• JLA Vol:6 Iss:1 (Amending the CDRH performance standard for laser products)


    Authors:
    Jerome E. Dennis
    Office of Compliance and Surveillance Center for Devices and Radiological Heath, US Food and Drug Administration, Silver Springs, MD, U.S.A.


    The most recent amendments to the Federal performance standard for laser products became effective in 1985 and 1986. At this time, the Center for Devices and Radiological Health (CDRH) is making public its intention to amend the standard again and is inviting suggestions and comments. The amendments that are now under consideration are based upon advances in the sciences of photobiology and hazard evaluation. They are also intended to harmonize with developments in international standards for similar products, and to cla...

    $25.00

  • JLA Vol:6 Iss:1 (Authors’ reply to the comments of Rothberg and Halliwell)


    Authors:
    M. M. Rajadhyaksha
    W. H. Stevenson
    Applied Optics Laboratory, School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907, U.S.A.


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  • 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 ...

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  • JLA Vol:6 Iss:1 (Laser safety notes)


    Authors:
    Robert Weiner
    Weiner Associates, Manhattan Beach, California U.S.A.


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  • JLA Vol:6 Iss:1 (Laser vibrometry on solid surfaces: The effects of laser speckle)


    Authors:
    S. J. Rothberg
    N. A. Halliwell
    Department of Mechanical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU, U.K.


    This letter discusses the phase and amplitude modulation of Doppler signals generated in laser Doppler velocimetry (LDV) systems with reference to the paper entitled ‘Dynamic laser Doppler velocimetry on solid surfaces’ by Rajadhyaksha and Stevenson (Vol. 4 No. 2). In particular, transit time and velocity gradient frequency broadenings are described in terms of the speckle pattern behavior on the photodetector and this approach is reconciled with the scattering element approach adopted by Rajadhyaksha and Stevenson....

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  • JLA Vol:6 Iss:1 (Mass transport during laser welding of stainless steels and alloys used by US Navy)


    Authors:
    Anand J. Paul
    Parwaiz A. A. Khan
    Manufacturing and Materials Division, Concurrent Technologies Corporation, 1450 Scalp Avenue, Johnstown, PA 15904, U.S.A.


    Lasers, though developed only about a quarter century ago, are now being routinely used in the automotive, aerospace and other industries to produce superior quality, high‐speed autogenous welds with narrow heat‐affected zones in a number of alloys. However, they cannot at present be used to successfully weld certain important structural alloys due to a change in weld composition resulting from selective mass transport of certain alloying elements from the laser‐melted region. The loss of a...

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  • JLA Vol:6 Iss:1 (Measurement of temperature and absorptance for laser processing applications)


    Authors:
    S. Ramanathan
    M. F. Modest
    Department of Mechanical Engineering, The Pennsylvania State University, University Park, PA 16802, U.S.A.


    The use of CO2 lasers has been successfully demonstrated for several manufacturing processes such as cutting, drilling, scribing, etc., of a wide range of materials. The absorptance of a material at the laser wavelength and at the material removal temperature substantially affect the efficiency of the laser machining process. Some materials have absorption bands in the mid‐infrared and the absorptance changes drastically with temperature at the CO2 laser wavelength of 10.6 μm. Additionally, the absor...

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  • JLA Vol:6 Iss:1 (Standardization in the field of lasers in Europe—Towards common international standards)


    Authors:
    Ernst Sutter
    Physikalisch‐Technische Bundesanstalt, Bundesallee 100, D‐38116 Braunschweig, Germany


    Different standards in different European countries have given rise to technical trade barriers. The European Community made a great effort to establish a single market before the end of 1992 in which the free movement of goods is ensured. The first approach was to adopt directives setting up detailed requirements for all products. This has proved to be such a slow and difficult process that the New Approach has been adopted: the essential requirements are established by directives, whereas the technical specifications are detailed in harmonized standards....

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  • 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...

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  • JLA Vol:6 Iss:2 (Excimer laser processing of Ti&ndash;6Al&ndash;4V)


    Authors:
    J. A. Folkes
    K. Shibata
    Nissan Motor Co. Ltd, Materials Research Laboratory, Central Engineering Laboratories, 1, Nasushima&hyphen;cho, Yokosuka 237, Japan


    The effect of the excimer laser on the surface of Ti–6Al–4V is reported. Particular concentration is given to surface modification for potential materials processing applications. Results showed that: (i) there is an optimum energy for smoothing titanium; (ii) at this energy density increasing the number of pulses has some, but not a significant, effect on the smoothing process; and (iii) relatively smooth surfaces could be achieved ...

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