• JLA Vol:6 Iss:4 (Nd:YAG laser welding of coated sheet steel)

    M. P. Graham
    D. M. Hirak
    H. W. Kerr
    D. C. Weckman
    Department of Mechanical Engineering, University of Waterloo, Waterloo, Ontario, Canada, N2L 3G1.

    The weldability of coated sheet steels by a 2 kW Nd:YAG laser has been examined. Laser seam welds were produced in 0.75‐mm thick (23 gauge) galvanized and galvannealed sheet steels in the lap‐joint configuration. Three types of laser beam power output were used: continuous wave, sine‐wave modulated, and square‐wave modulated. The effects on weld quality of varying laser welding parameters such as welding speed, shielding gas composition, and gas flow rate were stud...


  • JLA Vol:7 Iss:1 (Development of laser finishing for non‐circular profiles)

    Ko‐Wang Liu
    Paul S. Sheng
    Department of Mechanical Engineering, University of California, Berkeley, CA 94720‐1740, U.S.A.

    A laser‐based technique for finishing of non‐circular cylindrical parts is presented. In this process, the frequency characteristics of a desired non‐circular shape is extracted from a CAD through a Fast Fourier Transform algorithm and implemented through a CO2 laser machining system. A galvanometer‐based scanner is used in the process to achieve programmable beam trajectories and high‐speed finishing. An error estimation scheme can be developed to determine the final dimensional erro...


  • JLA Vol:7 Iss:1 (Electrical hazards associated with lasers)

    Arthur G. Varanelli
    Raytheon Co., 141 Spring St., Lexington, MA 02173, U.S.A.

    The range and degree of electrical hazards associated with lasers is generally greater than encountered with other forms of equipment in the industrial, commercial, or scientific sectors. In laser equipment the electrical energy conversion to ‘optical’ wavelength energy is achieved by many methods, each method having differing electrical safety hazard exposures. Laser output is described in terms of beam power, energy, wavelength, and spatial characteristics, enabling common points of comparison and beam hazard characterization. In contrast, the methods of electrical energy conversion ha...


  • JLA Vol:7 Iss:1 (Laser chemical analysis of metallic elements in aluminum samples)

    B. Besco´s
    A. Gonza´lez Uren˜a
    Unidad de La´seres y Haces Moleculares, Instituto Pluridisciplinar, Universidad Complutense de Madrid, Juan XXIII‐1°, 28040‐Madrid, Spain

    This paper reports on the simultaneous detection of Mg, Mn, and Ti in Al samples using laser‐breakdown spectroscopy and optical multichannel analysis of photoablated microplasma. Two different experimental procedures were used depending on the emission intensity selected as reference. For those elements like Mg and Mn having emission lines close to some line of the matrix element, a direct method was used that consisted of taki...


  • JLA Vol:7 Iss:1 (Photodynamic therapy)

    Leonard I. Grossweiner
    Physics Department, Illinois Institute of Technology, Chicago, IL 60616 and Wenske Laser Center, Ravenswood Hospital Medical Center, Chicago, IL 60664, U.S.A.

    Photodynamic therapy (PDT) is a new treatment for solid tumors utilizing the combined action of light and a photosensitizing drug. Laser–fiber optic delivery systems make it practical to treat superficial and interstitial cancers, including malignancies of the skin, head and neck, esophagus, endobronchial tract, stomach, urinary bladder, female genital tract, and other sites. The putative action mechanism in PDT involves photochemical destruction of tumor tissue membranes mediated by singlet...


  • JLA Vol:7 Iss:1 (Safe laser system design for production)

    Ami Kestenbaum
    Richard J. Coyle
    Patrick P. Solan
    AT&T Bell Laboratories Engineering Research Center, Princeton, NJ 08542‐0900, U.S.A.

    The majority of industrial lasers used in manufacturing are Class IV lasers. Engineering and administrative control measures appropriate to that class of lasers must be enforced to ensure their safe use in production environments, i.e. they should be designed into Class 1 laser systems. In addition, several other design characteristics unique to industrial applications are normally incorporated into these Class I systems, such as interlocked enclosures, process mon...


  • JLA Vol:7 Iss:1 (Taking advantage of laser properties to enhance demonstrations and student laboratories)

    Michele L. Brill
    Camden County College—Physics/Lasers, Box 200, Blackwood, NJ 08012, U.S.A.

    This paper reflects the proceedings of a workshop for local educators provided by Camden County College Laser Curriculum faculty which addressed the question: ‘How can the teacher take advantage of laser properties to improve or enhance demonstrations and student labs?’ Explored here are illustrative ways in which to utilize, for educational purposes, the three well‐known characteristics of lasers: monochromaticity, directionality, and coherence. There is a faculty overlap between the Physics Department and the Laser Curriculum faculty at the college. The use o...


  • JLA Vol:7 Iss:1 (Ultrasonic vibration aided laser welding of Al alloys: improvement of laser welding‐quality)

    J. S. Kim
    T. Watanabe
    Y. Yoshida

    Using a pulsed YAG laser, meltability of Al‐Mg and Al‐Mg‐Si alloys were investigated by a single‐pass irradiation. In order to improve the quality in laser welding, the effectiveness of the Ultrasonic Vibration Laser Welding (UVLW) method proposed in this paper was investigated experimentally. The proposed method was also compared with the traditional welding methods of Normal Laser Welding (NLW) and preHeating Laser Welding (HLW). The welding methods were evaluated from the geometry in the melt zone generated by a single pulse of the laser beam. It was suggested that ultrasonic vibration ...


  • JLA Vol:7 Iss:2 (A study of polarization‐maintaining fiber characteristics with applications to force and displacement sensing)

    P. V. P. Yupapin
    K. Weir
    K. T. V. Grattan
    A. W. Palmer

    An experimental investigation of three different types of highly birefringent fiber sensor element configured as a force and a displacement sensor is described. From the coupling of power between the two eigenmodes, the magnitude of the force and the position of the coupling point can then be determined using ‘white‐light interferometric’ techniques.


  • JLA Vol:7 Iss:2 (Fiber optic equipment to supplement today's laser electro‐optic laboratories and global communication highway)

    Thomas A. Cellucci
    Newport Corporation, 1791 Deeve Ave., Irvine, CA 92714, U.S.A.

    As the key technology of the Information Superhighway, fiber optics is poised for explosive growth in the next decade. This paper identifies some of the major obstacles involved in establishing a university‐level fiber optics laboratory, and suggests time‐and money‐saving solutions with an emphasis on pre‐packaged fiber optic laboratory kits.



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