JLA Vol:5 Iss:1 (Heat Flow in Laser Die Blank Welding)

Authors:
Y.‐S. Yang
C. R. Hsu
C. E. Albright
Y. Kuroda

Laser welded die blanks are finding increased usage in many industrial applications. This investigation was undertaken to establish a simplified means of calculating thermal cycles experienced in the fusion and heat affected zones on laser welds typically used in die blank welding. A planar solution domain perpendicular to the direction of travel was selected to simplify the finite element calculations. The resulting calculation technique provided reasonably accurate prediction of the thermal cycles measured by Moon and Metzbower, and the size of fusion zones and heat affected zones o...

JLA Vol:17 Iss:3 (Laser beam analysis in direct metal deposition process)

Authors:
Huan Qi
Jyoti Mazumder
Center for Laser Aided Intelligent Manufacturing, Department of Mechanical Engineering, The University of Michigan, Ann Arbor, Michigan 48109

Larry Green
Spiricon, Inc., Logan, Utah 84341

Gary Herrit
II-VI, Inc., Saxonburg, Pennsylvania 16056

The quality of a laser beam profile and its stability play fundamental roles in laser material processing. Beam reflections may dramatically affect the beam quality under certain material processing conditions. In this study, experiments were carried out to examine the variations of the continuous wave CO₂ laser beam profile during the direct metal...

JLA Vol:21 Iss:4 (Contributions of Charles Townes’ research to nonlinear optics)

Authors:
Elsa Garmire
Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755, USA

Nonlinear optics was profoundly influenced by early work of Charles Townes and his group at Massachusetts Institute of Technology from 1961 to 1967. His foundational contribution was the realization that coherent molecular oscillations resulted from stimulated Raman scattering, leading to the introduction of stimulated Brillouin scattering. Self-trapping of light beams and self-steeping of light pulses in nonlinear materials were two other important innovations. Some applications today of these early ideas are outlined.

JLA Vol:22 Iss:4 (Erratum: “Weld strength improvement for Al alloy by using laser weaving method” [J. Laser Appl. 22(3), 116 (2010)])

Authors:
Kwang-Deok Choi
Young-Nam Ahn
Cheolhee Kim
Advanced Welding & Joining Technology Research Team, Korea Institute of Industrial Technology, 7-47 Songdo-Dong, Yeonsu-Gu, Incheon 406-840, Korea

JLA Vol:25 Iss:1 (Implementation of a novel scan localization system for wireless sensor networks)

Authors:
K. Sun
W. Huang
Sachula Meng
Y. Xiao
M. T. Wang
Z. Xiao
Inner Mongolia University, Hohhot 010021, China

A novel localization scheme called laser beam scan localization by combining grid and light (laser) with mobile localization policy for wireless sensor networks is designed. The scheme utilizes a moving location assistant (LA) with a laser beam, through which the deployed area is scanned. The LA sends identities to unknown nodes to obtain the locations of sensor nodes. High localization accuracy can be achieved without the aid of expensive hardware on the sensor nodes, as required by other localization systems...

JLA Vol:7 Iss:2 (Fraunhofer resource center for laser technology ‐ USA)

Authors:
Frank W. Kuepper
Fraunhofer Resource Center for Laser Technology, Ann Arbor, MI, U.S.A.

JLA Vol:15 Iss:4 (Welding of thick austenitic stainless steel using Nd:yttrium–aluminum–garnet laser with filler wire and hybrid process)

Authors:
Tommi Jokinen
Miikka Karhu
VTT Industrial Systems, P.O. Box 17021, FIN 53851 Lappeenranta, Finland

Veli Kujanpa¨a¨
Lappeenranta University of Technology, P.O. Box 20, FIN 53851 Lappeenranta, Finland

Autogenous laser welding has shown many advantages over traditional welding methods in numerous applications. However, there could be even more applications, but due to the power levels of present high power lasers, depth of penetration is limited. One way to overcome this limitation is to use multipass laser welding, in which a narrow gap and a filler wire are applied. By this process thick sections can be welded with a smaller heat inpu...

JLA Vol:19 Iss:4 (Experimental observation of keyhole shapes in the laser welding of aluminum blanks)

Authors:
B. J. Aalderink
Netherlands Institute for Metals Research, P.O. Box 217, 7500 AE Enschede, The Netherlands

R. G. K. M. Aarts
University of Twente, Laboratory of Mechanical Automation, P.O. Box 217, 7500 AE Enschede, The Netherlands

D. F. de Lange
Netherlands Institute for Metals Research, P.O. Box 217, 7500 AE Enschede, The Netherlands

J. Meijer
University of Twente, Laboratory of Mechanical Automation, P.O. Box 217, 7500 AE Enschede, The Netherlands

A camera-based in situ monitoring system for the Nd:yttrium–aluminum–garnet laser keyhole welding process of aluminium has been developed. The...

JLA Vol:9 Iss:4 (The application of external feedback in the laser spectroscopy of nonlinear media)

Authors:
B. V. Anikeev
D. V. Sin'ko
Department of Laser Physics, Volgograd State University, 2‐aya Prodolnay 30, Volgograd 400 062, Russia

A new spectroscopic technique to gain information on the nonlinear constants of optical materials is presented. This technique is made possible due to the point that the application of an external controlled negative feedback (CNF) circuit to an intracavity nonlinear cell results in the generation of extended boundaries of the stability for the laser beam. This effect is analyzed using a semiclassical set of equations that govern laser oscillation. Measurements are made on systems containing either an instantaneous CNF circuit o...

JLA Vol:4 Iss:1 (Combustion‐Assisted Laser Cutting of a Difficult‐to‐Machine Superalloy)

Authors:
P. A. Molian
M. Baldwin

In laser cutting, the largest single application of lasers in manufacturing, the assist gas plays an important role in affecting the cutting performance. The assist gas is usually oxygen or an inert gas. In this work a mixture of acetylene and oxygen was employed to create combustion reactions during CO₂ laser cutting that enabled an improvement in the cutting speed, and cut quality of a difficult‐to‐machine superalloy. A comparison with laser cutting of a plain carbon steel under identical conditions was also made to determine the usefulness of combustion energy. Results indicate that both cutting speed and qual...