• JLA Vol:8 Iss:5 (Laser drilling of advanced materials: Effects of peak power, pulse format, and wavelength)

    X. Chen
    W. T. Lotshaw
    A. L. Ortiz
    P. R. Staver
    C. E. Erikson
    M. H. McLaughlin
    T. J. Rockstroh

    The quality of laser‐drilled holes is significantly influenced by the laser peak power, pulse format, and wavelength. Three advanced materials are used to demonstrate the importance of choosing the correct laser parameters for a specific material. The materials are: (1) intermetallic single crystal nickel aluminide (NiAl) alloy; (2) N5, a single crystal nickel‐based superalloy; and (3) a silicon carbide (SiC) ceramic matrix composite (CMC). The laser peak power is varied in terms of the pulse...


  • JLA Vol:8 Iss:5 (Taking advantage of laser properties to enhance demonstrations and student laboratories)

    Michele L. Brill
    Camden County College — Physics/Lasers, Box 200, Blackwood, NJ 08012, U.S.A.

    This paper reflects the proceedings of a workshop for local educators provided by Camden County College Laser Curriculum faculty which addressed the question: ‘How can the teacher take advantage of laser properties to improve or enhance demonstrations and student labs?’ Explored here are illustrative ways in which to utilize, for educational purposes, the three well‐known characteristics of lasers: directionality, monochromaticity, and coherence. There is a faculty overlap between the Physics Department and the Laser Curriculum faculty at the college. The use...


  • JLA Vol:8 Iss:5 (William B. Mark Memorial Lecture)

    Kenneth A. Arndt
    Department of Dermatology, Beth Israel Hospital, 330 Brookline Ave., Boston, MA 02215, U.S.A.


  • JLA Vol:8 Iss:6 (A modeling study on the influence of pulse shaping on keyhole laser welding)

    P. S. Mohanty
    A. Kar
    J. Mazumder

    A theoretical analysis describing the effects of pulse shaping on keyhole laser welding is presented. Calculation of the keyhole profile and melt pool dimensions was performed by the balancing of surface forces and energy at the liquid‐vapor and solid‐liquid interfaces in three dimensions. The effect of temporal pulse shape on weld dimensions has been examined over a range of power densities, pulse times and pulse frequencies. Several pulse types (e.g., top‐hat, Gaussian, ramp‐up and ramp‐down pulses) have been considered. Pulse shaping showed significant effect on the weld dimensio...


  • JLA Vol:8 Iss:6 (Control and optimization of the laser cladding process using matrix cameras and image processing)

    F. Meriaudeau
    F. Truchetet
    Laboratoire GERE — Universite´ de Bourgogne, 12 rue de la Fonderie, 71200 Le Creusot, France

    The laser cladding process, which consists of adding a melted powder on to a substrate in order to improve or change the behavior of the material against corrosion or fatigue, involves many parameters. In order to produce good tracks some of these parameters need to be controlled during the process. We present a low cost system using two charge coupled device (CCD) matrix cameras. One camera provides surface temperature measurements while the other gives information about the powder distribution or geometric characteristics of the tr...


  • JLA Vol:8 Iss:6 (Laser surface alloying of magnesium base alloys)

    R. Galun
    A. Weisheit
    B. L. Mordike
    Institut fu¨r Werkstoffkunde und Werkstofftechnik, Technische Universita¨t Clausthal, Agricolastraße 6, D‐38678 Clausthal‐Zellerfeld, Germany

    The feasibility of the laser surface alloying of magnesium base alloys with aluminum, copper, nickel and silicon has been shown in this work. By laser alloying with these elements, using a 5 kW CO2‐laser, the hardness of several magnesium base alloys can be increased to values above 250 HV0.1. Melted depths from 700–1200 μm and alloying contents from 15–55 at % were achieved. The wear resistance of ...


  • JLA Vol:8 Iss:6 (Teaching laser principles with nitrogen laser pumped dye lasers)

    David H. Lieberman
    Physics Department, Queensborough Community College, 222‐05 56th Ave., Bayside, NY 11364‐1497, U.S.A.

    Nitrogen laser pumped dye lasers are useful aids to the understanding of the principles of lasers and also as tools for advanced undergraduate physics and chemistry laboratories. We have developed laboratory exercises that allow the students to develop necessary skills and study important principles. The students construct their own narrow linewidth dye lasers in a step‐by‐step process. First amplified spontaneous emission is studied and compared with broadband lasing. A grating is added to provide linewidth narrowing and tunabil...


  • JLA Vol:8 Iss:6 (The Influence of laser cavity gaseous impurities on the performance of an industrial CO<sub>2</sub> laser)

    C. R. Hsu
    C. E. Albright
    A. Khakhalev
    Welding Engineering, The Ohio State University

    Contamination in the cavities of high power industrial CO2 lasers is a cause of laser performance degradation. Such degradation can result in laser downtime and significant loss of productivity. The laser cavity gas supply can contribute to this contamination, but there is confusion about the level of gas impurity concentration which can cause a degradation process. The overall objective of this investigation was to study the effects of cavity gas contaminants on the performance of an industrial fast&hyphen;axial&hyphen;flow CO2 laser. A 3 kW fa...


  • JLA Vol:8 Iss:6 (Understanding high&hyphen;power fiber&hyphen;optic laser beam delivery)

    Boyd V. Hunter
    Keng H. Leong
    Carl B. Miller
    James F. Golden
    Robert D. Glesias
    Patrick J. Laverty

    Fiber&hyphen;optic beam delivery is commonly used in industrial laser systems. This article examines the conditions for the optimal propagation of high power beams through optical fibers. Beam quality effects by step and gradient index fibers of different lengths are considered. The differences between the diverging beam from a fiber and the beam at focus and on the fiber face are illustrated. Estimates are provided of the worst&hyphen;case beam quality to be expected from fibers. Guidelines are also provided for th...


  • JLA Vol:8 Iss:6 (Welding of aluminum: A challenging opportunity for laser technology)

    Friedrich Dausinger
    Ju¨rgen Rapp
    Markus Beck
    Frank Faisst
    Ru¨diger Hack
    Helmut Hu¨gel
    Universita¨t Stuttgart, Institut fu¨r Strahlwerkzeuge (IFSW), Pfaffenwaldring 43, D&hyphen;70569 Stuttgart, Germany

    The increasing demand for lightweight structures has led to a greater industrial use of aluminum alloys. The application of these materials is handicapped by a lack of productivity and reliability in the joining techniques currently available. The laser welding of aluminum is markedly more difficult than for steel. The difficulties to be solved include the threshold for deep penetration welding...



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