JLA Vol:2 Iss:2 (Binary Phase Gratings for Materials Processing)

Authors:
Paul J. Patt
Array

The feasibility of using a diffractive optical element, a phase grating, as a beam handling device for use in industrial laser material processing is examined. The binary phase grating is an efficient beam splitting device and is useful in many materials processing operations (welding, cutting, soldering, drilling) where a high degree of parallelism could significantly improve process throughput. Overall efficiency of etched quartz binary gratings agrees well with published predictions (nominal 70–90%). Copies of the grating formed in PMMA (acrylic) survived preliminary life tests (more than 1000 9‐J pulses from a commercial multimode N...

JLA Vol:2 Iss:3 (Erbium:YAG (2.94 &mu;<em>m) Laser Effects on Dental Tissues</em>)

Authors:
James A. Hoke
E. Jeff Burkes
Edward D. Gomes
Myron L. Wolbarsht

Past trials with soft and calcified tissues have demonstrated that long pulse train (2.5 μs) Er:YAG (2.94 μm) laser may be used to ablate tooth structure of human teeth. Determination of physical and thermal damage to surrounding tissue during removal of enamel and dentin is a primary objective of this study. Extracted human teeth with thermal probes imbedded in the pulp chambers were submitted to cavity preparation using an Erbium YAG laser with water mist. Wavelength selection as well as use of a water mist during the procedure resulted in efficient tissue...

JLA Vol:2 Iss:3 (Laser Surgery: Organs to Organelles)

Authors:
Michael W. Berns
Beckman Laser lnstitute and Medical Center

JLA Vol:2 Iss:3 (The American Society for Laser Medicine &amp; Surgery Presents the William B. Mark Award to Michael W. Berns)

Authors:
Caroline S. Mark

JLA Vol:2 Iss:3 (On Optical Methods in Particle Flow)

Authors:
I. Shimizu
Dept. of Mechanical Engineering, Ibaraki College of Technology, Katsuta 312, Japan

Wen&hyphen;Jei Yang
Dept. of Mech. Eng. and Applied Mech., University of Michigan, Ann Arbor, Michigan 48109

Some recently developed optical methods for the measurement, control and shape recognition of particle flow are presented including motion control of micro&hyphen;particles by optical pressure, identification of particle groups by matched spatial filters, bidirectional light scattering/image processing, bidirectional light scattering/real time measurement, dual beam type particle counter, and speckle photography.

JLA Vol:2 Iss:3 (Current State&hyphen;of&hyphen;the&hyphen;Art of Contouring Techniques in Manufacturing)

Authors:
Kevin G. Harding
Industrial Technology Institute, Sensor Center for Improved Quality, Ann Arbor, Michigan 48106

A manager with a major automobile manufacturer once made the comment that “the best thing we ever did to improve quality was give the guys on the floor a caliper to measure the parts”. As the tolerances on manufacturing become tighter, the need for accurate measurement has also increased. Hand fitting of parts to each other does not work in modern automated factories. Gauges in the past have been built to provide a fixed set of measurements of a known part. This practice too has been changing due to the trend toward flexible manufacturing. Now the gages...

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&hyphen;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:3 (Cooperative R&amp;D Project: Laser Biomedical Subsurface Imaging)

Authors:
Leon Goldman
J. H. Kerr
Department of Dermatology, Naval Hospital, San Diego, California 92134&hyphen;5000

With the experience of the U.S. Navy in photon transmission through turbid media, a cooperative research and development project has been initiated for laser subsurface imaging. This concerns laser expertise, laser institutes, and consultants. The initial technologies considered at present are laser transmission with chromophores, including photodynamic therapy, spectroscopy, biomedical optical phase conjugation, pulsed thermal radiometry of Nelson, digital ultrasound with hopeful laser additive imagery, and MRI with holography and radiowaves. Laser transil...

JLA Vol:3 Iss:3 (Comparison of the CDRH and IEC Standards for Laser Products. Part I)

Authors:
Jerome E. Dennis
Center for Devices and Radiological Health, Food and Drug Administration, Rockville, Maryland

David H. Edmunds
Xerox Corporation, Webster, New York

JLA Vol:3 Iss:3 (Safety of Medical Excimer Lasers with an Emphasis on Compressed Gases)

Authors:
David H. Sliney
Laser Microwave Division, US Army Environmental Hygiene Agency, Aberdeen Proving Ground, MD 21010&hyphen;5422

Terrance N. Clapham
VISX, Inc., 919 Kifer Road, Santa Clara, CA 94086

Excimer lasers which emit short ultraviolet radiation (UVR) are currently being used in experimental and developmental surgical applications. Although UVR exposure is possible, it is not normal in laser angioplasty (cardiovascular surgery) and is insignificant in photokera&hyphen;toplasty (ophthalmic surgery). However, significant potential hazards exist with the use of excimer laser gases such as fluorine and HCI. Stringent safeguards for handling and use are ...