IBM Corporation, GTD, Hopewell Junction, New York
Since the early 1980's discovery of the ability of excimer lasers to etch polymers precisely and cleanly with minimal thermal damage, excimer lasers have been used actively in the semiconductor industry for various manufacturing processes. In the present study a process for laser cutting of polymers has been investigated. A laser beam of controlled cross‐sectional shape is imaged onto a polymer surface. The geometry of the cutting path is controlled by precise movement of a sample mounted on a 2‐axis computer controlled work stage. This type of a process is useful for applications ...
R. P. Salathe´
Advanced Photonics Laboratory, Ecole Polytechnique Fe´de´rale de Lausanne, Switzerland
H. P. Schwob
LASAG AG, Thun, Switzerland
We describe a novel procedure for highly reliable microspot welding of copper based on a calibrated on-line reflectivity measurement. This parameter is used to control the laser power slope and the weld spot diameter. Reliable welds are obtained without the need of other active control mechanisms. The new technique allows realizing welds with a diameter close to the laser beam waist and leads to a reduction in the relative ...
JLA Vol:20 Iss:4 (Tailored hybrid blank production—New joining concepts using different solders)
C. von der Haar
Laser Zentrum Hannover e.V., Hollerithallee 8, 30419 Hannover, Germany
A consistent lightweight concept necessitates the combination of different lightweight materials. Because of the significant weight reduction, multimaterial design is becoming more and more interesting for the transportation industry. Mixed material concepts are partially limited because of the insufficient deformation behavior of the joining seams. To overcome this limitation, a brazing process has been developed in which aluminium and steel can be joined, with an enhanced deformation beha...
JLA Vol:22 Iss:4 (Effect of laser and laser hybrid welding on the corrosion performance of a lean duplex stainless steel)
Elin M. Westin
Outokumpu Stainless AB, Avesta Research Center, P.O. Box 74, 774 22 Avesta, Sweden
Laser Processing Laboratory, Lappeenranta University of Technology, Tuotantokatu 2, 53850 Lappeenranta, Finland
The use of duplex stainless steel increases steadily worldwide and the fluctuations in nickel price the recent years have contributed to further growth. The lean duplex grade Outokumpu LDX 2101® (EN 1.4162, UNS S32101) has a low nickel content and is alloyed with nitrogen and manganese to give a balanced microstructure. It means that good austenite formation is obtained even when laser welding autogenously (without fille...
Fraunhofer‐Institut fu¨r Lasertechnik, Aachen, Germany
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: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)
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:25 Iss:5 (Numerical and experimental study of the effect of groove on plasma plume during high power laser welding)
Shanghai Jiao Tong University, Dongchuan Road 800, Shanghai 200240, China and Shanghai Key Laboratory of Materials Laser Processing and Modification, Shanghai 200240, China
The influence of groove on the static feature and dynamic behavior of plasma plume during high power CO2 laser welding process was studied using a hydrodynamic three-dimensional model and corresponding experiments. The temperature, composition, and velocity of plasma plume along the incident path of laser beam were computed. The static morphology of plasma plume was analyzed through both models ...
JLA Vol:9 Iss:4 (Dual wavelength laser beam alloying of aluminum alloy for enhanced corrosion resistance)
K. G. Watkins
W. M. Steen
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...
A. Roy Henderson
Bioptica, St. John's Innovation Park, Cambridge U.K.
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