• JLA Vol:6 Iss:2 (Proposal for a standard for laser plume filter technology)


    Authors:
    Douglas E. Ott
    School of Engineering, Mercer University, Macon, Georgia, and Georgia BioMedical, Inc., Macon, Georgia, U.S.A.


    A methodology to critically appraise and assess the efficiency and efficacy of filters used in smoke evacuation systems is proposed. Currently the methods for evaluation of laser smoke evacuation systems and filtering are fraught with inconsistency, and laced with innuendo and extraopolation. A variety of tissues including beef, chicken, pork, mouse and human have been described. Both carbon dioxide and ND:YAG lasers have been used. A wide range of power densities have been applied. Environmental conditions during the studies either have not been descr...

    $25.00

  • JLA Vol:6 Iss:3 (Acoustic emission response of soda lime glass after a single Nd‐YAG laser pulse)


    Authors:
    R. Harrysson
    P. Vomacka
    Department of Engineering Materials, Luleå University of Technology, S‐951 87 Luleå, Sweden


    When machining brittle solids with a laser, crack formation can occur in the material around the irradiated area causing a strength reduction of the machined material. The purpose of this work was to study a well known brittle material (soda lime glass) by means of acoustic emission (AE) in order to investigate the correlation between visually observed crack formation and detected AE energy released by the crack formation in the material. During and after irradiation of soda lime glass with an Nd‐YAG laser pulse, the number...

    $25.00

  • JLA Vol:6 Iss:3 (Attenuation of laser radiation by particles during laser materials processing)


    Authors:
    F. Hansen
    W. W. Duley
    Guelph‐Waterloo Centre for Graduate Work in Physics, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1


    The extinction, absorption and scattering of laser radiation by small aerosol particles of Fe, Fe3O4, Al, and Al2O3 have been calculated using Mie theory at wavelengths of 1.06 and 10.6 μm. It is shown that the attenuation of incident laser radiation by particles with radii r in the range 10 nm ⩽ r ⩽ 10 μm can be significant over pathlengths as small as 10−2 m when the ratio of aerosol mass density to solid density, M/ρ &...

    $25.00

  • JLA Vol:6 Iss:3 (Characterization of metal surfaces irradiated by a long‐pulse KrF excimer laser)


    Authors:
    Th. Sarnet
    J. E. Montagne
    G. Inglesakis
    M. Autric
    L. Barrallier
    G. Barreau



    Metallic samples were irradiated by a long&hyphen;pulse (τ > 300 ns) KrF laser. The experiments were performed with an energy density of 0.3–120 J cm−2 and a power density of 1–400 MW cm−2. The samples investigated were pure aluminum, aluminum alloy, low&hyphen;alloy constructional steel and titanium alloy. They were polished to obtain a roughness of 10 < Ra < 0.08 μm and stress&hyphen;relief heat&hyphen;treated for some residual stress measurements. The characterization of th...

    $25.00

  • JLA Vol:6 Iss:3 (Fast manipulation and modulation of laser beams with spinning devices)


    Authors:
    Gareth T. Williams
    Physics Department, San Jose State University, San Jose, CA, U.S.A.


    Inexpensive battery&hyphen;operated motors can be used for a variety of safe, fast, laser beam&hyphen;steering and modulation activities, a number of which have been developed as part of the Laser Applications in Science Education (LASE) Project at San Jose State University. Those described here will be a laser stroboscope using a spinning slotted disc; a circular scanning system using a tilted rotating mirror, for bar&hyphen;code reading, investigating the focusing properties of lenses, lens aberrations and beam profiles; and a rotating polarizing sheet.

    $25.00

  • JLA Vol:6 Iss:3 (Free electron laser irradiation at 200 &mu;m inhibits DNA synthesis in living cells)


    Authors:
    Michael W. Berns
    William Bewley
    Chung&hyphen;Ho Sun
    Pamela Templin
    Alexander Karn



    The effect of a 200 μm wavelength free electron laser (FEL) beam on vertebrate tissue culture cells in two study series is described. Cell cultures exhibited no morphological alterations. However, a statistically significant proportion of the cells exhibited a reduction in tritiated thymidine incorporation. The results suggest that this wavelength might affect DNA synthesis, and the studies demonstrate the feasibility of biological investigations with the FEL.

    $25.00

  • JLA Vol:6 Iss:3 (High&hyphen;energy, long&hyphen;pulse, electron&hyphen;beam driven KrF laser in laser&ndash;matter interaction)


    Authors:
    J&hyphen;E. Montagne
    Th. Sarnet
    G. Inglesakis
    M. Autric
    Institute of Fluid Mechanics — Laser–Matter Interaction Group, Marseilles, France


    A high&hyphen;energy, long&hyphen;pulse, large&hyphen;volume, electron&hyphen;beam driven KrF laser was constructed in order to carry out laser–matter interaction experiments with metals, ceramics and polymers in the ultraviolet spectral range at 248 nm. This laser delivers up to 200 J in 400 ns. In the framework of applications such as machining or shock&hyphen;hardening, the knowledge of mechanical phenomena is very important in order to understand and maximize laser parameters. An ...

    $25.00

  • JLA Vol:6 Iss:3 (Laser express: Putting together a laser&hyphen;based road show)


    Authors:
    Steven S. Lympany
    Laser & Electro&hyphen;Optics Technology, Central Carolina Community College, Lillington, NC 27546, U.S.A.


    Laser technology has progressed to the point that most elementary through high school students are familiar with one or more laser applications. However, many of these students have not had the opportunity to witness a laser in acton where they can touch it and see it directly. In addition, most students are unaware of the career possibilities the field of laser technology has to offer. This paper presents the specifics of a successful laser&hyphen;based program that has been offered to K&hyphen;12 students and teachers in North Carolina over the la...

    $25.00

  • JLA Vol:6 Iss:3 (Low&hyphen;level laser therapy (LLLT) and safety considerations)


    Authors:
    Myron L. Wolbarsht
    Psychology Department, Duke University, Durham, NC 27706, U.S.A.


    Although the low&hyphen;power HeNe lasers and diode lasers used for low&hyphen;level laser therapy (LLLT) and photoactivation of biological processes are usually thought to be “safe”, the possibility that such lasers can cause biological effects raises the question of whether such laser action may, under some conditions, be adverse and thus be unsafe. Some research data can be interpreted as evidence for adverse effects. Laser safety standards classify all CW HeNe lasers with an output power below 1 mW as “Class 2,” as they are not considered a realistic hazard, whereas...

    $25.00

  • JLA Vol:6 Iss:3 (Safety concerns about laser pointers)


    Authors:
    David H. Sliney
    Jerome E. Dennis



    In the past two years considerable concerns have been expressed about the safety of Class 3A laser pointers. The concern has been that Class 3A diode–laser pointers have replaced the safer helium–neon (He–Ne) Class 2 laser pointers. Hundreds of thousands of small He–Ne visible&hyphen;wavelength lasers have been traditionally used for alignment and pointing, laser demonstrations and laser displays in science, education and industry, but can the diode laser be as safe and effective? Not infrequently, some people associate “lasers” with Buck Rogers and “Star Wars”, and are concerned wh...

    $25.00

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