• JLA Vol:22 Iss:1 (Surface effects of alumina ceramics machined with femtosecond lasers)


    Authors:
    J. Meeker
    A. E. Segall
    V. V. Semak
    Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802


    Laser machining is now an accepted method for shaping and modifying ceramics and is rapidly replacing other methods such as grinding and etching. In fact, new innovations such as short pulsed or femtosecond lasers have drastically decreased the amount of unwanted damage associated with laser machining. However, laser machining does still alter the surface and can change the flaw populations and the strength. In order to investigate this effect, the flaw populations and strengths of both unaltered and femtosecond...

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  • JLA Vol:24 Iss:2 (Synthesis of nitrogen-doped diamond films using vibrational excitation of ammonia molecules in laser-assisted combustion flames)


    Authors:
    L. S. Fan
    Z. Q. Xie
    J. B. Park
    X. N. He
    Y. S. Zhou
    Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0511

    L. Jiang
    Department of Mechanical and Automation Engineering, Beijing Institute of Technology, Beijing 100081, People’s Republic of China

    Y. F. Lu
    Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0511


    Nitrogen-doped diamond was synthesized in open air using laser-assisted combustion flame method. A wavelength-tunable CO2 laser was used to resonantly excite the vibration mod...

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  • JLA Vol:6 Iss:3 (Acoustic emission response of soda lime glass after a single Nd‐YAG laser pulse)


    Authors:
    R. Harrysson
    P. Vomacka
    Department of Engineering Materials, Luleå University of Technology, S‐951 87 Luleå, Sweden


    When machining brittle solids with a laser, crack formation can occur in the material around the irradiated area causing a strength reduction of the machined material. The purpose of this work was to study a well known brittle material (soda lime glass) by means of acoustic emission (AE) in order to investigate the correlation between visually observed crack formation and detected AE energy released by the crack formation in the material. During and after irradiation of soda lime glass with an Nd‐YAG laser pulse, the number...

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  • JLA Vol:1 Iss:2 (A Study in Surface Alloying of Titanium Alloys)


    Authors:
    A. Bharti
    R. Sivakumar
    Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad‐500 258, India

    D. B. Goel
    Department of Metallurgical Engineering, University of Roorkee, Roorkee‐247 667, India


    A 5 KW CW CO2 laser has been used to alloy the surface of Ti6Al4V alloy with carbon. As a result the average microhardness was increased from 365 to 600 kg/mm.2 Compositional inhomogeneity was observed on the alloyed surface, however the compositional inhomogeneity index reduced considerably by cross scanning with defocused laser beam. Surface roughness of the alloyed surface was also studied and the roughn...

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  • JLA Vol:15 Iss:4 (Solution of two-temperature thermal diffusion model of laser–metal interactions)


    Authors:
    S. R. Vatsya
    Kuljit S. Virk
    Integrated Manufacturing Technologies Institute, National Research Council of Canada, 800 Collip Circle, London, Ontario N6G 4X8, Canada


    The two temperature coupled equations, modeling thermal diffusion during laser-induced ablation of metals, are solved under the assumptions that the electron and the lattice heat capacities, and the thermal conductivity remain constant in the process. In view of its practical value, the solution is initially obtained for the energy sources with a Gaussian distribution. The solution is then generalized to include a larger class of source terms for comparison with other results. Present analysis is vali...

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  • JLA Vol:20 Iss:1 (Experimental investigation of remote welding with CO<sub>2</sub> and Nd:YAG laser-based systems)


    Authors:
    George Tsoukantas
    Aristidis Stournaras
    George Chryssolouris
    Laboratory for Manufacturing Systems and Automation, Department of Mechanical Engineering and Aeronautics, University of Patras, Patras 265 00, Greece


    Remote welding provides new possibilities for highly productive and flexible joining of metal structures, especially in the automotive industry. This study presents an experimental investigation on the behavior of the lap welds’ geometrical characteristics with respect to the laser beam inclination. Two remote welding systems (RWSs) have been utilized: a large field RWS with a CO2 laser and a small field RWS with an Nd:YAG las...

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  • JLA Vol:8 Iss:5 (Diode&hyphen;pumped Nd:YAG laser for precision laser machining)


    Authors:
    Jason Machan
    Marcy Valley
    Gerry Holleman
    Marc Mitchell
    Dave Burchman
    Jim Zamel
    George Harpole
    Hagop Injeyan
    Len Marabella
    TRW R1/1184, One Space Park, Redondo Beach, CA 90278, U.S.A.


    Results are presented on a high power, diode&hyphen;pumped, pulsed Nd:YAG laser for precision laser machining. The laser is an unstable resonator with a graded reflectivity outcoupler, generating a beam with excellent beam quality. The gain medium is a single zig&hyphen;zag slab, pumped symmetrically by diode arrays. The use of diode arrays minimizes the thermal loading on the slab, and the zig...

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  • JLA Vol:2 Iss:1 (The Energy Transfer Efficiency in Laser Welding Process)


    Authors:
    T. H. Kim
    Charles E. Albright
    Schichan Chiang
    Department of Welding Engineering, The Ohio State University, 190 W. 19th Ave., Columbus, Ohio 43210


    The process efficiency of laser beam welding was measured as a function of travel speed. Temperature measurements were carried out during the bead&hyphen;on&hyphen;plate laser welding of mild steel with a focused 2KW CO2 laser beam at various welding travel speeds. The laser welding process efficiency (power delivered to work/power in the beam) was calculated from the ratio of the heat content of the welded the specimen to the available laser beam energy (power × time). In the deep penetr...

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  • JLA Vol:14 Iss:2 (Development of simulated pigmented lesions in an optical skin-tissue phantom: Experimental measurements in the visible and near infrared)


    Authors:
    Manuela Lualdi
    Ambrogio Colombo
    Alberto Mari
    Stefano Tomatis
    Renato Marchesini
    Medical Physics Unit, Istituto Nazionale per lo Studio e la Cura dei Tumori, Milan, Italy


    Realistic, pigmented skin simulants (“phantoms”) can be useful in optimizing dermal laser procedures and for laser surgical training. Diffuse reflectance of skin pigmented lesions depends on the amount and distribution of the absorbing/diffusing chromophores, mainly hemoglobin and melanin, embedded in the skin layers. The reason why diffuse reflectance of benign melanocytic lesions is different from that of melanoma is still unclear. In an attempt...

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  • JLA Vol:18 Iss:3 (The influence of joint gap on the strength of hybrid Nd:yttrium-aluminum-garnet laser-metal inert gas welds)


    Authors:
    M. Wouters
    Division of Manufacturing Systems Engineering, Luleå University of Technology, S-971 87 Luleå, Sweden

    J. Powell
    Division of Manufacturing Systems Engineering, Luleå University of Technology, S-971 87 Luleå, Sweden and Laser Expertise Ltd., Acorn Park Ind. Estate, Harrimans Lane, Nottingham NG7 2TR, United Kingdom

    A. F. H. Kaplan
    Division of Manufacturing Systems Engineering, Luleå University of Technology, S-971 87 Luleå, Sweden


    This article presents the results of an experimental and theoretical analysis of the effect of joint gap on the strength of hybrid laser-metal inert gas welds. ...

    $25.00

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