• JLA Vol:16 Iss:2 (Investigation of weld cracking in Nd:yttrium–aluminum–garnet keyhole spot welding of materials used in optoelectronic packaging)

    Geoff J. Shannon
    Unitek Miyachi Corporation, 1820 S. Myrtle Avenue, Monrovia, California 91017

    Bernard Q. Li
    Honeywell VCSEL Optical Division, Minnesota

    The welding of a problematic optical device weld joint between dissimilar materials is investigated in depth. The original material combination of cold rolled steel 1010 with 6 μm of gold coating and 304 L produced consistent weld cracking. The CRS1010 material was fixed, however the other component was open to material selection. The materials tested were 304 L stainless steel, kovar, invar, and Carpenter high permeability 49 alloy. The effect of these different materials, laser pulse parameters, lev...


  • JLA Vol:16 Iss:2 (Laser direct writing and doping of diamond-like carbon, polycrystalline diamond, and single crystal silicon carbide)

    I. A. Salama
    Laser-Aided Manufacturing, Materials and Micro-Processing Laboratory (LAMMMP), School of Optics, Center for Research and Education in Optics and Lasers (CREOL), Mechanical, Materials and Aerospace Engineering Department, University of Central Florida, Orlando, Florida 32816-2700

    N. R. Quick
    Applicote Associates, 894 Silverado Court, Lake Mary, Florida 32746

    A. Kar
    Laser-Aided Manufacturing, Materials and Micro-Processing Laboratory (LAMMMP), School of Optics, Center for Research and Education in Optics and Lasers (CREOL), Mechanical, Materials and Aerospace Engineering Department, University of Central Florida, Orlando, Florida 32816-270...


  • JLA Vol:16 Iss:2 (Laser short pulse heating of copper: Thermo–elasto–plastic analysis)

    A. F. M. Arif
    B. S. Yilbas
    ME Department, KFUPM. Dhahran, Saudi Arabia

    Laser short pulse heating of metallic substrates results in excessive electron temperatures in the surface vicinity. This gives rise to nonequilibrium energy transport in the region irradiated by a laser beam. Moreover, the thermomechanical coupling effect should be incorporated into the energy transport equation as lattice site temperature increases. In the present study, laser short pulse heating of copper is considered. The electron kinetic theory approach is employed to model the nonequilibrium heating process while thermomechanical coupling is introduced in the energy transport equation t...


  • JLA Vol:16 Iss:2 (Quality and costs analysis of laser welded all steel sandwich panels)

    Henrikki Pantsar
    Antti Salminen
    Lappeenranta University of Technology, FIN 53850 Lappeenranta, Finland

    Anssi Jansson
    VTT Industrial Systems, FIN 53850 Lappeenranta, Finland

    Veli Kujanpa¨a¨
    Lappeenranta University of Technology, FIN 53850 Lappeenranta, Finland

    Laser welding is a fast and flexible way to manufacture all steel sandwich panels. Economically the most feasible solution is often to weld as large panels as possible. In corrugated core all steel sandwich panel applications the effect of an air gap in welding is difficult to eliminate when welding large panels. A system for welding large panels with a las...


  • JLA Vol:16 Iss:2 (The influence of the pulse length on the drilling of metals with an excimer laser)

    Aart Schoonderbeek

    Cornelis A. Biesheuvel
    Ramon M. Hofstra
    Nederlands Centrum voor Laser Research (NCLR) B.V., P.O. Box 2662, Enschede, The Netherlands

    Klaus-J. Boller
    Johan Meijer

    Laser parameters, which significantly influence laser-material interaction processes, are the wavelength, the energy, and the power density. Additionally, there are parameters, like the pulse length, which also strongly influence processing speed and quality. Studies where different types of lasers have been used indicate that long pulses are beneficial for processing speed. However, when different types of laser syst...


  • JLA Vol:16 Iss:3 (A procedure for the estimation of intrabeam hazard distances and optical density requirements under the ANSI Z136.1-2000 Standard)

    Robert J. Thomas
    Benjamin A. Rockwell
    Air Force Research Laboratory, Brooks AFB, Texas 78235-5215

    Wesley J. Marshall
    USACHPPM, Aberdeen Proving Ground, Maryland 21010-5422

    Robert C. Aldrich
    Mary F. Gorschboth
    Sheldon A. Zimmerman
    Dahlgren Division, Naval Surface Warfare Center, Dahlgren, Virginia 22448-5100

    R. James Rockwell
    Rockwell Laser Industries, Cincinnati, Ohio 45243

    Over the past few years, a comprehensive rewrite of the American National Standard for Safe Use of Lasers (ANSI Z136.1) has been conducted [American National Standards Institute, Z136.1-2000 America...


  • JLA Vol:16 Iss:3 (Cementum melting after dye-assisted holmium laser irradiation)

    L. Bachmann
    W. Rossi
    D. M. Zezell
    Centro de Lasers e Aplicac¸o˜es (CLA), Instituto de Pesquisas Energe´ticas e Nucleares (IPEN), Av. Lineu Prestes, 2242 Cidade Universita´ria 05508-900 Sa˜o Paulo-SP, Brazil

    Dye-assisted laser irradiation with black ink or vegetable coal has been used in procedures involving hard tissue irradiation using neodymium or diode lasers. The objective of this work is to evaluate the human root surface melting, after dye-assisted holmium irradiation with subablative fluences. Human cervical root regions were selected, irradiated with a holmium laser with emission at 2.065 μm, pulse width of 40...


  • JLA Vol:16 Iss:3 (Diode laser beam absorption in laser transformation hardening of low alloy steel)

    Henrikki Pantsar
    Veli Kujanpa¨a¨
    Laser Processing Laboratory, Lappeenranta University of Technology, FIN 53851 Lappeenranta, Finland

    Defining and controlling the absorption of the laser beam is important since all of the heating energy is brought to the material through absorption. Even small variations in the absorption change the laser power needed by hundreds of W. In this study the absorption of a diode laser beam to low alloy steel has been measured by a liquid calorimeter and the surface temperature has been measured with a dual wavelength pyrometer. The varied processing parameters were the power intensity of the beam, the interaction time, and the...


  • JLA Vol:16 Iss:3 (Eye hazard characterization of an optical klystron free electron laser beam)

    Ben E. Edwards
    Radiation Safety Division, Duke University Medical Center, Durham, North Carolina 27710

    Igor V. Pinayev
    Patrick W. Wallace
    Free Electron Laser Laboratory, Duke University, Durham, North Carolina 27710

    A free electron laser (FEL) uses an accelerated electron beam to generate laser light. By adjusting the electron beam energy and other parameters, FELs can generate tunable, coherent light over a range from ultraviolet to millimeter wavelengths. Many FELs are building-sized systems that remain at the site of construction, and are not produced for sale or commercial distribution. Federal laser regulatory requirements for hazard ch...


  • JLA Vol:16 Iss:3 (Laser microspot welding of copper)

    S. Amorosi
    Th. Sidler
    R. P. Salathe´
    Advanced Photonics Laboratory, Ecole Polytechnique Fe´de´rale de Lausanne, Switzerland

    H. P. Schwob
    J. Hertzberg
    LASAG AG, Thun, Switzerland

    We describe a novel procedure for highly reliable microspot welding of copper based on a calibrated on-line reflectivity measurement. This parameter is used to control the laser power slope and the weld spot diameter. Reliable welds are obtained without the need of other active control mechanisms. The new technique allows realizing welds with a diameter close to the laser beam waist and leads to a reduction in the relative ...



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