JLA Vol:25 Iss:5 (Numerical and experimental study of the effect of groove on plasma plume during high power laser welding)
Shanghai Jiao Tong University, Dongchuan Road 800, Shanghai 200240, China and Shanghai Key Laboratory of Materials Laser Processing and Modification, Shanghai 200240, China
The influence of groove on the static feature and dynamic behavior of plasma plume during high power CO2 laser welding process was studied using a hydrodynamic three-dimensional model and corresponding experiments. The temperature, composition, and velocity of plasma plume along the incident path of laser beam were computed. The static morphology of plasma plume was analyzed through both models ...
Kaushik M. Phatak
F. W. Liou
Department of Mechanical and Aerospace Engineering, University of Missouri-Rolla, Rolla, Missouri 65409-1350
Laser aided deposition is a material additive based manufacturing process via metallurgically bonding the deposited material to the substrate. Due to its capability to bond various materials together, it becomes an attractive technology for part repair in small scale. However, the details of the process remain an active area for research because of the complicated interactions involved. In this study, a mathematical model was established to investigate thermal and mass transportation phenomena, which incl...
Department of Physics, University of California, Berkeley, California 94720
JLA Vol:8 Iss:3 (Commonwealth of Independent States (CIS) laser scene and Laser Association (LAS) activities)
Ivan B. Kovsh
LAS Headquarters, Moscow, Rozhdestvenkastr, 27, 117485, Russia
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...
R. E. Mueller
W. W. Duley
CRESS and Laser Processing Laboratory, York University, Toronto, Ontario, Canada M3J 1P3
Canadian Astronaut Office, National Research Council, Ottawa, Ontario, Canada K1A 0R6
W. F. J. Evans
Atmospheric Environment Service, 4905 Dufferin Street, Downsview, Ontario M3H 5T4
Initial results of a series of laser processing experiments performed under the micro‐gravity conditions supplied by NASA's KC‐135 aircraft are presented. Weld morphologies of polypropylene and polyethylene were obtained under both hyper‐ and hy...
Joakim Ilsing Sørensen
Flemming O. Olsen
Manufacturing Engineering and Management, Materials and Process Technology, Technical University of Denmark, Building 425, DK-2800 Lyngby, Denmark
In this article, a new approach based on induction heat treatment of flat laser welded sheets is presented. With this new concept, the ductility of high strength steels GA260 with a thickness of 1.8 mm and CMn with a thickness of 2.13 mm is believed to be improved by prolonging the cooling time from 750 to 450 °C. Initially, a simple analytical model was used to calculate the ideal energy contributions from a CO2 high power laser s...
JLA Vol:19 Iss:4 (Ablation and cutting of silicon wafer and micro-mold fabrication using femtosecond laser pulses)
Wuhan National Laboratory for Optoelectronics and School of Optoelectronics Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China
Femtosecond laser micromachining of silicon wafer at a relatively higher energy fluence level (>50 J/cm2) is investigated. Laser ablating spots and cutting kerfs are examined by means of charge coupled device camera and scanning electron microscopy. The area of ablated spots increases linearly with increasing the shot number from 1 to 16 and shows saturation with t...
The formation of laser-induced periodic surface structures (LIPSS) in different materials (metals, semiconductors, and dielectrics) upon irradiation with linearly polarized fs-laser pulses (τ ∼ 30–150 fs, λ ∼ 800 nm) in air environment is studied experimentally and theoretically. In metals, predominantly low-spatial-frequency-LIPSS with periods close to the laser wavelength λ are observed perpendicular to the polarization. Under specific irradiation conditions, high-spatial-frequency-LIPSS with sub-100-nm spatial periods (∼λ/10) can be gene...
IBM Corporation, GTD, Hopewell Junction, New York
Since the early 1980's discovery of the ability of excimer lasers to etch polymers precisely and cleanly with minimal thermal damage, excimer lasers have been used actively in the semiconductor industry for various manufacturing processes. In the present study a process for laser cutting of polymers has been investigated. A laser beam of controlled cross‐sectional shape is imaged onto a polymer surface. The geometry of the cutting path is controlled by precise movement of a sample mounted on a 2‐axis computer controlled work stage. This type of a process is useful for applications ...
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