JLA Vol:17 Iss:4 (Faster and damage-reduced laser cutting of thick ceramics using a simultaneous prescore approach)
A. E. Segall
The Pennsylvania State University, University Park, Pennsylvania 16802
Laser machining of structural ceramics is increasingly gaining acceptance as an alternative to traditional machining methods. However, despite the great promise of lasers for a variety of cutting and drilling procedures, premature fractures and prohibitively low cutting speeds are still among the greatest obstacles encountered, particularly when thick cross sections are involved. While many factors contribute to the fractures encountered during ...
Structural Metals Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
A slender keyhole formed by deep penetration laser welding fluctuates violently and is apt to form porosity. To reveal the keyhole depth behavior, the authors observed the keyhole images simultaneously by using a microfocus x-ray transmission imaging system and plasma plume images in deep penetration CO2 laser welding at various welding speeds. Plasma light emission was also measured by using photodiodes. The upper part of the keyhole was found to fluctuat...
GEST Labs, Via Kennedy, 20871 Vimercate, Italy
The use of a magnifying lens with a highly divergent laser beam may cause a big increase of the irradiance on the cornea and the eye lens. This study provides the analysis of several cases where the use of a lens lead to a corneal irradiance significantly higher than the naked-eye viewing. The examples analyzed in this study allow determining the factors that represent the increase of the corneal irradiance caused by the use of the lens. The results indicate that these factors of irradiance increase may be close to 100.
JLA Vol:24 Iss:2 (Laser dressing of metal bonded diamond blades for cutting of hard brittle materials)
Philipp von Witzendorff
Laser Zentrum Hannover e.V., Hollerithallee 8, 30419 Hannover, Germany
In this study, the authors investigate the laser dressing of metal bonded diamond blades by means of laser pulses with different pulse durations and wavelengths. Conventional dressing suffers from excessive blade wear, whereas laser dressing enables precise removal of the bonding metal to generate the required chip space of protruding diamond grains. The challenge for processing this composite material is to find appropriate level of ablation for the bonding metal without damaging the diamond grains thr...
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‐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...
JLA Vol:15 Iss:4 (Laser–material interaction and process sensing in underwater Nd:yttrium–aluminum–garnet laser welding)
Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
Tarasaki R&D Center, JAPEIC, Hitachinaka, Ibaraki 312-0003, Japan
Laser–material interaction and process sensing technology for local-dry underwater Nd:yttrium–aluminum–garnet laser beam welding were studied. The optical emissions induced by laser–water interaction were detected with an infrared (IR) optical sensor and observed with a charge coupled device camera. It was found that under laser irradiation, a kind of water–vapor plasma formed immediately above the ...
JLA Vol:20 Iss:1 (Practical and theoretical investigations into inert gas cutting of 304 stainless steel using a high brightness fiber laser)
Centre for Industrial Photonics, Institute for Manufacturing, Department of Engineering, University of Cambridge, Cambridge, CB2 1RX, United Kingdom
A 2.2 kW fiber laser was used in a series of inert cutting trials on stainless steels of section thicknesses in the range of 6–10 mm. Variations in the cutting performance with changing gas pressure, focal position, and nozzle diameter were investigated. Results showed the difficulties associated in cutting with high brightness lasers, specifically in obtaining full melt eject through narr...
JLA Vol:8 Iss:5 (Laser drilling of advanced materials: Effects of peak power, pulse format, and wavelength)
W. T. Lotshaw
A. L. Ortiz
P. R. Staver
C. E. Erikson
M. H. McLaughlin
T. J. Rockstroh
The quality of laser‐drilled holes is significantly influenced by the laser peak power, pulse format, and wavelength. Three advanced materials are used to demonstrate the importance of choosing the correct laser parameters for a specific material. The materials are: (1) intermetallic single crystal nickel aluminide (NiAl) alloy; (2) N5, a single crystal nickel‐based superalloy; and (3) a silicon carbide (SiC) ceramic matrix composite (CMC). The laser peak power is varied in terms of the pulse...
JLA Vol:2 Iss:1 (On Laser Vibrometry of Rotating Targets: Effects of Torsional and In‐Plane Vibration)
S. J. Rothberg
J. R. Baker
N. A. Halliwell
ISVR, University of Southampton, Highfield, Southampton S09 5NH, England
Vibration measurements on rotating surfaces are often referred to in the commercial literature as a major application of laser Doppler vibration transducers. This paper examines such use of these instruments and shows how the presence of a velocity component due to the rotation itself leads to spurious measurement dependence on both torsional vibration and motion perpendicular to the line of incidence of the laser beam. In addition, the scale of this dependence increases with both rotation speed and perpendicular distance between the l...
Environmental Health & Safety Office, University of California, Irvine, California 92697-2725
While training, engineering controls, warning signs/systems, and protective eyewear are emphasized in laser safety programs, laser-related accidents do occur in facilities without obvious deficiencies in those areas. Problems still occur because of insufficient attention to administrative safety issues directly related to human nature and behavioral factors. Common safety problems associated with behavioral factors are discussed. Personal experiences of the author, including lessons learned, are included. The issues are discussed within the context of laser safety, bu...
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