JLA Vol:24 Iss:4 (Morphology of nanoscale structures on fused silica surfaces from interaction with temporally tailored femtosecond pulses)

Authors:
Lars Englert
Matthias Wollenhaupt
Cristian Sarpe
Dirk Otto
Thomas Baumert
Institut fuer Physik and CINSaT, Universitaet Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel, Germany

Laser control of two basic ionization processes on fused silica, i.e., multiphoton ionization and avalanche ionization, with temporally asymmetric pulse envelopes is investigated. Control leads to different final electron densities/energies as the direct temporal intensity profile and the time inverted intensity profile address the two ionization processes in a different fashion. This results in observed different thresholds for material modification o...

JLA Vol:5 Iss:2 (Experimental Method for Determining the Coherence Length of CW Lasers Using a Michelson Interferometer)

Authors:
Sami Alaruri
Allison Gas Turbine Division, General Motors Corporation, Sensor Development Group

Theoretical analysis of the relationship between coherence length and the resonant‐longitudinal modes in an optical cavity is given. A Michelson interferometer is used to measure the coherence lengths of two CW He‐Ne laser cavities. Analysis of the experimental measurements shows good agreement with the theoretically predicted values.

JLA Vol:16 Iss:2 (Investigation of weld cracking in Nd:yttrium–aluminum–garnet keyhole spot welding of materials used in optoelectronic packaging)

Authors:
Geoff J. Shannon
Unitek Miyachi Corporation, 1820 S. Myrtle Avenue, Monrovia, California 91017

Bernard Q. Li
Honeywell VCSEL Optical Division, Minnesota

The welding of a problematic optical device weld joint between dissimilar materials is investigated in depth. The original material combination of cold rolled steel 1010 with 6 μm of gold coating and 304 L produced consistent weld cracking. The CRS1010 material was fixed, however the other component was open to material selection. The materials tested were 304 L stainless steel, kovar, invar, and Carpenter high permeability 49 alloy. The effect of these different materials, laser pulse parameters, lev...

JLA Vol:20 Iss:4 (Thermal stress analysis on laser scribing of glass)

Authors:
Koji Yamamoto
Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, Japan

Noboru Hasaka
Hideki Morita
Mitsuboshi Diamond Industrial Co., Ltd., 2-12-12 Minami-Kaneden, Suita, Osaka, Japan

Etsuji Ohmura
Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, Japan

In the laser scribing of glass a thermal stress is introduced into a glass substrate by means of a CO₂ laser irradiation. The glass substrate is then rapidly cooled down by water jet immediately after the irradiation. For the purpose of theoretical clarification of the factors ruling the scribable condit...

JLA Vol:1 Iss:4 (Laser Accidents: Are They All Reported and What Can Be Learned from Them?)

Authors:
R. James Rockwell
Rockwell Laser Industries, Cincinnati, Ohio

JLA Vol:22 Iss:4 (A fast method for morphological analysis of laser drilling holes)

Authors:
M. Schneider
L. Berthe
M. Muller
R. Fabbro
Laboratoire PIMM (CNRS) ARTS et METIERS ParisTech, 151 Boulevard de l’Hopital, 75013 Paris, France

This paper presents an original method for analyzing laser drilled holes. The so-called Direct Observation of Drilled hOle (DODO) method is introduced and its applications. The hole characterization that’s been made is compared with x-ray radiography and cross-section analysis. Direct Observation of Drilled hole provides instantaneously surface state, geometric shape, as well as recast layer structure, without additional operation. Since no mounting resin is used to embed the sample, th...

JLA Vol:7 Iss:1 (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: monochromaticity, directionality, and coherence. There is a faculty overlap between the Physics Department and the Laser Curriculum faculty at the college. The use o...

JLA Vol:9 Iss:2 (Laser cladding with a pulsed Nd:YAG laser and optical fibers)

Authors:
M. Brandt
D. A. Scott
S. B. Emms
J. M. Yellup

A new laser cladding technique for producing wear and corrosion resistant surfaces on engineering components is reported. The technique involves the combination of the pre‐placed and injected powder delivery methods for producing clad layers. The clad layers were formed with a pulsed Nd:YAG laser and optical fibers. The results using a nickel‐based alloy (Hastelloy C) indicate that uniform clad layers in excess of 1 mm in thickness can be achieved in a single pass with 240 W average power incident on the workpiece. The laser beam was delivered through a step‐index glass ...

JLA Vol:4 Iss:3 (High Tech or High Risk — The laser on your manufacturing floor)

Authors:
Tom Wiley
Lumonics Industrial Products Division

JLA Vol:17 Iss:1 (Microstructural characterization of dissimilar laser weld between austenitic and ferritic stainless steels)

Authors:
Rakesh Kaul
P. Ganesh
A. K. Nath
Industrial CO2 Laser Section, Centre for Advanced Technology, P. O. CAT, Indore 452 013, India

The present work involved microstructural characterization of thin sheet dissimilar laser welds between type 304 austenitic stainless steel and stabilized 17% Cr ferritic stainless steel and their comparison with welds produced by autogenous gas tungsten arc welding (GTAW). Low heat input of laser welding (LW) effectively reduced the size of fusion zone (FZ) and heat affected zone (HAZ). LW with focused laser beam (LB), preferentially displaced towards austenitic stainless steel (ASS), produced FZ with uniform and highly ref...