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


    Authors:
    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...

    $25.00

  • JLA Vol:20 Iss:3 (Three-dimensional biomimetic microchannel network by laser direct writing)


    Authors:
    Dong Hyuck Kam
    Jyoti Mazumder
    Center for Lasers and Plasmas for Advanced Manufacturing (CLPAM), University of Michigan, Ann Arbor Michigan 48105


    Application of laser direct writing to the fabrication of microchannel networks for tissue engineering was presented. A Q-switched Nd:YAG laser with fundamental wavelength was used. Multidepth, multiwidth microstructures on silicon were machined without photolithography-based methods. The molten material inside the microchannel was ejected with a modified assist gas, and thus the volume of laser ablation was increased. The debris build-up due to the strong thermal reaction of silicon to the nanosecond IR laser pulse was ...

    $25.00

  • JLA Vol:9 Iss:3 (In‐process monitoring of laser welding by the analysis of ripples in the plasma emission)


    Authors:
    Kiyokazu Mori
    Isamu Miyamoto



    A novel in‐process monitoring system employing two detectors set above the workpiece at different aiming angles of 5° and 75° has been developed to detect whether or not CO2 laser welding fully penetrates through to the back surface of steel sheets. The acquired signal contained a.c. components of the emission of the laser‐induced plasma in the plume and in the keyhole with frequencies up to approximately 10 kHz. The mean square value of the a.c. signal obtained by using the 75° sensor during full penetration welding was much larger than that of the partial penetration welding, showing that full p...

    $25.00

  • JLA Vol:4 Iss:1 (Laser Surfacing of High Density Polyethylene for Reduction in Fuel Permeability)


    Authors:
    W. W. Duley
    M. Ogmen
    T. Steel
    S. Mihailov



    The effect of UV and CO2 laser radiation on the surface of HDPE gas tank material in relation to the permeability of this surface to unleaded gasoline has been investigated. It is found that while excimer (UV) laser radiation has no effect on permeability, CO2 laser radiation at low intensity modifies the surface so as to reduce permeability over timescales of 1 – 2 days. A possible origin for this modification is suggested.

    $25.00

  • JLA Vol:14 Iss:4 (Process study for laser-induced surface coloration)


    Authors:
    H. Y. Zheng
    G. C. Lim
    X. C. Wang
    J. L. Tan
    Gintic Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075

    James Hilfiker
    J. A. Woollam Company, Inc., 645 M Street, Suite 102, Lincoln, Nebraska 68508


    A KrF excimer laser beam is used to induce controllable and high-contrast colors on a stainless-steel surface under different processing conditions. The laser beam acts as a localized heating source that promotes the formation of semitransparent oxide films of varying thicknesses and morphologies on the sample surface. Ellipsometry and atomic force microscopy were employed to understand the laser-induce...

    $25.00

  • JLA Vol:24 Iss:5 (Flexible and efficient laser remote welding of ultra-thin metal foils)


    Authors:
    Andreas Patschger
    Jens Bliedtner
    University of Applied Science Jena, Carl-Zeiss-Promenade 2, Jena 07745, Germany

    Matthias Hild
    JENOPTIK Automatisierungstechnik GmbH, Konrad-Zuse-Straße 6, Jena 07745, Germany

    Jean Pierre Bergmann
    University of Technology Ilmenau, Neuhaus 1, Ilmenau 98693, Germany


    This paper discusses investigations regarding flexible and efficient strategies of laser remote welding of ultra-thin metal foils (≤50 μm) which are applied in the fields of electronics, packaging, and construction. A single-mode fiber laser was used, equipped with a scanner head and diverse objectives. Thus...

    $25.00

  • JLA Vol:18 Iss:4 (Simulated fabrication of off-axis microlens array using excimer laser dragging process)


    Authors:
    Shuh-Yi Wang
    Department of Mechanical Engineering, Chengshiu University, 840 Cheng Ching Road, Niaosung, Kaoushiung, 833, Taiwan, Republic of China


    A computer simulation of the fabrication of an off-axis aspheric microlens array using excimer laser dragging with variously shaped masks is performed. Traditionally, a semicircular mask is used during dragging to yield an on-axis microlens array. However, a quarter-circular mask can generate an off-axis microlens array using this dragging process. Unlike the more common centered or on-axis system, this off-axis microlens array can process focused light without obstructing the lens. Variously shaped masks were computer simulated. ...

    $25.00

  • JLA Vol:23 Iss:4 (Femtosecond laser machined microfluidic devices for imaging of cells during chemotaxis)


    Authors:
    L. Costa
    A. Terekhov
    D. Rajput
    W. Hofmeister
    Center for Laser Applications, University of Tennessee Space Institute, Tullahoma, Tennessee 37388

    D. Jowhar
    G. Wright
    Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37240

    C. Janetopoulos
    Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37240 and Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee 37240


    Microfluidic devices designed for chemotaxis assays were fabricated on fused silica substrates using femtosecond laser micromachining. These devices hav...

    $25.00

  • JLA Vol:6 Iss:1 (Standardization in the field of lasers in Europe—Towards common international standards)


    Authors:
    Ernst Sutter
    Physikalisch‐Technische Bundesanstalt, Bundesallee 100, D‐38116 Braunschweig, Germany


    Different standards in different European countries have given rise to technical trade barriers. The European Community made a great effort to establish a single market before the end of 1992 in which the free movement of goods is ensured. The first approach was to adopt directives setting up detailed requirements for all products. This has proved to be such a slow and difficult process that the New Approach has been adopted: the essential requirements are established by directives, whereas the technical specifications are detailed in harmonized standards....

    $25.00

  • JLA Vol:17 Iss:2 (Numerical simulation of femtosecond laser interaction with silicon)


    Authors:
    Hyungson Ki
    Mechanical Engineering Department, Michigan State University, East Lansing, Michigan 48824-1226

    Jyoti Mazumder
    Center for Laser Aided Intelligent Manufacturing, University of Michigan, Ann Arbor, Michigan 48109-2125


    A numerical model for simulating femtosecond laser interaction with silicon is presented. This model simulates laser beam propagation by directly solving Maxwell’s equations using the finite-difference time-domain method, so that complete electromagnetic nature of a laser beam is simulated accurately. Accurate computation of laser beam passage ensures realistic heat generation pattern in the target material. The two-temperat...

    $25.00

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