• 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’ 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: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: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:15 Iss:4 (Welding of thick austenitic stainless steel using Nd:yttrium&ndash;aluminum&ndash;garnet laser with filler wire and hybrid process)


    Authors:
    Tommi Jokinen
    Miikka Karhu
    VTT Industrial Systems, P.O. Box 17021, FIN 53851 Lappeenranta, Finland

    Veli Kujanpa¨a¨
    Lappeenranta University of Technology, P.O. Box 20, FIN 53851 Lappeenranta, Finland


    Autogenous laser welding has shown many advantages over traditional welding methods in numerous applications. However, there could be even more applications, but due to the power levels of present high power lasers, depth of penetration is limited. One way to overcome this limitation is to use multipass laser welding, in which a narrow gap and a filler wire are applied. By this process thick sections can be welded with a smaller heat inpu...

    $25.00

  • JLA Vol:18 Iss:1 (Cladding of Stellite-6 and vanadium carbide on carbon steel using a yttrium&ndash;aluminum&ndash;garnet laser robot system)


    Authors:
    Guojian Xu
    Graduate School of Engineering, Nagoya University, 1 Furo-cho Chikusa-ku, Nagoya 464-8603, Japan

    Muneharu Kutsuna
    Manoj Rathod
    School of Engineering, Nagoya University, 1 Furo-cho Chikusa-ku, Nagoya 464-8603, Japan


    In the present work, a laser robot system was setup for cladding and repairing machinery parts using pulsed 300 W Nd:yttrium–aluminum–garnet laser facility, six-axis robot, optical fiber, powder feeding system with a special nozzle for powder supply. A mild steel plate was deposited with powder mixtures of Stellite-6 alloy and vanadium carbide (VC). The shape of clad layer, microstructure, and its wear perfo...

    $25.00

  • JLA Vol:24 Iss:3 (Investigation of the effects of basic laser material interaction parameters in laser welding)


    Authors:
    W. J. Suder
    S. W. Williams
    Welding Engineering and Laser Processing Centre, Cranfield University, MK43 0AL, United Kingdom


    The depth of penetration achieved in continuous wave (CW) laser welding results from a balance of many complicated phenomena, which are linked with the characteristics of the heat source. In this work, the laser welding process has been investigated in terms of basic laser material interaction parameters: power density and interaction time. It has been shown that these two parameters are insufficient to characterize the laser welding process. Thus, a third parameter, specific point energy, has been introduced, which along with the power densi...

    $25.00

  • JLA Vol:6 Iss:4 (Effective laser applications in high school physics)


    Authors:
    Jeff Sweet
    North Salinas High School Salinas, CA 93906, U.S.A.


    Laser light is an instant attention&hyphen;getter in the classroom; thus any activity which uses the laser as an instructional tool is sure to enhance student motivation. This paper discusses two demonstrations and one experiment involving laser applications that the author has found to be particularly beneficial in terms of (1) instructional effectiveness and (2) arousing the interest of high school physics students. Brief descriptions follow. Refraction through lenses can be nicely illustrated by splitting laser light into several parallel beams and directing them through a fish tank filled with a scatt...

    $25.00

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