JLA Vol:6 Iss:4 (Exposure to “lessons learned”: A tool for laser safety)
Authors:
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.
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JLA Vol:6 Iss:4 (Hazardous chemicals produced by laser materials processing)
Authors:
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‐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.
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JLA Vol:6 Iss:4 (Holographic optical elements (HOEs): A serious application of holography)
Authors:
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.
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JLA Vol:6 Iss:4 (Inexpensive photodetectors for the classroom)
Authors:
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.
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JLA Vol:6 Iss:4 (Investigation into the underwater laser welding of steel)
Authors:
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‐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...
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JLA Vol:6 Iss:4 (Laser accidents: Reviewing thirty years of incidents: what are the concerns — Old and new?)
Authors:
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‐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‐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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JLA Vol:6 Iss:4 (Nd:YAG laser welding of coated sheet steel)
Authors:
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...
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JLA Vol:7 Iss:1 (Development of laser finishing for non‐circular profiles)
Authors:
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...
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JLA Vol:7 Iss:1 (Electrical hazards associated with lasers)
Authors:
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...
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JLA Vol:7 Iss:1 (Laser chemical analysis of metallic elements in aluminum samples)
Authors:
B. Besco´s
A. Gonza´lez Uren˜a
Unidad de La´seres y Haces Moleculares, Instituto Pluridisciplinar, Universidad Complutense de Madrid, JuanXXIII ‐1°, 28040‐Madrid, SpainThis 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...
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