JLA Vol:7 Iss:1 (Development of laser finishing for non‐circular profiles)

Authors:
Ko‐Wang Liu
Paul S. Sheng
Department of Mechanical Engineering, University of California, Berkeley, CA 94720‐1740, U.S.A.

A laser‐based technique for finishing of non‐circular cylindrical parts is presented. In this process, the frequency characteristics of a desired non‐circular shape is extracted from a CAD through a Fast Fourier Transform algorithm and implemented through a CO₂ laser machining system. A galvanometer‐based scanner is used in the process to achieve programmable beam trajectories and high‐speed finishing. An error estimation scheme can be developed to determine the final dimensional erro...

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: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: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: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: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:26 Iss:1 (Two-dimensional simulation of laser ablation with 235 nanosecond pulses)

Authors:
Sousan Ghalamdaran
Iranian National Centre for Laser Science and Technology (INLC), PO Box 14665-576 Tehran, Iran and Department of Physics, Amir Kabir University of Technology, PO Box 15875-4413 Tehran, Iran

Parviz Parvin
Department of Physics, Amir Kabir University of Technology, PO Box 15875-4413 Tehran, Iran

Mohamad Javad Torkamany
Jamshid Sabbagh Zadeh
Iranian National Centre for Laser Science and Technology (INLC), PO Box 14665-576 Tehran, Iran

A two-dimensional thermal model of nanosecond pulsed laser ablation is developed to describe the physical processes, the plasma absorption, the crater profile, and the temp...

JLA Vol:23 Iss:2 (Experimental investigation of laser shock peening using femtosecond laser pulses)

Authors:
Dongkyun Lee
Elijah Kannatey-Asibu
Department of Mechanical Engineering, The University of Michigan, Ann Arbor, Michigan 48105-2125

In this study, the feasibility of laser shock peening using ultrafast laser pulses was experimentally investigated. A top coating of zinc with a water confining layer was applied in the investigation. The zinc coating was used for the thermoprotective effect. A high numerical aperture (NA≅0.5) aspheric lens was used to minimize the optical breakdown of water. Microhardness measurements were made on the top surface of the shock peened specimen and compared with the original material hardness. The results provide useful insight on...

JLA Vol:16 Iss:4 (Laser assisted cleaning of oxide films on SUS409 stainless steel)

Authors:
H. Guo
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802

R. Martukanitz
Applied Research Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802

T. DebRoy
Department of Materials Science and Engineering, The Pennsylvania State Univeristy, University Park, Pennsylvania 16802

Laser assisted cleaning of oxide films on SUS409 stainless steel plates was studied both experimentally and theoretically. The highly oxidized surfaces with oxide scales of about 25 μm thickness were irradiated with Q-switched pulsed Nd:yttritium–aluminu...

JLA Vol:7 Iss:3 (Laser beam surveying, refractive index measurements and the making of a 360° reflection hologram)

Authors:
David Foster
Notre Dame High School, 596 South Second St., San Jose, California 95112, U.S.A.

Triangulation measurements, using a laser to find the height of a room and of buildings, will be described first. This will be followed by triangulation and laser beam divergence measurements for range finding. The use of a hollow prism to hold liquids, whose refractive indicies are to be found, will then be described. The final topic will describe how a 360° reflection hologram was made at Notre Dame High School, utilizing three lasers and beam spreaders and four lasers and beam spreaders. The 360° hologram, made by a student, will be available for viewing.