JLA Vol:9 Iss:3 (Experimental study of cutting thick aluminum and steel with a chemical oxygen–iodine laser using an N₂ or O₂ gas assist)

Authors:
David L. Carroll
James A. Rothenflue

A chemical oxygen–iodine laser (COIL) was used to cut aluminum and carbon steel. Cut depths of 20 mm in aluminum and 41 mm in carbon steel were obtained using an N₂ gas assist and 5–6 kW of power on target. The same laser at the same power level produced a cut depth of 65 mm in carbon steel with an O₂ gas assist; a low quality cut to a depth of nearly 100 mm in carbon steel was also demonstrated. These data are compared with existing COIL and CO₂ laser cutting data. COIL cuts carbon steel and stainless steel at approximately the same rate. For a given cut depth, power and spot size...

JLA Vol:4 Iss:2 (Dynamic Laser Doppler Velocimetry on Solid Surfaces)

Authors:
Milind M. Rajadhyaksha
Warren H. Stevenson
Applied Optics Laboratory, School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907, U.S.A.

This paper presents the results of a detailed analytical and experimental investigation into the accuracy of a differential laser Doppler velocimeter (LDV) for dynamic, solid surface velocity measurements made over very short averaging times on the order of one millisecond. Accuracy limitations are derived, along with operating conditions and signal processing considerations needed to optimize LDV performance. An experiment is described which demonstrates the use of an LDV to instantaneously and accurate...

JLA Vol:16 Iss:2 (High-power CO₂ laser design “from resonator end mirror to cutting lens focal point”)

Authors:
David Toebaert
HACO NV, Oekenestraat 120, 8800 Rumbeke, Belgium

Wybo Wagenaar
Infinite Simulation Systems BV, Lange Bunder 3, 4854 MB Bavel, Netherlands

An algorithm is derived that allows calculating all optical parameters relevant to the design of a high-power CO₂ laser, taking into account the practical needs of a flying-optics type of laser cutting machine. The novelty of the approach taken is that the resonator and the beam delivery optics are treated simultaneously, which allows for greater flexibility in design. To begin with, the often-used optical configuration of a stable resonator combined with a beam expander for collimation is mod...

JLA Vol:20 Iss:3 (Investigation of femtosecond laser induced thermal ablation of polyethylene)

Authors:
Andrew J. Lee
Judith M. Dawes
Michael J. Withford
Centre of Ultrahigh-bandwidth Devices for Optical Systems (CUDOS) and MQPhotonics Research Centre, Department of Physics, Macquarie University, 2109 NSW, Australia

We present a novel method for profiling high aspect ratio and undercut laser drilled holes using sacrificial layers. This profiling method is used to compare and contrast laser ablation of polyethylene films under exposure to ultraviolet (266 nm) and near-infrared (800 nm) radiation from an ultrafast, femtosecond laser. We find that ultraviolet femtosecond pulsed laser processing of this polymer exhibits similar characteristics to...

JLA Vol:23 Iss:3 (Parameter optimization of a laser-induced fluorescence system for <em>in vivo</em> screening of oral cancer)

Authors:
V. K. Unnikrishnan
Rajesh Nayak
Rodney Bernard
Centre for Atomic and Molecular Physics, Manipal University, Manipal, 576 104, India

K. Jeena Priya
Department of Oral Medicine and Radiology, MCODS Mangalore, Manipal University, Manipal, 575 001, India

Ajeetkumar Patil
Centre for Atomic and Molecular Physics, Manipal University, Manipal, 576 104 India

J. Ebenezer
PG & Research Department of Physics, Jamal Mohamed College, Tiruchinapalli, Manipal, 620 020, India

Keerthilatha M. Pai
Department of Oral Medicine and Radiology, MCODS Manipal, Manipal University, Manipal,576 104 India<...>

JLA Vol:6 Iss:1 (Measurement of temperature and absorptance for laser processing applications)

Authors:
S. Ramanathan
M. F. Modest
Department of Mechanical Engineering, The Pennsylvania State University, University Park, PA 16802, U.S.A.

The use of CO₂ lasers has been successfully demonstrated for several manufacturing processes such as cutting, drilling, scribing, etc., of a wide range of materials. The absorptance of a material at the laser wavelength and at the material removal temperature substantially affect the efficiency of the laser machining process. Some materials have absorption bands in the mid&hyphen;infrared and the absorptance changes drastically with temperature at the CO₂ laser wavelength of 10.6 μm. Additionally, the absor...

JLA Vol:14 Iss:3 (Pulsed laser driven deposition of spattered molten particles and its application to the manufacturing of wear-resistant coatings)

Authors:
Toru Nagai
Takashi Inoue
Applied Laser Engineering Research Institute, 2085-16 Uenoyama, Fukasawa, Nagaoka 940-2135, Japan

Hirofumi Shimura
Mechanical Engineering Laboratory, Agency of Industrial Science and Technology, 1-2 Namiki, Tsukuba 305-8564, Japan

In this article, we report on a new process for manufacturing metal coatings with submillimeter thickness by pulsed laser driven deposition of molten metal particles. The process of “laser spattering of molten particles” using a high pulse-energy laser is considered to be effective compared to the conventional physical vapor process based on vaporized ultrafine particle generati...

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:25 Iss:4 (Analysis of Yb:YAG thin disk laser resonator considering thermal lens effects: Experimentally and by Laser Cavity Analysis and Design)

JLA Vol:8 Iss:2 (Laser materials processing at Sandia National Laboratories)

Authors:
James L. Jellison
Michael J. Cieslak
Sandia National Laboratories, Albuquerque, NM 87185, U.S.A.

This paper describes the laser materials processing capabilities at Sandia National Laboratories. Some of the advances in the understanding of various aspects of laser materials processing which have been made by the laser materials processing team at Sandia are discussed.