JLA Vol:3 Iss:2 (Mo Conductor Forming Technique with Laser Chemical Vapor Deposition (CVD))

Authors:
Shyuzo Sano
Mikio Hongo
Katsuro Mizukoshi
Takashi Kamimura
Production Engineering Research Laboratory, Hitachi, Ltd., Japan

A reduction in resistivity and an improvement in reliability of Mo conductors formed by laser CVD from Mo(CO)₆ gas have been achieved using laser annealing. By establishing a standard of 10 μ Ω • cm, the reduction in resistivity was analyzed by AES (Auger Electron Spectrometry) and XRD (X‐ray Diffractometry) methods. Reliability has been confirmed by the stability of resistance when subjected to a heat cycle of −50 – 150°C for more than 70 times.

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:3 Iss:2 (Laser Applications in Criminalistics)

Authors:
E. R. Menzel
Center for Forensic Studies, Department of Physics, Texas Tech University, Lubbock, Texas 79409

Lasers find application in numerous areas of criminalistics, such as fiber analysis, document examination and serology. Their widest use, however, is in detection of latent fingerprints. Several routine procedures for obtaining laser‐excited fingerprint fluorescence on a range of surfaces have been developed. However, many surfaces fluoresce so strongly themselves that they are not amenable to these procedures. Time‐resolved luminescence imaging is being investigated to permit detection of fingerprints on such surfaces.

JLA Vol:3 Iss:2 (Treatment of the Transplantable FANFT Induced Bladder Tumors with the Purpurin SnET2 and Red Light Emitted by a Pulsed Frequency Doubled Nd:YAG Laser)

Authors:
Steven H. Selman
David L. Fitkin
Rick W. Keck
Alan R. Morgan
Daniel R. Doiron

Photodynamic therapy of transplantable N‐[4‐(5‐nitro‐2‐furyl)‐2‐thiazolyl] formamide‐induced tumors engrafted onto Fischer CDF (F‐344)/CrlBR rats that had been sensitized with the photosensitizer tin (II) etiopurpurin dichloride was performed in combination with visible light (∼660 nm) emitted by either a continuous wave argon‐dye laser or a pulsed, frequency‐doubled Nd:Yag laser. Tumor control was assessed either by tumor dry‐weight 12 d...

JLA Vol:3 Iss:2 (Welding Zinc‐Coated Steel with a Laser and the Properties of the Weldment)

Authors:
Rehan Akhter
W. M. Steen
Dept. of Mechanical Engineering

K. G. Watkins
Dept. of Materials Science and Engineering, University of Liverpool, Liverpool L69 3BX, England

This paper discusses the lap welding of zinc‐coated mild steel sheet using a laser. This process is of great interest to the manufacturers of cars, washing machines and other components made from sheet steel and subject to corrosion. Conventional and high‐energy density welding of this material results in explosive ejection of the zinc vapor and an unsatisfactory weld. Several techniques are presented for the removal of the zinc from the interface or the control ...

JLA Vol:3 Iss:1 (Cutting of Al‐Alloys Using High‐Pressure Coaxial Nozzle)

Authors:
B. Biermann
S. Biermann
H. W. Bergmann
Forschungsverbund Lasertechnologie Erlangen (FLE), Martensstr. 5, 8520 Erlangen, West Germany

Aluminum alloys are used extensively in aerospace structures because of their high strength‐to‐weight characteristics. Unfortunately, these alloys are difficult to cut by laser processing. This behavior stems from: 1) their affinity for atmospheric gases, 2) their tendency to form high melting point reaction products and 3) the marked difference between their solidus and liquidus temperatures, which leads to formation of a mushy zone during cutting. This paper describes the results of a program directed t...

JLA Vol:3 Iss:1 (Laser Welding Copper and Copper Alloys)

Authors:
Kaoru Hashimoto
Takehiko Sato
Koichi Niwa
Fujitsu Laboratories Ltd., 10‐1, Morinosato‐Wakamiya, Atsugi 243‐01, Japan

We have developed a laser hermetic sealing technique that combines nickel plating with laser welding for copper and copper alloy bellows for general purpose large‐scale computers. Laser welding of copper has been difficult because of copper's high thermal conductivity and reflectivity. However, laser welding nickel‐plated copper results in deep penetration. To avoid corrosion induced at the dissimilar metal contact between nickel and copper, the nickel‐plated copper was heat‐treated bef...

JLA Vol:3 Iss:1 (Schmidt‐Cassegrain Optics For Laser Doppler Velocimetry Applications)

Authors:
Stephen E. Dunagan
National Full‐Scale Aerodynamics Complex, NASA‐Ames Research Center, Moffett Field, California, 94035 U.S.A.

A procedure is identified for adapting Schmidt‐Cassegrain telescope optics to perform the laser beam focusing and scattered light collection tasks associated with dual‐beam laser Doppler velocimetry. A generic, aperture‐normalized system is analyzed using ray‐tracing and Gaussian beam propagation analysis methods. Two relatively simple modification approaches are identified, each of which provides probe volume imaging performance near the diffraction limit. Similar modifications may be configured for laser b...

JLA Vol:3 Iss:1 (Two‐Color Particle‐Imaging Velocimetry)

Authors:
Larry P. Goss
Michael E. Post
Darryl D. Trump
Benjamin Sarka
Systems Research Laboratories, Inc., A Division of Arvin/Calspan, 2800 Indian Ripple Road, Dayton, OH 45440‐3696 U.S.A.

A novel experimental method for determining two‐dimensional velocity flowfields has been developed. The technique, two‐color particle‐imaging velocimetry (PIV), is similar to existing PIV techniques except that two different‐color laser sources are used to form the light sheets required for exposing the position of particles in a seeded flowfield. A green‐colored laser sheet (formed by a doubled Nd:YAG laser) and a re...

JLA Vol:3 Iss:1 (Developments in Medical Applications)

Authors: