JLA Vol:8 Iss:5 (Filtration of the fumes generated by industrial CO₂ laser cutting)

Authors:
J. Powell
H. Haferkamp
F. W. Bach
D. Seebaum
A. Hampe

This paper reviews the subject of fume filtration in the context of industrial laser cutting. Self‐cleaning or surface filtration can be used to good effect when cutting metals. The clean exhaust air from such a filter can be recycled into the workplace with an obvious saving on heating bills. Fumes generated during non‐metal cutting are a great deal more difficult to filter and recycling of the air is not possible.

JLA Vol:8 Iss:5 (Excimer laser interactions with an aluminum alloy)

Authors:
Angelos Koutsomichalis
Anastasia Kefalidou
Laboratory of Physical Metallurgy, National Technical University of Athens, Zografou Campus 15773 Athens, Greece

An AlCuMg alloy was irradiated using a KrF pulsed excimer laser. A microstructural study showed the presence of a laser treated zone having a uniform depth of approximately 20 μm. The surface layer of the laser treated aluminum alloy exhibited a wavy topography and its surface roughness was found to depend on the number of laser pulses per step. A X‐ray diffraction analysis revealed the presence of aluminum oxides and nitrides on the surface of the laser irradiated specimens. Corrosion measurements s...

JLA Vol:8 Iss:5 (William B. Mark Memorial Lecture)

Authors:
Kenneth A. Arndt
Department of Dermatology, Beth Israel Hospital, 330 Brookline Ave., Boston, MA 02215, U.S.A.

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.

JLA Vol:8 Iss:5 (Taking advantage of laser properties to enhance demonstrations and student laboratories)

Authors:
Michele L. Brill
Camden County College — Physics/Lasers, Box 200, Blackwood, NJ 08012, U.S.A.

This paper reflects the proceedings of a workshop for local educators provided by Camden County College Laser Curriculum faculty which addressed the question: ‘How can the teacher take advantage of laser properties to improve or enhance demonstrations and student labs?’ Explored here are illustrative ways in which to utilize, for educational purposes, the three well‐known characteristics of lasers: directionality, monochromaticity, and coherence. There is a faculty overlap between the Physics Department and the Laser Curriculum faculty at the college. The use...

JLA Vol:8 Iss:6 (The Influence of laser cavity gaseous impurities on the performance of an industrial CO₂ laser)

Authors:
C. R. Hsu
C. E. Albright
A. Khakhalev
Welding Engineering, The Ohio State University

Contamination in the cavities of high power industrial CO₂ lasers is a cause of laser performance degradation. Such degradation can result in laser downtime and significant loss of productivity. The laser cavity gas supply can contribute to this contamination, but there is confusion about the level of gas impurity concentration which can cause a degradation process. The overall objective of this investigation was to study the effects of cavity gas contaminants on the performance of an industrial fast‐axial‐flow CO₂ laser. A 3 kW fa...

JLA Vol:8 Iss:6 (Welding of aluminum: A challenging opportunity for laser technology)

Authors:
Friedrich Dausinger
Ju¨rgen Rapp
Markus Beck
Frank Faisst
Ru¨diger Hack
Helmut Hu¨gel
Universita¨t Stuttgart, Institut fu¨r Strahlwerkzeuge (IFSW), Pfaffenwaldring 43, D‐70569 Stuttgart, Germany

The increasing demand for lightweight structures has led to a greater industrial use of aluminum alloys. The application of these materials is handicapped by a lack of productivity and reliability in the joining techniques currently available. The laser welding of aluminum is markedly more difficult than for steel. The difficulties to be solved include the threshold for deep penetration welding...

JLA Vol:8 Iss:6 (A modeling study on the influence of pulse shaping on keyhole laser welding)

Authors:
P. S. Mohanty
A. Kar
J. Mazumder

A theoretical analysis describing the effects of pulse shaping on keyhole laser welding is presented. Calculation of the keyhole profile and melt pool dimensions was performed by the balancing of surface forces and energy at the liquid‐vapor and solid‐liquid interfaces in three dimensions. The effect of temporal pulse shape on weld dimensions has been examined over a range of power densities, pulse times and pulse frequencies. Several pulse types (e.g., top‐hat, Gaussian, ramp‐up and ramp‐down pulses) have been considered. Pulse shaping showed significant effect on the weld dimensio...

JLA Vol:8 Iss:6 (Laser surface alloying of magnesium base alloys)

Authors:
R. Galun
A. Weisheit
B. L. Mordike
Institut fu¨r Werkstoffkunde und Werkstofftechnik, Technische Universita¨t Clausthal, Agricolastraße 6, D‐38678 Clausthal‐Zellerfeld, Germany

The feasibility of the laser surface alloying of magnesium base alloys with aluminum, copper, nickel and silicon has been shown in this work. By laser alloying with these elements, using a 5 kW CO₂‐laser, the hardness of several magnesium base alloys can be increased to values above 250 HV_0.1. Melted depths from 700–1200 μm and alloying contents from 15–55 at % were achieved. The wear resistance of ...

JLA Vol:8 Iss:6 (Understanding high‐power fiber‐optic laser beam delivery)

Authors:
Boyd V. Hunter
Keng H. Leong
Carl B. Miller
James F. Golden
Robert D. Glesias
Patrick J. Laverty

Fiber‐optic beam delivery is commonly used in industrial laser systems. This article examines the conditions for the optimal propagation of high power beams through optical fibers. Beam quality effects by step and gradient index fibers of different lengths are considered. The differences between the diverging beam from a fiber and the beam at focus and on the fiber face are illustrated. Estimates are provided of the worst‐case beam quality to be expected from fibers. Guidelines are also provided for th...