CO 2 LASER – OPTIMISATION AND APPLICATION Edited by Dan C. Dumitras CO 2 Laser – Optimisation and Application Edited by Dan C. Dumitras Published by InTech Janeza Trdine 9, 51000 Rijeka, Croatia Copyright © 2012 InTech All chapters are Open Access distributed under the Creative Commons Attribution 3.0 license, which allows users to download, copy and build upon published articles even for commercial purposes, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. After this work has been published by InTech, authors have the right to republish it, in whole or part, in any publication of which they are the author, and to make other personal use of the work. Any republication, referencing or personal use of the work must explicitly identify the original source. As for readers, this license allows users to download, copy and build upon published chapters even for commercial purposes, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. Notice Statements and opinions expressed in the chapters are these of the individual contributors and not necessarily those of the editors or publisher. No responsibility is accepted for the accuracy of information contained in the published chapters. The publisher assumes no responsibility for any damage or injury to persons or property arising out of the use of any materials, instructions, methods or ideas contained in the book. Publishing Process Manager Maja Bozicevic Technical Editor Teodora Smiljanic Cover Designer InTech Design Team First published March, 2012 Printed in Croatia A free online edition of this book is available at www.intechopen.com Additional hard copies can be obtained from orders@intechopen.com CO 2 Laser – Optimisation and Application, Edited by Dan C. Dumitras p. cm. ISBN 978-953-51-0351-6 Contents Preface IX Part 1 Basic Processes 1 Chapter 1 CO 2 Laser Photoacoustic Spectroscopy: I. Principles 3 Dan C. Dumitras, Ana Maria Bratu and Cristina Popa Chapter 2 CO 2 Laser Photoacoustic Spectroscopy: II. Instrumentation and Applications 43 Dan C. Dumitras, Ana Maria Bratu and Cristina Popa Chapter 3 CO 2 Lasing on Non-Traditional Bands 103 Vladimir Petukhov and Vadim Gorobets Part 2 New Systems 137 Chapter 4 Ultrashort Pulses 139 Mikhail N. Polyanskiy and Marcus Babzien Chapter 5 High Average Power Pulsed CO 2 Laser for Short Wavelength Light Sources 163 Akira Endo Chapter 6 Diffusion Cooled V-Fold CO 2 Laser 179 Rakesh Kumar Soni Chapter 7 Heterodyne Interferometer for Measurement of Electron Density in High-Pressure Plasmas 209 Keiichiro Urabe and Kunihide Tachibana Chapter 8 Transmission of CO 2 Laser Radiation Through Glass Hollow Core Microstructured Fibers 227 A. D. Pryamikov, A. F. Kosolapov, V. G. Plotnichenko and E. M. Dianov VI Contents Part 3 Material Processing 249 Chapter 9 Application of Laser-Burnishing Treatment for Improvement of Surface Layer Properties 251 Joanna Radziejewska Chapter 10 Covering with Carbon Black and Thermal Treatment by CO 2 Laser Surfaces of AISI 4340 Steel 275 G. Vasconcelos, D. C. Chagas and A. N. Dias Chapter 11 Welding of Thin Light Alloys Sheets by CO 2 Laser Beam: Magnesium Alloys 283 Afia Kouadri-David Chapter 12 CO2 Laser and Micro-Fluidics 307 Mohammadreza Riahi Chapter 13 Infrared Lasers in Nanoscale Science 325 Rui F. M. Lobo Part 4 Medical Applications 355 Chapter 14 Clinical Application of CO 2 Laser 357 Hyeong-Seok Oh and Jin-Sung Kim Chapter 15 CO2 Laser: Evidence Based Applications in Dentistry 379 Pinalben Viraparia, Joel M. White and Ram M. Vaderhobli Chapter 16 Non-Thermal, Non-Ablative CO 2 Laser Therapy (NACLT): A New Approach to Relieve Pain in Some Painful Oral Diseases 387 Nasrin Zand Chapter 17 Protons Acceleration by CO 2 Laser Pulses and Perspectives for Medical Applications 415 Pasquale Londrillo, Graziano Servizi, Andrea Sgattoni, Stefano Sinigardi, Marco Sumini and Giorgio Turchetti Preface The molecular carbon dioxide laser was invented in 1964 by C. K. N. Patel at Bell Labs. Immediately, it proved to be a high-power, continuous wave (CW) laser and a relatively high-efficiency gas laser (20-25% conversion of electrical energy into laser radiation), both in CW or pulsed operation. As a matter of fact, the CO 2 lasers are the highest-power CW lasers (more than 100 kW) and one of the highest-energy pulsed gas laser (100 kJ) that are currently available. It demonstrated the utility in different device concepts and found a wide range of applications, from basic sciences till material processing and medicine, because it has a well established technology, it is versatile, simple to operate and relatively cheap on investment and maintenance. The present book includes several contributions aiming a deeper understanding of the basic processes in the operation of CO 2 lasers (lasing on non-traditional bands, frequency stabilization, photoacoustic spectroscopy) and achievement of new systems (CO2 lasers generating ultrashort pulses or high average power, lasers based on diffusion cooled V-fold geometry, transmission of IR radiation through hollow core microstructured fibers). The second part of the book is dedicated to applications in material processing (heat treatment, welding, synthesis of new materials, micro fluidics) and in medicine (clinical applications, dentistry, non-ablative therapy, acceleration of protons for cancer treatment). The editor would like to thank all the chapter authors for their effort in completion of this book. Dan C. Dumitras National Institute for Laser, Plasma and Radiation Physics (INFLPR) Romania [...]... the linear laser spectroscopy methods is presented in Table 1 (Zharov & Letokhov, 1986) 8 CO2 Laser – Optimisation and Application Method Characteristics Absorption Fluorescence PA Spectral range Sensitivity (cm-1) Time resolution (s) Necessary conditions UV – far IR 10-5 – 10-9 1 - UV and visible Up to single atoms 1 – 10-12 Radiative channels of relaxation UV – far IR 10-7 – 10-10 1 – 10-3 Nonradiative... measurements A true revival of PA spectroscopy was due to Kerr and Atwood (Kerr & Atwood, 1968), who made the earliest experiments with a laser illuminated PA detector in 1968, and Kreuzer (Kreuzer, 1971), who first measured gas 4 CO2 Laser – Optimisation and Application concentrations using a PA detector and a laser in 1971 Later experiments by Kreuzer and collaborators (Kreuzer & Patel, 1971; Kreuzer et al.,... 10P(14) CO2 laser line By using an intracavity arrangement where the CO2 laser power was varied between 10 and 70 W, Groot (Groot, 2002) measured the saturation parameter of ethylene for several laser lines The relation of the effective absorption coefficient αe to the intrinsic absorption coefficient α is given by αe = α/(1 + P/Ps), where Ps (W) is the laser power saturation 26 CO2 Laser – Optimisation and. .. the Beer-Lambert law, the transmitted laser power in the absence of saturation is given by: P ( L ) = P ( 0 ) exp( α p L ) = P ( 0 ) exp ( αcL ) , (1) where P(0) and P(L) are the laser powers before and after the absorption cell, respectively; αp (cm-1) is the absorption coefficient at a given pressure of the gas at a specific laser 6 CO2 Laser – Optimisation and Application wavelength: αp = αc; α (cm-1... cylindrical coordinates (Hess, 1983): 14 CO2 Laser – Optimisation and Application f kmn = vs 2 k 2 αmn 2 + L πr 1/2 , (3) where vs is the sound velocity, L and r are the length and radius of the cylinder, the k, m, n indices (non-negative integers) refer to the values of the longitudinal, azimuthal, and radial modes, respectively, and αmn is the n-th root of the derivative... 4 free space viscous and thermal dissipation; diffusion effects; radiation effects; and relaxational damping (dissipative relaxation processes within polyatomic gases) Friction due to compressional motion and the transformation of organized energy into heat due to temperature gradients are responsible for the free space viscous and thermal losses 18 CO2 Laser – Optimisation and Application These two... time needed for laser tuning and the gas exchange within the cell Thus, a small volume PA cell and a fast tunable laser are a plus The availability of suitable laser sources plays a key role, as they control the sensitivity (laser power), selectivity (tuning range), and practicability (ease of use, size, cost, and reliability) that can be achieved with the photoacoustic technique The CO2 laser perfectly... longer (Hess, 1983) 10 CO2 Laser – Optimisation and Application 2.3 Typical laser photoacoustic setup A typical setup of a resonant LPAS, as used in the authors’ laboratory for gas studies, is shown in Fig 2 The continuous wave laser radiation is amplitude-modulated by a mechanical chopper operating at an acoustic resonance frequency of the PA cell It is then focused by a lens and directed through the... necessary selectivity for analyzing multicomponent mixtures by the use of line-tunable IR lasers, e.g., CO lasers (Sigrist et al., 1989) or CO2 lasers (Meyer & Sigrist, 1990) CO2 laser photoacoustic spectroscopy offers a sensitive technique for detection and monitoring of trace gases at low concentrations The CO2 laser is of special interest, as it ensures high output power in a wavelength region (9-11... reflections a standing wave pattern with pressure nodes will be formed Therefore, open pipes should have resonances when the pipe length is equal to an integer multiple of the half wavelength Bernegger and Sigrist (Bernegger & Sigrist, 1987) proved that the plane acoustic wave propagation can be modeled by the one-dimensional analogue of the electrical current flow 20 CO2 Laser – Optimisation and Application . CO 2 LASER – OPTIMISATION AND APPLICATION Edited by Dan C. Dumitras CO 2 Laser – Optimisation and Application Edited by Dan C. Dumitras. with a laser illuminated PA detector in 1968, and Kreuzer (Kreuzer, 1971), who first measured gas CO 2 Laser – Optimisation and Application 4 concentrations using a PA detector and a laser. Infrared Lasers in Nanoscale Science 325 Rui F. M. Lobo Part 4 Medical Applications 355 Chapter 14 Clinical Application of CO 2 Laser 357 Hyeong-Seok Oh and Jin-Sung Kim Chapter 15 CO2 Laser: