JLA Vol:15 Iss:2 (Laser surface processing of titanium in air: Influence of scan traces overlapping)

Authors:
A. Pe´rez del Pino
P. Serra
J. L. Morenza
Departament de Fı´sica Aplicada i Òptica, Universitat de Barcelona, E-08028 Barcelona, Spain

Laser surface treatments of titanium in air have been performed through a pulsed Nd:yttrium–aluminum–garnet (λ=1.064 μm) laser. Several samples have been obtained modifying the laser scan velocity and partial overlapping of consecutive traces, in order to study the influence of these parameters on the surface morphology. Scanning electron microscopy and profilometry measurements have revealed different surface morphologies depending on the physical processes involved in th...

JLA Vol:19 Iss:2 (Intrabeam viewing of extended-source lasers with telescopes)

Authors:
Wesley J. Marshall
E. Christopher Brumage
David H. Sliney
U.S. Army Center for Health Promotion and Preventive Medicine, AberdeenProving Ground, Maryland 21010-5403

Magnifying optics can increase the hazards for intrabeam viewing of lasers. Although it is rather straightforward to evaluate these increased hazards for point-source lasers at distance, limited information is available for determining the hazards from viewing extended-source lasers from within the beam when magnifying optics are used. Since intrabeam viewing of nearly all lasers results in an extremely small retinal image, commonly known as a “point source,” extended-source m...

JLA Vol:8 Iss:5 (Taking advantage of laser properties to enhance demonstrations and student laboratories)

Authors:
Michele L. Brill
Camden County College — Physics/Lasers, Box 200, Blackwood, NJ 08012, U.S.A.

This paper reflects the proceedings of a workshop for local educators provided by Camden County College Laser Curriculum faculty which addressed the question: ‘How can the teacher take advantage of laser properties to improve or enhance demonstrations and student labs?’ Explored here are illustrative ways in which to utilize, for educational purposes, the three well‐known characteristics of lasers: directionality, monochromaticity, and coherence. There is a faculty overlap between the Physics Department and the Laser Curriculum faculty at the college. The use...

JLA Vol:2 Iss:1 (Laser Laparoscopy Contamination)

Authors:
Douglas E. Ott
420 Charter Blvd. Macon, Georgia 31210

JLA Vol:17 Iss:4 (Temperature distributions due to annular laser beam heating)

Authors:
D. Zeng
Laser-Aided Manufacturing, Materials and Micro-Processing (LAMMMP) Laboratory, College of Optics and Photonics, Center for Research and Education in Optics and Lasers (CREOL), Mechanical, Materials and Aerospace Engineering Department, University of Central Florida, Orlando, Florida 32816-2700

W. P. Latham
Air Force Research Laboratory, Directed Energy Directorate, 3550 Aberdeen, Avenue SE, Kirtland Air Force Base, New Mexico 87117-5776

A. Kar
Laser-Aided Manufacturing, Materials and Micro-Processing (LAMMMP) Laboratory, College of Optics and Photonics, Center for Research and Education in Optics and Lasers (CREOL), Mechanical, Materials and ...

JLA Vol:22 Iss:2 (Studies on characteristics of CO₂ laser-GTAW hybrid welding of austenitic stainless steel)

Authors:
Rakesh Kaul
Harish Kumar
B. T. Rao
L. M. Kukreja
Laser Material Processing Division, Raja Ramanna Centre for Advanced Technology, P.O. CAT, Indore 452 013, India

Nageshwar Singh
H. S. Vora
Laser System Engineering Division, Raja Ramanna Centre for Advanced Technology, P.O. CAT, Indore 452 013, India

The present paper describes an experimental hybrid welding study, involving CO₂ laser and gas tungsten arc welding, on 6 mm thick austenitic stainless steel sheet. The study focused on real-time plasma monitoring during welding and metallographic examination of the resultant weldments. Coupling of...

JLA Vol:26 Iss:1 (Periodic antireflection surface structure fabricated on silicon by four-beam laser interference lithography)

Authors:
Z. Zhang
CNM and JR3CN, Changchun University of Science and Technology, Changchun 130022, China and CHO, Changchun Observatory, National Astronomical Observatory, CAS, Changchun 130117, China

Z. Wang
D. Wang
CNM and JR3CN, Changchun University of Science and Technology, Changchun 130022, China and JR3CN, University of Bedfordshire, Luton LU1 3JU, United Kingdom

Y. Ding
CNM and JR3CN, Changchun University of Science and Technology, Changchun 130022, China

Silicon surface structures with excellent antireflection property arouse wide interest. Chemical and physical methods such as femtosecond, nanosecond, and picosecond la...

JLA Vol:9 Iss:1 (Continuous wave Nd:YAG laser cladding modeling: A physical study of track creation during low power processing)

Authors:
J‐.M. Jouvard
D. F. Grevey
F. Lemoine
A. B. Vannes

This paper concerns the modeling of cladding using an Nd:YAG laser operating at low powers typically less than 800 W. Experimental observation of the evolution of the mass of the clads shows two power thresholds. The theoretical study relies on a calculation of the fluence provided to the substrate and on a model of heat transfer into the substrate. We suggest that the first threshold is the power required for substrate melting. The second power is the threshold when the powder is directly melted by the beam and is therefore a liquid when contacting the substrate.

JLA Vol:4 Iss:3 (Laser Safety Primer Outline for Industrial/Medical Users)

Authors:
T. J. Glynn
M. Walsh
National Centre for Laser Applications, Physics Dept., University College, Galway, Ireland

Laser safety standards are detailed technical documents arising from the complexity of the different mechanisms, depending on the parameters of the laser beam, by which lasers interact with living tissue. As a result, their interpretation by non‐expert laser users, who are concerned about safety issues, can cause many difficulties. Based on experience in advising industrial and medical laser users, we have developed a primer which (i) provides step‐by‐step guidance in the interpretation and use of the laser saf...

JLA Vol:16 Iss:1 (Laser-assisted chemical cleaning for oxide-scale removal from carbon steel surfaces)

Authors:
Hyunkyu Lim
Dongsik Kim
Department of Mechanical Engineering, POSTECH, Pohang 790-784, Korea

The article introduces a novel laser chemical processing technique for removing thin oxide layers on low-carbon steel surfaces by combining laser-induced shock waves and the chemical cleaning technique that is currently utilized in the conventional oxide-scale removal. A Q-switched Nd:yttritium–aluminum–garnet laser (wavelength 1064 nm, full width at half maximum 6 ns) induces optical breakdown in the acid solution, producing intense pressure waves which act as a noncontact scale breaker. It has been demonstrated that the novel process leads to substa...