chahadih, Abdallah; El Hamzaoui, Hicham; Cristini, Odile; Bouazaoui, Mohamed

    2013-06-01

    Space localization of the linear and nonlinear optical properties in a transparent medium at the submicron scale is still a challenge to yield the future generation of photonic devices. Laser irradiation techniques have always been thought to structure the matter at the nanometer scale, but combining them with doping methods made it possible to generate local growth of several types of nanocrystals in different kinds of silicate matrices. This paper summarizes the most recent works developed in our group, where the investigated nanoparticles are either made of metal (gold) or chalcogenide semiconductors (CdS, PbS), grown in precursor-impregnated porous xerogels under different laser irradiations. This review is associated to new results on silver nanocrystals in the same kind of matrices. It is shown that, depending on the employed laser, the particles can be formed near the sample surface or deep inside the silica matrix. Photothermal and/or photochemical mechanisms may be invoked to explain the nanoparticle growth, depending on the laser, precursor, and matrix. One striking result is that metal salt reduction, necessary to the production of the corresponding nanoparticles, can efficiently occur due to the thermal wrenching of electrons from the matrix itself or due to multiphoton absorption of the laser light by a reducer additive in femtosecond regime. Very localized semiconductor quantum dots could also be generated using ultrashort pulses, but while PbS nanoparticles grow faster than CdS particles due to one-photon absorption, this better efficiency is counterbalanced by a sensitivity to oxidation. In most cases where the reaction efficiency is high, particles larger than the pores have been obtained, showing that a fast diffusion of the species through the interconnected porosity can modify the matrix itself. Based on our experience in these techniques, we compare several examples of laser-induced nanocrystal growth in porous silica xerogels, which allows

  15. Laser-induced selective copper plating of polypropylene surface

    Science.gov (United States)

    Ratautas, K.; Gedvilas, M.; Stankevičiene, I.; JagminienÄ--, A.; Norkus, E.; Li Pira, N.; Sinopoli, S.; Emanuele, U.; Račiukaitis, G.

    2016-03-01

    Laser writing for selective plating of electro-conductive lines for electronics has several significant advantages, compared to conventional printed circuit board technology. Firstly, this method is faster and cheaper at the prototyping stage. Secondly, material consumption is reduced, because it works selectively. However, the biggest merit of this method is potentiality to produce moulded interconnect device, enabling to create electronics on complex 3D surfaces, thus saving space, materials and cost of production. There are two basic techniques of laser writing for selective plating on plastics: the laser-induced selective activation (LISA) and laser direct structuring (LDS). In the LISA method, pure plastics without any dopant (filler) can be used. In the LDS method, special fillers are mixed in the polymer matrix. These fillers are activated during laser writing process, and, in the next processing step, the laser modified area can be selectively plated with metals. In this work, both methods of the laser writing for the selective plating of polymers were investigated and compared. For LDS approach, new material: polypropylene with carbon-based additives was tested using picosecond and nanosecond laser pulses. Different laser processing parameters (laser pulse energy, scanning speed, the number of scans, pulse durations, wavelength and overlapping of scanned lines) were applied in order to find out the optimal regime of activation. Areal selectivity tests showed a high plating resolution. The narrowest width of a copper-plated line was less than 23 μm. Finally, our material was applied to the prototype of the electronic circuit board on a 2D surface.

  16. Spectrally resolved laser-induced fluorescence for bioaerosols standoff detection

    Science.gov (United States)

    Buteau, Sylvie; Stadnyk, Laurie; Rowsell, Susan; Simard, Jean-Robert; Ho, Jim; Déry, Bernard; McFee, John

    2007-09-01

    An efficient standoff biological warfare detection capability could become an important asset for both defence and security communities based on the increasing biological threat and the limits of the presently existing protection systems. Defence R&D Canada (DRDC) has developed, by the end of the 90s, a standoff bioaerosol sensor prototype based on intensified range-gated spectrometric detection of Laser Induced Fluorescence (LIF). This LIDAR system named SINBAHD monitors the spectrally resolved LIF originating from inelastic interactions with bioaerosols present in atmospheric cells customizable in size and in range. SINBAHD has demonstrated the capability of near real-time detection and classification of bioaerosolized threats at multi-kilometre ranges. In spring 2005, DRDC has initiated the BioSense demonstration project, which combines the SINBAHD technology with a geo-referenced Near InfraRed (NIR) LIDAR cloud mapper. SINBAHD is now being used to acquire more signatures to add in the spectral library and also to optimize and test the new BioSense algorithm strategy. In September 2006, SINBAHD has participated in a two-week trial held at DRDC-Suffield where different open-air wet releases of live and killed bioagent simulants, growth media and obscurants were performed. An autoclave killing procedure was performed on two biological materials (Bacillus subtilis var globigii or BG, and Bacillus thuringiensis or Bt) before being aerosolized, disseminated and spectrally characterized with SINBAHD. The obtained results showed no significant impact of this killing process on their normalised spectral signature in comparison with their live counterparts. Correlation between the detection signals from SINBAHD, an array of slit samplers and a FLuorescent Aerosol Particle Sensor (C-FLAPS) was obtained and SINBAHD's sensitivity could then be estimated. At the 2006 trial, a detection limit of a few tens of Agent Containing Particles per Liter of Air (ACPLA) was obtained

  17. About Dental Amalgam Fillings

    Science.gov (United States)

    ... and Medical Procedures Dental Devices Dental Amalgam About Dental Amalgam Fillings Share Tweet Linkedin Pin it More ... should I have my fillings removed? What is dental amalgam? Dental amalgam is a dental filling material ...

  18. Black Holes

    Science.gov (United States)

    Luminet, Jean-Pierre

    1992-09-01

    Foreword to the French edition; Foreword to the English edition; Acknowledgements; Part I. Gravitation and Light: 1. First fruits; 2. Relativity; 3. Curved space-time; Part II. Exquisite Corpses: 4. Chronicle of the twilight years; 5. Ashes and diamonds; 6. Supernovae; 7. Pulsars; 8. Gravitation triumphant; Part III. Light Assassinated: 9. The far horizon; 10. Illuminations; 11. A descent into the maelstrom; 12. Map games; 13. The black hole machine; 14. The quantum black hole; Part IV. Light Regained: 15. Primordial black holes; 16. The zoo of X-ray stars; 17. Giant black holes; 18. Gravitational light; 19. The black hole Universe; Appendices; Bibliography; Name index; Subject index.

  19. Optimization of an Image-Guided Laser-Induced Choroidal Neovascularization Model in Mice.

    Directory of Open Access Journals (Sweden)

    Yan Gong

    Full Text Available The mouse model of laser-induced choroidal neovascularization (CNV has been used in studies of the exudative form of age-related macular degeneration using both the conventional slit lamp and a new image-guided laser system. A standardized protocol is needed for consistent results using this model, which has been lacking. We optimized details of laser-induced CNV using the image-guided laser photocoagulation system. Four lesions with similar size were consistently applied per eye at approximately double the disc diameter away from the optic nerve, using different laser power levels, and mice of various ages and genders. After 7 days, the mice were sacrificed and retinal pigment epithelium/choroid/sclera was flat-mounted, stained with Isolectin B4, and imaged. Quantification of the area of the laser-induced lesions was performed using an established and constant threshold. Exclusion criteria are described that were necessary for reliable data analysis of the laser-induced CNV lesions. The CNV lesion area was proportional to the laser power levels. Mice at 12-16 weeks of age developed more severe CNV than those at 6-8 weeks of age, and the gender difference was only significant in mice at 12-16 weeks of age, but not in those at 6-8 weeks of age. Dietary intake of omega-3 long-chain polyunsaturated fatty acid reduced laser-induced CNV in mice. Taken together, laser-induced CNV lesions can be easily and consistently applied using the image-guided laser platform. Mice at 6-8 weeks of age are ideal for the laser-induced CNV model.

  20. Model system for investigating laser-induced subcellular microeffects

    Science.gov (United States)

    Huettmann, Gereon; Serbin, Jesper; Radt, Benno; Lange, Bjoern I.; Birngruber, Reginald

    2001-07-01

    Background: Laser induced protein denaturation is of fundamental interest for understanding the mechanisms of laser tissue interaction. Conjugates of nanoabsorbers coupled to proteins are presented as a model system for investigating ultrafast protein denaturation. Irradiation of the conjugates using repetitive picosecond laser pulses, which are only absorbed by the nanoabsorbers, could result in effects with a spatial confinement of less than 100 nm. Materials and Methods: Experiments were done with bovine intestinal alkaline phosphates (aP) coupled to 15 nm colloidal gold. This complex was irradiated at 527 nm wavelength and 35 ps pulse width with a varying number of pulses ranging form one up to 104. The radiant exposure per pulse was varied form 2 mJ/cm2 to 50 mJ/cm2. Denaturation was detected as a loss of protein function with the help of the fluorescence substrate 4MUP. Results and discussion: Irradiation did result in a steady decrease of the aP activity with increasing radiant exposures and increasing number of pulses. A maximal inactivation of 80% was reached with 104 pulses and 50 mJ/cm2 per pulse. The temperature in the particles and the surrounding water was calculated using Mie's formulas for the absorption of the nanometer gold particles and ana analytical solution of the equations for heat diffusion. With 50 mJ/cm2, the particles are heated above the melting point of gold. Since the temperature calculations strongly depend on changes in the state of matter of the particles and water, a very sophisticated thermal model is necessary to calculate exact temperatures. It is difficult to identify one of the possible mechanisms, thermal denaturation, photochemical denaturation or formation of micro bubbles from the dependance of the inactivation on pulse energy and number of applied pulses. Therefore, experiments are needed to further elucidate the damage mechanisms. In conclusion, denaturing proteins irreversibly via nanoabsorbers using picosecond laser

  1. Pulsed laser-induced liquid jet: evolution from shock/bubble interaction to neurosurgical application

    Science.gov (United States)

    Nakagawa, A.; Kumabe, T.; Ogawa, Y.; Hirano, T.; Kawaguchi, T.; Ohtani, K.; Nakano, T.; Sato, C.; Yamada, M.; Washio, T.; Arafune, T.; Teppei, T.; Atsushi, K.; Satomi, S.; Takayama, K.; Tominaga, T.

    2016-11-01

    The high-speed liquid (water) jet has distinctive characteristics in surgical applications, such as tissue dissection without thermal damage and small blood vessel preservation, that make it advantageous over more conventional instruments. The continuous pressurized jet has been used since the first medical application of water jets to liver surgery in the 1980s, but exhibited drawbacks partly related to the excess water supply required and unsuitability for application to microsurgical instruments intended for deep, narrow lesions (endoscopic instrumentation and catheters) due to limitations in miniaturization of the device. To solve these issues, we initiated work on the pulsed micro-liquid jet. The idea of the pulsed micro-liquid jet originated from the observation of tissue damage by shock/bubble interactions during extracorporeal shock wave lithotripsy and evolved into experimental application for recanalization of cerebral embolisms in the 1990s. The original method of generating the liquid jet was based on air bubble formation and microexplosives as the shock wave source, and as such could not be applied clinically. The air bubble was replaced by a holmium:yttrium-aluminum-garnet (Ho:YAG) laser-induced bubble. Finally, the system was simplified and the liquid jet was generated via irradiation from the Ho:YAG laser within a liquid-filled tubular structure. A series of investigations revealed that this pulsed laser-induced liquid jet (LILJ) system has equivalent dissection and blood vessel preservation characteristics, but the amount of liquid usage has been reduced to less than 2 μ l per shot and can easily be incorporated into microsurgical, endoscopic, and catheter devices. As a first step in human clinical studies, we have applied the LILJ system for the treatment of skull base tumors through the transsphenoidal approach in 9 patients (7 pituitary adenomas and 2 chordomas), supratentorial glioma (all high grade glioma) in 8 patients, including one with

  2. Pulsed laser-induced liquid jet: evolution from shock/bubble interaction to neurosurgical application

    Science.gov (United States)

    Nakagawa, A.; Kumabe, T.; Ogawa, Y.; Hirano, T.; Kawaguchi, T.; Ohtani, K.; Nakano, T.; Sato, C.; Yamada, M.; Washio, T.; Arafune, T.; Teppei, T.; Atsushi, K.; Satomi, S.; Takayama, K.; Tominaga, T.

    2017-01-01

    The high-speed liquid (water) jet has distinctive characteristics in surgical applications, such as tissue dissection without thermal damage and small blood vessel preservation, that make it advantageous over more conventional instruments. The continuous pressurized jet has been used since the first medical application of water jets to liver surgery in the 1980s, but exhibited drawbacks partly related to the excess water supply required and unsuitability for application to microsurgical instruments intended for deep, narrow lesions (endoscopic instrumentation and catheters) due to limitations in miniaturization of the device. To solve these issues, we initiated work on the pulsed micro-liquid jet. The idea of the pulsed micro-liquid jet originated from the observation of tissue damage by shock/bubble interactions during extracorporeal shock wave lithotripsy and evolved into experimental application for recanalization of cerebral embolisms in the 1990s. The original method of generating the liquid jet was based on air bubble formation and microexplosives as the shock wave source, and as such could not be applied clinically. The air bubble was replaced by a holmium:yttrium-aluminum-garnet (Ho:YAG) laser-induced bubble. Finally, the system was simplified and the liquid jet was generated via irradiation from the Ho:YAG laser within a liquid-filled tubular structure. A series of investigations revealed that this pulsed laser-induced liquid jet (LILJ) system has equivalent dissection and blood vessel preservation characteristics, but the amount of liquid usage has been reduced to less than 2 μ l per shot and can easily be incorporated into microsurgical, endoscopic, and catheter devices. As a first step in human clinical studies, we have applied the LILJ system for the treatment of skull base tumors through the transsphenoidal approach in 9 patients (7 pituitary adenomas and 2 chordomas), supratentorial glioma (all high grade glioma) in 8 patients, including one with

  3. Investigation of Normalization Methods using Plasma Parameters for Laser Induced Breakdown Spectroscopy (LIBS) under simulated Martian Conditions

    OpenAIRE

    Vogt, David; Schröder, Susanne; Hübers, H.-W.

    2017-01-01

    Laser Induced Breakdown Spectroscopy data need to be normalized, especially in the field of planetary exploration We investigated plasma parameters as temperature and electron density for this purpose.

  4. Borehole cylindrical noise during hole-surface and hole-hole resistivity measurements

    Science.gov (United States)

    Osiensky, James L.; Nimmer, Robin; Binley, Andrew M.

    2004-04-01

    Drilled boreholes generally are the only feasible means to access the subsurface for the emplacement of downhole electrodes for most hole-hole and hole-surface resistivity experiments. However, the very existence of the borehole itself creates the potential for significant noise due to the inevitable conductivity contrast that develops between the borehole walls and the formation. Borehole cylindrical noise develops whenever a current source is placed in a drilled borehole. Borehole geometries may range from nearly perfect cylinders to highly, irregular, rugose holes in consolidated rock, to relatively minor, collapsed, disturbed zones in caving sediments. Boreholes in non-caving formations generally are filled with artificial, conductive materials to afford crucial, electrical continuity between downhole electrodes and the borehole walls. Filled boreholes form cylindrically shaped heterogeneities that create significant noise due to preferential current flow up and down the conductive columns. Selected conditions are simulated with a finite difference model to illustrate the significance of borehole cylindrical noise on hole-hole and hole-surface mise-à-la-masse electrical potentials near a current electrode. Mise-à-la-masse electrical potentials measured during a field tracer experiment also are presented. These measurements are used to illustrate significant errors may develop in the interpretation of apparent resistivity estimates out to a distance of several meters from the current source if borehole cylindrical noise is not recognized and accounted for in the analysis of electrical potential data.

  5. Laser-induced forward transfer of polymer light-emitting diode pixels with increased charge injection.

    Science.gov (United States)

    Shaw-Stewart, James; Lippert, Thomas; Nagel, Matthias; Nüesch, Frank; Wokaun, Alexander

    2011-02-01

    Laser-induced forward transfer (LIFT) has been used to print 0.6 mm × 0.5 mm polymer light-emitting diode (PLED) pixels with poly[2-methoxy, 5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV) as the light-emitting polymer. The donor substrate used in the LIFT process is covered by a sacrificial triazene polymer (TP) release layer on top of which the aluminium cathode and functional MEH-PPV layers are deposited. To enhance electron injection into the MEH-PPV layer, a thin poly(ethylene oxide) (PEO) layer on the Al cathode or a blend of MEH-PPV and PEO was used. These donor substrates have been transferred onto both plain indium tin oxide (ITO) and bilayer ITO/PEDOT:PSS (poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) blend) receiver substrates to create the PLED pixels. For comparison, devices were fabricated in a conventional manner on ITO substrates coated with a PEDOT:PSS hole-transporting layer. Compared to multilayer devices without PEO, devices with ITO/PEDOT:PSS/MEH-PPV:PEO blend/Al architecture show a 100 fold increase of luminous efficiency (LE) reaching a maximum of 0.45 cd/A for the blend at a brightness of 400 cd/m(2). A similar increase is obtained for the polymer light-emitting diode (PLED) pixels deposited by the LIFT process, although the maximum luminous efficiency only reaches 0.05 cd/A for MEH-PPV:PEO blend, which we have attributed to the fact that LIFT transfer was carried out in an ambient atmosphere. For all devices, we confirm a strong increase in device performance and stability when using a PEDOT:PSS film on the ITO anode. For PLEDs produced by LIFT, we show that a 25 nm thick PEDOT:PSS layer on the ITO receiver substrate considerably reduces the laser fluence required for pixel transfer from 250 mJ/cm(2) without the layer to only 80 mJ/cm(2) with the layer.

  6. Laser-induced THz magnetization precession for a tetragonal Heusler-like nearly compensated ferrimagnet

    Energy Technology Data Exchange (ETDEWEB)

    Mizukami, S., E-mail: mizukami@wpi-aimr.tohoku.ac.jp; Sugihara, A.; Suzuki, K. Z.; Miyazaki, T. [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Iihama, S.; Sasaki, Y. [Department of Applied Physics, Tohoku University, Sendai 980-8579 (Japan)

    2016-01-04

    Laser-induced magnetization precessional dynamics was investigated in epitaxial films of Mn{sub 3}Ge, which is a tetragonal Heusler-like nearly compensated ferrimagnet. The ferromagnetic resonance (FMR) mode was observed, the precession frequency for which exceeded 0.5 THz and originated from the large magnetic anisotropy field of approximately 200 kOe for this ferrimagnet. The effective damping constant was approximately 0.03. The corresponding effective Landau-Lifshitz constant is approximately 60 Mrad/s and is comparable with those of the similar Mn-Ga materials. The physical mechanisms for the Gilbert damping and for the laser-induced excitation of the FMR mode were also discussed in terms of the spin-orbit-induced damping and the laser-induced ultrafast modulation of the magnetic anisotropy, respectively.

  7. Analysis of plutonium oxide surrogate residue using laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zheng Hongbo [Department of Applied Physics, College of Science, Nanjing University of Technology, Nanjing (China); Yueh, F.Y.; Miller, Tracy [Institute for Clean Energy Technology (ICET), Mississippi State University, Starkville, MS 39759-7704 (United States); Singh, Jagdish P. [Institute for Clean Energy Technology (ICET), Mississippi State University, Starkville, MS 39759-7704 (United States)], E-mail: singh@icet.msstate.edu; Zeigler, Kristine E.; Marra, James C. [Savannah River National Laboratory (SRNL), Aiken, SC 29808 (United States)

    2008-09-15

    Laser-induced breakdown spectroscopy was used to determine the elemental composition of a CeO{sub 2} composite powder for process control verification during lanthanide borosilicate glass fabrication. Cerium oxide is used as a surrogate for plutonium oxide, which along with other canister contents will be combined with frit to make glass. Laser-induced breakdown spectroscopy data for the composition of the CeO{sub 2} batch containing concentrations of Ce, Cr, Si, Fe, Ta, Ni, Zn, Al Mg, Gd, and W were quantitatively determined from laser-induced breakdown spectroscopy spectra of both pellet and powder samples. The results of both forms were compared and it was determined that the pellet data gave slightly better precision than the powder sample.

  8. Laser-induced THz magnetization precession for a tetragonal Heusler-like nearly compensated ferrimagnet

    Science.gov (United States)

    Mizukami, S.; Sugihara, A.; Iihama, S.; Sasaki, Y.; Suzuki, K. Z.; Miyazaki, T.

    2016-01-01

    Laser-induced magnetization precessional dynamics was investigated in epitaxial films of Mn3Ge, which is a tetragonal Heusler-like nearly compensated ferrimagnet. The ferromagnetic resonance (FMR) mode was observed, the precession frequency for which exceeded 0.5 THz and originated from the large magnetic anisotropy field of approximately 200 kOe for this ferrimagnet. The effective damping constant was approximately 0.03. The corresponding effective Landau-Lifshitz constant is approximately 60 Mrad/s and is comparable with those of the similar Mn-Ga materials. The physical mechanisms for the Gilbert damping and for the laser-induced excitation of the FMR mode were also discussed in terms of the spin-orbit-induced damping and the laser-induced ultrafast modulation of the magnetic anisotropy, respectively.

  9. Laser-induced breakdown spectroscopy detection of heavy metal in water based on graphite conch method

    Science.gov (United States)

    Wang, Chunlong; Liu, Jianguo; Zhao, Nanjing; Shi, Huan; Liu, Lituo; Ma, Mingjun; Zhang, Wei; Chen, Dong; Liu, Jing; Zhang, Yujun; Liu, Wenqing

    2012-10-01

    The laser-induced breakdown spectroscopy emission characteristics of trace heavy metal lead in water is studied based on graphite conch method, with a 1064nm wavelength Nd: YAG laser as excitation source, the echelle spectrometer and ICCD detector are used for spectral separation and high sensitive detection with high resolution and wide spectral range. The delay time 900ns and gate time 1600ns are determined in the experiment. The calibration curve of Pb is plotted based on the different concentration measurement results, and a limit of detection of 0.0138mg / L is obtained for Pb in water. Graphite conch method effectively overcomes the current problems on laser-induced breakdown spectroscopy detection of heavy metal in water. The detection limits and stability are improved. The reference data is provided for further study on the fast measurement of trace heavy metals in water by laser induced breakdown spectroscopy technique.

  10. Laser-induced acoustic desorption (LIAD) mass spectrometry.

    Science.gov (United States)

    Dow, Alex M; Wittrig, Ashley R; Kenttämaa, Hilkka I

    2012-01-01

    Large thermally labile molecules were not amenable to mass spectrometric analysis until the development of atmospheric pressure evaporation/ionization methods, such as electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI), since attempts to evaporate these molecules by heating induces degradation of the sample. While ESI and MALDI are relatively soft desorption/ionization techniques, they are both limited to preferential ionization of acidic and basic analytes. This limitation has been the driving force for the development of other soft desorption/ionization techniques. One such method employs laser-induced acoustic desorption (LIAD) to evaporate neutral sample molecules into mass spectrometers. LIAD utilizes acoustic waves generated by a laser pulse in a thin metal foil. The acoustic waves travel through the foil and cause desorption of neutral molecules that have been deposited on the opposite side of the foil. One of the advantages of LIAD is that it desorbs low-energy molecules that can be ionized by a variety of methods, thus allowing the analysis of large molecules that are not amenable to ESI and MALDI. This review covers the generation of acoustic waves in foils via a laser pulse, the parameters affecting the generation of acoustic waves, possible mechanisms for desorption of neutral molecules, as well as the various uses of LIAD by mass spectrometrists. The conditions used to generate acoustic or stress waves in solid materials consist of three regimes: thermal, ablative, and constrained. Each regime is discussed, in addition to the mechanisms that lead to the ablation of the metal from the foil and generation of acoustic waves for two of the regimes. Previously proposed desorption mechanisms for LIAD are presented along with the flaws associated with some of them. Various experimental parameters, such as the exact characteristics of the laser pulse and foil used, are discussed. The internal and kinetic energy of the neutral

  11. Effects of polarization and absorption on laser induced optical breakdown threshold for skin rejuvenation

    Science.gov (United States)

    Varghese, Babu; Bonito, Valentina; Turco, Simona; Verhagen, Rieko

    2016-03-01

    Laser induced optical breakdown (LIOB) is a non-linear absorption process leading to plasma formation at locations where the threshold irradiance for breakdown is surpassed. In this paper we experimentally demonstrate the influence of polarization and absorption on laser induced breakdown threshold in transparent, absorbing and scattering phantoms made from water suspensions of polystyrene microspheres. We demonstrate that radially polarized light yields a lower irradiance threshold for creating optical breakdown compared to linearly polarized light. We also demonstrate that the thermal initiation pathway used for generating seed electrons results in a lower irradiance threshold compared to multiphoton initiation pathway used for optical breakdown.

  12. Pulse laser induced graphite-to-diamond phase transition: the role of quantum electronic stress

    Science.gov (United States)

    Wang, ZhengFei; Liu, Feng

    2017-02-01

    First-principles calculations show that the pulse laser induced graphite-to-diamond phase transition is related to the lattice stress generated by the excited carriers, termed as "quantum electronic stress (QES)". We found that the excited carriers in graphite generate a large anisotropic QES that increases linearly with the increasing carrier density. Using the QES as a guiding parameter, structural relaxation spontaneously transforms the graphite phase into the diamond phase, as the QES is reduced and minimized. Our results suggest that the concept of QES can be generally applied as a good measure to characterize the pulse laser induced phase transitions, in analogy to pressure induced phase transitions.

  13. Laser-induced synthesis and decay of Tritium under exposure of solid targets in heavy water

    CERN Document Server

    Barmina, E V; Timashev, S F; Shafeev, G A

    2013-01-01

    The processes of laser-assisted synthesis of Tritium nuclei and their laser-induced decay in cold plasma in the vicinity of solid targets (Au, Ti, Se, etc.) immersed into heavy water are experimentally realized at peak laser intensity of 10E10-10E13 Watts per square centimeter. Initial stages of Tritium synthesis and their laser-induced beta-decay are interpreted on the basis of non-elastic interaction of plasma electrons having kinetic energy of 5-10 eV with nuclei of Deuterium and Tritium, respectively.

  14. Online compositional analysis in coal gasification environment using laser-induced plasma technology

    Science.gov (United States)

    Deng, Kung-Li; Wu, Juntao; Wang, Zhe; Lee, Boon; Guida, Renato

    2006-08-01

    Integrated Gasification Combined Cycle (IGCC) power plants have great potential for future clean-coal power generation. Today, the quality of coal is measured by sampling coal using various offline methods, and the syn-gas composition is determined by taking samples downstream of the gasifier and measured by gas chromatograph (GC). Laser induced plasma technology has demonstrated high sensitivity for elementary detection. The capability of free space transmission and focusing of laser beam makes laser induced plasma a unique technology for online compositional analysis in coal gasification environment and optimization control.

  15. Influence of Ambient Temperature on Nanosecond and Picosecond Laser-Induced Bulk Damage of Fused Silica

    Directory of Open Access Journals (Sweden)

    L. Yang

    2014-01-01

    Full Text Available The nanosecond (ns and picosecond (ps pulsed laser-induced damage behaviors of fused silica under cryogenic and room temperature have been investigated. The laser-induced damage threshold (LIDT and damage probability are used to understand the damage behavior at different ambient temperatures. The results show that the LIDTs for both ns and ps slightly increased at cryogenic temperature compared to that at room temperature. Meanwhile, the damage probability has an inverse trend; that is, the damage probability at low temperature is smaller than that at room temperature. A theoretical model based on heated crystal lattice is well consistent with the experimental results.

  16. Non-gated laser-induced breakdown spectroscopy in bulk water by position-selective detection

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Ye; Xue, Boyang; Song, Jiaojian; Lu, Yuan; Zheng, Ronger, E-mail: rzheng@ouc.edu.cn [Optics and Optoelectronics Laboratory, Ocean University of China, Qingdao 266100 (China)

    2015-09-14

    Temporal and spatial evolutions of the laser-induced plasma in bulk water are investigated using fast imaging and emission spectroscopic techniques. By tightly focusing a single-pulse nanosecond Nd: YAG laser beam into the bulk water, we generate a strongly expanded plasma with high reproducibility. Such a strong expanding plasma enables us to obtain well-resolved spectral lines by means of position-selective detection; hence, the time-gated detector becomes abdicable. The present results suggest not only a possible non-gated approach for underwater laser-induced breakdown spectroscopy but also give an insight into the plasma generation and expansion in bulk water.

  17. Optimally enhanced optical emission in laser-induced air plasma by femtosecond double-pulse

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Anmin [Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012 (China); Institute of Theoretical Chemistry, State Key Laboratory of Theoretical and Computational Chemistry, Jilin University, Changchun 130012 (China); Li, Suyu; Li, Shuchang; Jiang, Yuanfei; Ding, Dajun [Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012 (China); Shao, Junfeng; Wang, Tingfeng [State Key Laboratory of Laser Interaction with Matter, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); Huang, Xuri [Institute of Theoretical Chemistry, State Key Laboratory of Theoretical and Computational Chemistry, Jilin University, Changchun 130012 (China); Jin, Mingxing [Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012 (China); State Key Laboratory of Laser Interaction with Matter, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China)

    2013-10-15

    In laser-induced breakdown spectroscopy, a femtosecond double-pulse laser was used to induce air plasma. The plasma spectroscopy was observed to lead to significant increase of the intensity and reproducibility of the optical emission signal compared to femtosecond single-pulse laser. In particular, the optical emission intensity can be optimized by adjusting the delay time of femtosecond double-pulse. An appropriate pulse-to-pulse delay was selected, that was typically about 50 ps. This effect can be especially advantageous in the context of femtosecond laser-induced breakdown spectroscopy, plasma channel, and so on.

  18. Laser-induced lensing effects in solid-state optical refrigerators

    Science.gov (United States)

    Silva, J. R.; Andrade, L. H. C.; Lima, S. M.; Hehlen, M. P.; Guyot, Y.; Medina, A. N.; Malacarne, L. C.; Baesso, M. L.; Astrath, N. G. C.

    2013-04-01

    Laser-induced thermal and population lensing effects in solid-state optical refrigerator materials are quantitatively evaluated. Time-resolved lensing transients in Yb3+ doped ZBLAN and aluminosilicate glasses are measured, and the model decouples thermal and population lensing effects. The analysis yields the net power density, the cooling efficiency, and important photo-physical parameters. The respective values are in good agreement with previously reported parameters for ZBLAN glass. Aluminosilicate glass is found to be a promising optical refrigerator material. We show that the measurement of laser-induced lensing is a valuable tool that can advance the characterization and optimization of materials for cryogenic optical refrigerators.

  19. Clinical detection studies of Barrett's metaplasia and oesophageal adenocarcinoma by means of laser-induced fluorescence

    Science.gov (United States)

    Nilsson, Annika M.; von Holstein, Christer S.; Andersson-Engels, Stefan; Willen, Roger; Walther, Bruno; Svanberg, Katarina

    1995-12-01

    Five patients with Barrett's metaplastic epithelium were investigated by means of laser- induced fluorescence after low-dose i.v. injection (0.35 mg/kg b.w.) of PhotofrinR in connection with endoscopy procedures. The excitation wavelength was 405 nm. Recorded fluorescence spectra were evaluated by forming ratios with the photosensitizer fluorescence as numerator and the autofluorescence as denominator. Two patients had no evidence of malignancy and their fluorescence ratios were consequently rather small, whereas the other three patients had adenocarcinoma and showed considerably higher ratios. The results indicate that laser-induced fluorescence can be used as an aid in detecting malignant transformations in Barrett's metaplasia.

  20. InP-based two-dimensional photonic crystals filled with polymers

    NARCIS (Netherlands)

    Van der Heijden, R.; Carlström, C.F.; Snijders, J.A.P.; Van der Heijden, R.W.; Karouta, F.; Nötzel, R.; Salemink, H.W.M.; Kjellander, B.K.C.; Bastiaansen, C.W.M.; Broer, D.J.; Van der Drift, E.

    2006-01-01

    Polymer filling of the air holes of indium-phosphide-based two-dimensional photonic crystals is reported. After infiltration of the holes with a liquid monomer and solidification of the infill in situ by thermal polymerization, complete filling is proven using scanning electron microscopy. Optical t

  1. Getting a prescription filled

    Science.gov (United States)

    ... are located inside of a grocery or large "chain" store. It is best to fill all prescriptions ... be used for long-term medicines and medical supplies. The website should have clear directions for filling ...

  2. The spatial emergence of laser-induced periodic surface structures under lateral displacement irradiation conditions

    NARCIS (Netherlands)

    Eichstädt, J.

    2015-01-01

    Recently, laser-induced periodic surface structures, abbreviated LIPSS, gained interest, because potential applications are seen in the field of surface functionalisation. The feasibility to produce LIPSS and the potential to influence surface functionality have been shown. But so far, the

  3. Effects of thermo-plasmonics on laser-induced backside wet etching of silicate glass

    Science.gov (United States)

    Tsvetkov, M. Yu; Yusupov, V. I.; Minaev, N. V.; Timashev, P. S.; Golant, K. M.; Bagratashvili, V. N.

    2016-10-01

    The thermo-plasmonic effect (heat deposition via absorption of laser light by metal nanoparticles) is applied to substantially enhance the effectiveness and controllability of the microstructure formation by laser-induced backside wet etching (LIBWE). Experiments were carried out with silicate glass plates using a pulsed 527 nm wavelength laser and an aqueous solution of AgNO3 as a precursor of the Ag nanoparticles. Mechanisms of such thermo-plasmonic LIBWE (TP-LIBWE) versions are considered. They involve: laser-induced photo-thermal reducing of silver (Ag) and self-assembling of Ag nanoparticles in water and the water/glass interface; fast laser-induced overheating of a water and glass surface through the thermo-plasmonic effect; formation of highly reactive supercritical water that causes glass etching and crater formation; generation of steam-gas bubbles in a liquid. It is significant that the emergence of the Marangoni convection results in bubble retention in the focal point at the interface and the accumulation of nanoparticles on the surface of the laser-induced crater, as this facilitates the movement of the bubbles with captured Ag particles from the fluid volume in the crater region, and accelerates the formation of the area of strong ‘surface absorption’ of laser energy. All these mechanisms provide a highly efficient and reproducible process for laser microstructure formation on the surface of glass using a novel TP-LIBWE technique.

  4. Characterization of metal sprays created by a picosecond Laser-Induced Forward Transfer (LIFT) process

    NARCIS (Netherlands)

    Pohl, R.; Römer, G.R.B.E.; Hoppenbrouwers, M.B.; Huis in 't Veld, A.J.

    2012-01-01

    A new method to analyze and quantify results obtained with the Laser-Induced Forward Transfer (LIFT) process is presented. This experiment based characterization method was designed to investigate the spraying behavior of the LIFT process, that occurs in certain fluence regimes. This method was

  5. Characterization of Metal Sprays Created by a Picosecond Laser-Induced Forward Transfer (LIFT) Process

    NARCIS (Netherlands)

    Pohl, Ralph; Römer, Gerardus Richardus, Bernardus, Engelina; Hoppenbrouwers, M.; Huis in 't Veld, Bert

    2012-01-01

    A new method to analyze and quantify results obtained with the Laser-Induced Forward Transfer (LIFT) process is presented. This experiment based characterization method was designed to investigate the spraying behavior of the LIFT process, that occurs in certain fluence regimes. This method was

  6. Laser induced fluorescence measurements of the mixing of fuel oil with air

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, A.; Bombach, R.; Hubschmid, W.; Kaeppeli, B. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    We report on measurements of the mixing of fuel oil with air at atmospheric pressure in an industrial premixed gas turbine burner. The concentration of the vaporized fuel oil was measured with laser induced fluorescence. We reason that the fuel oil concentration can be considered with good accuracy as proportional to the fluorescence intensity. (author) 6 fig., 3 refs.

  7. Sorbitol as an efficient reducing agent for laser-induced copper deposition

    Science.gov (United States)

    Kochemirovsky, V. A.; Logunov, L. S.; Safonov, S. V.; Tumkin, I. I.; Tver'yanovich, Yu. S.; Menchikov, L. G.

    2012-10-01

    We have pioneered in revealing the fact that sorbitol may be used as an efficient reducing agent in the process of laser-induced copper deposition from solutions; in this case, it is possible to obtain copper lines much higher quality than by using conventional formalin.

  8. Boosting persistence time of laser-induced plasma by electric arc discharge for optical emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Eschlböck-Fuchs, S., E-mail: simon.eschlboeck-fuchs@jku.at [Christian Doppler Laboratory for Laser-Assisted Diagnostics, Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Kolmhofer, P.J.; Bodea, M.A.; Hechenberger, J.G.; Huber, N. [Christian Doppler Laboratory for Laser-Assisted Diagnostics, Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Rössler, R. [voestalpine Stahl GmbH, A-4031 Linz (Austria); Pedarnig, J.D., E-mail: johannes.pedarnig@jku.at [Christian Doppler Laboratory for Laser-Assisted Diagnostics, Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria)

    2015-07-01

    Plasma induced by nanosecond laser ablation is re-excited by a pulsed electric discharge and the parameters and optical emission of the plasma are measured. The discharge is a low-voltage and high-current electric arc that is triggered by the laser-induced plasma and slowly decaying with time. The optical emission of such combined plasma lasts up to several milliseconds which is much longer than without re-excitation (μs range). The emission spectra of re-excited plasma measured on different sample materials show higher line intensities than spectra measured by conventional laser-induced breakdown spectroscopy (LIBS). Moreover, emission lines of fluorine (spectral range 683–691 nm) and sulfur (range 520–550 nm) not detected by conventional LIBS become easily detectable with the combined plasma. The concentration of major components in metallurgical slags, as determined by calibration-free LIBS, agrees very well to the reference data evaluating the spectra taken from re-excited plasma. - Highlights: • Persistence time of laser-induced plasma in air is increased from ~ 10 μs to ~ 1 ms. • Laser-induced plasma triggers an electric arc discharge that boosts the plasma. • The combined laser-arc plasma is in LTE state over very long time (ms range). • CF-LIBS method delivers accurate results evaluating spectra of combined plasma. • Emission from S and F, not detected by LIBS, is detected with combined plasma.

  9. [The Spectral Analysis of Laser-Induced Plasma in Laser Welding with Various Protecting Conditions].

    Science.gov (United States)

    Du, Xiao; Yang, Li-jun; Liu, Tong; Jiao, Jiao; Wang, Hui-chao

    2016-01-01

    The shielding gas plays an important role in the laser welding process and the variation of the protecting conditions has an obvious effect on the welding quality. This paper studied the influence of the change of protecting conditions on the parameters of laser-induced plasma such as electron temperature and electron density during the laser welding process by designing some experiments of reducing the shielding gas flow rate step by step and simulating the adverse conditions possibly occurring in the actual Nd : YAG laser welding process. The laser-induced plasma was detected by a fiber spectrometer to get the spectral data. So the electron temperature of laser-induced plasma was calculated by using the method of relative spectral intensity and the electron density by the Stark Broadening. The results indicated that the variation of protecting conditions had an important effect on the electron temperature and the electron density in the laser welding. When the protecting conditions were changed, the average electron temperature and the average electron density of the laser-induced plasma would change, so did their fluctuation range. When the weld was in a good protecting condition, the electron temperature, the electron density and their fluctuation were all low. Otherwise, the values would be high. These characteristics would have contribution to monitoring the process of laser welding.

  10. Formation of nitric oxide in an industrial burner measured by 2-D laser induced fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, A.; Bombach, R.; Kaeppeli, B. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    We have performed two-dimensional Laser Induced Fluorescence (2-D LIF) measurements of nitric oxide and hydroxyl radical distributions in an industrial burner at atmospheric pressure. The relative 2-D LIF data of NO were set to an absolute scale by calibration with probe sampling combined with gas analysis. (author) 3 figs., 7 refs.

  11. Combined raman/laser-induced breakdown spectrometer: space and non-space applications

    NARCIS (Netherlands)

    Sandtke, M.; Laan, E.C.; Ahlers, B.

    2010-01-01

    TNO has developed the combination of two spectroscopic analysis methods in one instrument. Raman spectroscopy and Laser-induced Breakdown Spectroscopy (LIBS) were brought together for an instrument to be flown on the ExoMars mission from the European Space Agency (ESA) to investigate the Martian (su

  12. Minimally invasive non-thermal laser technology using laser-induced optical breakdown for skin rejuvenation

    NARCIS (Netherlands)

    Habbema, L.; Verhagen, R.; Van Hal, R.; Liu, Y.; Varghese, B.

    2011-01-01

    We describe a novel, minimally invasive laser technology for skin rejuvenation by creating isolated microscopic lesions within tissue below the epidermis using laser induced optical breakdown. Using an in-house built prototype device, tightly focused near-infrared laser pulses are used to create opt

  13. High-resolution imaging of ejection dynamics in laser-induced forward transfer

    NARCIS (Netherlands)

    Pohl, R.; Visser, C.W.; Römer, G.R.B.E.; Sun, C.; Huis in 't Veld, A.J.; Lohse, D.; Nakata, Yoshiki; Xianfan, Xianfan; Roth, Stephan; Neuenschwander, Beat

    2014-01-01

    Laser-induced Forward Transfer (LIFT) is a 3D direct-write method suitable for precision printing of various materials. As the ejection mechanism of picosecond LIFT has not been visualized in detail, the governing physics are not fully understood yet. Therefore, this article presents an experimental

  14. Imaging of the Ejection Process of Nanosecond Laser-induced forward Transfer of Gold

    NARCIS (Netherlands)

    Pohl, R.; Visser, C.W.; Römer, G.R.B.E.; Sun, C.; Huis in 't Veld, A.J.; Lohse, D.

    2015-01-01

    Laser-induced forward transfer is a direct-write process suitable for high precision 3D printing of several materials. However, the driving forces related to the ejection mechanism of the donor ma-terial are still under debate. To gain further insights into the ejection dynamics, this article presen

  15. Imaging of the ejection process of nanosecond laser-induced forward transfer of gold

    NARCIS (Netherlands)

    Pohl, R.; Visser, C.W.; Römer, G.R.B.E.; Sun, C.; Huis in 't Veld, A.J.; Lohse, D.

    2014-01-01

    Laser-induced forward transfer is a direct-write process suitable for high precision 3D printing of several materials. However, the driving forces related to the ejection mechanism of the donor ma-terial are still under debate. So far, most of the experimental studies of nanosecond LIFT, are based o

  16. High-resolution imaging of ejection dynamics in laser-induced forward transfer

    NARCIS (Netherlands)

    Pohl, Ralph; Visser, C.W.; Römer, Gerardus Richardus, Bernardus, Engelina; Sun, C.; Huis in 't Veld, Bert; Lohse, Detlef; Nakata, Yoshiki; Xianfan, Xianfan; Roth, Stephan; Neuenschwander, Beat

    2014-01-01

    Laser-induced Forward Transfer (LIFT) is a 3D direct-write method suitable for precision printing of various materials. As the ejection mechanism of picosecond LIFT has not been visualized in detail, the governing physics are not fully understood yet. Therefore, this article presents an experimental

  17. Laser-induced breakdown spectroscopy for quantification of heavy metals in soils and sediments

    CSIR Research Space (South Africa)

    Ambushe, AA

    2010-09-01

    Full Text Available Laser-induced breakdown spectroscopy (LIBS) will be used to determine the contents of heavy metals in soils and sediments. LIBS results will be compared with the results obtained by inductively coupled plasma-optical emission spectrometry (ICP...

  18. Minimally invasive non-thermal laser technology using laser-induced optical breakdown for skin rejuvenation

    NARCIS (Netherlands)

    Habbema, L.; Verhagen, R.; Van Hal, R.; Liu, Y.; Varghese, B.

    2011-01-01

    We describe a novel, minimally invasive laser technology for skin rejuvenation by creating isolated microscopic lesions within tissue below the epidermis using laser induced optical breakdown. Using an in-house built prototype device, tightly focused near-infrared laser pulses are used to create

  19. Two-temperature model for pulsed-laser-induced subsurface modifications in Si

    NARCIS (Netherlands)

    Verburg, P.C.; Römer, G.R.B.E.; Huis In 'T Veld, A.J.

    2014-01-01

    We investigated the laser-material interaction during the production of laser-induced subsurface modifications in silicon with a numerical model. Such modifications are of interest for subsurface wafer dicing. To predict the shape of these modifications, a two-temperature model and an optical model

  20. Capillary electrophoresis with laser-induced fluorescence detection for fast and reliable apolipoprotein E genotyping

    NARCIS (Netherlands)

    Somsen, GW; Welten, HTME; Mulder, FP; Swart, CW; Kema, IP; de Jong, GJ

    2002-01-01

    The use of capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection for the rapid determination of apolipoprotein E (apoE) genotypes was studied. High resolution and sensitive detection of the concerned DNA restriction fragments was achieved using CE buffers with hydroxypropylm

  1. Capillary Electrophoretic Immunoassay with Laser-induced Fluorescence Detection for Interferon-gamma

    Institute of Scientific and Technical Information of China (English)

    Hua ZHANG; Hai Ming WEI; Wen Rui JIN

    2004-01-01

    Capillary electrophoretic immunoassay with laser-induced fluorescence detection for recombinant human interferon-gamma (IFN-γ) was established. The limits of detection for three forms of IFN-γare 6.9 ng/L, 5.7 ng/L and 5.0 ng/L, respectively.

  2. Characterization of metal sprays created by a picosecond Laser-Induced Forward Transfer (LIFT) process

    NARCIS (Netherlands)

    Pohl, R.; Römer, G.R.B.E.; Hoppenbrouwers, M.B.; Huis in 't Veld, A.J.

    2012-01-01

    A new method to analyze and quantify results obtained with the Laser-Induced Forward Transfer (LIFT) process is presented. This experiment based characterization method was designed to investigate the spraying behavior of the LIFT process, that occurs in certain fluence regimes. This method was impl

  3. Theory Analysis of Wavelength Dependence of Laser-Induced Phase Explosion of Silicon

    Science.gov (United States)

    2008-01-01

    and P. Martin , Appl. Phys. A: Mater. Sci. Process. 79, 1695 2004. 2R. E. Russo, X. Mao, and S. S. Mao, Anal. Chem. 74, 70A 2002. 3Laser Ablation...J. Radziemski and D. A. Cremers , Laser-Induced Plasmas and Appli- cation Dekker, New York, 1989. 13J. R. Ho, C. P. Grigoropoulos, and J. A

  4. Nanoparticle detection in aqueous solutions using Raman and Laser Induced Breakdown Spectroscopy

    NARCIS (Netherlands)

    Sovago, M.; Buis, E.-J.; Sandtke, M.

    2013-01-01

    We show the chemical identification and quantification of the concentration and size of nanoparticle (NP) dispersions in aqueous solutions by using a combination of Raman Spectroscopy and Laser Induced Breakdown Spectroscopy (LIBS). The two spectroscopic techniques are applied to demonstrate the NP

  5. Nanoparticle detection in aqueous solutions using Raman and Laser Induced Breakdown Spectroscopy

    NARCIS (Netherlands)

    Sovago, M.; Buis, E.-J.; Sandtke, M.

    2013-01-01

    We show the chemical identification and quantification of the concentration and size of nanoparticle (NP) dispersions in aqueous solutions by using a combination of Raman Spectroscopy and Laser Induced Breakdown Spectroscopy (LIBS). The two spectroscopic techniques are applied to demonstrate the NP

  6. Quantification of metals in preservatively-treated lumber using laser induced breakdown spectroscopy

    Science.gov (United States)

    Brad Gething; John Janowiak; Bob Falk

    2006-01-01

    The laser induced breakdown spectroscopy (LIBS) technique was evaluated for its capability of quantifying CCA in preservative-treated wood. The results of the study reveal that the LIBS technique can be used to predict the amount of preservative based on chromium peak analysis, but further refinement of the process is necessary before the technique is practiced. The...

  7. Use of laser induced breakdown spectroscopy for the analysis of poultry products

    Science.gov (United States)

    Laser Induced Breakdown Spectroscopy is evaluated as a potential method to characterize a wide range of poultry product quality and safety characteristics. In one part of this study, breast meat quality indices, including pH and water holding capacity, were treated as dependent variables for correla...

  8. North American Symposium on Laser Induced Breakdown Spectroscopy (NASLIBS): introduction to feature issue.

    Science.gov (United States)

    Singh, Jagdish P; Almirall, Jose; Sabsabi, Mohamad; Miziolek, Andrzej W

    2012-03-01

    This feature issue highlights the topics of the 2011 North American Symposium on Laser Induced Breakdown Spectroscopy (NASLIBS). These include LIBS application to Security and Forensic, Biomedical and Environmental, Liquid Analysis and Fundamentals of LIBS, Instrumentation/Commercialization, Fusion with LIBS, and New Frontiers. © 2012 Optical Society of America

  9. Online sensor system based on laser-induced breakdown spectroscopy in quality inspection of demolition concrete

    NARCIS (Netherlands)

    Xia, H.; Bakker, M.C.M.

    2012-01-01

    In the C2CA project, an online sensor system is required to measure and control the quality and homogeneity of demolition concrete continuously. Laser-induced breakdown spectroscopy is a candidate to fulfil the objective in several tasks. Investigated is the ability of LIBS as an online

  10. Combined raman/laser-induced breakdown spectrometer: space and non-space applications

    NARCIS (Netherlands)

    Sandtke, M.; Laan, E.C.; Ahlers, B.

    2010-01-01

    TNO has developed the combination of two spectroscopic analysis methods in one instrument. Raman spectroscopy and Laser-induced Breakdown Spectroscopy (LIBS) were brought together for an instrument to be flown on the ExoMars mission from the European Space Agency (ESA) to investigate the Martian

  11. Broadband field-resolved terahertz detection via laser induced air plasma with controlled optical bias.

    Science.gov (United States)

    Li, Chia-Yeh; Seletskiy, Denis V; Yang, Zhou; Sheik-Bahae, Mansoor

    2015-05-04

    We report a robust method of coherent detection of broadband THz pulses using terahertz induced second-harmonic (TISH) generation in a laser induced air plasma together with a controlled second harmonic optical bias. We discuss a role of the bias field and its phase in the process of coherent detection. Phase-matching considerations subject to plasma dispersion are also examined.

  12. Top down fabrication of organic nanocrystals by femtosecond laser induced transfer method

    NARCIS (Netherlands)

    Fang, Hong-Hua; Yang, Jie; Ding, Ran; Feng, Jing; Chen, Qi-Dai; Sun, Hong-Bo; Fang, Honghua

    2012-01-01

    We present the preparation of nanometer-size organic crystals using femtosecond laser induced forward transfer (Fs-LIFT) method. 1,4-Bis(4-methylstyryl)benzene (BSB-Me) nanocrystals are directly deposited on the substrate to form a nanocrystal film. Size and morphology as functions of applied laser

  13. Printing Functional 3D Microdevices by Laser-Induced Forward Transfer

    NARCIS (Netherlands)

    Luo, Jun; Pohl, Ralph; Qi, Lehua; Römer, Gerardus Richardus, Bernardus, Engelina; Sun, Chao; Lohse, Detlef; Visser, C.W.

    2017-01-01

    Slender, out-of-plane metal microdevices are made in a new spatial domain, by using laser-induced forward transfer (LIFT) of metals. Here, a thermocouple with a thickness of 10 µm and a height of 250 µm, consisting of platinum and gold pillars is demonstrated. Multimaterial LIFT enables

  14. Work of adhesion in laser-induced delamination along polymer-metal interfaces

    NARCIS (Netherlands)

    Fedorov, A.; van Tijum, R.; Vellinga, W. P.; de Hosson, Jeff

    2007-01-01

    Laser-induced delamination is a recent technique aimed at characterizing adhesive strength of thin polymer coatings on metal substrates. A laser pulse is used to create a blister that initiates further delamination of the film under pressure. To process the experimental data a simple elastic model w

  15. Top down fabrication of organic nanocrystals by femtosecond laser induced transfer method

    NARCIS (Netherlands)

    Fang, Hong-Hua; Yang, Jie; Ding, Ran; Feng, Jing; Chen, Qi-Dai; Sun, Hong-Bo; Fang, Honghua

    2012-01-01

    We present the preparation of nanometer-size organic crystals using femtosecond laser induced forward transfer (Fs-LIFT) method. 1,4-Bis(4-methylstyryl)benzene (BSB-Me) nanocrystals are directly deposited on the substrate to form a nanocrystal film. Size and morphology as functions of applied laser

  16. Printing Functional 3D Microdevices by Laser-Induced Forward Transfer

    NARCIS (Netherlands)

    Luo, Jun; Pohl, Ralph; Qi, Lehua; Römer, Gerardus Richardus, Bernardus, Engelina; Sun, Chao; Lohse, Detlef; Visser, C.W.

    2017-01-01

    Slender, out-of-plane metal microdevices are made in a new spatial domain, by using laser-induced forward transfer (LIFT) of metals. Here, a thermocouple with a thickness of 10 µm and a height of 250 µm, consisting of platinum and gold pillars is demonstrated. Multimaterial LIFT enables manufacturin

  17. Characterization of metal sprays created by a picosecond Laser-Induced Forward Transfer (LIFT) process

    NARCIS (Netherlands)

    Pohl, R.; Römer, G.R.B.E.; Hoppenbrouwers, M.B.; Huis in 't Veld, A.J.

    2012-01-01

    A new method to analyze and quantify results obtained with the Laser-Induced Forward Transfer (LIFT) process is presented. This experiment based characterization method was designed to investigate the spraying behavior of the LIFT process, that occurs in certain fluence regimes. This method was impl

  18. Characterization of Metal Sprays Created by a Picosecond Laser-Induced Forward Transfer (LIFT) Process

    NARCIS (Netherlands)

    Pohl, Ralph; Römer, Gerardus Richardus, Bernardus, Engelina; Hoppenbrouwers, M.; Huis in 't Veld, Bert

    2012-01-01

    A new method to analyze and quantify results obtained with the Laser-Induced Forward Transfer (LIFT) process is presented. This experiment based characterization method was designed to investigate the spraying behavior of the LIFT process, that occurs in certain fluence regimes. This method was impl

  19. Optimization study of the femtosecond laser-induced forward-transfer process with thin aluminum films.

    Science.gov (United States)

    Bera, Sudipta; Sabbah, A J; Yarbrough, J M; Allen, C G; Winters, Beau; Durfee, Charles G; Squier, Jeff A

    2007-07-20

    The parameters for an effective laser-induced forward-transfer (LIFT) process of aluminum thin films using a femtosecond laser are studied. Deposited feature size as a function of laser fluence, donor film thickness, quality of focus, and the pulse duration are varied, providing a metric of the most desirable conditions for femtosecond LIFT with thin aluminum films.

  20. Raman and Luminescence Investigation of Rare Earth Doped Laser-Induced Crystals-in-Glass

    Science.gov (United States)

    Knorr, Brian; Stone, Adam; Jain, Himanshu; Dierolf, Volkmar

    2015-03-01

    Laser induced crystallization of glasses is a highly spatially selective process which has the potential to produce compact, integrated optics within a glass matrix. In LaBGeO5 low temperature Combined Excitation Emission Spectroscopy (CEES) revealed that erbium incorporates into both glass-ceramics and laser-induced crystals-in-glass in predominantly one type of environment (site). The energy levels of this site were quantified. The fluorescence characteristics of the erbium ions in any site in the laser-induced crystals were found to be only weakly influenced by the irradiation conditions during growth. On the other hand, a hidden parameter, potentially boron deficiency-related defects, resulted in a significant change in the incorporation behavior of the erbium ions. Scanning confocal Raman and fluorescence spectroscopy showed that the energies of the Raman modes are shifted and the erbium fluorescence intensity is inhomgeneously distributed, despite the host glass being homogeneously doped, across the cross-sections of laser-induced crystals in glass. These fluctuations within the Raman and fluorescence are spatially correlated, implying that different erbium sites form preferentially at different locations in the crystal cross-section.

  1. The spatial emergence of laser-induced periodic surface structures under lateral displacement irradiation conditions

    NARCIS (Netherlands)

    Eichstädt, Justus

    2015-01-01

    Recently, laser-induced periodic surface structures, abbreviated LIPSS, gained interest, because potential applications are seen in the field of surface functionalisation. The feasibility to produce LIPSS and the potential to influence surface functionality have been shown. But so far, the implement

  2. Analysis of irradiation processes for laser-induced periodic surface structures

    NARCIS (Netherlands)

    Eichstädt, J.; Huis in 't Veld, A.J.

    2013-01-01

    The influence of errors on the irradiation process for laser-induced periodic surface structures (LIPSS) was studied theoretically with energy density simulations. Therefore an irradiation model has been extended by a selection of technical variations. The influence of errors has been found in a dev

  3. Determination of irradiation parameters for laser-induced periodic surface structures

    NARCIS (Netherlands)

    Eichstädt, J.; Römer, G.R.B.E.; Huis in 't Veld, A.J.

    2013-01-01

    The spatial emergence of laser-induced periodic surface structures (LIPSS) on single-crystalline silicon, upon irradiation with linearly polarized picosecond laser pulses (wavelength λ = 1030 nm, pulse duration τ = 6.7 ps, pulse repetition frequency fp = 1 kHz) was studied theoretically and experime

  4. Model of Laser-Induced Temperature Changes in Solid-State Optical Refrigerators

    Science.gov (United States)

    2010-01-01

    and amplifiers. Light-induced heating also plays a key role in laser ablation,10 photothermal therapy ,11–13 laser-induced damage of tissue, and... reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of

  5. Calculation and optimization of sample identification by laser induced breakdown spectroscopy via correlation analysis

    NARCIS (Netherlands)

    Lentjes, M.; Dickmann, K.; Meijer, J.

    2007-01-01

    Linear correlation analysis may be used as a technique for the identification of samples with a very similar chemical composition by laser induced breakdown spectroscopy. The spectrum of the “unknown” sample is correlated with a library of reference spectra. The probability of identification by

  6. Plume expansion of a laser-induced plasma studied with the particle-in-cell method

    DEFF Research Database (Denmark)

    Ellegaard, Ole; Nedela, T; Urbassek, H;

    2002-01-01

     The initial stage of laser-induced plasma plume expansion from a solid in vacuum and the effect of the Coulomb field have been studied. We have performed a one-dimensional numerical calculation by mapping the charge on a computational grid according to the particle-in-cell (PIC) method of Birdsall...

  7. Plume expansion of a laser-induced plasma studied with the particle-in-cell method

    DEFF Research Database (Denmark)

    Ellegaard, O.; Nedelea, T.; Schou, Jørgen;

    2002-01-01

    The initial stage of laser-induced plasma plume expansion from a solid in vacuum and the effect of the Coulomb field have been studied. We have performed a one-dimensional numerical calculation by mapping the charge on a computational grid according to the particle-in-cell (PIC) method of Birdsall...

  8. Velocity Diagnosis of Critical Surface at Microwave Band in Laser-Induced Plasma

    Institute of Scientific and Technical Information of China (English)

    WU Ying; WANG Junyan; BAI Shunbo; CHEN Jianping; CHU Ran; YUN Xiaohua; NI Xiaowu

    2008-01-01

    The velocity of critical surface at microwave band in laser-induced plasma was mea-sured and the results are presented. The results indicate that the velocity of critical surface with low electron density is larger than that with the high one; and the velocity of critical surface increases with the laser power density.

  9. Recognition of edible oil by using BP neural network and laser induced fluorescence spectrum

    Science.gov (United States)

    Mu, Tao-tao; Chen, Si-ying; Zhang, Yin-chao; Guo, Pan; Chen, He; Zhang, Hong-yan; Liu, Xiao-hua; Wang, Yuan; Bu, Zhi-chao

    2013-09-01

    In order to accomplish recognition of the different edible oil we set up a laser induced fluorescence spectrum system in the laboratory based on Laser induced fluorescence spectrum technology, and then collect the fluorescence spectrum of different edible oil by using that system. Based on this, we set up a fluorescence spectrum database of different cooking oil. It is clear that there are three main peak position of different edible oil from fluorescence spectrum chart. Although the peak positions of all cooking oil were almost the same, the relative intensity of different edible oils was totally different. So it could easily accomplish that oil recognition could take advantage of the difference of relative intensity. Feature invariants were extracted from the spectrum data, which were chosen from the fluorescence spectrum database randomly, before distinguishing different cooking oil. Then back propagation (BP) neural network was established and trained by the chosen data from the spectrum database. On that basis real experiment data was identified by BP neural network. It was found that the overall recognition rate could reach as high as 83.2%. Experiments showed that the laser induced fluorescence spectrum of different cooking oil was very different from each other, which could be used to accomplish the oil recognition. Laser induced fluorescence spectrum technology, combined BP neural network,was fast, high sensitivity, non-contact, and high recognition rate. It could become a new technique to accomplish the edible oil recognition and quality detection.

  10. Quantitative laser-induced fluorescence measurements of nitric oxide in a heavy-duty Diesel engine

    NARCIS (Netherlands)

    Verbiezen, K.; Klein-Douwel, R. J. H.; van Viet, A. P.; Donkerbroek, A. J.; Meerts, W. L.; Dam, N. J.; ter Meulen, J. J.

    2007-01-01

    We present quantitative, in-cylinder, UV-laser-induced fluorescence measurements of nitric oxide in a heavy-duty Diesel engine. Processing of the raw fluorescence signals includes a detailed correction, based on additional measurements, for the effect of laser beam and fluorescence attenuation, and

  11. Verification of a characterization method of the laser-induced selective activation based on industrial lasers

    DEFF Research Database (Denmark)

    Zhang, Yang; Hansen, Hans Nørgaard; Tang, Peter T.

    2013-01-01

    In this article, laser-induced selective activation (LISA) for subsequent autocatalytic copper plating is performed by several types of industrial scale lasers, including a Nd:YAG laser, a UV laser, a fiber laser, a green laser, and a short pulsed laser. Based on analysis of all the laser-machine...

  12. Ejection Regimes in Picosecond Laser-Induced Forward Transfer of Metals

    NARCIS (Netherlands)

    Pohl, Ralph; Visser, Claas Willem; Römer, Gert-Willem; Lohse, Detlef; Sun, Chao; Huis in 't Veld, Bert

    2015-01-01

    Laser-induced forward transfer (LIFT) is a 3D direct-write method suitable for precision printing of various materials, including pure metals. To understand the ejection mechanism and thereby improve deposition, here we present visualizations of ejection events at high-spatial (submicrometer) and hi

  13. Toward 3D Printing of Pure Metals by Laser-Induced Forward Transfer

    NARCIS (Netherlands)

    Visser, Claas Willem; Pohl, Ralph; Sun, Chao; Römer, Gert-Willem; Huis in 't Veld, Bert; Lohse, Detlef

    2015-01-01

    3D printing of common metals is highly challenging because metals are generally solid at room conditions. Copper and gold pillars are manufactured with a resolution below 5 μm and a height up to 2 mm, using laser-induced forward transfer to create and eject liquid metal droplets. The solidified drop

  14. Printing Functional 3D Microdevices by Laser-Induced Forward Transfer

    NARCIS (Netherlands)

    Luo, Jun; Pohl, Ralph; Qi, Lehua; Römer, Gert-Willem; Sun, Chao; Lohse, Detlef; Visser, Claas Willem

    2017-01-01

    Slender, out-of-plane metal microdevices are made in a new spatial domain, by using laser-induced forward transfer (LIFT) of metals. Here, a thermocouple with a thickness of 10 µm and a height of 250 µm, consisting of platinum and gold pillars is demonstrated. Multimaterial LIFT enables manufacturin

  15. Toward 3D Printing of Pure Metals by Laser-Induced Forward Transfer

    NARCIS (Netherlands)

    Visser, C.W.; Pohl, Ralph; Sun, Chao; Römer, Gerardus Richardus, Bernardus, Engelina; Huis in 't Veld, Bert; Lohse, Detlef

    2015-01-01

    3D printing of common metals is highly challenging because metals are generally solid at room conditions. Copper and gold pillars are manufactured with a resolution below 5 μm and a height up to 2 mm, using laser-induced forward transfer to create and eject liquid metal droplets. The solidified

  16. Application of Ansys Program in Laser-induced Interstitial Thermotherapy (LITT)

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The influence of heat source by laser irradiating on tissue temperature was simulated with the Ansys program, and the distribution of tissue temperature under the heat source was shown. Compared with others, the simulation method with ansys program is more intuitionistic and can offer very good reference for Laser- induced interstitial thernotherapy.

  17. Femtosecond laser induced breakdown spectroscopy of silver within surrogate high temperature gas reactor fuel coated particles

    CSIR Research Space (South Africa)

    Roberts, DE

    2010-11-01

    Full Text Available been studied with femtosecond Laser Induced Breakdown Spectroscopy (femto-LIBS). The SiC layer of the TRISO coated particle is the main barrier to metallic and gaseous fission products of which 110mAg is of particular interest for direct cycle high...

  18. Quantum Hooke's law to classify pulse laser induced ultrafast melting.

    Science.gov (United States)

    Hu, Hao; Ding, Hepeng; Liu, Feng

    2015-02-03

    Ultrafast crystal-to-liquid phase transition induced by femtosecond pulse laser excitation is an interesting material's behavior manifesting the complexity of light-matter interaction. There exist two types of such phase transitions: one occurs at a time scale shorter than a picosecond via a nonthermal process mediated by electron-hole plasma formation; the other at a longer time scale via a thermal melting process mediated by electron-phonon interaction. However, it remains unclear what material would undergo which process and why? Here, by exploiting the property of quantum electronic stress (QES) governed by quantum Hooke's law, we classify the transitions by two distinct classes of materials: the faster nonthermal process can only occur in materials like ice having an anomalous phase diagram characterized with dTm/dP melting temperature and P is pressure, above a high threshold laser fluence; while the slower thermal process may occur in all materials. Especially, the nonthermal transition is shown to be induced by the QES, acting like a negative internal pressure, which drives the crystal into a "super pressing" state to spontaneously transform into a higher-density liquid phase. Our findings significantly advance fundamental understanding of ultrafast crystal-to-liquid phase transitions, enabling quantitative a priori predictions.

  19. Selective-fluid-filled photonic crystal fibers and applications

    Science.gov (United States)

    Wang, Yiping; Liao, Changrui; Zhong, Xiaoyong; Li, Zhengyong; Liu, Yingjie; Zhou, Jiangtao; Yang, Kaiming

    2013-08-01

    A selective-filling technique was demonstrated to improve the optical properties of photonic crystal fibres (PCFs). Such a technique can be used to fill one or more fluid samples selectively into desired air holes. The technique is based on drilling a hole or carving a groove on the surface of a PCF to expose selected air holes to atmosphere by the use of a micromachining system comprising of a femtosecond infrared laser and a microscope. The exposed section was immersed into a fluid and the air holes are then filled through the well-known capillarity action. Provided two or more grooves are fabricated on different locations and different orientation along the fibre surface, different fluids may be filled into different airholes to form a hybrid fibre. As an example, we filled half of a pure-silica PCF by a fluid with n=1.480 by carving a rectangular groove on the fibre. Consequently, the half-filled PCF became a bandgap-guiding structure (upper half), resulted from a higher refractive index in the fluid rods than in the fibre core, and three bandgaps were observed within the wavelength range from 600 to 1700 nm. Whereas, the lower half (unfilled holes) of the fibre remains an air/silica index-guiding structure. When the hybrid PCF is bent, its bandgaps gradually narrowed, resulted from the shifts of the bandgap edges. The bandgap edges had distinct bend-sensitivities when the hybrid PCF was bent toward different directions. Especially, the bandgaps are hardly affected when the half-filled PCF was bent toward the fluid-filled region. Such unique bend properties could be used to monitor simultaneously the bend directions and the curvature of the engineering structures.

  20. Black holes

    CERN Document Server

    Chrúsciel, P T

    2002-01-01

    This paper is concerned with several not-quantum aspects of black holes, with emphasis on theoretical and mathematical issues related to numerical modeling of black hole space-times. Part of the material has a review character, but some new results or proposals are also presented. We review the experimental evidence for existence of black holes. We propose a definition of black hole region for any theory governed by a symmetric hyperbolic system of equations. Our definition reproduces the usual one for gravity, and leads to the one associated with the Unruh metric in the case of Euler equations. We review the global conditions which have been used in the Scri-based definition of a black hole and point out the deficiencies of the Scri approach. Various results on the structure of horizons and apparent horizons are presented, and a new proof of semi-convexity of horizons based on a variational principle is given. Recent results on the classification of stationary singularity-free vacuum solutions are reviewed. ...

  1. Emission Characteristics of Laser-Induced Plasma Using Collinear Long and Short Dual-Pulse Laser-Induced Breakdown Spectroscopy (LIBS).

    Science.gov (United States)

    Wang, Zhenzhen; Deguchi, Yoshihiro; Liu, Renwei; Ikutomo, Akihiro; Zhang, Zhenzhen; Chong, Daotong; Yan, Junjie; Liu, Jiping; Shiou, Fang-Jung

    2017-09-01

    Collinear long and short dual-pulse laser-induced breakdown spectroscopy (DP-LIBS) was employed to clarify the emission characteristics from laser-induced plasma. The plasma was sustained and became stable by the long pulse-width laser with the pulse width of 60 μs under free running (FR) conditions as an external energy source. Comparing the measurement results of stainless steel in air using single-pulse LIBS (SP-LIBS) and DP-LIBS, the emission intensity was markedly enhanced using DP-LIBS. The temperature of plasma induced by DP-LIBS was maintained at a higher temperature under different gate delay time and short pulse-width laser power conditions compared with those measured using short SP-LIBS. Moreover, the variation rates of plasma temperatures measured using DP-LIBS were also lower. The superior detection ability was verified by the measurement of aluminum sample in water. The spectra were clearly detected using DP-LIBS, whereas it cannot be identified using SP-LIBS of short and long pulse widths. The effects of gate delay time and short pulse-width laser power were also discussed. These results demonstrate the feasibility and enhanced detection ability of the proposed collinear long and short DP-LIBS method.

  2. Inkjet Printing of Viscous Monodisperse Microdroplets by Laser-Induced Flow Focusing

    Science.gov (United States)

    Delrot, Paul; Modestino, Miguel A.; Gallaire, François; Psaltis, Demetri; Moser, Christophe

    2016-08-01

    The on-demand generation of viscous microdroplets to print functional or biological materials remains challenging using conventional inkjet-printing methods, mainly due to aggregation and clogging issues. In an effort to overcome these limitations, we implement a jetting method to print viscous microdroplets by laser-induced shockwaves. We experimentally investigate the dependence of the jetting regimes and the droplet size on the laser-pulse energy and on the inks' physical properties. The range of printable liquids with our device is significantly extended compared to conventional inkjet printers's performances. In addition, the laser-induced flow-focusing phenomenon allows us to controllably generate viscous microdroplets up to 210 mPa s with a diameter smaller than the nozzle from which they originated (200 μ m ). Inks containing proteins are printed without altering their functional properties, thus demonstrating that this jetting technique is potentially suitable for bioprinting.

  3. Mesons from Laser-Induced Processes in Ultra-Dense Hydrogen H(0).

    Science.gov (United States)

    Holmlid, Leif

    2017-01-01

    Large signals of charged light mesons are observed in the laser-induced particle flux from ultra-dense hydrogen H(0) layers. The mesons are formed in such layers on metal surfaces using muons in the particle beam agree with the results. Muons are detected separately by standard scintillation detectors in laser-induced processes in ultra-dense hydrogen H(0) as published previously. The muons formed do not decay appreciably within the flight distances used here. Most of the laser-ejected particle flux with MeV energy is not deflected by the magnetic fields and is thus neutral, either being neutral kaons or the ultra-dense HN(0) precursor clusters. Photons give only a minor part of the detected signals. PACS: 67.63.Gh, 14.40.-n, 79.20.Ds, 52.57.-z.

  4. An intelligent artificial throat with sound-sensing ability based on laser induced graphene

    Science.gov (United States)

    Tao, Lu-Qi; Tian, He; Liu, Ying; Ju, Zhen-Yi; Pang, Yu; Chen, Yuan-Quan; Wang, Dan-Yang; Tian, Xiang-Guang; Yan, Jun-Chao; Deng, Ning-Qin; Yang, Yi; Ren, Tian-Ling

    2017-02-01

    Traditional sound sources and sound detectors are usually independent and discrete in the human hearing range. To minimize the device size and integrate it with wearable electronics, there is an urgent requirement of realizing the functional integration of generating and detecting sound in a single device. Here we show an intelligent laser-induced graphene artificial throat, which can not only generate sound but also detect sound in a single device. More importantly, the intelligent artificial throat will significantly assist for the disabled, because the simple throat vibrations such as hum, cough and scream with different intensity or frequency from a mute person can be detected and converted into controllable sounds. Furthermore, the laser-induced graphene artificial throat has the advantage of one-step fabrication, high efficiency, excellent flexibility and low cost, and it will open practical applications in voice control, wearable electronics and many other areas.

  5. Effect of cylindrical cavity height on laser-induced breakdown spectroscopy with spatial confinement

    Science.gov (United States)

    Junfeng, Shao; Tingfeng, Wang; Jin, Guo; Anmin, Chen; Mingxing, Jin

    2017-02-01

    In this paper, we present a study on the spatial confinement effect of laser-induced plasma with a cylindrical cavity in laser-induced breakdown spectroscopy (LIBS). The emission intensity with the spatial confinement is dependent on the height of the confinement cavity. It is found that, by selecting the appropriate height of cylindrical cavity, the signal enhancement can be significantly increased. At the cylindrical cavity (diameter = 2 mm) with a height of 6 mm, the enhancement ratio has the maximum value (approximately 8.3), and the value of the relative standard deviation (RSD) (7.6%) is at a minimum, the repeatability of LIBS signal is best. The results indicate that the height of confinement cavity is very important for LIBS technique to reduce the limit of detection and improve the precision.

  6. Fluorocoxib A enables targeted detection of cyclooxygenase-2 in laser-induced choroidal neovascularization

    Science.gov (United States)

    Uddin, Md. Jashim; Moore, Chauca E.; Crews, Brenda C.; Daniel, Cristina K.; Ghebreselasie, Kebreab; McIntyre, J. Oliver; Marnett, Lawrence J.; Jayagopal, Ashwath

    2016-09-01

    Ocular angiogenesis is a blinding complication of age-related macular degeneration and other retinal vascular diseases. Clinical imaging approaches to detect inflammation prior to the onset of neovascularization in these diseases may enable early detection and timely therapeutic intervention. We demonstrate the feasibility of a previously developed cyclooxygenase-2 (COX-2) targeted molecular imaging probe, fluorocoxib A, for imaging retinal inflammation in a mouse model of laser-induced choroidal neovascularization. This imaging probe exhibited focal accumulation within laser-induced neovascular lesions, with minimal detection in proximal healthy tissue. The selectivity of the probe for COX-2 was validated in vitro and by in vivo retinal imaging with nontargeted 5-carboxy-X-rhodamine dye, and by blockade of the COX-2 active site with nonfluorescent celecoxib prior to injection of fluorocoxib A. Fluorocoxib A can be utilized for imaging COX-2 expression in vivo for further validation as an imaging biomarker in retinal diseases.

  7. The application of time decay characteristics of laser-induced fluorescence in the classification of vegetation.

    Science.gov (United States)

    Gong, Wei; Yang, Jian; Shi, Shuo; Du, Lin; Sun, Jia; Song, Shalei

    2017-02-01

    In this study, the time decay of the chlorophyll fluorescence intensity (TDCFI) of vegetation was measured based on laser-induced fluorescence (LIF) technology with a 355 nm laser serving as the excitation light source. The pseudo-color diagram of the TDCFI (PDTDCFIs) was proposed for use as a characteristic fingerprint for the analysis of various plant species based on variations in the fluorescence intensity over time. Compared with the steady-state fluorescence spectra, two-dimensional PDTDCFIs contained more spectral information, including variations in both the shape of the laser-induced fluorescence spectra and the relative intensity. The experimental results demonstrated that the PDTDCFIs of various plant species show distinct differences, and this was successfully applied in the classification of plant species. Therefore, the PDTDCFIs of plants could provide researchers with a more reliable and useful tool for the characterization of vegetation. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  8. An intelligent artificial throat with sound-sensing ability based on laser induced graphene

    Science.gov (United States)

    Tao, Lu-Qi; Tian, He; Liu, Ying; Ju, Zhen-Yi; Pang, Yu; Chen, Yuan-Quan; Wang, Dan-Yang; Tian, Xiang-Guang; Yan, Jun-Chao; Deng, Ning-Qin; Yang, Yi; Ren, Tian-Ling

    2017-01-01

    Traditional sound sources and sound detectors are usually independent and discrete in the human hearing range. To minimize the device size and integrate it with wearable electronics, there is an urgent requirement of realizing the functional integration of generating and detecting sound in a single device. Here we show an intelligent laser-induced graphene artificial throat, which can not only generate sound but also detect sound in a single device. More importantly, the intelligent artificial throat will significantly assist for the disabled, because the simple throat vibrations such as hum, cough and scream with different intensity or frequency from a mute person can be detected and converted into controllable sounds. Furthermore, the laser-induced graphene artificial throat has the advantage of one-step fabrication, high efficiency, excellent flexibility and low cost, and it will open practical applications in voice control, wearable electronics and many other areas. PMID:28232739

  9. Planar laser-induced fluorescence fuel imaging during gas-turbine relight

    DEFF Research Database (Denmark)

    Read, Robert; Rogerson, J.W.; Hochgreb, S.

    2013-01-01

    This experimental study investigates the influence of fuel distribution on ignition outcome during high-altitude relight of a gas turbine. Planar laser-induced fluorescence is used to image fuel inside a lean direct-injection combustor under realistic conditions. A novel apparatus is developed...... to permit planar laser-induced fluorescence imaging, in which large quantities of poorly atomized fuel impinges on the internal surfaces of the combustor. Results reveal high variability in atomization quality. In the absence of flame, small droplets are confined to areas of recirculating flow, whereas...... of ignition when the airflow rate is high. In the presence of flame, medium-sized burning droplets are observed close to the injector centerline. Flame interference resulting from fluorescence of polycyclic aromatic hydrocarbons is apparent, but small, suggesting that kerosene planar laser...

  10. Effect of laser-induced photodissociation of oxyhemoglobin on biomedical processes

    Science.gov (United States)

    Asimov, Mustafo M.; Asimov, Rustam M.; Mirshahi, M.; Gisbrecht, Alexander

    2001-04-01

    In the present report we draw attention to the phenomenon of laser-induced photodissociation of oxyhemoglobin in cutaneous blood vessels as an important factor in biostimulating and therapeutic action of low energy laser radiation. Calculations of absorption efficiency of laser radiation both by oxyhemoglobin and carbon monoxide hemoglobin were carried out by a computer simulation using Kubelka-Munk model of tissue. It has been shown that the absorption of the oxyhemoglobin in the visible region corresponding to the Q-band of absorption spectra possesses a relatively high selectivity. The obtained results are discussed in terms of developing new methods for wound healing, as well as for carbon monoacid poisoning. Some aspects of the laser-induced photodissociation of oxyhemoglobin complexes are discussed in view of its practical use for developing new diagnostic methods. An attractive way to use this phenomenon is monitoring of local concentrations of oxygen by laser light irradiation.

  11. Identification of inks and structural characterization of contemporary artistic prints by laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Oujja, M. [Instituto de Quimica Fisica Rocasolano, CSIC, Serrano 119, 28006 Madrid (Spain); Vila, A. [Departament de Pintura, Conservacio-Restauracio, Facultat de Belles Arts, Universitat de Barcelona, Pau Gargallo 4, 08028 Barcelona (Spain); Rebollar, E. [Instituto de Quimica Fisica Rocasolano, CSIC, Serrano 119, 28006 Madrid (Spain); Garcia, J.F. [Departament de Pintura, Conservacio-Restauracio, Facultat de Belles Arts, Universitat de Barcelona, Pau Gargallo 4, 08028 Barcelona (Spain); Castillejo, M. [Instituto de Quimica Fisica Rocasolano, CSIC, Serrano 119, 28006 Madrid (Spain)]. E-mail: marta.castillejo@iqfr.csic.es

    2005-08-31

    Identification of the inks used in artistic prints and the order in which different ink layers have been applied on a paper substrate are important factors to complement the classical stylistic aspects for the authentication of this type of objects. Laser-induced breakdown spectroscopy (LIBS) is investigated to determine the chemical composition and structural distribution of the constituent materials of model prints made by applying one or two layers of several blue and black inks on an Arches paper substrate. By using suitable laser excitation conditions, identification of the inks was possible by virtue of emissions from key elements present in their composition. Analysis of successive spectra on the same spot allowed the identification of the order in which the inks were applied on the paper. The results show the potential of laser-induced breakdown spectroscopy for the chemical and structural characterization of artistic prints.

  12. Picosecond laser-induced breakdown at 5321 and 5347 A - Observation of frequency-dependent behavior

    Science.gov (United States)

    Smith, W. L.; Bechtel, J. H.; Bloembergen, N.

    1977-01-01

    A study is presented of picosecond laser-induced breakdown at 3547 and 5321 A of several materials. The thresholds obtained for breakdown at 5321 A are compared to previous results obtained at 1.064 microns using the same laser system. This comparison illustrates the transition of bulk laser-induced breakdown as it becomes increasingly frequency dependent. UV picosecond pulses are obtained by mixing 5321 A and 1.064 micron pulses in a KH2PO4 crystal. Upper and lower bounds on the 3547 A breakdown threshold are defined, although some effects of walk-off distortion and self-focusing are observed. The results are discussed with reference to models for the intrinsic processes involved in the breakdown, i.e., avalanche and multiphoton ionization.

  13. Investigation of laser induced breakdown in liquid nitromethane using nanosecond shadowgraphy

    Science.gov (United States)

    Guo, Wencan; Zheng, Xianxu; Yu, Guoyang; Zhao, Jun; Zeng, Yangyang; Liu, Cangli

    2016-09-01

    A nanosecond time-resolved shadowgraphy is performed to observe a laser-induced breakdown in nitromethane. The digital delays are introduced between a pump beam and an illumination light to achieve a measuring range from 40 ns to 100 ms, which enable us to study the shock wave propagation, bubble dynamics, and other process of the laser-induced breakdown. Compared with distilled water, there are two obvious differences observed in nitromethane: (1) the production of a non-evaporative gas at the final stage, and (2) an absence of the secondary shock wave after the first collapse of the bubble. We also calculated the bubble energy in nitromethane and distilled water under a different incident energy. The results indicate that the bubble energy in nitromethane is more than twice as large as that in water. It is suggested that chemical reactions contribute to the releasing of energy.

  14. Mechanisms of two-color laser-induced field-free molecular orientation.

    Science.gov (United States)

    Spanner, Michael; Patchkovskii, Serguei; Frumker, Eugene; Corkum, Paul

    2012-09-14

    Two mechanisms of two-color (ω+2ω) laser-induced field-free molecular orientation, based on the hyperpolarizability and ionization depletion, are explored and compared. The CO molecule is used as a computational example. While the hyperpolarizability mechanism generates small amounts of orientation at intensities below the ionization threshold, ionization depletion quickly becomes the dominant mechanism as soon as ionizing intensities are reached. Only the ionization mechanism leads to substantial orientation (e.g., on the order of ≳0.1). For intensities typical of laser-induced molecular alignment and orientation experiments, the two mechanisms lead to robust, characteristic timings of the field-free orientation wave-packet revivals relative to the alignment revivals and the revival time. The revival timings can be used to detect the active orientation mechanism experimentally.

  15. Measurements of egg shell plasma parameters using laser-induced breakdown spectroscopy

    Indian Academy of Sciences (India)

    Wenfeng Luo; Xiaoxia Zhao; Shuyuan Lv; Haiyan Zhu

    2015-07-01

    Measurements of 1064 nm laser-induced egg shell plasma parameters are presented in this paper. Of special interests were its elemental identification and the determination of spectroscopic temperature and electron density. The electron temperature of 5956 K was inferred using an improved iterative Boltzmann plot method with six calcium atomic emission lines, and the electron number density of 6.1 × 1016 cm−3 was determined by measuring the width of Stark-broadened once-ionized calcium line at 393.37 nm. Based on the experimental results, the laser-induced egg shell plasma was verified to be optically thin and satisfy local thermodynamic equilibrium (LTE). Furthermore, experiments also demonstrated that the loss of energy due to the reflection of the laser beam from the plasma can be neglected and the inverse bremsstrahlung (IB) absorption was the dominant mechanism of plasma heating at the IR wavelength.

  16. Quantitative Classification of Quartz by Laser Induced Breakdown Spectroscopy in Conjunction with Discriminant Function Analysis

    Directory of Open Access Journals (Sweden)

    A. Ali

    2016-01-01

    Full Text Available A responsive laser induced breakdown spectroscopic system was developed and improved for utilizing it as a sensor for the classification of quartz samples on the basis of trace elements present in the acquired samples. Laser induced breakdown spectroscopy (LIBS in conjunction with discriminant function analysis (DFA was applied for the classification of five different types of quartz samples. The quartz plasmas were produced at ambient pressure using Nd:YAG laser at fundamental harmonic mode (1064 nm. We optimized the detection system by finding the suitable delay time of the laser excitation. This is the first study, where the developed technique (LIBS+DFA was successfully employed to probe and confirm the elemental composition of quartz samples.

  17. Electron backscatter diffraction characterization of laser-induced periodic surface structures on nickel surface

    Energy Technology Data Exchange (ETDEWEB)

    Sedao, Xxx, E-mail: sedao.xxx@gmail.com [Laboratoire Hubert Curien, Université Jean Monnet, 42000 St-Etienne (France); Maurice, Claire [Laboratoire Georges Friedel, Ecole Nationale Supérieure des Mines, 42023 St-Etienne (France); Garrelie, Florence; Colombier, Jean-Philippe; Reynaud, Stéphanie [Laboratoire Hubert Curien, Université Jean Monnet, 42000 St-Etienne (France); Quey, Romain; Blanc, Gilles [Laboratoire Georges Friedel, Ecole Nationale Supérieure des Mines, 42023 St-Etienne (France); Pigeon, Florent [Laboratoire Hubert Curien, Université Jean Monnet, 42000 St-Etienne (France)

    2014-05-01

    Graphical abstract: -- Highlight: •Lattice rotation and its distribution in laser-induced periodic surface structures (LIPSS) and the subsurface region on a nickel substrate are revealed using electron backscatter diffraction (EBSD). -- Abstract: We report on the structural investigation of laser-induced periodic surface structures (LIPSS) generated in polycrystalline nickel target after multi-shot irradiation by femtosecond laser pulses. Electron backscatter diffraction (EBSD) is used to reveal lattice rotation caused by dislocation storage during LIPSS formation. Localized crystallographic damages in the LIPSS are detected from both surface and cross-sectional EBSD studies. A surface region (up to 200 nm) with 1–3° grain disorientation is observed in localized areas from the cross-section of the LIPSS. The distribution of the local disorientation is inhomogeneous across the LIPSS and the subsurface region.

  18. Nanosecond laser-induced periodic surface structuring of cross-linked azo-polymer films

    Energy Technology Data Exchange (ETDEWEB)

    Berta, Marco, E-mail: marco.berta@univ-amu.fr [Aix Marseille Université, CNRS, ICR (Institut de Chimie Radicalaire) UMR 7273, 13397 Marseille Cedex 20 (France); Biver, Émeric [Aix Marseille Université, CNRS, LP3 UMR 7341, 13288 Marseille (France); Maria, Sébastien; Phan, Trang N.T. [Aix Marseille Université, CNRS, ICR (Institut de Chimie Radicalaire) UMR 7273, 13397 Marseille Cedex 20 (France); D’Aleo, Anthony; Delaporte, Philippe; Fages, Frederic [Aix Marseille Université, CNRS, CINaM UMR 7325, 13288 Marseille (France); Gigmes, Didier [Aix Marseille Université, CNRS, ICR (Institut de Chimie Radicalaire) UMR 7273, 13397 Marseille Cedex 20 (France)

    2013-10-01

    In this work we discuss the response to laser ablation of a poly(4-vinylbenzyl azide-random-methyl methacrylate) (p((S-N{sub 3})-r-MMA)) random copolymer. This material is cross-linkable thermally and upon exposure to UV light, and on cross-linked films the irradiation with a 248 nm ns KrF laser induces the formation of laser induced periodical surface structure (LIPSS). The LIPSS morphology is dependent on the amount of 4-vinylbenzyl azide (S-N{sub 3}) groups in the pristine copolymer. We propose a crosslinking mechanism based on the scission of azide with formation of azo groups and we discuss the possible relationship between this chemical modifications and the formation of ripples on the bottom of laser ablation cavities.

  19. Nanosecond laser-induced periodic surface structuring of cross-linked azo-polymer films

    Science.gov (United States)

    Berta, Marco; Biver, Émeric; Maria, Sébastien; Phan, Trang N. T.; D'Aleo, Anthony; Delaporte, Philippe; Fages, Frederic; Gigmes, Didier

    2013-10-01

    In this work we discuss the response to laser ablation of a poly(4-vinylbenzyl azide-random-methyl methacrylate) (p((S-N3)-r-MMA)) random copolymer. This material is cross-linkable thermally and upon exposure to UV light, and on cross-linked films the irradiation with a 248 nm ns KrF laser induces the formation of laser induced periodical surface structure (LIPSS). The LIPSS morphology is dependent on the amount of 4-vinylbenzyl azide (S-N3) groups in the pristine copolymer. We propose a crosslinking mechanism based on the scission of azide with formation of azo groups and we discuss the possible relationship between this chemical modifications and the formation of ripples on the bottom of laser ablation cavities.

  20. Note: A novel technique for analysis of aqueous solutions by laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Rusak, D A; Anthony, T P; Bell, Z T

    2015-11-01

    Surface-enhanced Raman spectroscopy (SERS) substrates typically consist of gold or silver nanoparticles deposited on a non-conductive substrate. In Raman spectroscopy, the nanoparticles produce an enhancement of the electromagnetic field which, in turn, leads to greater electronic excitation of molecules in the local environment. Here, we show that these same surfaces can be used to enhance the signal-to-noise ratio obtained in laser-induced breakdown spectroscopy of aqueous solutions. In this case, the SERS substrates not only lower breakdown thresholds and lead to more efficient plasma initiation but also provide an appropriately wettable surface for the deposition of the liquid. We refer to this technique as surface-enhanced laser-induced breakdown spectroscopy.

  1. Serum Protein Profile Study of Clinical Samples Using High Performance Liquid Chromatography-Laser Induced Fluorescence

    DEFF Research Database (Denmark)

    Karemore, Gopal Raghunath; Ukendt, Sujatha; Rai, Lavanya

    2009-01-01

    The serum protein profiles of normal subjects, patients diagnosed with cervical cancer, and oral cancer were recorded using High Performance Liquid Chromatography combined with Laser Induced Fluorescence detection (HPLC-LIF). Serum protein profiles of the above three classes were tested for estab......The serum protein profiles of normal subjects, patients diagnosed with cervical cancer, and oral cancer were recorded using High Performance Liquid Chromatography combined with Laser Induced Fluorescence detection (HPLC-LIF). Serum protein profiles of the above three classes were tested...... for establishing the ability of HPLC-LIF protein profiling technique for discrimination, using hard clustering and Fuzzy clustering methods. The clustering algorithms have quite successfully classified the profiles as belonging to normal, cancer of cervix, and oral cancer conditions....

  2. Simultaneous laser induced breakdown spectroscopy and Pd-assisted methane decomposition at different pressures

    Energy Technology Data Exchange (ETDEWEB)

    Reyhani, A. [Phys. Dept., Faculty of Science, Imam Khomeini International University, Qazvin, 34149-16818 (Iran, Islamic Republic of); Mortazavi, S.Z. [Phys. Dept., Amirkabir University of Technology, P.O. Box 15875-4413, Tehran (Iran, Islamic Republic of); Parvin, P., E-mail: parvin@aut.ac.ir [Phys. Dept., Amirkabir University of Technology, P.O. Box 15875-4413, Tehran (Iran, Islamic Republic of); Mahmoudi, Z. [Phys. Dept., Amirkabir University of Technology, P.O. Box 15875-4413, Tehran (Iran, Islamic Republic of)

    2012-08-15

    Methane decomposition is investigated during Pd-assisted laser induced plasma in the controlled chamber at various pressures using Q-switched Nd:YAG laser. Real time LIBS monitoring is applied to reveal the involved mechanisms during methane decomposition by inspecting the plasma parameters at mano-metric pressures of 1 to 10 mbar. The dependence of electron density and plasma temperature with pressure is also studied. It is shown that the plasma recreates higher hydrocarbons during the decomposition of methane. In addition, Fourier transform infrared spectroscopy, gas chromatography, scanning electron microscopy and transmission electron microscopy are applied to support the findings. - Highlights: Black-Right-Pointing-Pointer Simultaneous laser induced breakdown spectroscopy Black-Right-Pointing-Pointer Pd-assisted methane decomposition Black-Right-Pointing-Pointer Nanosecond pulsed laser decomposition of methane Black-Right-Pointing-Pointer Generation of higher hydrocarbon Black-Right-Pointing-Pointer Dependence of electron density and temperature of induced plasma with pressure.

  3. Hyperspectral laser-induced flourescence imaging for assessing internal quality of kiwi fruit

    Science.gov (United States)

    Liu, Muhua; Liao, Yifeng; Zhou, Xiaomei

    2008-03-01

    This paper describes an experimental study on non-destructive methods for predicting quality of kiwifruits using fluorescence imaging. The method is based on hyperspectral laser-induced fluorescence imaging in the region between 700 and 1110 nm, and estimates the kiwifruits quality in terms of internal sugar content and firmness. A station for acquiring hyperspectral laser-induced fluorescence imaging has been designed and carefully choosing each component. The fluorescence imaging acquired by the station has been pre-processed by selecting regions of interest (ROIs) of 50 100 × pixels. A line regressing prediction method estimates the quality of kiwifruit samples. The results obtained in classification show that the station and prediction model enables the correct discrimination of kiwifruits internal sugar content and firmness with a percentage of r= 98.5%, SEP=0.4 and r=99.9%, SEP=0.62.

  4. Investigation of Laser-Induced Damage on Multi-Layer Dielectric Gratings

    Institute of Scientific and Technical Information of China (English)

    KONG Wei-Jin; SHEN Zi-Cai; SHEN Jian; SHAO Jian-Da; FAN Zheng-Xiu

    2005-01-01

    @@ We investigate mechanisms of laser induced damage thresholds (LIDTs) of multi-layer dielectric gratings (MDGs).It is found that the laser damage thresholds of MDGs and unstructured dielectric multi-layer coatings (the substrate of MDG) are 3.15J/cm2 and 9.32J/cm2, respectively, at 1064nm (12ns) with the Littrow angle 51.2°and the TEM00 mode. The laser-induced damage mechanism of multi-layer dielectric is presented with the analysis of the following factors: The dominant factor is the pollution on the corrugated surface, which is induced by the complex manufacture process of multi-layer dielectric gratings; another is the electric field distribution along the corrugated surface. The third reason is due to the reduction in stoichiometry of oxide films, resulting from the manufacture process of etching.

  5. Development of time-resolved laser-induced fluorescence spectroscopic technique for the analysis of biomolecules

    Directory of Open Access Journals (Sweden)

    Terzić M.

    2008-01-01

    Full Text Available Our developments of the time-resolved laser-induced fluorescence (TR-LIF detection system for biomolecules are presented. This system is based on the tunable (320 nm to 475 nm Nd:YAG laser pulses used to excite various biomolecules. The detection part is the Streak System for Fluorescence Lifetime Spectroscopy (Hamamatsu, Japan. The system consists of a C4334-01 streakscope, as a detector, DG 535 digital pulse/delay generator, C5094-S Spectrograph and HPD-TA System, as a temporal analyzer. The TR-LIF spectrometer is designed primarily to study the temperature and pressure effects on fluorescence behavior of biomolecules upon excitation with a single nanosecond pulse. The design of this system has capability to combine laser-induced breakdown (LIB with fluorescence, as well to study optodynamic behavior of fluorescence biomolecules.

  6. Time resolved laser-induced breakdown spectroscopy for calcium concentration detection in water

    Institute of Scientific and Technical Information of China (English)

    WU Jiang-lai; LU Yuan; Li Ying; CHENG Kai; GUO Jin-jia; ZHENG Rong-er

    2011-01-01

    @@ The laser induced breakdown spectroscopy (LIBS) is an element analysis technique with the advantages of real time detection, simultaneous multi-element identification, and in-situ and stand-off capacities.To evaluate its potential of ocean applications, in this paper, the time resolved laser-induced breakdown spectroscopy for calcium concentration detection in water is investigated.With the optimum experimental parameters, the plasma emission lifetime is determined to be about 500 ns with 532 nm laser excitation, and 1000 ns with 1064 nm laser excitation.The lowest detection concentration of 50ppm is achieved for calcium detection in CaC12 water solution using the 532 nm LIBS.Even better detection sensitivity is achieved using the 1064 nm LIBS, and the resulted lowest detection concentration of calcium is 25 ppm.The results suggest that it is feasible to develop LIBS as an on-line sensor for metal element monitoring in the sea.

  7. [Laser induced fluorescence spectrum characteristics of common edible oil and fried cooking oil].

    Science.gov (United States)

    Mu, Tao-tao; Chen, Si-ying; Zhang, Yin-chao; Chen, He; Guo, Pan; Ge, Xian-ying; Gao, Li-lei

    2013-09-01

    In order to detect the trench oil the authors built a trench oil rapid detection system based on laser induced fluorescence detection technology. This system used 355 nm laser as excitation light source. The authors collected the fluorescence spectrum of a variety of edible oil and fried cooking oil (a kind of trench oil) and then set up a fluorescence spectrum database by taking advantage of the trench oil detection system It was found that the fluorescence characteristics of fried cooking oil and common edible oil were obviously different. Then it could easily realize the oil recognition and trench oil rapid detection by using principal component analysis and BP neural network, and the overall recognition rate could reach as high as 97.5%. Experiments showed that laser induced fluorescence spectrum technology was fast, non-contact, and highly sensitive. Combined with BP neural network, it would become a new technique to detect the trench oil.

  8. On two optomechanical effects of laser-induced electrostriction in dielectric liquids

    CERN Document Server

    Gojani, Ardian B; Obayashi, Shigeru

    2014-01-01

    This paper presents electrostriction from the phenomenological perspective, and gives details on two mechanical effects arising from laser-matter interaction. Electrostriction is the tendency of materials to compress in the presence of a varying electric field. In this paper, the investigated materials are polar and nonpolar dielectric liquids. It is stressed that the dominant factor is the time evolution of the laser pulse, which causes tensile stresses and acoustic waves. The study is supported by experimental realization of electrostriction, which can be detected only at favourable conditions (observed in water, but not in castor oil). This study will shed light in developing measurement techniques (e.g., laser-induced grating spectroscopy) and in explaining the onset of cavities and laser-induced liquid breakdown.

  9. Crystallo-optic diagnostics method of the soft laser-induced effects in biological fluids

    Science.gov (United States)

    Skopinov, S. A.; Yakovleva, S. V.

    1991-05-01

    Presently, it is well known that individual cells"2 and higher organisms3'4 exhibit a marked response to soft laser irradiation in certain parts of the visible and near infrared spectral ranges. Broad clinical applications of laser therapy and slow progress in understanding of the physical, chemical and biological mechanisms of this phenomenon make the task to search new methods of objectivisation of laser-induces bioeffects very insistent. In this paper we give a short review of the methods of structural-optical diagnostics of the soft laser-induced effects in biofluids (blood and its fractions, saliva, juices, mucuses, exudations, etc.) and suggest their applications in experimental and clinical studies of the soft laser bioeffects.

  10. Laser-induced damage of 1064-nm narrow-band interference filters under different laser modes

    Institute of Scientific and Technical Information of China (English)

    Weidong Gao(高卫东); Hongbo He(贺洪波); Jianda Shao(邵建达); Zhengxiu Fan(范正修)

    2004-01-01

    The laser-induced damage behavior of narrow-band interference filters was investigated with a Nd:YAG laser at 1064 nm under single-pulse mode and free-running laser mode.The absorption measurement of such coatings has been performed by surface thermal lensing(STL)technique.The relationship between damage morphology and absorption under the two different laser modes was studied in detail.The explanation was given by the standing-wave distribution theory.

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

    OpenAIRE

    2014-01-01

    Background: Chordomas are rare malignant tumors that are difficult to treat and have high recurrence rates despite aggressive therapy. Objectives: We present the first case of a patient with a clival chordoma in which complete tumor ablation was achieved using Magnetic Resonance guided Laser Induced Thermal Therapy (LITT) delivered via an endoscopic endonasal approach. We analyzed the safety and feasibility of this approach and quantified the response of this pathology to thermal energy. T...

  12. Pulse temporal compression by two-stage stimulated Brillouin scattering and laser-induced breakdown

    Science.gov (United States)

    Liu, Zhaohong; Wang, Yulei; Wang, Hongli; Bai, Zhenxu; Li, Sensen; Zhang, Hengkang; Wang, Yirui; He, Weiming; Lin, Dianyang; Lu, Zhiwei

    2017-06-01

    A laser pulse temporal compression technique combining stimulated Brillouin scattering (SBS) and laser-induced breakdown (LIB) is proposed in which the leading edge of the laser pulse is compressed using SBS, and the low intensity trailing edge of the laser pulse is truncated by LIB. The feasibility of the proposed scheme is demonstrated by experiments in which a pulse duration of 8 ns is compressed to 170 ps. Higher compression ratios and higher efficiency are expected under optimal experimental conditions.

  13. Laser induced fluorescence applied to studies of particle behaviour in high-temperature plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Muraoka, K.; Uchino, K.; Kajiwara, T.; Maeda, M.; Okada, T. [Kyushu Univ., Fukuoka (Japan)

    1995-03-01

    In this paper, we first review the principle of Laser Induced Fluorescence (LIF), then give an overview of tunable laser sources, the crucial hardware for the experiment, and describe methods of calibration to obtain necessary information from the observed fluorescence, followed by the plasma measurements which have already been conducted. Comments are made for the future perspective of LIF for high-temperature plasma diagnostics. (J.P.N.).

  14. Laser Induced C60 Cage Opening Studied by Semiclassical Dynamics Simulation

    Directory of Open Access Journals (Sweden)

    Yusheng Dou

    2011-01-01

    Full Text Available Laser induced opening of the C60 cage is studied by a semiclassical electron-radiation-ion dynamics technique. The simulation results indicate that the C60 cage is abruptly opened immediately after laser excitation. The opening of the C60 cage induces a quick increase in kinetic energy and a sharp decrease in electronic energy, suggesting that the breaking of the C60 cage efficiently heats up the cluster and enhances the thermal fragmentation of C60 fullerene.

  15. [Application of laser induced breakdown spectroscopy (LIBS) to microdetection of Au film machining].

    Science.gov (United States)

    Yuan, Dong-qing; Zhou, Ming; Shen, Jian; Ren, Nai-fei; Cai, Lan

    2008-10-01

    Film micro-machining is a core in micro- and nano- technology, micro-electro-mechanical systems and photoelectron field. However, it is difficult to control the quality of machining in processing film. In the present paper the authors propose a method to solve this problem by using laser induced breakdown spectroscopy (LIBS). The authors investigated the relation between excitation condition and the quantity of plasma in the process of micro-machining by pulse laser. At low frequency (machining become true.

  16. Analysis of laser-induced fluorescence spectra of in vitro plant tissue cultures

    Science.gov (United States)

    Muñoz-Muñoz, Ana Celia; Gutiérrez-Pulido, Humberto; Rodríguez-Domínguez, José Manuel; Gutiérrez-Mora, Antonia; Rodríguez-Garay, Benjamín; Cervantes-Martínez, Jesús

    2007-04-01

    We demonstrate the effectiveness of laser-induced fluorescence (LIF) for monitoring the development and stress detection of in vitro tissue cultures in a nondestructive and noninvasive way. The changes in LIF spectra caused by the induction of organogenesis, the increase of the F690/F740 ratio as a result of the stress originated in the organogenic explants due to shoot emergence, and the relationship between fluorescence spectra and shoot development were detected by LIF through closed containers of Saintpaulia ionantha.

  17. Laser-induced fluorescence and optical reflection spectra of Japanese natural dyes on silk

    OpenAIRE

    Miyoshi, Tadaki; Matsuda, Yasunori

    1987-01-01

    Fluorescence spectra under nitrogen-laser excitation were measured for silk cloth dyed with Japanese natural dyes. An identification of the dyes on silk was carried out using a laser-induced fluorescence (LIF) technique since dyed cloth has a characteristic fluorescence spectra. Moreover, it is possible to identify dyes on faded cloth and on cloth prepared by a combination dyeing using two kinds of dyes. The LIF technique can identify dyes on cloth which is difficult to identify using the ref...

  18. Determining spatial sodium distribution in fresh and aged bread using laser-induced breakdown spectroscopy

    NARCIS (Netherlands)

    Scholtes-Timmerman, M.; Heddes, C.; Noort, M.W.J.; Veen, S. van

    2013-01-01

    A fast and easy-to-use method using laser-induced breakdown spectroscopy (LIBS) was set up to determine Na (sodium) distribution in baked bread. Standard bread was made using a standard recipe and the amount of salt added was 0, 0.5, 1, 2, 4, 10, 15 and 20g corresponding to 0, 0.25, 0.5, 1.0, 2.0, 5

  19. Determining spatial sodium distribution in fresh and aged bread using laser-induced breakdown spectroscopy

    NARCIS (Netherlands)

    Scholtes-Timmerman, M.; Heddes, C.; Noort, M.W.J.; Veen, S. van

    2013-01-01

    A fast and easy-to-use method using laser-induced breakdown spectroscopy (LIBS) was set up to determine Na (sodium) distribution in baked bread. Standard bread was made using a standard recipe and the amount of salt added was 0, 0.5, 1, 2, 4, 10, 15 and 20g corresponding to 0, 0.25, 0.5, 1.0, 2.0,

  20. Quantitative analysis of pathological nails using laser-induced breakdown spectroscopy (LIBS) technique.

    Science.gov (United States)

    Hamzaoui, S; Khleifia, R; Jaïdane, N; Ben Lakhdar, Z

    2011-01-01

    Laser-induced breakdown spectroscopy (LIBS) has been used as a potential method for simultaneous measurement of the elements Ca, Na, and K, for normal and pathological nails. We compared the measured LIBS spectra of these elements for normal and pathological nails. The B²∑+ --> X²∑+ violet band emission spectrum of CN was used for the estimation of the transient temperature of the plasma plume and consequently of the sample surface considering thermodynamic equilibrium.

  1. Improved algorithm for elemental analysis by laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Kumar, Prashant; Subramanian, K P; Kumar, Ajai; Singh, R K

    2013-07-20

    We propose a calibration-free algorithm for retrieval of elemental concentrations using laser-induced breakdown spectroscopy. This is a simple and improved version of other ratio-based algorithms as it needs only one trial parameter to estimate all other concentrations. The present algorithm has been used to estimate the composition of a brass sample, and the results agree within 1% with electron probe microanalyzer measurements.

  2. Morphology of femtosecond laser-induced structural changes in KTP crystal

    Energy Technology Data Exchange (ETDEWEB)

    Li Yuhua [State Key Lab of Laser Technology and Wuhan National Lab for Optoelectronics, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, Hubei (China); Lu Peixiang [State Key Lab of Laser Technology and Wuhan National Lab for Optoelectronics, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, Hubei (China)]. E-mail: lupeixiang@mail.hust.edu.cn; Dai Nengli [State Key Lab of Laser Technology and Wuhan National Lab for Optoelectronics, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, Hubei (China); Long Hua [State Key Lab of Laser Technology and Wuhan National Lab for Optoelectronics, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, Hubei (China); Wang Ying [State Key Lab of Laser Technology and Wuhan National Lab for Optoelectronics, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, Hubei (China); Yu Benhai [State Key Lab of Laser Technology and Wuhan National Lab for Optoelectronics, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, Hubei (China)

    2006-11-30

    The morphology of structural changes in KTP crystal induced by single femtosecond laser pulse has been investigated by means of CCD camera, scanning electron microscopy (SEM) and atom force microscopy (AFM). The structurally changed region is depressed at energies close to the threshold for producing a structural change and melting ablation morphologies are observed as pulse energy is increased. Furthermore, periodic nanostructures are formed around the edge of the laser-induced spots.

  3. Benefits and applications of laser-induced sparks in real scale model measurements

    DEFF Research Database (Denmark)

    Gómez-Bolaños, Javier; Delikaris-Manias, Symeon; Pulkki, Ville Topias

    2015-01-01

    The characteristics of using a laser-induced spark as a monopole source in scale model measurements were assessed by comparison with an electric spark and a miniature spherical loudspeaker. Room impulse responses of first order directivity sources were synthesized off-line using six spatially dis...... to synthesize room responses of directional sources, e.g., to obtain directional information about reflections inside scale models....

  4. Laser-Induced Continuum Structure of NO Molecules in Two-Colour Femtosecond Pulsed Laser Fields

    Institute of Scientific and Technical Information of China (English)

    WANG Sen-Ming; YUAN Kai-Jun; CONG Shu-Lin

    2006-01-01

    The method of quantum wave packet dynamics is used to study the multiphoton ionization of NO molecules via a two-photon Raman coupling and a laser-induced continuum structure (LICS) state in two-colour strong femtosecond pulsed laser fields.Time-and energy-resolved photoelectron energy spectra are calculated for describing three photoionization channels.The population transfers through the LICS and the Raman coupling passages and discussed.

  5. Atomistic-continuum modeling of ultrafast laser-induced melting of silicon targets

    OpenAIRE

    Lipp, Vladimir

    2015-01-01

    In this work, we present an atomistic-continuum model for simulations of ultrafast laser-induced melting processes in semiconductors on the example of silicon. The kinetics of transient non-equilibrium phase transition mechanisms is addressed with MD method on the atomic level, whereas the laser light absorption, strong generated electron-phonon nonequilibrium, fast heat conduction, and photo-excited free carrier diffusion are accounted for with a continuum TTM-like model (called nTTM). First...

  6. Laser induced surface emission of neutral species and its relationship to optical surface damage processes

    Science.gov (United States)

    Chase, L. L.; Smith, L. K.

    1988-03-01

    The laser-induced emission of neutral constituents and impurities from surfaces of several optical materials is shown to be correlated with optical surface damage thresholds. The characteristics of the emission can be utilized to investigate physical processes involved in the absorption of laser energy at the surface. Examples are given of neutral emission correlated with catastrophic surface heating, changes in surface stoichiometry, and thermally-induced cracking.

  7. Printing Functional 3D Microdevices by Laser-Induced Forward Transfer.

    Science.gov (United States)

    Luo, Jun; Pohl, Ralph; Qi, Lehua; Römer, Gert-Willem; Sun, Chao; Lohse, Detlef; Visser, Claas Willem

    2017-03-01

    Slender, out-of-plane metal microdevices are made in a new spatial domain, by using laser-induced forward transfer (LIFT) of metals. Here, a thermocouple with a thickness of 10 µm and a height of 250 µm, consisting of platinum and gold pillars is demonstrated. Multimaterial LIFT enables manufacturing in the micrometer to millimeter range, i.e., between lithography and other 3D printing technologies. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Time-resolved digital holographic microscopy of laser-induced forward transfer process.

    Science.gov (United States)

    Ma, H; Venugopalan, V

    2014-03-01

    We develop a method for time-resolved digital holographic microscopy to obtain time-resolved 3-D deformation measurements of laser induced forward transfer (LIFT) processes. We demonstrate nanometer axial resolution and nanosecond temporal resolution of our method which is suitable for measuring dynamic morphological changes in LIFT target materials. Such measurements provide insight into the early dynamics of the LIFT process and a means to examine the effect of laser and material parameters on LIFT process dynamics.

  9. Clinical diagnosis of fissure caries with conventional and laser-induced fluorescence techniques

    OpenAIRE

    Chu, C. H.; Lo, E. C. M.; You, D. S. H.

    2010-01-01

    We studied the in vivo validity of dentinal fissure caries diagnosis by visual examination, bitewing radiography, and use of a laser-induced fluorescence device (DIAGNOdent). A total of 144 and second molars with macroscopically intact occlusal surfaces in 41 Chinese young adults were examined visually, by bitewing radiography, and by DIAGNOdent. Visual examination after pit and fissure opening was used as the reference standard. The sensitivity and specificity of detecting caries that had ex...

  10. Photochemical preparation of sub-wavelength heterogeneous laser-induced periodic surface structures.

    Science.gov (United States)

    Kim, Hee-Cheol; Reinhardt, Hendrik; Hillebrecht, Pierre; Hampp, Norbert A

    2012-04-17

    Laser-induced periodic surface structures (LIPSS) are a phenomenon caused by interaction of light with solid surfaces. We present a photochemical concept which uses LIPSS-related light intensity patterns for the generation of heterogeneous nanostructures. The process facilitates arbitrary combinations of substrate and LIPSS-pattern materials. An efficient method for the generation of organometallic hybrid-nanowire arrays on porous anodic aluminum oxide is demonstrated.

  11. Time-resolved measurement of single pulse femtosecond laser-induced periodic surface structure formation

    OpenAIRE

    Kafka, K. R. P.; D. R. Austin; Li, H.; Yi, A; Cheng, J.; Chowdhury, E. A.

    2015-01-01

    Time-resolved diffraction microscopy technique has been used to observe the formation of laser-induced periodic surface structures (LIPSS) from the interaction of a single femtosecond laser pulse (pump) with a nano-scale groove mechanically formed on a single-crystal Cu substrate. The interaction dynamics (0-1200 ps) was captured by diffracting a time-delayed, frequency-doubled pulse from nascent LIPSS formation induced by the pump with an infinity-conjugate microscopy setup. The LIPSS ripple...

  12. Wavelength Dependence of Picosecond Laser-Induced Periodic Surface Structures on Copper

    OpenAIRE

    Maragkaki, Stella; Derrien, Thibault J. -Y.; Levy, Yoann; Bulgakova, Nadezhda M.; Ostendorf, Andreas; Gurevich, Evgeny L.

    2017-01-01

    The physical mechanisms of the laser-induced periodic surface structures (LIPSS) formation are studied in this paper for single-pulse irradiation regimes. The change in the LIPSS period with wavelength of incident laser radiation is investigated experimentally, using a picosecond laser system, which provides 7-ps pulses in near-IR, visible, and UV spectral ranges. The experimental results are compared with predictions made under the assumption that the surface-scattered waves are involved in ...

  13. Assessment of Femtosecond Laser Induced Periodic Surface Structures on Polymer Films

    OpenAIRE

    Rebollar, Esther; Vázquez De Aldana, Javier R.; Martín-Fabiani, Ignacio; Hernández, Margarita; Rueda, Daniel R.; Ezquerra, Tiberio A.; Domingo, Concepción; Moreno, Pablo; Castillejo, Marta

    2013-01-01

    In this work we present the formation of laser induced periodic surface structures (LIPSS) on spin-coated thin films of several model aromatic polymers including poly(ethylene terephthalate), poly(trimethylene terephthalate) and poly carbonate bis-phenol A upon irradiation with femtosecond pulses of 795 and 265 nm at fluences well below the ablation threshold. LIPSS are formed with period lengths similar to the laser wavelength and parallel to the direction of the laser polarization vector. F...

  14. Sub-Diffraction Limited Writing based on Laser Induced Periodic Surface Structures (LIPSS)

    OpenAIRE

    Xiaolong He; Anurup Datta; Woongsik Nam; Traverso, Luis M.; Xianfan Xu

    2016-01-01

    Controlled fabrication of single and multiple nanostructures far below the diffraction limit using a method based on laser induced periodic surface structure (LIPSS) is presented. In typical LIPSS, multiple lines with a certain spatial periodicity, but often not well-aligned, were produced. In this work, well-controlled and aligned nanowires and nanogrooves with widths as small as 40 nm and 60 nm with desired orientation and length are fabricated. Moreover, single nanowire and nanogroove were...

  15. Bio-Inspired Functional Surfaces Based on Laser-Induced Periodic Surface Structures

    OpenAIRE

    Müller, Frank A.; Clemens Kunz; Stephan Gräf

    2016-01-01

    Nature developed numerous solutions to solve various technical problems related to material surfaces by combining the physico-chemical properties of a material with periodically aligned micro/nanostructures in a sophisticated manner. The utilization of ultra-short pulsed lasers allows mimicking numerous of these features by generating laser-induced periodic surface structures (LIPSS). In this review paper, we describe the physical background of LIPSS generation as well as the physical princip...

  16. Successful treatment of laser induced hypopigmentation with narrowband ultraviolet B targeted phototherapy.

    Science.gov (United States)

    Mysore, Venkataram; Anitha, B; Hosthota, Abhineetha

    2013-04-01

    Q-switched 1064 nm neodymium-doped yttrium aluminium garnet (Qs 1064 nm Nd: YAG) laser plays an important role in the treatment of pigmentary skin disorders, including tattoos. Although it has high efficacy and safety, adverse effect like hypopigmentation may occur causing anxiety to patients. We present a case report of Qs 1064 nm Nd: YAG laser induced hypopigmentation which was successfully treated with ultraviolet B targeted phototherapy, with rapid and satisfactory re-pigmentation.

  17. Effect of electron heating on femtosecond laser-induced coherent acoustic phonons in noble metals

    Science.gov (United States)

    Wang, Jincheng; Guo, Chunlei

    2007-05-01

    We employ a surface plasmon technique to resolve the dynamics of femtosecond-laser-induced coherent acoustic phonons in noble metals. Clear acoustic oscillations are observed in our experiments. We further study the dependence of the initial phase of the oscillations on pump fluence, and we find that the initial phase decreases linearly with pump fluence. Our model calculations show that hot electrons instantaneously excited by femtosecond pulses contribute to the generation of coherent acoustic phonons in metals.

  18. Successful treatment of laser induced hypopigmentation with narrowband ultraviolet B targeted phototherapy

    Directory of Open Access Journals (Sweden)

    Venkataram Mysore

    2013-01-01

    Full Text Available Q-switched 1064 nm neodymium-doped yttrium aluminium garnet (Qs 1064 nm Nd: YAG laser plays an important role in the treatment of pigmentary skin disorders, including tattoos. Although it has high efficacy and safety, adverse effect like hypopigmentation may occur causing anxiety to patients. We present a case report of Qs 1064 nm Nd: YAG laser induced hypopigmentation which was successfully treated with ultraviolet B targeted phototherapy, with rapid and satisfactory re-pigmentation.

  19. Analysis Si/Al ratio in zeolites type FAU by laser induced breakdown spectroscopy (LIBS)

    Science.gov (United States)

    Contreras, W. A.; Cabanzo, R.; Mejía-Ospino, E.

    2011-01-01

    In this work, Laser Induced Breakdown Spectroscopy (LIBS) is used to determine the Si/Al ratio of Zeolite type Y. The catalytic activity of zeolite is strongly dependent of the Si/Al ratio. We have used Si lines in the spectral region between 245-265 nm to determine temperature of the plasma generated on pelletized sample of zeolite, and stoichiometry relation between Si and Al.

  20. Water-filled telescopes

    CERN Document Server

    Antonello, E

    2014-01-01

    In this short note we discuss the case of the thought experiments on water-filled telescopes and their realizations during 18th and 19th century. The story of those instruments shows that the scientific progress occurs in a curious way, since there was no stringent reason for the construction of a water-filled telescope.

  1. Analysis of Frozen Sulfate and Chloride Salt Solutions Using Laser-induced Breakdown Spectroscopy Under Martian Conditions

    Science.gov (United States)

    Schröder, S.; Pavlov, S. G.; Hübers, H.-W.; Rauschenbach, I.; Jessberger, E. K.

    2010-03-01

    We showed the feasibility of laser-induced breakdown spectroscopy to analyze different frozen salt solutions under martian conditions. We focused on chloride and sulphate salts which were found on Mars and could lower the freezing point of water.

  2. Plasma diagnostics from self-absorbed doublet lines in laser-induced breakdown spectroscopy

    Science.gov (United States)

    D'Angelo, C. A.; Garcimuño, M.; Díaz Pace, D. M.; Bertuccelli, G.

    2015-10-01

    In this paper, a generalized approach is developed and applied for plasma characterization and quantitative purposes in laser-induced breakdown spectroscopy (LIBS) experiences by employing a selected pair of spectral lines belonging to the same multiplet. It is based on the comparison between experimental ratios of line parameters and the theoretical calculus obtained under the framework of a homogeneous plasma in local thermodynamic equilibrium. The applicability of the method was illustrated by using the atomic resonance transitions 279.55-280.27 nm of Mg II, which are usually detected in laser-induced plasma (LIP) during laser ablation of many kinds of targets. The laser induced plasmas were produced using a Nd:YAG laser from a pressed pellet of powdered calcium hydroxide with a concentration of 300 ppm of Mg. The experimental ratios for peak intensities, total intensities and Stark widths were obtained for different time windows and matched to the theoretical calculus. The temperature and the electron density of the plasma, as well as the Mg columnar density (the atom/ion concentration times the length of the plasma along the line-of-sight), were determined. The results were interpreted under the employed approach.

  3. Time-resolved characterization of laser-induced plasma from fresh potatoes

    Science.gov (United States)

    Lei, Wenqi; Motto-Ros, Vincent; Boueri, Myriam; Ma, Qianli; Zhang, Dacheng; Zheng, Lijuan; Zeng, Heping; Yu, Jin

    2009-09-01

    Optical emission of laser-induced plasma on the surface of fresh vegetables provides sensitive analysis of trace elements for in situ or online detection of these materials. This emergent technique promises applications with expected outcomes in food security or nutrition quality, as well as environment pollution detection. Characterization of the plasma induced on such soft and humid materials represents the first step towards quantitative measurement using this technique. In this paper, we present the experimental setup and protocol that optimize the plasma generation on fresh vegetables, potatoes for instance. The temporal evolution of the plasma properties are investigated using time-resolved laser-induced breakdown spectroscopy (LIBS). In particular, the electron density and the temperatures of the plasma are reported as functions of its decay time. The temperatures are evaluated from the well known Boltzmann and Saha-Boltzmann plot methods. These temperatures are further compared to that of the typical molecular species, CN, for laser-induced plasma from plant materials. This comparison validates the local thermodynamic equilibrium (LTE) in the specific case of fresh vegetables ablated in the typical LIBS conditions. A study of the temporal evolution of the signal to noise ratio also provides practical indications for an optimized detection of trace elements. We demonstrate finally that, under certain conditions, the calibration-free LIBS procedure can be applied to determine the concentrations of trace elements in fresh vegetables.

  4. First results on laser-induced field emission from a CNT-based nanotip

    Energy Technology Data Exchange (ETDEWEB)

    Bionta, M.R. [Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, F-31062 Toulouse (France); CNRS, UMR 5589, F-31062 Toulouse (France); Chalopin, B., E-mail: benoit.chalopin@irsamc.ups-tlse.fr [Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, F-31062 Toulouse (France); CNRS, UMR 5589, F-31062 Toulouse (France); Masseboeuf, A. [CEMES-CNRS, 29 rue Jeanne Marvig, BP 94347, Toulouse, Cedex 4 (France); Chatel, B. [Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, F-31062 Toulouse (France); CNRS, UMR 5589, F-31062 Toulouse (France)

    2015-12-15

    We present the first demonstration of ultrafast laser-induced field emission and measurement of the energy distribution of electrons from a nanotip based on a carbon nanotube (CNT). Our experimental setup extends the studies performed on conventional tungsten or gold tips by using this new innovative tip. The carbon tip consists of concentric carbon layers in the shape of a cone, and has been previously studied as a very good candidate for cold field emission. The first laser-induced field emission from a CNT-based nanotip has been observed and we measured the energy spectrum as well as the polarization dependance of the emission. We also characterize the damage threshold of the tip, when illuminated by a high repetition rate femtosecond laser. These first results are encouraging further studies of electron emission from CNT-based carbon nanotips. - Highlights: • First demonstration of ultrafast-laser induced emission from a CNT based nanotip. • Nanotip consists of concentric carbon layers in the shape of a cone. • Measurements of the energy spectrum and polarization dependence of emission. • Characterization of tip damage threshold.

  5. Determination of the Zinc Concentration in Human Fingernails Using Laser-Induced Breakdown Spectroscopy.

    Science.gov (United States)

    Riberdy, Vlora A; Frederickson, Christopher J; Rehse, Steven J

    2017-04-01

    The absolute concentration of Zn in human fingernail clippings was determined ex vivo using 1064 nm laser-induced breakdown spectroscopy and confirmed by speciated isotope dilution mass spectrometry. A nail testing protocol that sampled across the nail (perpendicular to the direction of growth) was developed and validated by scanning electron microscopy energy-dispersive X-ray spectrometry. Using this protocol, a partial least squares (PLS) regression model predicted the Zn concentration in the fingernails of five people to within an average of 7 ppm. The variation in the Zn concentration with depth into the nail determined by laser-induced breakdown spectroscopy was studied and showed no systematic variation for up to 15 subsequent laser pulses in one location. The effects of nail hydration (dehydrated and over-hydrated) and nail surface roughness were investigated to explain an anomalously large scatter observed in the measurements. This scatter was attributed to the layered nature and fibrous structure of the fingernails, which resulted in non-uniform ablation as determined by scanning electron microscopy. This work demonstrates that a protocol consisting of low pulse energy (laser pulses incident on human fingernail clippings in an Ar environment can produce quantifiable Zn emission in the laser-induced plasma and that the measured Zn intensity can be used to accurately predict the Zn concentration in human fingernails.

  6. Optimization of cavity size for spatial confined laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Su, Xuejiao; Zhou, Weidong; Qian, Huiguo

    2014-11-17

    Spatial confinement with a small cavity is known to enhance the signal intensity of laser-induced breakdown spectroscopy. In this study, the optical emission intensity and signal stability in terms of the relative standard deviation of laser-induced plasmas generated from brass samples with and without the presence of small cylindrical cavities were carefully investigated. The cylindrical cavities were prefabricated by drilling on a set of aluminum plates with variable diameters and heights, which were then placed near the sample surface. Both plasma emission intensity and stability were influenced by cavity diameter and height. With increased cavity diameter from 1.5 mm to 6 mm, the emission intensity of the confined plasma initially increased and then decreased. Furthermore, if a suitable cavity size was selected, both line intensity and stability of the confined plasma emission improved. Based on these observed signal characters with varying cavities, the optimized cavity size for the best signal quality of the laser-induced plasma emission on brass sample was obtained.

  7. [Research Progress on Laser-Induced Breakdown Spectroscopy Based on Resonance Excitation].

    Science.gov (United States)

    Wang, Xu-zhao; Hao, Zhong-qi; Guo, Lian-bo; Li, Xiang-you; Lu, Yong-feng; Zeng, Xiao-yan

    2015-05-01

    Laser-induced breakdown spectroscopy (LIBS), a new kind of atomic spectrum analysis technology, has attracted much atterition of the researchers due to its characteristics of real-time, simultaneous multi-element analysis, and no sample preparation. However, the poor analytical sensitivity has been an important factor that restricts the development of this technology. LIBS based on resonance excitation combines atomic fluorescence spectroscopy and laser-induced breakdown spectroscopy and selectively excites the target elements. In this way, the analytical sensitivity of LIBS can be improved substantially and its application for trace elements detection is greatly expanded. In this paper, the research development of LIBS based on resonance excitation is summarized. The generation of atomic, fluorescence spectrum in laser-induced plasma, the typical classification and the basic principle of LIBS based on resonance. excitation are introduced. The influence of ablation laser energy, resonant laser energy and wavelength, delay between the ablation laser and the resonant laser, and the gate width on spectral enhancement are analyzed in detail. The application status and deficiencies of LIBS based on resonance excitation in the fields of metallurgy, environmental monitoring and isotope detection are elaborated. Future prospects of LIBS based on resonance excitation are also described.

  8. Variational study of the constituents of cholesterol stones by laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Singh, Vivek K; Rai, Vinita; Rai, A K

    2009-01-01

    The major and minor constituents of cholesterol gallstones were investigated by Laser-induced breakdown spectroscopy. The elements detected in the center and in the shell part were calcium (Ca), carbon (C), copper (Cu), hydrogen (H), magnesium (Mg), nitrogen (N), sodium (Na), oxygen (O) and potassium (K), but Cu was absent from the surface of the cholesterol gallstones. Our experimental results revealed that calcium was a major constituent of cholesterol gallstones. Our results also showed that the concentration of Ca, Cu and Mg were large in the center in comparison with the shell. Laser-induced breakdown (LIB) spectra of both portions of the surface (colored part and discolored part) of the cholesterol gallstones were recorded. The concentrations of sodium and potassium were higher in the non-pigmented (colored) part than in the pigmented part (discolored/pigment), which showed that the deficiency of sodium and potassium was playing a key role in the formation of discoloration at the different locations on the outer surfaces of the cholesterol gallstones. Thus, laser-induced breakdown spectroscopy (LIBS) is a suitable technique for the analysis of cholesterol gallstones without any sample preparation.

  9. Time-Resolved Spectroscopy Diagnostic of Laser-Induced Optical Breakdown

    Directory of Open Access Journals (Sweden)

    Christian G. Parigger

    2010-01-01

    Full Text Available Transient laser plasma is generated in laser-induced optical breakdown (LIOB. Here we report experiments conducted with 10.6-micron CO2 laser radiation, and with 1.064-micron fundamental, 0.532-micron frequency-doubled, 0.355-micron frequency-tripled Nd:YAG laser radiation. Characterization of laser induced plasma utilizes laser-induced breakdown spectroscopy (LIBS techniques. Atomic hydrogen Balmer series emissions show electron number density of 1017 cm−3 measured approximately 10 μs and 1 μs after optical breakdown for CO2 and Nd:YAG laser radiation, respectively. Recorded molecular recombination emission spectra of CN and C2 Swan bands indicate an equilibrium temperature in excess of 7000 Kelvin, inferred for these diatomic molecules. Reported are also graphite ablation experiments where we use unfocused laser radiation that is favorable for observation of neutral C3 emission due to reduced C3 cation formation. Our analysis is based on computation of diatomic molecular spectra that includes accurate determination of rotational line strengths, or Hönl-London factors.

  10. Emission enhancement using two orthogonal targets in double pulse laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Ake, C. [Laboratorio de Fotofisica, Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-186, Mexico D.F., C.P. 04510 (Mexico)], E-mail: citlali.sanchez@ccadet.unam.mx; Bolanos, Marduk [Laboratorio de Fotofisica, Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-186, Mexico D.F., C.P. 04510 (Mexico); Ramirez, C.Z. [Colegio de Ciencias y Humanidades Plantel Sur, Universidad Nacional Autonoma de Mexico (Mexico)

    2009-09-15

    The enhancement of emission intensity resulting from the interaction between two laser-induced plasmas on two orthogonal targets was investigated using double pulse laser-induced breakdown spectroscopy (LIBS) at 0.7 Pa, by means of time-resolved spectroscopy and fast photography. The results showed that the interaction between both plasmas improved carbon emission intensity in comparison to a single laser-induced plasma. For all the carbon lines of interest 477.2 nm (CI), 426.7 nm (CII), and 473.4 nm (C{sub 2} Swan band head), the intensity enhancement showed a maximum at a delay between lasers in the range from 2 to 5 {mu}s; moreover it increased with the fluence of the first laser. On the other hand, in the case of C{sub 2} the intensity enhancement reached a maximum at 5 mm from the target; however it decreased with increasing fluence of the second laser. The largest intensity enhancement found was twofold for atomic species and sixfold for molecular species.

  11. Polarization-dependent single-beam laser-induced grating-like effects on titanium films

    Energy Technology Data Exchange (ETDEWEB)

    Camacho-Lopez, Santiago [Departamento de Optica, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Km 107 Carretera Tijuana-Ensenada, Ensenada, Baja California 22860 (Mexico)], E-mail: camachol@cicese.mx; Evans, Rodger [Departamento de Optica, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Km 107 Carretera Tijuana-Ensenada, Ensenada, Baja California 22860 (Mexico); Escobar-Alarcon, Luis [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico DF 11801 (Mexico); Camacho-Lopez, Miguel A. [Facultad de Medicina, Universidad Autonoma del Estado de Mexico, Paseo Tollocan s/n, esq. Jesus Carranza, Toluca, Estado de Mexico 50120 (Mexico); Camacho-Lopez, Marco A. [Facultad de Quimica, Universidad Autonoma del Estado de Mexico, Tollocan s/n, esq. Paseo Colon, Toluca, Estado de Mexico, 50110 (Mexico)

    2008-12-30

    In this paper we present results on polarization-dependent laser-induced effects on titanium (Ti) thin films. We irradiated the titanium films, in ambient air, using a nanosecond Nd:YAG laser (532 nm, 9 ns pulse duration, 10 Hz). Using a series of pulses of fluence well below the ablation threshold, it was possible to form grating-like structures, whose grooves run parallel to the linear polarization of the incident beam. No grating-like structures were obtained when circularly polarized light was used. Our results revealed the remarkable formation of tiny (100 nm and even smaller diameter) craters, which self-arrange quasi-periodically along the ridges (never on the valleys) of the grating-like structure. Optical and scanning electron microscopy were used to study the laser-induced changes on the surface of the titanium films. Micro-Raman spectroscopy was used to analyze the irradiated areas on the titanium films. The Raman analysis demonstrated that the grooves in the grating-like structure, build up from the laser-induced oxidation of titanium. This is the first time, to the best of our knowledge, that periodic surface structures are reported to be induced below the ablation threshold regime, with the grooves made of crystalline metal oxide, in this case TiO{sub 2} in the well-known Rutile phase. The laser irradiated areas on the film acquired selective (upon recording polarization) holographic reflectance.

  12. Discrimination of moist oil shale and limestone using laser induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Paris, P., E-mail: peeter.paris@ut.ee; Piip, K.; Lepp, A.; Lissovski, A.; Aints, M.; Laan, M.

    2015-05-01

    Laser-induced plasma emission spectra of Estonian oil shale and associated limestone with varying moisture content were studied. Time gated spectra excited by 1064 nm laser radiation were recorded. Spectral lines for determination of plasma parameters were selected. Moisture causes the reduction of the intensity of the total emission, and increases the intensity of the H{sub α} line. It was found that the effect of the moisture content on the plasma temperature and electron concentration was inconsiderable. Using the ratio of intensities of H{sub α} and Mg spectral lines, it was possible to distinguish reliably between limestone and oil shale independently of their moisture content. - Highlights: • Laser induced plasma emission spectra of both; Estonian oil shale and limestone with varying moisture content were studied. • The temporal change of the laser induced plasma plume temperature T{sub e} and electron density n{sub e} were evaluated. • Plasma temperature and electron concentration changed with the moisture content inconsiderably. • Limestone and oil shale are distinguished independently of their moisture content by the intensity ratio of H{sub α} and Mg lines.

  13. Stoichiometric changes to KH2PO4 during laser-induced breakdown

    Energy Technology Data Exchange (ETDEWEB)

    Negres, R A; Kucheyev, S O; DeMange, P; Carr, C W; Demos, S G

    2004-11-15

    The local structure of KH{sub 2}PO{sub 4} crystals (so-called KDP) at laser-induced damage sites created by irradiation with {approx} 3-ns, 355-nm laser pulses is studied by a combination of Raman scattering and photoluminescence spectroscopies. We compare spectra from pristine material, surface and bulk laser-induced damage sites, as well as from KPO{sub 3} references. Results show that irradiation with uences above the laser-induced breakdown threshold leads to stoichiometric changes at surface damage sites but not at bulk damage sites. New spectroscopic features are attributed to dehydration products. For the laser irradiation conditions used in this study, the decomposed near-surface layer absorbs photons at {approx} 3.4 eV (364 nm). These results may help explain the recently reported observation that surface laser damage sites in KDP crystals tend to grow with subsequent exposure to high-power laser pulses, while bulk damage sites do not.

  14. Model of laser-induced temperature changes in solid-state optical refrigerators

    Science.gov (United States)

    Patterson, W. M.; Sheik-Bahae, M.; Epstein, R. I.; Hehlen, M. P.

    2010-03-01

    We present an efficient and numerically stable method to calculate time-dependent, laser-induced temperature distributions in solids and provide a detailed description of the computational procedure and its implementation. This study combines the two-dimensional heat equation with laser-induced heat generation and temperature-dependent luminescence. The time-dependent optical response of a system is obtained numerically by the Crank-Nicolson method. This general model is applied to the specific case of optical refrigeration in ytterbium (Yb3+) doped fluorozirconate glass (ZBLAN). The laser-induced temperature change upon optical pumping and the respective transient luminescence response are calculated and compared to experimental data. The model successfully predicts the zero-crossing temperature, the net quantum efficiency, and the functional shape of the transients. We find that the laser-cooling transients have a fast and a slow component that are determined by the excited-state lifetime of the luminescent ion and the thermal properties of the bulk, respectively. The tools presented here may find application in the design of a wide range of optical and optoelectronic devices.

  15. Sensitive elemental detection using microwave-assisted laser-induced breakdown imaging

    Science.gov (United States)

    Iqbal, Adeel; Sun, Zhiwei; Wall, Matthew; Alwahabi, Zeyad T.

    2017-10-01

    This study reports a sensitive spectroscopic method for quantitative elemental detection by manipulating the temporal and spatial parameters of laser-induced plasma. The method was tested for indium detection in solid samples, in which laser ablation was used to generate a tiny plasma. The lifetime of the laser-induced plasma can be extended to hundreds of microseconds using microwave injection to remobilize the electrons. In this novel method, temporal integrated signal of indium emission was significantly enhanced. Meanwhile, the projected detectable area of the excited indium atoms was also significantly improved using an interference-, instead of diffraction-, based technique, achieved by directly imaging microwave-enhanced plasma through a novel narrow-bandpass filter, exactly centered at the indium emission line. Quantitative laser-induce breakdown spectroscopy was also recorded simultaneously with the new imaging method. The intensities recorded from both methods exhibit very good mutual linear relationship. The detection intensity was improved to 14-folds because of the combined improvements in the plasma lifetime and the area of detection.

  16. Preliminary Study of Polymer Removal in 0.25, 0.3, and 0.5 μm Ruthenium Storage Nodes and 0.11 μm, 10.9:1 High-Aspect-Ratio Trenches by Laser-Induced Etching

    Science.gov (United States)

    Kim, Yong-Gi; Cha, Byung Heon

    2005-07-01

    The demands for new etching technology are increasing because of new materials, such as, ruthenium (Ru), platinum (Pt), and iridium (Ir), that are now being used, and the strict critical dimension (C/D) controls required in today’s ultra large scale integrated (ULSI) circuit technology and dynamic random-access memory (DRAM) fabrication lines. Laser etching technology successfully etched organometallic polymers generated after reactive ion etching and ash processing in 0.25, 0.3, and 0.5 μm Ru storage nodes. In this study, the effects of the incident beam profile on the laser-induced etching of the polymers are investigated. Unevenness of the peak energy in the Gaussian beam profile creates unequal etching and heating effects on the polymer removal depending on the irradiating position of the line beam profile on the sample surface. This article discusses for the first time the preliminary results of laser-induced etching with a KrF laser to remove photoresist (PR) and polymer in 0.11 μm deep contact holes with a high-aspect-ratio 10.9:1 trench hole. How deep can the laser etching technology penetrate and strip the PR at a high aspect ratio (A/R) of 10.9:1 and a 0.11 μm hole size? The penetration depth for the PR removal was approximately 1 μm, which is about a 9.1:1 A/R in a 0.11 μm hole with a 1.2-μm-deep trench. Several promising points are discussed on the basis of laser etching in such a high A/R and small 0.11 μm contact hole. Laser-induced etching technology enabled a very uniform penetration depth without any fluctuations, and it also did not show any attack on the edge of the barrier material TiN.

  17. Coronal Holes

    Directory of Open Access Journals (Sweden)

    Steven R. Cranmer

    2009-09-01

    Full Text Available Coronal holes are the darkest and least active regions of the Sun, as observed both on the solar disk and above the solar limb. Coronal holes are associated with rapidly expanding open magnetic fields and the acceleration of the high-speed solar wind. This paper reviews measurements of the plasma properties in coronal holes and how these measurements are used to reveal details about the physical processes that heat the solar corona and accelerate the solar wind. It is still unknown to what extent the solar wind is fed by flux tubes that remain open (and are energized by footpoint-driven wave-like fluctuations, and to what extent much of the mass and energy is input intermittently from closed loops into the open-field regions. Evidence for both paradigms is summarized in this paper. Special emphasis is also given to spectroscopic and coronagraphic measurements that allow the highly dynamic non-equilibrium evolution of the plasma to be followed as the asymptotic conditions in interplanetary space are established in the extended corona. For example, the importance of kinetic plasma physics and turbulence in coronal holes has been affirmed by surprising measurements from the UVCS instrument on SOHO that heavy ions are heated to hundreds of times the temperatures of protons and electrons. These observations point to specific kinds of collisionless Alfvén wave damping (i.e., ion cyclotron resonance, but complete theoretical models do not yet exist. Despite our incomplete knowledge of the complex multi-scale plasma physics, however, much progress has been made toward the goal of understanding the mechanisms ultimately responsible for producing the observed properties of coronal holes.

  18. Two dye combinations suitable for two-color/two-dye laser-induced fluorescence thermography for ethanol

    Science.gov (United States)

    Fenner, Andreas; Stephan, Peter

    2017-06-01

    This paper presents two dye combinations suitable for two-color/two-dye laser-induced fluorescence thermography for ethanol. Besides the temperature dependency of the fluorescence, the influences of laser fluence, dye concentration, pressure, dissolved air, and photobleaching are also discussed. The experimental data are compared with models and data available in literature. Based on this, parameter ranges for two-color/two-dye laser-induced fluorescence thermography applications can be determined.

  19. The effect of laser pulse width on laser-induced damage at K9 and UBK7 components surface

    Science.gov (United States)

    Zhou, Xinda; Ba, Rongsheng; Zheng, Yinbo; Yuan, Jing; Li, Wenhong; Chen, Bo

    2015-07-01

    In this paper, we investigated the effects of laser pulse width on laser-induced damage. We measured the damage threshold of K9 glass and UBK7 glass optical components at different pulse width, then analysis pulse-width dependence of damage threshold. It is shown that damage threshold at different pulse width conforms to thermal restriction mechanism, Because of cm size laser beam, defect on the optical component surface leads to laser-induced threshold decreased.

  20. Measurement of radiative lifetime in atomic samarium using simultaneous detection of laser-induced fluorescence and photoionization signals

    Indian Academy of Sciences (India)

    A C Sahoo; M L Shah; P K Mandal; A K Pulhani; G P Gupta; Vas Dev; B M Suri

    2014-02-01

    In this paper, we report the investigations of lifetime measurement of odd-parity energy level 19009.52 cm-1 of Sm I using simultaneous detection of laser-induced fluorescence and laserinduced photoionization signals employing pump–probe technique. To the best of our knowledge, this is for the first time that the results obtained using laser-induced fluorescence and photoionization techniques have been compared with each other. The obtained results match well with those reported in the literature.

  1. An investigation into the characterisation of the laser-induced incandescence method for the measurement of soot in practical systems

    OpenAIRE

    Grigorian, V.

    2002-01-01

    The thesis describes the characterisation and application of the laser induced incandescence technique for making soot measurements in practical devices. Laser induced incandescence is the phenomenon whereby particulates such a soot absorb laser radiation and are heated to a temperature much higher than the bath gas. The broadband incandescence signal from the hot particles can be detected and the signal is proportional to volume fraction. The technique was used ...

  2. Coronal Holes

    CERN Document Server

    Cranmer, Steven R

    2009-01-01

    Coronal holes are the darkest and least active regions of the Sun, as observed both on the solar disk and above the solar limb. Coronal holes are associated with rapidly expanding open magnetic fields and the acceleration of the high-speed solar wind. This paper reviews measurements of the plasma properties in coronal holes and how these measurements are used to reveal details about the physical processes that heat the solar corona and accelerate the solar wind. It is still unknown to what extent the solar wind is fed by flux tubes that remain open (and are energized by footpoint-driven wave-like fluctuations), and to what extent much of the mass and energy is input intermittently from closed loops into the open-field regions. Evidence for both paradigms is summarized in this paper. Special emphasis is also given to spectroscopic and coronagraphic measurements that allow the highly dynamic non-equilibrium evolution of the plasma to be followed as the asymptotic conditions in interplanetary space are establish...

  3. Filling a Conical Cavity

    Science.gov (United States)

    Nye, Kyle; Eslam-Panah, Azar

    2016-11-01

    Root canal treatment involves the removal of infected tissue inside the tooth's canal system and filling the space with a dense sealing agent to prevent further infection. A good root canal treatment happens when the canals are filled homogeneously and tightly down to the root apex. Such a tooth is able to provide valuable service for an entire lifetime. However, there are some examples of poorly performed root canals where the anterior and posterior routes are not filled completely. Small packets of air can be trapped in narrow access cavities when restoring with resin composites. Such teeth can cause trouble even after many years and lead the conditions like acute bone infection or abscesses. In this study, the filling of dead-end conical cavities with various liquids is reported. The first case studies included conical cavity models with different angles and lengths to visualize the filling process. In this investigation, the rate and completeness at which a variety of liquids fill the cavity were observed to find ideal conditions for the process. Then, a 3D printed model of the scaled representation of a molar with prepared post spaces was used to simulate the root canal treatment. The results of this study can be used to gain a better understanding of the restoration for endodontically treated teeth.

  4. Dumb holes: analogues for black holes.

    Science.gov (United States)

    Unruh, W G

    2008-08-28

    The use of sonic analogues to black and white holes, called dumb or deaf holes, to understand the particle production by black holes is reviewed. The results suggest that the black hole particle production is a low-frequency and low-wavenumber process.

  5. Multidetector CT of pulmonary cavitation: filling in the holes.

    Science.gov (United States)

    Mortensen, K H; Babar, J L; Balan, A

    2015-04-01

    Pulmonary cavitation causes significant morbidity and mortality. Early diagnosis of the presence and aetiology of a cavity is therefore crucial in order to avoid further demise in both the localized pulmonary and systemic disorders that may manifest with pulmonary cavity formation. Multidetector CT has become the principal diagnostic technique for detecting pulmonary cavitation and its complications. This review provides an overview of the aetiologies and their imaging findings using this technique. Combining a literature review with case illustration, a synopsis of the different imaging features and constellations is provided, which may suggest a particular cause and aid the differentiation from diseases with similar findings.

  6. Laser-induced fluorescence reader with a turbidimetric system for sandwich-type immunoassay using nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y.H.; Lim, H.B., E-mail: plasma@dankook.ac.kr

    2015-07-09

    Graphical abstract: Laser-induced fluorescence reader with ratiometric correction for sandwich-type immunoassay using nanoparticles. - Highlights: • Laser-induced fluorescence system with ratiometric correction was developed. • The system reduced experimental error caused by particle loss and aggregation. • The detection limit of about 39 pg mL{sup −1} for salinomycin was obtained. • Calibration linearity and sensitivity were also significantly improved. • The system has the potential for bioanalysis using various nanoparticles. - Abstract: A unique laser-induced fluorescence (LIF) reader equipped with a turbidimetric system was developed for a sandwich-type immunoassay using nanoparticles. The system was specifically designed to reduce experimental error caused by particle loss, aggregation and sinking, and to improve analytical performance through ratiometric measurement of the fluorescence with respect to the turbidimetric absorbance. For application to determine the concentration of salinomycin, magnetic nanoparticles (MNPs) and FITC-doped silica nanoparticles (colored balls) immobilized with antibody were synthesized for magnetic extraction and for tagging as a fluorescence probe, respectively. The detection limit of about 39 pg mL{sup −1} was obtained, which was an improvement of about 2-fold compared to that obtained without employment of the turbidimetric system. Calibration linearity and sensitivity were also improved, with increase from 0.8601 to 0.9905 in the R{sup 2}-coefficient and by 1.92-fold for the curve slope, respectively. The developed LIF reader has the potential to be used for fluorescence measurements using various nanomaterials, such as quantum dots.

  7. Novel estimation of the humification degree of soil organic matter by laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Edilene Cristina, E-mail: edilene@iq.unesp.br [Embrapa Instrumentation, Rua XV de Novembro, 1452, CEP 13560-970 São Carlos, SP (Brazil); São Paulo State University—UNESP, Analytical Chemistry Department, P.O. Box 355, 14801-970 Rua Prof. Francisco Degni, 55, CEP 14800-900 Araraquara, SP (Brazil); Ferreira, Ednaldo José, E-mail: ednaldo.ferreira@embrapa.br [Embrapa Instrumentation, Rua XV de Novembro, 1452, CEP 13560-970 São Carlos, SP (Brazil); Villas-Boas, Paulino Ribeiro, E-mail: paulino.villas-boas@embrapa.br [Embrapa Instrumentation, Rua XV de Novembro, 1452, CEP 13560-970 São Carlos, SP (Brazil); Senesi, Giorgio Saverio, E-mail: giorgio.senesi@ba.imip.cnr.it [Institute of Inorganic Methodologies and Plasmas, CNR, Bari 70126 (Italy); Carvalho, Camila Miranda, E-mail: camilamc@gmail.com [Embrapa Instrumentation, Rua XV de Novembro, 1452, CEP 13560-970 São Carlos, SP (Brazil); Physics Institute of São Carlos, University of São Paulo, IFSC-USP, Av. Trabalhador são-carlense, 400 Pq. Arnold Schimid, 13566-590 São Carlos, SP (Brazil); Romano, Renan Arnon, E-mail: renan.romano@gmail.com [Embrapa Instrumentation, Rua XV de Novembro, 1452, CEP 13560-970 São Carlos, SP (Brazil); Physics Institute of São Carlos, University of São Paulo, IFSC-USP, Av. Trabalhador são-carlense, 400 Pq. Arnold Schimid, 13566-590 São Carlos, SP (Brazil); Martin-Neto, Ladislau, E-mail: ladislau.martin@embrapa.br [Embrapa Instrumentation, Rua XV de Novembro, 1452, CEP 13560-970 São Carlos, SP (Brazil); and others

    2014-09-01

    Soil organic matter (SOM) constitutes an important reservoir of terrestrial carbon and can be considered an alternative for atmospheric carbon storage, contributing to global warming mitigation. Soil management can favor atmospheric carbon incorporation into SOM or its release from SOM to atmosphere. Thus, the evaluation of the humification degree (HD), which is an indication of the recalcitrance of SOM, can provide an estimation of the capacity of carbon sequestration by soils under various managements. The HD of SOM can be estimated by using various analytical techniques including fluorescence spectroscopy. In the present work, the potential of laser-induced breakdown spectroscopy (LIBS) to estimate the HD of SOM was evaluated for the first time. Intensities of emission lines of Al, Mg and Ca from LIBS spectra showing correlation with fluorescence emissions determined by laser-induced fluorescence spectroscopy (LIFS) reference technique were used to obtain a multivaried calibration model based on the k-nearest neighbor (k-NN) method. The values predicted by the proposed model (A-LIBS) showed strong correlation with LIFS results with a Pearson's coefficient of 0.87. The HD of SOM obtained after normalizing A-LIBS by total carbon in the sample showed a strong correlation to that determined by LIFS (0.94), thus suggesting the great potential of LIBS for this novel application. - Highlights: • Humification degree of soil organic matter (HD) • Importance of soil organic matter HD in keeping carbon in soil • Laser induced fluorescence spectroscopy (LIFS) for HD estimation (reference method) • New LIBS application to predict HD.

  8. Influence of exothermic chemical reactions on laser-induced shock waves.

    Science.gov (United States)

    Gottfried, Jennifer L

    2014-10-21

    Differences in the excitation of non-energetic and energetic residues with a 900 mJ, 6 ns laser pulse (1064 nm) have been investigated. Emission from the laser-induced plasma of energetic materials (e.g. triaminotrinitrobenzene [TATB], cyclotrimethylene trinitramine [RDX], and hexanitrohexaazaisowurtzitane [CL-20]) is significantly reduced compared to non-energetic materials (e.g. sugar, melamine, and l-glutamine). Expansion of the resulting laser-induced shock wave into the air above the sample surface was imaged on a microsecond timescale with a high-speed camera recording multiple frames from each laser shot; the excitation of energetic materials produces larger heat-affected zones in the surrounding atmosphere (facilitating deflagration of particles ejected from the sample surface), results in the formation of additional shock fronts, and generates faster external shock front velocities (>750 m s(-1)) compared to non-energetic materials (550-600 m s(-1)). Non-explosive materials that undergo exothermic chemical reactions in air at high temperatures such as ammonium nitrate and magnesium sulfate produce shock velocities which exceed those of the inert materials but are less than those generated by the exothermic reactions of explosive materials (650-700 m s(-1)). The most powerful explosives produced the highest shock velocities. A comparison to several existing shock models demonstrated that no single model describes the shock propagation for both non-energetic and energetic materials. The influence of the exothermic chemical reactions initiated by the pulsed laser on the velocity of the laser-induced shock waves has thus been demonstrated for the first time.

  9. LASER-INDUCED DECOMPOSITION OF METAL CARBONYLS FOR CHEMICAL VAPOR DEPOSITION OF MICROSTRUCTURES

    OpenAIRE

    1989-01-01

    Tungsten and nickel carbonyls were used to produce metal microstructures by laser-induced chemical vapor deposition (CVD) on various substrates. The deposition rate of microstructures produced by thermodecomposition of W(CO)6 on Si substrates heated with a cw Ar+ laser beam was relatively low (10 to 30 nm/s) even at high temperatures (above 900°C). Ni microstructures were deposited on quartz substrates irradiated with a CO2 laser beam. Relatively high laser powers were needed to heat the Ni s...

  10. Experimental Research of Reliability of Plant Stress State Detection by Laser-Induced Fluorescence Method

    Directory of Open Access Journals (Sweden)

    Yury Fedotov

    2016-01-01

    Full Text Available Experimental laboratory investigations of the laser-induced fluorescence spectra of watercress and lawn grass were conducted. The fluorescence spectra were excited by YAG:Nd laser emitting at 532 nm. It was established that the influence of stress caused by mechanical damage, overwatering, and soil pollution is manifested in changes of the spectra shapes. The mean values and confidence intervals for the ratio of two fluorescence maxima near 685 and 740 nm were estimated. It is presented that the fluorescence ratio could be considered a reliable characteristic of plant stress state.

  11. Modeling of laser-induced damage and optic usage at the National Ignition Facility

    Science.gov (United States)

    Liao, Zhi M.; Nostrand, Mike; Carr, Wren; Bude, Jeff; Suratwala, Tayyab I.

    2016-07-01

    Modeling of laser-induced optics damage has been introduced to benchmark existing optic usage at the National Ignition Facility (NIF) which includes the number of optics exchanged for damage repair. NIF has pioneered an optics recycle strategy to allow it to run the laser at capacity since fully commissioned in 2009 while keeping the cost of optics usage manageable. We will show how the damage model is being used to evaluate strategies to streamline our optics loop efficiency, as we strive to increase the laser shot rate without increasing operating costs.

  12. Design of sonar transducer based on the laser-induced sound

    Institute of Scientific and Technical Information of China (English)

    WANG Yuhong; WANG Jiangan; ZONG Siguang; WU Ronghua

    2009-01-01

    A design of a kind of sonar transducers was presented. An experimental system was developed for producing the sound signal based on the laser-induced breakdown and bubble oscillation. The power spectrum and the ambiguity function were analyzed. The range resolu-tion and the Doppler resolution constant of the sound signal were determined. It is basically proved in theory that both the range resolution and directivity of the sonar transducer are very high. The transducer can be a sound source of high-resolution sonars.

  13. Laser-induced fusion of human embryonic stem cells with optical tweezers

    Energy Technology Data Exchange (ETDEWEB)

    Chen Shuxun; Wang Xiaolin; Sun Dong [Department of Mechanical and Biomedical Engineering, City University of Hong Kong (Hong Kong); Cheng Jinping; Han Cheng, Shuk [Department of Biology and Chemistry, City University of Hong Kong (Hong Kong); Kong, Chi-Wing [Stem Cell and Regenerative Medicine Consortium, and Departments of Medicine and Physiology, LKS Faculty of Medicine, University of Hong Kong (Hong Kong); Li, Ronald A. [Stem Cell and Regenerative Medicine Consortium, and Departments of Medicine and Physiology, LKS Faculty of Medicine, University of Hong Kong (Hong Kong); Center of Cardiovascular Research, Mount Sinai School of Medicine, New York, New York 10029 (United States)

    2013-07-15

    We report a study on the laser-induced fusion of human embryonic stem cells (hESCs) at the single-cell level. Cells were manipulated by optical tweezers and fused under irradiation with pulsed UV laser at 355 nm. Successful fusion was indicated by green fluorescence protein transfer. The influence of laser pulse energy on the fusion efficiency was investigated. The fused products were viable as gauged by live cell staining. Successful fusion of hESCs with somatic cells was also demonstrated. The reported fusion outcome may facilitate studies of cell differentiation, maturation, and reprogramming.

  14. Laser-induced absorption and fluorescence studies of photochromic Schiff bases

    DEFF Research Database (Denmark)

    Kownacki, K.; Mordzinski, A.; Wilbrandt, R.

    1994-01-01

    Three photochromic Schiff bases: N-salicylideneaniline (SA), N-salicylidene-1-naphthylamine (SN), and N,N-bis-(salicylidene)-p-phenylenediamine (Bsp), were studied in acetonitrile by means of steady-state and time-resolved absorption and fluorescence spectroscopy, as well as semiempirical quantum...... chemical calculations. In all these molecules, the transient absorption and two-step laser-induced fluorescence spectra of long-lived transients are remarkably similar. The photochromic species is tentatively assigned to the non-hydrogen bonded form of the proton transfer reaction product...

  15. Field Observations with Laser-Induced Fluorescence Transient (LIFT Method in Barley and Sugar Beet

    Directory of Open Access Journals (Sweden)

    Anna R. Raesch

    2014-05-01

    Full Text Available The laser-induced fluorescence transient (LIFT method is a non-invasive remote sensing technique for measurement of photosynthetic performance of plants under laboratory and field conditions. We report here a long-term comparative study to monitor the performance of different cultivars of barley and sugar beet during the growth season of these crops. The LIFT measurements provided useful results about photosynthetic light use efficiency on selected leaves in the canopy of the studied crops. The different canopy architectures, with different optical properties, influenced the LIFT measurements.

  16. Laser-induced thermal dynamics and temperature localization phenomenon in tissues and cells doped with nanoshells

    Science.gov (United States)

    Yakunin, Alexander N.; Avetisyan, Yury A.; Tuchin, Valery V.

    2012-03-01

    Paper presents and discusses the features of laser-induced thermal dynamics of the gold nanoshells, which is associated with their relatively large size and layered structure. Unlike bulk nanoparticles the existence of a novel thermal phenomenon - hoop-shaped narrow hot zone on the nanoshell surface - is found. It is caused by spatial-temporal inhomogeneities of light field diffracted by a nanoshell and corresponding absorption of laser radiation. The numerical solution of time-dependent heat conduction equation accounting for corresponding spatially inhomogeneous distribution of heating sources is presented.

  17. Novel xenon calibration scheme for two-photon absorption laser induced fluorescence of hydrogen

    Science.gov (United States)

    Elliott, Drew; Scime, Earl; Short, Zachary

    2016-11-01

    Two photon absorption laser induced fluorescence (TALIF) measurements of neutral hydrogen and its isotopes are typically calibrated by performing TALIF measurements on krypton with the same diagnostic system and using the known ratio of the absorption cross sections [K. Niemi et al., J. Phys. D 34, 2330 (2001)]. Here we present the measurements of a new calibration method based on a ground state xenon scheme for which the fluorescent emission wavelength is nearly identical to that of hydrogen, thereby eliminating chromatic effects in the collection optics and simplifying detector calibration. We determine that the ratio of the TALIF cross sections of xenon and hydrogen is 0.024 ± 0.001.

  18. Femtosecond Laser-Induced Breakdown Spectroscopy for Detection of Trace Elements in Sophora Leaves

    Institute of Scientific and Technical Information of China (English)

    Myriam Bossu; HAO Zuo-Qiang; Matthieu Baudelet; YU Jia; ZHANG Zhe; ZHANG Jie

    2007-01-01

    Sophora leaves from several areas in Beijing are analysed by femtoeecond laser-induced breakdown spectroscopy (femto-LIBS).AIthough the used spectral detection systemis not time-resolved,thespectral lines of trace mineral elements are detected and anallyed.It is proven that the femto-LIBS can be an effcient method to detect mineral trace elements contained in tree leaves which is a biomonitor for atmospheric pollution assessment or botanic studies.An interesting case of correlation between trace elements detected in tree leaves and the pollution of the concerned area is presented,for the first time to our knowledge.

  19. Optical tuning of near and far fields form hybrid dimer nanoantennas via laser-induced melting

    Science.gov (United States)

    Kolodny, Stanislav A.; Sun, Yali; Zuev, Dmitry A.; Makarov, Sergey V.; Krasnok, Alexander E.; Belov, Pavel A.

    2016-08-01

    Hybrid nanophotonics based on metal-dielectric nanostructures unifies the advantages of plasmonics and all-dielectric nanophotonics providing strong localization of light, magnetic optical response and specifically designed scattering properties. Here, we propose a new method for optical properties tuning of hybrid dimer nanoantenas via laser-induced melting at the nanoscale. We demonstrate numerically that near- and farfield properties of a hybrid nanoantenna dramatically changes with fs-laser modification of Au particle. The results lay the groundwork for the fine-tuning of hybrid nanoantennas and can be applied for effective light manipulation at the nanoscale, as well as biomedical and energy applications.

  20. Fabrication and characteristics of self-assembly nano-polystyrene films by laser induced CVD

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Tingting [Department of Applied Physics, Chongqing University, Chongqing 401331 (China); Science and Technology on Plasma Physics Laboratory, Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Cai, Congzhong [Department of Applied Physics, Chongqing University, Chongqing 401331 (China); Peng, Liping [Science and Technology on Plasma Physics Laboratory, Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Wu, Weidong, E-mail: wuweidongding@163.com [Science and Technology on Plasma Physics Laboratory, Research Center of Laser Fusion, CAEP, Mianyang 621900 (China)

    2013-10-01

    The self-assembly nano-polystyrene (PS) films have been prepared by laser induced CVD at room temperature. The XPS, Raman and UV–vis absorption spectra all indicated that the films were PS. The optical properties, microstructure and controllable nanostructure of PS films have been investigated. Dewetting-like microstructure in PS films was investigated and uniform island structures with a diameter of about 200 nm were observed at the deposition pressure of 14 Pa. The films possess good toughness and precisely controlled thicknesses. The free-standing PS films with thickness of 10 nm could be obtained by this method though a series of process.

  1. Laser-Induced Damage Growth on Larger-Aperture Fused Silica Optical Components at 351 nm

    Institute of Scientific and Technical Information of China (English)

    HUANG Wan-Qing; ZHANG Xiao-Min; HAN Wei; WANG Fang; XIANG Yong; LI Fu-Quan; FENG Bin; JING Feng; WEI Xiao-Feng; ZHENG Wan-Guo

    2009-01-01

    Laser-induced damage is a key lifetime limiter for optics in high-power laser facility. Damage initiation and growth under 351 nm high-fluence laser irradiation are observed on larger-aperture fused silica optics. The input surface of one fused silica component is damaged most severely and an explanation is presented. Obscurations and the area of a scratch on it are found to grow exponentially with the shot number. The area of damage site grows linearly. Micrographs of damage sites support the micro-explosion damage model which could be used to qualitatively explain the phenomena.

  2. Trace Detection of Metastable Helium Molecules in Superfluid Helium by Laser-Induced Fluorescence

    CERN Document Server

    McKinsey, D N; Nikkel, J A; Rellergert, W

    2005-01-01

    We describe an approach to detecting ionizing radiation that combines the special properties of superfluid helium with the sensitivity of quantum optics techniques. Ionization in liquid helium results in the copious production of metastable helium molecules, which can be detected by laser-induced fluorescence. Each molecule can be probed many times using a cycling transition, resulting in the detection of individual molecules with high signal to noise. This technique could be used to detect neutrinos, weakly interacting massive particles, and ultracold neutrons, and to image superfluid flow in liquid He-4.

  3. Change in refractive index of muscle tissue during laser-induced interstitial thermotherapy.

    Science.gov (United States)

    Chen, Na; Chen, Meimei; Liu, Shupeng; Guo, Qiang; Chen, Zhenyi; Wang, Tingyun

    2014-01-01

    This paper presents a long-period fiber-grating (LPG) based Michelson interferometric refractometry to monitor the change in refractive index of porcine muscle during laser-induced interstitial thermotherapy (LITT). As the wavelength of RI interferometer alters with the change in refractive index around the probe, the LPG based refractometry is combined with LITT system to measure the change in refractive index of porcine muscle when irradiated by laser. The experimental results show the denaturation of tissue alters the refractive index significantly and the LPG sensor can be applied to monitor the tissue state during the LITT.

  4. Low power continuous wave laser induced optical nonlinearities in saffron ( Crocus Sativus L.)

    Science.gov (United States)

    Nasibov, H.; Mamedbeili, I.

    2010-12-01

    We report on the low power CW laser induced nonlinear optical responses of Saffron (stigmata of Crocus Savitus L.) ethanol and methanol extracts. The optical nonlinearities were investigated by performing Z-scan measurements at 470 and 535 nm wavelengths. At both wavelengths the material has a strong nonlinear refraction, mainly of thermal origin. However, only at 470 nm wavelength the material exhibit pronounced saturable nonlinear absorption. Long-term (70 days) stability measurements indicated that the nonlinearities in the Saffron extracts are due to their nonvolatile components. This study shows that there is great potential for Saffron extracts to be used in nonlinear photonic applications.

  5. Laser ablation of powdered samples and analysis by means of laser-induced breakdown spectroscopy

    Science.gov (United States)

    Ctvrtnickova, T.; Cabalin, L.; Laserna, J.; Kanicky, V.; Nicolas, G.

    2009-03-01

    The presented work proves the capacities of laser-induced breakdown spectroscopy (LIBS) as a fast, universal, and versatile technique for analysis of complex materials as ceramics. This paper reports on the analysis of ceramic raw materials (brick clays and kaolin) submitted to laser ablation in the form of pressed pellets. Spectrographic study was provided by standard single-pulse LIBS technique and orthogonal reheating double-pulse LIBS. It was found that both methods are comparable in terms of analytical performance, if adequate experimental parameters and signal detection systems are used.

  6. [INVITED] Laser-induced forward transfer: A high resolution additive manufacturing technology

    Science.gov (United States)

    Delaporte, Philippe; Alloncle, Anne-Patricia

    2016-04-01

    Among the additive manufacturing techniques, laser-induced forward transfer addresses the challenges of printing thin films in solid phase or small volume droplets in liquid phase with very high resolution. This paper reviews the physics of this process and explores the pros and cons of this technology versus other digital printing technologies. The main field of applications are printed electronics, organic electronics and tissue engineering, and the most promising short terms ones concern digital laser printing of sensors and conductive tracks. Future directions and emerging areas of interest are discussed such as printing solid from a liquid phase and 3D digital nanomanufacturing.

  7. Fabrication of "petal effect" surfaces by femtosecond laser-induced forward transfer

    Science.gov (United States)

    Li, Hong-Jin; Fan, Wen-Zhong; Pan, Huai-Hai; Wang, Cheng-Wei; Qian, Jing; Zhao, Quan-Zhong

    2017-01-01

    Superhydrophobic adhesive glass surfaces with polystyrene has been obtained via femtosecond laser induced forward transfer (LIFT). Using this facile method, we obtained composite structures on the glass surface, achieving the transformation from hydrophilicity to superhydrophobicity with contact angle from 36.22° on the glass surface to 159.19° on the LIFT modified glass surface. Analogous to the "petal effect", the obtained superhydrophobic surface also shows high adhesion. Furthermore, the wettability of LIFT modified glass surface can be tuned by changing the interval width of laser scanning, which can be explained by the Cassie impregnating wetting model.

  8. Extraction of selectively ionised atomic isotopes from a laser-induced plasma

    Energy Technology Data Exchange (ETDEWEB)

    Arisawa, T.; Suzuki, Y.; Maruyama, Y.; Shiba, K. (Japan Atomic Energy Research Inst., Tokai, Ibaraki. Tokai Research Establishment)

    1982-10-14

    A laser-induced plasma of alkali atoms was studied with a view to efficient recovery of isotope ions, with small charge exchange losses. The electron temperature was measured by the double-probe method for several kinds of excitation schemes, which gave the relationship between temperature and the energy given to ions by laser photons. A charge exchange process between lithium isotopes was also studied in an electromagnetic field. It was shown that optimum electrostatic and magnetic field strength exist which maximise the 'separative power'.

  9. Laser-induced breakdown spectroscopy for real time and online elemental analysis

    CERN Document Server

    Rai, V N; Yueh, Fang-Yu; Singh, J P

    2014-01-01

    Laser-induced breakdown spectroscopy (LIBS) is a laser based diagnostics used to study atomic emission from the expanding plasma plume formed during the laser-matter interaction. It provides valuable information about the composition of the target material. LIBS has proved its potential application in the analysis of impurities, pollutants and toxic elements in various types of matrices of different samples (solid, liquid and gases), even those present under difficult and harsh environmental conditions. This article reviews some recent developments in the field, and its wide application in various fields of research and analysis.

  10. Optical-fiber-based laser-induced breakdown spectroscopy for detection of early caries

    Science.gov (United States)

    Sasazawa, Shuhei; Kakino, Satoko; Matsuura, Yuji

    2015-06-01

    A laser-induced breakdown spectroscopy (LIBS) system targeting for the in vivo analysis of tooth enamel is described. The system is planned to enable real-time analysis of teeth during laser dental treatment by utilizing a hollow optical fiber that transmits both Q-switched Nd:YAG laser light for LIBS and infrared Er:YAG laser light for tooth ablation. The sensitivity of caries detection was substantially improved by expanding the spectral region under analysis to ultraviolet (UV) light and by focusing on emission peaks of Zn in the UV region. Subsequently, early caries were distinguished from healthy teeth with accuracy rates above 80% in vitro.

  11. Laser-Induced Electron Diffraction: Inversion of Photoelectron Spectra for Molecular Orbital Imaging

    CERN Document Server

    Puthumpally-Joseph, R; Peters, M; Nguyen-Dang, T T; Atabek, O; Charron, E

    2016-01-01

    In this paper, we discuss the possibility of imaging molecular orbitals from photoelectron spectra obtained via Laser Induced Electron Diffraction (LIED) in linear molecules. This is an extension of our work published recently in Physical Review A \\textbf{94}, 023421 (2016) to the case of the HOMO-1 orbital of the carbon dioxide molecule. We show that such an imaging technique has the potential to image molecular orbitals at different internuclear distances in a sub-femtosecond time scale and with a resolution of a fraction of an Angstr\\"om.

  12. Effects of Laser-Induced Heating on the Photoinduced Birefringence in Azobenzene-Side-Chain Copolymer

    Institute of Scientific and Technical Information of China (English)

    杨军; 明海; 章江英; 王沛; 郎建英; 鲁拥华; 刘剑; 张其锦

    2003-01-01

    The photoinduced birefringence was observed in the polymer poly[2-(4-(4-cyanophenyl) diazenyl phenyloxy) ethoxyl methacrylatel with a cw 532nm laser. The azobenzene polymer character has been studied under the conditions of various illuminating time and light intensities. By analysing the processes of reorientation, the effect of laser-induced heating has been introduced to the buildup of photoinduced birefringence in azobenzene-side-chain copolymer. The curves for the buildup of birefringence were fitted with a modified function, i.e., biexponential curves and Gaussian curves. The relationship among all the parameters has also been presented. With the modified fitting function, we obtain a better fitting result.

  13. Activation analysis of indium, KCl, and melamine by using a laser-induced neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sungman; Lee, Kitae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Cha, Hyungki [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2014-04-15

    A laser-induced repetitively operated fast neutron source with a neutron yield of 4 x 10{sup 5} n/pulse and a pulse repetition rate of 5 Hz, which was developed using a deuterated polystyrene film target and a 24-TW femtosecond laser, was applied for laser activation analyses of indium, KCl, and melamine samples. The nuclear reactions of the measured gamma spectra for the activated samples were identified as (n, γ), (n, n'), and (n, 2n) reactions. These indicate possible usage of the neutron source for practical activation analyses of various materials.

  14. Rapid Analysis of Energetic and Geo-Materials Using Laser Induced Breakdown Spectroscopy

    Science.gov (United States)

    2013-04-01

    Anal (2005) 5, 21. 20. Anzano, J. M., et al., Anal Chim Acta (2006) 575, 230. 21. Rusak, D. A., et al., TrAC Trend Anal Chem (1998) 17, 453. 22. Martin ...Spectrosc Reviews (2004) 39, 27. 25. Winefordner, J. D., et al., J Anal Atom Spectrom (2004) 19, 1061. 26. Cremers , D. A., and Radziemski, L. J., Handbook...29. Singh, J. P. and Thakur, S. N., Eds., Laser-Induced Breakdown Spectroscopy, Elsevier: Amsterdam, The Netherlands, 2007. 30. Cremers , D. A., and

  15. Laser-Induced Optical Breakdown in Methane: Diagnostic Using H-Gamma Line Broadening

    Directory of Open Access Journals (Sweden)

    Christian G. Parigger

    2010-01-01

    Full Text Available Measurements and analysis are reported of Stark-broadened profiles of the H-gamma line emitted from plasma formed by Laser-Induced Optical Breakdown (LIOB in a pulsed methane flow. Electron densities Ne are deduced for 18 instants of time in the range between 0.4 and 2.1 microseconds after LIOB and for 2 different gas pressures. The obtained values of Ne are in a good agreement with the corresponding values found previously from Stark-broadened profiles of the H-alpha and H-beta lines.

  16. Detection of lead in paint samples synthesized locally using-laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Gondal, Mohammed A; Nasr, Mohamed M; Ahmed, Mubarak M; Yamani, Zain H; Alsalhi, M S

    2011-01-01

    A laser-induced breakdown spectroscopy (LIBS) setup was developed to detect lead and other toxic contaminants such as chromium in paint emulsion samples manufactured in Saudi Arabia. The lead concentration detected in these samples was in the 327.2-755.3 ppm range, which is much higher than the safe permissible limit set by Saudi regulatory agencies. Similarly, chromium concentration (98.1-149.5 ppm) was found in high concentrations as well. The results obtained with our LIBS setup are comparable with the sample analysis utilizing a standard technique such as ICP, and our LIBS results are comparable to ICP with in an accuracy limit of 2-4 %.

  17. Use of laser-induced breakdown spectroscopy for the differentiation of pathogens and viruses on substrates.

    Science.gov (United States)

    Multari, Rosalie A; Cremers, David A; Bostian, Melissa L

    2012-03-01

    In this work, the use of laser-induced breakdown spectroscopy (LIBS) to differentiate live pathogens and killed viruses on substrates is investigated. Live pathogens B. anthracis Sterne strain and F. tularensis live vaccine strain were interrogated as lawn and colonies on agar; dilutions on agar; and dilutions on glass slides, and it was found possible to differentiate among all samples. UV killed hantavirusstrains were studied as dilutions on slides and it was also found possible to differentiate among strains. To the best of our knowledge, this is the first study in which LIBS has been used to differentiate virus samples. © 2012 Optical Society of America

  18. Optical-fiber-based laser-induced breakdown spectroscopy for detection of early caries.

    Science.gov (United States)

    Sasazawa, Shuhei; Kakino, Satoko; Matsuura, Yuji

    2015-06-01

    A laser-induced breakdown spectroscopy (LIBS) system targeting for the in vivo analysis of tooth enamel is described. The system is planned to enable real-time analysis of teeth during laser dental treatment by utilizing a hollow optical fiber that transmits both Q-switched Nd:YAG laser light for LIBS and infrared Er:YAG laser light for tooth ablation. The sensitivity of caries detection was substantially improved by expanding the spectral region under analysis to ultraviolet (UV) light and by focusing on emission peaks of Zn in the UV region. Subsequently, early caries were distinguished from healthy teeth with accuracy rates above 80% in vitro.

  19. Laser-induced breakdown spectroscopy determination of toxic metals in fresh fish.

    Science.gov (United States)

    Ponce, L V; Flores, T; Sosa-Saldaña, M; Alvira, F C; Bilmes, G M

    2016-01-10

    A method based on laser induced breakdown spectroscopy (LIBS) for monitoring lead and copper accumulation in edible fish, particularly "tilapia del Nilo" (Oreochromis niloticus) is presented. The capability of this analytical method is compared with results obtained by atomic absorption spectrometry. Detection limits by LIBS are 25 parts per million (ppm) for Pb and 100 ppm for Cu, values that are below the maximum permissible levels of some international standards. Application of LIBS detection allows the development of portable instruments for contamination control of edible fish.

  20. Laser-induced rotation of iodine molecules in He-nanodroplets

    DEFF Research Database (Denmark)

    Shepperson, Benjamin; Søndergaard, Anders A.; Christiansen, Lars

    2017-01-01

    Rotation of molecules embedded in He nanodroplets is explored by a combination of fs laser-induced alignment experiments and angulon quasiparticle theory. We demonstrate that at low fluence of the fs alignment pulse, the molecule and its solvation shell can be set into coherent collective rotation...... lasting long enough to form revivals. With increasing fluence, however, the revivals disappear -- instead, rotational dynamics as rapid as for an isolated molecule is observed during the first few picoseconds. Classical calculations trace this phenomenon to transient decoupling of the molecule from its He...

  1. Theoretical study of determining orientation and alignment of symmetric top molecule using laser-induced fluorescence

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    General expressions used for extracting the orientation and alignment parameters of a symmetric top molecule from laser-induced fluorescence (LIF) intensity are derived by employing the density matrix approach. The molecular orientation and alignment are described by molecular state multipoles. Excitation and detection are circularly and linearly polarized lights, respectively. In general cases, the LIF intensity is a complex function of the initial molecular state multipoles, the dynamic factors and the excitation-detection geometrical factors. It contains a population, ten orientation and fourteen alignment multipoles. The problem of how to extract the initial molecular state multipoles from the resolved LIF intensity is discussed.

  2. Containerless laser-induced flourescence study of vaporization and optical properties for sapphire and alumina

    Science.gov (United States)

    Nordine, Paul C.; Schiffman, Robert A.

    1988-01-01

    Evaporation of aluminum oxide was studied from 1800 to 2327 K by laser-induced flourescence (LIF) detection of Al atom vapor over sapphire and alumina spheres that were levitated in an argon gas jet and heated with a continuous wave CO2 laser. Optical properties were determined from apparent specimen temperatures measured with an optical pyrometer and true temperatures deduced from the LIF intensity versus temperature measurements using the known temperature dependence of the Al atom vapor concentration in equilibrium with Al2O3. The effects of impurities and dissolved oxygen on the high-temperature optical properties of aluminum oxide were discussed.

  3. Single microchannel high-temperature fiber sensor by femtosecond laser-induced water breakdown.

    Science.gov (United States)

    Liu, Yi; Qu, Shiliang; Li, Yan

    2013-02-01

    Single microchannel high-temperature fiber sensors were fabricated by drilling a microchannel across the fiber core near the end of the common single-mode fiber using femtosecond laser-induced water breakdown. Then the microchannel was annealed by the arc discharge to smooth its inwall. The two sides of microchannel and the end surface of the fiber constitute three reflective mirrors, which form a three-wave Fabry-Pérot interferometer (FPI). The fabricated FPI can be used as a high-temperature sensor in harsh environments due to its large temperature range (up to 1000°C), high linearity, miniaturized size, and perfect mechanical property.

  4. Laser-induced incandescence of suspended particles as a source of excitation of dye luminescence

    CERN Document Server

    Zelensky, S

    2003-01-01

    The interaction of pulsed YAG-Nd sup 3 sup + laser radiation with submicron light-absorbing particles suspended in an aqueous solution of Rhodamine 6G is investigated experimentally. The experiments demonstrate that the laser-induced incandescence of suspended particles excites the luminescence of the dissolved dye molecules. The mechanism of the luminescence excitation consists in the reabsorption of the thermal radiation within the volume of the sample cell. On the ground of this mechanism of excitation, a method of measurement of the luminescence quantum yield is proposed and realized. The method requires the knowledge of the geometrical parameters of the cell and does not require the use of reference samples.

  5. Discrimination of moist oil shale and limestone using laser induced breakdown spectroscopy

    Science.gov (United States)

    Paris, P.; Piip, K.; Lepp, A.; Lissovski, A.; Aints, M.; Laan, M.

    2015-05-01

    Laser-induced plasma emission spectra of Estonian oil shale and associated limestone with varying moisture content were studied. Time gated spectra excited by 1064 nm laser radiation were recorded. Spectral lines for determination of plasma parameters were selected. Moisture causes the reduction of the intensity of the total emission, and increases the intensity of the Hα line. It was found that the effect of the moisture content on the plasma temperature and electron concentration was inconsiderable. Using the ratio of intensities of Hα and Mg spectral lines, it was possible to distinguish reliably between limestone and oil shale independently of their moisture content.

  6. Double-pulse standoff laser-induced breakdown spectroscopy for versatile hazardous materials detection

    Energy Technology Data Exchange (ETDEWEB)

    Gottfried, Jennifer L. [U.S. Army Research Laboratory, AMSRD-ARL-WM-BD, Aberdeen Proving Ground, MD, 21005-5069 (United States)], E-mail: jennifer.gottfried@arl.army.mil; De Lucia, Frank C.; Munson, Chase A.; Miziolek, Andrzej W. [U.S. Army Research Laboratory, AMSRD-ARL-WM-BD, Aberdeen Proving Ground, MD, 21005-5069 (United States)

    2007-12-15

    We have developed a double-pulse standoff laser-induced breakdown spectroscopy (ST-LIBS) system capable of detecting a variety of hazardous materials at tens of meters. The use of a double-pulse laser improves the sensitivity and selectivity of ST-LIBS, especially for the detection of energetic materials. In addition to various metallic and plastic materials, the system has been used to detect bulk explosives RDX and Composition-B, explosive residues, biological species such as the anthrax surrogate Bacillus subtilis, and chemical warfare simulants at 20 m. We have also demonstrated the discrimination of explosive residues from various interferents on an aluminum substrate.

  7. Nd:YAG laser induced E' centers probed by in situ absorption measurements

    OpenAIRE

    Cannas, M.; Messina, F.

    2005-01-01

    We investigated various types of commercial silica irradiated with a pulsed Nd:YAG laser radiation (4.66 eV), with exposure time ranging up to 10000 s. Transient E' centers were probed in situ by measuring the amplitude of the optical absorption band at 5.8 eV (due to E' centers) both during and after irradiation. The laser-induced absorption is observed only in natural samples, whereas the synthetic materials exhibit high toughness to radiation effect. The reported results evidence that the ...

  8. Fabrication of three-dimensional plasmonic cavity by femtosecond laser-induced forward transfer.

    Science.gov (United States)

    Chen, Wei Ting; Tseng, Ming Lun; Liao, Chun Yen; Wu, Pin Chieh; Sun, Shulin; Huang, Yao-Wei; Chang, Chia Min; Lu, Chung Hao; Zhou, Lei; Huang, Ding-Wei; Liu, Ai Qun; Tsai, Din Ping

    2013-01-14

    We fabricated a three-dimensional five-layered plasmonic resonant cavity by low-cost, efficient and high-throughput femtosecond laser-induced forward transfer (fs-LIFT) technique. The fabricated cavity was characterized by optical measurements, showing two different cavity modes within the measured wavelength region which is in good agreement with numerical simulations. The mode volume corresponding to each resonance is found to be squeezed over 10(4) smaller than the cube of incident wavelength. This property may facilitate many applications in integrated optics, optical nonlinearities, and luminescence enhancement, etc.

  9. Production of 70-nm Cr dots by laser-induced forward transfer.

    Science.gov (United States)

    Sametoglu, Vahit; Sauer, Vincent T K; Tsui, Ying Y

    2013-07-29

    The effect of donor film thickness and laser beam fluence on the size of laser-induced forward transfer (LIFT) spots is studied to achieve sub-100 nm features. A 130 fs, 800 nm laser is focused on ultrathin Cr films, and the transfer and ablation thresholds of these films at various thicknesses are determined. The minimum transfer spot size decreases with decreasing donor film thickness and incident laser fluence. Minimum LIFT spots of 70-450 nm diameter are obtained from films of 20-80 nm thickness, respectively. The 70 nm diameter transfer spots obtained from sputtered continuous films are the smallest to date.

  10. Pulse Compression Based on Laser-Induced Optical Breakdown in Suspension

    Institute of Scientific and Technical Information of China (English)

    HASI Wu-Li-Ji; FU Mei-Ling; LU Huan-Huan; GONG Sheng; LU Zhi-Wei; LIN Dian-Yang; HE Wei-Ming

    2009-01-01

    Pulse compression based on laser-induced optical breakdown in suspension is investigated.The physical mechanism behind it is analyzed theoretically and validated in the Q-switched Nd:YAG laser system.A 12-ns pump pulse is suppressed to 5 ns with good fidelity in the front edge and sharp steepness in the trailing edge.The HT-270,which has a small gain coemcient and absorption coefficient,is used as a solvent,and therefore the disturbance induced by stimulated Brillouin scattering and absorption are minimized and the transmittivity is enhanced.

  11. Application of Handheld Laser-Induced Breakdown Spectroscopy (LIBS) to Geochemical Analysis.

    Science.gov (United States)

    Connors, Brendan; Somers, Andrew; Day, David

    2016-05-01

    While laser-induced breakdown spectroscopy (LIBS) has been in use for decades, only within the last two years has technology progressed to the point of enabling true handheld, self-contained instruments. Several instruments are now commercially available with a range of capabilities and features. In this paper, the SciAps Z-500 handheld LIBS instrument functionality and sub-systems are reviewed. Several assayed geochemical sample sets, including igneous rocks and soils, are investigated. Calibration data are presented for multiple elements of interest along with examples of elemental mapping in heterogeneous samples. Sample preparation and the data collection method from multiple locations and data analysis are discussed.

  12. Femtosecond diffraction dynamics of laser-induced periodic surface structures on fused silica

    Energy Technology Data Exchange (ETDEWEB)

    Hoehm, S.; Rosenfeld, A. [Max-Born-Institut fuer Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Strasse 2A, D-12489 Berlin (Germany); Krueger, J.; Bonse, J. [BAM Bundesanstalt fuer Materialforschung und - pruefung, Unter den Eichen 87, D-12205 Berlin (Germany)

    2013-02-04

    The formation of laser-induced periodic surface structures (LIPSS) on fused silica upon irradiation with linearly polarized fs-laser pulses (50 fs pulse duration, 800 nm center wavelength) is studied experimentally using a transillumination femtosecond time-resolved (0.1 ps-1 ns) pump-probe diffraction approach. This allows to reveal the generation dynamics of near-wavelength-sized LIPSS showing a transient diffraction at specific spatial frequencies even before a corresponding permanent surface relief was observed. The results confirm that the ultrafast energy deposition to the materials surface plays a key role and triggers subsequent physical mechanisms such as carrier scattering into self-trapped excitons.

  13. Ultraviolet and infrared femtosecond laser induced periodic surface structures on thin polymer films

    Energy Technology Data Exchange (ETDEWEB)

    Rebollar, Esther; Castillejo, Marta [Instituto de Quimica Fisica Rocasolano, CSIC, Serrano 119, 28006 Madrid (Spain); Vazquez de Aldana, Javier R.; Moreno, Pablo [Grupo de Investigacion en Microprocesado de Materiales con Laser, Universidad de Salamanca, Plaza de la Merced s/n, 37008 Salamanca (Spain); Perez-Hernandez, Jose A. [Centro de Laseres Pulsados Ultracortos Ultraintensos, CLPU, Plaza de la Merced s/n, 37008 Salamanca (Spain); Ezquerra, Tiberio A. [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid (Spain)

    2012-01-23

    This work demonstrates the formation of femtosecond laser induced periodic surface structures (LIPSS) by multipulse irradiation with the fundamental and 3rd harmonic of a linearly polarized Ti:sapphire laser (795 and 265 nm) on thin films of the polymers poly (ethylene terephthalate), poly (trimethylene terephthalate), and poly (carbonate bisphenol A) prepared by spin-coating. LIPSS, inspected by atomic force microscopy, are formed upon multiple pulse UV and IR irradiation with wavelength-sized period in a narrow range of fluences below the ablation threshold. Control and tunability of the size and morphology of the periodic structures become thus possible ensuring photochemical integrity of polymer films.

  14. Electron backscatter diffraction characterization of laser-induced periodic surface structures on nickel surface

    Science.gov (United States)

    Sedao, Xxx; Maurice, Claire; Garrelie, Florence; Colombier, Jean-Philippe; Reynaud, Stéphanie; Quey, Romain; Blanc, Gilles; Pigeon, Florent

    2014-05-01

    We report on the structural investigation of laser-induced periodic surface structures (LIPSS) generated in polycrystalline nickel target after multi-shot irradiation by femtosecond laser pulses. Electron backscatter diffraction (EBSD) is used to reveal lattice rotation caused by dislocation storage during LIPSS formation. Localized crystallographic damages in the LIPSS are detected from both surface and cross-sectional EBSD studies. A surface region (up to 200 nm) with 1-3° grain disorientation is observed in localized areas from the cross-section of the LIPSS. The distribution of the local disorientation is inhomogeneous across the LIPSS and the subsurface region.

  15. Pump-probe imaging of laser-induced periodic surface structures after ultrafast irradiation of Si

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, Ryan D. [Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109 (United States); Torralva, Ben [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Adams, David P. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States); Yalisove, Steven M. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2013-09-30

    Ultrafast pump-probe microscopy has been used to investigate laser-induced periodic surface structure (LIPSS) formation on polished Si surfaces. A crater forms on the surface after irradiation by a 150 fs laser pulse, and a second, subsequent pulse forms LIPSS within the crater. Sequentially delayed images show that LIPSS with a periodicity slightly less than the fundamental laser wavelength of 780 nm appear on Si surfaces ∼50 ps after arrival of the second pump laser pulse, well after the onset of melting. LIPSS are observed on the same timescale as material removal, suggesting that their formation involves material ejection.

  16. Laser Induced Periodic Surface Structures induced by surface plasmons coupled via roughness

    Science.gov (United States)

    Gurevich, E. L.; Gurevich, S. V.

    2014-05-01

    In this paper the formation mechanisms of the femtosecond laser-induced periodic surface structures (LIPSS) are discussed. One of the most frequently used theories explains the structures by interference between the incident laser beam and surface plasmon-polariton waves. The latter is most commonly attributed to the coupling of the incident laser light to the surface roughness. We demonstrate that this excitation of surface plasmons contradicts the results of laser-ablation experiments. As an alternative approach to the excitation of LIPSS we analyse development of hydrodynamic instabilities in the melt layer.

  17. Pump-probe imaging of laser-induced periodic surface structures after ultrafast irradiation of Si

    Science.gov (United States)

    Murphy, Ryan D.; Torralva, Ben; Adams, David P.; Yalisove, Steven M.

    2013-09-01

    Ultrafast pump-probe microscopy has been used to investigate laser-induced periodic surface structure (LIPSS) formation on polished Si surfaces. A crater forms on the surface after irradiation by a 150 fs laser pulse, and a second, subsequent pulse forms LIPSS within the crater. Sequentially delayed images show that LIPSS with a periodicity slightly less than the fundamental laser wavelength of 780 nm appear on Si surfaces ˜50 ps after arrival of the second pump laser pulse, well after the onset of melting. LIPSS are observed on the same timescale as material removal, suggesting that their formation involves material ejection.

  18. Subnanosecond-laser-induced periodic surface structures on prescratched silicon substrate

    Science.gov (United States)

    Hongo, Motoharu; Matsuo, Shigeki

    2016-06-01

    Laser-induced periodic surface structures (LIPSS) were fabricated on a prescratched silicon surface by irradiation with subnanosecond laser pulses. Low-spatial-frequency LIPSS (LSFL) were observed in the central and peripheral regions; both had a period Λ close to the laser wavelength λ, and the wavevector orientation was parallel to the electric field of the laser beam. The LSFL in the peripheral region seemed to be growing, that is, expanding in length with increasing number of pulses, into the outer regions. In addition, high-spatial-frequency LIPSS, Λ ≲ λ /2, were found along the scratches, and their wavevector orientation was parallel to the scratches.

  19. Laser-induced fusion of human embryonic stem cells with optical tweezers

    Science.gov (United States)

    Chen, Shuxun; Cheng, Jinping; Kong, Chi-Wing; Wang, Xiaolin; Han Cheng, Shuk; Li, Ronald A.; Sun, Dong

    2013-07-01

    We report a study on the laser-induced fusion of human embryonic stem cells (hESCs) at the single-cell level. Cells were manipulated by optical tweezers and fused under irradiation with pulsed UV laser at 355 nm. Successful fusion was indicated by green fluorescence protein transfer. The influence of laser pulse energy on the fusion efficiency was investigated. The fused products were viable as gauged by live cell staining. Successful fusion of hESCs with somatic cells was also demonstrated. The reported fusion outcome may facilitate studies of cell differentiation, maturation, and reprogramming.

  20. Application of laser-induced photoacoustic spectroscopy for determination of plutonium concentration in nuclear waste solutions.

    Science.gov (United States)

    Surugaya, Naoki; Sato, Soichi; Jitsukata, Syu; Watahiki, Masaru

    2008-04-01

    Laser-induced photoacoustic spectroscopy was used in a quantitative analysis of Pu in HNO3 medium. Plutonium was quantitatively oxidized to Pu(VI) using Ce(IV). The photoacoustic measurement of Pu(VI) with maximum absorption at 830.5 nm was subsequently performed to determine the concentration. The photoacoustic signal was linearly proportional to the Pu(VI) ion concentration. The detection limit of Pu(VI) was estimated to be 0.5 microg mL(-1) (3sigma) in 3 M HNO3. By the proposed method, Pu concentration was successfully determined in a nuclear waste solution for use in nuclear materials management.

  1. Aligned carbon nanotubes catalytically grown on iron-based nanoparticles obtained by laser-induced CVD

    OpenAIRE

    Le Normand, Francois; Cojocaru, Costel Sorin; Ersen, Ovidiu; Legagneux, Pierre; Gangloff, Laurent; Fleaca, C.; Alexandrescu, Rodica; Dumitrache, Florin; Morjan, Ion

    2007-01-01

    International audience; Iron-based nanoparticles are prepared by a laser-induced chemical vapor deposition (CVD) process. They are characterized as body-centered Fe and Fe2O3 (maghemite/magnetite) particles with sizes ::;5 and 10 nm, respectively. The Fe particles are embedded in a protective carbon matrix. Both kind of particles are dispersed by spin-coating on SiO2/Si(1 0 0) flat substrates. They are used as catalyst to grow carbon nanotubes by a plasma- and filaments-assisted catalytic CVD...

  2. Acetone, a laser-induced fluorescence study with rotational resolution at 320 nm

    Science.gov (United States)

    Zuckermann, Hanna; Haas, Yehuda; Drabbels, Marcel; Heinze, Johannes; Meerts, W. Leo; Reuss, Joerg; van Bladel, John

    1992-06-01

    The forbidden S 1←S 0 transition of acetone has been investigated by laser-induced fluorescence measurements with a resolution of 270 MHz. The rotational structure demonstrates, that (i) one deals with a-type transitions and (ii) there is a strong coupling between the torsional motion of the two CH 3 groups and the tunneling, out-of-plane wagging motion ( v23) of acetone. The interpretation of torsion-vibrational combination bands is less conclusive and thus the discussion still has a preliminary character.

  3. Laser-induced breakdown spectroscopy at high temperatures in industrial boilers and furnaces.

    Science.gov (United States)

    Blevins, Linda G; Shaddix, Christopher R; Sickafoose, Shane M; Walsh, Peter M

    2003-10-20

    Laser-induced breakdown spectroscopy (LIBS) was applied (1) near the superheater of an electric power generation boiler burning biomass, coal, or both; (2) at the exit of a glass-melting furnace burning natural gas and oxygen; and (3) near the nose arches of two paper mill recovery boilers burning black liquor. Difficulties associated with the high temperatures and high particle loadings in these environments were surmounted by use of novel LIBS probes. Echelle and linear spectrometers coupled to intensified CCD cameras were used individually and sometimes simultaneously. Elements detected include Na, K, Ca, Mg, C, B, Si, Mn, Al, Fe, Rb, Cl, and Ti.

  4. Laser-induced charge transfer in the HeH/sup 2 +/ quasimolecule

    Energy Technology Data Exchange (ETDEWEB)

    Errea, L.F.; Mendez, L.; Riera, A.

    1983-11-01

    In a recent publication, the charge transfer cross section for He/sup 2 +/+H(ls) collisions through photon-assisted 2psigma--3dsigma transitions was calculated; this calculation, however, contained several errors whose quantitative--even qualitative effect on the results is not obvious. We present a correct evaluation of this laser-induced cross section, which turns out to be larger, and present a maximum for longer wavelengths, than the values previously reported. In addition, we have checked the applicability of perturbation theory, of the stationary phase, uniform and Landau--Zener approximations, and the importance of potentially competitive photon-assisted reactions.

  5. Laser Induced Periodic Surface Structures induced by surface plasmons coupled via roughness

    Energy Technology Data Exchange (ETDEWEB)

    Gurevich, E.L., E-mail: gurevich@lat.rub.de [Chair of Applied Laser Technology, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum (Germany); Gurevich, S.V., E-mail: gurevics@uni-muenster.de [Institute for Theoretical Physics, University of Münster, Wilhelm-Klemm-Straße 9, 48149 Münster (Germany)

    2014-05-01

    In this paper the formation mechanisms of the femtosecond laser-induced periodic surface structures (LIPSS) are discussed. One of the most frequently used theories explains the structures by interference between the incident laser beam and surface plasmon-polariton waves. The latter is most commonly attributed to the coupling of the incident laser light to the surface roughness. We demonstrate that this excitation of surface plasmons contradicts the results of laser-ablation experiments. As an alternative approach to the excitation of LIPSS we analyse development of hydrodynamic instabilities in the melt layer.

  6. Photomultiplier nonlinear response in time-domain laser-induced luminescence spectroscopy

    Directory of Open Access Journals (Sweden)

    Leandro José Bossy Schip

    2007-02-01

    Full Text Available A new procedure to find the limiting range of the photomultiplier linear response of a low-cost, digital oscilloscope-based time-resolved laser-induced luminescence spectrometer (TRLS, is presented. A systematic investigation on the instrument response function with different signal input terminations, and the relationship between the luminescence intensity reaching the photomultiplier and the measured decay time are described. These investigations establish that setting the maximum intensity of the luminescence signal below 0.3V guarantees, for signal input terminations equal or higher than 99.7 ohm, a linear photomultiplier response.

  7. Toward 3D Printing of Pure Metals by Laser-Induced Forward Transfer.

    Science.gov (United States)

    Visser, Claas Willem; Pohl, Ralph; Sun, Chao; Römer, Gert-Willem; Huis in 't Veld, Bert; Lohse, Detlef

    2015-07-15

    3D printing of common metals is highly challenging because metals are generally solid at room conditions. Copper and gold pillars are manufactured with a resolution below 5 μm and a height up to 2 mm, using laser-induced forward transfer to create and eject liquid metal droplets. The solidified drop's shape is crucial for 3D printing and is discussed as a function of the laser energy. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Time-resolved laser-induced incandescence from multiwalled carbon nanotubes in air

    Energy Technology Data Exchange (ETDEWEB)

    Mitrani, J. M. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA; Shneider, M. N. [Department of Mechanical Engineering, Princeton University, Princeton, New Jersey 08544, USA

    2015-01-26

    We observed temporal laser-induced incandescence (LII) signals from multiwalled carbon nanotubes(MWCNTs) suspended in ambient air. Unlike previous LII experiments with soot particles, which showed that primary particles with larger diameters cool at slower timescales relative to smaller particles, we observed that thicker MWCNTs with larger outer diameters (ODs) cool at faster timescales relative to thinner MWCNTs with smaller ODs. We suggested a simple explanation of this effect, based on the solution of one-dimensional nonstationary heat conduction equation for the initial non-uniform heating of MWCNTs with ODs greater than the skin depth.

  9. Laser-induced narrowband coherent synchrotron radiation: Efficiency versus frequency and laser power

    Directory of Open Access Journals (Sweden)

    C. Evain

    2010-09-01

    Full Text Available We analyze the narrowband terahertz emission process occurring from electron bunches passing in a bending magnet, after a laser-induced sinusoidal modulation has been performed. In particular, we focus on experimental tunability curves, and power scalings with current and laser power. Theoretically, we simplify the problem formulation using the slowly varying envelope approximation. At low powers, the scaling with laser power appears to be quadratic, and analytical expressions for the tuning curves are obtained. Emission at first passage in the bending magnet, and after one full turn in the storage ring, are considered both experimentally and theoretically. The experiments are performed on the UVSOR-II storage ring.

  10. A parametric study of laser induced ablation-oxidation on porous silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    De Stefano, Luca; Rea, Ilaria; Nigro, M Arcangela; Della Corte, Francesco G; Rendina, Ivo [National Council of Research-Institute for Microelectronic and Microsystems-Department of Naples, Via P Castellino 111, 80131 Naples (Italy)], E-mail: luca.destefano@na.imm.cnr.it

    2008-07-02

    We have investigated the laser induced ablation-oxidation process on porous silicon layers having different porosities and thicknesses by non-destructive optical techniques. In particular, the interaction between a low power blue light laser and the porous silicon surfaces has been characterized by variable angle spectroscopic ellipsometry and Fourier transform infrared spectroscopy. The oxidation profiles etched on the porous samples can be tuned as functions of the layer porosity and laser fluence. Oxide stripes of width less than 2 {mu}m and with thicknesses between 100 nm and 5 {mu}m have been produced, depending on the porosity of the porous silicon, by using a 40 x focusing objective.

  11. Low-Cost Fabrication of Printed Electronics Devices through Continuous Wave Laser-Induced Forward Transfer.

    Science.gov (United States)

    Sopeña, Pol; Arrese, Javier; González-Torres, Sergio; Fernández-Pradas, Juan Marcos; Cirera, Albert; Serra, Pere

    2017-09-06

    Laser-induced forward transfer (LIFT) is a direct-writing technique that allows printing inks from a liquid film in a similar way to inkjet printing but with fewer limitations concerning ink viscosity and loading particle size. In this work, we prove that liquid inks can be printed through LIFT by using continuous wave (CW) instead of pulsed lasers, which allows a substantial reduction in the cost of the printing system. Through the fabrication of a functional circuit on both rigid and flexible substrates (plastic and paper), we provide a proof-of-concept that demonstrates the versatility of the technique for printed electronics applications.

  12. Electrially tunable photonic bandgap guidance in a liquid crystal filled photonic crystal fiber

    DEFF Research Database (Denmark)

    Haakestad, Magnus W.; Alkeskjold, Thomas Tanggaard; Nielsen, Martin Dybendal;

    2005-01-01

    Tunable bandgap guidance is obtained by filling the holes of a solid core photonic crystal fiber with a nematic liquid crystal and applying an electric field. The response times are measured and found to be in the millisecond range.......Tunable bandgap guidance is obtained by filling the holes of a solid core photonic crystal fiber with a nematic liquid crystal and applying an electric field. The response times are measured and found to be in the millisecond range....

  13. The improvement of laser induced damage resistance of optical workpiece surface by hydrodynamic effect polishing

    Science.gov (United States)

    Peng, Wenqiang; Guan, Chaoliang; Li, Shengyi; Wang, Zhuo

    2016-10-01

    Surface and subsurface damage in optical element will greatly decrease the laser induced damage threshold (LIDT) in the intense laser optical system. Processing damage on the workpiece surface can be inevitably caused when the material is removed in brittle or plastic mode. As a non-contact polishing technology, hydrodynamic effect polishing (HEP) shows very good performance on generating an ultra-smooth surface without damage. The material is removed by chemisorption between nanoparticle and workpiece surface in the elastic mode in HEP. The subsurface damage and surface scratches can be effectively removed after the polishing process. Meanwhile ultra-smooth surface with atomic level surface roughness can be achieved. To investigate the improvement of LIDT of optical workpiece, polishing experiment was conducted on a magnetorheological finishing (MRF) silica glass sample. AFM measurement results show that all the MRF directional plastic marks have been removed clearly and the root-mean-square (rms) surface roughness has decreased from 0.673nm to 0.177nm after HEP process. Laser induced damage experiment was conducted with laser pulse of 1064nm wavelength and 10ns time width. Compared with the original state, the LEDT of the silica glass sample polished by HEP has increased from 29.78J/cm2 to 45.47J/cm2. It demonstrates that LIDT of optical element treated by HEP can be greatly improved for ultra low surface roughness and nearly defect-free surface/subsurface.

  14. [Determination of minor elements in stainless steel by laser-induced plasma spectroscopy (LIPS)].

    Science.gov (United States)

    Li, Jing; Zhai, Chao; Zhang, Shi-Ding; Zhang, Jian-Qiu; Meng, Xiang-Ru

    2008-04-01

    Laser-induced plasma spectroscopy (LIPS) is characterized by its non-contact and real-time analysis. Its application to the determination of steel composition can meet the need of high-speed, continuous and automatic production in large steel companies. In the present article the minor elements concentrations of aluminum, manganese, cobalt, molybdenum, and titanium in a series of stainless steel 1Cr18Ni9Ti samples were determinate by laser-induced plasma spectroscopy, based on a Nd : YAG Q-switched solid laser with wavelength 1 064 nm as an exciting source and ICCD as detector. In the experiment the working delay time and gate time of ICCD were set suitably to get high signal-to-noise ratio emission spectral lines, and the internal standardization method related to matrix effect was used to deal with spectral data. Experiment results show that the concentration ratios of all the measured elements versus the reference element ferrum have a good linear relationship with the intensity ratios of them, the detection limits of the five tested elements are within 150 microg x g(-1).

  15. Femtosecond laser-induced microstructures in glasses and applications in micro-optics.

    Science.gov (United States)

    Qiu, Jianrong

    2004-01-01

    Femtosecond laser has been widely used in microscopic modifications to materials due to its ultra-short laser pulse and ultrahigh light intensity. When a transparent material e.g. glass is irradiated by a tightly focused femtosecond laser, the photo-induced reaction is expected to occur only near the focused part of the laser beam inside the glass due to the multiphoton processes. We observed various induced structures e.g. color center defects, refractive index change, micro-void and micro-crack, in glasses after the femtosecond laser irradiation. In this paper, we review the femtosecond laser induced phenomena and discuss the mechanisms of the observed phenomena. We also introduce the fabrication of various micro-optical components, e.g. optical waveguide, micro-grating, micro-lens, fiber attenuator, 3-dimensional optical memory by using the femtosecond laser-induced structures. The femtosecond laser will open new possibilities in the fabrication of micro-optical components with various optical functions.

  16. Hybrid optoacoustic and ultrasound biomicroscopy monitors’ laser-induced tissue modifications and magnetite nanoparticle impregnation

    Science.gov (United States)

    Estrada, Héctor; Sobol, Emil; Baum, Olga; Razansky, Daniel

    2014-12-01

    Tissue modification under laser radiation is emerging as one of the advanced applications of lasers in medicine, with treatments ranging from reshaping and regeneration of cartilage to normalization of the intraocular pressure. Laser-induced structural alterations can be studied using conventional microscopic techniques applied to thin specimen. Yet, development of non-invasive imaging methods for deep tissue monitoring of structural alterations under laser radiation is of great importance, especially for attaining efficient feedback during the procedures. We developed a fast scanning biomicroscopy system that can simultaneously deliver both optoacoustic and pulse-echo ultrasound contrast from intact tissues and show that both modalities allow manifesting the laser-induced changes in cartilage and sclera. Furthermore, images of the sclera samples reveal a crater developing around the center of the laser-irradiated spot as well as a certain degree of thickening within the treated zone, presumably due to pore formation. Finally, we were able to observe selective impregnation of magnetite nanoparticles into the cartilage, thus demonstrating a possible contrast enhancement approach for studying specific treatment effects. Overall, the new imaging approach holds promise for development of noninvasive feedback control systems that could guarantee efficacy and safety of laser-based medical procedures.

  17. Laser-induced breakdown spectroscopy measurements of uranium and thorium powders and uranium ore

    Energy Technology Data Exchange (ETDEWEB)

    Judge, Elizabeth J. [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Barefield, James E., E-mail: jbarefield@lanl.gov [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Berg, John M. [Manufacturing Engineering and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Clegg, Samuel M.; Havrilla, George J.; Montoya, Velma M.; Le, Loan A.; Lopez, Leon N. [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2013-05-01

    Laser-induced breakdown spectroscopy (LIBS) was used to analyze depleted uranium and thorium oxide powders and uranium ore as a potential rapid in situ analysis technique in nuclear production facilities, environmental sampling, and in-field forensic applications. Material such as pressed pellets and metals, has been extensively studied using LIBS due to the high density of the material and more stable laser-induced plasma formation. Powders, on the other hand, are difficult to analyze using LIBS since ejection and removal of the powder occur in the laser interaction region. The capability of analyzing powders is important in allowing for rapid analysis of suspicious materials, environmental samples, or trace contamination on surfaces since it most closely represents field samples (soil, small particles, debris etc.). The rapid, in situ analysis of samples, including nuclear materials, also reduces costs in sample collection, transportation, sample preparation, and analysis time. Here we demonstrate the detection of actinides in oxide powders and within a uranium ore sample as both pressed pellets and powders on carbon adhesive discs for spectral comparison. The acquired LIBS spectra for both forms of the samples differ in overall intensity but yield a similar distribution of atomic emission spectral lines. - Highlights: • LIBS analysis of mixed actinide samples: depleted uranium oxide and thorium oxide • LIBS analysis of actinide samples in powder form on carbon adhesive discs • Detection of uranium in a complex matrix (uranium ore) as a precursor to analyzing uranium in environmental samples.

  18. Improving Resolution of Confocal Laser Induced Fluorescence in Argon Helicon Plasma

    Science.gov (United States)

    Soderholm, Mark; Vandervort, Robert; Scime, Earl; McKee, John; McCarren, Dustin

    2014-10-01

    Laser Induced Fluorescence (LIF) provides measurements of flow speed, temperature and when absolutely calibrated, density of ions or neutrals in a plasma. Traditionally, laser induced fluorescence requires two ports on a plasma device. One port is used for laser injection and the other is used for fluorescence emission collection. Traditional LIF is tedious and time consuming to align. These difficulties motivate the development of an optical configuration that requires a single port and remains fully aligned at all times; confocal LIF. Our confocal optical design employs a single two inch diameter lens to both inject the laser light and collect the stimulated emission from an argon plasma. A dichroic mirror is used to separate the injected laser light from the collected emission. The measurement location is scanned radially by manually adjusting the final focusing lens position. In the initial version of the confocal optical system, measurements were poorly resolved radially because they were integrated over a fairly large path length (~4 cm) centered at the focal point. Here we present collected data from a modified configuration that significantly improves the special resolution of confocal measurements. The confocal measurements are compared to traditional, two-port, LIF measurements over the same radial range.

  19. Eye-safe infrared laser-induced breakdown spectroscopy (LIBS) emissions from energetic materials

    Science.gov (United States)

    Brown, Ei E.; Hömmerich, Uwe; Yang, Clayton C.; Jin, Feng; Trivedi, Sudhir B.; Samuels, Alan C.

    2016-05-01

    Laser-induced breakdown spectroscopy is a powerful diagnostic tool for detection of trace elements by monitoring the atomic and ionic emission from laser-induced plasmas. Besides elemental emissions from conventional UV-Vis LIBS, molecular LIBS emission signatures of the target compounds were observed in the long-wave infrared (LWIR) region in recent studies. Most current LIBS studies employ the fundamental Nd:YAG laser output at 1.064 μm, which has extremely low eye-damage threshold. In this work, comparative LWIR-LIBS emissions studies using traditional 1.064 μm pumping and eye-safe laser wavelength at 1.574 μm were performed on several energetic materials for applications in chemical, biological, and explosive (CBE) sensing. A Q-switched Nd: YAG laser operating at 1.064 μm and the 1.574 μm output of a pulsed Nd:YAG pumped Optical Parametric Oscillator were employed as the excitation sources. The investigated energetic materials were studied for the appearance of LWIR-LIBS emissions (4-12 μm) that are directly indicative of oxygenated breakdown products as well as partially dissociated and recombination molecular species. The observed molecular IR LIBS emission bands showed strong correlation with FTIR absorption spectra of the studied materials for 1.064 μm and 1.574 μm pump wavelengths.

  20. Identification and removal of laser-induced noise in photoacoustic imaging using singular value decomposition.

    Science.gov (United States)

    Hill, Emma R; Xia, Wenfeng; Clarkson, Matthew J; Desjardins, Adrien E

    2017-01-01

    Singular value decomposition (SVD) was used to identify and remove laser-induced noise in photoacoustic images acquired with a clinical ultrasound scanner. This noise, which was prominent in the radiofrequency data acquired in parallel from multiple transducer elements, was induced by the excitation light source. It was modelled by truncating the SVD matrices so that only the first few largest singular value components were retained, and subtracted prior to image reconstruction. The dependency of the signal amplitude and the number of the largest singular value components used for noise modeling was investigated for different photoacoustic source geometries. Validation was performed with simulated data and measured noise, and with photoacoustic images acquired from the human forearm and finger in vivo using L14-5/38 and L40-8/12 linear array clinical imaging probes. The use of only one singular value component was found to be sufficient to achieve near-complete removal of laser-induced noise from reconstructed images. This method has strong potential to increase image quality for a wide range of photoacoustic imaging systems with parallel data acquisition.