JLA Vol:4 Iss:3 (In the Canadian World: No Second Chances)

Authors:
Jeff Elie

JLA Vol:4 Iss:3 (Probing Plume Protection Problems in the Health Care Environment)

Authors:
John M. Kokosa
Marcus D. Benedetto
GMI Engineering & Management Institute, Flint, MI 48504, Ophthalmic Research, P.O. Box 560933, Orlando, FL 32856

This paper presents pragmatic particulars pertaining to plume protection problems with special emphasis on the health care environment. Practical approaches to optimizing protection are discussed with an eye toward facilitating the safety of personnel and the general health care environment from particulates, parasites, viruses and other undesirable entities, elements and compounds.

JLA Vol:5 Iss:2 (Laser Light Scattering in Biomedical Diagnostics and Therapy)

Authors:
Valery V. Tuchin
Chernyshevsky Saratov State University, Astrakhanskaya 83, 410071 Saratov, Russia

The description of special features of laser light interaction with biotissues, such as the skin, eye and dental tissues etc., with respect to laser diagnostics and therapy methods development is done. Optical models of transparent and turbid biotissues are analyzed. The role of static and dynamic light scattering in the light dosimetry, tissue heating, and receiving information of biotissue optical parameters, its structure, movements, and vibrations is considered.

JLA Vol:5 Iss:1 (Prediction Of Cavity Shape And Material Removal Rates Using A Two Dimensional Axisymmetric Heat Conduction Model For Fibrous Ceramic Insulation And Comparison With Experiments)

Authors:
Mingli He
P. J. Bishop
A. Minardi
University of Central Florida

High power lasers are used in industry as machining tools for many operations including drilling, cutting, welding, and etching. Because of its advantages over conventional machining such as tight tolerances, ability to machine hard materials without wearing of the machine tool, and ease of automation, an experimental and analytical study was undertaken to investigate the feasibility of the laser to cut a nearly pure fibrous ceramic used as insulation material on the Space Shuttle. An analytical model was developed for drilling using a spatially varying laser beam. The model was used to ...

JLA Vol:5 Iss:1 (LASER CUTTING OF STEELS: A physical and chemical analysis of the particles ejected during cutting. Part II)

Authors:
J. Powell
A. Ivarson
C. Magnusson

This paper is a continuation of work published in an earlier edition of this journal[1]. Both papers deal with the results of a detailed analysis of the particles ejected from the cut zone during laser cutting of mild and stainless steels. Reference 1 presented the thermochemical data and discussion generated by the experimental investigation. This paper concentrates on the physical characteristics and metallography of the particles. Analysis techniques used included: Scanning Electron Microscopy, optical microscopy, metallography and particle sizing. The results from this extensive analysis have enabled the authors...

JLA Vol:5 Iss:1 (Heat Flow in Laser Die Blank Welding)

Authors:
Y.‐S. Yang
C. R. Hsu
C. E. Albright
Y. Kuroda

Laser welded die blanks are finding increased usage in many industrial applications. This investigation was undertaken to establish a simplified means of calculating thermal cycles experienced in the fusion and heat affected zones on laser welds typically used in die blank welding. A planar solution domain perpendicular to the direction of travel was selected to simplify the finite element calculations. The resulting calculation technique provided reasonably accurate prediction of the thermal cycles measured by Moon and Metzbower, and the size of fusion zones and heat affected zones o...

JLA Vol:5 Iss:1 (Single Pass Laser Cutting of Polymers)

Authors:
R. Patel
G. Baisch
IBM Corporation, GTD, Hopewell Junction, New York

Since the early 1980's discovery of the ability of excimer lasers to etch polymers precisely and cleanly with minimal thermal damage, excimer lasers have been used actively in the semiconductor industry for various manufacturing processes. In the present study a process for laser cutting of polymers has been investigated. A laser beam of controlled cross‐sectional shape is imaged onto a polymer surface. The geometry of the cutting path is controlled by precise movement of a sample mounted on a 2‐axis computer controlled work stage. This type of a process is useful for applications ...

JLA Vol:5 Iss:2 (Some Military Conversion Projects for Biomedical Applications)

Authors:
James H. Kerr
Leon Goldman
Departments of Dermatology and Clinical Investigation, Naval Hospital, San Diego, California

JLA Vol:5 Iss:2 (Experimental Method for Determining the Coherence Length of CW Lasers Using a Michelson Interferometer)

Authors:
Sami Alaruri
Allison Gas Turbine Division, General Motors Corporation, Sensor Development Group

Theoretical analysis of the relationship between coherence length and the resonant‐longitudinal modes in an optical cavity is given. A Michelson interferometer is used to measure the coherence lengths of two CW He‐Ne laser cavities. Analysis of the experimental measurements shows good agreement with the theoretically predicted values.

JLA Vol:5 Iss:2 (Real‐Time Fast Fourier Transform Analysis of Acoustic Emission during CO₂ Laser Welding of Materials)

Authors:
Y‐L. Mao
G. Kinsman
W. W. Duley
Physics Department, University of Waterloo, Waterloo, Ontario, Canada, N2L 3G1

Real‐time fast Fourier transform (FFT) analysis of acoustic emission has been developed for monitoring laser welding processes. Significant differences in acoustic emission have been observed in conduction and keyhole processing regimes. The amplitude fluctuation of acoustic emission becomes intensified in the transition from conduction welding to keyhole welding. The integrated FFT power spectrum emission has been correlated to laser power, welding speed, and focusing parameters. These results suggest a simple way of monitori...