• 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 &...


  • JLA Vol:15 Iss:4 (Excimer laser fabrication of polymer microfluidic devices)

    Joohan Kim
    Xianfan Xu
    School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907

    Silicon has been a primary material for fabrication of microelectromechanical systems (microfluidic devices in MEMS) for several decades. This is due to the fact that the MEMS techniques were derived from those used for microfabrication in the semiconductor industry. These techniques are well developed, and can be readily applied for silicon based MEMS fabrication. Nowadays, alternative manufacturing materials and techniques are needed for reducing costs and meeting new requirements. Polymers have many advantages because of their low costs and applications in ...


  • JLA Vol:8 Iss:3 (Laser shock processing of materials, physical processes involved and examples of applications)

    P. Peyre
    R. Fabbro
    L. Berthe
    C. Dubouchet

    Laser shock processing (LSP) consists of irradiating a metallic target with a short (about 20 ns) and intense (>1013W m−2) laser light in order to generate, through a high pressure surface plasma (>1 GPa), a plastic deformation and a surface strengthening within materials. This paper initially reviews the physical processes involved in the analytical modeling of the generation pressure mechanism in a confined plasma regime. Limiting factors such as the dielectric breakdown in the confining medium are also discussed together with current research directions aimed...


  • JLA Vol:2 Iss:3 (On Optical Methods in Particle Flow)

    I. Shimizu
    Dept. of Mechanical Engineering, Ibaraki College of Technology, Katsuta 312, Japan

    Wen‐Jei Yang
    Dept. of Mech. Eng. and Applied Mech., University of Michigan, Ann Arbor, Michigan 48109

    Some recently developed optical methods for the measurement, control and shape recognition of particle flow are presented including motion control of micro‐particles by optical pressure, identification of particle groups by matched spatial filters, bidirectional light scattering/image processing, bidirectional light scattering/real time measurement, dual beam type particle counter, and speckle photography.


  • JLA Vol:14 Iss:1 (Particle size analysis of material removed during CO<sub>2</sub> laser scabbling of concrete for filtration design)

    L. M. Lobo
    K. Williams
    Optical Engineering Group, Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU, United Kingdom

    E. P. Johnson
    Laser Group, Department of Mechanical Engineering, Liverpool University, Liverpool, Merseyside L69 3BX, United Kingdom

    J. T. Spencer
    BNFL, Rutherford House, Risley, Warrington, Cheshire WA3 6AS, United Kingdom

    This article examines the particles formed during optimized laser scabbling of concrete in order to help determine an effective filtration strategy for the process. The laser scabbling technique has been developed ...


  • JLA Vol:18 Iss:2 (CO<sub>2</sub> laser beam cutting of steels: Material issues)

    Murali Manohar
    Mittal Steel USA R&D, East Chicago, Indiana 46312

    Laser beam cutting and its advantages along with its relevance to worldwide trends in manufacturing are introduced. Results of efforts to identify material-related factors that render steel suitable for laser cutting are described. Key material requirements for both hot-strip and discrete plate products have been summarized using data collected over several years based on anecdotal information as well as experimental results. It has become clear that near-zero residual stresses and a minimum level of residual elements (Cu, Ni, and Cr) are necessary to obtain clean pierces and consistent cut quality in thick ...


  • JLA Vol:24 Iss:4 (Optical trap assisted laser nanostructuring in the near-field of microparticles)

    Ulf Quentin
    Karl-Heinz Leitz
    Lutz Deichmann
    Ilya Alexeev
    Michael Schmidt

    Particle based near-field nanostructuring is an excellent possibility to overcome the optical diffraction limit in laser based material processing. In the near-field of microspheres which are irradiated with pulsed laser radiation, it is possible to generate nanoholes with diameters below 100 nm using a laser wavelength of 800 nm. To improve this approach, it is possible to position the microparticles with an optical trap to generate arbitrary structure geometries. In this paper, the authors describe the basic principle of optical trap assisted na...


  • JLA Vol:5 Iss:2 (Tutorial Guide: Laser Measurement Techniques Guide For Hazard Evaluation. Part 2)

    Terry Lyon
    Laser Microwave Division, U.S. Army Environmental Hygiene Agency

    A tutorial guide is presented to provide uniform guidance when performing radiometric measurements upon laser systems to perform a hazard evaluation. This guide was requested by and presented to the Department of Defense (DOD) Laser System Safety Working Group (LSSWG) to serve as a standardized method when performing hazard evaluations primarily upon tactical and training military laser systems including laser rangefinders and designators. Technical information is provided in detail to select a suitable detector, preform radiometric measurements, assess laser system pointing errors, calculate laser p...


  • JLA Vol:16 Iss:2 (Foam coating on aluminum alloy with laser cladding)

    V. Ocelı´k
    V. van Heeswijk
    J. Th. M. De Hosson
    Department of Applied Physics, Material Science Center and The Netherlands Institute for Metals Research, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands

    K. Csach
    Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 043 53 Košice, Slovakia

    This article concentrates on the creation of a foam layer on an Al–Si substrate with laser technology. The cladding of Al–Si powder in the front of a laser track has been separated from the side injection of mixture of Al–Si/TiH2 powder (foaming agent),...


  • JLA Vol:20 Iss:4 (Keyhole welding studies with a moderate-power, high-brightness fiber laser)

    R. T. Brown
    Robert T. Brown, LLC, Technical Consulting, 74 South Farms Drive, Manchester, Connecticut 06040 and Department of Mechanical Engineering, University of Hartford, West Hartford, Connecticut

    Bead-on-plate welding tests were performed using a 600 W fiber-delivered fiber laser. Uniform, high-aspect-ratio keyhole welds were observed in 1018 low-carbon steel, 1100 aluminum, and 304 stainless steel. The Rosenthal two-dimensional thermal model for a moving-line heat source was effective in predicting weld width for both partial-penetration and full-penetration welds. By setting the temperature at the perimeter of the keyhole equal to the vaporization temperature, thi...



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