• JLA Vol:7 Iss:2 (Understanding laser hazard evaluation)

    Wesley J. Marshall
    U.S. Army Center for Health Promotion and Preventive Medicine (Provisional), Aberdeen Proving Ground, MD 21010‐5422, U.S.A.

    The current 1993 version of the ANSI Z136.1 standard for the safe use of lasers provides maximum permissible exposures which more closely match available biological injury data. Interpreting the standard can be more difficult at times than with previous versions. By keeping the biological injury mechanism in mind, the reasoning behind the multitude of rules contained in the standard are more understandable.


  • JLA Vol:16 Iss:3 (Methods for hazard assessment from viewing fiber optics with eye loupes)

    Wesley J. Marshall
    U.S. Army Center for Health Promotion and Preventive Medicine, Aberdeen Proving Ground, Maryland 21010-5403

    John Bell
    Terabeam Corporation, Redmond, Washington

    David H. Sliney
    U.S. Army Center for Health Promotion and Preventive Medicine, Aberdeen Proving Ground, Maryland 21010-5403

    Current laser safety standards overestimate retinal hazards when viewing optical fiber tips with magnifying aids. Methods for assessing optical hazards are based on laser beam characteristics and assume worst-case exposure to both the unaided eye and when using a variety of optical aids. These standard methods provide overly conservati...


  • JLA Vol:21 Iss:1 (Two-laser deflashing of heat sinks in integrated circuit packages)

    W. D. Song
    Q. Xie
    Data Storage Institute, Agency of Science, Technology and Research, DSI Building, 5, Engineering Drive 1, Singapore 117608, Singapore

    During the plastic packaging process, mold flash is usually formed on a heat sink. In order to keep efficient heat transfer from the integrated circuit device to the exterior environment, the mold flash must be removed from the heat sink surface. In this paper, we demonstrate that a Nd:YAG laser deflashing is only available to remove thin flash of a few micrometers from heat sinks and cannot remove thick flash without damage to the heat sink, both from experimental and numerical analysis. Based on optical and ther...


  • JLA Vol:9 Iss:5 (Characteristics of Nd:YAG laser welded high carbon steels)

    Eng S. Ng
    Ian A. Watson
    Laser and Optical System Engineering Centre, Department of Mechanical Engineering, James Watt Building, University of Glasgow, Glasgow G12 8QQ, U.K.

    A quantitative study of the relationship between the laser process parameters and the mechanical properties of welded high carbon steels was performed utilizing a Lumonics Nd:YAG pulsed laser, operating at 1.06μm, and a robotically manipulated fiber optic beam delivery system. A gage plate (0.88 mm thick) was butt welded with a constant power of 200 W and a He shielding gas was used at a pressure of 5 × 104 Pa. The welding performance of the Nd:YAG laser was strongly affect...


  • JLA Vol:3 Iss:3 (The Role of Oxidation in Laser Cutting Stainless and Mild Steel)

    A. Ivarson
    J. Powell
    C. Magnusson

    This paper gives the results of a detailed examination of the particles ejected from the cut zone during CO2 laser cutting of mild and stainless steels. Cuts were carried out over a range of material thickness at the optimum speed for each at a laser power of 900 Watts. Particles ejected from the cut zone were collected and analyzed to establish their chemical and physical characteristics. Analysis techniques included Scanning Electron Microscopy, wet chemical analysis, optical microscopy, metallography and particle sizing. The results from this extensive analysis have enabled the authors to estimate the...


  • JLA Vol:25 Iss:3 (The influence of position in overlap joints of Mg and Al alloys on microstructure and hardness of laser welds)

    S. Bannour
    Unite´ de Thermique et Thermodynamique des Proce´de´s Industriels, Ecole Nationale d'Inge´nieurs de Monastir, Avenue Ibn Jazzar, 5019 Monastir, Tunisia and Institut de Me´canique de Marseille, Laboratoire IUSTI, UMR CNRS 6595, Universite´ de la Me´diterrane´e—Aix-Marseille Universite´, Technopoˆle de Chaˆteau- Gombert, 60 rue Joliot Curie, 13453 Marseille Cedex 13, France

    K. Abderrazak
    Unite´ de Thermique et Thermodynamique des Proce´de´s Industriels, Ecole Nationale d'Inge´nieurs de Monastir, Avenue Ibn Jazzar, 5019 Monastir, Tunisia

    S. Mattei


  • JLA Vol:15 Iss:1 (Deposition of WC/Ni clad layers with a pulsed Nd:YAG laser)

    M. Brandt
    Industrial Research Institute Swinburne, Swinburne University of Technology, Melbourne Vic 3122, Australia

    S. W. Huang
    M. Samandi
    Department of Materials Engineering, Surface Engineering Research Centre (SERC), University of Wollongong, NSW 2522, Australia

    A series of experiments was performed to investigate the production of WC/Ni clad layers on H13 tool steel using a pulsed Nd:YAG laser and optical fibers. The effects of laser parameters, such as laser pulse energy and pulse frequency as well as material parameters such as powder composition and shape on the clad layer geometry and microstructure, were investigated. The microstru...


  • JLA Vol:19 Iss:1 (Procedure for the computation of hazards from diffusely scattering surfaces under the Z136.1-2000 American National Standard for Safe Use of Lasers)

    Robert J. Thomas
    Benjamin A. Rockwell
    Air Force Research Laboratory, Brooks AFB, Texas 78235-5128

    Wesley J. Marshall
    USACHPPM, Aberdeen Proving Ground, Maryland 21010-5403

    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

    The current national consensus standard for laser safety in the United States is the American National Standard for Safe Use of Lasers (ANSI Z136.1). The most recent standard, Z136.1-2000, incorporates ...


  • JLA Vol:24 Iss:1 (Hazard class downscaling of a class 4 retina safe laser)

    Jed A. Simmons
    Alan B. Marchant
    Energy Dynamics Laboratory, North Logan, Utah 84341

    A class 4 pulsed laser can be operated in a safe regime without reducing instantaneous irradiance or pulse energy by shortening its dwell time through duty cycle reduction or scanning. A conservative relationship for hazard distance as a function of scan rate is derived for the case of a scanning, retina safe laser.


  • JLA Vol:6 Iss:3 (Attenuation of laser radiation by particles during laser materials processing)

    F. Hansen
    W. W. Duley
    Guelph‐Waterloo Centre for Graduate Work in Physics, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1

    The extinction, absorption and scattering of laser radiation by small aerosol particles of Fe, Fe3O4, Al, and Al2O3 have been calculated using Mie theory at wavelengths of 1.06 and 10.6 μm. It is shown that the attenuation of incident laser radiation by particles with radii r in the range 10 nm ⩽ r ⩽ 10 μm can be significant over pathlengths as small as 10−2 m when the ratio of aerosol mass density to solid density, M/ρ &...



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