JLA Vol:18 Iss:4 (Fabrication of waveguides in Foturan by femtosecond laser)

Authors:
Z. L. Li
D. K. Y. Low
M. K. Ho
G. C. Lim
Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075

K. J. Moh
Photonics Research Center, School of Electrical & Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798

We report two methods of fabricating waveguides in photosensitive Ag⁺ doped Foturan glass by femtosecond laser writing and subsequent annealing. The first method involves writing at laser energies higher than the optical breakdown threshold, directly resulting in microstructural changes and a refractive index increase. In contrast...

JLA Vol:18 Iss:4 (Influence of joint geometry and fit-up gaps on hybrid laser-metal active gas (MAG) welding)

Authors:
Y. Yao
Jilin University and China FAW Group Corporation R&D Center, No. 35 Chuangye Street, 130011 Changchun, China

M. Wouters
Luleå University of Technology, Division of Manufacturing Systems Engineering, S-971 87, Luleå, Sweden

J. Powell
Luleå University of Technology, Division of Manufacturing Systems Engineering, S-971 87, Luleå, Sweden and Laser Expertise Ltd., Acorn Park Ind. Estate, Harrimans Lane, Nottingham NG7 2TR, United Kingdom

K. Nilsson
A. F. H. Kaplan
Luleå University of Technology, Division of Manufacturing Systems Engineering, S-971 87, Luleå, Sweden

...

JLA Vol:18 Iss:4 (Laser clad WC reinforced Ni-based intermetallic-matrix composites to improve cavitation erosion resistance)

Authors:
Muthukannan Duraiselvam
Institut fu¨r Schweißtechnik und Trennende Fertigungsverfahren, Technische Universita¨t Clausthal, Agricolastraße 2, 38678 Clausthal-Zellerfeld, Germany

Rolf Galun
Institut fu¨r Werkstoffkunde und Werkstofftechnik, Technische Universita¨t Clausthal, Agricolastraße 6, 38678 Clausthal-Zellerfeld, Germany

Volker Wesling
Institut fu¨r Schweißtechnik und Trennende Fertigungsverfahren, Technische Universita¨t Clausthal, Agricolastraße 2, 38678 Clausthal-Zellerfeld, Germany

Barry L. Mordike
Institut fu¨r Werkstoffkunde und Werkstofftechnik, Technische Uni...

JLA Vol:18 Iss:4 (Sealing of human dentinal tubules by KrF 248 nm laser radiation)

Authors:
M. Sivakumar
V. Oliveira
R. Vilar
Departmento Engenharia Materiais, Instituto Superior Te´cnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal

S. Oliveira
J. Leita˜o
Faculdade de Medicina Denta´ria, Universidade de Lisboa, Campus Universita´rio, Cidade Universita´ria, 1649-003 Lisboa, Portugal

Exposure of dentinal tubules is a common cause of dental hypersensitivity to thermal, mechanical, or chemical stimuli. Treatment for this syndrome should be fast, painless on application, and long lasting, but most treatments presently available are ineffective or relatively short lived. The aim of ...

JLA Vol:18 Iss:4 (Simulated fabrication of off-axis microlens array using excimer laser dragging process)

Authors:
Shuh-Yi Wang
Department of Mechanical Engineering, Chengshiu University, 840 Cheng Ching Road, Niaosung, Kaoushiung, 833, Taiwan, Republic of China

A computer simulation of the fabrication of an off-axis aspheric microlens array using excimer laser dragging with variously shaped masks is performed. Traditionally, a semicircular mask is used during dragging to yield an on-axis microlens array. However, a quarter-circular mask can generate an off-axis microlens array using this dragging process. Unlike the more common centered or on-axis system, this off-axis microlens array can process focused light without obstructing the lens. Variously shaped masks were computer simulated. ...

JLA Vol:18 Iss:4 (Studies on the use of offset and angled prescores for fracture control during laser machining of alumina ceramics)

Authors:
A. E. Segall
G. Cai
R. Akarapu
Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802

While lasers offer many advantages when machining ceramics, micro- to macroscale damage often culminating in premature fractures is a shortcoming that cannot be ignored by manufacturers, especially during higher-speed machining where supports are not practical. As detailed in earlier studies, such macroscale fractures can be controlled by simultaneously scoring and cutting. Indeed, by using a lower-power beam to simultaneously create a shallow groove or prescore directly ahead of the higher-power cutting beam, the f...

JLA Vol:18 Iss:4 (Study of laser assisted decontamination of commonly used clad surfaces)

Authors:
J. P. Nilaya
Aniruddha Kumar
P. Raote
M. B. Sai Prasad
D. J. Biswas
Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai-400085, India

The decontamination factor, defined as the ratio of initial to residual activity, is studied as a function of laser fluence for three kinds of clad surfaces viz., plain zircaloy, autoclaved zircaloy, and stainless steel with cesium as the simulated contamination. It has been found that the decontamination factor exhibits a maximal behavior with the laser fluence and its maximum value occurs at different laser fluences in the three cases. The maximal behavior is attribut...

JLA Vol:18 Iss:4 (Threshold powers and delays for igniting propane and butane-air mixtures by cw laser-heated small particles)

Authors:
Thomas H. Dubaniewicz
National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory, 626 Cochrans Mill Road, Pittsburgh, Pennsylvania 15236

The National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory conducted a study of laser safety in potentially flammable environments. Researchers measured threshold igniting powers as a function of beam diameter for butane and propane-air mixtures by laser-heating targets placed on optical fiber tips using a 1064 nm laser. The minimum igniting powers for propane-air and butane-air were about 250 and 300 mW, respectively. Threshold igniting powers for propane-air were approxima...

JLA Vol:19 Iss:1 (Calculation of the fluence of the five layers of the cervix of the rabbit with Taylor approximation)

Authors:
Samia Bouzid
Laboratory of Lasers and Applications, Faculty of Medicine, University of Constantine, Algeria

The microtome has allowed us to observe the uterine extra cervix of the rabbit. This latter is covered with a none keratinized stratified malpighian epithelium made up of five layers. The laser-cervix interaction allows us to calculate, by the resolution of the radiative transport equation with Taylor approximation, the fluence rate of each layer. The whole fluence rate is determined by using the optic properties of each layer. These optic properties are obtained by fitting the transmittances measured and calculated by the Monte Carlo method. The obtained results are gi...

JLA Vol:19 Iss:1 (Combining high-speed laser perforation and cold roll forming for the production of biomedical microfiltration membranes)

Authors:
M. Baumeister
K. Dickmann
Laser Center University of Applied Sciences Muenster (LFM), Stegerwaldstrasse 39, 48565 Steinfurt, Germany

A. P. Hoult
SPI, 3 Wellington Park, Tollbar Way Hedge End, Southampton SO30 2QU, United Kingdom

A novel high speed two-step technique capable of performing large matrices of very small pores with micron dimensions in large sheets of thin stainless steel foils has been developed. This process combination is initiated by high-speed “on-the-fly” laser perforation. A 100 W fiber laser is capable of a very high drilling rate making it an attractive option for the creation of large drilling matrices ...