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  • JLA Vol:7 Iss:3 (Characterization of chromium bearing surface alloys produced by laser alloying on low carbon steel substrates)


    Authors:
    G. L. Goswami
    Dilip Kumar
    A. L. Pappachan
    A. K. Grover
    K. Sridhar
    Array


    High‐chromium ferritic alloys were produced on mild steel substrates by laser surface alloying. For this, chromium‐plated mild steel samples were treated with a pulsed Nd:YAG laser (300 W maximum power) by varying the average power level from 21.6 W to 30.0 W. The chromium content of the surface alloys was in the range of 3.0–27.0 wt%, with fairly uniform depth of alloying. Microscopy showed very fine austenite needles within elongated/equiaxed ferrite grains in the laser‐alloyed zone (LAZ). X‐ray diffraction indi...

    $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...

    $25.00

  • JLA Vol:25 Iss:1 (Implementation of a novel scan localization system for wireless sensor networks)


    Authors:
    K. Sun
    W. Huang
    Sachula Meng
    Y. Xiao
    M. T. Wang
    Z. Xiao
    Inner Mongolia University, Hohhot 010021, China


    A novel localization scheme called laser beam scan localization by combining grid and light (laser) with mobile localization policy for wireless sensor networks is designed. The scheme utilizes a moving location assistant (LA) with a laser beam, through which the deployed area is scanned. The LA sends identities to unknown nodes to obtain the locations of sensor nodes. High localization accuracy can be achieved without the aid of expensive hardware on the sensor nodes, as required by other localization systems...

    $25.00

  • 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:23 Iss:4 (Evaluation of the bone repair in defects grafted with hydroxyapatite and collagen membrane combined with laser therapy in rats)


    Authors:
    Marcelo Rodrigues da Cunha
    Luanda de Abreu Figueira
    Joa˜o Paulo Mardegan Issa
    Ricardo Alexandre Junqueira Calzzani
    Daniele Cristina do Prado Ribeiro
    Amilton Iatecola
    Mariane Silva Pettian
    Array


    Bone regeneration is the result of cellular events such as osteogenesis and neovascularization. However, implantation of autogenous grafts may be necessary in cases of bone mass loss due to high impact trauma. The disadvantages of the latter approach include morbidity of the donor area. Biomaterials represent an alternative for bone restoration. The most widely used compounds are collagen or hydroxyapat...

    $25.00

  • JLA Vol:6 Iss:2 (CO<sub>2</sub> shielding gas effects in laser welding mild steel)


    Authors:
    D. H. Abbott
    C. E. Albright



    The most widely used shielding gases for laser welding of steels are helium and argon. Helium produces significantly more penetration than argon in penetration&hyphen;mode laser beam welding. Another gas that has been proposed as an alternative to these inert gases is carbon dioxide. The benefits of using carbon dioxide as a shielding gas for laser welding are that it costs less than helium and argon and that it provides nearly the same penetration as helium. The major drawback to its use as a shielding gas for mild steel is that it can cause porosity and other weld discontinuities. In this investigation helium and carbon dioxide were...

    $25.00

  • JLA Vol:17 Iss:3 (Laser beam analysis in direct metal deposition process)


    Authors:
    Huan Qi
    Jyoti Mazumder
    Center for Laser Aided Intelligent Manufacturing, Department of Mechanical Engineering, The University of Michigan, Ann Arbor, Michigan 48109

    Larry Green
    Spiricon, Inc., Logan, Utah 84341

    Gary Herrit
    II-VI, Inc., Saxonburg, Pennsylvania 16056


    The quality of a laser beam profile and its stability play fundamental roles in laser material processing. Beam reflections may dramatically affect the beam quality under certain material processing conditions. In this study, experiments were carried out to examine the variations of the continuous wave CO2 laser beam profile during the direct metal...

    $25.00

  • JLA Vol:21 Iss:4 (Contributions of Charles Townes&rsquo; research to nonlinear optics)


    Authors:
    Elsa Garmire
    Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755, USA


    Nonlinear optics was profoundly influenced by early work of Charles Townes and his group at Massachusetts Institute of Technology from 1961 to 1967. His foundational contribution was the realization that coherent molecular oscillations resulted from stimulated Raman scattering, leading to the introduction of stimulated Brillouin scattering. Self-trapping of light beams and self-steeping of light pulses in nonlinear materials were two other important innovations. Some applications today of these early ideas are outlined.

    $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&hyphen;of&hyphen;concept testing or process development. Located at Wright&hyphen;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&percnt;). Copies of the grating formed in PMMA (acrylic) survived preliminary life tests (more than 1000 9&hyphen;J pulses from a commercial multimode N...

    $25.00

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