JLA Vol:1 Iss:3 (Laser Welding of Plastics in Low and High Gravity Environments)

Authors:
R. E. Mueller
W. W. Duley
CRESS and Laser Processing Laboratory, York University, Toronto, Ontario, Canada M3J 1P3

S. MacLean
M. Garneau
B. Tryggvason
Canadian Astronaut Office, National Research Council, Ottawa, Ontario, Canada K1A 0R6

W. F. J. Evans
Atmospheric Environment Service, 4905 Dufferin Street, Downsview, Ontario M3H 5T4

Initial results of a series of laser processing experiments performed under the micro‐gravity conditions supplied by NASA's KC‐135 aircraft are presented. Weld morphologies of polypropylene and polyethylene were obtained under both hyper‐ and hy...

JLA Vol:14 Iss:4 (Determining source size from diode laser systems)

Authors:
Wesley J. Marshall
U.S. Army Center for Health Promotion and Preventive Medicine, Aberdeen Proving Ground, Maryland 21010-5403

Although hazard classification is performed at predefined distances, the maximum permissible exposure (MPE) for extended-source diode lasers decreases as the distance from the laser increases. The MPE depends on the apparent angular subtense of the source, which is simply the magnified image of the emitting diode. Small diameter beams require special consideration.

JLA Vol:9 Iss:4 (Dual wavelength laser beam alloying of aluminum alloy for enhanced corrosion resistance)

Authors:
Z. Liu
K. G. Watkins
W. M. Steen
R. Vilar
M. G. Ferreira

Aluminum alloys are known for their poor resistance to localized attack and, in particular, for pitting in chloride‐containing electrolytes. In this paper, improvement of the pitting corrosion resistance of 2014‐T6 aluminum alloy has been investigated by means of laser surface alloying of Cr into the substrate. Since aluminum is a highly reflective and thermally conductive material, it is often difficult to process with laser beams. Oxide films on the surface can prevent surface alloying as with the case of Cr alloying into aluminum by in‐situ...

JLA Vol:18 Iss:4 (Cutaneous sensation threshold for 3.8 μm radiation from a short duration pulsed laser on the calves of human subjects: A pilot study)

Authors:
Thomas E. Johnson
Michael J. Roy
Department of Environmental and Radiological Health Sciences, Colorado State University, 1618 Campus Delivery, Fort Collins, Colorado 80528 and Department of Medicine, School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, Maryland 20814

The objective of this study was to determine the threshold for sensing a 3.8 μm laser on the skin. The identification of the skin sensation threshold for invisible lasers is useful in providing scientific guidance to the safety community regarding accidental skin exposures. Knowledge of the level of sensation of lasers might be used to s...

JLA Vol:4 Iss:1 (The Impact of European Standards, Directives and the CE Mark)

Authors:
A. Roy Henderson
Bioptica, St. John's Innovation Park, Cambridge U.K.

JLA Vol:23 Iss:4 (Investigation of the effect of irradiance and pulse duration in industrial percussion laser-drilling of Waspaloy)

Authors:
Robin Bright
Harris L. Marcus
Institute of Materials Science and the Department of Chemical, Materials, and Biomolecular Engineering, University of Connecticut, Storrs, Connecticut 06269-3136

As the use of pulsed lasers in the manufacture of cooling holes in high-temperature gas-turbine engine components continues to increase, understanding the material behavior during laser-material interaction and the subsequent effects on hole quality becomes critical. In this study, atomic emission spectroscopy is used to monitor the optical characteristics of ejected material during percussion laser-drilling of Waspaloy over irradiance and pulse duration values in the ranges...

JLA Vol:17 Iss:2 (Modeling of laser deposition and repair process)

Authors:
Lijun Han
Kaushik M. Phatak
F. W. Liou
Department of Mechanical and Aerospace Engineering, University of Missouri-Rolla, Rolla, Missouri 65409-1350

Laser aided deposition is a material additive based manufacturing process via metallurgically bonding the deposited material to the substrate. Due to its capability to bond various materials together, it becomes an attractive technology for part repair in small scale. However, the details of the process remain an active area for research because of the complicated interactions involved. In this study, a mathematical model was established to investigate thermal and mass transportation phenomena, which incl...

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:21 Iss:4 (How the laser started)

Authors:
Charles Townes
Department of Physics, University of California, Berkeley, California 94720

JLA Vol:25 Iss:1 (Fatigue crack propagation in laser alloyed ductile cast iron surface)

Authors:
Zheng-yang Li
Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China and Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, People's Republic of China

Hai-yan Zhao
Yu Gu
Min-lin Zhong
Bin Zhang
Hong-jun Zhang
Wen-jin Liu
Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, People's Republic of China

Zhi-yuan Ren
Ming-jiang Yang