JLA Vol:25 Iss:1 (Review on laser drilling I. Fundamentals, modeling, and simulation)

Authors:
Wolfgang Schulz
Fraunhofer Institute for Laser Technology, ILT, Aachen, Germany and Nonlinear Dynamics of Laser Processing, RWTH Aachen University, 52074 Germany

Urs Eppelt
Nonlinear Dynamics of Laser Processing, RWTH Aachen University, 52074 Germany

Reinhart Poprawe
Fraunhofer Institute for Laser Technology, ILT, Aachen, Germany and Nonlinear Dynamics of Laser Processing, RWTH Aachen University, 52074 Germany

High peak power lasers have been used for years for ablating matter. The most relevant application of this process is laser marking. Marking meets the demands of applications although the quality of ablation has potential to b...

JLA Vol:25 Iss:1 (Investigation on multi-track multi-layer epitaxial growth of columnar crystal in direct laser forming)

Authors:
XuanTuoi Do
State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, No. 28, Xianning West Road, Xi'an 710049, China and Le Quy Don University, No. 100, Hoang Quoc Viet Street, Hanoi 7EN-218, Vietnam

Dichen Li
Anfeng Zhang
Bin He
Haiyang Zhang
State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, No. 28, Xianning West Road, Xi'an 710049, China

Tatkhoa Doan
State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, No. 28, Xianning West Road, Xi'an 710049, China and Le Quy Don Technical Univers...

JLA Vol:25 Iss:3 (Surface tension stabilized laser welding (donut laser welding)—A new laser welding technique)

Authors:
Peter Haglund
Department of Engineering Sciences and Mathematics, Luleå University of Technology and Westinghouse Electric Sweden AB, SE-721 63 Va¨sterås, Sweden

Ingemar Eriksson
John Powell
Alexander Kaplan
Department of Engineering Sciences and Mathematics, Luleå University of Technology

A new laser welding process is presented which delivers a porosity free, spatter free weld. The process involves a donut shaped melt with a central hole of the same order of magnitude as the material thickness. The laser illuminates only the leading section of this melt. The hole is kept open by the melt surface tension.

JLA Vol:25 Iss:3 (The influence of position in overlap joints of Mg and Al alloys on microstructure and hardness of laser welds)

Authors:
S. Bannour
Unite´ de Thermique et Thermodynamique des Proce´de´s Industriels, Ecole Nationale d'Inge´nieurs de Monastir, Avenue Ibn Jazzar, 5019 Monastir, Tunisia and Institut de Me´canique de Marseille, Laboratoire IUSTI, UMR CNRS 6595, Universite´ de la Me´diterrane´e—Aix-Marseille Universite´, Technopoˆle de Chaˆteau- Gombert, 60 rue Joliot Curie, 13453 Marseille Cedex 13, France

K. Abderrazak
Unite´ de Thermique et Thermodynamique des Proce´de´s Industriels, Ecole Nationale d'Inge´nieurs de Monastir, Avenue Ibn Jazzar, 5019 Monastir, Tunisia

S. Mattei

JLA Vol:25 Iss:3 (Analysis of nanosecond laser ablation of aluminum with and without phase explosion in air and water)

Authors:
Yunfeng Cao
Xin Zhao
Yung C. Shin
Center for Laser-based Manufacturing, Purdue University, West Lafayette, Indiana 47907

Despite extensive research work, accurate prediction of the ablation behavior in the high energy nanosecond laser ablation process is still lacking, which may differ significantly depending on laser parameters, surrounding medium, and target material characteristics. In this paper, nanosecond laser ablation of aluminum in air and water is investigated through a self-contained hydrodynamic model under different laser fluences involving no phase explosion and phase explosion. The ablation depths and profiles are predicted and validat...

JLA Vol:25 Iss:3 (Laser direct joining of carbon fiber reinforced plastic to aluminum alloy)

Authors:
Kwang-Woon Jung
Yousuke Kawahito
Makoto Takahashi
Seiji Katayama
Joining and Welding Research Institute (JWRI), Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan

Laser direct joining of carbon fiber reinforced plastic (CFRP) to aluminum alloy was performed using a high quality continuous wave diode laser with a line-shaped beam. The tensile shear test results demonstrated that a strong lap joint with about 3000 N could be produced between CFRP (of 3 mm thickness and 20 mm width) and aluminum alloy (of 2 mm thickness and 30 mm width). The joints fractured along the joint interface or in the melted zone of CFRP. It was obser...

JLA Vol:25 Iss:3 (Surface pore initiated fatigue failure in laser clad components)

Authors:
M. M. Alam
J. Powell
A. F. H. Kaplan
Department of Engineering Science and Mathematics, Luleå University of Technology, SE-971 87 Luleå, Sweden

J. Tuominen
P. Vuoristo
Department of Materials Science, Tampere University of Technology, FI-33101 Tampere, Finland

J. Miettinen
J. Poutala
Department of Mechanics and Design, Tampere University of Technology, FI-33101 Tampere, Finland

J. Na¨kki
Department of Materials Science, Tampere University of Technology, FI-33101 Tampere, Finland and Technology Centre KETEK Ltd, FI-67100 Kokkola, Finland

J. Junkala

JLA Vol:25 Iss:3 (Evaluation of corneal and eye lens irradiance for optical aided viewing)

Authors:
Enrico Galbiati
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:25 Iss:3 (Laser-assisted plasma arc welding of stainless steel)

Authors:
Achim Mahrle
Institut fu¨r Fertigungstechnik IF, Technische Universita¨t Dresden, 01062 Dresden, Germany and Fraunhofer IWS Dresden, Winterbergstrasse 28, 01277 Dresden, Germany

Sascha Rose
Michael Schnick
Institut fu¨r Fertigungstechnik IF, Technische Universita¨t Dresden, 01062 Dresden, Germany

Eckhard Beyer
Institut fu¨r Fertigungstechnik IF, Technische Universita¨t Dresden, 01062 Dresden, Germany and Fraunhofer IWS Dresden, Winterbergstrasse 28, 01277 Dresden, Germany

Uwe Fu¨ssel
Institut fu¨r Fertigungstechnik IF, Technische Universita¨t Dresden, 01062 Dresden, Germany

JLA Vol:25 Iss:3 (Random testing reveals excessive power in commercial laser pointers)

Authors:
Joshua Hadler
Quantum Electronics and Photonics Division, NIST, Boulder, Colorado 80305

Edna Tobares
Office of Safety, Health and Environment, NIST, Gaithersburg, Maryland 20899

Marla Dowell
Quantum Electronics and Photonics Division, NIST, Boulder, Colorado 80305

In random testing of 122 commercial laser pointers, the authors observed that 90% of green pointers and 44% of red pointers were not in compliance with the Code of Federal Regulations (CFR), producing laser power in excess of the CFR-allowed limit at one or more laser wavelengths. The measurement results are presented and the authors describe the inexpensive test bed they ...