• JLA Vol:24 Iss:2 (Laser dressing of metal bonded diamond blades for cutting of hard brittle materials)


    Authors:
    Philipp von Witzendorff
    Anas Moalem
    Rainer Kling
    Ludger Overmeyer
    Laser Zentrum Hannover e.V., Hollerithallee 8, 30419 Hannover, Germany


    In this study, the authors investigate the laser dressing of metal bonded diamond blades by means of laser pulses with different pulse durations and wavelengths. Conventional dressing suffers from excessive blade wear, whereas laser dressing enables precise removal of the bonding metal to generate the required chip space of protruding diamond grains. The challenge for processing this composite material is to find appropriate level of ablation for the bonding metal without damaging the diamond grains thr...

    $25.00

  • JLA Vol:6 Iss:3 (Safety concerns about laser pointers)


    Authors:
    David H. Sliney
    Jerome E. Dennis



    In the past two years considerable concerns have been expressed about the safety of Class 3A laser pointers. The concern has been that Class 3A diode–laser pointers have replaced the safer helium–neon (He–Ne) Class 2 laser pointers. Hundreds of thousands of small He–Ne visible‐wavelength lasers have been traditionally used for alignment and pointing, laser demonstrations and laser displays in science, education and industry, but can the diode laser be as safe and effective? Not infrequently, some people associate “lasers” with Buck Rogers and “Star Wars”, and are concerned wh...

    $25.00

  • JLA Vol:8 Iss:3 (Laser Hardened Materials Evaluation Laboratory (LHMEL))


    Authors:
    R. J. Hull
    M. L. Lander



    Since 1976, the Laser Hardened Materials Evaluation Laboratory (LHMEL) has been characterizing material responses to laser energy in support of national defense programs and the aerospace industry. Now that capability is available to commercial industry as well. LHMEL's power levels, beam uniformity, and diagnostics capabilities make it an ideal facility for proof‐of‐concept testing or process development. Located at Wright‐Patterson Air Force Base, Ohio, LHMEL is managed by the Wright Laboratory Materials Directorate and operated by Lawrence Associates, Incorporated. The facility's advanced hardware is centered aroun...

    $25.00

  • JLA Vol:2 Iss:2 (Binary Phase Gratings for Materials Processing)


    Authors:
    Paul J. Patt
    Array


    The feasibility of using a diffractive optical element, a phase grating, as a beam handling device for use in industrial laser material processing is examined. The binary phase grating is an efficient beam splitting device and is useful in many materials processing operations (welding, cutting, soldering, drilling) where a high degree of parallelism could significantly improve process throughput. Overall efficiency of etched quartz binary gratings agrees well with published predictions (nominal 70–90%). Copies of the grating formed in PMMA (acrylic) survived preliminary life tests (more than 1000 9‐J pulses from a commercial multimode N...

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  • JLA Vol:25 Iss:5 (Heat transfer and fluid flow in additive manufacturing)


    Authors:
    A. Raghavan
    H. L. Wei
    T. A. Palmer
    T. DebRoy
    Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802


    In laser-based direct energy deposition additive manufacturing, process control can be achieved through a closed loop control system in which thermal sensing of the melt pool surface is used to adjust laser processing parameters to maintain a constant surface geometry. Although this process control technique takes advantage of important in-process information, the conclusions drawn about the final solidification structure and mechanical properties of the deposited material are li...

    $25.00

  • JLA Vol:14 Iss:4 (Visible and invisible laser radiation—problems in laser safety terminology)


    Authors:
    David H. Sliney
    U.S. Army Center for Health Promotion and Preventive Medicine, Aberdeen Proving Grounds, Maryland 21010

    David J. Lund
    U.S. Army Medical Research Detachment, Brooks Air Force Base, Texas 78235

    Wesley J. Marshall
    U.S. Army Center for Health Promotion and Prevention Medicine, Aberdeen Proving Grounds, Maryland 21010


    The spectral band between 400 and 700 nm is termed “visible” in laser safety standards, this is not the full extent of the visible spectrum. Light, or visible radiation, is that which is perceived by the human eye, and the spectral bandwidth for vision is really larger, extending into what some r...

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  • JLA Vol:19 Iss:1 (Three-dimensional numerical approach for geometrical prediction of multilayer laser solid freeform fabrication process)


    Authors:
    Masoud Alimardani
    Ehsan Toyserkani
    Jan P. Huissoon
    Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada


    This article presents the development of a three-dimensional numerical method for predicting transient geometrical and thermal characteristics of multilayer laser solid freeform fabrication as a function of process parameters and material properties. In the proposed method, the thermal domain is numerically obtained, assuming the interaction between the laser beam and powder stream is to be decoupled. Once the melt pool boundary is obtained, the physical domain is discretized in a cross-se...

    $25.00

  • JLA Vol:24 Iss:4 (Laser-assisted nanofabrication of carbon nanostructures)


    Authors:
    Yun Shen Zhou
    Wei Xiong
    Jongbok Park
    Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0511, USA

    Min Qian
    Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, 68588-0511, USA and Department of Physics, East China Normal University, Shanghai 200062, People’s Republic of China

    Masoud Mahjouri-Samani
    Yang Gao
    Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0511, USA

    Lan Jiang
    Department of Mechanical and Automation Engineering, Beijing Institute of Technology, Bei...

    $25.00

  • JLA Vol:5 Iss:1 (Heat Flow in Laser Die Blank Welding)


    Authors:
    Y.‐S. Yang
    C. R. Hsu
    C. E. Albright
    Y. Kuroda



    Laser welded die blanks are finding increased usage in many industrial applications. This investigation was undertaken to establish a simplified means of calculating thermal cycles experienced in the fusion and heat affected zones on laser welds typically used in die blank welding. A planar solution domain perpendicular to the direction of travel was selected to simplify the finite element calculations. The resulting calculation technique provided reasonably accurate prediction of the thermal cycles measured by Moon and Metzbower, and the size of fusion zones and heat affected zones o...

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  • JLA Vol:1 Iss:3 (CO<sub>2</sub> Laser Engraving System for Relief Plate to Print Corrugated Cardboard)


    Authors:
    K. Wakabayashi
    N. Sugishima
    NEC Corporation, Laser Equipment Div., 1120, Shimokuzawa, Sagamihara, JAPAN


    A very compact and economical CO2 laser engraving system to make relief plates for the purpose of printing corrugated cardboard has been developed. This system consists of a highly stable 500W CO2 laser and a high speed, easy handling image processing sub&hyphen;system. In this paper several new developments are described. This image processing technique for CO2 laser raster scanning and engraving has been newly developed. Every binary image is converted to the relief plate more easier than other reported engraving systems.

    $25.00

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