JLA Vol:6 Iss:2 (Probability and risk in laser safety)

Authors:
Peter A. Smith
Special Senses Division, Royal Air Force Institute of Aviation Medicine, Farnborough, Hampshire GU14 6SZ, U.K.

International standards for the protection of the eyes from the hazards of laser radiation define a nominal ocular hazard distance (NOHD) beyond which an individual would not be expected to suffer any adverse effects from laser radiation. The NOHD assumes deliberate viewing of the laser source over an indefinite period of time and takes no account of the probability of the observer's eye being irradiated. This approach may lead to unrealistically large hazard areas for some laser devices. An alternative method of hazard assessment without compromising ...

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...

JLA Vol:6 Iss:2 (Laser safety programs in general surgery)

Authors:
Raymond J. Lanzafame
University of Rochester and Laser Center, Rochester General Hospital, Rochester, NY, U.S.A.

General surgery represents a speciality where, while any procedure can be performed with lasers, there are no procedures for which the laser is the sine quo non. The general surgeon may perform a variety of procedures with a multitude of laser wavelengths and technologies. Laser safety in general surgery requires a multidisciplinary approach. Effective laser safety requires the oversight of the hospital's “laser usage committee” and “laser safety officer” while providing a workable framework for daily laser use in a variety of clini...

JLA Vol:6 Iss:2 (National Science Foundation undergraduate faculty enhancement workshop on advanced laboratory experiments using lasers)

Authors:
James E. Parks
Charles S. Feigerle
Robert Deserio
Joseph Wiest

A National Science Foundation undergraduate faculty enhancement workshop on advanced laboratory experiments using lasers was developed at the University of Tennessee, Knoxville, with the authors as the instructors. The workshop emphasized the development and implementation of laser‐based experiments primarily suitable for advanced undergraduate physics and chemistry laboratories. Participants gained practical, hands‐on experience in approximately 16 unique laser‐based experiments in atomic and molecular physics, physical chemistry, and biophysics. The wo...

JLA Vol:6 Iss:2 (CO₂ 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‐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...

JLA Vol:6 Iss:2 (Excimer laser processing of Ti–6Al–4V)

Authors:
J. A. Folkes
K. Shibata
Nissan Motor Co. Ltd, Materials Research Laboratory, Central Engineering Laboratories, 1, Nasushima‐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 ...

JLA Vol:6 Iss:2 (Laser cladding of Ti–6Al–4V with various carbide powders)

Authors:
J. A. Folkes
K. Shibata
Nissan Motor Co., Ltd, Material Research Laboratory, Central Engineering Laboratories, 1, Natsushima‐cho, Yokosuka 237, Japan

Laser cladding Ti–6Al–4V can be achieved with various weight percentages of different carbide powders. The microstructure and morphology of the clad layer is determined by the cladding powder composition, for a given set of laser parameters, such that 10 and 20 wt %Cr₃C₂ results in a β + TiC clad microstructure; 10 and 20 wt %WC results in an α + TiC clad microstructure (plus some original WC); and Mo₂C gives an α + &be...

JLA Vol:6 Iss:2 (Laser safety notes)

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

JLA Vol:6 Iss:2 (Laser safety standards in Europe)

Authors:
B. A. Tozer
Lasermet Ltd and City University, London, U.K.

This paper reviews the present state of the standards‐making process in Europe, explaining such arcane terms as ‘CEN’, ‘CENELEC’, ‘Euronorm’ and ‘directive’. Standards‐making bodies in Europe work to strict guidelines with regard to their relationship to member countries of the EEC and EFTA, and work closely with the international standards bodies, IEC and ISO, to minimize duplication of effort and to ensure minimum conflict with international standards. The current situation with regard to laser safety standards in Europe is reviewed, and the author specul...

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 &...