JLA Vol:1 Iss:1 (Resonant ATR (Attenuated Total Reflectance) Spectroscopy and Semiconductor Technology)

Authors:
Bruno Bosacchi
AT&T Bell Laboratories ‐ Engineering Research Center, Princeton, New Jersey

We review the resonant ATR spectroscopy as an effective way to enhance the sensitivity of the optical measurements in semiconductor technology. After a short introduction of the basic principles, we consider its application to the non‐destructive characterization of the multilayer structures used in the manufacture of electronics and optoelectronics devices (Resonant ATR technique).

JLA Vol:1 Iss:2 (A Study in Surface Alloying of Titanium Alloys)

Authors:
A. Bharti
R. Sivakumar
Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad‐500 258, India

D. B. Goel
Department of Metallurgical Engineering, University of Roorkee, Roorkee‐247 667, India

A 5 KW CW CO₂ laser has been used to alloy the surface of Ti6Al4V alloy with carbon. As a result the average microhardness was increased from 365 to 600 kg/mm.² Compositional inhomogeneity was observed on the alloyed surface, however the compositional inhomogeneity index reduced considerably by cross scanning with defocused laser beam. Surface roughness of the alloyed surface was also studied and the roughn...

JLA Vol:1 Iss:2 (High Performance Laser Triangulation Ranging)

Authors:
C. Murray Penney
GE Corporate Research and Development, Schenectady, New York 12301

Brad Thomas
Johnson Laboratories, 383 Hillen Road, Towson, Maryland 21204

Laser triangulation ranging can provide data rates to at least 10,000 points per second, with resolution on the order of one thousandth of an inch, while observing strongly uncooperative targets through hostile environments. Data rate has been increased to greater than 100,000 points per second for applications requiring high resolution 3‐D maps of extended uncooperative surfaces. One successful approach to these applications is described. Also, several optical and engineering characteristic...

JLA Vol:1 Iss:2 (ICALEO Holds First Conference on Lasers in Dentistry)

Authors:
Harvey Wigdor
Chief of Dental Service, Ravenswood Hospital Medical Center and Wenske Laser Center, Chicago, Illinois

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:1 Iss:2 (Measurement of Concentration of DHE in Tissue)

Authors:
A. Edward Profio
T. F. Khoury
Department of Chemical and Nuclear Engineering, University of California, Santa Barbara, Santa Barbara, CA 93106 U.S.A.

Stephen Lam
School of Medicine, University of British Columbia, Vancouver, B.C., Canada

The effective absorbed dose in photodynamic therapy is proportional to the concentration of the photosensitizer, as well as to the radiant energy fluence and concentration of oxygen. The concentration of dihematoporphyrin ether/ester (DHE) has been measured in tissue specimens by chemical extraction followed by spectrofluorimetry against a standard solution, and by an in vivo fluorometer probe calibrated ag...

JLA Vol:1 Iss:2 (New Materials: Non‐Equilibrium Synthesis by Laser)

Authors:
J. Mazumder
S. Sircar
C. Ribaudo
A. Kar
Laser‐Aided Materials Processing Laboratory, Department of Mechanical and Industrial Engineering, University of Illinois at Urbana‐Champaign, 1206 West Green Street, Urbana, Illinois 61801, U.S.A.

Synthesis of nonequilibrium phases provides an opportunity to engineer new materials with novel properties. The technique of laser surface modification (LSM) provides a unique means of synthesizing novel non‐equilibrium materials by taking advantage of the inherent rapid heating and cooling rate of the process. LSM can be used to obtain specific surface properties significantly diffe...

JLA Vol:1 Iss:2 (Optical Detection of Ultrasonic Disturbances)

Authors:
James W. Wagner
The Johns Hopkins University, Center for Nondestructive Evaluation, Maryland Hall 102, Baltimore, Maryland 21218

Optical methods for detection of ultrasonic signals offer the potential for performing noncontact and remote sensing for ultrasonic inspection and acoustic emission testing of materials and structures. These capabilities are of particular advantage for sensing applications at elevated temperatures or in hostile environments. While a number of optical detection methods have been employed in the past, most efforts have involved the development of interferometric techniques of one form or another. Technological advances in conventional and holographic...

JLA Vol:1 Iss:2 (Summary of Laser Plume Effects and Safety Session)

Authors:
Richard P. Felten
Senior Chemist, Radiation Biology Branch, Center for Devices and Radiological Health, Food and Drug Administration

JLA Vol:1 Iss:3 (Chemical Composition of Laser‐Tissue Interaction Smoke Plume)

Authors:
John M. Kokosa
GMI Engineering & Management Institute, Flint, Michigan 48504 U.S.A.

John Eugene
Beckman Laser Institute, Irvine, California 92715 U.S.A.

Lasers are assuming an increasingly important role in surgical procedures. However, several studies have shown that the smoke produced by laser‐tissue interaction is an airway irritant. Preliminary studies in our laboratories have shown that potentially hazardous chemicals, including benzene, formaldehyde and acrolein are present in the smoke plume resulting from CO₂ and Nd:YAG laser interaction with animal tissue, even at low power densities. Since these chemicals are classified a...