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:14 Iss:4 (High-energy femtosecond pulsed laser micromachining of thin film deposited silicon in self-focused air medium)

Authors:
Yuanyuan Dong
Pal Molian
Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011

Christian Zorman
Mehran Mehregany
Department of Electrical Engineering and Computer Science, Case Western Reserve University, Cleveland, Ohio 44106

The ultrashort pulsed laser ablation of silicon wafers deposited with 1 μm thin film of SiC was performed in air medium using a 1 mJ, 120 fs, 800 nm Ti:sapphire laser, the objective being to determine the self-focusing capability of air to produce nanostructures. The effects of pulse energy, the number of pulses, pulse repetition rate and x–y translation speed on t...

JLA Vol:18 Iss:4 (Threshold powers and delays for igniting propane and butane-air mixtures by cw laser-heated small particles)

Authors:
Thomas H. Dubaniewicz
National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory, 626 Cochrans Mill Road, Pittsburgh, Pennsylvania 15236

The National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory conducted a study of laser safety in potentially flammable environments. Researchers measured threshold igniting powers as a function of beam diameter for butane and propane-air mixtures by laser-heating targets placed on optical fiber tips using a 1064 nm laser. The minimum igniting powers for propane-air and butane-air were about 250 and 300 mW, respectively. Threshold igniting powers for propane-air were approxima...

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:9 Iss:3 (A power distribution model of industrial CO₂ lasers for system diagnosis)

Authors:
James G. Katter
Jay F. Tu
Mark Gartner

Industrial lasers are high power pieces of equipment that occasionally function under undesirable operating conditions. For example, the performance of a transverse‐flow d.c.‐excited gas laser can be adversely affected by many factors such as electrode arcing, poor lens and mirror cleanliness, focusing problems, improper gas mixture composition, poor gas quality, poor beam stability, poor beam path cleanliness, operator error, poor maintenance, poor chiller water temperature and flow rate stability, and improper laser beam ramp‐in/ramp‐out rates. Many of these factors which occur in ...

JLA Vol:4 Iss:1 (Laser Triangulation Range Sensors: A Study of Performance Limitations)

Authors:
Michael Buzinski
Alan Levine
Warren H. Stevenson
Applied Optics Laboratory, School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907

Optical triangulation is a very old method of determining absolute distance to an object. In recent years laser range sensors utilizing this principle have seen growing use, particularly in the auto industry. More accurate versions are being employed for dimensional inspection operations where the sensor is often mounted on a coordinate measuring machine. Such a system offers the potential for rapid non‐contact dimensional metrology. However, there are several factors which must be taken int...

JLA Vol:17 Iss:2 (Feedback control effects on dimensions and defects of H13 tool steel by direct metal deposition process)

Authors:
Y. Hua
J. Choi
Department of Mechanical and Aerospace Engineering and Engineering Mechanics, University of Missouri, Rolla, Missouri 65409-1060

As a promising and novel manufacturing technology, laser aided direct metal deposition (DMD) process produces near-net-shape functional metal parts directly from the computer aided design (CAD) model. In-process feedback control has been recognized as a critical element to ensure the dimensional accuracy as well as near-net-shape production. Furthermore, process parameters should be delicately controlled to produce defect-free parts with superior mechanical properties. A closed loop real-time optical height control system...

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...

JLA Vol:23 Iss:4 (Thermal diffusivity measurement of silver nanofluid by thermal lens technique)

Authors:
Reza Zamiri
Department of Physics, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia

B. Z. Azmi
Department of Physics,Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia and Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia

E. Shahriari
Kazim Naghavi
E. Saion
Zahid Rizwan
M. S. Husin
Department of Physics, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia

The thermal lens technique was utilized in silver nanofluid containing silver nanopartic...

JLA Vol:6 Iss:1 (Amending the CDRH performance standard for laser products)

Authors:
Jerome E. Dennis
Office of Compliance and Surveillance Center for Devices and Radiological Heath, US Food and Drug Administration, Silver Springs, MD, U.S.A.

The most recent amendments to the Federal performance standard for laser products became effective in 1985 and 1986. At this time, the Center for Devices and Radiological Health (CDRH) is making public its intention to amend the standard again and is inviting suggestions and comments. The amendments that are now under consideration are based upon advances in the sciences of photobiology and hazard evaluation. They are also intended to harmonize with developments in international standards for similar products, and to cla...