JLA Vol:3 Iss:2 (Precision Limits of the Estimation of the Parameters of Fo¨rster Models of Fluorescence Waveforms)

Authors:
L. Jonathan Dowell
Los Alamos National Laboratory, Los Alamos, NM 87545

The author examined the precision of maximum‐likelihood‐derived, nonlinear least‐squared‐error algorithms that are suitable for laboratory implementation and that estimate the parameters of Fo¨rster models of fluorescence. The estimation precision for these parameters is limited by inherent noise in the fluorescence‐waveform measurement. This paper examines the Fo¨rster model and its recent applications and discusses parameter estimations for models of energy transfer by different wavefunction interactions. It presents the results of Monte Carlo simulation studi...

JLA Vol:26 Iss:1 (Two-dimensional simulation of laser ablation with 235 nanosecond pulses)

Authors:
Sousan Ghalamdaran
Iranian National Centre for Laser Science and Technology (INLC), PO Box 14665-576 Tehran, Iran and Department of Physics, Amir Kabir University of Technology, PO Box 15875-4413 Tehran, Iran

Parviz Parvin
Department of Physics, Amir Kabir University of Technology, PO Box 15875-4413 Tehran, Iran

Mohamad Javad Torkamany
Jamshid Sabbagh Zadeh
Iranian National Centre for Laser Science and Technology (INLC), PO Box 14665-576 Tehran, Iran

A two-dimensional thermal model of nanosecond pulsed laser ablation is developed to describe the physical processes, the plasma absorption, the crater profile, and the temp...

JLA Vol:17 Iss:4 (Developments towards controlled three-dimensional laser forming of continuous surfaces)

Authors:
S. P. Edwardson
E. Abed
P. French
G. Dearden
K. G. Watkins
Laser Group, Department of Engineering, The University of Liverpool, Liverpool L69 3GH, United Kingdom

R. McBride
D. P. Hand
J. D. C. Jones
A. J. Moore
School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom

There has been a considerable amount of work carried out on two-dimensional laser forming, using multipass straight line scan strategies to produce a reasonably controlled bend angle in a number of materials, including aerospace alloys. However, in order t...

JLA Vol:22 Iss:2 (Nd:YAG laser welding of titanium alloys using a directed gas jet)

Authors:
Jonathan Blackburn
Laser Processing Research Centre, The University of Manchester, Manchester M60 1QD, United Kingdom

Chris Allen
Paul Hilton
TWI Ltd., Granta Park, Abington, Cambridge CB21 6AL, United Kingdom

Lin Li
Laser Processing Research Centre, The University of Manchester, Manchester M60 1QD, United Kingdom

The increasing utilization of titanium alloys in the aerospace industry, a direct result of socioeconomic pressures, has created the need for a production process which can produce high quality near-net-shape titanium alloy components. Keyhole laser welding is a joining technology which could be utilized for t...

JLA Vol:24 Iss:2 (Temperature measurement of laser heated metals in highly oxidizing environment using 2D single-band and spectral pyrometry)

Authors:
Maryse Muller
Remy Fabbro
PIMM Laboratory (Arts et Me´tiers ParisTech—CNRS), 151 Bd.de l’Hoˆpital, 75013 Paris, France

Hazem El-Rabii
Institut Prime, CNRS-ENSMA-Universite´ de Poitiers, 1 Ave. Cle´ment Ader, BP 40109, 86961 Futuroscope Chasseneuil Cedex, France

Koji Hirano
Nippon Steel Corporation, Marunouchi Park Building, 2-6-1 Marunouchi, Chiyoda Ward, Tokyo 100-8071, Japan

Calibration and validation of two temperature measurement techniques both using optical pyrometry, usable in the framework of the study of the heated metals in highly oxidizing environments and more generally dur...

JLA Vol:6 Iss:3 (Laser express: Putting together a laser‐based road show)

Authors:
Steven S. Lympany
Laser & Electro‐Optics Technology, Central Carolina Community College, Lillington, NC 27546, U.S.A.

Laser technology has progressed to the point that most elementary through high school students are familiar with one or more laser applications. However, many of these students have not had the opportunity to witness a laser in acton where they can touch it and see it directly. In addition, most students are unaware of the career possibilities the field of laser technology has to offer. This paper presents the specifics of a successful laser‐based program that has been offered to K‐12 students and teachers in North Carolina over the la...

JLA Vol:1 Iss:2 (Laser Applications in Biomedicine. Part II: Clinical Applications)

Authors:
J. Stuart Nelson
Michael W. Berns
Beckman Laser Institute and Medical Clinic, University of California, Irvine, 1002 Health Sciences Road East, Irvine, California 92715

JLA Vol:16 Iss:1 (Influence of surface preparation and process parameters on the porosity generation in aluminum alloys)

Authors:
A. Haboudou
P. Peyre
CLFA, avenue Prieur de la Côte d’or, 94114 Arcueil, France

A. B. Vannes
Ecole Centrale de Lyon, Ecully, France

The 4 kW cw Nd:yttrium–aluminum–garnet laser welding of solid solution hardened A5083 (5% Mg) and precipitation-hardened A356 (7% Si) alloys, sensitive to porosity formation was carried out at different welding speeds, under He gas shielding, and for partial penetration conditions, on bead on plate configuration. The porosity formation was examined through observation and evaluation of weld beads, based on x-ray radiography inspection coupled with image analysis, and quantification of gas...

JLA Vol:20 Iss:2 (Design and validation of a hybrid laser/water-jet machining system for brittle materials)

Authors:
Dinesh Kalyanasundaram
Gamal Shehata
Clayton Neumann
Pranav Shrotriya
Pal Molian
Department of Mechanical Engineering, Laboratory for Lasers, MEMS and Nanotechnology, Iowa State University, Ames, Iowa 50011-2161

A unique laser/water-jet (LWJ) cutting head has been designed, built, and interfaced with a CO₂ laser for cutting and scribing of hard and brittle ceramic materials. Alumina samples were used to validate the effectiveness of the LWJ cutting head in thermal fracture mode. The results were compared with vaporization mode (focused beam) as well as thermal fracture mode (defocused beam) of air-assisted laser c...

JLA Vol:8 Iss:5 (A guide to developing a laser standard operating procedure)

Authors:
Ken Barat
Lawrence Berkeley National Laboratory, Berkeley, CA 94720, U.S.A.

The ANSI Z 136.1 standard requires a standard operating procedure (SOP), however, it does not recommend or suggest a format for the SOP. The goal of this article is to outline, explain and suggest an SOP format that could be applied by a laser safety officer to a varied number of situations and laser uses.