Bekir S. Yilbas¸
Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
In an experimental investigation of laser–metal interaction, one of the important parameters is the propagation velocity of the liquid–vapor interface. The quantity appears as a direct result of the theoretical examination of the interaction and may be used to test the accuracy of the theory. Consequently, in the present study, the nature of the interaction mechanism between a pulsed laser beam and metals is examined using streak photographs of the ejecta from four metals: titanium, tantalum, nickel, and EN58B stainless steel. It...
JLA Vol:7 Iss:4 (Laser Applications in Science Education (LASE) Project at Santa Teresa High School)
James D. Sagray
Science Department, Santa Teresa High School, San Jose, California 95123, U.S.A.
The goal of the Laser Applications in Science Education (LASE) Project, centered at San Jose State University, is to bring significant laser technology and optics to the secondary level with a special emphasis on student research and publication. Its implementation at Santa Teresa High School has focused on permitting all students in physics classes (32/period) to experience laser labs in small groups working throughout the classroom. In addition to receiving this exposure, all physics students are encouraged to do original research projects and to compete for cash or other prize...
JLA Vol:7 Iss:4 (Laser applications in science education (LASE) Project: an introduction to photonics at the secondary school level)
Gareth T. Williams
Physics Department, San Jose State University, San Jose, California, U.S.A.
JLA Vol:7 Iss:4 (Laser cutting of thick sectioned steels using gas flow impingement on the erosion front)
P. M. Ilavarasan
P. A. Molian
Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, U.S.A.
An off‐axial gas jet has been developed that has the potential to extend the laser's effectiveness by improving the rate at which parts can be machined, producing high‐quality surfaces, enhancing the cutting thickness, and adding to the range of materials that can be machined. In laser cutting, an erosion front (liquid–gas region) forms at the momentary end of the cut. Laser heating, exothermic reactions and shear force between the gas flow and the molten layer dictate the material removal rates. The principle of the off‐axi...
JLA Vol:7 Iss:4 (Laser machining of ablating materials — overlapped grooves and entrance/exit effects)
Michael F. Modest
A three‐dimensional conduction model has been developed to predict the transient temperature distribution inside a thick solid that is irradiated by a moving laser source, and the changing shape of single or overlapping grooves carved into it by evaporation of material. The laser may operate in CW or in pulsed mode (with arbitrary temporal intensity distribution) and may have an arbitrary spatial intensity profile. The governing equations are solved, for both constant and variable thermophysical properties, using a finite‐difference method on a boundary&...
Gary K. Lewis
David A. Cremers
C. E. Albright
B. E. Wilde
A new method to produce iron‐noble metal surface alloys is described. Quenched‐and‐tempered AISI 4135 steel was electroplated with Pd, Pt and Au and laser surface melting was carried out to produce the respective surface alloys. CW CO2 laser power levels of 50, 100 and 200 W were employed. Auger depth profiling showed that alloying was achieved with Pt and Pd at all three power levels, but only at 200 W with Au.
JLA Vol:8 Iss:1 (Comparison of aluminum alloy welding characteristics with 1 kW CO and CO<sub>2</sub> lasers)
Bu¨lent A. Mehmetli
Institute of Research and Innovation, Laser Laboratory 1201 Takada, Kashiwa‐shi, Chiba 277, Japan
Welding characteristics of various aluminum alloys (A1100, A2017, A5083, A6063, A7N01) are investigated with CW CO and CO2 lasers near 1 kW power level. The beam characteristics of both lasers at the welding point are similar, so that a comparison can be made of the effect of the wavelength difference. The welding characteristics are assessed by measuring the size of the weld bead. It is found that the threshold power between heat‐conduction and deep‐penetration typ...
The acoustic emissions from laser lap welds in stainless steel sheet were recorded and analyzed. The acoustic signals emanating from the weld were sensed with an instrument microphone and analyzed using short‐time Fourier spectra to characterize their time‐frequency distributions. It was determined that the acoustic spectrum of good‐quality, full‐penetration welds could be differentiated from the spectra of poor‐quality welds, defined as either partial‐penetration welds or welds having a gap between the sheets being joined. A novel, relatively simple class...
Vi´ctor Fajer Avila
Center for the Development of Scientific Equipment and Instruments, Ministry of Science Techonology and Environment, Havana, Cuba
Research carried out in Cuba has led to the design and construction of automatic polarimeters that use the He‐Ne laser as a luminous source and work on a magnetooptic principle of measurement. Physical and chemical investigations including the use of the He‐Ne laser as a light source are discussed. The principle of measurement for the design and construction of polarimeters, resulting in three different types of these instruments, is described. Finally, applications for magnetooptic polarimetry are described,...