JLA Vol:23 Iss:4 (Heat affected zones and oxidation marks in fiber laser–oxygen cutting of mild steel)

Authors:
S. O. Al-Mashikhi
Salalah College of Technology, Engineering Department, Salalah, Oman and Faculty of Engineering, University of Nottingham, Nottingham, NG7 2RD, United Kingdom

J. Powell
A. Kaplan
Lulea University of Technology, Department of Applied Physics and Mechanical Engineering, SE 971 87 Lulea, Sweden

K. T. Voisey
Faculty of Engineering, University of Nottingham, Nottingham, NG7 2RD, United Kingdom

The effect of cutting speed and sheet thickness on surface oxidation and heat affected zones (HAZs) has been investigated for laser–oxygen cutting of mild steel sheet with a fiber laser. Optical and scanning ele...

JLA Vol:23 Iss:4 (Direct manufacturing of net-shape functional components/test-pieces for aerospace, automotive, and other applications)

Authors:
Lijue Xue
Yangsheng Li
Shaodong Wang

Laser consolidation (LC) is a novel computer-aided manufacturing process being developed by the Industrial Materials Institute of National Research Council of Canada (NRC-IMI). This rapid manufacturing process produces net-shape functional metallic parts layer-by-layer directly from a computer-aided design (CAD) model by using a laser beam to melt the injected powder and resolidifying it on the substrate or previous layer. As an alternative to the conventional machining process, this novel manufacturing process builds net-shape functional parts or features on an existing part by adding instead of removing materia...

JLA Vol:23 Iss:4 (Influence of the beam profile formulation when modeling fiber-guided laser welding)

Authors:
Alexander F. H. Kaplan
Department of Engineering Sciences and Mathematics, Luleå University of Technology,SE-971 87 Luleå, Sweden

During deep penetration laser welding, the focused laser beam determines the vapor capillary, called keyhole, and in turn the whole process physics. Beside spot diameter and Rayleigh length, the beam profile is another important but hardly explored part of the focused laser beam. The focusing of fiber-guided Yb:fiber, Nd:YAG or diode laser beams creates the complex situation that the beam has a top-hat profile in the focal plane but toward the far field transforms to a Gaussian beam. Such power density distribution was measured for a fo...

JLA Vol:23 Iss:4 (Investigation of the effect of irradiance and pulse duration in industrial percussion laser-drilling of Waspaloy)

Authors:
Robin Bright
Harris L. Marcus
Institute of Materials Science and the Department of Chemical, Materials, and Biomolecular Engineering, University of Connecticut, Storrs, Connecticut 06269-3136

As the use of pulsed lasers in the manufacture of cooling holes in high-temperature gas-turbine engine components continues to increase, understanding the material behavior during laser-material interaction and the subsequent effects on hole quality becomes critical. In this study, atomic emission spectroscopy is used to monitor the optical characteristics of ejected material during percussion laser-drilling of Waspaloy over irradiance and pulse duration values in the ranges...

JLA Vol:23 Iss:4 (Evaluation of the bone repair in defects grafted with hydroxyapatite and collagen membrane combined with laser therapy in rats)

Authors:
Marcelo Rodrigues da Cunha
Luanda de Abreu Figueira
Joa˜o Paulo Mardegan Issa
Ricardo Alexandre Junqueira Calzzani
Daniele Cristina do Prado Ribeiro
Amilton Iatecola
Mariane Silva Pettian
Array

Bone regeneration is the result of cellular events such as osteogenesis and neovascularization. However, implantation of autogenous grafts may be necessary in cases of bone mass loss due to high impact trauma. The disadvantages of the latter approach include morbidity of the donor area. Biomaterials represent an alternative for bone restoration. The most widely used compounds are collagen or hydroxyapat...

JLA Vol:24 Iss:1 (Fabrication of microtransmittance grating using laser induced backside dry etching)

Authors:
He Chao
Liu Furong
Zhou Weiping
Chen Jimin
Institute of Laser Engineering, Beijing University of Technology, Chaoyang District, Beijing 100124, China

Laser induced backside dry etching (LIBDE) is a novel technique, which applied in the micromachining and nanomachining of transparent dielectric materials used for optical elements by direct laser irradiation with the assistance of solid mediums as an absorbed layer. On the basis of exploring two different solid mediums, i.e. Al₂O₃ powder and alumina ceramic wafer as absorbers, LIBDE with 1064 nm central wavelength pulsed ytterbium doped fiber laser as the irradiation ...

JLA Vol:24 Iss:1 (Laser texturization to improve absorption and weld penetration of aluminum alloys)

Authors:
J. M. Sa´nchez-Amaya
Titania, Ensayos y Proyectos Industriales S.L. Parque Tecnolo´gico TecnoBahi´a Edif. RETSE Nave 4. Ctra. Sanlu´car Km 7. 11510, El Puerto de Santa Mari´a, Ca´diz., Spain

Z. Boukha
L. Gonza´lez-Rovira
LABCYP. Departamento de C. Materiales e Ing. Metalu´rgica y Qui´mica Inorga´nica. CASEM. Avda. Repu´blica Saharaui s/n, Puerto Real, 11510. Universidad de Ca´diz., Spain

J. Navas
J. Marti´n-Calleja
Departamento de Qui´mica Fi´sica. Facultad de Ciencias. Universidad de Ca´diz. Avda. Repu´blica Saharaui s/n, P...

JLA Vol:24 Iss:1 (Surgical treatment of squamous cell carcinoma of tongue with carbon dioxide laser radiation (CO₂))

Authors:
Walter Niccoli-Filho
Lu´cio Murilo-Santos
Aline R. C. Morosolli
Gerusa de Oliveira Moura Cardoso
Joa˜o Vitor dos Santos Canellas
Array

In this clinical study, we proposed to observe the efficacy of the treatment of squamous cell carcinoma of the tongue (SCCT) by carbon dioxide (CO₂) laser surgery. Twelve patients with SCCT were treated with excisional surgery using the CO₂ laser with a spot size of 0.8 mm, 10 W, power density of 2.5 W/cm² in continuous mode, and under constant vacuum removal of the plume. The post surgical clinical evaluations were done every day until the sutures...

JLA Vol:24 Iss:1 (Silicon(IV) phthalocyanine-loaded-nanoparticles for application in photodynamic process)

Authors:
Andreza Ribeiro Simioni
Fernando L. Primo
Antonio Claudio Tedesco
Array

The aim of this study was to evaluate the potential application of biodegradable nanoparticles containing a photosensitizer in photodynamic therapy. The poly (D,L lactic-co-glycolic acid) nanoparticles were studied by steady-state techniques, time-resolved fluorescence, and laser flash photolysis. The external morphology of the nanoparticles was established by scanning electron microscopy, and the biological activity was evaluated by in vitro cell culture by 3-(4,5 dimethyl-thiazol-2,5 biphenyl) tetrazolium bromide assay. The particles were spherical in shape exhibiting ...

JLA Vol:24 Iss:1 (Hazard class downscaling of a class 4 retina safe laser)

Authors:
Jed A. Simmons
Alan B. Marchant
Energy Dynamics Laboratory, North Logan, Utah 84341

A class 4 pulsed laser can be operated in a safe regime without reducing instantaneous irradiance or pulse energy by shortening its dwell time through duty cycle reduction or scanning. A conservative relationship for hazard distance as a function of scan rate is derived for the case of a scanning, retina safe laser.