• JLA Vol:6 Iss:4 (Characteristics of power meters for high power CO<sub>2</sub> lasers)

    Keng H. Leong
    Donna J. Holdridge
    Kenneth R. Sabo
    Laser Applications Laboratory, Technology Development, Argonne National Laboratory, University of Chicago, IL 60439, U.S.A.

    Four different instruments used for measuring CO2 laser beam power in the kilowatt range were evaluated. The techniques used to determine the laser beam power included temperature increase from an absorber of known mass and specific heat, temperature increase from a steady flow of water used to cool the absorber, thermal gradient caused by edge&hyphen;cooling a circular absorber, and diffuse scattering from a small portion of the water&hyphen;cooled absorber surface. Th...


  • JLA Vol:6 Iss:4 (Effect of the helium&ndash;neon laser on the healing of extraction wounds: A histological study in rats)

    Walter Niccoli&hyphen;Filho
    Tetuo Okamoto

    A histological study on the healing of extraction wounds following laser irradiation using a He–Ne laser, was carried out in rats. The results suggest that this mode of treatment has a beneficial effect on initial bony wound healing. Proliferation of fibroblasts and formation of trabecular osteoid tissue were found to be more prominent within the irradiated group. The deposition of led in the newly formed bone suggests swifter ossification within the irradiated group.


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

    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...


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

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


  • JLA Vol:6 Iss:4 (Exposure to &ldquo;lessons learned&rdquo;: A tool for laser safety)

    Kenneth Barat
    Susan Elisabeth Kelly
    Lawrence Berkeley Laboratory, Environment, Health & Safety Division, University of California, Berkeley, CA 94720, U.S.A.

    This article outlines the value and steps to follow for establishing a “lessons learned program”, with specific application to a laser safety program. As a communication tool and preventive measure for laser safety issues, the program is an effective means of turning accident investigation into a proactive rather than a reactive exercise by emphasizing corrective rather than disciplinary (looking for someone to blame) actions.


  • JLA Vol:6 Iss:4 (Hazardous chemicals produced by laser materials processing)

    John M. Kokosa
    GMI Engineering & Management Institute, Flint, MI, U.S.A.

    Despite evidence to the contrary, until recently many laser operators believed, or at least stated, that the only chemical by&hyphen;products of laser processing of any consequence were water and CO2. During the last eight years, especially, several investigations have shown that hazardous materials are produced when cutting or welding nearly all substrates. In the following paper, the major chemical hazards associated with processing metals, inorganics, biomaterials, and polymers are outlined.


  • JLA Vol:6 Iss:4 (Holographic optical elements (HOEs): A serious application of holography)

    Gareth T. Williams
    Jeff Fredrick
    Physics Department, San Jose State University, San Jose, CA, U.S.A.

    Without disputing the excitement and sense of accomplishment associated with the production of display holograms, this paper suggests equal rewards from the production of holographic optical elements (HOEs). The elements described here are zone plates, diffraction gratings, interference filters and mirrors, and lenses. Ways of making each of these in an optics teaching laboratory are described, but the main emphasis will be on positive lens HOE.


  • JLA Vol:6 Iss:4 (Inexpensive photodetectors for the classroom)

    Lewis R. Smith
    Science Department, Leigh High School, San Jose, CA, U.S.A.

    Many simple concepts that we introduce in optics could lead to laboratory work if we had access to photodetectors that could give a quick voltage or current response proportional to the light intensity. The device described here is easily constructed from readily available parts at a cost of about $2.00 and can be used with any light source and any conventional voltmeter.


  • JLA Vol:6 Iss:4 (Investigation into the underwater laser welding of steel)

    G. J. Shannon
    J. Watson
    W. F. Deans
    Department of Engineering, Laser Laboratory, Kings College, University of Aberdeen, Aberdeen, U.K.

    An investigation was undertaken using a 1.2 kW carbon dioxide laser for underwater butt welding of BS 4360 43A and 50D steel, in order to assess the quality of the welds and to achieve an understanding of the laser/water/material interaction. Using a high&hyphen;speed camera, the temporal behavior of the melt pool and “plasma” dynamics surrounded by an aqueous environment were monitored. Experiments were undertaken to characterize the attenuation of the laser beam in the water as a function of various foca...


  • JLA Vol:6 Iss:4 (Laser accidents: Reviewing thirty years of incidents: what are the concerns &mdash; Old and new?)

    R. James Rockwell
    Rockwell Laser Industries, PO Box 43010, Cincinnati, OH, U.S.A.

    Overall analysis reveals that laser accidents are generally caused by one or more of the following: unanticipated eye exposure during alignment; non&hyphen;use of available eye protection; equipment malfunction causing unwanted exposure; improper methods of handling high voltages, leading to severe shock or death; lack of protection for non&hyphen;beam hazards; improper restoration of equipment following service; and incorrect eyewear selection and/or eyewear failure, leading to unwanted exposure. The statistical laser information given in this review provides a starting point for more complete ...



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