• JLA Vol:24 Iss:4 (Femtosecond laser welded nanostructures and plasmonic devices)


    Authors:
    A. Hu
    P. Peng
    H. Alarifi
    X. Y. Zhang
    J. Y. Guo
    Y. Zhou
    W. W. Duley
    Array


    Nanojoining, a burgeoning research area, becomes a key manufacturing of complicated nanodevices with functional prefabricated components. In this work, various nanojoining methods are first reviewed. For nanojoining of Ag/Au nanoparticles, three methods are investigated comparatively. Thermal annealing shows a two-step solid state diffusion mechanism. Laser annealing by millisecond pulses displays the thermal activated solid state diffusion. Meanwhile, two effects have been identified in femtosecond laser irradiation with diffe...

    $25.00

  • JLA Vol:5 Iss:2 (Characterization of Laser Produced High Molybdenum Surface Alloys on Stainless Steel Substrates)


    Authors:
    Dilip Kumar
    K. Sridhar
    A. R. Biswas
    G. L. Goswami
    M. B. Deshmukh



    High Mo surface alloys on stainless steels 304L and 316L were produced by laser surface alloying. For this, a layer of 60 μm thickness was overlaid on the substrates by plasma spraying of Mo powders. These were further treated by a Nd:YAG pulsed laser for alloying. Depths of alloying in the range of 440–1110 μm were achieved. Concentration in the range of 5.2–15.0 wt% Mo within the laser alloyed zone was, in general, uniform throughout. During alloying, in‐situ heating at 700°C was required to prevent cracking in samples wi...

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  • 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...

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  • 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 ...

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  • JLA Vol:7 Iss:1 (Photodynamic therapy)


    Authors:
    Leonard I. Grossweiner
    Physics Department, Illinois Institute of Technology, Chicago, IL 60616 and Wenske Laser Center, Ravenswood Hospital Medical Center, Chicago, IL 60664, U.S.A.


    Photodynamic therapy (PDT) is a new treatment for solid tumors utilizing the combined action of light and a photosensitizing drug. Laser–fiber optic delivery systems make it practical to treat superficial and interstitial cancers, including malignancies of the skin, head and neck, esophagus, endobronchial tract, stomach, urinary bladder, female genital tract, and other sites. The putative action mechanism in PDT involves photochemical destruction of tumor tissue membranes mediated by singlet...

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  • 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...

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  • 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. ...

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  • 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...

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  • 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...

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  • 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

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