JLA Vol:21 Iss:3 (Multibeam fiber laser cutting)

Authors:
Flemming Ove Olsen
Klaus Schuett Hansen
Jakob Skov Nielsen
Department of Mechanical Engineering, Technical University of Denmark, Kongens Lyngby DK-2800, Denmark

The appearance of the high power high brilliance fiber laser has opened for new possibilities in laser materials processing. In laser cutting this laser has demonstrated high cutting performance compared to the dominating cutting laser, the CO₂ laser. However, quality problems in fiber-laser cutting have until now limited its application to metal cutting. In this paper the first results of proof-of-principle studies applying a new approach (patent pending) for laser cutting with h...

JLA Vol:21 Iss:3 (Pulsed laser deposition of lanthanum phosphate protective films)

Authors:
Sucharita Sinha
Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India

T. R. G. Kutty
Radiometallurgy Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India

P. V. A. Padmanabhan
Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India

K. G. K. Warrier
Regional Research Laboratories, Thiruvananthapuram, 6954019 Kerala, India

Pulsed laser deposition (PLD) technique has been successfully employed to generate thin film coating of lanthanum phosphate on various substrates. Sintered targets of lanthanum phosphate wer...

JLA Vol:21 Iss:3 (Shear bond stress of composite bonded to excimer laser treated dentin)

Authors:
M. Sivakumar
V Oliveira
R. Vilar
Depto. Engenharia Materiais, Instituto Superior Te´cnico, Universidade Te´cnica Lisboa, Av. Rovisco Pais n. 1, 1049-001 Lisboa, Portugal

S. Oliveira
Faculdade Medicina Denta´ria, Universidade Lisboa, Cidade Universita´ria, 1648-003 Lisboa, Portugal

The aim of this work was to study the bond strength of resin composite bonded to dentin surfaces treated with KrF excimer laser radiation, untreated surfaces, and acid-etched surfaces using a single-plane shear method. Dentin specimens cut from freshly extracted permanent molar teeth were subjected to laser treatment with a KrF ...

JLA Vol:21 Iss:4 (Contributions of Charles Townes’ research to nonlinear optics)

Authors:
Elsa Garmire
Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755, USA

Nonlinear optics was profoundly influenced by early work of Charles Townes and his group at Massachusetts Institute of Technology from 1961 to 1967. His foundational contribution was the realization that coherent molecular oscillations resulted from stimulated Raman scattering, leading to the introduction of stimulated Brillouin scattering. Self-trapping of light beams and self-steeping of light pulses in nonlinear materials were two other important innovations. Some applications today of these early ideas are outlined.

JLA Vol:21 Iss:4 (Femtosecond laser micromachining and application of hot embossing molds for microfluid device fabrication)

Authors:
Hae Woon Choi
Seon Bong
Department of Mechanical and Automotive Engineering, Keimyung University, Daegu, Republic of Korea 704–701

Dave F. Farson
Laboratory for Multiscale Processing and Characterization, The Ohio State University, 1248 Arthur E Adams Dr, Columbus, Ohio 43221

Chunmeng Lu
L. James Lee
Department of Chemical and Biomolecular Engineering, The Ohio State University, 140 W 19th Ave, Columbus, Ohio 43210

Femtosecond laser micromachining was used to create microfluid channel patterns on AISI 304L stainless steel to fabricate hot embossing mold patterns. To characterize the machining process,...

JLA Vol:21 Iss:4 (From CO₂ lasers to quantum cascade lasers—A saga of high power infrared lasers)

Authors:
C. Kumar N. Patel
Department of Physics & Astronomy, University of California, Los Angeles, California 90095 and Pranalytica, Inc., 1101 Colorado Avenue, Santa Monica, California 90401

The era of high continuous laser power in the infrared region of the spectrum started with the first demonstration of laser action on the vibrational-rotational transitions of molecules and the invention of the carbon dioxide laser [C. K. N. Patel, “Interpretation of CO2 Optical Maser Experiments,” Phys. Rev. Lett. 12, 588–590 (1964)] in 1964. The progress in the high power molecular lasers was swift and led to an explosion of scientific and practical applications i...

JLA Vol:21 Iss:4 (Historical comments on the pumping of masers and lasers)

Authors:
N. Bloembergen
Optical Sciences Center, University of Arizona, Tucson, Arizona 85721

JLA Vol:21 Iss:4 (How the laser started)

Authors:
Charles Townes
Department of Physics, University of California, Berkeley, California 94720

JLA Vol:21 Iss:4 (Improvement in wear characteristics of the AISI M2 by laser cladding and melting)

Authors:
Wayan Darmawan
Department of Forest Products, Faculty of Forestry, Bogor Agricultural University, Kampus IPB Darmaga, Bogor 16680, Indonesia

Jean Quesada
Fre´de´rique Rossi
Re´my Marchal
LABOMAP-ENSAM, rue Porte de Paris, 71250 Cluny, France

Fre´de´rique Machi
IREPA LASER, Poˆle API, 67400 Illkirch, France

Hiroshi Usuki
Department of Natural Resources, Faculty of Science and Engineering, Shimane University, Matsue 690-8504, Japan

The interest of high speed steel (HSS) for wood cutting tools remains very important because of their good tool edge accura...

JLA Vol:21 Iss:4 (Numerical model of a laser-sustained argon plasma)

Authors:
R. Akarapu
A. R. Nassar
Department of Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania 16802-6812

S. M. Copley
Applied Research Laboratory and Department of Mechanical and Nuclear Engineering, Penn State University, University Park, Pennsylvania 16802-6812

J. A. Todd
Department of Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania 16802-6812

A steady state axi-symmetric model was developed to predict the size, shape and temperature of a laser-sustained plasma in flowing argon. The power of the carbon dioxide (CO₂) laser and the free s...