• JLA Vol:6 Iss:1 (Effects of process parameters on the fatigue strength of laser beam welds)


    Authors:
    P. C. Wang
    K. M. Ewing



    An experimental study, augmented by three‐dimensional finite element analysis, was performed to assess the effects of various process parameters such as presence of galvanized coating, welding speed and weld geometry (weld start and stop, metal fit‐up, and weld orientation) on the fatigue resistance of laser beam welds. It was found that the fatigue resistance of laser beam welds depends upon the welding speed used and weld geometry. With a 2.75 kW CO2 laser and at a welding speed of 38.1 mm s−1, the resultant laser beam welds gave the highest fatigue resistance. For a continuous weld, maintaining ...

    $25.00

  • JLA Vol:14 Iss:3 (Laser-assisted chemical etching for embedded microchannels and overhanging microstructures on Si/SiO<sub>2</sub> substrates)


    Authors:
    George P. Vakanas
    Array

    Ampere A. Tseng
    Department of Mechanical and Aerospace Engineering, Arizona State University, Tempe, Arizona 85287

    Paul Winer
    Silicon Debug Tools Development, SC9-09, Intel Corporation, Santa Clara, California 95054


    The feasibility of fabricating buried (embedded or subsurface) microstructures between silicon and silicon oxide using laser-assisted chemical etching (LACE) in chlorine atmosphere is demonstrated in this article. An associated LACE ablation model and sample calculations based on one-dimensional thermal analysis and chemical kinetics are presented. A strategy for optimizing the laser process for 3...

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  • JLA Vol:18 Iss:3 (Optimization of optical density requirements for multiwavelength laser safety)


    Authors:
    Kristy L. Hayes
    Robert J. Thomas
    Air Force Research Laboratory, 2624 Louis Bauer Drive, Brooks City-Base, Texas 78235

    Richard E. Pingry
    Northrop Grumman Corporation, IT Division, 7067 Buckeye Road, Roanoke, Virginia 24018


    Multiwavelength laser exposures pose unique safety challenges for both laser experts and users of laser systems. We describe two methods of optimizing optical density requirements for multiwavelength laser exposures. The problem is first formulated and solved using standard mathematical programming techniques, and the results are compared to those from a simplified algorithm. The result is a method that can be efficiently i...

    $25.00

  • JLA Vol:8 Iss:2 (Obtaining laser safety at a synchrotron radiation user facility: The Advanced Light Source)


    Authors:
    Kenneth Barat
    Lawrence Berkeley National Laboratory, MS 90&hyphen;2148, 1 Cyclotron Road, Berkeley, CA 94720, U.S.A.


    The Advanced Light Source (ALS) is a United States national facility for scientific research and development located at the Lawrence Berkeley National Laboratory in California. The ALS delivers the world's brightest synchrotron radiation in the far ultraviolet and soft X&hyphen;ray regions of the spectrum. As a ‘user facility’ it is available to researchers from industry, academia, and laboratories from around the world. Subsequently, a wide range of safety concerns become involved. This article relates not only to synchrotron facilities but to any ...

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  • JLA Vol:17 Iss:1 (Excimer laser ablation of glass-based arrayed microstructures for biomedical, mechanical, and optical applications)


    Authors:
    Ying-Tung Chen
    Department of Mechanical Engineering, Chung Cheng Institute of Technology, Tashi, Taiwan 33508, Republic of China

    Kung-Jeng Ma
    Department of Mechanical Engineering, Chung Hua University, Hsinchu, Taiwan 30067, Republic of China

    Jack G. Zhou
    Department of Mechanical Engineering, Drexel University, Philadelphia, Pennsylvania 19104

    Ampere A. Tseng
    Department of Mechanical and Aerospace Engineering, Center for Solid State Electronics Research, Arizona State University, Tempe, Arizona 85287-6106


    An excimer laser has been used for ablation of glass-based substrates for making arrayed microstructures. T...

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  • JLA Vol:21 Iss:3 (Shear bond stress of composite bonded to excimer laser treated dentin)


    Authors:
    M. Sivakumar
    V Oliveira
    R. Vilar
    Depto. Engenharia Materiais, Instituto Superior Te´cnico, Universidade Te´cnica Lisboa, Av. Rovisco Pais n. 1, 1049-001 Lisboa, Portugal

    S. Oliveira
    Faculdade Medicina Denta´ria, Universidade Lisboa, Cidade Universita´ria, 1648-003 Lisboa, Portugal


    The aim of this work was to study the bond strength of resin composite bonded to dentin surfaces treated with KrF excimer laser radiation, untreated surfaces, and acid-etched surfaces using a single-plane shear method. Dentin specimens cut from freshly extracted permanent molar teeth were subjected to laser treatment with a KrF ...

    $25.00

  • JLA Vol:24 Iss:3 (Trepanning drilling of microholes on cemented tungsten carbide using femtosecond laser pulses)


    Authors:
    Khai Xuan Pham
    Rie Tanabe
    Yoshiro Ito
    Department of Mechanical Engineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan


    Microholes of 100–300 µm diameters were trepanned on cemented tungsten carbide plates of 0.5 and 1 mm thicknesses by means of femtosecond laser pulses using a galvano-scanner with an f-θ lens of 80 mm focal length. It was found that the focus position of the laser beam relative to the sample surface affects the drilled hole shape and drilling speed. Focus on the surface produced a less tapered hole and a higher machining speed than focus 0.5 mm away from the surfa...

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  • JLA Vol:6 Iss:4 (Exposure to &ldquo;lessons learned&rdquo;: A tool for laser safety)


    Authors:
    Kenneth Barat
    Susan Elisabeth Kelly
    Lawrence Berkeley Laboratory, Environment, Health & Safety Division, University of California, Berkeley, CA 94720, U.S.A.


    This article outlines the value and steps to follow for establishing a “lessons learned program”, with specific application to a laser safety program. As a communication tool and preventive measure for laser safety issues, the program is an effective means of turning accident investigation into a proactive rather than a reactive exercise by emphasizing corrective rather than disciplinary (looking for someone to blame) actions.

    $25.00

  • JLA Vol:15 Iss:3 (Experimental and numerical analyses of the mechanism for decreasing hydrogen-embrittlement sensitivity of aged Inconel 718 by laser surface annealing)


    Authors:
    Liufa Liu
    School of Materials Science and Engineering, Shanghai Jiao Tong University, Huashan Road 1954, Shanghai 200030, China

    Katsumi Tanaka
    Akio Hirose
    Kojiro F. Kobayashi
    Department of Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan


    Laser surface annealing (LSA) treatments were conducted to decrease the hydrogen embrittlement (HE) sensitivity of Inconel 718. Hydrogen was charged into the alloy by a cathodic-charging process. The LSA treatment significantly reduced the strength loss of the hydrogen-precharged notched specimen. Tensile tests and elasto–...

    $25.00

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