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Laser Processing and Chemistry
01 Jan 1996-
TL;DR: In this paper, the authors provide an overview and fundamentals of Lasers in Medicine, Biotechnology and Arts: Lasers In Medicine and Biotechnology, Restoration and Conservation of Artworks.
Abstract: Part I Overview and Fundamentals: Introduction.- Thermal, Photophysical, and Photochemical Processes.- Reaction Kinetics and Transport of Species.- Nucleation and Cluster Formation.- Lasers, Experimental Aspects, Spatial Confinement.- Part II Temperature Distributions and Surface Melting: General Solutions of the Heat Equations.- Semi-infinite Substrates.- Infinite Slabs.- Non-uniform Media.- Surface Melting.- Part III Material Removal: Vaporization, Plasma Formation.- Nanosecond-Laser Ablation.- Ultrashort-Pulse Laser Ablation.- Etching of Metals and Insulators.- Etching of Semiconductors.- Part IV Material Deposition: Laser-CVD of Microstructures.- Growth of Fibers.- Direct Writing.- Thin-Film Formation by Laser-CVD.- Adsorbed Layers, Laser-MBE.- Liquid-Phase Deposition, Electroplating.- Thin-Film Formation by Pulsed-Laser Deposition and Laser-Induced Evaporation.- Part V Material Transformations, Synthesis and Structure Formation: Material Transformations, Laser Cleaning.- Doping.- Cladding, Alloying, and Synthesis.- Oxidation, Nitridation, and Reduction.- Transformation and Functionalization of Organic Materials.- Instabilities and Structure Formation.- Part VI Diagnostic Techniques, Plasmas: Diagnostic Techniques.- Analysis of Species and Plasmas,- Part VII Lasers in Medicine, Biotechnology and Arts: Lasers in Medicine and Biotechnology.- Restoration and Conservation of Artworks.
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TL;DR: It was found that the structure and morphology also affect the energy transport among tissue constituents and therefore the ablation efficiency of biological tissues is increased.
Abstract: Author(s): Vogel, Alfred; Venugopalan, Vasan | Abstract: The mechanisms of pulsed laser ablation of biological tissues were studied. The transiently empty space created between the fiber tip and the tissue surface improved the optical transmission to the target and thus increased the ablation efficiency. It was found that the structure and morphology also affect the energy transport among tissue constituents.
1,861 citations
TL;DR: In this article, the experimental observation of keyhole-mode laser melting in a laser powder-bed fusion additive manufacturing setting for 316L stainless steel is presented, and the conditions required to transition from conduction controlled melting to keyholemode melting are identified.
981 citations
TL;DR: In this article, the authors present a survey on the recent progress in laser ablation of a solid target in a confining liquid for the synthesis of nanocrystals with focus on the mechanism of the nanocrystal growth.
898 citations
TL;DR: The observation of self-cooling of a micromirror by radiation pressure inside a high-finesse optical cavity is reported, indicating changes in intensity in a detuned cavity, provide the mechanism for entropy flow from the mirror’s oscillatory motion to the low-entropy cavity field.
Abstract: Cooling of mechanical resonators is currently a popular topic in many fields of physics including ultra-high precision measurements1, detection of gravitational waves, and the study of the transition between classical and quantum behaviour of a mechanical system. Here we report the observation of self-cooling of a micromirror by radiation pressure inside a high-finesse optical cavity. In essence, changes in intensity in a detuned cavity, as caused by the thermal vibration of the mirror, provide the mechanism for entropy flow from the mirror's oscillatory motion to the low-entropy cavity field. The crucial coupling between radiation and mechanical motion was made possible by producing free-standing micromirrors of low mass (m ≈ 400 ng), high reflectance (more than 99.6%) and high mechanical quality (Q ≈ 10,000). We observe cooling of the mechanical oscillator by a factor of more than 30; that is, from room temperature to below 10 K. In addition to purely photothermal effects we identify radiation pressure as a relevant mechanism responsible for the cooling. In contrast with earlier experiments, our technique does not need any active feedback. We expect that improvements of our method will permit cooling ratios beyond 1,000 and will thus possibly enable cooling all the way down to the quantum mechanical ground state of the micromirror.
867 citations
Cites methods from "Laser Processing and Chemistry"
...(b) The cantilever is a doubly clamped free standing Bragg mirror (520 µm long, 120 µm wide and 2.4 µm thick) that has been fabricated by using UV excimer-laser ablation in combination with a dry-etching process [ 26 ]....
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TL;DR: In the present article, attempts are made to give an overview of the basic principles behind the coating techniques as well as advantageous features such as bioactivity and biocompatibility associated with these coatings.
Abstract: With an ageing population, war, and sports related injuries there is an ever-expanding requirement for hard tissue replacement such as bone. Engineered artificial scaffold biomaterials with appropriate mechanical properties, surface chemistry and surface topography are in a great demand for enhancing cell attachment, cell growth and tissue formation at such defect sites. Most of these engineering techniques are aimed at mimicking the natural organization of the bone tissues and thereby create a conducive environment for bone regeneration. As the interaction between the cells and tissues with biomaterials at the tissue–implant interface is a surface phenomenon, surface properties play a major role in determining both the biological response to implants and the material response to the physiological condition. Hence surface engineering of biomaterials is aimed at modifying the material and biological responses through changes in surface properties while still maintaining the bulk mechanical properties of the implant. Therefore, there has been a great thrust towards development of Ca–P-based surface coatings on various metallic and nonmetallic substrates for load bearing implant applications such as hip joint prosthesis, knee joint prosthesis and dental implants. Typical coating methodologies like ion beam assisted deposition, plasma spray deposition, pulsed laser physical vapor deposition, magnetron sputtering, sol–gel derived coatings, electrodeposition, micro-arc oxidation and laser deposition are extensively studied at laboratory scale. In the present article, attempts are made to give an overview of the basic principles behind the coating techniques as well as advantageous features such as bioactivity and biocompatibility associated with these coatings. A strong emphasis will be given on laser-induced textured and bioactive coatings obtained by the author's research group [A. Kurella, N.B. Dahotre, Journal of Biomedical Applications 20 (2005) 5–50; A. Kurella, N.B. Dahotre, Acta Biomaterialia 2 (2006) 677–688; A. Kurella, N.B. Dahotre, Journal of Minerals, Metals and Materials Society (JOM) 58 (2006) 64–66; A. Kurella, N.B. Dahotre, Journal of Materials Science: Materials in Medicine 17 (2006) 565–572; P.G. Engleman, A. Kurella, A. Samant, C.A. Blue, N.B. Dahotre, Journal of Minerals, Metals and Materials Society (JOM) 57 (2005) 46–50; R. Singh, A. Kurella, N.B. Dahotre, Journal of Biomaterials Applications 21 (2006) 46–72; S.R. Paital, N.B. Dahotre, Biomedical Materials 2 (2007) 274–281; S.R. Paital, N.B. Dahotre, 2009, Acta Biomaterialia, doi:10.1016/j.actbio.2009.03.004 ; R. Singh, N.B. Dahotre, Journal of Materials Science: Materials in Medicine 18 (2007) 725–751.]. Since cells are sensitive to topographical features ranging from mesoscale to nanoscale, formation of these features by both pulsed and continuous wave Nd:YAG laser system will be highlighted. This can also be regarded as advancement towards third generation biomaterials which are bioinert, bioactive and which once implanted will stimulate cell adhesion, proliferation and growth at the interface. Further, an overview of various bio-implants and bio-devices and materials used for these kinds of devices, performance factors such as mechanical and corrosion behavior and surface science associated with these materials are also explained. As the present article is aimed at describing the multidisciplinary nature of this exciting field it also provides a common platform to understand this subject in a simple way for students, researchers, teachers and engineers in the fields ranging from medicine, dentistry, biology, materials science, biomedicine, biomechanics to physics.
597 citations