JLA Vol:16 Iss:1 (Physics, chemistry, and laser microprocessing)

Authors:
W. W. Duley
Physics Department, University of Waterloo, Waterloo ON N2L 3G1, Ontario, Canada

This article discusses some basic concepts of laser processing when individual components have micron and submicron dimensions. Since joining and parting operations involve bond formation and bond breaking between atoms, the energy terms involved are quite similar in micro- and macroapplications. In fact, several elements of laser cutting and welding can be found in the laser-induced photochemical reactions of atoms and molecules. It is shown that there are no intrinsic wavelength limitations in laser processing of microsystems, as the scale length for processing is set by the dimensi...

JLA Vol:16 Iss:1 (Plume attenuation under high power Nd:yttritium–aluminum–garnet laser welding)

Authors:
J. Greses
Engineering Department, University of Cambridge, Cambridge, CB2 1RX United Kingdom

P. A. Hilton
TWI, Granta Park, Abington, Cambridge, CB1 6AL United Kingdom

C. Y. Barlow
Engineering Department, University of Cambridge, Cambridge, CB2 1RX United Kingdom

W. M. Steen
Laser Group, University of Liverpool, Liverpool, L69 3GH United Kingdom

During high-power continuous wave (cw) Nd:yttritium–aluminum–garnet (YAG) laser welding a vapor plume is formed containing vaporized material ejected from the keyhole. The gas used as a plume control mechanism affects the plume shape but not its temperature,...

JLA Vol:16 Iss:2 (Effects of irradiated conditions of Er:yttritium–aluminum–garnet laser on tooth vibration)

Authors:
Kazunori Takamori
Shigeru Watanabe
Department of Pediatric Dentistry, Meikai University School of Dentistry

Clinical studies that the Er:yttritium–aluminum–garnet (YAG) laser cause less pain in cutting. Unlike high-speed drilling Er:YAG laser irradiation does not cause pain by vibration, pressure, heat, or noise. We suspected that the greatest difference in characteristics between the Er:YAG laser and the high-speed drill is the amount of tooth vibration during cavity preparation. It will be simultaneously pain or discomfort during tooth cutting. Previously, the authors revealed that increased vibration speed was observed with an increase in Er:YAG la...

JLA Vol:16 Iss:2 (Foam coating on aluminum alloy with laser cladding)

Authors:
V. Ocelı´k
V. van Heeswijk
J. Th. M. De Hosson
Department of Applied Physics, Material Science Center and The Netherlands Institute for Metals Research, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands

K. Csach
Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 043 53 Košice, Slovakia

This article concentrates on the creation of a foam layer on an Al–Si substrate with laser technology. The cladding of Al–Si powder in the front of a laser track has been separated from the side injection of mixture of Al–Si/TiH₂ powder (foaming agent),...

JLA Vol:16 Iss:2 (High-power CO₂ laser design “from resonator end mirror to cutting lens focal point”)

Authors:
David Toebaert
HACO NV, Oekenestraat 120, 8800 Rumbeke, Belgium

Wybo Wagenaar
Infinite Simulation Systems BV, Lange Bunder 3, 4854 MB Bavel, Netherlands

An algorithm is derived that allows calculating all optical parameters relevant to the design of a high-power CO₂ laser, taking into account the practical needs of a flying-optics type of laser cutting machine. The novelty of the approach taken is that the resonator and the beam delivery optics are treated simultaneously, which allows for greater flexibility in design. To begin with, the often-used optical configuration of a stable resonator combined with a beam expander for collimation is mod...

JLA Vol:16 Iss:2 (In-process monitoring and feedback control during laser microspot lap welding of copper sheets)

Authors:
Yousuke Kawahito
Production Core Engineering Laboratory, Corporate Production Engineering Division, Matsushita Electric Industrial Co., Ltd., 2-7 Matsuba-cho, Kadoma, Osaka 571-8502, Japan

Seiji Katayama
Joining and Welding Research Institute (JWRI), Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan

The establishment of laser welding of copper sheets, as an electronics manufacturing process is anticipated. This study was performed with an objective of stably and consistently producing fully penetrated lap welds in two copper sheets of 0.1 mm thickness. A new procedure for in-process monitoring and feedback control was developed for microsp...

JLA Vol:16 Iss:2 (Investigation of weld cracking in Nd:yttrium–aluminum–garnet keyhole spot welding of materials used in optoelectronic packaging)

Authors:
Geoff J. Shannon
Unitek Miyachi Corporation, 1820 S. Myrtle Avenue, Monrovia, California 91017

Bernard Q. Li
Honeywell VCSEL Optical Division, Minnesota

The welding of a problematic optical device weld joint between dissimilar materials is investigated in depth. The original material combination of cold rolled steel 1010 with 6 μm of gold coating and 304 L produced consistent weld cracking. The CRS1010 material was fixed, however the other component was open to material selection. The materials tested were 304 L stainless steel, kovar, invar, and Carpenter high permeability 49 alloy. The effect of these different materials, laser pulse parameters, lev...

JLA Vol:16 Iss:2 (Laser direct writing and doping of diamond-like carbon, polycrystalline diamond, and single crystal silicon carbide)

Authors:
I. A. Salama
Laser-Aided Manufacturing, Materials and Micro-Processing Laboratory (LAMMMP), School of Optics, Center for Research and Education in Optics and Lasers (CREOL), Mechanical, Materials and Aerospace Engineering Department, University of Central Florida, Orlando, Florida 32816-2700

N. R. Quick
Applicote Associates, 894 Silverado Court, Lake Mary, Florida 32746

A. Kar
Laser-Aided Manufacturing, Materials and Micro-Processing Laboratory (LAMMMP), School of Optics, Center for Research and Education in Optics and Lasers (CREOL), Mechanical, Materials and Aerospace Engineering Department, University of Central Florida, Orlando, Florida 32816-270...

JLA Vol:16 Iss:2 (Laser short pulse heating of copper: Thermo–elasto–plastic analysis)

Authors:
A. F. M. Arif
B. S. Yilbas
ME Department, KFUPM. Dhahran, Saudi Arabia

Laser short pulse heating of metallic substrates results in excessive electron temperatures in the surface vicinity. This gives rise to nonequilibrium energy transport in the region irradiated by a laser beam. Moreover, the thermomechanical coupling effect should be incorporated into the energy transport equation as lattice site temperature increases. In the present study, laser short pulse heating of copper is considered. The electron kinetic theory approach is employed to model the nonequilibrium heating process while thermomechanical coupling is introduced in the energy transport equation t...

JLA Vol:16 Iss:2 (Quality and costs analysis of laser welded all steel sandwich panels)

Authors:
Henrikki Pantsar
Antti Salminen
Lappeenranta University of Technology, FIN 53850 Lappeenranta, Finland

Anssi Jansson
VTT Industrial Systems, FIN 53850 Lappeenranta, Finland

Veli Kujanpa¨a¨
Lappeenranta University of Technology, FIN 53850 Lappeenranta, Finland

Laser welding is a fast and flexible way to manufacture all steel sandwich panels. Economically the most feasible solution is often to weld as large panels as possible. In corrugated core all steel sandwich panel applications the effect of an air gap in welding is difficult to eliminate when welding large panels. A system for welding large panels with a las...