JLA Vol:20 Iss:3 (Diode-pumped solid state laser light sources for confocal laser scanning fluorescence microscopy)

Authors:
Mårten Stjernstro¨m
Department of Applied Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden and Department of Chemistry, Royal Institute of Technology, SE-100 44 Stockholm, Sweden

Fredrik Laurell
Hjalmar Brismar
Department of Applied Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden

Diode-pumped solid-state lasers (DPSSLs) have been integrated as light sources in confocal laser scanning microscopy (CLSM). The standard argon ion laser at 488 nm is compared with a DPSSL operating at 473 nm in terms of noise and CLSM image characteristics. The equally high fluorescence image quality togeth...

JLA Vol:25 Iss:4 (Complex analysis of elaboration of steel–TiC composites by direct metal deposition)

JLA Vol:7 Iss:1 (Safe laser system design for production)

Authors:
Ami Kestenbaum
Richard J. Coyle
Patrick P. Solan
AT&T Bell Laboratories Engineering Research Center, Princeton, NJ 08542‐0900, U.S.A.

The majority of industrial lasers used in manufacturing are Class IV lasers. Engineering and administrative control measures appropriate to that class of lasers must be enforced to ensure their safe use in production environments, i.e. they should be designed into Class 1 laser systems. In addition, several other design characteristics unique to industrial applications are normally incorporated into these Class I systems, such as interlocked enclosures, process mon...

JLA Vol:14 Iss:3 (Assessment of laser Doppler perfusion imager&rsquo;s <em>in vivo</em> reliability: Can it be used for a prospective analysis?)

Authors:
Antonella Caselli
Array

Damanpreet Singh Bedi
Colleen O’Connor
Chirag Shah
Aristidis Veves
Joslin–Beth Israel Deaconess Foot Center, Department of Surgery, and Microcirculation Laboratory, Beth Israel–Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts

The aim of this study was to assess the reliability of the laser Doppler perfusion imager (Lisca PIM 1.0; Lisca development, Linkoping, Sweden) for longitudinal analysis. We measured the skin blood flow under a biological zero condition at the forearm level in 84 patients enrolled in a 12 week prospective interventional trial. Sin...

JLA Vol:18 Iss:4 (Aluminum alloy welding by using a high power direct diode laser)

Authors:
N. Abe
M. Tsukamoto
Joining and Welding Research Institute, Osaka University, 11-1, Mihogaoka, Ibaraki, Osaka 567-0047, Japan

K. Maeda
K. Namba
Research and Development Center, Sumitomo Light Metal Industries, Ltd., 3-1-12 Chitose, Minato-ku, Nagoya 455-8670, Japan

J. Morimoto
School of Science and Engineering, Kinki University, 3-4-1, Kowakae, Higashiosaka, Osaka 577-8502, Japan

Aluminum alloys are the focus of increasing attention from the automobile industry because of their light weight, high formability, and easy recyclability. In this report, a 4 kW high power direct diode laser was used to exami...

JLA Vol:9 Iss:3 (High power laser welding in hyperbaric gas and water environments)

Authors:
G. J. Shannon
W. McNaught
W. F. Deans
J. Watson

A hyperbaric laser welding facility has been constructed and the feasibility of high power CO₂ and Nd:YAG laser welding in both high pressure gas and water environments, to simulated water depths of 500 m, has been established. From initial trials on welding through water at atmospheric pressure, it was found that the different absorption characteristics of water to 10.6 μm (CO₂ laser) and 1.06 μm (Nd:YAG laser) radiation proved crucial. The Nd:YAG laser was totally unsuitable as the beam was largely diffused in the water, whereas the CO₂ beam was rea...

JLA Vol:4 Iss:2 (A Systematic Method for the Design of a Multivariable Controller Actuating Power and Speed during a CO₂ Laser Surface Treatment)

Authors:
F. Bataille
J. M. Cerez
D. Kechemair

Temperature control systems actuating laser power and scanning velocity during laser surface hardening have already been presented. This paper exposes a systematic method for the design of a multivariable Linear Quadratic Gaussian controller adapted to this laser treatment. The preliminary identification step and the controller design are included. This corrector insures a better regulation and the generality of the method hopefully allows an easier adaptation to other laser treatments, materials or absorbing coatings.

JLA Vol:17 Iss:1 (Fracture control of unsupported ceramics during laser machining using a simultaneous prescore)

Authors:
A. E. Segall
G. Cai
R. Akarapu
A. Romasco
Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802

B. Q. Li
Department of Mechanical and Materials Engineering, Washington State University, Pullman, Washington 99164

While lasers offer many advantages when machining ceramics, costly premature fractures and related damage is the tradeoff often faced by manufacturers. This tradeoff is especially apparent for higher-speed machining of complex shapes where traditional “nail-bed” supports are not always practical. To help overcome these problems, re...

JLA Vol:21 Iss:3 (Laser welding of galvanized DP980 steel assisted by the GTAW preheating in a gap-free lap joint configuration)

Authors:
Shanglu Yang
Radovan Kovacevic
Center for Advanced Manufacturing, Southern Methodist University, Dallas, Texas, USA 75205

With the increasing need for reducing the vehicle’s weight, improving fuel efficiency and safety, as well as the corrosion resistance, more and more galvanized high-strength steels have been used in the automotive industry. However, the successful laser welding of galvanized steels in gap-free lap joint configuration is still a big challenge. The high-pressurized zinc vapor is readily developed at the interface of the two metal sheets due to the lower boiling point of zinc (around 906 °C) than the melting point of steel (over 13...

JLA Vol:23 Iss:3 (Spatter in laser welding)

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

Spatter, the ejection of melt from a weld pool, is a major problem whenever it occurs in a welding process. The ejection of droplets from the weld metal results in a weld with underfill, undercuts, craters, blowholes, or blowouts—all of which can have a detrimental effect on the mechanical properties of the weld. This paper presents a systematic description of the different types of spatter phenomena which occur during laser welding. A categorization system is proposed to facilitate the comparison and combination ...